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@inproceedings{faucris.119875624,
abstract = {We develop an analytical theory of adhesive interaction of viscoelastic spheres in quasistatic approximation. Deformations and deformation rates are assumed to be small, which allows for the application of the Hertz contact theory, modified to account for viscoelastic forces. The adhesion interactions are described by the Johnson, Kendall, and Roberts theory. Using the quasistatic approximation we derive the total force between the bodies which is not sufficiently described by the superposition of elastic, viscous and adhesive contributions, but instead an additional cross-term appears, which depends on the elastic, viscous and adhesive parameters of the material. Using the derived theory we estimate the contribution of adhesive forces to the normal coefficient of restitution and derive a criterion for the validity of the viscoelastic collision model. © 2005 Taylor & Francis Group.},
author = {Brilliantov, Nikolai V. and Pöschel, Thorsten},
booktitle = {5th International Conference on the Micromechanics of Granular Media: Powders and Grains 2005},
faupublication = {no},
isbn = {9780415383479},
pages = {505-508},
title = {{Adhesive} interactions of viscoelastic spheres},
url = {https://www.scopus.com/inward/record.url?partnerID=HzOxMe3b&scp=84857585813&origin=inward},
venue = {Stuttgart},
volume = {1},
year = {2005}
}
@article{faucris.122020404,
abstract = {We study the relation of permeability and morphology for porous structures composed of randomly placed overlapping circular or elliptical grains, so-called Boolean models. Microfluidic experiments and lattice Boltzmann simulations allowus to evaluate a power-lawrelation between theEuler characteristic of the conducting phase and its permeability. Moreover, this relation is so far only directly applicable to structures composed of overlapping grains where the grain density is known a priori. We develop a generalization to arbitrary structures modeled by Boolean models and characterized by Minkowski functionals. This generalization works well for the permeability of the void phase in systems with overlapping grains, but systematic deviations are found if the grain phase is transporting the fluid. In the latter case our analysis reveals a significant dependence on the spatial discretization of the porous structure, in particular the occurrence of single isolated pixels. To link the results to percolation theory we performed Monte Carlo simulations of the Euler characteristic of the open cluster, which reveals different regimes of applicability for our permeability-morphology relations close to and far away from the percolation threshold.},
author = {Scholz, Christian and Klatt, Michael and Mecke, Klaus and Wirner, Frank and Hirneise, Daniel and Schröder-Turk, Gerd and Bechinger, Clemens},
doi = {10.1103/PhysRevE.92.043023},
faupublication = {yes},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Direct} relations between morphology and transport in {Boolean} models},
volume = {92},
year = {2015}
}
@article{faucris.117458924,
abstract = {We study experimentally the dissipation of energy in a rotating cylinder which is partially filled by granular material. We consider the range of angular velocity corresponding to continous and stationary flow of the granulate. In this regime, the stationary state depends on the angular velocity and on the filling mass. For a wide interval of filling levels we find a universal behavior of the driving torque required to sustain the stationary state as a function of the angular velocity. The result may be of relevance to industrial applications, e.g. to understand the power consumption of ball mills or rotary kilns and also for damping applications where mechanical energy has to be dissipated in a controlled wa},
author = {Sack, Achim and Pöschel, Thorsten},
doi = {10.1038/srep26833},
faupublication = {yes},
journal = {Scientific Reports},
peerreviewed = {Yes},
title = {{Dissipation} of {Energy} by {Dry} {Granular} {Matter} in a {Rotating} {Cylinder}},
volume = {6},
year = {2016}
}
@article{faucris.116714224,
abstract = {The temporal evolution of a water-sand interface driven by gravity is experimentally investigated. By means of a Fourier analysis of the evolving interface the growth rates are determined for the different modes appearing in the developing front. To model the observed behavior we apply the idea of the Rayleigh-Taylor instability for two stratified fluids. Carrying out a linear stability analysis we calculate the growth rates from the corresponding dispersion relations for finite and infinite cell sizes. Based on the theoretical results the viscosity of the suspension is estimated to be approximately 100 times higher than that of pure water, in agreement with other experimental findings.},
author = {Schröter, Matthias and Lange, Adrian and Scherer, Michael A. and Engel, Andreas and Rehberg, Ingo},
faupublication = {no},
journal = {European Physical Journal B},
pages = {475-484},
peerreviewed = {Yes},
title = {{Fingering} instability in a water-sand mixture},
volume = {4},
year = {1998}
}
@article{faucris.109843844,
author = {Meerson, Baruch and Pöschel, Thorsten and Sasorov, Pavel V. and Schwager, Thomas},
doi = {10.1103/PhysRevE.69.059905},
faupublication = {no},
journal = {Physical Review E},
pages = {059905-1},
peerreviewed = {Yes},
title = {{Erratum}: {Giant} fluctuations at a granular phase separation threshold ({Physical} {Review} {E} (2004) 69 (021302))},
url = {http://journals.aps.org/pre/abstract/10.1103/PhysRevE.69.059905},
volume = {69},
year = {2004}
}
@misc{faucris.111217964,
author = {Michelsen, Britt},
faupublication = {yes},
peerreviewed = {automatic},
title = {{Validation} of {Dune} {Simulations} using {OpenFOAM}},
year = {2012}
}
@article{faucris.213262130,
abstract = {DNA-programmable assembly has been used to deliberately synthesize hundreds of different colloidal crystals spanning dozens of symmetries, but the complexity of the achieved structures has so far been limited to small unit cells. We assembled DNA-modified triangular bipyramids (~250-nanometer long edge, 177-nanometer short edge) into clathrate architectures. Electron microscopy images revealed that at least three different structures form as large single-domain architectures or as multidomain materials. Ordered assemblies, isostructural to clathrates, were identified with the help of molecular simulations and geometric analysis. These structures are the most sophisticated architectures made via programmable assembly, and their formation can be understood based on the shape of the nanoparticle building blocks and mode of DNA functionalization.},
author = {Lin, Haixin and Lee, Sangmin and Sun, Lin and Spellings, Matthew and Engel, Michael and Glotzer, Sharon C. and Mirkin, Chad A.},
doi = {10.1126/science.aal3919},
faupublication = {yes},
journal = {Science},
note = {EAM Import::2019-03-13},
pages = {931-935},
peerreviewed = {Yes},
title = {{Clathrate} colloidal crystals},
volume = {355},
year = {2017}
}
@article{faucris.122565784,
abstract = {Disks interacting via particular potentials self-organize into triangles that stabilize mosaics with 10-, 12-, 18- and 24-fold symmetry, as revealed by computer simulations. Discoveries of further novel quasicrystals may now be within reach.},
author = {Engel, Michael and Glotzer, Sharon C.},
faupublication = {no},
journal = {Nature Physics},
pages = {185-186},
peerreviewed = {Yes},
title = {{News} & {Views}: {A} trinagular affair},
volume = {10},
year = {2014}
}
@article{faucris.109817224,
abstract = {We report the experimental discovery of a remarkable organization of the set of self-generated periodic oscillations in the parameter space of a nonlinear electronic circuit. When control parameters are suitably tuned, the wave pattern complexity of the periodic oscillations is found to increase orderly without bound. Such complex patterns emerge forming self-similar discontinuous phases that combine in an artful way to produce large discontinuous spirals of stability. This unanticipated discrete accumulation of stability phases was detected experimentally and numerically in a Duffing-like proxy specially designed to bypass noisy spectra conspicuously present in driven oscillators. Discontinuous spirals organize the dynamics over extended parameter intervals around a focal point. They are useful to optimize locking into desired oscillatory modes and to control complex systems. The organization of oscillations into discontinuous spirals is expected to be generic for a class of nonlinear oscillators.},
author = {Sack, Achim and Freire, J. G. and Lindberg, Erik and Pöschel, Thorsten and Gallas, Jason},
doi = {10.1038/srep03350},
faupublication = {yes},
journal = {Scientific Reports},
peerreviewed = {Yes},
title = {{Discontinuous} spirals of stable periodic oscillations},
volume = {3},
year = {2013}
}
@article{faucris.209668980,
abstract = {Clusters in systems as diverse as metal atoms, virus proteins, noble
gases, and nucleons have properties that depend sensitively on the
number of constituent particles. Certain numbers are termed ‘magic’
because they grant the system with closed shells and exceptional
stability. To this point, magic number clusters have been exclusively
found with attractive interactions as present between atoms. Here we
show that magic number clusters exist in a confined soft matter system
with negligible interactions. Colloidal particles in an emulsion droplet
spontaneously organize into a series of clusters with precisely defined
shell structures. Crucially, free energy calculations demonstrate that
colloidal clusters with magic numbers possess higher thermodynamic
stability than those off magic numbers. A complex kinetic pathway is
responsible for the efficiency of this system in finding its minimum
free energy configuration. Targeting similar magic number states is a
strategy towards unique configurations in finite self-organizing systems
across the scale},
author = {Wang, Junwei and Mbah Chrameh, Fru and Przybilla, Thomas and Apeleo Zubiri, Benjamin and Spiecker, Erdmann and Engel, Michael and Vogel, Nicolas},
doi = {10.1038/s41467-018-07600-4},
faupublication = {yes},
journal = {Nature Communications},
peerreviewed = {Yes},
title = {{Magic} number colloidal clusters as minimum free energy structures},
volume = {9},
year = {2018}
}
@article{faucris.107702584,
abstract = {When a narrow tube inserted into a static container filled with particles is subjected to vertical vibration, the particles rise in the tube, much resembling the ascending motion of a liquid column in a capillary tube. To gain insights on the particle dynamics dictating this phenomenon – which we term **granular capillarity** – we numerically investigate the system using the Discrete Element Method (DEM). We reproduce the dynamical process of the granular capillarity and analyze the vertical motion of the individual particles in the tube, as well as the average vertical velocities of the particles. Our simulations show that the height of the granular column fluctuates in a periodic or period-doubling manner as the tube vibrates, until a steady-state (capillary) height is reached. Moreover, our results for the average vertical velocity of the particles in the tube at different radial positions suggest that granular convection is one major factor underlying the particle-based dynamics that lead to the granular capillarity phenomenon.},
author = {Fan, Fengxian and Liu, Ju and Ribeiro Parteli, Eric Josef and Pöschel, Thorsten},
doi = {10.1051/epjconf/201714016008},
faupublication = {yes},
journal = {EPJ Web of Conferences},
peerreviewed = {unknown},
title = {{Vertical} motion of particles in vibration-induced granular capillarity},
volume = {140},
year = {2017}
}
@article{faucris.116195904,
abstract = {Optically transparent immersion liquids with refractive index (𝑛∼1.77) to match the sapphire-based aplanatic numerical aperture increasing lens (aNAIL) are necessary for achieving deep 3D imaging with high spatial resolution. We report that antimony tribromide (SbBr3) salt dissolved in liquid diiodomethane (CH2I2) provides a new high refractive index immersion liquid for optics applications. The refractive index is tunable from 𝑛=1.74 (pure) to 𝑛=1.873 (saturated), by adjusting either salt concentration or temperature; this allows it to match (or even exceed) the refractive index of sapphire. Importantly, the solution gives excellent light transmittance in the ultraviolet to near-infrared range, an improvement over commercially available immersion liquids. This refractive-index-matched immersion liquid formulation has enabled us to develop a sapphire-based aNAIL objective that has both high numerical aperture (NA=1.17) and long working distance (WD=12 mm). This opens up new possibilities for deep 3D imaging with high spatial resolution.},
author = {Laskar, Junaid M. and Kumar, P. Shravan and Herminghaus, Stephan and Daniels, Karen E. and Schröter, Matthias},
doi = {10.1364/AO.55.003165},
faupublication = {yes},
journal = {Applied Optics},
peerreviewed = {Yes},
title = {{High} refractive index immersion liquid for superresolution {3D} imaging using sapphire-based aplanatic numerical aperture increasing lens optics},
volume = {Vol.55},
year = {2016}
}
@article{faucris.110035904,
abstract = {The kinetic energy distribution function satisfying the Boltzmann equation is studied analytically and numerically for a system of inelastic hard spheres in the case of binary collisions. Analytically, this function is shown to have a similarity form in the simple cases of uniform or steady-state flows. This determines the region of validity of hydrodynamic description. The latter is used to construct the phase diagram of granular systems and discriminate between clustering instability and inelastic collapse. The molecular dynamics results support analytical results, but also exhibit a novel fluctuational breakdown of mean-field descriptions.},
author = {Pöschel, Thorsten and Esipov, Sergei E.},
doi = {10.1007/BF02183630},
faupublication = {no},
journal = {Journal of Statistical Physics},
keywords = {Boltzmann equation; Granular hydrodynamics; Granular temperature},
pages = {1385-1395},
peerreviewed = {Yes},
title = {{The} granular phase diagram},
volume = {86},
year = {1997}
}
@article{faucris.119476324,
abstract = {
We show that the orientation and morphology of bedforms occurring on top of Pluto’s smooth ice coats are consistent with an aeolian origin under conditions of unidirectional flow. From scaling relations for dune size as a function of attributes of atmosphere and sediments, we find that the average diameter of the granular particles constituting such bedforms — assuming an aeolian origin — lies within the range 600 *μ*m< d < 750 *μ*m. Our findings show that, owing to the effect of hysteresis in the minimal threshold wind velocity for saltation, dune migration on Pluto can occur under wind speeds that are common to Earth and Mars.

},
author = {Ribeiro Parteli, Eric Josef and Pöschel, Thorsten},
doi = {10.1051/epjconf/201714014010},
faupublication = {yes},
journal = {EPJ Web of Conferences},
peerreviewed = {unknown},
title = {{Barchan} dunes on {Pluto}?},
volume = {140},
year = {2017}
}
@article{faucris.109896644,
abstract = {We present a simple model for the friction of two solid bodies moving against each other. In a self-consistent way we can obtain the dependence of the macroscopic friction force as a function of the driving velocity, the normal force and the ruggedness of the surfaces in contact. Our results are discussed in the context of friction laws used in earthquake models. © 1993.},
author = {Pöschel, Thorsten and Herrmann, Hans J.},
doi = {10.1016/0378-4371(93)90233-T},
faupublication = {no},
journal = {Physica A-Statistical Mechanics and Its Applications},
pages = {441-448},
peerreviewed = {Yes},
title = {{A} simple geometrical model for solid friction},
volume = {198},
year = {1993}
}
@article{faucris.114379804,
abstract = {We report a detailed investigation of the stability of a CO 2 laser with feedback as described by a six-dimensional rate-equations model which provides satisfactory agreement between numerical and experimental results. We focus on experimentally accessible parameters, like bias voltage, feedback gain, and the bandwidth of the feedback loop. The impact of decay rates and parameters controlling cavity losses are also investigated as well as control planes which imply changes of the laser physical medium. For several parameter combinations, we report stability diagrams detailing how laser spiking and bursting is organized over extended intervals. Laser pulsations are shown to emerge organized in several hitherto unseen regular and irregular phases and to exhibit a much richer and complex range of behaviors than described thus far. A significant observation is that qualitatively similar organization of laser spiking and bursting can be obtained by tuning rather distinct control parameters, suggesting the existence of unexpected symmetries in the laser control space.},
author = {Gallas, Jason A. and Gallas, Jason and Freire, J. G. and Meucci, Riccardo and Areccchi, Fortunato},
doi = {10.1063/1.4916923},
faupublication = {yes},
journal = {Chaos},
pages = {097607},
peerreviewed = {Yes},
title = {{Self}-organization of pulsing and bursting in a {CO2} laser with opto-electronic feedback},
volume = {25},
year = {2015}
}
@article{faucris.110054824,
abstract = {Numerical simulations of a dissipative hard sphere gas reveal a dependence of the cooling rate on correlation of the particle velocities due to inelastic collisions. We propose a coefficient which characterizes the velocity correlations in the two-particle velocity distribution function and express the temperature decay rate in terms of this coefficient. The analytical results are compared with numerics.},
author = {Pöschel, Thorsten and Brilliantov, Nikolai and Schwager, Thomas},
doi = {10.1142/S012918310200411X},
faupublication = {no},
journal = {International Journal of Modern Physics C},
keywords = {Dissipative gases; Granular gases; Kinetic gas theory; Many-particle systems; Velocity correlations},
pages = {1263-1272},
peerreviewed = {Yes},
title = {{Violation} of molecular chaos in dissipative gases},
volume = {13},
year = {2002}
}
@article{faucris.119401524,
abstract = {
Besides its importance for science and engineering, the process of drop formation from a homogeneous jet or at a nozzle is of great aesthetic appeal. In this paper, we introduce a low-cost setup for classroom use to produce quasi-high-speed recordings with high temporal and spatial resolution of the formation of drops at a nozzle. The visualization of the process can be used for quantitative analysis of the underlying physical phenomena.

},
author = {Sack, Achim and Pöschel, Thorsten},
doi = {10.1119/1.4979657},
faupublication = {yes},
journal = {American Journal of Physics},
peerreviewed = {Yes},
title = {{Dripping} faucet in extreme spatial and temporal resolution},
volume = {85},
year = {2017}
}
@article{faucris.122902824,
abstract = {The phase separation instability that occurs in a system of nearly elastically colliding hard spheres driven by a thermal wall was investigated. It was demonstrated that if the aspect ratio of the confining box exceeded a threshold value the phase separation could be predicted by granular hydrostatics. It was found that in a wide region of aspect ratios around the threshold, the system was dominated by fluctuations. The two possible scenarios of the origin of the giant fluctuations were also discussed.},
author = {Meerson, Baruch and Pöschel, Thorsten and Sasorov, Pavel V. and Schwager, Thomas},
doi = {10.1103/PhysRevE.69.021302},
faupublication = {no},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Giant} fluctuations at a granular phase separation threshold},
volume = {69},
year = {2004}
}
@inproceedings{faucris.106255204,
abstract = {The properties of dense granular systems are analyzed from a hydrodynamical point of view, based on conservation laws for the particle number density and linear momentum. We discuss averaging problems associated with the nature of such systems and the peculiarities of the sources of noise. We perform a quantitative study by combining analytical methods and numerical results obtained by ensemble-averaging of data on creep during compaction and molecular dynamics simulations of convective flow. We show that numerical integration of the hydrodynamic equations gives the expected evolution for the time-dependent fields.},
address = {Bellingham, WA, United States},
author = {Salueña, Clara and Esipov, Sergei E. and Pöschel, Thorsten},
booktitle = {Smart Structures and Materials 1997: Passive Damping and Isolation},
doi = {10.1117/12.274205},
faupublication = {no},
isbn = {0819424587},
pages = {2-11},
publisher = {Society of Photo-Optical Instrumentation Engineers},
title = {{Hydrodynamic} fluctuations and averaging problems in dense granular flows},
venue = {San Diego, CA, USA},
volume = {3045},
year = {1997}
}
@article{faucris.109998944,
abstract = {A first-principle continuum-mechanics expression for the rolling friction coefficient is obtained for the rolling motion of a viscoelastic sphere on a hard plane. It relates the friction coefficient to the viscous and elastic constants of the sphere material. The relation obtained refers to the case when the deformation of the sphere ξ is small, the velocity of the sphere V is much less than the speed of sound in the material and when the characteristic time ξ/V is much larger than the dissipative relaxation times of the viscoelastic material. To our knowledge this is the first "first-principle" expression of the rolling friction coefficient which does not contain empirical parameters.},
author = {Brilliantov, Nikolai and Pöschel, Thorsten},
doi = {10.1209/epl/i1998-00281-7},
faupublication = {no},
journal = {EPL - Europhysics Letters},
pages = {511-516},
peerreviewed = {Yes},
title = {{Rolling} friction of a viscous sphere on a hard plane},
volume = {42},
year = {1998}
}
@article{faucris.117261584,
abstract = {Progress in nanocrystal synthesis and self-assembly enables the formation of highly ordered superlattices. Recent studies focused on spherical particles with tunable attraction and polyhedral particles with anisotropic shape, and excluded volume repulsion, but the effects of shape on particle interaction are only starting to be exploited. Here we present a joint experimental–computational multiscale investigation of a class of highly faceted planar lanthanide fluoride nanocrystals (nanoplates, nanoplatelets). The nanoplates self-assemble into long-range ordered tilings at the liquid–air interface formed by a hexane wetting layer. Using Monte Carlo simulation, we demonstrate that their assembly can be understood from maximization of packing density only in a first approximation. Explaining the full phase behaviour requires an understanding of nanoplate-edge interactions, which originate from the atomic structure, as confirmed by density functional theory calculations. Despite the apparent simplicity in particle geometry, the combination of shape-induced entropic and edge-specific energetic effects directs the formation and stabilization of unconventional long-range ordered assemblies not attainable otherwise.},
author = {Millan, Jaime A. and Murray, Christopher B. and Xing, Guozhong and Collins, Joshua E. and Kagan, Cherie R. and Engel, Michael and Chen, Jun and Qi, Liang and Li, Ju and Glotzer, Sharon C. and Li, Wenbin and Ye, Xingchen},
doi = {10.1038/nchem.1651},
faupublication = {no},
journal = {Nature Chemistry},
pages = {466-473},
peerreviewed = {Yes},
title = {{Competition} of shape and interaction patchiness for self-assembling nanoplates},
volume = {5},
year = {2013}
}
@article{faucris.106881324,
abstract = {The properties of systems composed of atoms interacting though discrete potentials are dictated by a series of events which occur between pairs of atoms. There are only four basic event types for pairwise discrete potentials and the square-well/shoulder systems studied here exhibit them all. Closed analytical expressions are derived for the on-event kinetic energy distribution functions for an atom, which are distinct from the Maxwell-Boltzmann distribution function. Exact expressions are derived that directly relate the pressure and temperature of equilibrium discrete potential systems to the rates of each type of event. The pressure can be determined from knowledge of only the rate of core and bounce events. The temperature is given by the ratio of the number of bounce events to the number of disassociation/association events. All these expressions are validated with event-driven molecular dynamics simulations and agree with the data within the statistical precision of the simulations. © 2010 American Institute of Physics.},
author = {Bannerman, Marcus and Lue, Leo},
doi = {10.1063/1.3486567},
faupublication = {yes},
journal = {Journal of Chemical Physics},
peerreviewed = {Yes},
title = {{Exact} on-event expressions for discrete potential systems},
volume = {133},
year = {2010}
}
@book{faucris.122056484,
abstract = {The CO laser is a complex dynamical system that has been investigated extensively both experimentally and through numerical simulations. As a result, a number of models exist for this laser, famed for providing satisfactory agreement between numerical and experimental observations. But the laser involves a large number of freely tunable control parameters whose impact on its performance and stability is not known in detail. The spontaneous emergence and organization of laser stability phases are also poorly understood. Here, we review recent progress in the classification of laser spiking, periodic or nonperiodic self-pulsations, predicted for CO lasers with modulated parameters and with feedback, instantaneous or delayed. The unfolding of spiking is classified with the help of numerically obtained high-resolution stability charts for experimentally accessible control parameters. Such stability charts display novel regular and irregular features, suggesting that the laser control parameter planes harbor remarkable symmetries not yet accounted for theoretically but which are experimentally within reach. High-resolution stability charts put stringent tests on the reliability and accuracy of current models in forecasting laser dynamics.},
author = {Gallas, Jason},
doi = {10.1016/bs.aamop.2016.01.001},
faupublication = {yes},
keywords = {CO2 laser stability; Laser spiking organization; Laser stability charts},
peerreviewed = {unknown},
publisher = {Academic Press Inc.},
series = {Advances in Atomic, Molecular, and Optical Physics},
title = {{Spiking} {Systematics} in {Some} {CO2} {Laser} {Models}},
volume = {65},
year = {2016}
}
@article{faucris.218995799,
abstract = {Gas bubbles immersed in a liquid and flowing through a large pressure gradient undergo volumetric deformation in addition to possible deviatoric deformation. While the high density liquid phase can be assumed to be an incompressible fluid, the gas phase needs to be modeled as a compressible fluid for such bubble flow problems. The Rayleigh-Plesset (RP) equation describes such a bubble undergoing volumetric deformation due to changes in pressure in the ambient incompressible fluid in the presence of capillary force at its boundary, assuming axisymmetric dynamics. We propose a compressible-incompressible coupling of Smoothed Particle Hydrodynamics (SPH) and validate this coupling against the RP model in two dimensions. This study complements the SPH simulations of a different class of compressible-incompressible systems where an outer compressible phase affects the dynamics of an inner incompressible phase. For different density ratios, a sinusoidal pressure variation is applied to the ambient incompressible liquid and the response of the bubble in terms of volumetric deformation is observed and compared with the solutions of the axisymmetric RP equation. (C) 2018 Elsevier Ltd. All rights reserved.},
author = {Nair, Prapanch and Tomar, Gaurav},
doi = {10.1016/j.compfluid.2018.11.015},
faupublication = {yes},
journal = {Computers & Fluids},
month = {Jan},
note = {CRIS-Team WoS Importer:2019-05-28},
pages = {301-308},
peerreviewed = {Yes},
title = {{Simulations} of gas-liquid compressible-incompressible systems using {SPH}},
volume = {179},
year = {2019}
}
@incollection{faucris.218986563,
abstract = {The pioneers of the theory of classical kinetic equations are Rudolf Clausius (1822–1888), James Clerk Maxwell (1831–1879) and Ludwig Boltzmann (1844–1906). Their theories are based on the classical dynamics of particles in the phase space according to Liouville and on detailled studies of the classical mechanics of collisions between neutral molecules.},
author = {Ebeling, Werner and Pöschel, Thorsten},
booktitle = {Lectures on Quantum Statistics},
doi = {10.1007/978-3-030-05734-3_8},
faupublication = {yes},
isbn = {978-3-030-05734-3},
note = {CRIS-Team Scopus Importer:2019-05-28},
pages = {233-266},
peerreviewed = {unknown},
publisher = {Springer Verlag},
series = {Lecture Notes in Physics},
title = {{Non}-equilibrium: {Kinetic} equations},
volume = {953},
year = {2019}
}
@article{faucris.117267964,
abstract = {All hard, convex shapes are conjectured by Ulam to pack more densely than spheres(1), which have a maximum packing fraction of phi = pi/root 18 approximate to 0.7405. Simple lattice packings of many shapes easily surpass this packing fraction(2,3). For regular tetrahedra, this conjecture was shown to be true only very recently; an ordered arrangement was obtained via geometric construction with phi = 0.7786 (ref. 4), which was subsequently compressed numerically to phi = 0.7820 (ref. 5), while compressing with different initial conditions led to phi = 0.8230 ( ref. 6). Here we show that tetrahedra pack even more densely, and in a completely unexpected way. Following a conceptually different approach, using thermodynamic computer simulations that allow the system to evolve naturally towards high-density states, we observe that a fluid of hard tetrahedra undergoes a first-order phase transition to a dodecagonal quasicrystal(7-10), which can be compressed to a packing fraction of phi = 0.8324. By compressing a crystalline approximant of the quasicrystal, the highest packing fraction we obtain is phi = 0.8503. If quasicrystal formation is suppressed, the system remains disordered, jams and compresses to phi = 0.7858. Jamming and crystallization are both preceded by an entropy-driven transition from a simple fluid of independent tetrahedra to a complex fluid characterized by tetrahedra arranged in densely packed local motifs of pentagonal dipyramids that form a percolating network at the transition. The quasicrystal that we report represents the first example of a quasicrystal formed from hard or non-spherical particles. Our results demonstrate that particle shape and entropy can produce highly complex, ordered structures.},
author = {Engel, Michael and Haji-Akbari, Amir and Keys, Aaron S. and Zheng, Xiaoyu and Petschek, Rolfe G. and Palffy-Muhoray, Peter and Glotzer, Sharon C.},
doi = {10.1038/nature08641},
faupublication = {no},
journal = {Nature},
pages = {773-U91},
peerreviewed = {Yes},
title = {{Disordered}, quasicrystalline and crystalline phases of densely packed tetrahedra},
volume = {462},
year = {2009}
}
@article{faucris.107702144,
abstract = {When a thin tube is dipped into water, the water will ascend to a certain height, against the action of gravity. While this effect, termed capillarity, is well known, recent experiments have shown that agitated granular matter reveals a similar behavior. Namely, when a vertical tube is inserted into a container filled with granular material and is then set into vertical vibration, the particles rise up along the tube. In the present Letter, we investigate the effect of granular capillarity by means of numerical simulations and show that the effect is caused by convection of the granular material in the container. Moreover, we identify two regimes of behavior for the capillary height H_{c}∞ depending on the tube-to-particle-diameter ratio, D/d. For large D/d, a scaling of H_{c}∞ with the inverse of the tube diameter, which is reminiscent of liquids, is observed. However, when D/d decreases down to values smaller than a few particle sizes, a uniquely granular behavior is observed where H_{c}∞ increases linearly with the tube diameter.},
author = {Fan, Fengxian and Ribeiro Parteli, Eric Josef and Pöschel, Thorsten},
doi = {10.1103/PhysRevLett.118.218001},
faupublication = {yes},
journal = {Physical Review Letters},
peerreviewed = {unknown},
title = {{Origin} of {Granular} {Capillarity} {Revealed} by {Particle}-{Based} {Simulations}},
volume = {118},
year = {2017}
}
@article{faucris.119284264,
abstract = {Chaos and regularity are routinely discriminated by using Lyapunov exponents distilled from the norm of orthogonalized Lyapunov vectors, propagated during the temporal evolution of the dynamics. Such exponents are mean-field-like averages that, for each degree of freedom, squeeze the whole temporal evolution complexity into just a single number. However, Lyapunov vectors also contain a step-by-step record of what exactly happens with the angles between stable and unstable manifolds during the whole evolution, a big-data information permanently erased by repeated orthogonalizations. Here, we study changes of angles between invariant subspaces as observed during temporal evolution of Hénon (tm) s system. Such angles are calculated numerically and analytically and used to characterize self-similarity of a chaotic attractor. In addition, we show how standard tools of dynamical systems may be angle-enhanced by dressing them with informations not difficult to extract. Such angle-enhanced tools reveal unexpected and practical facts that are described in detail. For instance, we present a video showing an angle-enhanced bifurcation diagram that exposes from several perspectives the complex geometrical features underlying the attractors. We believe such findings to be generic for extended classes of systems.},
author = {Gallas, Jason and Beims, Marcus W.},
doi = {10.1038/srep18859},
faupublication = {yes},
journal = {Scientific Reports},
peerreviewed = {Yes},
title = {{Manifold} angles, the concept of self-similarity, and angle-enhanced bifurcation diagrams},
volume = {6},
year = {2016}
}
@article{faucris.111557204,
abstract = {We study actively rotating granular particles manufactured by rapid prototyping. Such particles, as introduced in Ref. [1], convert vibrational motion into rotational motion via tilted elastic legs in a circular arrangement at the bottom of the particle. We extend the original design of the particles to make them suitable for mass-fabrication via rapid prototyping. The rotational velocity is measured in dependence of the driving frequency and amplitude. We find two different regimes of motion. For small amplitudes the particle performs a slow and stable rotation, while above a certain threshold the particle starts to perform a precission and consequently rotates significantly faster.},
author = {Scholz, Christian and Pöschel, Thorsten},
faupublication = {yes},
journal = {Revista Cubana de Fisica },
pages = {37-38},
peerreviewed = {unknown},
title = {{Actively} rotating granular particles manufactured by rapid prototyping},
url = {http://www.mss.cbi.fau.de/content/uploads/granular_particles_revcubfis_2016.pdf},
volume = {33},
year = {2016}
}
@article{faucris.122771704,
abstract = {We propose a model for collisions between particles of a granular material and calculate the restitution coefficients for the normal and tangential motion as functions of the impact velocity from considerations of dissipative viscoelastic collisions. Existing models of impact with dissipation as well as the classical Hertz impact theory are included in the present model as special cases. We find that the type of collision (smooth, reflecting or sticky) is determined by the impact velocity and by the surface properties of the colliding grains. We observe a rather nontrivial dependence of the tangential restitution coefficient on the impact velocity.},
author = {Brilliantov, Nikolai and Spahn, Frank and Hertzsch, Jan-Martin and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.53.5382},
faupublication = {no},
journal = {Physical Review E},
pages = {5382-5392},
peerreviewed = {Yes},
title = {{Model} for collisions in granular gases},
volume = {53},
year = {1996}
}
@article{faucris.117271264,
abstract = {It has recently been shown that identical, isotropic particles can form complex crystals and quasicrystals. In order to understand the relation between the particle interaction and the structure, which it stabilizes, the phase behavior of a class of two-scale potentials is studied. In two dimensions, the phase diagram features many phases previously observed in experiment and simulation. The three-dimensional system includes the sigma phase with 30 particles per unit cell, not grown in simulations before, and an amorphous state, which we found impossible to crystallize in molecular dynamics. We suggest that the appearance of structural complexity in monodisperse systems is related to competing nearest neighbor distances and discuss implications of our result for the self-assembly of macromolecules.},
author = {Engel, Michael and Trebin, Hans-Rainer},
doi = {10.1524/zkri.2008.1040},
faupublication = {no},
journal = {Zeitschrift für Kristallographie},
keywords = {Crystal growth;Molecular Dynamics Simulations;Quasicrystals;Macromolecules;Glasses},
month = {Jan},
pages = {721-725},
peerreviewed = {Yes},
title = {{Structural} complexity in monodisperse systems of isotropic particles},
volume = {223},
year = {2008}
}
@article{faucris.223993539,
abstract = {Complex crystallization pathways are common in protein crystallization, tetrahedrally coordinated systems, and biomineralization, where single or multiple precursors temporarily appear before the formation of the crystal. The emergence of precursors is often explained by a unique property of the system, such as short-range attraction, directional bonding, or ion association. But, structural characteristics of the prenucleation phases found in multistep crystallization remain unclear, and models are needed for testing and expanding the understanding of fluid-to-solid ordering pathways. Here, we report 3 instances of 2-step crystallization of hard-particle fluids. Crystallization in these systems proceeds via a high-density precursor fluid phase with prenucleation motifs in the form of clusters, fibers and layers, and networks, respectively. The density and diffusivity change across the fluid–fluid phase transition increases with motif dimension. We observe crystal nucleation to be catalyzed by the interface between the 2 fluid phases. The crystals that form are complex, including, notably, a crystal with 432 particles in the cubic unit cell. Our results establish the existence of complex crystallization pathways in entropic systems and reveal prenucleation motifs of various dimensions.},
author = {Lee, Sangmin and Teich, Erin G. and Engel, Michael and Glotzer, Sharon C.},
doi = {10.1073/pnas.1905929116},
faupublication = {yes},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
keywords = {2-step crystallization; Colloidal crystallization; Entropic crystallization; Fluid–fluid phase transition; Liquid–liquid phase transition},
note = {CRIS-Team Scopus Importer:2019-08-06},
pages = {14843-14851},
peerreviewed = {Yes},
title = {{Entropic} colloidal crystallization pathways via fluid–fluid transitions and multidimensional prenucleation motifs},
volume = {116},
year = {2019}
}
@article{faucris.116719504,
abstract = {A granular mixture of particles of two sizes that is shaken vertically will in most cases segregate. If the larger particles accumulate at the top of the sample, this is called the Brazil-nut effect (BNE); if they accumulate at the bottom, it is called the reverse Brazil-nut effect (RBNE). While this process is of great industrial importance in the handling of bulk solids, it is not well understood. In recent years ten different mechanisms have been suggested to explain when each type of segregation is observed. However, the dependence of the mechanisms on driving conditions and material parameters and hence their relative importance is largely unknown. In this paper we present experiments and simulations where both types of particles are made from the same material and shaken under low air pressure, which reduces the number of mechanisms to be considered to seven. We observe both BNE and RBNE by varying systematically the driving frequency and amplitude, diameter ratio, ratio of total volume of small to large particles, and overall sample volume. All our results can be explained by a combination of three mechanisms: a geometrical mechanism called void filling, transport of particles in sidewall-driven convection rolls, and thermal diffusion, a mechanism predicted by kinetic theory. (c) 2006 American Institute of Physics.},
author = {Schröter, Matthias and Swinney, Harry L. and Ulrich, Stephan and Kreft, Jennifer and Swift, Jack B.},
doi = {10.1103/PhysRevE.74.011307},
faupublication = {no},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Mechanisms} in the size segregation of a binary granular mixture},
volume = {74},
year = {2006}
}
@article{faucris.119753304,
abstract = {The structural evolution of a nanopowder by repeated dispersion and settling can lead to characteristic fractal substructures. This is shown by numerical simulations of a two-dimensional model agglomerate of adhesive rigid particles. The agglomerate is cut into fragments of a characteristic size , which then are settling under gravity. Repeating this procedure converges to a loosely packed structure, the properties of which are investigated: (a)The final packing density is independent of the initialization, (b) the short-range correlation function is independent of the fragment size, (c) the structure is fractal up to the fragmentation scale with a fractal dimension close to 1.7, and (d) the relaxation time increases linearly with. © 2008 The American Physical Society.},
author = {Schwager, Thomas and Wolf, Dietrich E. and Pöschel, Thorsten},
doi = {10.1103/PhysRevLett.100.218002},
faupublication = {no},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Fractal} substructure of a nanopowder},
volume = {100},
year = {2008}
}
@article{faucris.107138064,
abstract = {Ratchets are simple mechanical devices which combine spatial asymmetry and nonequilibrium to produce counterintuitive transport of particles. The operation and properties of *linear* ratchets have already been extensively explored. However, very little is known about *circular granular* ratchets, startling devices able to convert vertical vibrations into rotations of the device. Here, we report results of systematic numerical investigations of the operational characteristics of circular granular ratchets. Several distinct behaviors are identified and explained in terms of the inner flow fields of the ratchet. All dynamical regimes found are robust and should not be difficult to observe in laboratory experiments.},
author = {Müller, Patric and Gallas, Jason and Pöschel, Thorsten},
doi = {10.1038/s41598-017-12588-w},
faupublication = {yes},
journal = {Scientific Reports},
peerreviewed = {Yes},
title = {{Dynamical} regimes and stability of circular granular ratchets},
volume = {7},
year = {2017}
}
@article{faucris.109917764,
abstract = {In horizontally shaken granular material different types of pattern formation have been reported. We want to deal with the convection instability which has been observed in experiments and which recently has been investigated numerically. Using two dimensional molecular dynamics we show that the convection pattern depends crucially on the inelastic properties of the material. The concept of restitution coefficient provides arguments for the change of the behaviour with varying inelasticity.},
author = {Salueña, Clara and Pöschel, Thorsten},
doi = {10.1007/s101890050006},
faupublication = {no},
journal = {European Physical Journal E},
pages = {55-59},
peerreviewed = {Yes},
title = {{Convection} in horizontally shaken granular material},
volume = {1},
year = {2000}
}
@article{faucris.122887864,
abstract = {A two-dimensional cellular automaton is introduced to model the flow and jamming of vehicular traffic in cities. Each site of the automaton represents a crossing where a finite number of cars can wait approaching the crossing from each of the four directions. The flow of cars obeys realistic traffic rules. We investigate the dependence of the average velocity of cars on the global traffic density. At a critical threshold for the density the average velocity reduces drastically caused by jamming. For the low-density regime we provide analytical results which agree with the numerical results. © 1995.},
author = {Freund, Jan A. and Pöschel, Thorsten},
doi = {10.1016/0378-4371(95)00170-C},
faupublication = {no},
journal = {Physica A-Statistical Mechanics and Its Applications},
pages = {95-113},
peerreviewed = {Yes},
title = {{A} statistical approach to vehicular traffic},
volume = {219},
year = {1995}
}
@article{faucris.110027984,
abstract = {The Superimposé webserver performs structural similarity searches with a preference towards 3D structure-based methods. Similarities can be detected between small molecules (e.g. drugs), parts of large structures (e.g. binding sites of proteins) and entire proteins. For this purpose, a number of algorithms were implemented and various databases are provided. Superimposé assists the user regarding the selection of a suitable combination of algorithm and database. After the computation on our server infrastructure, a visual assessment of the results is provided. The structure-based in silico screening for similar drug-like compounds enables the detection of scaffold-hoppers with putatively similar effects. The possibility to find similar binding sites can be of special interest in the functional analysis of proteins. The search for structurally similar proteins allows the detection of similar folds with different backbone topology. The Superimposé server is available at: http://bioinformatics.charite.de/superimpose.},
author = {Bauer, Raphael A. and Bourne, Philip E. and Formella, Arno and Frömmel, Cornelius and Gille, Christoph and Goede, Andrean and Guerler, Aysam and Hoppe, Andreas and Knapp, Ernst-Walter and Pöschel, Thorsten and Wittig, Burghardt and Ziegler, Valentin and Preissner, Robert},
doi = {10.1093/nar/gkn285},
faupublication = {no},
journal = {Nucleic acids research},
peerreviewed = {Yes},
title = {{Superimpose}: a {3D} structural superposition server.},
volume = {36},
year = {2008}
}
@article{faucris.215447040,
abstract = {An impressive ping-pong ball cannon can be made by placing a bottle of liquid nitrogen at the bottom of a container and quickly covering it with, say, 1500 ping-pong balls. The liquid turns rapidly into a gas whose mounting pressure explodes the bottle, sending a swarm of balls upward out of the container. Surprisingly, the container also moves upward. This is a counterintuitive effect because the balance of forces, that is, Newton's third law does not seem to allow the container to move upwards. We explain the effect as a consequence of granular jamming in combination with Coulomb's friction law. (C) 2019 American Association of Physics Teachers.},
author = {Pöschel, Thorsten and Nasato, Daniel S. and Parteli, Eric J. R. and Gallas, Jason and Müller, Patric},
doi = {10.1119/1.5088805},
faupublication = {yes},
journal = {American Journal of Physics},
note = {CRIS-Team WoS Importer:2019-04-04},
pages = {255-263},
peerreviewed = {Yes},
title = {{Ping}-pong ball cannon: {Why} do barrel and balls fly in the same direction?},
volume = {87},
year = {2019}
}
@article{faucris.109959124,
abstract = {A gas of particles which collide inelastically if their impact velocity exceeds a certain value is investigated. In difference to common granular gases, cluster formation occurs only as a transient phenomenon. We calculate the decay of temperature due to inelastic collisions. In spite of the drastically reduced dissipation at low temperature the temperature surprisingly converges to zero. © 2003 Published by Elsevier Science B.V.},
author = {Pöschel, Thorsten and Brilliantov, Nikolai and Schwager, Thomas},
doi = {10.1016/S0378-4371(03)00206-1},
faupublication = {no},
journal = {Physica A-Statistical Mechanics and Its Applications},
keywords = {Cluster formation; Granular gas; Molecular dynamics; Velocity dependent coefficient of restitution},
pages = {274-283},
peerreviewed = {Yes},
title = {{Long}-time behavior of granular gases with impact-velocity dependent coefficient of restitution},
url = {http://www.sciencedirect.com/science/article/pii/S0378437103002061},
volume = {325},
year = {2003}
}
@inproceedings{faucris.117367624,
author = {Engel, Michael},
booktitle = {DPG Frühjahrstagung},
date = {2013-03-11/2013-03-15},
faupublication = {no},
peerreviewed = {unknown},
title = {{Self}-assembly and packing of polyhedra into complex crystal structures},
venue = {Regensburg},
year = {2013}
}
@article{faucris.110308924,
abstract = {We investigate jammed granular matter in a slowly rotating drum partially filled with granular material and find a state of polydirectional stability. In this state, the material responds elastically to small stresses in a wide angular interval while it responds by plastic deformation when subjected to small stresses outside this interval of directions. We describe the evolution of the granulate by means of a rate equation and find quantitative agreement with the experiment. The state of polydirectional stability complements the fragile state, where the material responds elastically to small applied stresses only in a certain direction but even very small stresses in any other direction would lead to plastic deformations. Similar to fragile matter, polydirectionally stable matter is created in a dynamic process by self-organization. © 2013 American Physical Society.},
author = {Zimber, Fabian and Kollmer, Jonathan and Pöschel, Thorsten},
doi = {10.1103/PhysRevLett.111.168003},
faupublication = {yes},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Polydirectional} stability of granular matter},
volume = {111},
year = {2013}
}
@article{faucris.109620544,
abstract = {Mechanisms that stabilize quasicrystals are much discussed but not finally resolved. We confirm the random tiling hypothesis and its predictions in a fully atomistic decagonal quasicrystal model by calculating the free energy and the phason elastic constants over a wide range of temperatures. The Frenkel-Ladd method is applied for the phonon part, and an approach of uncorrelated phason flips is applied for the configurational part. When lowering the temperature, a phase transition to an approximant occurs. Close to the transition temperature, one of the phason elastic constants becomes soft. © 2012 American Physical Society.},
author = {Engel, Michael and Kiselev, Alexander and Trebin, Hans-Rainer},
doi = {10.1103/PhysRevLett.109.225502},
faupublication = {no},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Confirmation} of the {Random} {Tiling} {Hypothesis} for a {Decagonal} {Quasicrystal}},
volume = {109},
year = {2012}
}
@article{faucris.110053724,
abstract = {The onset of surface fluidization of granular material in a vertically vibrated container, z = A cos (ωt), is studied experimentally. Recently, for a column of spheres it has been theoretically found (see T. Pöschel, T. Schwager, C. Salueña, Phys. Rev. E 62, 1361 (2000)) that the particles lose contact if a certain condition for the acceleration amplitude z̈ ≡ Aω/g = f(ω) holds. This result is in disagreement with other findings where the criterion z̈ = z̈ = const was found to be the criterion of fluidization. We show that for a column of spheres a critical acceleration is not a proper criterion for fluidization and compare the results with theory.},
author = {Renard, S. and Schwager, Thomas and Pöschel, Thorsten and Salueña, Clara},
doi = {10.1007/s101890170133},
faupublication = {no},
journal = {European Physical Journal E},
pages = {233-239},
peerreviewed = {Yes},
title = {{Vertically} shaken column of spheres. {Onset} of fluidization},
volume = {4},
year = {2001}
}
@article{faucris.109888944,
abstract = {We discuss a new optimization strategy, which considerably improves the effectivity of evolutionary algorithms applied to a certain class of optimization problems. The basic principle is to solve first a simpler related problem, which is constructed by introducing additional degrees of freedom to the landscape. Starting from the solution in this simplified landscape we remove stepwise the added degrees of freedom. Our optimization strategy is demonstrated for a sample problem.},
author = {Buchholtz, Volkhard and Pöschel, Thorsten},
doi = {10.1142/S0218127497000546},
faupublication = {no},
journal = {International Journal of Bifurcation and Chaos},
pages = {751-757},
peerreviewed = {Yes},
title = {{Adaptive} evolutionary optimization of team work},
volume = {7},
year = {1997}
}
@article{faucris.114764804,
abstract = {An algorithm for the exact calculation of the overlap volume of a sphere and a tetrahedron, wedge, or hexahedron is described. The method can be used to determine the exact local solid fractions for a system of spherical, non-overlapping particles contained in a complex mesh, a question of significant relevance for the numerical solution of many fluid-solid interaction problems. While challenging due to the limited machine precision, a numerically robust version of the calculation maintaining high computational efficiency is devised. The method is evaluated with respect to the numerical precision and computational cost. It is shown that the exact calculation is only limited by the machine precision and can be applied to a wide range of size ratios, contrary to previously published methods. Eliminating this constraint enables the usage of meshes with higher resolution near the system boundaries for coupled CFD-DEM simulations. The numerical robustness is further illustrated by applying the method to highly deformed mesh elements. The full source code of the reference implementation is made available under an open-source license.},
author = {Strobl, Severin and Formella, Arno and Pöschel, Thorsten},
doi = {10.1016/j.jcp.2016.02.003},
faupublication = {yes},
journal = {Journal of Computational Physics},
keywords = {Local solid fraction; Numerical robustness; Overlap volume; Sphere-mesh overlap},
pages = {158-172},
peerreviewed = {Yes},
title = {{Exact} calculation of the overlap volume of spheres and mesh elements},
volume = {311},
year = {2016}
}
@article{faucris.213287957,
abstract = {We argue that the alignment of Lyapunov vectors provides a quantitative criterion to predict catastrophes, i.e. the imminence of large-amplitude events in chaotic time-series of observables generated by sets of ordinary differential equations. Explicit predictions are reported for a Rössler oscillator and for a semiconductor laser with optoelectronic feedback.},
author = {Beims, Marcus W. and Gallas, Jason},
doi = {10.1038/srep37102},
faupublication = {yes},
journal = {Scientific Reports},
note = {EAM Import::2019-03-13},
peerreviewed = {Yes},
title = {{Alignment} of {Lyapunov} {Vectors}: {A} {Quantitative} {Criterion} to {Predict} {Catastrophes}?},
volume = {6},
year = {2016}
}
@article{faucris.119735484,
abstract = {We simulate the dynamical behavior of M elevators serving N floors of a building in which a Poisson distribution of persons call elevators. Our simulation reproduces the jamming effect typically seen in large buildings when a large number of persons decide to leave the building simultaneously. The collective behavior of the elevators involves characteristics similar to those observed in systems of coupled oscillators. In addition, there is an apparently rule-free critical population density above which elevators start to arrive synchronously at the ground floor. © 1994 The American Physical Society.},
author = {Pöschel, Thorsten and Gallas, Jason A.},
doi = {10.1103/PhysRevE.50.2654},
faupublication = {no},
journal = {Physical Review E},
pages = {2654-2659},
peerreviewed = {Yes},
title = {{Synchronization} effects in the dynamical behavior of elevators},
volume = {50},
year = {1994}
}
@article{faucris.109923924,
abstract = {The transmission of kinetic energy through chains of inelastically colliding spheres is investigated for the case of constant coefficient of restitution ε=const and impact-velocity-dependent coefficient ε(υ) for viscoelastic particles. We derive a theory for the optimal distribution of particle masses which maximize the energy transfer along the chain and check it numerically. We found that for ε=const, the mass distribution is a monotonous function which does not depend on the value of ε. In contrast, for ε(υ) the mass distribution reveals a pronounced maximum, depending on the particle properties and on the chain length. The system investigated demonstrates that even for small and simple systems, the velocity dependence of the coefficient of restitution may lead to new effects with respect to the same systems under the simplifying approximation ε=const. ©2001 The American Physical Society.},
author = {Pöschel, Thorsten and Brilliantov, Nikolai},
doi = {10.1103/PhysRevE.63.021505},
faupublication = {no},
journal = {Physical Review E},
pages = {1-9},
peerreviewed = {Yes},
title = {{Extremal} collision sequences of particles on a line: {Optimal} transmission of kinetic energy},
volume = {63},
year = {2001}
}
@article{faucris.122106204,
abstract = {The dynamics of sheared inelastic-hard-sphere systems is studied using nonequilibrium molecular-dynamics simulations and direct simulation Monte Carlo. In the molecular-dynamics simulations Lees-Edwards boundary conditions are used to impose the shear. The dimensions of the simulation box are chosen to ensure that the systems are homogeneous and that the shear is applied uniformly. Various system properties are monitored, including the one-particle velocity distribution, granular temperature, stress tensor, collision rates, and time between collisions. The one-particle velocity distribution is found to agree reasonably well with an anisotropic Gaussian distribution, with only a slight overpopulation of the high-velocity tails. The velocity distribution is strongly anisotropic, especially at lower densities and lower values of the coefficient of restitution, with the largest variance in the direction of shear. The density dependence of the compressibility factor of the sheared inelastic-hard-sphere system is quite similar to that of elastic-hard-sphere fluids. As the systems become more inelastic, the glancing collisions begin to dominate over more direct, head-on collisions. Examination of the distribution of the times between collisions indicates that the collisions experienced by the particles are strongly correlated in the highly inelastic systems. A comparison of the simulation data is made with direct Monte Carlo simulation of the Enskog equation. Results of the kinetic model of Montanero [J. Fluid Mech. 389, 391 (1999)] based on the Enskog equation are also included. In general, good agreement is found for high-density, weakly inelastic systems. © 2009 The American Physical Society.},
author = {Bannerman, Marcus and Green, Thomas E. and Lue, Leo and Grassia, Paul},
doi = {10.1103/PhysRevE.79.041308},
faupublication = {yes},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Collision} statistics in sheared inelastic hard spheres},
volume = {79},
year = {2009}
}
@article{faucris.109937344,
abstract = {The goal of this study is to demonstrate numerically that certain hydrodynamic systems, derived from inelastic kinetic theory, give fairly good descriptions of rapid granular flows even if they are way beyond their supposed validity limits. A numerical hydrodynamic solver is presented for a vibrated granular bed in two dimensions. It is based on a highly accurate shock capturing state-of-the-art numerical scheme applied to a compressible Navier - Stokes system for granular flow. The hydrodynamic simulation of granular flows is challenging, particularly in systems where dilute and dense regions occur at the same time and interact with each other. As a benchmark experiment, we investigate the formation of Faraday waves in a two-dimensional thin layer exposed to vertical vibration in the presence of gravity. The results of the hydrodynamic simulations are compared with those of event-driven molecular dynamics and the overall quantitative agreement is good at the level of the formation and structure of periodic patterns. The accurate numerical scheme for the hydrodynamic description improves the reproduction of the primary onset of patterns compared to previous literature. To our knowledge, these are the first hydrodynamic results for Faraday waves in two-dimensional granular beds that accurately predict the wavelengths of the two-dimensional standing waves as a function of the perturbation's amplitude. Movies are available with the online version of the paper. © 2008 Cambridge University Press.},
author = {Carrillo, José A. and Pöschel, Thorsten and Salueña, Clara},
doi = {10.1017/S0022112007009792},
faupublication = {no},
journal = {Journal of Fluid Mechanics},
pages = {119-144},
peerreviewed = {Yes},
title = {{Granular} hydrodynamics and pattern formation in vertically oscillated granular disk layers},
volume = {597},
year = {2008}
}
@article{faucris.213104015,
abstract = {Hard polyhedra are a natural extension of the hard sphere model for simple fluids, but there is no general scheme for predicting the effect of shape on thermodynamic properties, even in moderate-density fluids. Only the second virial coefficient is known analytically for general convex shapes, so higher-order equations of state have been elusive. Here we investigate high-precision state functions in the fluid phase of 14 representative polyhedra with different assembly behaviors. We discuss historic efforts in analytically approximating virial coefficients up to B4 and numerically evaluating them to B8. Using virial coefficients as inputs, we show the convergence properties for four equations of state for hard convex bodies. In particular, the exponential approximant of Barlow et al. (J. Chem. Phys. 2012, 137, 204102) is found to be useful up to the first ordering transition for most polyhedra. The convergence behavior we explore can guide choices in expending additional resources for improved estimates. Fluids of arbitrary hard convex bodies are too complicated to be described in a general way at high densities, so the high-precision state data we provide can serve as a reference for future work in calculating state data or as a basis for thermodynamic integration.},
author = {Irrgang, M. Eric and Engel, Michael and Schultz, Andrew J. and Kofke, David A. and Glotzer, Sharon C.},
doi = {10.1021/acs.langmuir.7b02384},
faupublication = {yes},
journal = {Langmuir},
note = {EAM Import::2019-03-12},
pages = {11788-11796},
peerreviewed = {Yes},
title = {{Virial} {Coefficients} and {Equations} of {State} for {Hard} {Polyhedron} {Fluids}},
volume = {33},
year = {2017}
}
@article{faucris.122894684,
abstract = {The coefficient of normal restitution of colliding viscoelastic spheres is computed as a function of the material properties and the impact velocity. From simple arguments it becomes clear that, in a collision of purely repulsively interacting particles, the particles lose contact slightly before the distance of the centers of the spheres reaches the sum of the radii, that is, the particles recover their shape only after they lose contact with their collision partner. This effect was neglected in earlier calculations, which leads erroneously to attractive forces and thus to an underestimation of the coefficient of restitution. As a result we find a different dependence of the coefficient of restitution on the impact rate. © 2008 The American Physical Society.},
author = {Schwager, Thomas and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.78.051304},
faupublication = {no},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Coefficient} of restitution for viscoelastic spheres: {The} effect of delayed recovery},
volume = {78},
year = {2008}
}
@article{faucris.122166484,
abstract = {We find that a column of glass beads exhibits a well-defined transition between two phases that differ in their resistance to shear. Pulses of fluidization are used to prepare static sedimented states with well-defined particle volume fractions phi in the range 0.57-0.63. The resistance to shear is determined by slowly inserting a rod into the column of beads. Force measurements and bed height measurements both indicate that the transition occurs at phi = 0.60 for a range of speeds of the rod. Copyright (C) EPLA, 2007.},
author = {Schröter, Matthias and Radin, Charles and Swinney, Harry L. and Nägle, Sibylle},
doi = {10.1209/0295-5075/78/44004},
faupublication = {no},
journal = {EPL - Europhysics Letters},
month = {Jan},
peerreviewed = {Yes},
title = {{Phase} transition in a static granular system},
volume = {78},
year = {2007}
}
@article{faucris.113989744,
abstract = {The development of reliable strategies to optimize part production in additive manufacturing technologies hinges, to a large extent, on the quantitative understanding of the mechanical behavior of the powder particles during the application process. Since it is difficult to acquire this understanding based on experiments alone, a particle-based numerical tool for the simulation of powder application is required. In the present work, we develop such a numerical tool and apply it to investigate the characteristics of the powder layer deposited onto the part using a roller as the coating system. In our simulations, the complex geometric shapes of the powder particles are taken explicitly into account. Our results show that increasing the coating speed leads to an increase in the surface roughness of the powder bed, which is known to affect part quality. We also find that, surprisingly, powders with broader size distributions may lead to larger values of surface roughness as the smallest particles are most prone to form large agglomerates thus increasing the packing's porosity. Moreover, we find that the load on the part may vary over an order of magnitude during the coating process owing to the strong inhomogeneity of inter-particle forces in the granular packing. Our numerical tool can be used to assist - and partially replace - experimental investigations of the flowability and packing behavior of different powder systems as a function of material and process parameters.},
author = {Ribeiro Parteli, Eric Josef and Pöschel, Thorsten},
doi = {10.1016/j.powtec.2015.10.035},
faupublication = {yes},
journal = {Powder Technology},
keywords = {Additive manufacturing; Discrete element method; Numerical simulation},
pages = {96-102},
peerreviewed = {Yes},
title = {{Particle}-based simulation of powder application in additive manufacturing},
volume = {288},
year = {2016}
}
@article{faucris.122956724,
abstract = {The collision of frictional granular particles may be described by an interaction force whose normal component is that of viscoelastic spheres while the tangential part is described by the model by Cundall and Strack (G´ eotechnique 29, 47 (1979)) being the most popular tangential collision model in Molecular Dynamics simulations. Albeit being a rather complicatedmodel, governed by 5 phenomenological parameters and 2 independent initial conditions, we find that it is described by 3 independent parameters only. Surprisingly, in a wide range of parameters the corresponding coefficient of tangential restitution, εt, is well described by the simple Coulomb law with a cut-off at εt = 0. A more complex behavior of the coefficient of restitution as a function on the normal and tangential components of the impact velocity, gn and gt, including negative values of εt, is found only for very small ratio gt/gn. For the analysis presented here we neglect dissipation of the interaction in normal direction.},
author = {Schwager, Thomas and Becker, Volker and Pöschel, Thorsten},
doi = {10.1140/epje/i2007-10356-3},
faupublication = {yes},
journal = {European Physical Journal E},
pages = {107--114},
peerreviewed = {Yes},
title = {{Coefficient} of tangential restitution for viscoelastic spheres},
volume = {27},
year = {2008}
}
@article{faucris.109981564,
abstract = {When granular systems are modeled by hard spheres, particle-particle collisions are considered as instantaneous events. This implies that while the velocities change according to the collision rule, the positions of the particles are the same before and after such an event. We show that depending on the material and system parameters, this assumption may fail. For the case of viscoelastic particles we present a universal condition which allows to assess whether hard-spheremodeling and, thus, event-driven Molecular Dynamics simulations are justified. © Springer-Verlag 2012.},
author = {Müller, Patric and Pöschel, Thorsten},
doi = {10.1007/s10035-012-0324-5},
faupublication = {yes},
journal = {Granular Matter},
keywords = {Coefficient of normal restitution; Event-driven molecular dynamics; Granular gases; Hard sphere model; Viscoelastic spheres},
pages = {115-120},
peerreviewed = {Yes},
title = {{Oblique} impact of frictionless spheres: {On} the limitations of hard sphere models for granular dynamics},
volume = {14},
year = {2012}
}
@article{faucris.213298491,
abstract = {Disordered dielectric materials with structural correlations show unconventional optical behavior: They can be transparent to long-wavelength radiation, while at the same time have isotropic band gaps in another frequency range. This phenomenon raises fundamental questions concerning photon transport through disordered media. While optical transparency in these materials is robust against recurrent multiple scattering, little is known about other transport regimes like diffusive multiple scattering or Anderson localization. Here, we investigate band gaps, and we report Anderson localization in 2D disordered dielectric structures using numerical simulations of the density of states and optical transport statistics. The disordered structures are designed with different levels of positional correlation encoded by the degree of stealthiness \textgreekq. To establish a unified view, we propose a correlation-frequency (\textgreekq--\textgreekn) transport phase diagram. Our results show that, depending only on \textgreekq, a dielectric material can transition from localization behavior to a band gap crossing an intermediate regime dominated by tunneling between weakly coupled states.},
author = {Froufe-Perez, Luis S. and Engel, Michael and Jose Saenz, Juan and Scheffold, Frank},
doi = {10.1073/pnas.1705130114},
faupublication = {yes},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
note = {EAM Import::2019-03-13},
pages = {9570-9574},
peerreviewed = {Yes},
title = {{Band} gap formation and {Anderson} localization in disordered photonic materials with structural correlations},
volume = {114},
year = {2017}
}
@article{faucris.116704764,
abstract = {Hard-sphere molecular dynamics (MD) simulation results, with six-figure accuracy in the thermodynamic equilibrium pressure, are reported and used to test a closed-virial equation-of-state. This latest equation, with no adjustable parameters except known virial coefficients, is comparable in accuracy both to Pad́ approximants, and to numerical parameterizations of MD data. There is no evidence of nonconvergence at stable fluid densities. The virial pressure begins to deviate significantly from the thermodynamic fluid pressure at or near the freezing density, suggesting that the passage from stable fluid to metastable fluid is associated with a higher-order phase transition; an observation consistent with some previous experimental results. Revised parameters for the crystal equation-of-state [R. J. Speedy, J. Phys.: Condens. Matter 10, 4387 (1998)] are also reported. © 2010 American Institute of Physics.},
author = {Bannerman, Marcus and Lue, Leo and Woodcock, Leslie V.},
doi = {10.1063/1.3328823},
faupublication = {no},
journal = {Journal of Chemical Physics},
peerreviewed = {Yes},
title = {{Thermodynamic} pressures for hard spheres and closed-virial equation-of-state},
volume = {132},
year = {2010}
}
@article{faucris.109996964,
abstract = {We report a striking effect observed experimentally in several granular materials when shaken horizontally: The material displays a recurrent alternation between a slow inflation phase, characterized by an increase in its volume, and a fast collapse phase, when the volume abruptly returns to its original value. The frequency of such phase alternations is totally decoupled from the frequency of the external drive. We argue that the inflation and collapse alternation arises from an interplay between the mechanical stability of the material and Reynolds dilatancy due to convective motion. © 2012 American Physical Society.},
author = {Pöschel, Thorsten and Rosenkranz, Dirk E. and Gallas, Jason},
doi = {10.1103/PhysRevE.85.031307},
faupublication = {yes},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Recurrent} inflation and collapse in horizontally shaken granular materials},
volume = {85},
year = {2012}
}
@article{faucris.119943164,
abstract = {
A flowing hourglass changes its weight in the course of time because of the accelerated motion of its center of mass. While this insight is not new, it is frequently said that the effect is tiny and hardly measurable. Here we present a simple experiment which allows to monitor the weight as a function of time revealing different stages, in quantitative agreement with theory.

},
author = {Sack, Achim and Pöschel, Thorsten},
doi = {10.1119/1.4973527},
faupublication = {yes},
journal = {American Journal of Physics},
month = {Jan},
peerreviewed = {Yes},
title = {{Weight} of an {Hourglass} – {Theory} and {Experiment} in {Quantitative} {Comparison}},
volume = {85},
year = {2017}
}
@article{faucris.122036024,
abstract = {Some dynamical properties for a dissipative time-dependent Lorentz gas are studied. We assume that the size of the scatterers change periodically in time. We show that for some combination of the control parameters the particles come to a complete stop between the scatterers, but for some other cases, the average velocity grows unbounded. This is the first time that the unlimited energy growth is observed in a dissipative system. Finally, we study the behavior of the average velocity as a function of the number of collisions and we show that the system is scaling invariant with scaling exponents well defined. © 2013 Elsevier B.V. All rights reserved.},
author = {Fregolente Mendes de Oliveira, Diego and Pöschel, Thorsten},
doi = {10.1016/j.physleta.2013.06.029},
faupublication = {yes},
journal = {Physics Letters A},
keywords = {Billiards; Chaos; Dissipation; Lorentz gas; Scaling},
pages = {2052-2057},
peerreviewed = {Yes},
title = {{Competition} between unlimited and limited energy growth in a two-dimensional time-dependent billiard},
volume = {377},
year = {2013}
}
@article{faucris.114385524,
abstract = {We report a numerical characterization of the stability of semiconductor lasers with delayed feedback under the simultaneous variation of the delay time \textit{τ }and the pump current P. Changes in the number of External Cavity Modes are studied as a function of the delay time while the Regular Pulse Package regime is characterized as a function of the pump current. In addition, we describe some remarkable structures observed in the \textit{τ ×P }control plane, delimiting where these and other complex regimes of laser operation exist.},
author = {Gallas, Jason A. and Junges, Leandro and Pöschel, Thorsten},
doi = {10.1140/epjd/e2013-40124-4},
faupublication = {yes},
journal = {European Physical Journal D},
pages = {149--158},
peerreviewed = {Yes},
title = {{Characterization} of the stability of semiconductor lasers with delayed feedback according to the {Lang}-{Kobayashi} model},
volume = {67},
year = {2013}
}
@article{faucris.118403604,
abstract = {The velocity distribution in a homogeneously cooling granular gas has been studied in the viscoelastic regime, when the restitution coefficient of colliding particles depends on the impact velocity. We show that for viscoelastic particles a simple scaling hypothesis is violated, i.e., that the time dependence of the velocity distribution does not scale with the mean square velocity as in the case of particles interacting via a constant restitution coefficient. The deviation from the Maxwellian distribution does not depend on time monotonically. For the case of small dissipation we detected two regimes of evolution of the velocity distribution function: Starting from the initial Maxwellian distribution, the deviation first increases with time on a collision time scale saturating at some maximal value; then it decays to zero on a much larger time scale which corresponds to the temperature relaxation. For larger values of the dissipation parameter there appears an additional intermediate relaxation regime. Analytical calculations for small dissipation agree well with the results of a numerical analysis.},
author = {Brilliantov, Nikolai and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.61.5573},
faupublication = {no},
journal = {Physical Review E},
pages = {5573-5587},
peerreviewed = {Yes},
title = {{Velocity} distribution in granular gases of viscoelastic particles},
volume = {61},
year = {2000}
}
@article{faucris.122865644,
abstract = {Advancements in the synthesis of faceted nanoparticles and colloids have spurred interest in the phase behavior of polyhedral shapes. Regular tetrahedra have attracted particular attention because they prefer local symmetries that are incompatible with periodicity. Two dense phases of regular tetrahedra have been reported recently. The densest known tetrahedron packing is achieved in a crystal of triangular bipyramids (dimers) with a packing density of 4000/4671 approximate to 85.63%. In simulation a dodecagonal quasicrystal is observed; its approximant, with periodic tiling (3.4.3(2).4), can be compressed to a packing fraction of 85.03%. Here, we show that the quasicrystal approximant is more stable than the dimer crystal for packing densities below 84% using Monte Carlo computer simulations and free energy calculations. To carry out the free energy calculations, we use a variation of the Frenkel-Ladd method for anisotropic shapes and thermodynamic integration. The enhanced stability of the approximant can be attributed to a network substructure, which maximizes the free volume (and hence the wiggle room) available to the particles and facilitates correlated motion of particles, which further contributes to entropy and leads to diffusion for packing densities below 65%. The existence of a solid-solid transition between structurally distinct phases not related by symmetry breaking - the approximant and the dimer crystal - is unusual for hard particle systems. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3651370]},
author = {Engel, Michael and Haji-Akbari, Amir and Glotzer, Sharon C.},
doi = {10.1063/1.3651370},
faupublication = {no},
journal = {Journal of Chemical Physics},
keywords = {diffusion;entropy;free energy;Monte Carlo methods;phase diagrams;quasicrystals},
peerreviewed = {Yes},
title = {{Phase} diagram of hard tetrahedra},
volume = {135},
year = {2011}
}
@incollection{faucris.218985571,
abstract = {The development of a systematic statistical theory for systems with Coulomb interactions is related to characteristic problems: 1.Debye’s screening problem, 2.Wigner’s problem of lattice formation,3.Herzfeld’s bound state problem.},
author = {Ebeling, Werner and Pöschel, Thorsten},
booktitle = {Lectures on Quantum Statistics},
doi = {10.1007/978-3-030-05734-3_6},
faupublication = {yes},
isbn = {978-3-030-05734-3},
note = {CRIS-Team Scopus Importer:2019-05-28},
pages = {171-210},
peerreviewed = {unknown},
publisher = {Springer Verlag},
series = {Lecture Notes in Physics},
title = {{Quantum} statistics of dilute plasmas},
volume = {953},
year = {2019}
}
@inproceedings{faucris.122137884,
abstract = {We investigate the collective dissipative behavior of a model granular material (steel beads) when subjected to vibration. To this end, we study the attenuation of the amplitude of an oscillating leaf spring whose free end carries a rectangular box partly filled with granulate. To eliminate the perturbing influence of gravity, the experiment was performed under conditions of microgravity during parabolic flights. Different regimes of excitation could be distinguished, namely, a gas-like state of disordered particle motion and a state where the particles slosh back and forth between the container walls in a collective way, referred to as collect-and-collide regime. For the latter regime, we provide an expression for the container size leading to maximal dissipation of energy, that also marks the transition to the gas like regime. Also for systems driven at fixed amplitude and frequency, we find both the gas regime and the collect-and-collide regime resulting in similar dissipative behavior as in the case of the attenuating vibration. © 2013 AIP Publishing LL},
author = {Kollmer, Jonathan and Sack, Achim and Heckel, Michael and Zimber, Fabian and Müller, Patric and Bannerman, Marcus and Pöschel, Thorsten},
booktitle = {7th International Conference on Micromechanics of Granular Media: Powders and Grains 2013},
doi = {10.1063/1.4812055},
faupublication = {yes},
isbn = {9780735411661},
keywords = {damping; Granular material},
pages = {811-814},
peerreviewed = {Yes},
title = {{Collective} granular dynamics in a shaken container at low gravity conditions},
venue = {Sydney, NSW},
volume = {1542},
year = {2013}
}
@article{faucris.107356744,
abstract = {We engineered an automated biomechatronics system, *MyoRobot*, for robust objective and versatile assessment of muscle or polymer materials (bio-)mechanics. It covers multiple levels of muscle biosensor assessment, e.g. membrane voltage or contractile apparatus Ca^{2+} ion responses (force resolution 1 µN, 0–10 mN for the given sensor; [Ca^{2+}] range ~ 100 nM–25 µM). It replaces previously tedious manual protocols to obtain exhaustive information on active/passive biomechanical properties across various morphological tissue levels. Deciphering mechanisms of muscle weakness requires sophisticated force protocols, dissecting contributions from altered Ca^{2+} homeostasis, electro-chemical, chemico-mechanical biosensors or visco-elastic components. From whole organ to single fibre levels, experimental demands and hardware requirements increase, limiting biomechanics research potential, as reflected by only few commercial biomechatronics systems that can address resolution, experimental versatility and mostly, automation of force recordings. Our *MyoRobot* combines optical force transducer technology with high precision 3D actuation (e.g. voice coil, 1 µm encoder resolution; stepper motors, 4 µm feed motion), and customized control software, enabling modular experimentation packages and automated data pre-analysis. In small bundles and single muscle fibres, we demonstrate automated recordings of (i) caffeine-induced-, (ii) electrical field stimulation (EFS)-induced force, (iii) pCa-force, (iv) *slack-tests* and (v) passive length-tension curves. The system easily reproduces results from manual systems (two times larger stiffness in slow over fast muscle) and provides novel insights into unloaded shortening velocities (declining with increasing slack lengths). The *MyoRobot* enables automated complex biomechanics assessment in muscle research. Applications also extend to material sciences, exemplarily shown here for spider silk and collagen biopolymer},
author = {Haug, Michael and Reischl, Barbara and Prölß, Gerhard and Pollmann, Charlotte and Buckert, Thomas and Keidel, Christian and Schürmann, Sebastian and Hock, Magdalena and Rupitsch, Stefan and Heckel, Michael and Pöschel, Thorsten and Scheibel, T and Haynl, C and Kiriaev, L and Head, Stewart I. and Friedrich, Oliver},
doi = {10.1016/j.bios.2017.12.003},
faupublication = {yes},
journal = {Biosensors and Bioelectronics},
pages = {589-599},
peerreviewed = {Yes},
title = {{The} {MyoRobot}: {A} novel automated biomechatronics system to assess voltage/{Ca2}+ biosensors and active/passive biomechanics in muscle and biomaterials},
volume = {102},
year = {2018}
}
@article{faucris.122283304,
abstract = {In particulate systems with short-range interactions, such as granular matter or simple fluids, local structure determines the macroscopic physical properties. We analyse local structure metrics derived from the Voronoi diagram of oblate ellipsoids, for various aspect ratios and global packing fractions φg. We focus on jammed static configurations of frictional ellipsoids, obtained by tomographic imaging and by discrete element method simulations. The rescaled distribution of local packing fractions φl, defined as the ratio of particle volume and its Voronoi cell volume, is found to be independent of the particle aspect ratio, and coincide with results for sphere packs. By contrast, the typical Voronoi cell shape, quantified by the Minkowski tensor anisotropy index β = β0^{2,0}, points towards a difference between random packings of spheres and those of oblate ellipsoids. While the average cell shape β of all cells with a given value of is similar in dense and loose jammed sphere packings, the structure of dense and loose ellipsoid packings differs substantially such that this does not hold true.},
author = {Schröter, Matthias and Schaller, Fabian and Kapfer, Sebastian and Hilton, James E. and Cleary, Paul W. and Mecke, Klaus and de Michele, Christiano and Schilling, Tanja and Saadatfar, Mohammad and Delaney, Gary and Schröder-Turk, Gerd},
doi = {10.1209/0295-5075/111/24002},
faupublication = {yes},
journal = {EPL},
peerreviewed = {unknown},
title = {{Non}-universal {Voronoi} cell shapes in amorphous ellipsoid packs},
volume = {111},
year = {2015}
}
@article{faucris.122088824,
abstract = {The decision whether a measured distribution complies with an equidistribution is a central element of many biostatistical methods. High throughput differential expression measurements, for instance, necessitate to judge possible over-representation of genes. The reliability of this judgement, however, is strongly affected when rarely expressed genes are pooled. We propose a method that can be applied to frequency ranked distributions and that yields a simple but efficient criterion to assess the hypothesis of equiprobable expression levels. By applying our technique to surrogate data we exemplify how the decision criterion can differentiate between a true equidistribution and a triangular distribution. The distinction succeeds even for small sample sizes where standard tests of significance (e.g. χ) fail. Our method will have a major impact on several problems of computational biology where rare events baffle a reliable assessment of frequency distributions. The program package is available upon request from the authors. © 2003 Elsevier Science Ireland Ltd. All rights reserved.},
author = {Pöschel, Thorsten and Freund, Jan A.},
doi = {10.1016/S0303-2647(03)00030-3},
faupublication = {no},
journal = {Biosystems},
keywords = {Biometrics; Finite sample statistics; Hypothesis testing; Microarray analysis},
pages = {63-72},
peerreviewed = {Yes},
title = {{How} to decide whether small samples comply with an equidistribution},
url = {http://www.sciencedirect.com/science/article/pii/S0303264703000303},
volume = {69},
year = {2003}
}
@article{faucris.222785371,
abstract = {The structure of
finite
self-assembling systems depends
sensitively on the number of constituent
building blocks. Recently, it was demonstrated that hard sphere-like colloidal particles show a
magic number effect when confined in emulsion
droplets. Geometric con-struction
rules permit a few dozen magic numbers that
correspond to a discrete series of completely
filled concentric icosahedral shells. Here, we
investigate the free energy
landscape of these colloidal clusters as a
function of the number of their constituent building blocks for system sizes up to several thousand
particles. We find that minima in the free energy landscape,
arising from the presence of filled,
concentric shells, are significantly broadened, compared to their atomic
analogues. Colloidal clusters in spherical confinement can flexibly
accommodate excess particles by
ordering icosahedrally in the cluster center while changing the structure near
the cluster surface. In between
these magic number regions, the building blocks cannot arrange into filled
shells. Instead, we observe that defects
accumulate in a single wedge and therefore only affect a few
tetrahedral grains of the cluster. We predict the existence of this wedge by simulation and confirm its presence in
experiment using electron tomography. The introduction of the wedge minimizes the free energy penalty by
confining
defects to small regions within the cluster. In addition, the remaining ordered tetrahedral grains can
relax internal strain by breaking icosahedral symmetry. Our findings demonstrate how multiple defect mechanisms
collude to form the complex free energy landscape of colloidal cluster},
author = {Wang, Junwei and Mbah Chrameh, Fru and Przybilla, Thomas and Englisch, Silvan and Spiecker, Erdmann and Engel, Michael and Vogel, Nicolas},
doi = {10.1021/acsnano.9b03039},
faupublication = {yes},
journal = {Acs Nano},
keywords = {self-assembly, hard spheres, supraparticles, emulsions, magic numbers, icosahedral symmetry, defects},
peerreviewed = {Yes},
title = {{Free} {Energy} {Landscape} of {Colloidal} {Clusters} in {Spherical} {Confinement}},
year = {2019}
}
@article{faucris.106371144,
abstract = {Chemical methods developed over the past two decades enable preparation of colloidal nanocrystals with uniform size and shape. These Brownian objects readily order into superlattices. Recently, the range of accessible inorganic cores and tunable surface chemistries dramatically increased, expanding the set of nanocrystal arrangements experimentally attainable. In this review, we discuss efforts to create next-generation materials via bottom-up organization of nanocrystals with preprogrammed functionality and self-assembly instructions. This process is often driven by both interparticle interactions and the influence of the assembly environment. The introduction provides the reader with a practical overview of nanocrystal synthesis, self-assembly, and superlattice characterization. We then summarize the theory of nanocrystal interactions and examine fundamental principles governing nanocrystal self-assembly from hard and soft particle perspectives borrowed from the comparatively established fields of micrometer colloids and block copolymer assembly. We outline the extensive catalog of superlattices prepared to date using hydrocarbon-capped nanocrystals with spherical, polyhedral, rod, plate, and branched inorganic core shapes, as well as those obtained by mixing combinations thereof. We also provide an overview of structural defects in nanocrystal superlattices. We then explore the unique possibilities offered by leveraging nontraditional surface chemistries and assembly environments to control superlattice structure and produce nonbulk assemblies. We end with a discussion of the unique optical, magnetic, electronic, and catalytic properties of ordered nanocrystal superlattices, and the coming advances required to make use of this new class of solids.},
author = {Engel, Michael and Talapin, Dmitri V. and Boles, Michael A.},
doi = {10.1021/acs.chemrev.6b00196},
faupublication = {yes},
journal = {Chemical Reviews},
pages = {11220–11289},
peerreviewed = {Yes},
title = {{Self}-{Assembly} of {Colloidal} {Nanocrystals}: {From} {Intricate} {Structures} to {Functional} {Materials}},
volume = {116},
year = {2016}
}
@article{faucris.107469824,
abstract = {This paper reports a detailed numerical study of the synchronization properties of two mutually delay-coupled semiconductor lasers in the framework of the Lang-Kobayashi model. By computing high-definition stability diagrams we predict the complex distribution of periodic and chaotic laser oscillations on the coupling versus detuning control parameter plane. Such diagrams provide details concerning the behavior of the laser intensities, quantify objectively the synchronization between their electric fields, and display in-phase and out-of-phase laser behavior. In addition, we also describe the presence of a conspicuous abrupt change in the optimal shift for the greatest value of the cross-correlation function when varying the detuning between the optical angular frequencies of the laser},
author = {Junges, Leandro and Gallas, Jason and Gavrielides, Athanasios},
doi = {10.1364/JOSAB.33.000C65},
faupublication = {yes},
journal = {Journal of the Optical Society of America B-Optical Physics},
peerreviewed = {Yes},
title = {{Synchronization} properties of two mutually delay-coupled semiconductor lasers},
year = {2016}
}
@article{faucris.123972464,
abstract = {By means of particle-based numerical simulations using the discrete element method, we address the question of how the performance of granular dampers is affected by the shape of the granular particles. In consistence with previous experiments performed with nearly spherical particles we find that independently of the particles‘ shape, the granular system is characterized by a gas-like regime for small amplitudes of the container’s oscillation and by a collect-and-collide regime for large amplitude forcing. Both regimes are separated by an optimal operation mode—the critical amplitude of the damping oscillation for which the energy dissipation is maximal—which is independent of the particle shape for given conditions of particle mass, material properties and number of particles. However, in the gas-like regime, we find that spherical particles lead to more efficient energy dissipation compared to complex shaped particles of the same mass. In this regime, a dependence on the damper’s efficiency on the particle shape is found.},
author = {Pourtavakoli, Hamzeh and Ribeiro Parteli, Eric Josef and Pöschel, Thorsten},
doi = {10.1088/1367-2630/18/7/073049},
faupublication = {yes},
journal = {New Journal of Physics},
peerreviewed = {Yes},
title = {{Effect} of particle shape on the efficiency of granular dampers},
volume = {18},
year = {2016}
}
@article{faucris.109879044,
abstract = {We consider the collision of a rough sphere with a plane by detailed analysis of the collision geometry. Using stochastic methods, the effective coefficient of restitution may be described as a fluctuating quantity whose probability density follows an asymmetric Laplace distribution. This result agrees with recent experiments by Montaine [Phys. Rev. E 84, 041306 (2011)]PLEEE81539-375510.1103/PhysRevE.84.041306. © 2014 American Physical Society.},
author = {Gunkelmann, Nina and Montaine, Marina and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.89.022205},
faupublication = {yes},
journal = {Physical Review E - Statistical, Nonlinear, and Soft Matter Physics},
peerreviewed = {Yes},
title = {{Stochastic} behavior of the coefficient of normal restitution},
volume = {89},
year = {2014}
}
@incollection{faucris.218987307,
abstract = {Planck’s theory of radiation which is the origin of quantum statistics, was semi-phenomenological based on concepts of electrodynamics, classical thermodynamics, and classical radiation theory.},
author = {Ebeling, Werner and Pöschel, Thorsten},
booktitle = {Lectures on Quantum Statistics},
doi = {10.1007/978-3-030-05734-3_3},
faupublication = {yes},
isbn = {978-3-030-05734-3},
note = {CRIS-Team Scopus Importer:2019-05-28},
pages = {55-90},
peerreviewed = {unknown},
publisher = {Springer Verlag},
series = {Lecture Notes in Physics},
title = {{Ideal} quantum gases},
volume = {953},
year = {2019}
}
@article{faucris.124183884,
abstract = {We study the diffusion of tracers (self-diffusion) in a homogeneously cooling gas of dissipative particles, using the Green-Kubo relation and the Chapman-Enskog approach. The dissipative particle collisions are described by the coefficient of restitution ε which for realistic material properties depends on the impact velocity. First, we consider self-diffusion using a constant coefficient of restitution, ε=const, as frequently used to simplify the analysis. Second, self-diffusion is studied for a simplified (stepwise) dependence of ε on the impact velocity. Finally, diffusion is considered for gases of realistic viscoelastic particles. We find that for ε=const both methods lead to the same result for the self-diffusion coefficient. For the case of impact-velocity dependent coefficients of restitution, the Green-Kubo method is, however, either restrictive or too complicated for practical application, therefore we compute the diffusion coefficient using the Chapman-Enskog method. We conclude that in application to granular gases, the Chapman-Enskog approach is preferable for deriving kinetic coefficients. © 2005 American Institute of Physics.},
author = {Brilliantov, Nikolai V. and Pöschel, Thorsten},
doi = {10.1063/1.1889266},
faupublication = {no},
journal = {Chaos},
peerreviewed = {Yes},
title = {{Self}-diffusion in granular gases: {Green}-{Kubo} versus {Chapman}-{Enskog}},
volume = {15},
year = {2005}
}
@article{faucris.119287564,
abstract = {Phase-control techniques of chaos aim to extract periodic behaviors from chaotic systems by applying weak harmonic perturbations with a suitably chosen phase. However, little is known about the best strategy for selecting adequate perturbations to reach desired states. Here we use experimental measures and numerical simulations to assess the benefits of controlling individually the three terms of a Duffing oscillator. Using a real-time analog indicator able to discriminate on-the-fly periodic behaviors from chaos, we reconstruct experimentally the phase versus perturbation strength stability areas when periodic perturbations are applied to different terms governing the oscillator. We verify the system to be more sensitive to perturbations applied to the quadratic term of the double-well Duffing oscillator and to the quartic term of the single-well Duffing oscillator.},
author = {Gallas, Jason and Meucci, Riccardo and Euzzor, Stefano and Pugliese, Eugenio and Zambrano, Samuel and Gallas, Marcia R.},
doi = {10.1103/PhysRevLett.116.044101},
faupublication = {yes},
journal = {Physical Review Letters},
month = {Jan},
peerreviewed = {Yes},
title = {{Optimal} {Phase}-{Control} {Strategy} for {Damped}-{Driven} {Duffing} {Oscillators}},
volume = {116},
year = {2016}
}
@article{faucris.212766115,
abstract = {Fluidized beds with secondary gas injection enjoy great popularity in process industry. Owing to their characteristic properties such as intense mixing of solids, excellent mass and heat transfer conditions as well as easy handling of solids, this type of apparatus is applied in various fields of process engineering nowadays. In the past decades research concerning fluidized beds with secondary gas injection has focused on understanding how solid particles and the injected gas are distributed within the apparatus. With the aid of invasive measurement techniques the region surrounding the injector nozzle was investigated with respect to the penetration depth of the gas jet above the nozzle orifice as well as the jet opening angle. A major drawback of the previously used measurement techniques consists in their invasive nature. Penetration of the injection zone by a probe can severely influence the local flow pattern and consequently has a detrimental effect on the reliability of the measured data. Therefore in the presented work for the first time the solids distribution as well as the motion of a single particle in a fluidized bed with secondary gas injection has been investigated by positron emission particle tracking (PEPT). This non-invasive technique is based on labeling one single particle, randomly selected from the bulk, radioactively, which allows for tracking its motion with high temporal and spatial resolution. The obtained data are compared with results derived from invasive measurements. Moreover PEPT-data have been used to perform investigations on the residence time behavior of particles within the jet region and the suspended phase. It could be found that the combination of invasive measurements and PEPT provide valuable information for the design and optimization of fluidized bed reactors with a well-defined injection zone.},
author = {Hensler, Timo and Tupy, Martin and Strer, Timo and Pöschel, Thorsten and Wirth, Karl-Ernst},
doi = {10.1016/j.proeng.2015.01.204},
faupublication = {yes},
journal = {Procedia Engineering},
note = {EAM Import::2019-03-08},
pages = {850-857},
peerreviewed = {unknown},
title = {{Particle} {Tracking} in {Fluidized} {Beds} with {Secondary} {Gas} {Injection}},
volume = {102},
year = {2015}
}
@inproceedings{faucris.120383164,
author = {Engel, Michael},
booktitle = {Mathematics of Distances and Applications},
date = {2012-07-02/2012-07-05},
faupublication = {no},
peerreviewed = {unknown},
title = {{Aperiodic} order in self-assembly with anisotopic particles and competing distances},
venue = {Varna},
year = {2012}
}
@article{faucris.110032604,
abstract = {The decay of temperature of a force-free granular gas in the homogeneous cooling state depends on the specific model for particle interaction. For the case of rough spheres, in recent experimental and theoretical work, the coefficient of restitution was characterized as a fluctuating quantity. We show that for such particles, the decay of temperature with time follows the law which deviates from Haff's law, T ∼ t, obtained for gases of particles interacting via a constant coefficient of restitution also from obtained for gases of viscoelastic particles. Our results are obtained from kinetic theory and are in very good agreement with Monte Carlo simulations. © IOP Publishing and Deutsche Physikalische Gesellschaft.},
author = {Gunkelmann, Nina and Serero, Dan and Pöschel, Thorsten},
doi = {10.1088/1367-2630/15/9/093030},
faupublication = {yes},
journal = {New Journal of Physics},
peerreviewed = {Yes},
title = {{Temperature} of a granular gas with regard to the stochastic nature of particle interactions},
volume = {15},
year = {2013}
}
@inproceedings{faucris.122356784,
author = {Engel, Michael},
booktitle = {EAM Symposium 2015},
date = {2015-11-23/2015-11-25},
faupublication = {no},
peerreviewed = {unknown},
title = {{Simulation} and modeling of self-assembly processes on the nanoscale and beyond},
venue = {Kloster Banz, Bad Staffelstein},
year = {2015}
}
@article{faucris.108595784,
abstract = {We report a systematic investigation of the magnetic anisotropy effects observed in the deterministic spin dynamics of a magnetic particle in the presence of a time-dependent magnetic field. The system is modeled by the Landau-Lifshitz-Gilbert equation and the magnetic field consists of two terms, a constant term and a term involving a harmonic time modulation. We consider a general quadratic anisotropic energy with three different preferential axes. The dynamical behavior of the system is represented in Lyapunov phase diagrams, and by calculating bifurcation diagrams, Poincaré sections and Fourier spectra. We find an intricate distribution of shrimp-shaped regular island embedded in wide chaotic phases. Anisotropy effects are found to play a key role in defining the symmetries of regular and chaotic stability phases.},
author = {Gallas, Jason and Perez, Laura M. and Bragard, Jean and Mancini, Hector and Cabanas, Ana M. and Suarez, Omar J. and Laroze, David},
doi = {10.3934/nhm.2015.10.209},
faupublication = {yes},
journal = {Networks and Heterogeneous Media},
pages = {209--221},
peerreviewed = {unknown},
title = {{Effect} of anisotropies on the magnetization dynamics},
volume = {10},
year = {2015}
}
@article{faucris.122017104,
abstract = {A computer aided method using symbolic computations that enables the calculation of the source terms (Boltzmann) in Grad’s method of moments is presented. The method is extremely powerful, easy to program and allows the derivation of balance equations to very high moments (limited only by computer resources). For sake of demonstration the method is applied to a simple case: the one-dimensional stationary granular gas under gravity. The method should find applications in the field of rarefied gases, as well. Questions of convergence, closure are beyond the scope of this article.},
author = {Serero, Dan and Noskowicz, S. H.},
faupublication = {yes},
journal = {Mathematical Modelling of Natural Phenomena},
pages = {151 - 174},
peerreviewed = {Yes},
title = {{Application} of the {Method} of {Generating} {Functions} to the {Derivation} of {Grad}’s {N}-{Moment} {Equations} for a {Granular} {Gas}},
volume = {6},
year = {2011}
}
@article{faucris.123992484,
abstract = {Molecular dynamics algorithms for systems of particles interacting through discrete or "hard" potentials are fundamentally different to the methods for continuous or "soft" potential systems. Although many software packages have been developed for continuous potential systems, software for discrete potential systems based on event-driven algorithms are relatively scarce and specialized. We present DynamO, a general event-driven simulation package, which displays the optimal O(N) asymptotic scaling of the computational cost with the number of particles N, rather than the O(N log N) scaling found in most standard algorithms. DynamO provides reference implementations of the best available event-driven algorithms. These techniques allow the rapid simulation of both complex and large (>10 particles) systems for long times. The performance of the program is benchmarked for elastic hard sphere systems, homogeneous cooling and sheared inelastic hard spheres, and equilibrium Lennard-Jones fluids. This software and its documentation are distributed under the GNU General Public license and can be freely downloaded from. Copyright © 2011 Wiley Periodicals, Inc.},
author = {Bannerman, Marcus and Lue, Leo and Sargant, R.},
doi = {10.1002/jcc.21915},
faupublication = {yes},
journal = {Journal of Computational Chemistry},
keywords = {discontinuous potentials; event-driven simulation; hard spheres; molecular dynamics; square-well potential},
pages = {3329-3338},
peerreviewed = {Yes},
title = {{DynamO}: {A} free {O}({N}) general event-driven molecular dynamics simulator},
volume = {32},
year = {2011}
}
@article{faucris.119186804,
abstract = {With the assumption of a linear-dashpot interaction force, the coefficient of restitution, ε (k, γ), can be computed as a function of the elastic and dissipative material constants, k and γ by integrating Newton's equation of motion for an isolated pair of colliding particles. If we require further that the particles interact exclusively repulsive, which is a common assumption in granular systems, we obtain an expression ε (k, γ) which differs even qualitatively from the known result ε (k, γ). The expression ε (k, γ) allows to relate Molecular Dynamics simulations to event-driven Molecular Dynamics for a widely used collision model. © 2007 Springer-Verlag.},
author = {Schwager, Thomas and Pöschel, Thorsten},
doi = {10.1007/s10035-007-0065-z},
faupublication = {no},
journal = {Granular Matter},
keywords = {Coefficient of restitution; Particle collisions},
pages = {465-469},
peerreviewed = {Yes},
title = {{Coefficient} of restitution and linear-dashpot model revisited},
volume = {9},
year = {2007}
}
@article{faucris.122091244,
abstract = {A method of modifying the roughness of soda-lime glass spheres is presented, with the purpose of tuning interparticle friction. The effect of chemical etching on the surface topography and the bulk frictional properties of grains are systematically investigated. The surface roughness of the grains is measured using white-light interferometry and characterized by the lateral and vertical roughness length scales. The underwater angle of repose is measured to characterize the bulk frictional behavior. We observe that the coefficient of friction depends on the vertical roughness length scale.},
author = {Schröter, Matthias and Utermann, Sonia and Aurin, Philipp and Benderoth, Markus and Fischer, Cornelius},
doi = {10.1103/PhysRevE.84.031306},
faupublication = {no},
journal = {Physical Review E - Statistical, Nonlinear, and Soft Matter Physics},
peerreviewed = {unknown},
title = {{Tailoring} the frictional properties of granular media},
volume = {84},
year = {2011}
}
@article{faucris.109909184,
abstract = {We perform a dimension analysis for colliding viscoelastic spheres to show that the coefficient of normal restitution ε depends on the impact velocity g as ε=1-γg+γg+ ⋯, in accordance with recent findings. We develop a simple theory to find explicit expressions for coefficients γ and γ. Using these and few next expansion coefficients for ε(g) we construct a Padé approximation for this function which may be used for a wide range of impact velocities where the concept of the viscoelastic collision is valid. The obtained expression reproduces quite accurately the existing experimental dependence ε(g) for ice particles.},
author = {Ramirez, Rosa and Pöschel, Thorsten and Brilliantov, Nikolai and Schwager, Thomas},
doi = {10.1103/PhysRevE.60.4465},
faupublication = {no},
journal = {Physical Review E},
pages = {4465-4472},
peerreviewed = {Yes},
title = {{Coefficient} of restitution of colliding viscoelastic spheres},
volume = {60},
year = {1999}
}
@article{faucris.123963444,
abstract = {feedback.

Such a laser roughly displays three operational intervals of stability, which we characterize using highresolution

stability charts and a video. Contrary to current belief, we find delays smaller than ∼1 μs to strongly

“clean complexity,” namely, to prevent chaos and periodic pulsations with many spikes. In contrast, complex

pulsations and chaos are significantly enhanced for τ > 1 μs. In this range, one finds a complex alternation of

periodic and chaotic phases, which are sensitive to the delay duration. © 2016 Optical Society of America},
author = {Junges, Leandro and Gallas, Jason},
doi = {10.1364/JOSAB.33.000373},
faupublication = {yes},
journal = {Journal of the Optical Society of America},
keywords = {Lasers, carbn dioxide, nonlinear optics, Instabilities and chaos},
pages = {373-381},
peerreviewed = {Yes},
title = {{Impact} of delayed feedback of arbitrary duration in self-pulsations of a {CO2} laser},
volume = {33},
year = {2016}
}
@incollection{faucris.218986067,
abstract = {Matter appears on our planet, in the solar system and in the rest of Universe in rather different forms.},
author = {Ebeling, Werner and Pöschel, Thorsten},
booktitle = {Lectures on Quantum Statistics},
doi = {10.1007/978-3-030-05734-3_1},
faupublication = {yes},
isbn = {978-3-030-05734-3},
note = {CRIS-Team Scopus Importer:2019-05-28},
pages = {1-17},
peerreviewed = {unknown},
publisher = {Springer Verlag},
series = {Lecture Notes in Physics},
title = {{Basic} physics of gases and plasmas},
volume = {953},
year = {2019}
}
@article{faucris.122140084,
abstract = {We report numerical evidence showing that periodic oscillations can produce unexpected and wide-ranging zig-zag parameter networks embedded in chaos in the control space of nonlinear systems. Such networks interconnect shrimplike windows of stable oscillations and are illustrated here for a tunnel diode, for an erbium-doped fiber-ring laser, and for the Hénon map, a proxy of certain CO lasers. Networks in maps can be studied without the need for solving differential equations. Tuning parameters along zig-zag networks allows one to continuously modify wave patterns without changing their chaotic or periodic nature. In addition, we report convenient parameter ranges where such networks can be detected experimentally. © 2013 American Physical Society.},
author = {Francke, Ricardo and Pöschel, Thorsten and Gallas, Jason},
doi = {10.1103/PhysRevE.87.042907},
faupublication = {yes},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Zig}-zag networks of self-excited periodic oscillations in a tunnel diode and a fiber-ring laser},
volume = {87},
year = {2013}
}
@article{faucris.119713044,
author = {Pöschel, Thorsten and Wolf, Dietrich},
faupublication = {yes},
journal = {Granular Matter},
peerreviewed = {Yes},
title = {{Granular} {Matter} - special edition},
volume = {14},
year = {2012}
}
@article{faucris.114391464,
abstract = {In particulate soft matter systems the average number of contacts \textitZ of a particle is an important predictor of the mechanical properties of the system. Using x-ray tomography, we analyze packings of frictional, oblate ellipsoids of various aspect ratios α, prepared at different global volume fractions \textit{ϕ}\textsubscript{\textitg}}. We find that \textitZ is a monotonically increasing function of \textit{ϕ}\textsubscript{\textitg}} for all \textit{α}. We demonstrate that this functional dependence can be explained by a local analysis where each particle is described by its local volume fraction \textit{ϕ}\textsubscript{\textitl}}\textsubscript{ }computed from a Voronoi tessellation. \textitZ can be expressed as an integral over all values of \textit{ϕ}\textsubscript{\textitl}}: Z(\textit{ϕ}\textsubscript{\textitg}},\textit{α},\textitX)=∫Z\textsubscript{\textitl}}(\textit{ϕ}\textsubscript{\textitl}},\textit{α},\textitX)\textitP(\textit{ϕ}\textsubscript{\textitl}}|\textit{ϕ}\textsubscript{\textitg}})\textit{dϕ}\textsubscript{\textitl}}. The local contact number function\textit{ Z}\textsubscript{\textitl}}(\textit{ϕ}\textsubscript{\textitl}},\textit{α},\textitX) describes the relevant physics in term of locally defined variables only, including possible higher order terms\textit{ X}. The conditional probability P(\textit{ϕ}\textsubscript{\textitl}}|\textit{ϕ}\textsubscript{\textitg}}) to find a specific value of \textit{ϕ}\textsubscript{\textitl}} given a global packing fraction \textit{ϕ}\textsubscript{\textitg}} is found to be independent of \textit{α} and \textitX. Our results demonstrate that for frictional particles a local approach is not only a theoretical requirement but also feasible.},
author = {Schaller, Fabian and Neudecker, Max and Saadatfar, Mohammad and Delaney, Gary and Schröder-Turk, Gerd and Schröter, Matthias},
doi = {10.1103/PhysRevLett.114.158001},
faupublication = {yes},
journal = {Physical Review Letters},
pages = {158001},
peerreviewed = {Yes},
title = {{Local} {Origin} of {Global} {Contact} {Numbers} in {Frictional} {Ellipsoid} {Packings}},
volume = {114},
year = {2015}
}
@article{faucris.119402404,
abstract = {

The development of reliable strategies to optimize part production in additive manufacturing technologies hinges, to a large extent, on the quantitative understanding of the mechanical behavior of the powder particles during the application process. Since it is difficult to acquire this understanding based on experiments alone, a particle- based numerical tool for the simulation of powder application is required. In the present work, we develop such a numerical tool and apply it to investigate the characteristics of the powder layer de posited onto the part using a roller as the coating system. In our simulations, the complex geometric shapes of the powder particles are taken explicitly into account. Our results show that increasing the coating speed leads to an increase in the surface roughness of the powder bed, which is known to affect part quality. We also find that, surprisingly, powders with broader size distributions may lead to larger values of surface roughness as the smallest particles are most prone to form large agglomerates thus increasing the packing’s porosity. Moreover, we find that the load on the part may vary over an order of magnitude during the coating process owing to the strong inhomogeneity of inter-particle forces in the granular packing. Our numerical tool can be used to assist — and partially replace — experimental investigations of the flowability and packing behavior of different powder systems as a function of material and process parameters.

},
author = {Ribeiro Parteli, Eric Josef and Pöschel, Thorsten},
doi = {10.1051/epjconf/201714015013},
faupublication = {yes},
journal = {EPJ Web of Conferences},
peerreviewed = {unknown},
title = {{Particle}-based simulations of powder coating in additive manufacturing suggest increase in powder bed roughness with coating speed},
volume = {140},
year = {2017}
}
@inproceedings{faucris.122077164,
abstract = {We investigate collective dissipative properties of vibrated granular materials by means of molecular dynamics simulations. The rate of energy loss indicates three different phases in the amplitude-frequency plane of the external forcing, namely solid, convective and gas-like regimes. The behavior of the effective damping decrement is consistent with the glassy nature of granular solids. The gas-like regime is most promising for practical applications.},
author = {Salueña, Clara and Esipov, Sergei E. and Pöschel, Thorsten and Simonian, Stephan S.},
booktitle = {Smart Structures and Materials 2002: Damping and Isolation},
doi = {10.1117/12.310696},
editor = {Agnes G.S.},
faupublication = {no},
keywords = {Damping regimes; Molecular Dynamics simulations},
pages = {23-29},
title = {{Dissipative} properties of granular ensembles},
venue = {San Diego, CA},
volume = {3327},
year = {1998}
}
@incollection{faucris.119941624,
abstract = {An introduction is presented to numerical methods, by which the behavior of complex metallic alloys can be simulated. We primarily consider the molecular dynamics (MD) technique as implemented in our software package IMD, where Newton’s equations of motion are solved for all atoms in a solid. After a short discourse on integration algorithms, some possible types of interactions are addressed. Already simple model potentials, as for example the Lennard-Jones-Gauss potential, can give rise to complex structures, where the characteristic length scales of the order by far exceed the range of the pair interaction. Realistic interactions are modelled by highly parametrized effective potentials, like the EAM (Embedded Atom Method) potential. Our program potfit allows to fit the parameters such that data from experiment or from ab-initio calculations are well reproduced. Several applications of the methods are outlined, notably the simulation of aluminium diffusion in quasicrystalline d-Al-Ni-Co, the computation of the phonon dispersion via the dynamical structure factor of MgZn2, the propagation of cracks in NbCr2, and an order-disorder phase transition in CaCd6. },
author = {Trebin, Hans-Rainer and Brommer, Peter and Engel, Michael and Gähler, Franz and Hocker, Stephen and Roth, Johannes and Rösch, Frohmut},
booktitle = {Properties and Applications of Complex Intermetallics},
faupublication = {no},
isbn = {978-981-4261-63-0},
pages = {293-330},
peerreviewed = {unknown},
publisher = {World Scientific},
series = {Book Series on Complex Metallic Alloys},
title = {{Simulating} structure and physical properties of complex metallic alloys},
volume = {2},
year = {2009}
}
@article{faucris.118257524,
abstract = {With the assumption of viscoelastic particle deformation, it is demonstrated that naive scaling modifies the properties of granular systems such that the original system and the scaled system might reveal quite different dynamic properties. To guarantee equivalent dynamical properties of the original and the scaled systems, material properties are modified in accordance with the scaling factor. For demonstration purposes, an example is given where the dynamics of a granular system changes significantly with system size.},
author = {Pöschel, Thorsten and Salueña, Clara and Schwager, Thomas},
doi = {10.1103/PhysRevE.64.011308},
faupublication = {no},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Scaling} properties of granular materials},
volume = {64},
year = {2001}
}
@article{faucris.122572384,
abstract = {
Learning how to assemble inorganic nanoparticles into

ordered lattices may prove to be important for applications,

such as, electronics, photonics, and catalysis.

[1]

Indeed, theo-

retical studies have shown that certain types of crystalline

arrays of nanoparticles could potentially be used to generate

photonic band-gap materials, negative index materials, and

metamaterials at visible and infrared length scales.

[2,3]

The

vast majority of work in this area has focused on the assembly

of spherical particles. However, anisotropic nanoparticles,

which display rich assembly behavior owing to their reduced

symmetry, and have unique physical properties that can be

engineered by controlling interparticle spacing and orienta-

tion, may provide access to even more interesting materi-

als.

[4–8]

Moreover, they require design rules for predicting the

way such nanoparticles can assemble and the types of

structures that may be realized. The rapidly expanding library

of available anisotropic nanoparticle building blocks provides

exciting new opportunities to study colloidal assembly as

a function of particle shape.

[9–11]

},
author = {Engel, Michael and Young, Kaylie L. and Personick, Michelle L. and Damasceno, Pablo F. and Barnaby, Stacey N. and Bleher, Reiner and Li, Tao and Glotzer, Sharon C. and Lee, Byeongdu and Mirkin, Chad A.},
doi = {10.1002/anie.201306009},
faupublication = {no},
journal = {Angewandte Chemie-International Edition},
keywords = {depletion forces;entropy;nanomaterials;nanoparticles;surfactants},
pages = {13980-13984},
peerreviewed = {Yes},
title = {{A} {Directional} {Entropic} {Force} {Approach} to {Assemble} {Anisotropic} {Nanoparticles} into {Superlattices}},
volume = {52},
year = {2013}
}
@article{faucris.116703444,
abstract = {Over a century of research into the origin of turbulence in wall-bounded shear flows has resulted in a puzzling picture in which turbulence appears in a variety of different states competing with laminar background flow. At moderate flow speeds, turbulence is confined to localized patches; it is only at higher speeds that the entire flow becomes turbulent. The origin of the different states encountered during this transition, the front dynamics of the turbulent regions and the transformation to full turbulence have yet to be explained. By combining experiments, theory and computer simulations, here we uncover a bifurcation scenario that explains the transformation to fully turbulent pipe flow and describe the front dynamics of the different states encountered in the process. Key to resolving this problem is the interpretation of the flow as a bistable system with nonlinear propagation (advection) of turbulent fronts. These findings bridge the gap between our understanding of the onset of turbulence and fully turbulent flows.},
author = {Song, Baofang and Barkley, Dwight and Mukund, Vasudevan and Lemoult, Grégoire and Avila Canellas, Marc and Hof, Björn},
doi = {10.1038/nature15701},
faupublication = {yes},
journal = {Nature},
pages = {550-553},
peerreviewed = {unknown},
title = {{The} rise of fully turbulent flow},
volume = {526},
year = {2015}
}
@article{faucris.109027644,
abstract = {In [1] the rotational frequency of a single Vibrot was incorrectly plotted as a function

of the excitation amplitude A. Instead the figure shows the data in dependence of the

dimensionless acceleration Γ= A(2πƒD)2/g, where g is the gravitational acceleration.

Only in the case of ƒD = 50 Hz A = 0.13 mm corresponds to Γ = 1.3 g and vice versa.

The corresponding paragraph of the original manuscript must then be replaced by the

following: „Figure 4 shows ϖ vs. ƒD for two different values of the dimensionless

acceleration Γ = A(2πƒD)2/g. For a low Γ the particle performs slow rotation where

ƒD depends non-monotonously on the frequency characterized by a minimum at ƒD = 50

Hz. For large Γ, we observe slow rotation at low frequency and tumbling motion for

ƒD ≥ 30 Hz, where the rotational velocity decreases with increasing ƒD.“ The

corrected version of the plot is shown in Fig. 4.},
author = {Scholz, Christian and Pöschel, Thorsten},
faupublication = {yes},
journal = {Revista Cubana de Fisica },
peerreviewed = {unknown},
title = {{Erratum} to: {Actively} {Rotating} {Granular} {Particles} {Manufactured} by {Rapid} {Prototyping}},
volume = {33},
year = {2016}
}
@article{faucris.109954064,
abstract = {A modified single-stage low pressure impactor is described to measure the coefficient of normal restitution e for nanoparticles. The device is analysed numerically using CFD, and the gas flow inside the structured impaction plate is studied. A formula for the calculation of e is derived and first measurements of e for spherical silver particles are presented together with numerical data obtained from force-based molecular dynamics simulations. Furthermore, the simulation data for e and the sticking probability are investigated in detail for the elastic, and partly for the plastic impaction regime. Particle collisions are of great importance for the modeling of fundamental processes in a wide range of interests. So far it was not possible to determine the coefficient of restitution for nanoparticles experimentally. Here, a new measurement technique is described. The results are compared to and extended by a numerical study for detailed analysis. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.},
author = {Schöner, Christian and Rennecke, Stephan and Weber, Alfred P. and Pöschel, Thorsten},
doi = {10.1002/cite.201300132},
faupublication = {yes},
journal = {Chemie Ingenieur Technik},
keywords = {Coefficient of restitution; Impaction; Molecular dynamics; Nanoparticle; Product design; Rebound},
pages = {365-374},
peerreviewed = {Yes},
title = {{Introduction} of a new technique to measure the coefficient of restitution for nanoparticles},
volume = {86},
year = {2014}
}
@article{faucris.111640584,
author = {Amon, Axelle and Born, Philip and Daniels, Karin and Dijksman, Joshua and Huang, Kai and Parker, David and Schröter, Matthias and Stannarius, Ralf and Wierschem, Andreas},
doi = {10.1063/1.4983052},
faupublication = {yes},
journal = {Review of Scientific Instruments},
note = {UnivIS-Import:2018-02-22:Pub.2017.tech.ITC.stmmec.focuso},
peerreviewed = {Yes},
title = {{Focus} on imaging methods in granular physics},
volume = {88},
year = {2017}
}
@article{faucris.122096304,
abstract = {We measure the two-point correlation of free Voronoi volumes in binary disc packings, where the packing fraction phi(avg) ranges from 0.8175 to 0.8380. We observe short-ranged correlations over the whole range of phi(avg) and anticorrelations for phi(avg) > 0.8277. The spatial extent of the anticorrelation increases with phi(avg) while the position of the maximum of the anticorrelation and the extent of the positive correlation shrink with phi(avg). We conjecture that the onset of anticorrelation corresponds to dilatancy onset in this system. Copyright (C) EPLA, 2012},
author = {Schröter, Matthias and Zhao, Song-Chuan and Sidle, Stacy and Swinney, Harry L.},
doi = {10.1209/0295-5075/97/34004},
faupublication = {no},
journal = {EPL - Europhysics Letters},
peerreviewed = {Yes},
title = {{Correlation} between {Voronoi} volumes in disc packings},
volume = {97},
year = {2012}
}
@article{faucris.122866524,
abstract = {The dynamics of quasicrystals is more complicated than the dynamics of periodic solids and difficult to study in experiments. Here, we investigate a decagonal and a dodecagonal quasicrystal using molecular dynamics simulations of the Lennard-Jones-Gauss interaction system. We observe that the short-time dynamics is dominated by stochastic particle motion, so-called phason flips, which can be either single-particle jumps or correlated ringlike multi-particle moves. Over long times, the flip mechanism is efficient in reordering the quasicrystals and can generate diffusion. The temperature dependence of diffusion is described by an Arrhenius law. We also study the spatial distribution and correlation of mobile particles by analyzing the dynamic propensity.},
author = {Engel, Michael and Trebin, Hans-Rainer and Umezaki, Masahiro and Odagaki, Takashi},
doi = {10.1103/PhysRevB.82.134206},
faupublication = {no},
journal = {Physical Review B},
peerreviewed = {Yes},
title = {{Dynamics} of particle flips in two-dimensional quasicrystals},
volume = {82},
year = {2010}
}
@article{faucris.213224498,
abstract = {Self-assembly of individual building blocks into highly ordered structures, analogous to spontaneous growth of crystals from atoms, is a promising approach to realize the collective properties of nanocrystals. Yet the ability to reliably produce macroscopic assemblies is unavailable and key factors determining assembly quality/yield are not understood. Here we report the formation of highly ordered superlattice films, with single crystalline domains of up to half a millimetre in two dimensions and thickness of up to several microns from nanocrystals with tens of nanometres in diameter. Combining experimental and computational results for gold nanocrystals in the shapes of spheres, cubes, octahedra and rhombic dodecahedra, we investigate the entire self-assembly process from disordered suspensions to large-scale ordered superlattices induced by nanocrystal sedimentation and eventual solvent evaporation. Our findings reveal that the ultimate coherence length of superlattices strongly depends on nanocrystal shape. Factors inhibiting the formation of high-quality large-scale superlattices are explored in detail.},
author = {Gong, Jianxiao and Newman, Richmond S. and Engel, Michael and Zhao, Man and Bian, Fenggang and Glotzer, Sharon C. and Tang, Zhiyong},
doi = {10.1038/ncomms14038},
faupublication = {no},
journal = {Nature Communications},
note = {EAM Import::2019-03-13},
peerreviewed = {Yes},
title = {{Shape}-dependent ordering of gold nanocrystals into large-scale superlattices},
volume = {8},
year = {2017}
}
@inproceedings{faucris.109844724,
abstract = {In this paper an algorithm is described which combines the efficiency of event-driven Molecular-Dynamics (eMD) and the physical correctness of force-based Molecular-Dynamics (MD) for dilute granular systems of frictionless spheres. © 2013 AIP Publishing LL},
author = {Pöschel, Thorsten and Müller, Patric},
booktitle = {7th International Conference on Micromechanics of Granular Media: Powders and Grains 2013},
doi = {10.1063/1.4811889},
faupublication = {yes},
isbn = {9780735411661},
keywords = {event-driven Molecular-Dynamics; granular Gases; hard-sphere model; Molecular-Dynamics},
pages = {149-152},
title = {{Event}-driven {DEM} of soft spheres},
venue = {Sydney, NSW},
volume = {1542},
year = {2013}
}
@article{faucris.110024464,
abstract = {The static as well as the dynamic behavior of granular material are determined by dynamic and static friction. There are well known methods to inlcude static friction in molecular dynamics simulations using scarcely understood forces. We propose an ansatz based on the geometrical shape of nonspherical particles which does not involve an explicit expression for static friction. It is shown that the simulations based on this model are close to experimental results. © 1993 The American Physical Society.},
author = {Pöschel, Thorsten and Buchholtz, Volkhard},
doi = {10.1103/PhysRevLett.71.3963},
faupublication = {no},
journal = {Physical Review Letters},
pages = {3963-3966},
peerreviewed = {Yes},
title = {{Static} friction phenomena in granular materials: {Coulomb} law versus particle geometry},
volume = {71},
year = {1993}
}
@article{faucris.109106844,
abstract = {This paper reports a detailed numerical investigation of the geometrical and structural properties of three-dimensional heaps of particles. Our goal is the characterization of very large heaps produced by ballistic deposition from extended circular dropping areas. First, we provide an in-depth study of the formation of monodisperse heaps of particles. We find very large heaps to contain three new geometrical characteristics: they may display two external angles of repose, one internal angle of repose, and four distinct packing fraction (density) regions. Such features are found to be directly connected with the size of the dropping zone. We derive a differential equation describing the boundary of an unexpected triangular packing fraction zone formed under the dropping area.We investigate the impact that noise during the deposition has on the final heap structure. In addition, we perform two complementary experiments designed to test the robustness of the novel features found. The first experiment considers changes due to polydispersity. The second checks what happens when letting the extended dropping zone to become a point-like source of particles, the more common type of source.},
author = {Gallas, Jason and Pöschel, Thorsten and Topic, Nikola},
doi = {10.1080/14786435.2013.797618},
faupublication = {yes},
journal = {Philosophical Magazine},
pages = {4090-4107},
peerreviewed = {unknown},
title = {{Characteristics} of large threedimensional heaps of particles produced by ballistic deposition from extended sources},
volume = {93},
year = {2013}
}
@article{faucris.106293044,
abstract = {Systems of granular rotors (Vibrots), that is, small devices that convert linear

vibrational motion into rotation by frictional impact, are of scientific interest

since they could reveal various types of collective behavior. Looking at an

isolated Vibrot, we note at least two dierent dynamical modes, depending on the

parameters of the vibrational driving. By means of Finite Element simulations,

we reveal the driving mechanism for both cases which may be correspondingly

identified as ratcheting and tumbling. The transition between both modes

resembles period doubling in certain bouncing ball problems leading eventually

to chaotic motion in such systems.},
author = {Scholz, Christian and Dsilva, Sean and Pöschel, Thorsten},
doi = {10.1088/1367-2630/18/12/123001},
faupublication = {yes},
journal = {New Journal of Physics},
peerreviewed = {Yes},
title = {{Ratcheting} and tumbling motion of {Vibrots}},
volume = {18},
year = {2016}
}
@article{faucris.122587124,
abstract = {In a granular gas of rough particles the spin of a grain is correlated with its linear velocity. We develop an analytical theory to account for these correlations and compare its predictions to numerical simulations, using Direct Simulation Monte Carlo as well as Molecular Dynamics. The system is shown to relax from an arbitrary initial state to a steady-state, which is characterized by time-independent, finite correlations of spin and linear velocity. The latter are analyzed systematically for a wide range of system parameters, including the coefficients of tangential and normal restitution as well as the moment of inertia of the particles. For most parameter values the axis of rotation and the direction of linear momentum are perpendicular like in a sliced tennis ball, while parallel orientation, like in a rifled bullet, occurs only for a small range of parameters. The limit of smooth spheres is singular: any arbitrarily small roughness unavoidably causes significant translation-rotation correlations, whereas for perfectly smooth spheres the rotational degrees of freedom are completely decoupled from the dynamic evolution of the gas. © 2009 EDP Sciences and Springer.},
author = {Kranz, W. T. and Brilliantov, Nikolai V. and Pöschel, Thorsten and Zippelius, A.},
doi = {10.1140/epjst/e2010-01196-0},
faupublication = {yes},
journal = {European Physical Journal-Special Topics},
pages = {91-111},
peerreviewed = {Yes},
title = {{Correlation} of spin and velocity in the homogeneous cooling state of a granular gas of rough particles},
volume = {179},
year = {2009}
}
@article{faucris.115463744,
abstract = {We report a five-component autonomous chaotic oscillator

of jerky type, hitherto the simplest of its kind, using only

one operational amplifier. The key component of the circuit is a

junction field-effect transistor operating in its triode region, which

provides a nonlinear resistor of antisymmetrical current–voltage

characteristic, emulating a Colpitts-like chaotic circuit. We describe

the experimental results illustrating the dynamical behavior

of the circuit. In addition, we report numerical simulations of

a model of the circuit which display good agreement with our

measurements.},
author = {Tchitnga, Robert and Nguazon, Tekou and Louodop Fotso,, Patrick H. and Gallas, Jason},
faupublication = {yes},
journal = {IEEE Transactions on Circuits and Systems Ii-Express Briefs},
keywords = {Bifurcations, jerk oscillator, junction field-effect transistor (JFET), piecewise (PW) nonlinearity (NLT), simplest chaotic circuit I},
peerreviewed = {Yes},
title = {{Chaos} in a {Single} {Op}-{Amp}–{Based} {Jerk} {Circuit}: {Experiments} and {Simulations}},
volume = {Vol. 63},
year = {2016}
}
@incollection{faucris.116712904,
abstract = {In order to study the behaviour of fluidized granular material experimentally and numerically, we propose to investigate pattern-forming processes, because they can be easily observed and quantitatively characterized. We report measurements on five such systems, namely pattern formation of granular material i) by segregation, under the influence of ii) linear horizontal and iii) circular horizontal vibration, iv) water shear flow, and in v) a sedimenting suspension},
address = {Berlin},
author = {Rehberg, Ingo and Scherer, Michael A. and Schröter, Matthias and Betat, André and Dury, Christian M. and Ristow, Gerald H. and Straßburger, Gunther},
booktitle = {Evolution of Spontaneous Structures in Dissipative Continuous Systems},
editor = {Busse FH, Müller, SC},
faupublication = {no},
isbn = {978-3-540-49537-6},
pages = {495 - 545},
peerreviewed = {unknown},
publisher = {Springer},
title = {{Formation} of {Patterns} in {Granular} {Materials}},
volume = {495},
year = {1998}
}
@article{faucris.114680544,
abstract = {Granular heaps of particles created by deposition of mono-disperse particles raining from an extended

source of finite size are characterized by a non-homogeneous field of density. It was speculated that this

inhomogeneity is due to the transient shape of the sediment during the process of construction of the

heap, thus reflecting the history of the creation of the heap. By comparison of structural characteristics of

the heap with sediments created on top of inclined planes exploiting the method of Minkowski tensors,

we provide further evidence to support this hypothesis. Moreover, for the case of sediments generated by

homogeneous rain on surfaces, we provide relationships between the inclination of the surface and the

Minkowski measures characterizing the isotropy of local particle environments.},
author = {Topic, Nikola and Schaller, Fabian and Schröder-Turk, Gerd and Pöschel, Thorsten},
doi = {10.1039/c5sm03114a},
faupublication = {yes},
journal = {Soft Matter},
peerreviewed = {Yes},
title = {{The} microscopic structure of mono-disperse granular heaps and sediments of particles on inclined surfaces},
year = {2016}
}
@article{faucris.217787917,
abstract = {An important task in the simulation of hard spheres and other hard particles is structure prediction via equilibration. Event-driven molecular dynamics is efficient because its Newtonian dynamics equilibrates fluctuations with the speed of sound. Monte Carlo simulation is efficient if performed with correlated position updates in event chains. Here, we combine the core concepts of molecular dynamics and event chains into a new algorithm involving Newtonian event chains. Measurements of the diffusion coefficient, nucleation rate, and melting speed demonstrate that Newtonian event chains outperform other algorithms. Newtonian event chains scale well to large systems and can be extended to anisotropic hard particles without approximations.},
author = {Klement, Marco and Engel, Michael},
doi = {10.1063/1.5090882},
faupublication = {yes},
journal = {Journal of Chemical Physics},
note = {CRIS-Team Scopus Importer:2019-05-17},
peerreviewed = {Yes},
title = {{Efficient} equilibration of hard spheres with {Newtonian} event chains},
volume = {150},
year = {2019}
}
@article{faucris.123094884,
abstract = {Spherical micelles can aggregate into highly organized structures. New micelle arrangements mimic known atomic crystals, both periodic and aperiodic, and provide evidence for a material with 18-fold rotational symmetry.},
author = {Glotzer, Sharon C. and Engel, Michael},
doi = {10.1038/471309a},
faupublication = {no},
journal = {Nature},
pages = {309-310},
peerreviewed = {unknown},
title = {{News} & {Views}: {Complex} order in soft matter},
volume = {471},
year = {2011}
}
@article{faucris.124007224,
abstract = {In thin-layer electrodeposition the dissipated electrical energy leads to a substantial heating of the ion solution. We measured the resulting temperature field by means of an infrared camera. The properties of the temperature field correspond closely with the development of the concentration field. In particular, we find that the thermal gradients at the electrodes act similar to a weak additional driving force to the convection rolls driven by concentration gradients.},
author = {Schröter, Matthias and Claret, Josep and Kassner, Klaus and Rehberg, Ingo and Sagués, Francesc},
doi = {10.1103/PhysRevE.66.026307},
faupublication = {no},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Influence} of ohmic heating on the flow field in thin-layer electrodeposition},
volume = {66},
year = {2002}
}
@article{faucris.213079539,
abstract = {We report an algorithm to extract equations of motion for orbits of arbitrarily high periods generated by iteration of the Pincherle map, the operational kernel used in the so-called chaotic computers. The performance of the algorithm is illustrated explicitly by extracting expeditiously, among others, an orbit buried inside a polynomial cluster of equations with degree exceeding one billion, out of reach by ordinary brute-force factorization. Large polynomial clusters are responsible for the organization of the phase-space and knowledge of this organization requires decomposing such clusters.},
author = {Gallas, Jason},
doi = {10.1016/j.rinp.2016.08.005},
faupublication = {yes},
journal = {Results in Physics},
note = {EAM Import::2019-03-12},
pages = {561-567},
peerreviewed = {Yes},
title = {{Method} for extracting arbitrarily large orbital equations of the {Pincherle} map},
volume = {6},
year = {2016}
}
@article{faucris.107381824,
abstract = {The kinetic energy of a force-free granular gas decays monotonously due to inelastic collisions of the particles. For a homogeneous granular gas of identical particles, the corresponding decay of granular temperature is quantified by Haff’s law. Here, we report that for a granular gas of aggregating particles, the granular temperature does not necessarily decay but may even increase. Surprisingly, the increase of temperature is accompanied by the continuous loss of total gas energy. This stunning effect arises from a subtle interplay between decaying kinetic energy and gradual reduction of the number of degrees of freedom associated with the particles’ dynamics. We derive a set of kinetic equations of Smoluchowski type for the concentrations of aggregates of different sizes and their energies. We find scaling solutions to these equations and a condition for the aggregation mechanism predicting growth of temperature. Numerical direct simulation Monte Carlo results confirm the theoretical predictions.},
author = {Brilliantov, Nikolai and Formella, Arno and Pöschel, Thorsten},
doi = {10.1038/s41467-017-02803-7},
faupublication = {yes},
journal = {Nature Communications},
peerreviewed = {Yes},
title = {{Increasing} temperature of cooling granular gases},
volume = {9},
year = {2018}
}
@article{faucris.110034144,
abstract = {Collisions between granular particles are irreversible processes which cause dissipation of mechanical energy by fragmentation or heating of the colliders. The knowledge of these phenomena is essential for the understanding of the behaviour of complex systems of granular particles. We have developed a model for inelastic collisions of granular particles and calculated the velocity restitution coefficients, which describe all possible collisions in the system. The knowledge of these coefficients allows for event-driven many-particle simulations which cannot be performed in the frame of molecular dynamics. This approach has the advantage that very large particle numbers can be treated which are necessary for the understanding of intrinsic large-scale phenomena in granular systems.},
author = {Brilliantov, Nikolai and Spahn, Frank and Hertzsch, Jan-Martin and Pöschel, Thorsten},
doi = {10.1016/0378-4371(96)00099-4},
faupublication = {no},
journal = {Physica A-Statistical Mechanics and Its Applications},
pages = {417-424},
peerreviewed = {Yes},
title = {{The} collision of particles in granular systems},
volume = {231},
year = {1996}
}
@article{faucris.107382044,
abstract = {Biological organisms and artificial active particles self-organize into swarms and patterns. Open questions concern the design of emergent phenomena by choosing appropriate forms of activity and particle interactions. A particularly simple and versatile system are 3D-printed robots on a vibrating table that can perform self-propelled and self-spinning motion. Here we study a mixture of minimalistic clockwise and counter-clockwise rotating robots, called rotors. Our experiments show that rotors move collectively and exhibit super-diffusive interfacial motion and phase separate via spinodal decomposition. On long time scales, confinement favors symmetric demixing patterns. By mapping rotor motion on a Langevin equation with a constant driving torque and by comparison with computer simulations, we demonstrate that our macroscopic system is a form of active soft matter.},
author = {Scholz, Christian and Engel, Michael and Pöschel, Thorsten},
doi = {10.1038/s41467-018-03154-7},
faupublication = {yes},
journal = {Nature Communications},
pages = {931},
peerreviewed = {Yes},
title = {{Rotating} robots move collectively and self-organize.},
volume = {9},
year = {2018}
}
@article{faucris.121658724,
abstract = {Motivated by breakthroughs in the synthesis of faceted nano- and colloidal particles, as well as theoretical and computational studies of their packings, we investigate a family of truncated triangular bipyramids. We report dense periodic packings with small unit cells that were obtained via numerical and analytical optimization. The maximal packing fraction phi(max) changes continuously with the truncation parameter t. Eight distinct packings are identified based on discontinuities in the first and second derivatives of phi(max)(t). These packings differ in the number of particles in the fundamental domain (unit cell) and the type of contacts between the particles. In particular, we report two packings with four particles in the unit cell for which both phi(max)(t) and phi'(max)(t) are continuous and the discontinuity occurs in the second derivative only. In the self-assembly simulations that we perform for larger boxes with 2048 particles, only one out of eight packings is found to assemble. In addition, the degenerate quasicrystal reported previously for triangular bipyramids without truncation [Haji-Akbari et al., Phys. Rev. Lett. 107, 215702 (2011)] assembles for truncations as high as 0.45. The self-assembly propensities for the structures formed in the thermodynamic limit are explained using the isoperimetric quotient of the particles and the coordination number in the disordered fluid and in the assembled structure.},
author = {Engel, Michael and Haji-Akbari, Amir and Chen, Elizabeth R. and Glotzer, Sharon C.},
doi = {10.1103/PhysRevE.88.012127},
faupublication = {no},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Packing} and self-assembly of truncated triangular bipyramids},
volume = {88},
year = {2013}
}
@inproceedings{faucris.109845384,
author = {Engel, Michael},
booktitle = {APS March Meeting},
date = {2012-02-27/2012-03-02},
faupublication = {no},
peerreviewed = {unknown},
title = {{Towards} structural complexity with colloids},
venue = {Boston, MA},
year = {2012}
}
@article{faucris.109973424,
abstract = {The response of an oscillating granular damper to an initial perturbation is studied using experiments performed in microgravity and granular dynamics simulations. High-speed video and image processing techniques are used to extract experimental data. An inelastic hard sphere model is developed to perform simulations and the results are in excellent agreement with the experiments. In line with previous work, a linear decay of the amplitude is observed. Although this behavior is typical for a friction-damped oscillator, through simulation it is shown that this effect is still present even when friction forces are absent. A simple expression is developed which predicts the optimal damping conditions for a given amplitude and is independent of the oscillation frequency and particle inelasticities. © 2011 American Physical Society.},
author = {Bannerman, Marcus and Kollmer, Jonathan and Sack, Achim and Heckel, Michael and Müller, Patric and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.84.011301},
faupublication = {yes},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Movers} and shakers: {Granular} damping in microgravity},
volume = {84},
year = {2011}
}
@article{faucris.122794804,
abstract = {The self-assembling novel ordered structures with nanoparticles has recently received much attention. Here we use computer simulations to study a two-dimensional model system characterized by a simple isotropic interaction that could be realized with building blocks on the nanoscale. We find that the particles arrange themselves into hexagonal superstructures of twin boundaries whose superlattice vector can be tuned reversibly by changing the temperature. Thermodynamic stability is confirmed by calculating the free energy with a combination of thermodynamic integration and the Frenkel-Ladd method. Different contributions to the free energy difference are discussed.},
author = {Engel, Michael},
doi = {10.1103/PhysRevLett.106.095504},
faupublication = {no},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Entropic} {Stabilization} of {Tunable} {Planar} {Modulated} {Superstructures}},
volume = {106},
year = {2011}
}
@article{faucris.122138764,
abstract = {We consider the attenuation of the oscillation of a flat spring due to the action of a granular damper. The efficiency of the damper is quantified by evaluating the position of the oscillator as a function of time using a Hall effect based position sensor. Performing experiments for a large abundance of parameters under conditions of microgravity, we confirm a recent theory for granular damping (Kollmer et al. in New J Phys 15:093023, 2013) and show that the theory remains approximately valid even beyond the limits of its derivation.},
author = {Sack, Achim and Heckel, Michael and Kollmer, Jonathan and Pöschel, Thorsten},
doi = {10.1007/s10035-014-0539-8},
faupublication = {yes},
journal = {Granular Matter},
keywords = {Dissipation; Granular systems; Vibration damping},
pages = {73-82},
peerreviewed = {Yes},
title = {{Probing} the validity of an effective-one-particle description of granular dampers in microgravity},
volume = {17},
year = {2014}
}
@article{faucris.109988384,
abstract = {We investigate the transport of proteins inside the proteasome and propose an active-transport mechanism based on a spatially asymmetric interaction potential of peptide chains. The transport is driven by fluctuations which are always present in such systems. We compute the peptide-size-dependent transport rate which is essential for the functioning of the proteasome. In agreement with recent experiments, varying temperature changes the transport mechanism qualitatively. © EDP Sciences.},
author = {Zaikin, A. and Pöschel, Thorsten},
doi = {10.1209/epl/i2004-10426-8},
faupublication = {no},
journal = {EPL - Europhysics Letters},
pages = {725-731},
peerreviewed = {Yes},
title = {{Peptide}-size-dependent active transport in the proteasome},
volume = {69},
year = {2005}
}
@article{faucris.109920844,
abstract = {Assume in a sample of size M one finds M representatives of species i with i = 1 ⋯ N*. The normalized frequency p* ≡ M/M, based on the finite sample, may deviate considerably from the true probabilities p. We propose a method to infer rank-ordered true probabilities r from measured frequencies M. We show that the rank-ordered probabilities provide important informations on the system, e.g., the true number of species, the Shannon- and the Renyi-entropies. © EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2004.},
author = {Pöschel, Thorsten and Ebeling, Werner and Frömmel, Cornelius and Ramirez, Rosa},
doi = {10.1140/epje/e2004-00025-4},
faupublication = {no},
journal = {European Physical Journal E},
pages = {531-541},
peerreviewed = {Yes},
title = {{Correction} algorithm for finite sample statistics},
volume = {12},
year = {2003}
}
@inproceedings{faucris.119298784,
abstract = {Disordered packings of ellipsoidal particles are an important model for disordered granular matter. Here we report a way to determine the average contact number of ellipsoid packings from tomographic analysis. Tomographic images of jammed ellipsoid packings prepared by vertical shaking of loose configurations are recorded and the positions and orientations of the ellipsoids are reconstructed. The average contact number can be extracted from a contact number scaling (CNS) function. The size of the particles, that may vary due to production inaccuracies, can also be determined by this method.},
author = {Schröter, Matthias and Schaller, Fabian and Neudecker, Max and Saadatfar, Mohammad and Delaney, Gary and Mecke, Klaus and Schröder-Turk, Gerd},
date = {2013-07-08/2013-07-12},
doi = {10.1063/1.4811946},
faupublication = {yes},
keywords = {Granular matter;Ellipsoids;Tomography;Contact numbers},
month = {Jan},
pages = {377-380},
peerreviewed = {unknown},
publisher = {American Institute of Physics},
title = {{Tomographic} {Analysis} of {Jammed} {Ellipsoid} {Packings}},
venue = {Sydney, Australien},
volume = {1542},
year = {2013}
}
@article{faucris.109900604,
abstract = {The velocity distribution of a granular gas is analyzed in terms of the Sonine polynomials expansion. We derive an analytical expression for the third Sonine coefficient a. In contrast to frequently used assumptions this coefficient is of the same order of magnitude as the second Sonine coefficient a. For small inelasticity the theoretical result is in good agreement with numerical simulations. The next-order Sonine coefficients a, and a are determined numerically. While these coefficients are negligible for small dissipation, their magnitude grows rapidly with increasing inelasticity for 0 < ε ≲ 0.6. We conclude that this behavior of the Sonine coefficients manifests the breakdown of the Sonine polynomial expansion caused by the increasing impact of the overpopulated high-energy tail of the distribution function. © EDP Sciences.},
author = {Brilliantov, Nikolai V. and Pöschel, Thorsten},
doi = {10.1209/epl/i2005-10555-6},
faupublication = {no},
journal = {EPL - Europhysics Letters},
pages = {424-430},
peerreviewed = {Yes},
title = {{Breakdown} of the {Sonine} expansion for the velocity distribution of granular gases},
volume = {74},
year = {2006}
}
@article{faucris.114380464,
abstract = {We report an autonomous circuit containing periodicity hubs with surprisingly broad spirals. Knowledge of broad spirals is important because all presently known spirals are compressed along specific directions in parameter space making them difficult to study experimentally and theoretically. We characterize the performance of the circuit by computing stability diagrams for relevant sections of the control space. In addition, the alternation of chaotic and periodic spiral phases is contrasted with equivalent alternations obtained from an experimental implementation of the circuit.},
author = {Gallas, Jason and Cabeza, C. and Briozzo, Carlos A. and Garcia, Rodrigo and Freire, J. G. and Marti, Arturo C.},
doi = {10.1016/j.chaos.2013.04.001},
faupublication = {yes},
journal = {Chaos Solitons & Fractals},
pages = {59 - 65},
peerreviewed = {Yes},
title = {{Periodicity} hubs and wide spirals in a two-component autonomous electronic circuit},
volume = {52},
year = {2013}
}
@article{faucris.109627364,
abstract = {Although quasicrystals have been studied for 25 years, there are many open questions concerning their stability: What is the role of phason fluctuations? Do quasicrystals transform into periodic crystals at low temperature? If yes, by what mechanisms? We address these questions here for a simple two-dimensional model system, a monatomic decagonal quasicrystal, which is stabilized by the Lennard-Jones-Gauss potential in thermodynamic equilibrium. It is known to transform to the approximant Xi, when cooled below a critical temperature. We show that the decagonal phase is an entropically stabilized random tiling. By determining the average particle energy for a series of approximants, it is found that the approximant Xi is the one with lowest potential energy.},
author = {Engel, Michael and Trebin, Hans-Rainer},
doi = {10.1080/14786430802132548},
faupublication = {no},
journal = {Philosophical Magazine},
keywords = {phason flips;random tiling;approximants;molecular dynamic simulations;Monte-Carlo;phase transformations;quasicrystals},
month = {Jan},
pages = {1959-1965},
peerreviewed = {Yes},
title = {{Stability} of the decagonal quasicrystal in the {Lennard}-{Jones}-{Gauss} system},
volume = {88},
year = {2008}
}
@article{faucris.217940857,
abstract = {We present an enhanced version of our previously engineered MyoRobot system for reliable, versatile and automated investigations of skeletal muscle or linear polymer material (bio)mechanics. That previous version already replaced strenuous manual protocols to characterize muscle biomechanics properties and offered automated data analysis. Here, the system was further improved for precise control over experimental temperature and muscle single fiber sarcomere length. Moreover, it also now features the calculation of fiber cross-sectional area via on-the-fly optical diameter measurements using custom-engineered microscope optics. With this optical systems integration, the MyoRobot 2.0 allows to tailor a wealth of recordings for relevant physiological parameters to be sequentially executed in living single myofibers. Research questions include assessing temperature-dependent performance of active or passive biomechanics, or automated control over length-tension or length-velocity relations. The automatically obtained passive stress-strain relationships and elasticity modules are important parameters in (bio)material science. From the plethora of possible applications, we validated the improved MyoRobot 2.0 by assessing temperature-dependent myofibrillar Ca
^{2+}
sensitivity, passive axial compliance and Young's modulus. We report a Ca
^{2+}
desensitization and a narrowed dynamic range at higher temperatures in murine M. extensor digitorum longus single fibers. In addition, an increased axial mechanical compliance in single muscle fibers with Young's moduli between 40 - 60 kPa was found, compatible with reported physiological ranges. These applications demonstrate the robustness of our MyoRobot 2.0 for facilitated single muscle fiber biomechanics assessment.},
author = {Haug, Michael and Meyer, Charlotte and Reischl, Barbara and Prölß, Gerhard and Nübler, Stefanie and Schürmann, Sebastian and Schneidereit, Dominik and Heckel, Michael and Pöschel, Thorsten and Rupitsch, Stefan and Friedrich, Oliver},
doi = {10.1016/j.bios.2019.04.052},
faupublication = {yes},
journal = {Biosensors and Bioelectronics},
keywords = {Axial compliance; Biomechatronics; Biosensor; Ca2+ sensitivity; EDL; MyoRobot; Sarcomere length; Single fiber; Skeletal muscle; Temperature control; Young's modulus},
note = {CRIS-Team Scopus Importer:2019-05-21},
peerreviewed = {Yes},
title = {{MyoRobot} 2.0: {An} advanced biomechatronics platform for automated, environmentally controlled skeletal muscle single fiber biomechanics assessment employing inbuilt real-time optical imaging},
volume = {138},
year = {2019}
}
@article{faucris.110020284,
abstract = {We investigate the flow of granular material in a rotating cylinder numerically using molecular dynamics in two dimensions. The particles are described by a new model which allows to simulate geometrically complicated shaped grains. The results of the simulation agree significantly better with experiments than the results which are based on circular particles. © 1995.},
author = {Buchholtz, Volkhard and Pöschel, Thorsten and Tillemans, Hans-Jürgen},
doi = {10.1016/0378-4371(95)00045-9},
faupublication = {no},
journal = {Physica A-Statistical Mechanics and Its Applications},
pages = {199-212},
peerreviewed = {Yes},
title = {{Simulation} of rotating drum experiments using non-circular particles},
volume = {216},
year = {1995}
}
@inproceedings{faucris.122142944,
abstract = {We perform two-dimensional hydrodynamic simulations on a paradigmatic problem of granular dynamics, the Faraday instability, using two different approximations to the Navier-Stokes granular equations: the constitutive equations and kinetic coefficients derived from the assumption of vanishing inelasticity (Jenkins-Richman approach) obtained by solving the Enskog equation disks by means of Grad's method, and the ones obtained by solving the Enskog equation with the Chapman-Enskog method (Garzó-Dufty-Lutsko approach). The comparison reveals important qualitative and quantitative differences with respect to the hydrodynamic fields obtained by averaging results from particle simulations of the same system. © 2012 American Institute of Physics.},
author = {Almazán Torres, Lidia and Salueña, Clara and Garzó, Vicente and Carrillo, José A. and Pöschel, Thorsten},
booktitle = {28th International Symposium on Rarefied Gas Dynamics 2012, RGD 2012},
doi = {10.1063/1.4769650},
faupublication = {yes},
isbn = {9780735411159},
keywords = {Faraday instability; hydrodynamic simulations; molecular dynamics; Rapid granular flows},
pages = {993-1000},
title = {{Hydrodynamics} at the {Navier}-{Stokes} level applied to fast, transient, supersonic granular flows},
venue = {Zaragoza},
volume = {1501},
year = {2012}
}
@article{faucris.109180984,
abstract = {An inelastic hard ball bouncing repeatedly off the ground comes to rest in finite time by performing an infinite number of collisions. Similarly, a granular gas under the influence of external gravity, condenses at the bottom of the confinement due to inelastic collisions. By means of hydrodynamical simulations, we find that the condensation process of a granular gas reveals a similar dynamics as the bouncing ball. Our result is in agreement with both experiments and particle simulations, but disagrees with earlier simplified hydrodynamical description. Analyzing the result in detail, we find that the adequate modeling of pressure plays a key role in continuum modeling of granular matter.},
author = {Almazán Torres, Lidia and Serero, Dan and Salueña, Clara and Pöschel, Thorsten},
doi = {10.1088/1367-2630/aa5598},
faupublication = {yes},
journal = {New Journal of Physics},
month = {Jan},
peerreviewed = {Yes},
title = {{Energy} decay in a granular gas collapse},
volume = {19},
year = {2017}
}
@article{faucris.122384504,
abstract = {We report a degenerate quasicrystal in Monte Carlo simulations of hard triangular bipyramids each composed of two regular tetrahedra sharing a single face. The dodecagonal quasicrystal is similar to that recently reported for hard tetrahedra [Haji-Akbari et al., Nature (London) 462, 773 (2009)] but degenerate in the pairing of tetrahedra, and self-assembles at packing fractions above 54%. This notion of degeneracy differs from the degeneracy of a quasiperiodic random tiling arising through phason flips. Free energy calculations show that a triclinic crystal is preferred at high packing fractions.},
author = {Engel, Michael and Haji-Akbari, Amir and Glotzer, Sharon C.},
doi = {10.1103/PhysRevLett.107.215702},
faupublication = {no},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Degenerate} {Quasicrystal} of {Hard} {Triangular} {Bipyramids}},
volume = {107},
year = {2011}
}
@article{faucris.116685404,
abstract = {It has recently been established that quantum statistics can play a crucial role in quantum escape. Here we demonstrate that boundary conditions can be equally important-moreover, in certain cases, may lead to a complete suppression of the escape. Our results are exact and hold for arbitrarily many particles. Copyright (c) EPLA, 2012},
author = {Fregolente Mendes de Oliveira, Diego and Georgiou, Orestis and Gligoric, Goran and Lazarides, Achilleas and Bodyfelt, Joshua D. and Goussev, Arseni},
doi = {10.1209/0295-5075/100/20005},
faupublication = {yes},
journal = {EPL - Europhysics Letters},
peerreviewed = {Yes},
title = {{Influence} of boundary conditions on quantum escape},
volume = {100},
year = {2012}
}
@article{faucris.109947244,
abstract = {We investigate numerically the interaction of a stream of granular particles with a resting obstacle in two dimensions. For the case of high stream velocity we find that the force acting on the obstacle is proportional to the square of the stream velocity, the density and the obstacle size. This behaviour is equivalent to that of noninteracting hard spheres. For low stream velocity a gap between the obstacle and the incoming stream particles appears which is filled with granular gas of high temperature and low density. As soon as the gap appears the force does not depend on the square of velocity of the stream but the dependency obeys another law.},
author = {Buchholtz, Volkhard and Pöschel, Thorsten},
doi = {10.1007/PL00010908},
faupublication = {no},
journal = {Granular Matter},
pages = {33-41},
peerreviewed = {Yes},
title = {{Interaction} of a granular stream with an obstacle},
volume = {1},
year = {1998}
}
@phdthesis{faucris.123065844,
author = {Heckel, Michael},
faupublication = {yes},
keywords = {Granulare Dämpfer},
peerreviewed = {automatic},
school = {Friedrich-Alexander-Universität Erlangen-Nürnberg},
title = {{Granulare} {Dämpfer}},
url = {http://d-nb.info/1088423329},
year = {2015}
}
@article{faucris.109971664,
abstract = {We report the first three-dimensional molecular dynamics simulation of particle segregation by shaking. Two different containers are considered: one cylindrical and another with periodic boundary conditions. The dependence of the time evolution of a test particle inside the material is studied as a function of the shaking frequency and amplitude, damping coefficients, and dispersivity.},
author = {Gallas, Jason A. and Herrmann, Hans J. and Pöschel, Thorsten and Sokolowski, Stefan},
doi = {10.1007/BF02189239},
faupublication = {no},
journal = {Journal of Statistical Physics},
keywords = {Granular dynamics; Granular materials; Molecular dynamics; Size segregation; Whale effect},
pages = {443-450},
peerreviewed = {Yes},
title = {{Molecular} dynamics simulation of size segregation in three dimensions},
volume = {82},
year = {1996}
}
@incollection{faucris.109107724,
address = {New York},
author = {Ribeiro Parteli, Eric Josef},
booktitle = {Encyclopedia of Planetary Landforms},
editor = {Hargitai, H., Kereszturi, Ákos},
faupublication = {yes},
pages = {1-3},
peerreviewed = {unknown},
publisher = {Springer},
title = {{Dome} {Dune}},
year = {2014}
}
@article{faucris.114383104,
abstract = {We describe some remarkable *continuous deformations* which create and destroy peaks in periodic oscillations of the Mackey–Glass equation, a paradigmatic example of a delayed feedback system. Peak creation and destruction results in richer bifurcation diagrams which, in addition to the familiar branches arising from period-doubling and peak-adding bifurcations, may also display arbitrary combinations of doubling and adding, leading to highly complex mosaics of stability domains in control parameter space. In addition, we show that the onset of higher dimensionality does not alter the prevailing dynamics instantaneously and, remarkably, even may have no effect at all, a result that cannot be predicted analytically with standard methods.},
author = {Gallas, Jason A. and Gallas, Jason and Junges, Leandro},
doi = {10.1016/j.physleta.2012.05.022},
faupublication = {yes},
journal = {Physics Letters A},
pages = {2109--2116},
peerreviewed = {Yes},
title = {{Intricate} routes to chaos in the {Mackey}-{Glass} delayed feedback system},
volume = {376},
year = {2012}
}
@inproceedings{faucris.120956924,
author = {Engel, Michael},
booktitle = {11th International Conference on Quasicrystals},
date = {2010-06-13/2010-06-18},
faupublication = {no},
peerreviewed = {unknown},
title = {{Quasicrystalline} phase of densely packed tetrahedra},
venue = {Sapporo},
year = {2010}
}
@article{faucris.123588784,
abstract = {We study photonic band gap formation in two-dimensional high-refractive-index disordered materials where the dielectric structure is derived from packing disks in real and reciprocal space. Numerical calculations of the photonic density of states demonstrate the presence of a band gap for all polarizations in both cases. We find that the band gap width is controlled by the increase in positional correlation inducing short-range order and hyperuniformity concurrently. Our findings suggest that the optimization of short-range order, in particular the tailoring of Bragg scattering at the isotropic Brillouin zone, are of key importance for designing disordered PBG materials.},
author = {Luis S., Froufe-Pérez and Engel, Michael and Damasceno, Pablo F. and Muller, Nicolas and Haberko, Jakub and Glotzer, Sharon C. and Scheffold, Frank},
doi = {10.1103/PhysRevLett.117.053902},
faupublication = {no},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Role} of {Short}-{Range} {Order} and {Hyperuniformity} in the {Formation} of {Band} {Gaps} in {Disordered} {Photonic} {Materials}},
volume = {117},
year = {2016}
}
@article{faucris.106904424,
abstract = {
We consider electroconvection as the response of nematic liquid crystal to an external electric AC field, in the absence of free charge carriers. Previous experimental and theoretical results emphasized charge carriers as a necessary precondition of electroconvection because free-charges in the fluid can response to the external electric field. Therefore, ionized molecules are considered as responsible for the driving of electroconvective flows. In experiments, finite conductivity is achieved by adding charge-carrying dye molecules or in non-dyed liquid crystals by impurities of the samples. The phenomenon of electroconvection is explained by the Carr-Helfrich theory, supported by numerical simulations. In the present paper, we show that electroconvection may occur also in pure nematic liquid crystals. By means of particle-based numerical simulation we found that bound charges emerge by alignment of polarized liquid crystal molecules in response to the external electric field. In our simulations we could reproduce the characteristic features of electroconvection, such as directorflow patterns, the phase-transition in the voltage-frequency diagram, and dislocation climb/glide motion, which are well known from experiments and hydrodynamic simulations under the assumption of free charge carriers.

},
author = {Lee, Kuang-Wu and Pöschel, Thorsten},
doi = {10.1039/C7SM02055D},
faupublication = {yes},
journal = {Soft Matter},
pages = {8816-8823},
peerreviewed = {unknown},
title = {{Electroconvection} of {Pure} {Nematic} {Liquid} {Crystals} without {Free} {Charge} {Carriers}},
volume = {120},
year = {2017}
}
@article{faucris.109943944,
abstract = {In contrast to a still common belief, a steadily flowing hourglass changes its weight over the course of time (Shen and Scott in Am J Phys 53(8):787-788, 1985). We will show that, nevertheless, it is possible to construct hourglasses that do not change their weight. © 2007 Springer-Verlag.},
author = {Becker, Volker and Pöschel, Thorsten},
doi = {10.1007/s10035-007-0081-z},
faupublication = {no},
journal = {Granular Matter},
keywords = {Granular flow; Hour glass flow},
pages = {231-232},
peerreviewed = {Yes},
title = {{Hourglass} of constant weight},
volume = {10},
year = {2008}
}
@incollection{faucris.218985819,
abstract = {From the classical kinetic theory of gases we know the equation of state of the ideal gas, βp = n (see Chap. 1). For real gases, the interaction forces between the molecules lead to corrections to the ideal gas equation of state. We mention the classical theory by van der Waals and the systematic expansions with respect to density, called virial expansions.},
author = {Ebeling, Werner and Pöschel, Thorsten},
booktitle = {Lectures on Quantum Statistics},
doi = {10.1007/978-3-030-05734-3_5},
faupublication = {yes},
isbn = {978-3-030-05734-3},
note = {CRIS-Team Scopus Importer:2019-05-28},
pages = {141-170},
peerreviewed = {unknown},
publisher = {Springer Verlag},
series = {Lecture Notes in Physics},
title = {{Real} gas quantum statistics},
volume = {953},
year = {2019}
}
@article{faucris.119189004,
abstract = {The flow of granular material in a rotating cylinder was simulated by molecular dynamics in two dimensions using spherical as well as nonspherical grains. At very low but constant angular velocity we found that the flow varies irregularly with time. The particles move in a stick-slip mode, i.e. there are avalanches of different size at the surface of the granular material. Observing the traces of the particles we found that there are unstable convection cells. Our results agree with recent experiments by Rajchenbach and Rolf. © 1995.},
author = {Pöschel, Thorsten and Buchholtz, Volkhard},
doi = {10.1016/0960-0779(94)00193-T},
faupublication = {no},
journal = {Chaos Solitons & Fractals},
peerreviewed = {Yes},
title = {{Complex} flow of granular material in a rotating cylinder},
volume = {5},
year = {1995}
}
@article{faucris.119477644,
abstract = {Unsaturated wet granular media are usually modelled using force laws based on analytical and empirical results of liquid bridge forces between pairs of grains. These models make ad-hoc assumptions on the liquid volume present in the bridges and its distribution. The force between grains and rupture criterion of the bridge are a function of this assumed volume of liquid, in addition to other parameters like contact angle of the liquid, geometry of the grains and the inter grain distance. To study the initial volume and morphology of liquid bridges, hydrodynamic simulation of dynamic effects leading to formation of liquid bridges at grain scale are indispensable. We use a Smoothed Particle Hydrodynamics algorithm to simulate the hydrodynamics of the evolution of the free surface using a novel freesurface-capillary model, inspired by the molecular basis of surface tension. We present validations for the model and simulations of formation and rupture of liquid bridges.},
author = {Nair, Prapanch and Pöschel, Thorsten},
doi = {10.1051/epjconf/201714009005},
faupublication = {yes},
journal = {EPJ Web of Conferences},
peerreviewed = {unknown},
title = {{Structural} changes in wet granular matter due to drainage},
volume = {140},
year = {2017}
}
@article{faucris.120798304,
abstract = {The static and dynamic properties of binary mixtures of hard spheres with a diameter ratio of σ / σ =0.1 and a mass ratio of m / m =0.001 are investigated using event driven molecular dynamics. The contact values of the pair correlation functions are found to compare favorably with recently proposed theoretical expressions. The transport coefficients of the mixture, determined from simulation, are compared to the predictions of the revised Enskog theory using both a third-order Sonine expansion and direct simulation Monte Carlo. Overall, the Enskog theory provides a fairly good description of the simulation data, with the exception of systems at the smallest mole fraction of larger spheres (x =0.01) examined. A "fines effect" was observed at higher packing fractions, where adding smaller spheres to a system of large spheres decreases the viscosity of the mixture; this effect is not captured by the Enskog theory. © 2009 American Institute of Physics.},
author = {Bannerman, Marcus and Lue, Leo},
doi = {10.1063/1.3120488},
faupublication = {no},
journal = {Journal of Chemical Physics},
peerreviewed = {Yes},
title = {{Transport} properties of highly asymmetric hard-sphere mixtures},
volume = {130},
year = {2009}
}
@article{faucris.117264444,
abstract = {We have studied and resolved occupancy correlations in the existing average structure model of the complex metallic alloy xi'-Al-Pd-Mn [Boudard et al., Philos. Mag. A 74, 939 (1996)], which has approximately 320 atoms in the unit cell and many fractionally occupied sites. Model variants were constructed systematically in a tiling-decoration approach and subjected to simulated annealing by use of both density functional theory and molecular dynamics with empirical potentials. To obtain a measure for thermodynamic stability, we reproduce the Al-Pd-Mn phase diagram at T = 0 K, and derive an enthalpy of formation for each structure. Our optimal structure resolves a cloud of fractionally occupied sites in pseudo-Mackay clusters. In particular, we demonstrate the presence of rotational degrees of freedom of an Al-9 inner shell, which is caged within two icosahedrally symmetric outer shells Al-30 and Pd-12. Outside these clusters, the chemical ordering on a chain of three nearby sites surprisingly breaks the inversion symmetry of the surrounding structure, and couples to an Al/vacancy site nearby. Our refined tiling-decoration model applies to any structure within the epsilon-phases family, including the metastable decagonal quasicrystalline phase.},
author = {Engel, Michael and Frigan, Benjamin and Santana, Alejandro and Schopf, Daniel and Trebin, Hans-Rainer and Mihalkovic, Marek},
doi = {10.1103/PhysRevB.84.184203},
faupublication = {no},
journal = {Physical Review B},
peerreviewed = {Yes},
title = {{Low}-temperature structure of xi '-{Al}-{Pd}-{Mn} optimized by ab initio methods},
volume = {84},
year = {2011}
}
@article{faucris.109905884,
abstract = {As the kinetic equations become invalid, the constitutive relations (CRs), necessary for the closure of hydrodynamics, are not derivable from first-principles anymore. An ensemble of monodisperse, nearly elastic hard spheres in such conditions that the standard Navier-Stokes granular hydrodynamics (NSGH) breaks down becuase of large densities, not large inelasticity. This paper aims to check whether a variant of NSGH can still be used in an extreme case whether a variant of NSGH can still be used in an extreme case when the packing fraction is close to the maximum possible value, corresponding to hexagonal packing of spheres.},
author = {Meerson, Baruch and Pöschel, Thorsten and Bromberg, Yaron},
doi = {10.1103/PhysRevLett.91.024301},
faupublication = {no},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Close}-packed floating clusters: {Granular} hydrodynamics beyond the freezing point?},
url = {http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.91.024301},
volume = {91},
year = {2003}
}
@article{faucris.216711694,
abstract = {Orientational ordering is a necessary step in the crystallization of molecules and anisotropic colloids. Plastic crystals, which are possible mesophases between the fluid and fully ordered crystal, are translationally ordered but exhibit no long range orientational order. Here, we study the two-dimensional phase behavior of hard regular polygons with edge number n = 3-12. This family of particles provides a model system to isolate the effect of shape and symmetry on the existence of plastic crystal phases. We show that the symmetry group of the particle, G, and the symmetry group of the local environment in the crystal, H, together determine plastic colloidal crystal phase behavior in two dimensions. If G contains completely the symmetry elements of H, then a plastic crystal phase is absent. If G and H share some but not all nontrivial symmetry elements, then a plastic crystal phase exists with preferred particle orientations that recover the absent symmetry elements of the crystal; we call this phase the discrete plastic crystal phase. If G and H share no nontrivial symmetry elements, then a plastic crystal phase exists without preferred orientations, which we call an indiscrete plastic crystal.},
author = {Shen, Wenbo and Antonaglia, James and Anderson, Joshua A. and Engel, Michael and Van Anders, Greg and Glotzer, Sharon C.},
doi = {10.1039/c9sm00016j},
faupublication = {no},
journal = {Soft Matter},
note = {CRIS-Team WoS Importer:2019-04-30},
pages = {2571-2579},
peerreviewed = {Yes},
title = {{Symmetries} in hard polygon systems determine plastic colloidal crystal mesophases in two dimensions},
volume = {15},
year = {2019}
}
@inproceedings{faucris.119619984,
abstract = {Additive manufacturing constitutes a promising production technology with potential application in a broad range of industrial areas. In this type of manufacturing process, objects are created from powder particles by adding layers of material upon one another through selectively melting particles from the powder bed. However, understanding the mechanical behavior of the powder during manufacturing as a function of material properties and particle shape is an essential pre-requisite for optimizing the production process. Here we develop a numerical tool for modeling the dynamics of powder particles during additive manufacturing based on force-based simulations by means of the Discrete Element Method (DEM). An existing DEM software (LIGGGHTS) is extended in order to study the transport of powder particles of complex geometric shapes through accounting for the boundary conditions inherent to the manufacturing proces},
author = {Ribeiro Parteli, Eric Josef},
booktitle = {AIP Conference Proceedings},
doi = {10.1063/1.4811898},
faupublication = {yes},
isbn = {9780735411661},
keywords = {additive manufacturing; DEM simulation; granular materials; multisphere method},
pages = {185-188},
title = {{DEM} simulation of particles of complex shapes using the multisphere method: {Application} for additive manufacturing},
venue = {Sydney, NSW},
volume = {1542},
year = {2013}
}
@inproceedings{faucris.117367844,
author = {Engel, Michael},
booktitle = {Aperiodic 2009},
date = {2009-09-13/2009-09-18},
faupublication = {no},
peerreviewed = {unknown},
title = {{Spontaneous} formation of a dense aperiodic crystal from hard tetrahedra},
venue = {Liverpool},
year = {2009}
}
@article{faucris.116682764,
abstract = {Sediment transport along the surface drives geophysical phenomena as diverse as wind erosion and dune formation. The main length scale controlling the dynamics of sediment erosion and deposition is the saturation length L , which characterizes the flux response to a change in transport conditions. Here we derive, for the first time, an expression predicting L as a function of the average sediment velocity under different physical environments. Our expression accounts for both the characteristics of sediment entrainment and the saturation of particle and fluid velocities, and has only two physical parameters which can be estimated directly from independent experiments. We show that our expression is consistent with measurements of L in both aeolian and subaqueous transport regimes over at least 5 orders of magnitude in the ratio of fluid and particle density, including on Mars. © 2013 American Physical Society.},
author = {Ribeiro Parteli, Eric Josef and Pähtz, Thomas and Kok, Jasper F. and Herrmann, Hans J.},
doi = {10.1103/PhysRevLett.111.218002},
faupublication = {yes},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Flux} saturation length of sediment transport},
volume = {111},
year = {2013}
}
@inproceedings{faucris.122570184,
author = {Engel, Michael},
booktitle = {Aperiodic 2015},
date = {2015-08-30/2015-09-04},
faupublication = {no},
peerreviewed = {unknown},
title = {{Cabinet} of curiosities: self-assembly of unusual crystal structures},
venue = {Prag},
year = {2015}
}
@article{faucris.122051864,
abstract = {The fluid and solid equations of state for hard parallel squares and cubes are reinvestigated here over a wide range of densities.We use a novel single-speed version of molecular dynamics. Our results are compared with those from earlier simulations, as well as with the predictions of the virial series, the cell model, and Kirkwood's many-body singleoccupancy model. The single-occupancy model is applied to give the absolute entropy of the solid phases just as was done earlier for hard disks and hard spheres. As we should expect, the excellent agreement found here with all relevant previous work shows very clearly that configurational properties, such as the equation of state, do not require the maximumentropy Maxwell-Boltzmann velocity distribution. For both hard squares and hard cubes the free-volume theory provides a good description of the high-density solid-phase pressure. Hard parallel squares appear to exhibit a second-order melting transition at a density of 0.79 relative to close-packing. Hard parallel cubes have a more complicated equation of state, with several relatively-gentle curvature changes, but nothing so abrupt as to indicate a firstorder melting transition. Because the number-dependence for the cubes is relatively large the exact nature of the cube transition remains unknown. © The Author(s) 2009.},
author = {Bannerman, Marcus and Hoover, Wm. G. and Hoover, Carol G.},
doi = {10.1007/s10955-009-9795-0},
faupublication = {yes},
journal = {Journal of Statistical Physics},
keywords = {Computational methods; Melting transition; Molecular dynamics},
pages = {715-732},
peerreviewed = {Yes},
title = {{Single}-speed molecular dynamics of hard parallel squares and cubes},
volume = {136},
year = {2009}
}
@article{faucris.123019644,
abstract = {By means of experiments in microgravity conditions, we show that granular systems subjected to sinusoidal vibrations respond either by harmonic or gaslike dynamics, depending on the parameters of the vibration, amplitude and frequency, and the container size, while subharmonic response is unstable, except for extreme material properties and particular initial conditions. The absence of subharmonic response in vibrated granular systems implies that granular dampeners cannot reveal higher-order resonances, which makes them even more attractive for technical applications. Extensive molecular dynamics simulations support our findings.},
author = {Kollmer, Jonathan and Tupy, Martin and Heckel, Michael and Sack, Achim and Pöschel, Thorsten},
doi = {10.1103/PhysRevApplied.3.024007},
faupublication = {yes},
journal = {Physical Review Applied},
peerreviewed = {Yes},
title = {{Absence} of subharmonic response in vibrated granular systems under microgravity conditions},
volume = {3},
year = {2015}
}
@article{faucris.121335764,
abstract = {Computersimulationen und Experimente mit Schaumblasen zeigen, wie man Kugeln nicht nur dicht stapelt, sondern auch mechanisch stabil.},
author = {Engel, Michael},
faupublication = {no},
journal = {Physik Journal},
pages = {24-25},
peerreviewed = {unknown},
title = {{Brennpunkt}: {Aus} {Schaum} gebaut},
volume = {11},
year = {2012}
}
@phdthesis{faucris.109481944,
abstract = {
English:

Recently a fingering morphology, resembling the hydrodynamic Saffman-Taylor instability, was identified in the quasi-two-dimensional electrodeposition of copper by M. Lòpez-Salvans et al. [Phys. Rev. Lett. 76, 4062 (1996)]. This thesis tries to elucidate the underlying mechanism by measuring the dispersion relation of the growing front.

The instability is accompanied by gravity-driven convection rolls at the electrodes, which are examined using particle image velocimetry. While at the anode the theory presented by Chazalviel et al. [J. Electroanal. Chem. 407, 61 (1996)] describes the convection roll, the flow field at the cathode is more complicated because of the growing deposit. In particular, the analysis of the orientation of the velocity vectors reveals some lag of the development of the convection roll compared to the finger envelope.

In thin-layer electrodeposition the dissipated electrical energy leads to a substantial heating of the ion solution. Measurements of the resulting temperature field by means of an infrared camera indicate, that its properties correspond closely with the development of the concentration field. In particular, we find that the thermal gradients at the electrodes act similar to a weak additional driving force to the convection rolls driven by concentration gradients.

Deutsch:

Die elektrolytische Abscheidung von Metallen in dünnen Zellen führt in Abhängigkeit von den experimentellen Parametern zu einer Vielzahl unterschiedlicher Morphologien. M. Lòpez-Salvans et al. [Phys. Rev. Lett. 76, 4062 (1996)] beobachten erstmals das Wachstum eines Deposits mit einer fingerartigen Hüllkurve. Als Elektrolyt dient eine Kupfersulfatlösung mit einer geringen Beigabe von Natriumsulfat. Unmittelbar vor dem wachsenden Deposit bildet sich eine Kupferhydroxidschicht aus. Die so entstehende Situation weist Ähnlichkeit mit der Saffman-Taylor-Instabilität auf, bei der ebenfalls Finger entstehen. Ziel der vorliegenden Arbeit ist es, durch Messungen, die als Grundlage einer theoretischen Modellierung dienen können, zum Verständnis des Fingerbildungsphänomens beizutragen. Hierzu werden drei verschiedene Fragestellungen untersucht:

(1) Zur Charakterisierung der initialen Phase der Instabilität wird die zeitliche Entwicklung der Fingerhüllkurve vermessen. Die einzelnen Moden des Fourierspektrums der Grenzlinie zeigen ein exponentielles Wachstum. Die Abhängigkeit der Wachstumsraten der Moden von deren Wellenzahl ergibt die Dispersionsrelation. Durch die gezielte Anregung einer kurzwelligen Mode mit Hilfe einer strukturierten Elektrode kann auch eine negative Wachstumsrate genau bestimmt werden. Für den Vergleich mit der Theorie wird die Abhängigkeit der Dispersionsrelation von den experimentellen Parametern Spannung, Zellhöhe und Zellneigung bestimmt.

(2) Die Änderung der Kupferionenkonzentration unmittelbar an den Elektroden geht mit einer Veränderung der Dichte des Elektrolyten einher. Diese führt je nach Elektrode zu einer Auf- oder Abwärtsströmung, die eine mit der Zeit anwachsende Konvektionsrolle antreibt. Das Entstehen dieser Konvektionsrolle lässt sich unterbinden, indem die Zelle in einer vertikalen Konfiguration betrieben wird. Diese unterdrückt jedoch auch die Fingerbildung. Zur Untersuchung des Strömungsfeldes in der Zelle werden dem Elektrolyten Tracerpartikel hinzugefügt und deren Bahnen mit Hilfe des Programmpaketes Artemis verfolgt. Ein Vergleich der an der Anode gemessenen Strömungsgeschwindigkeiten mit der Theorie von Chazalviel et al. [J. Electroanal. Chem. 407, 61 (1996)] zeigt befriedigende Ergebnisse. An der Katode schiebt das wachsende Deposit die Konvektionsrolle vor sich her, so dass deren Ausdehnung gegen einen festen Wert konvergiert.Ein Vergleich der Ausrichtung der Konvektionsrolle mit den Normalenvektoren der Fingerhüllkurve zeigt, dass zu Beginn der Instabilität die Entwicklung der Grenzlinie der des Strömungsfeldes vorauseilt.

(3) Die während eines Experimentes dissipierte elektrische Energie führt aufgrund des geringen Elektrolytvolumens zu einer messbaren Erwärmung. Dies wirft die Frage auf, ob hierbei Temperaturgradienten enstehen und zu Dichtegradienten führen, die die von den Konzentrationsunterschieden getriebenen Konvektionsrollen beeinflussen. Messungen des Temperaturfeldes mit einer Infrarotkamera zeigen, dass der Beitrag der Temperaturgradienten zur gesamten Dichtedifferenz kleiner als 4% bleibt.

},
author = {Schröter, Matthias},
faupublication = {no},
peerreviewed = {automatic},
school = {Friedrich-Alexander-Universität Erlangen-Nürnberg},
title = {{Die} {Fingermorphologie} in der {Elektrodeposition}, ein komplexes {Grenzflächenphänomen}},
year = {2003}
}
@inproceedings{faucris.122039984,
abstract = {Additive Fertigungsprozesse erfahren zurzeit zunehmendes Inte-resse aus Wirtschaft und Forschung, so zum Beispiel durch den Sonderforschungsbereich 814 (SFB 814) an der Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU). Der Arbeitskreis Modellierung innerhalb des SFB 814 widmet sich hierbei dem Auf- und Ausbau von grundlegendem Prozessverständnis mit dem Schwerpunkt auf pulver- und strahlbasierten Fertigungs-prozessen. Dies wird durch Anwendung komplexer Modelle er-reicht, welche die unterschiedlichen physikalischen Skalen und Effekte nachbilden. Der Schlüssel zum tieferen Prozessver-ständnis liegt dabei neben der eigentlichen Modellierung in der Verknüpfung der Einflüsse, die aus Effekten unterschiedlicher Größen- und Zeitskalen stammen. Das Ziel ist dabei stets die Optimierung des resultierenden Bauteils, vor allem hinsichtlich der Qualität der Oberfläche, der mechanischen Eigenschaften und der Wirtschaftlichkeit des Herstellungsprozesses.},
author = {Bauereiß, Andreas and Ribeiro Parteli, Eric Josef and Riedlbauer, Daniel-Rouven and Stingl, Michael},
booktitle = {Industriekolloqium des Sonderforschungsbereichs 814 – Additive Fertigung},
editor = {Dietmar Drummer},
faupublication = {yes},
pages = {117 - 130},
peerreviewed = {unknown},
title = {{Numerische} {Simulation} pulver- und strahlbasierter additiver {Fertigungsprozesse}},
year = {2012}
}
@article{faucris.116700804,
abstract = {Recently, it has been demonstrated [Magee , Phys. Rev. Lett. 96, 207802 (2006)] that isolated square-well homopolymers can spontaneously break chiral symmetry and "freeze" into helical structures at sufficiently low temperatures. This behavior is interesting because the square-well homopolymer is itself achiral. In this work, we use event-driven molecular dynamics combined with an optimized parallel tempering scheme to study this polymer model over a wide range of parameters. We examine the conditions where the helix structure is stable and determine how the interaction parameters of the polymer govern the details of the helix structure. The width of the square well (proportional to lambda) is found to control the radius of the helix, which decreases with increasing well width until the polymer forms a coiled sphere for sufficiently large wells. The helices are found to be stable for only a "window" of molecular weights. If the polymer is too short, the helix will not form. If the polymer is too long, the helix is no longer the minimum energy structure, and other folded structures will form. The size of this window is governed by the chain stiffness, which in this model is a function of the ratio of the monomer size to the bond length. Outside this window, the polymer still freezes into a locked structure at low temperature; however, unless the chain is sufficiently stiff, this structure will not be unique and is similar to a glassy state.},
author = {Bannerman, Marcus and Lue, Leo and Magee, J.E.},
doi = {10.1103/PhysRevE.80.021801},
faupublication = {no},
journal = {Physical Review E},
keywords = {chiral symmetries;molecular dynamics method;polymers},
peerreviewed = {Yes},
title = {{Structure} and stability of helices in square-well homopolymers},
volume = {80},
year = {2009}
}
@article{faucris.109852864,
abstract = {Transverse dunes, which form under unidirectional winds and have fixed profile in the direction perpendicular to the wind, occur on all celestial objects of our solar system where dunes have been detected. Here we perform a numerical study of the average turbulent wind flow over a transverse dune by means of computational fluid dynamics simulations. We find that the length of the zone of recirculating flow at the dune lee-the separation bubble-displays a surprisingly strong dependence on the wind shear velocity, u *: it is nearly independent of u * for shear velocities within the range between 0.2â€...m/s and 0.8â€...m/s but increases linearly with u * for larger shear velocities. Our calculations show that transport in the direction opposite to dune migration within the separation bubble can be sustained if u * is larger than approximately 0.39â€...m/s, whereas a larger value of u * (about 0.49â€...m/s) is required to initiate this reverse transport.},
author = {Araújo, Ascânio D. and Ribeiro Parteli, Eric Josef and Pöschel, Thorsten and Andrade, José S. and Herrmann, Hans J.},
doi = {10.1038/srep02858},
faupublication = {yes},
journal = {Scientific Reports},
peerreviewed = {Yes},
title = {{Numerical} modeling of the wind flow over a transverse dune},
volume = {3},
year = {2013}
}
@article{faucris.122141844,
abstract = {We analyze the velocity distribution function of force-free granular gases in the regime of homogeneous cooling when deviations from the Maxwellian distribution may be accounted only by the leading term in the Sonine polynomial expansion, quantified by the second coefficient a. We go beyond the linear approximation for a and find three different values (three roots) for this coefficient which correspond to a scaling solution of the Boltzmann equation. The stability analysis performed showed, however, that among these three roots only one corresponds to a stable scaling solution. This is very close to a, obtained in previous studies in a linear with respect to a approximation.},
author = {Brilliantov, Nikolai and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.61.2809},
faupublication = {no},
journal = {Physical Review E},
pages = {2809-2812},
peerreviewed = {Yes},
title = {{Deviation} from {Maxwell} distribution in granular gases with constant restitution coefficient},
volume = {61},
year = {2000}
}
@article{faucris.106891444,
abstract = {The investigation of regular and irregular patterns in nonlinear oscillators is an outstanding problem in physics and in all natural sciences. In general, regularity is understood as tantamount to periodicity. However, there is now a flurry of works proving the existence of "antiperiodicity", an unfamiliar type of regularity. Here we report the experimental observation and numerical corroboration of antiperiodic oscillations. In contrast to the isolated solutions presently known, we report infinite hierarchies of antiperiodic waveforms that can be tuned continuously and that form wide spiral-shaped stability phases in the control parameter plane. The waveform complexity increases towards the focal point common to all spirals, a key hub interconnecting them all.},
author = {Freire, J. G. and Cabeza, C. and Marti, A. C. and Pöschel, Thorsten and Gallas, Jason},
doi = {10.1038/srep01958},
faupublication = {yes},
journal = {Scientific Reports},
peerreviewed = {Yes},
title = {{Antiperiodic} oscillations},
volume = {3},
year = {2013}
}
@article{faucris.116711804,
abstract = {We study the distribution of periodic orbits in one-dimensional two-parameter maps. Specifically, we report an exact expression to quantify the growth of the number of periodic orbits for discrete-time dynamical systems governed by polynomial equations of motion of arbitrary degree. In addition, we compute high-resolution phase diagrams for quartic and for both normal forms of cubic dynamics and show that their stability phases emerge all distributed in a similar way, preserving a characteristic invariant ordering. Such coincidences are remarkable since our exact expression shows the total number of orbits of these systems to differ dramatically by more than several millions, even for quite low periods. All this seems to indicate that, surprisingly, the total number and the distribution of stable phases is not significantly affected by the specific nature of the nonlinearity present in the equations of motion.},
author = {Gallas, Jason and Brison, Owen J.},
doi = {10.1016/j.physa.2014.05.049},
faupublication = {yes},
journal = {Physica A-Statistical Mechanics and Its Applications},
pages = {313 - 318},
peerreviewed = {Yes},
title = {{What} is the effective impact of the explosive orbital growth in discrete-time one-dimensional polynomial dynamical systems?},
volume = {410},
year = {2014}
}
@article{faucris.106318564,
abstract = {We present the densest known packing of regular tetrahedra with density phi = 4000/4671 = 0.856341 .... Like the recently discovered packings of Kallus et al. and Torquato-Jiao, our packing is crystalline with a unit cell of four tetrahedra forming two triangular dipyramids (dimer clusters). We show that our packing has maximal density within a three-parameter family of dimer packings. Numerical compressions starting from random configurations suggest that the packing may be optimal at least for small cells with up to 16 tetrahedra and periodic boundaries.},
author = {Engel, Michael and Glotzer, Sharon C. and Chen, Elizabeth R.},
doi = {10.1007/s00454-010-9273-0},
faupublication = {no},
journal = {Discrete & Computational Geometry},
keywords = {Crystallography;Packing;Regular solid;Hilbert problem},
pages = {253-280},
peerreviewed = {Yes},
title = {{Dense} {Crystalline} {Dimer} {Packings} of {Regular} {Tetrahedra}},
volume = {44},
year = {2010}
}
@article{faucris.116719724,
abstract = {Vertical shaking of a mixture of small and large beads can lead to segregation where the large beads either accumulate at the top of the sample, the so-called Brazil nut effect (BNE), or at the bottom, the reverse Brazil nut effect (RBNE). Here we demonstrate experimentally a sharp transition from the RBNE to the BNE when the particle coefficient of friction increases due to aging of the particles. This result can be explained by the two competing mechanisms of buoyancy and sidewall-driven convection, where the latter is assumed to grow in strength with increasing friction.},
author = {Schröter, Matthias and Swinney, Harry L. and Ulrich, Stephan},
doi = {10.1103/PhysRevE.76.042301},
faupublication = {no},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Influence} of friction on granular segregation},
volume = {76},
year = {2007}
}
@article{faucris.119197584,
abstract = {The velocity distribution function of granular gases in the homogeneous cooling state as well as some heated granular gases decays for large velocities as fexp(-const×v). That is, its high-energy tail is overpopulated as compared with the Maxwell distribution. At the present time, there is no theory to describe the influence of the tail on the kinetic characteristics of granular gases. We develop an approach to quantify the overpopulated tail and analyze its impact on granular gas properties, in particular on the cooling coefficient. We observe and explain anomalously slow relaxation of the velocity distribution function to its steady state. © 2006 The American Physical Society.},
author = {Pöschel, Thorsten and Brilliantov, Nikolai V. and Formella, Arno},
doi = {10.1103/PhysRevE.74.041302},
faupublication = {no},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Impact} of high-energy tails on granular gas properties},
volume = {74},
year = {2006}
}
@inproceedings{faucris.122054504,
abstract = {We report a numerical investigation of the structural properties of very large three-dimensional heaps of granular material produced by ballistic deposition from extended circular dropping areas. Very large heaps are found to contain three new geometrical characteristics not observed before: they may have two external angles of repose, an internal angle of repose, and four distinct packing fraction (density) regions. Such characteristics are shown to be directly correlated with the size of the dropping zone. In addition, we also describe how noise during the deposition affects the final heap structur},
author = {Gallas, Jason and Pöschel, Thorsten and Topic, Nikola},
booktitle = {XXIII ICTAM},
date = {2012-08-19/2012-08-24},
faupublication = {yes},
peerreviewed = {unknown},
title = {{Structure} of granular packings},
venue = {Beijing},
year = {2012}
}
@article{faucris.109912924,
abstract = {We investigate the collision of adhesive viscoelastic spheres in quasistatic approximation where the adhesive interaction is described by the Johnson, Kendall, and Roberts (JKR) theory. The collision dynamics, based on the dynamic contact force, describes both restitutive collisions quantified by the coefficient of restitution ε as well as aggregative collisions, characterized by the critical aggregative impact velocity gcr. Both quantities ε and gcr depend sensitively on the impact velocity and particle size. Our results agree well with laboratory experiments. © 2007 The American Physical Society.},
author = {Brilliantov, Nikolai V. and Albers, Nicole and Spahn, Frank and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.76.051302},
faupublication = {no},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Collision} dynamics of granular particles with adhesion},
volume = {76},
year = {2007}
}
@article{faucris.120048324,
abstract = {A numerical study that aims to analyze the thermal mechanisms of unsteady, supersonic granular flow by means of hydrodynamic simulations of the Navier-Stokes granular equation is reported in this paper. For this purpose, a paradigmatic problem in granular dynamics such as the Faraday instability is selected. Two different approaches for the Navier-Stokes transport coefficients for granular materials are considered, namely the traditional Jenkins-Richman theory for moderately dense quasi-elastic grains and the improved Garzó-Dufty-Lutsko theory for arbitrary inelasticity, which we also present here. Both the solutions are compared with event-driven simulations of the same system under the same conditions, by analyzing the density, temperature and velocity field. Important differences are found between the two approaches, leading to interesting implications. In particular, the heat transfer mechanism coupled to the density gradient, which is a distinctive feature of inelastic granular gases, is responsible for a major discrepancy in the temperature field and hence in the diffusion mechanisms. © IOP Publishing and Deutsche Physikalische Gesellschaft.},
author = {Garzó, Vicente and Almazán Torres, Lidia and Carrillo, José A. and Salueña, Clara and Pöschel, Thorsten},
doi = {10.1088/1367-2630/15/4/043044},
faupublication = {yes},
journal = {New Journal of Physics},
peerreviewed = {Yes},
title = {{A} numerical study of the {Navier}-{Stokes} transport coefficients for two-dimensional granular hydrodynamics},
volume = {15},
year = {2013}
}
@article{faucris.122041524,
abstract = {Sand dunes are ubiquitous in deserts, on coasts, on the sea bottom, and on the surface of Mars, Venus and Titan. The quantitative understanding of dune dynamics is thus of relevance for a broad range of physical, geological and planetary sciences. A morphodynamic model for dunes, which combines an analytical description of the average turbulent wind field over the topography with a continuum saltation model, has proven successful to quantitatively reproduce the shape of aeolian dunes of different types. We present a short review on the physics of dune formation and the model development, as well as some future plans for further developments and applications.},
author = {Ribeiro Parteli, Eric Josef and Kroy, Klaus and Tsoar, Haim and Andrade, José S. and Pöschel, Thorsten},
doi = {10.1140/epjst/e2014-02263-2},
faupublication = {yes},
journal = {European Physical Journal: Special Topics},
pages = {2269-2283},
peerreviewed = {Yes},
title = {{Morphodynamic} modeling of aeolian dunes: {Review} and future plans},
volume = {223},
year = {2014}
}
@article{faucris.109987504,
abstract = {We study the mechanism leading to the formation of stripe-like patterns in a rectangular container filled with a sub-monolayer of frictional spherical particles when it is subjected to horizontal oscillations. By means of Molecular Dynamics simulations we could reproduce the experimental results. Systematic simulations allow to identify friction to be responsible for the pattern formation, that is, the tangential interaction between contacting particles and between the particles and the floor of the container. When particles are in contact with the floor and other adjacent particles simultaneously, there emerges a frustrated situation in which the particles are prevented from rolling on the floor. This effect leads to local jamming and eventually to stripe-like pattern formation. In the long time evolution, the stripes are unstable. Stripes may merge as well as disintegrate. © 2013 Springer-Verlag Berlin Heidelberg.},
author = {Krengel, Dominik and Strobl, Severin and Sack, Achim and Heckel, Michael and Pöschel, Thorsten},
doi = {10.1007/s10035-013-0411-2},
faupublication = {yes},
journal = {Granular Matter},
keywords = {Frustration effects; Horizontal shaking; Pattern formation},
pages = {377-387},
peerreviewed = {Yes},
title = {{Pattern} formation in a horizontally shaken granular submonolayer},
volume = {15},
year = {2013}
}
@inproceedings{faucris.109930524,
abstract = {Cohesive powders form agglomerates that can be very porous. Hence they are also very fragile. Consider a process of complete fragmentation on a characteristic length scale I, where the fragments are subsequently allowed to settle under gravity. If this fragmentation-reagglomeration cycle is repeated sufficiently often, the powder develops a fractal substructure with robust statistical properties. The structural evolution is discussed for two different models: The first one is an off-lattice model, in which a fragment does not stick to the surface of other fragments that have already settled, but rolls down until it finds a locally stable position. The second one is a simpler lattice model, in which a fragment sticks at first contact with the agglomerate of fragments that have already settled. Results for the fragment size distribution are shown as well. One can distinguish scale invariant dust and fragments of a characteristic size. Their role in the process of structure formation will be addressed. © 2009 American Institute of Physic},
author = {Wolf, D. E. and Pöschel, Thorsten and Schwager, T. and Weuster, A. and Brendel, L.},
booktitle = {6th International Conference on Micromechanics of Granular Media, Powders and Grains 2009},
doi = {10.1063/1.3180065},
faupublication = {yes},
isbn = {9780735406827},
keywords = {Fractals macroscopic aggregates; Granular systems; Pattern formation; Porous materials; Powders},
pages = {859-862},
title = {{Fractal} substructures due to fragmentation and reagglomeration},
venue = {Golden, CO},
volume = {1145},
year = {2009}
}
@inproceedings{faucris.109847584,
author = {Engel, Michael},
booktitle = {10th International Conference on Quasicrystals},
date = {2009-07-06/2009-07-11},
faupublication = {no},
peerreviewed = {unknown},
title = {{Entropic} stabilization of quasicrystals in the {Lennard}-{Jones}-{Gauss} system},
venue = {Eidgenössische Technische Hochschule Zürich},
year = {2009}
}
@incollection{faucris.218986811,
abstract = {With increasing density of plasmas, non-ideality effects become more and more apparent. This is of particular importance for plasmas with deep bound states, that is, when the thermal energy is smaller than or of the same order as the ground state energies of the atoms in the plasma. For hydrogen this is the case already for T < 10
^{5}
K. Then, except for very low density, the convergence of the expansions becomes worse and we have to consider higher order terms. Sometimes even the transition to other expansion parameters, as the fugacity is recommended.},
author = {Ebeling, Werner and Pöschel, Thorsten},
booktitle = {Lectures on Quantum Statistics},
doi = {10.1007/978-3-030-05734-3_7},
faupublication = {yes},
isbn = {978-3-030-05734-3},
note = {CRIS-Team Scopus Importer:2019-05-28},
pages = {211-231},
peerreviewed = {unknown},
publisher = {Springer Verlag},
series = {Lecture Notes in Physics},
title = {{Non}-ideality and deep bound states in plasmas},
volume = {953},
year = {2019}
}
@article{faucris.122098504,
abstract = {Pressure-controlled displacement of an oil-water interface is studied in dense packings of functionalized glass beads with well-defined spatial wettability correlations. An enhanced dissipation is observed if the typical extension xi of the same-type wetting domains is smaller than the average bead diameter d. Three-dimensional imaging using x-ray microtomography shows that the frequencies n(s) of residual droplet volumes s for different xi collapse onto the same curve. This indicates that the additional dissipation for small xi is due to contact line pinning rather than an increase of capillary break-up and coalescence events.},
author = {Schröter, Matthias and Murison, Julie and Semin, Benoît and Baret, Jean-Christophe and Herminghaus, Stephan and Brinkmann, Martin},
doi = {10.1103/PhysRevApplied.2.034002},
faupublication = {no},
journal = {Physical Review Applied},
peerreviewed = {unknown},
title = {{Wetting} {Heterogeneities} in {Porous} {Media} {Control} {Flow} {Dissipation}},
volume = {2},
year = {2014}
}
@inproceedings{faucris.113993484,
abstract = {Fluidized beds with secondary gas injection enjoy great popularity in process industry. Owing to their characteristic properties such as intense mixing of solids, excellent mass and heat transfer conditions as well as easy handling of solids, this type of apparatus is applied in various fields of process engineering nowadays. In the past decades research concerning fluidized beds with secondary gas injection has focused on understanding how solid particles and the injected gas are distributed within the apparatus. With the aid of invasive measurement techniques the region surrounding the injector nozzle was investigated with respect to the penetration depth of the gas jet above the nozzle orifice as well as the jet opening angle. A major drawback of the previously used measurement techniques consists in their invasive nature. Penetration of the injection zone by a probe can severely influence the local flow pattern and consequently has a detrimental effect on the reliability of the measured data. Therefore in the presented work for the first time the solids distribution as well as the motion of a single particle in a fluidized bed with secondary gas injection has been investigated by positron emission particle tracking (PEPT). This non-invasive technique is based on labeling one single particle, randomly selected from the bulk, radioactively, which allows for tracking its motion with high temporal and spatial resolution. The obtained data are compared with results derived from invasive measurements. Moreover PEPT-data have been used to perform investigations on the residence time behavior of particles within the jet region and the suspended phase. It could be found that the combination of invasive measurements and PEPT provide valuable information for the design and optimization of fluidized bed reactors with a well-defined injection zone.},
author = {Hensler, Timo and Tupy, Martin and Strer, Timo and Pöschel, Thorsten and Wirth, Karl-Ernst},
booktitle = {7th World Congress on Particle Technology, WCPT 2014},
doi = {10.1016/j.proeng.2015.01.204},
faupublication = {yes},
keywords = {Fluidized bed; positron emission particle tracking; residence time behavior; secondary gas injection; solids distribution},
pages = {850-857},
peerreviewed = {Yes},
publisher = {Elsevier Ltd},
title = {{Particle} tracking in fluidized beds with secondary gas injection},
volume = {102},
year = {2015}
}
@article{faucris.114383324,
abstract = {We study complex oscillations generated by the de Pillis-Radunskaya model of cancer growth, a model including interactions between tumor cells, healthy cells, and activated immune system cells. We report a wide-ranging systematic numerical classification of the oscillatory states and of their relative abundance. The dynamical states of the cell populations are characterized here by two independent and complementary types of stability diagrams: Lyapunov and isospike diagrams. The model is found to display stability phases organized regularly in old and new ways: Apart from the familiar spirals of stability, it displays exceptionally long zig-zag networks and intermixed cascades of two- and three-doubling flanked stability islands previously detected only in feedback systems with delay. In addition, we also characterize the interplay between continuous spike-adding and spike-doubling mechanisms responsible for the unbounded complexification of periodic wave patterns. This article is dedicated to Prof. Hans Jürgen Herrmann on the occasion of his 60th birthday.},
author = {Gallas, Jason and Gallas, Michelle R. and Gallas, Marcia R.},
doi = {10.1140/epjst/e2014-02254-3},
faupublication = {yes},
journal = {European Physical Journal: Special Topics},
pages = {2131--2144},
peerreviewed = {unknown},
title = {{Distribution} of chaos and periodic spikes in a three-cell population model of cancer},
volume = {223},
year = {2014}
}
@incollection{faucris.116681664,
address = {New York},
author = {Ribeiro Parteli, Eric Josef},
booktitle = {Encyclopedia of Planetary Landforms},
editor = {Hargitai, H., Kereszturi, Ákos},
faupublication = {yes},
pages = {1 - 2},
peerreviewed = {unknown},
publisher = {Springer},
title = {{Drop} {Dune}},
year = {2014}
}
@article{faucris.119320564,
abstract = {We present the first study of fluid distribution inside porous media imaged by neutron tomography. We demonstrate that this technique has matured sufficiently to deliver pore level results. The major advantage of neutron tomography is the contrast mechanism of using deuterated phases. This allows high contrast imaging without the need to add large amounts of inorganic salts as dopants, required to achieve adequate contrast for X-ray tomography studies. Measurements were performed at the Antares beamline (MLZ, Garching) with a voxel size of 11.8 μm. We propose this technique as a useful tool for studying mutliphase phenomena in porous media where the results are known to depend on the salinty and species of ions present, such as low salinity water, surfactant, and polymer flooding.},
author = {Schröter, Matthias and Murison, Julie and Moosavi, Robabeh and Schulz, Michael and Schillinger, Burkhard},
doi = {10.1021/acs.energyfuels.5b01403},
faupublication = {no},
journal = {Energy & Fuels},
pages = {6271-6276},
peerreviewed = {unknown},
title = {{Neutron} {Tomography} as a {Tool} to {Study} {Immiscible} {Fluids} in {Porous} {Media} without {Chemical} {Dopants}},
volume = {29},
year = {2015}
}
@article{faucris.119740984,
abstract = {Barchan dunes - crescent-shaped dunes that form in areas of unidirectional winds and low sand availability - commonly display an asymmetric shape, with one limb extended downwind. Several factors have been identified as potential causes for barchan dune asymmetry on Earth and Mars: asymmetric bimodal wind regime, topography, influx asymmetry and dune collision. However, the dynamics and potential range of barchan morphologies emerging under each specific scenario that leads to dune asymmetry are far from being understood. In the present work, we use dune modeling in order to investigate the formation and evolution of asymmetric barchans. We find that a bimodal wind regime causes limb extension when the divergence angle between primary and secondary winds is larger than 90°, whereas the extended limb evolves into a seif dune if the ratio between secondary and primary transport rates is larger than 25%. Calculations of dune formation on an inclined surface under constant wind direction also lead to barchan asymmetry, however no seif dune is obtained from surface tilting alone. Asymmetric barchans migrating along a tilted surface move laterally, with transverse migration velocity proportional to the slope of the terrain. Limb elongation induced by topography can occur when a barchan crosses a topographic rise. Furthermore, transient asymmetric barchan shapes with extended limb also emerge during collisions between dunes or due to an asymmetric influx. Our findings can be useful for making quantitative inference on local wind regimes or spatial heterogeneities in transport conditions of planetary dune fields hosting asymmetric barchans. © 2013 Elsevier B.V.},
author = {Ribeiro Parteli, Eric Josef and Durán, Orencio and Bourke, Mary C. and Tsoar, Haim and Pöschel, Thorsten and Herrmann, Hans J.},
doi = {10.1016/j.aeolia.2013.12.002},
faupublication = {yes},
journal = {Aeolian Research},
keywords = {Barchan dunes; Dune asymmetry; Dune model; Sand transport; Wind erosion},
pages = {121-133},
peerreviewed = {Yes},
title = {{Origins} of barchan dune asymmetry: {Insights} from numerical simulations},
volume = {12},
year = {2014}
}
@article{faucris.117264224,
abstract = {We report large-scale computer simulations of the hard-disk system at high densities in the region of the melting transition. Our simulations reproduce the equation of state, previously obtained using the event-chain Monte Carlo algorithm, with a massively parallel implementation of the local Monte Carlo method and with event-driven molecular dynamics. We analyze the relative performance of these simulation methods to sample configuration space and approach equilibrium. Our results confirm the first-order nature of the melting phase transition in hard disks. Phase coexistence is visualized for individual configurations via the orientational order parameter field. The analysis of positional order confirms the existence of the hexatic phase.},
author = {Engel, Michael and Anderson, Joshua A. and Glotzer, Sharon C. and Isobe, Masaharu and Bernard, Etienne P. and Krauth, Werner},
doi = {10.1103/PhysRevE.87.042134},
faupublication = {no},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Hard}-disk equation of state: {First}-order liquid-hexatic transition in two dimensions with three simulation methods},
volume = {87},
year = {2013}
}
@book{faucris.113993044,
abstract = {This chapter contains sections titled: Introduction Forces Between Granular Particles Elastic Forces Viscous Forces Adhesion of Contacting Particles Collision of Granular Particles Coefficient of Restitution Dimensional Analysis Coefficient of Restitution for Spheres Coefficient of Restitution for Adhesive Collisions Conclusion References.},
author = {Pöschel, Thorsten and Brilliantov, Nikolai},
doi = {10.1002/352760362X.ch8},
faupublication = {yes},
isbn = {9783527403738},
keywords = {Collision of adhesive viscoelastic particles; Collision of granular particles; Dense granular flow; Forces between granula particles; Physics of granular media},
pages = {189-209},
peerreviewed = {Yes},
publisher = {wiley},
title = {{Collision} of {Adhesive} {Viscoelastic} {Particles}},
year = {2005}
}
@article{faucris.119404604,
abstract = {The homogenization of granular flows through narrow pipes is important for a broad range of technological and industrial applications. Here we show, by means of molecular dynamics simulations, that such homogenization can be achieved by adding a helical inner-wall texture to the pipe, without the need for energy input from any external source. By using such a texture, jamming is prevented and the granular flux can be predicted using a modified Beverloo equation that accounts for the wavelength of the helical texture.},
author = {Verbücheln, Felix and Ribeiro Parteli, Eric Josef and Pöschel, Thorsten},
doi = {10.1051/epjconf/201714003069},
faupublication = {yes},
journal = {EPJ Web of Conferences},
peerreviewed = {unknown},
title = {{Homogenization} of granular pipe flow by means of helical inner-wall texture},
volume = {140},
year = {2017}
}
@article{faucris.109463904,
abstract = {We investigate the residual distribution of structural defects in very tall packings of disks deposited randomly in large channels. By performing simulations involving the sedimentation of up to 50 × 10 9 particles we find all deposits to consistently show a non-zero residual density of defects obeying a characteristic power-law as a function of the channel width. This remarkable finding corrects the widespread belief that the density of defects should vanish algebraically with growing height. A non-zero residual density of defects implies a type of long-range spatial order in the packing, as opposed to only local ordering. In addition, we find deposits of particles to involve considerably less randomness than generally presumed.},
author = {Topic, Nikola and Pöschel, Thorsten and Gallas, Jason},
doi = {10.1038/srep12703},
faupublication = {yes},
journal = {Scientific Reports},
peerreviewed = {Yes},
title = {{Residual} {Defect} {Density} in {Random} {Disks} {Deposits}},
volume = {5},
year = {2015}
}
@inproceedings{faucris.123095764,
author = {Engel, Michael},
booktitle = {Workshop on Crystals and Random Networks},
date = {2015-02-09/2015-02-13},
faupublication = {no},
peerreviewed = {unknown},
title = {{Packing} and crystallization of hard shapes: from disks to tetrahedra},
venue = {Institute for Computational and Experimental Research in Mathematics, Brown University, Providence, RI},
year = {2015}
}
@article{faucris.109929204,
abstract = {Given an equidistribution for probabilities p(i) -1/N, i = 1,...,N. What is the expected corresponding rank ordered frequency distribution f(i), i=1,...,N, if an ensemble of M events is drawn? © 2002 The American Physical Society.},
author = {Pöschel, Thorsten and Freund, Jan A.},
doi = {10.1103/PhysRevE.66.026103},
faupublication = {no},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Finite}-sample frequency distributions originating from an equiprobability distribution},
url = {http://journals.aps.org/pre/abstract/10.1103/PhysRevE.66.026103},
volume = {66},
year = {2002}
}
@article{faucris.114387504,
abstract = {We discuss several models for granular particles commonly used in Molecular Dynamics simulations of granular materials, including spheres with linear dashpot force, viscoelastic spheres and adhesive viscoelastic spheres. Starting from the vectorial interaction forces we derive the coefficients of normal and tangential restitution as functions of the vectorial impact velocity and of the material constants. We review the methods of measurements of the coefficients of restitution and characterize the coefficient of normal restitution as a fluctuating quantity. Moreover, the scaling behavior and the influence of different force laws on the dynamical system behavior are discussed. The powerful method of event-driven Molecular Dynamics is described and the algorithmic simulation technique is explained in detail. Finally we discuss the limitations of event-driven MD.},
author = {Pöschel, Thorsten and Brilliantov, Nikolai and Formella, Arno and Heckel, Michael and Kruelle, Christof and Müller, Patric and Salueña, Clara and Schwager, Thomas},
doi = {10.3166/ejece.12.827-870},
faupublication = {yes},
journal = {European Journal of Environmental and Civil Engineering},
pages = {827--870},
peerreviewed = {Yes},
title = {{Contact} of granular particles and the simulation of rapid flows using event-driven molecular dynamics},
volume = {12},
year = {2008}
}
@article{faucris.119298564,
abstract = {Sound propagation in water-saturated granular sediments is known to depend on the sediment porosity, but few data in the literature address both the frequency and porosity dependency. To begin to address this deficiency, a fluidized bed technique was used to control the porosity of an artificial sediment composed of glass spheres of 265 mu m diameter. Time-of-flight measurements and the Fourier phase technique were utilized to determine the sound speed for frequencies from 300 to 800 kHz and porosities from 0.37 to 0.43. A Biot-based model qualitatively describes the porosity dependence. (C) 2011 Acoustical Society America},
author = {Schröter, Matthias and Argo IV, Theodore F. and Guild, Matthew D. and Wilson, Preston S. and Radin, Charles and Swinney, Harry L.},
doi = {10.1121/1.3544678},
faupublication = {no},
journal = {Journal of the Acoustical Society of America},
pages = {EL101-EL107},
peerreviewed = {Yes},
title = {{Sound} speed in water-saturated glass beads as a function of frequency and porosity},
volume = {129},
year = {2011}
}
@inproceedings{faucris.109849784,
author = {Engel, Michael},
booktitle = {Quasiperiodic Tilings and Related Topics},
date = {2009-06-19/2009-06-22},
faupublication = {no},
peerreviewed = {unknown},
title = {{Observation} of one-component quasicrystals in simulations},
venue = {Kochi University},
year = {2009}
}
@article{faucris.119184384,
abstract = {We experimentally investigate the energy dissipation rate in sinusoidally driven boxes which are partly filled by granular material under conditions of weightlessness. We identify two different modes of granular dynamics, depending on the amplitude of driving, A. For intense forcing, A>A, the material is found in the collect-and-collide regime where the center of mass of the granulate moves synchronously with the driven container, while for weak forcing, A},
author = {Sack, Achim and Heckel, Michael and Kollmer, Jonathan and Zimber, Fabian and Pöschel, Thorsten},
doi = {10.1103/PhysRevLett.111.018001},
faupublication = {yes},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Energy} dissipation in driven granular matter in the absence of gravity},
volume = {111},
year = {2013}
}
@article{faucris.109811064,
abstract = {We revisit the problem of the structure of a nano-powder subjected to repeated fragmentation and sedimentation, and extend the analysis to the more relevant three-dimensional (3D) case. One important question not addressed previously is how the fractal dimension and dust exponent depend on space dimension. We find that the qualitative behavior of the nano-powder in three dimensions is similar to that in two dimensions. But the fractal dimension changes from 1.6 ± 0.1 in two dimensions to 2.1 ± 0.1 in three dimensions. The scaling relation between the fractal dimension and the dust exponent characterizing the fragment size distribution is the same as in two dimensions. The universality of these exponents is addressed by comparing the results with a much simpler lattice model. Although the different settling kinetics of the fragments leads to different anisotropies, the fractal properties are not affected.},
author = {Topic, Nikola and Weuster, Arnulf and Pöschel, Thorsten and Wolf, Dieter},
doi = {10.1088/1367-2630/17/1/013024},
faupublication = {yes},
journal = {New Journal of Physics},
keywords = {fractals; granular systems; macroscopic aggregates; pourous materials; powders},
peerreviewed = {Yes},
title = {{Structure} of a three-dimensional nano-powder subjected to repeated fragmentation and sedimentation},
volume = {17},
year = {2015}
}
@article{faucris.213926450,
abstract = {The intensity of a monochromatic X-ray beam decreases exponentially with the distance it has traveled inside a material; this behavior is commonly referred to as Beer-Lambert's law. Knowledge of the material-specific attenuation coefficient mu allows us to determine the thickness of a sample from the intensity decrease the beam has experienced. However, classical X-ray tubes emit a polychromatic bremsstrahlung-spectrum. And the attenuation coefficients of all materials depend on the photon energy: photons with high energy are attenuated less than photons with low energy. In consequence, the X-ray spectrum changes while traveling through the medium; due to the relative increase in high energy photons, this effect is called beam hardening. For this varying spectrum, the Beer-Lambert law only remains valid if mu is replaced by an effective attenuation coefficient mu(eff) which depends not only on the material but also on its thickness x and the details of the X-ray setup used. We present here a way to deduce mu(eff)(x) from a small number of auxiliary measurements using a phenomenological model. This model can then be used to determine an unknown material thickness or in the case of a granular media its volume fraction. Published under license by AIP Publishing.},
author = {Baur, Manuel and Uhlmann, Norman and Pöschel, Thorsten and Schröter, Matthias},
doi = {10.1063/1.5080540},
faupublication = {yes},
journal = {Review of Scientific Instruments},
note = {CRIS-Team WoS Importer:2019-03-20},
peerreviewed = {Yes},
title = {{Correction} of beam hardening in {X}-ray radiograms},
volume = {90},
year = {2019}
}
@article{faucris.122074304,
abstract = {Following the recent development of a stable event-detection algorithm for hard-sphere systems, the implications of more complex interaction models are examined. The relative location of particles leads to ambiguity when it is used to determine the interaction state of a particle in stepped potentials, such as the square-well model. To correctly predict the next event in these systems, the concept of an additional state that is tracked separately from the particle position is introduced and integrated into the stable algorithm for event detection.},
author = {Strobl, Severin and Bannerman, Marcus and Pöschel, Thorsten},
doi = {10.1007/s40571-016-0106-7},
faupublication = {yes},
journal = {Computational Particle Mechanics},
keywords = {DEM; Event-driven; Molecular dynamics; Square well; Stepped potential; Collision detection;},
pages = {383–388},
peerreviewed = {Yes},
title = {{Stable} algorithm for event detection in event-driven particle dynamics: logical states},
volume = {3},
year = {2016}
}
@article{faucris.116715104,
abstract = {A statistical description of static granular material requires ergodic sampling of the phase space spanned by the different configurations of the particles. We periodically fluidize a column of glass beads and find that the sequence of volume fractions phi of postfluidized states is history independent and Gaussian distributed about a stationary state. The standard deviation of phi exhibits, as a function of phi, a minimum corresponding to a maximum in the number of statistically independent regions. Measurements of the fluctuations enable us to determine the compactivity X, a temperaturelike state variable introduced in the statistical theory of Edwards and Oakeshott [Physica A 157, 1080 (1989)].},
author = {Schröter, Matthias and Swinney, Harry L. and Goldman, Daniel I.},
doi = {10.1103/PhysRevE.71.030301},
faupublication = {no},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Stationary} state volume fluctuations in a granular medium},
volume = {71},
year = {2005}
}
@article{faucris.117275004,
abstract = {The dynamics of quasicrystals is characterized by the existence of phason excitations in addition to the usual phonon modes. In order to investigate their interplay on an elementary level we resort to various one-dimensional model systems. The main observables are the static, the incoherent, and the coherent structure factor, which are extracted from molecular dynamics simulations. For the validation of the algorithms, results for the harmonic periodic chain are presented. We then study the Fibonacci chain with harmonic and anharmonic interaction potentials. In the dynamic Fibonacci chain neighboring atoms interact by double-well potentials allowing for phason flips. The difference between the structure factors of the dynamic and the harmonic Fibonacci chain lies in the temperature dependence of the phonon line width. If a bias is introduced in the well depth, dispersionless optic phonon bands split off.},
author = {Engel, Michael and Sonntag, Steffen and Lipp, Hansjörg and Trebin, Hans-Rainer},
doi = {10.1103/PhysRevB.75.144203},
faupublication = {no},
journal = {Physical Review B},
peerreviewed = {Yes},
title = {{Structure} factors of harmonic and anharmonic {Fibonacci} chains by molecular dynamics simulations},
volume = {75},
year = {2007}
}
@article{faucris.106996164,
abstract = {Stochastic rotation dynamics (SRD) is a widely used method for the

mesoscopic modeling of complex fluids, such as colloidal suspensions or

multiphase flows. In this method, however, the underlying Cartesian grid

defining the coarse-grained interaction volumes induces anisotropy. We

propose an isotropic, lattice-free variant of stochastic rotation

dynamics, termed iSRD. Instead of Cartesian grid cells, we employ

randomly distributed spherical interaction volumes. This eliminates the

requirement of a grid shift, which is essential in standard SRD to

maintain Galilean invariance. We derive analytical expressions for the

viscosity and the diffusion coefficient in relation to the model

parameters, which show excellent agreement with the results obtained in

iSRD simulations. The proposed algorithm is particularly suitable to

model systems bound by walls of complex shape, where the domain cannot

be meshed uniformly. The presented approach is not limited to SRD but is

applicable to any other mesoscopic method, where particles interact

within certain coarse-grained volumes.},
author = {Mühlbauer, Sebastian and Strobl, Severin and Pöschel, Thorsten},
doi = {10.1103/PhysRevFluids.2.124204},
faupublication = {yes},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Isotropic} stochastic rotation dynamics},
volume = {2},
year = {2017}
}
@article{faucris.217790523,
abstract = {Pt catalysts are widely studied for the oxygen reduction reaction, but their cost and susceptibility to poisoning limit their use. A strategy to address both problems is to incorporate a second transition metal to form a bimetallic alloy; however, the durability of such catalysts can be hampered by leaching of non-noble metal components. Here, we show that random alloyed surfaces can be stabilized to achieve high durability by depositing the alloyed phase on top of intermetallic seeds using a model system with PdCu cores and PtCu shells. Specifically, random alloyed PtCu shells were deposited on PdCu seeds that were either the atomically random face-centered cubic phase (FCC A1, Fm3m) or the atomically ordered CsCl-like phase (B2, Pm3m). Precise control over crystallite size, particle shape, and composition allowed for comparison of these two core@shell PdCu@PtCu catalysts and the effects of the core phase on electrocatalytic durability. Indeed, the nanocatalyst with the intermetallic core saw only an 18% decrease in activity after stability testing (and minimal Cu leaching), whereas the nanocatalyst with the random alloy core saw a 58% decrease (and greater Cu leaching). The origin of this enhanced durability was probed by classical molecular dynamics simulations of model catalysts, with good agreement between model and experiment. Although many random alloy and intermetallic nanocatalysts have been evaluated, this study directly compares random alloy and intermetallic cores for electrocatalysis with the enhanced durability achieved with the intermetallic cores likely general to other core@shell nanocatalysts.},
author = {Gamler, Jocelyn T.L. and Leonardi, Alberto and Ashberry, Hannah M. and Daanen, Nicholas N. and Losovyj, Yaroslav and Unocic, Raymond R. and Engel, Michael and Skrabalak, Sara E.},
doi = {10.1021/acsnano.8b08007},
faupublication = {yes},
journal = {ACS nano},
keywords = {electrocatalysts; multimetallic; nanocatalysts; nanoparticles; platinum alloys},
note = {CRIS-Team Scopus Importer:2019-05-17},
pages = {4008-4017},
peerreviewed = {Yes},
title = {{Achieving} {Highly} {Durable} {Random} {Alloy} {Nanocatalysts} through {Intermetallic} {Cores}},
volume = {13},
year = {2019}
}
@article{faucris.109964404,
abstract = {We investigate autogenous fragmentation of dry granular material in rotating cylinders using two-dimensional molecular dynamics. By evaluation of spatial force distributions achieved numerically for various rotation velocities we argue that comminution occurs mainly due to the existence of these force chains. A statistical analysis of these force chains explains the spatial distribution of comminution efficiency in ball mills as measured experimentally by ROTHKEGEL and ROLF.},
author = {Buchholtz, V. and Freund, Jan A. and Pöschel, Thorsten},
doi = {10.1007/PL00011052},
faupublication = {no},
journal = {Bulk Solids Handling},
pages = {159-171},
peerreviewed = {Yes},
title = {{Molecular} dynamics of comminution in ball mills},
volume = {20},
year = {2000}
}
@article{faucris.124012944,
abstract = {The screen is a key part of stereoscopic display systems using polarization to separate the different channels for each eye. The system crosstalk, characterizing the imperfection of the screen in terms of preserving the polarization of the incoming signal, and the scattering rate, characterizing the ability of the screen to deliver the incoming light to the viewers, determine the image quality of the system. Both values will depend on the viewing angle. In this work we measure the performance of three silver screens and three rear-projection screens. Additionally, we measure the surface texture of the screens using white-light interferometry. While part of our optical results can be explained by the surface roughness, more work is needed to understand the optical properties of the screens from a microscopic model.[Figure not available: see fulltext.] © 2012 3D Display Research Center and Springer-Verlag Berlin Heidelberg.},
author = {Schröter, Matthias and Fischer, Cornelius and Zhang, Xiaozhu and Hantke, Kristian},
doi = {10.1007/3DRes.04(2012)4},
faupublication = {no},
journal = {3D Research},
keywords = {ghosting; polarization; screen; stereoscopic projection; surface texture; system crosstalk},
pages = {1-5},
peerreviewed = {unknown},
title = {{Performance} of polarization-based stereoscopy screens},
volume = {3},
year = {2012}
}
@inproceedings{faucris.115441304,
author = {Engel, Michael},
booktitle = {Workshop: Jam-Packed},
date = {2014-09-15/2014-09-18},
faupublication = {no},
peerreviewed = {unknown},
title = {{When} and how can densest packings be achieved with nanoparticles?},
venue = {Erlangen},
year = {2014}
}
@article{faucris.114381784,
abstract = {We report numerical evidence of a new type of wide-ranging organization of mixed-mode oscillations (MMOs) in a model of the peroxidase−oxidase reaction, in the control parameter plane defined by the supply of the reactant NADH and the pH of the medium. In classic MMOs, the intervals of distinct periodic oscillations are always separated from each other by windows of chaos. In contrast, in the new unfolding, such windows of chaos do not exist. Chaos-mediated and nonchaos-mediated MMO phases are separated by a continuous transition boundary in the control parameter plane. In addition, for low pH values, we find an exceptionally wide and intricate mosaic of MMO phases that is described by a detailed phase diagram.},
author = {Gallas, Jason and Hauser, Marcus J.B.},
doi = {10.1021/jz5022069},
faupublication = {yes},
journal = {Journal of Physical Chemistry Letters},
pages = {4187--4193},
peerreviewed = {Yes},
title = {{Nonchaos}-{Mediated} {Mixed}-{Mode} {Oscillations} in an {Enzyme} {Reaction} {System}},
volume = {5},
year = {2014}
}
@article{faucris.109937124,
abstract = {We present a universal description of the velocity distribution function of granular gases, f(v), valid for both, small and intermediate velocities where v is close to the thermal velocity and also for large v where the distribution function reveals an exponentially decaying tail. By means of large-scale Monte Carlo simulations and by kinetic theory we show that the deviation from the Maxwell distribution in the high-energy tail leads to small but detectable variation of the cooling coefficient and to extraordinary large relaxation time. © World Scientific Publishing Company.},
author = {Pöschel, Thorsten and Brilliantov, Nikolai V. and Formella, Arno},
doi = {10.1142/S0129183107010966},
faupublication = {no},
journal = {International Journal of Modern Physics C},
keywords = {Granular gases; Overpopulated high-energy tail; Velocity distribution function},
pages = {701-711},
peerreviewed = {Yes},
title = {{Granular} gas cooling and relaxation to the steady state in regard to the overpopulated tail of the velocity distribution},
volume = {18},
year = {2007}
}
@article{faucris.122097184,
abstract = {We present a new mode of transport of spherical particles in a horizontally vibrated channel with sawtooth-shaped side walls. The underlying driving mechanism is based on an interplay of directional energy injection transformed by the sidewall collisions and density-dependent interparticle collisions. Experiments and matching numerics show that the average particle velocity reaches a maximum at 60% of the maximal filling density. Introducing a spatial phase shift between the channel boundaries increases the transport velocity by an order of magnitude. © 2013 American Physical Society.},
author = {Schröter, Matthias and Mobarakabadi, Shahin and Oskoee, Ehsan Nedaaee and Habibi, Mehdi},
doi = {10.1103/PhysRevE.88.042201},
faupublication = {no},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Granular} transport in a horizontally vibrated sawtooth channel},
volume = {88},
year = {2013}
}
@article{faucris.110028204,
abstract = {Experiments and numerical simulations of granular material under swirling motion of the container are presented. At low packing densities the material rotates in the same direction as the swirling motion of the container (rotation). At higher densities the cluster of granular material rotates in the opposite direction (reptation). The change of the direction of the motion of the cluster takes place at a critical packing density while the diffusion coefficient changes significantly. The measured critical density of the packing is in good agreement with results obtained by molecular-dynamics simulation.},
author = {Scherer, Michael A. and Buchholtz, Volkhard and Pöschel, Thorsten and Rehberg, Ingo},
doi = {10.1103/PhysRevE.54.R4560},
faupublication = {no},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Swirling} granular matter: {From} rotation to reptation},
volume = {54},
year = {1996}
}
@article{faucris.114386184,
abstract = {We study the deterministic spin dynamics of an anisotropic magnetic particle in the presence of a magnetic field with a constant longitudinal and a time-dependent transverse component using the Landau-Lifshitz-Gilbert equation. We characterize the dynamical behavior of the system through calculation of the Lyapunov exponents, Poincaré sections, bifurcation diagrams, and Fourier power spectra. In particular we explore the positivity of the largest Lyapunov exponent as a function of the magnitude and frequency of the applied magnetic field and its direction with respect to the main anisotropy axis of the magnetic particle. We find that the system presents multiple transitions between regular and chaotic behaviors. We show that the dynamical phases display a very complicated structure of intricately intermingled chaotic and regular phases.},
author = {Gallas, Jason and Bragard, Jean and Suarez, Omar J. and Laroze, David and Pleiner, H. and Vargaz, P.},
doi = {10.1103/PhysRevE.84.037202},
faupublication = {yes},
journal = {Physical Review E},
pages = {037202},
peerreviewed = {Yes},
title = {{Chaotic} dynamics of a magnetic nanoparticle},
volume = {84},
year = {2011}
}
@article{faucris.122047244,
abstract = {The spontaneous formation of heterogeneous patterns is a hallmark of many nonlinear systems, from biological tissue to evolutionary population dynamics. The standard model for pattern formation in general, and for Turing patterns in chemical reaction-diffusion systems in particular, are deterministic nonlinear partial differential equations where an unstable homogeneous solution gives way to a stable heterogeneous pattern. However, these models fail to fully explain the experimental observation of turbulent patterns with spatio-temporal disorder in chemical systems. Here we introduce a pattern-fluid model as a general concept where turbulence is interpreted as a weakly interacting ensemble obtained by random superposition of stationary solutions to the underlying reaction-diffusion system. The transition from turbulent to stationary patterns is then interpreted as a condensation phenomenon, where the nonlinearity forces one single mode to dominate the ensemble. This model leads to better reproduction of the experimental concentration profiles for the "stationary phases" and reproduces the turbulent chemical patterns observed by Q. Ouyang and H. L. Swinney [Chaos 1, 411 (1991)].},
author = {Scholz, Christian and Schröder-Turk, Gerd and Mecke, Klaus},
doi = {10.1103/PhysRevE.91.042907},
faupublication = {yes},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Pattern}-fluid interpretation of chemical turbulence},
volume = {91},
year = {2015}
}
@inproceedings{faucris.106421524,
author = {Engel, Michael},
booktitle = {Mini Stat Mech Meeting},
date = {2014-01-10/2014-01-12},
faupublication = {no},
peerreviewed = {unknown},
title = {{Beyond} close packing: complex order with simple models},
venue = {Berkeley, California},
year = {2014}
}
@article{faucris.117769124,
abstract = {
By means of particle-based numerical simulations using the discrete element method, we address the

question of how the performance of granular dampers is affected by the shape of the granular particles.

In consistence with previous experiments performed with nearly spherical particles we

fi

nd that

independently of the particles

’

shape, the granular system is characterized by a gas-like regime for

small amplitudes of the container

’

s oscillation and by a collect-and-collide regime for large amplitude

forcing. Both regimes are separated by an optimal operation mode

—

the critical amplitude of the

damping oscillation for which the energy dissipation is maximal

—

which is independent of the particle

shape for given conditions of particle mass, material properties and number of particles. However, in

the gas-like regime, we

fi

nd that spherical particles lead to more ef

fi

cient energy dissipation compared

to complex shaped particles of the same mass. In this regime, a dependence on the damper

’

sef

fi

ciency

on the particle shape is found.

},
author = {Pourtavakoli, Hamzeh and Ribeiro Parteli, Eric Josef and Pöschel, Thorsten},
doi = {10.1088/1367-2630/18/7#/073049},
faupublication = {yes},
journal = {New Journal of Physics},
keywords = {granular matter, numerical simulations, discrete element method, granular dampers},
peerreviewed = {Yes},
title = {{Granular} dampers: does particle shape matter?},
volume = {18},
year = {2016}
}
@article{faucris.116700584,
abstract = {Some dynamical properties for a bouncing ball model are studied. We show that when dissipation is introduced the structure of the phase space is changed and attractors appear. Increasing the amount of dissipation, the edges of the basins of attraction of an attracting fixed point touch the chaotic attractor. Consequently the chaotic attractor and its basin of attraction are destroyed given place to a transient described by a power law with exponent -2. The parameter-space is also studied and we show that it presents a rich structure with infinite self-similar structures of shrimp-shape. (c) 2013 Elsevier B.V. All rights reserved.},
author = {Fregolente Mendes de Oliveira, Diego and Leonel, Edson D.},
doi = {10.1016/j.physa.2012.12.021},
faupublication = {yes},
journal = {Physica A-Statistical Mechanics and Its Applications},
keywords = {Chaos;Fermi-map;Boundary crisis},
pages = {1762-1769},
peerreviewed = {Yes},
title = {{Some} dynamical properties of a classical dissipative bouncing ball model with two nonlinearities},
volume = {392},
year = {2013}
}
@article{faucris.123486264,
abstract = {We propose a new scheme for the two-way coupling of incompressible fluids and deformable bodies, where we focus on a medical application; in particular, secondary bone healing. Our method allows for accurate simulation and visualisation of the secondary bone healing process, which is used to optimise clinical treatment of bone fractures. In our simulation, the soft tissues are simulated as elastic materials using Strain Based Dynamics (SBD), and fluid is simulated using Incompressible Smoothed Particle Hydrodynamics (ISPH). The interaction model we propose works with any type of deformation technique as long as the object surface is represented by a polygonal mesh and the fluid by Lagrangian particles.},
author = {Aburumman, Nadine and Müller, Patric and Nair, Prapanch and Pöschel, Thorsten},
faupublication = {yes},
journal = {Eurographics technical report series},
peerreviewed = {No},
title = {{Coupled} {Simulation} of {Deformable} {Bodies} and {ISPH} {Fluids} for {Secondary} {Bone} {Healing}},
year = {2017}
}
@article{faucris.109901704,
abstract = {Granular ratchets are well-known devices that when driven vertically produce a counterintuitive horizontal transport of particles. Here we report the experimental observation of a complementary effect: the striking ability of circular ratchets to convert their vertical vibration into their own rotation. The average revolution speed shows a maximum value for an optimal tooth height. With no special effort the rotation speed could be maintained steady during several hours. Unexpected random arrests and reversals of the velocity were also observed abundantly. © 2012 American Physical Society.},
author = {Heckel, Michael and Müller, Patric and Pöschel, Thorsten and Gallas, Jason},
doi = {10.1103/PhysRevE.86.061310},
faupublication = {yes},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Circular} ratchets as transducers of vertical vibrations into rotations},
volume = {86},
year = {2012}
}
@article{faucris.116698384,
author = {Behringer, Robert and Jenkins, James and Miloh, Touvia and Orszag, Steven and Pöschel, Thorsten and Rosenau, Philip and Savage, Stuart and Schuss, Zeev and Shemer, Lev},
faupublication = {yes},
journal = {Journal of Fluid Mechanics},
pages = {1 - 2},
peerreviewed = {Yes},
title = {{Obituary}: {PROFESSOR} {ISAAC} {GOLDHIRSCH} 11 {October} 1949–29 {April} 2010},
volume = {655},
year = {2010}
}
@article{faucris.109831744,
abstract = {We investigate the coefficient of normal restitution as a function of the impact velocity, ε(v), for inelastic spheres. We observe oscillating behavior of ε(v) which is superimposed to the known decay of the coefficient of restitution as a function of impact velocity. This remarkable effect was so far unnoticed because under normal circumstances it is screened by statistical scatter. We detected its clear signature by recording large amounts of data using an automated experiment. The new effect may be understood as an interplay between translational and vibrational degrees of freedom of the colliders. Both characteristics of the oscillation, the wavelength and the amplitude, agree quantitatively with a theoretical description of the experiment. © 2013 American Physical Society.},
author = {Müller, Patric and Heckel, Michael and Sack, Achim and Pöschel, Thorsten},
doi = {10.1103/PhysRevLett.110.254301},
faupublication = {yes},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Complex} velocity dependence of the coefficient of restitution of a bouncing ball},
volume = {110},
year = {2013}
}
@article{faucris.124192684,
abstract = {We study the kinetics of prion fibril growth, described by the nucleated polymerization model analytically and by means of numerical experiments. The elementary processes of prion fibril formation lead us to a set of differential equations for the number of fibrils, their total mass, and the number of prion monomers. In difference to previous studies we analyze this set by explicitly taking into account the time-dependence of the prion monomer concentration. The theoretical results agree with experimental data, whereas the generally accepted hypothesis of constant monomer concentration leads to a fibril growth behavior which is not in agreement with experiments. The obtained size distribution of the prion fibril aggregates is shifted significantly toward shorter lengths as compared to earlier results, which leads to a enhanced infectivity of the prion material. Finally, we study the effect of filtering of the inoculated material on the incubation time of the disease.},
author = {Pöschel, Thorsten and Brilliantov, Nikolai and Frömmel, Cornelius},
doi = {10.1016/S0006-3495(03)74767-5},
faupublication = {no},
journal = {Biophysical Journal},
pages = {3460-3474},
peerreviewed = {Yes},
title = {{Kinetics} of {Prion} {Growth}},
url = {http://www.sciencedirect.com/science/article/pii/S0006349503747675},
volume = {85},
year = {2003}
}
@article{faucris.106400624,
abstract = {
As an environment for rich pattern formation, the electroconvection (EC) of nematic liquid crystals (LCs) is studied via fully nonlinear simulations for the first time. Previously, EC was mostly studied by experiments or

by linear/weakly nonlinear hydrodynamic theory for its instability criteria. While the negative dielectric LCs are used in most EC analytical and experimental investigations, EC with positive dielectric LCs is limited to

experiments only, due to their more complex nonlinear behavior. In this work we take a step beyond the existing weakly nonlinear EC research by using a fully nonlinear particle-based simulation. To investigate

the distinct dynamics of positive and negative dielectric LCs, we modified the molecular potential in the LC stochastic rotational model (LC SRD) [Lee et al., J. Chem. Phys., 2015, 142, 164110] to incorporate the

dielectric characteristics and the field-particle interaction. As a result, different convection patterns known in the EC experiments were observed in our simulations, for which those patterns appeared orderly, as a function of external field strength. The simulated director and flow fields correspond to each other well, as found in our experiments. For the positive dielectric LC, we discovered a net directional flow accompanying the travelling EC rolls. This numerical model and its hydrodynamic analysis could be used for precise flow control at the micro-scale, such as nematic colloidal transportation in microfluidics.

},
author = {Lee, Kuang-Wu and Pöschel, Thorsten},
doi = {10.1039/C7RA06757G},
faupublication = {yes},
journal = {RSC Advances},
peerreviewed = {unknown},
title = {{Field}-driven pattern formation in nematic liquid crystals: mesoscopic simulations of electroconvection},
volume = {7},
year = {2017}
}
@article{faucris.122087504,
abstract = {Past work has shown that ions can pass through a membrane more readily in one direction than the other. We demonstrate here in a model and an experiment that for a mixture of small and large particles such asymmetric diffusion can arise solely from an asymmetry in the geometry of the pores of the membrane. Our deterministic simulation considers a two-dimensional gas of elastic disks of two sizes diffusing through a membrane, and our laboratory experiment examines the diffusion of glass beads of two sizes through a metal membrane. In both experiment and simulation, the membrane is permeable only to the smaller particles, and the asymmetric pores lead to an asymmetry in the diffusion rates of these particles. The presence of even a small percentage of large particles can clog a membrane, preventing passage of the small particles in one direction while permitting free flow of the small particles in the other direction. The purely geometric kinetic constraints may play a role in common biological contexts such as membrane ion channels. © 2007 by The National Academy of Sciences of the USA.},
author = {Schröter, Matthias and Shaw, Robert S. and Packard, Norman and Swinney, Harry L.},
doi = {10.1073/pnas.0703280104},
faupublication = {no},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
keywords = {Asymmetric pores; Channels},
pages = {9580-9584},
peerreviewed = {Yes},
title = {{Geometry}-induced asymmetric diffusion},
volume = {104},
year = {2007}
}
@article{faucris.109802924,
abstract = {A recent study claimed that heavy use of equations impedes communication among biologists, as measured by the ability to attract citations from peers. It was suggested that to increase the probability of being cited one should reduce the density of equations in papers, that equations should be moved to appendices, and that math training among biologists should be improved. Here, we report a detailed study of the citation habits among physicists, a community that has traditionally strong training and dependence on mathematical formulations. Is it possible to correlate statistical citation patterns and fear of mathematics in a community whose work strongly depends on equations? By performing a systematic analysis of the citation counts of papers published in one of the leading journals in physics covering all its disciplines, we find striking similarities with distribution of citations recorded in biological sciences. However, based on the standard deviations in citation data of both communities, biologists and physicists, we argue that trends in statistical indicators are not reliable to unambiguously blame mathematics for the existence or lack of citations. We digress briefly about other statistical trends that apparently would also enhance citation success.},
author = {Kollmer, Jonathan and Pöschel, Thorsten and Gallas, Jason},
doi = {10.1088/1367-2630/17/1/013036},
faupublication = {yes},
journal = {New Journal of Physics},
keywords = {citation strategies; science communication; social physics},
peerreviewed = {Yes},
title = {{Are} physicists afraid of mathematics?},
volume = {17},
year = {2015}
}
@article{faucris.122572604,
abstract = {Mixtures of anisotropic nanocrystals promise a great diversity of superlattices and phase behaviors beyond those of single-component systems. However, obtaining a colloidal shape alloy in which two different shapes are thermodynamically coassembled into a crystalline superlattice has remained a challenge. Here we present a joint experimental computational investigation of two geometrically ubiquitous nanocrystalline building blocks-nanorods and nanospheres-that overcome their natural entropic tendency toward macroscopic phase separation and coassemble into three intriguing pluses over centimeter scales, including an AB(2)-type binary superlattice. Monte Carlo simulations reveal that, although this shape alloy is entropically stable at high packing fraction, demixing is favored at experimental densities. Simulations with short-ranged attractive interactions demonstrate that the alloy is stabilized by interactions induced by ligand stabilizers and/or depletion effects. An asymmetry in the relative interaction strength between rods and spheres improves the robustness of the self-assembly process.},
author = {Engel, Michael and Ye, Xingchen and Millan, Jaime A. and Chen, Jun and Diroll, Benjamin T. and Glotzer, Sharon C. and Murray, Christopher B.},
doi = {10.1021/nl403149u},
faupublication = {no},
journal = {Nano Letters},
keywords = {Nanoparticles;Monte Carlo simulation;binary nanocrystal superlattice;electron microscopy;lamellar phase;demixing},
pages = {4980-4988},
peerreviewed = {Yes},
title = {{Shape} {Alloys} of {Nanorods} and {Nanospheres} from {Self}-{Assembly}},
volume = {13},
year = {2013}
}
@article{faucris.223555902,
abstract = {Mutations in the Des gene coding for the muscle-specific intermediate filament protein desmin lead to myopathies and cardiomyopathies. We previously generated a R349P desmin knock-in mouse strain as a patient-mimicking model for the corresponding most frequent human desmin mutation R350P. Since nothing is known about the age-dependent changes in the biomechanics of affected muscles, we investigated the passive and active biomechanics of small fiber bundles from young (17–23 wks), adult (25–45 wks) and aged (>60 wks) heterozygous and homozygous R349P desmin knock-in mice in comparison to wild-type littermates. We used a novel automated biomechatronics platform, the MyoRobot, to perform coherent quantitative recordings of passive (resting length-tension curves, visco-elasticity) and active (caffeine-induced force transients, pCa-force, ‘slack-tests’) parameters to determine age-dependent effects of the R349P desmin mutation in slow-twitch soleus and fast-twitch extensor digitorum longus small fiber bundles. We demonstrate that active force properties are not affected by this mutation while passive steady-state elasticity is vastly altered in R349P desmin fiber bundles compatible with a pre-aged phenotype exhibiting stiffer muscle preparations. Visco-elasticity on the other hand, was not altered. Our study represents the first systematic age-related characterization of small muscle fiber bundle preparation biomechanics in conjunction with inherited desminopathy.},
author = {Haug, Michael and Meyer, Charlotte and Reischl, Barbara and Prölß, Gerhard and Vetter, Karoline and Iberl, Julian and Nübler, Stefanie and Schürmann, Sebastian and Rupitsch, Stefan and Heckel, Michael and Pöschel, Thorsten and Winter, Lilli and Herrmann, Harald and Clemen, Christoph S. and Schröder, Rolf and Friedrich, Oliver},
doi = {10.1038/s41598-019-46723-6},
faupublication = {yes},
journal = {Scientific Reports},
note = {CRIS-Team Scopus Importer:2019-08-02},
peerreviewed = {Yes},
title = {{The} {MyoRobot} technology discloses a premature biomechanical decay of skeletal muscle fiber bundles derived from {R349P} desminopathy mice},
volume = {9},
year = {2019}
}
@article{faucris.116725444,
abstract = {We explore experimentally the fluidization of vertically agitated polymethylmethacrylate spheres wetted by liquid He4. By controlling the temperature around the λ point, we change the properties of the wetting liquid from a normal fluid (helium I) to a superfluid (helium II). For wetting by helium I, the critical acceleration for fluidization (Γc) shows a steep increase close to the saturation of the vapor pressure in the sample cell. For helium II wetting, Γc starts to increase at about 75% saturation, indicating that capillary bridges are enhanced by the superflow of the unsaturated helium film. Above saturation, Γc enters a plateau regime where the capillary force between particles is independent of the bridge volume. The plateau value is found to vary with temperature and shows a peak at 2.1 K, which we attribute to the influence of the specific heat of liquid helium. © 2009 The American Physical Society.},
author = {Schröter, Matthias and Herminghaus, Stephan and Huang, Kai and Sohaili, Masoud},
doi = {10.1103/PhysRevE.79.010301},
faupublication = {no},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Fluidization} of granular media wetted by liquid {He4}},
volume = {79},
year = {2009}
}
@article{faucris.115439764,
abstract = {We study the Rulkov model phase plane, a two-dimensional map-based model that describes

the behavior of a neuron. Keeping constant one of the three parameters, we obtain

phase planes showing well-defined periodicities. We show the importance of the parameter

identifying the periodicities and the number of spikes per burst, quantities that are related

between them by a linear relationship. The zones in which these periodicities are well-defined

exhibit in some cases, shapes similar to those appearing in some palm-tree patterns observed

both in trunks and in leaves. The detailed determination and description of these periodicity

zones could be the basis for a further study on synchronization of nonidentical neurons in

regions in which the domain of the parameter values ensure the fact to work with the same

periodicity. We also analyze the reliability and the limitations of this method.},
author = {RAM´IREZ ´A VILA, G.M. and Gallas, Marcia and Gallas, Jason},
faupublication = {yes},
journal = {Revista Boliviana de Física},
keywords = {Nonlinear dynamics and chaos, bifurcation theory, numerical simulations of chaotic systems, neuroscience, oscillations and resonance.},
peerreviewed = {Yes},
title = {{ANA}´ {LISIS} {DEL} {PLANO} {DE} {FASES} {DE} {UN} {MODELO} {DISCRETO} {DE} {NEURONA} {BASADO} {EN} {LA} {DETERMINACIO}´ {N} {DE} {PERIODICIDADES} {PHASE} {PLANE} {ANALYSIS} {OF} {A} {NEURON} {MAP}-{BASED} {MODEL} {BY} {DETERMINING} {PERIODICITIES}},
volume = {27},
year = {2015}
}
@article{faucris.122026784,
abstract = {A hydrodynamic description of dilute binary gas mixtures comprising smooth inelastic spheres interacting by binary collisions with a random coefficient of restitution is presented. Constitutive relations are derived using the Chapman-Enskog perturbative method, associated with a computer-aided method to allow high-order Sonine polynomial expansions. The transport coefficients obtained are checked against DSMC simulations. The resulting equations are applied to the analysis of a vertically vibrated system. It is shown that differences in the shape of the distributions of the coefficient of restitution are sufficient to produce partial segregation.},
author = {Pöschel, Thorsten and Serero, Dan and Gunkelmann, Nina},
doi = {10.1017/jfm.2015.501},
faupublication = {yes},
journal = {Journal of Fluid Mechanics},
keywords = {granular media; granular mixing; kinetic theory},
pages = {595-621},
peerreviewed = {unknown},
title = {{Hydrodynamics} of binary mixtures of granular gases with stochastic coefficient of restitution},
volume = {781},
year = {2015}
}
@article{faucris.109957584,
abstract = {The gravity-driven flow of granular material through a rough, narrow vertical pipe is described using the Langevin equation formalism. Above a critical particle density the homogeneous flow becomes unstable with respect to short-wave length perturbations. In correspondence with experimental observations, we find clogging and density waves in the flowing material.},
author = {Riethmüller, Tino and Schimansky-Geier, Lutz and Rosenkranz, Dirk and Pöschel, Thorsten},
doi = {10.1007/BF02180213},
faupublication = {no},
journal = {Journal of Statistical Physics},
keywords = {Flow of solids; Granular material; Stochastic processes},
pages = {421-430},
peerreviewed = {Yes},
title = {{Langevin} equation approach to granular flow in a narrow pipe},
volume = {86},
year = {1997}
}
@article{faucris.122566444,
abstract = {The interplay between phase separation and kinetic arrest is important in supramolecular self-assembly, but their effects on emergent orientational order are not well understood when anisotropic building blocks are used. Contrary to the typical progression from disorder to order in isotropic systems, here we report that colloidal oblate discoids initially self-assemble into short, metastable strands with orientational order-regardless of the final structure. The model discoids are suspended in a refractive index and density-matched solvent. Then, we use confocal microscopy experiments and Monte Carlo simulations spanning a broad range of volume fractions and attraction strengths to show that disordered clusters form near coexistence boundaries, whereas oriented strands persist with strong attractions. We rationalize this unusual observation in light of the interaction anisotropy imparted by the discoids. These findings may guide self-assembly for anisotropic systems in which orientational order is desired, such as when tailored mechanical properties are sought.},
author = {Engel, Michael and Hsiao, Lilian C. and Schultz, Benjamin A. and Glaser, Jens and Szakasits, Megan E. and Glotzer, Sharon C. and Solomon, Michael J.},
doi = {10.1038/ncomms9507},
faupublication = {no},
journal = {Nature Communications},
peerreviewed = {Yes},
title = {{Metastable} orientational order of colloidal discoids},
volume = {6},
year = {2015}
}
@masterthesis{faucris.110938124,
author = {Heckel, Michael and et al.},
author_hint = {heckel, m},
faupublication = {no},
peerreviewed = {automatic},
school = {Friedrich-Alexander-Universität Erlangen-Nürnberg},
support_note = {Author relations incomplete. You may find additional data in field 'author_hint'},
title = {{Dynamisches} {Verhalten} granularer {Materie} im {Schwingförderer}, {Diplomarbeit}},
year = {2007}
}
@article{faucris.122886984,
abstract = {The approximants xi, xi' and xi'(n) n of the Al-Mn-Pd quasi-crystal display interesting plastic properties, such as, for example, phason-induced deformation processes and metadislocations. Here we demonstrate that the phases and their deformed or defect states can be described by a simple projection formalism in three-dimensional space-not, as usual, in four to six dimensions. Using this method we can interpret the microstructures observed with electron microscopy as phasonic phase boundaries. Furthermore, we determine the metadislocations of lowest energy and relate them uniquely to experimentally observed ones. Since moving metadislocations in the xi' phase can create new phason planes, we suggest a dislocation-induced phase transition from xi' to xi'(n). The methods developed in this paper can also be applied for various other complex metallic alloys.},
author = {Engel, Michael and Trebin, Hans-Rainer},
doi = {10.1080/14786430500070669},
faupublication = {no},
journal = {Philosophical Magazine},
pages = {2227-2247},
peerreviewed = {Yes},
title = {{A} unified projection formalism for the {Al}-{Pd}-{Mn} quasi-crystal {Xi}-approximants and their metadislocations},
volume = {85},
year = {2005}
}
@article{faucris.119643744,
abstract = {Dense granular clusters often behave like macro-particles. We address this interesting phenomenon in a model system of inelastically colliding hard disks inside a circular box, driven by a thermal wall at zero gravity. Molecular dynamics simulations show a close-packed cluster of almost circular shape, weakly fluctuating in space and isolated from the driving wall by a low-density gas. The density profile of the system agrees very well with the azimuthally symmetric solution of granular hydrostatic equations employing constitutive relations by Grossman et al., whereas the widely used Enskog-type constitutive relations show poor accuracy. We find that fluctuations of the center of mass of the system are Gaussian. This suggests an effective Langevin description in terms of a macro-particle, confined by a harmonic potential and driven by delta-correlated noise. Surprisingly, the fluctuations persist when increasing the number of particles in the system. © 2007 Springer-Verlag.},
author = {Meerson, Baruch and Díez-Minguito, Manuel and Schwager, Thomas and Pöschel, Thorsten},
doi = {10.1007/s10035-007-0055-1},
faupublication = {no},
journal = {Granular Matter},
keywords = {Granular cluster; Granular hydrodynamics; Strong fluctuations},
pages = {21-27},
peerreviewed = {Yes},
title = {{Close}-packed granular clusters: {Hydrostatics} and persistent {Gaussian} fluctuations},
volume = {10},
year = {2007}
}
@article{faucris.119196924,
abstract = {Our study examines the long-time behaviour of a force-free granular gas of viscoelastic particles, for which the coefficient of restitution depends on the impact velocity, as it follows from the solution of the impact problem for viscoelastic spheres. Starting from the Boltzmann equation, we derived the hydrodynamic equations and obtained microscopic expressions for the transport coefficients in terms of the elastic and dissipative parameters of the particle material. We performed the stability analysis of the linearized set of equations and found that any inhomogeneities and vortices vanish after a long time and the system approaches the flow-free stage of homogeneous density. This behaviour is in contrast to that of a gas consisting of particles which interact via a (non-realistic) constant coefficient of restitution, for which inhomogeneities (clusters) and vortex patterns have been proven to arise and to continuously develop.},
author = {Brilliantov, Nikolai and Pöschel, Thorsten},
doi = {10.1098/rsta.2001.0940},
faupublication = {no},
journal = {Philosophical Transactions of the Royal Society A-Mathematical Physical and Engineering Sciences},
keywords = {Clustering; Dissipative gases; Granular gases; Hydrodynamics; Inelastic collisions; Structure formation},
pages = {415-428},
peerreviewed = {Yes},
title = {{Hydrodynamics} of granular gases of viscoelastic particles},
volume = {360},
year = {2002}
}
@inproceedings{faucris.119712824,
abstract = {The rolling motion of a rigid cylinder on an inclined flat viscous surface is investigated and the nonlinear resistance force against rolling, F (v), is derived. For small velocities F (v) increases with velocity due to increasing deformation rate of the surface material. For larger velocity it decreases with velocity due to decreasing contact area between the rolling cylinder and the deformed surface. The cylinder is, moreover, subjected to a viscous drag force and stochastic fluctuations due to a surrounding medium (air). For this system, in a wide range of parameters we observe bistability of the rolling motion. Depending on the material parameters, increasing the noise level may lead to increasing or decreasing average velocity. © 2005 Taylor & Francis Group.},
author = {Pöschel, Thorsten and Schwager, Thomas and Brilliantov, Nikolai V. and Zaikin, A.},
booktitle = {5th International Conference on the Micromechanics of Granular Media: Powders and Grains 2005},
faupublication = {no},
isbn = {9780415383479},
pages = {1247-1251},
title = {{Rolling} friction and bistability of rolling motion},
url = {https://www.scopus.com/inward/record.url?partnerID=HzOxMe3b&scp=84857525008&origin=inward},
venue = {Stuttgart},
volume = {2},
year = {2005}
}
@article{faucris.108761004,
abstract = {
The melting transition of two-dimensional systems is a fundamental problem in condensed matter and statistical physics that has advanced significantly through the application of computational resources and algorithms. Two-dimensional systems present the opportunity for novel phases and phase transition scenarios not observed in 3D systems, but these phases depend sensitively on the system and, thus, predicting how any given 2D system will behave remains a challenge. Here, we report a comprehensive simulation study of the phase behavior near the melting transition of all hard regular polygons with 3≤n≤14 vertices using massively parallel Monte Carlo simulations of up to 1×106 particles. By investigating this family of shapes, we show that the melting transition depends upon both particle shape and symmetry considerations, which together can predict which of three different melting scenarios will occur for a given n. We show that systems of polygons with as few as seven edges behave like hard disks; they melt continuously from a solid to a hexatic fluid and then undergo a first-order transition from the hexatic phase to the isotropic fluid phase. We show that this behavior, which holds for all 7≤n≤14, arises from weak entropic forces among the particles. Strong directional entropic forces align polygons with fewer than seven edges and impose local order in the fluid. These forces can enhance or suppress the discontinuous character of the transition depending on whether the local order in the fluid is compatible with the local order in the solid. As a result, systems of triangles, squares, and hexagons exhibit a Kosterlitz-Thouless-Halperin-Nelson-Young (KTHNY) predicted continuous transition between isotropic fluid and triatic, tetratic, and hexatic phases, respectively, and a continuous transition from the appropriate x-atic to the solid. In particular, we find that systems of hexagons display continuous two-step KTHNY melting. In contrast, due to symmetry incompatibility between the ordered fluid and solid, systems of pentagons and plane-filling fourfold pentilles display a one-step first-order melting of the solid to the isotropic fluid with no intermediate phase.

},
author = {Anderson, Joshua A. and Antonaglia, James and Millan, Jaime A. and Engel, Michael and Glotzer, Sharon C.},
doi = {10.1103/PhysRevX.7.021001},
faupublication = {yes},
journal = {Physical Review X},
peerreviewed = {Yes},
title = {{Shape} and {Symmetry} {Determine} {Two}-{Dimensional} {Melting} {Transitions} of {Hard} {Regular} {Polygons}},
volume = {7},
year = {2017}
}
@article{faucris.215873720,
abstract = {Colloids are rarely perfectly uniform but follow a distribution of sizes, shapes, and charges. This dispersity can be inherent (static) or develop and change over time (dynamic). Despite a long history of research, the conditions under which nonuniform particles crystallize and which crystal forms is still not well understood. Here, we demonstrate that hard spheres with Gaussian radius distribution and dispersity up to 19% always crystallize if compressed slowly enough, and they do so in surprisingly complex ways. This result is obtained by accelerating event-driven simulations with particle swap moves for static dispersity and particle resize moves for dynamic dispersity. Above 6% dispersity, AB(2) Laves, AB(13), and a region of Frank-Kasper phases are found. The Frank-Kasper region includes a quasicrystal approximant with Pearson symbol oS276. Our findings are relevant for ordering phenomena in soft matter and alloys.},
author = {Bommineni, Praveen Kumar and Varela-Rosales, Nydia Roxana and Klement, Marco and Engel, Michael},
doi = {10.1103/PhysRevLett.122.128005},
faupublication = {yes},
journal = {Physical Review Letters},
note = {CRIS-Team WoS Importer:2019-04-12},
peerreviewed = {Yes},
title = {{Complex} {Crystals} from {Size}-{Disperse} {Spheres}},
volume = {122},
year = {2019}
}
@article{faucris.116725884,
abstract = {We measure shear response in packings of glass beads by pulling a thin, rough, metal plate vertically through a bed of volume fraction , which is set, before the plate is pulled, in the range from 0.575 to 0.628. The yield stress is velocity independent over 4 decades and increases exponentially with , with a transition at ≈0.595. An analysis of the measured force fluctuations indicates that the shear modulus is significantly smaller than the bulk modulus. © 2011 Europhysics Letters Association.},
author = {Schröter, Matthias and Métayer, Jean-François and Suntrup III, Donald J. and Radin, Charles and Swinney, Harry L.},
doi = {10.1209/0295-5075/93/64003},
faupublication = {no},
journal = {EPL - Europhysics Letters},
peerreviewed = {Yes},
title = {{Shearing} of frictional sphere packings},
volume = {93},
year = {2011}
}
@inproceedings{faucris.106410964,
abstract = {
Part of the optimization steps for the additive manufacturing is related to the correct understanding of the mechanical behavior of the powder used in the process. Numerical simulations through the Discrete Element Method (DEM) provide a useful means to investigate additive manufacturing process thus assisting and complementing experimental investigations. In particular, with the help of DEM simulations, it is possible to study particle-scale processes that are difficult to access experimentally. We investigate the characteristics of the powder bed deposited onto the manufactured part using a roller as the coating system. Furthermore, the non-spherical shape of real particles is also taken explicitly into account in the numerical simulations. A combination of translational velocity and sinusoidal vibration is used in the roller. The effect of varying the translational velocity, vibration frequency and amplitude in the density and roughness of the formed bed is investigated.

},
address = {Ljubljana},
author = {Schiochet Nasato, Daniel and Pöschel, Thorsten and Ribeiro Parteli, Eric Josef},
booktitle = {6th International Conference on Additive Technologies iCAT},
date = {2016-11-29/2016-11-30},
editor = {Drstvenšek I, Drummer D, Schmidt M},
faupublication = {yes},
isbn = {978-961-285-537-6},
peerreviewed = {unknown},
publisher = {Interesansa - zavod},
title = {{Effect} of vibrations applied to the transport roller in the quality of the powder bed during additive manufacturing},
venue = {Nürnberg},
year = {2016}
}
@article{faucris.212767732,
abstract = {Recent work has introduced social dynamic models of people's stress-related processes, some including amelioration of stress symptoms by support from others. The effects of support may be ``direct'', depending only on the level of support, or ``buffering'', depending on the product of the level of support and level of stress. We focus here on the nonlinear buffering term and use a model involving three variables (and 12 control parameters), including stress as perceived by the individual, physical and psychological symptoms, and currently active social support. This model is quantified by a set of three nonlinear differential equations governing its stationary-state stability, temporal evolution (sometimes oscillatory), and how each variable affects the others. Chaos may appear with periodic forcing of an environmental stress parameter. Here we explore this model carefully as the strength and amplitude of this forcing, and an important psychological parameter relating to self-kindling in the stress response, are varied. Three significant observations are made: 1. There exist many complex but orderly regions of periodicity and chaos, 2. there are nested regions of increasing number of peaks per cycle that may cascade to chaos, and 3. there are areas where more than one state, e.g., a period-2 oscillation and chaos, coexist for the same parameters; which one is reached depends on initial conditions.},
author = {Field, Richard J. and Gallas, Jason and Schuldberg, David},
doi = {10.1016/j.cnsns.2017.01.032},
faupublication = {yes},
journal = {Communications in Nonlinear Science and Numerical Simulation},
note = {EAM Import::2019-03-08},
pages = {135-144},
peerreviewed = {Yes},
title = {{Periodic} and chaotic psychological stress variations as predicted by a social support buffered response model},
volume = {49},
year = {2017}
}
@article{faucris.119273704,
abstract = {The transport of sediment by a fluid along the surface is responsible for dune formation, dust entrainment, and a rich diversity of patterns on the bottom of oceans, rivers, and planetary surfaces. Most previous models of sediment transport have focused on the equilibrium (or saturated) particle flux. However, the morphodynamics of sediment landscapes emerging due to surface transport of sediment is controlled by situations out of equilibrium. In particular, it is controlled by the saturation length characterizing the distance it takes for the particle flux to reach a new equilibrium after a change in flow conditions. The saturation of mass density of particles entrained into transport and the relaxation of particle and fluid velocities constitute the main relevant relaxation mechanisms leading to saturation of the sediment flux. Here we present a theoretical model for sediment transport which, for the first time, accounts for both these relaxation mechanisms and for the different types of sediment entrainment prevailing under different environmental conditions. Our analytical treatment allows us to derive a closed expression for the saturation length of sediment flux, which is general and thus can be applied under different physical conditions.},
author = {Ribeiro Parteli, Eric Josef and Herrmann, Hans J. and Kok, Jasper F. and Päthz, Thomas},
doi = {10.1103/PhysRevE.89.052213},
faupublication = {yes},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Analytical} model for flux saturation in sediment transport},
volume = {89},
year = {2014}
}
@article{faucris.116714664,
abstract = {Recently a fingering morphology, resembling the hydrodynamic Saffman-Taylor instability, was identified in the quasi-two-dimensional electrodeposition of copper. We present here measurements of the dispersion relation of the growing front. The instability is accompanied by gravity-driven convection rolls at the electrodes, which are examined using particle image velocimetry. While at the anode the theory presented by Chazalviel et al. [J. Electroanal. Chem. 407, 61 (1996)] describes the convection roll, the flow field at the cathode is more complicated because of the growing deposit. In particular, the analysis of the orientation of the velocity vectors reveals some lag of the development of the convection roll compared to the finger envelope. © 2002 The American Physical Society.},
author = {Schröter, Matthias and Rehberg, Ingo and Kassner, Klaus and Claret, Josep and Sagués, Francesc},
doi = {10.1103/PhysRevE.65.041607},
faupublication = {no},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Experimental} investigation of the initial regime in fingering electrodeposition: {Dispersion} relation and velocity measurements},
volume = {65},
year = {2002}
}
@inproceedings{faucris.123991604,
abstract = {It has recently been established that sand is mobile under the current Martian cli-mate, including at the North Pole [1,2]. Here we present a detailed study of the morphometry and migration of barchan and dome dunes in the North Polar Region of Mars.},
author = {Ribeiro Parteli, Eric Josef and Bourke, Mary C. and Byrne, S. and Berman, D.},
booktitle = {Third International Planetary Dunes Workshop},
faupublication = {yes},
peerreviewed = {unknown},
title = {{Dune} migration in the north polar region of {Mars}},
year = {2012}
}
@article{faucris.113990404,
abstract = {We present an efficient event-driven algorithm for sequential ballistic deposition of complex-shaped rigid particles. Each of the particles is constructed from hard spheres (typically 5.1000) of variable radii. The sizes and relative positions of the spheres may mutually overlap and can be chosen such that the surface of the resulting particle appears relatively smooth. In the sequential deposition process, by performing steps of rolling and linear motion, the particles move along the steepest descent in a landscape formed by the boundaries and previously deposited particles. The computer time for the simulation of a deposition process depends on the total number of spheres but only weakly on the sizes and shapes of the particles. The proposed algorithm generalizes the Visscher-Bolsterli algorithm [1] which is frequently used for packing of spheres, to non-spherical particles. The proposed event-driven algorithm allows simulations of multi-million particle systems using desktop computers.},
author = {Topic, Nikola and Pöschel, Thorsten},
doi = {10.1016/j.jcp.2015.12.052},
faupublication = {yes},
journal = {Journal of Computational Physics},
keywords = {Complex shaped particles; Event-driven algorithm; Non-spherical particles; Steepest descent ballistic deposition},
pages = {421-437},
peerreviewed = {Yes},
title = {{Steepest} descent ballistic deposition of complex shaped particles},
volume = {308},
year = {2016}
}
@inproceedings{faucris.119278764,
abstract = {We present three heuristics including the usage of domain specific knowledge to improve a general purpose algorithm for the 3D approximate point set match problem and its application to the task of finding 3D motifs (like surface patterns or binding sites) in proteins. The domain specific knowledge and further heuristics are used, under certain conditions, to reduce the run time for the search and to adapt the number of reported matches to the expectations of the user. Compared to the general purpose algorithm, the new version is twice as fast, and can be further improved especially for small tolerances in the matches by means of analyzing the distance distributions of the atoms.},
author = {Formella, Arno and Pöschel, Thorsten and Sanchez Chao, Castor},
booktitle = {14th Portuguese Conference on Artificial Intelligence},
date = {2009-10-12/2009-10-15},
faupublication = {yes},
pages = {101 - 112},
peerreviewed = {unknown},
title = {{Approximate} {3D} motif search in proteins with domain specific knowledge. {New} {Trends} in {Artificial} {Intelligence}},
venue = {Aveiro},
year = {2009}
}
@article{faucris.106912564,
abstract = {Large-scale computer simulations are presented to investigate the avalanche statistics of sandpiles using molecular dynamics. We show that different methods of measurement lead to contradictory conclusions, presumably due to avalanches not reaching the end of the experimental table.},
author = {Buchholtz, Volkhard and Pöschel, Thorsten},
doi = {10.1007/BF02174136},
faupublication = {no},
journal = {Journal of Statistical Physics},
keywords = {Granular material; Self-organized criticality},
pages = {1373-1378},
peerreviewed = {Yes},
title = {{Avalanche} statistics of sand heaps},
volume = {84},
year = {1996}
}
@article{faucris.120054484,
abstract = {We investigate the motion of a hard cylinder rolling down a soft inclined plane. The cylinder is subjected to a viscous drag force and stochastic fluctuations due to the surrounding medium. In a wide range of parameters we observe bistability of the rolling velocity. In dependence on the parameters, increasing noise level may lead to increasing or decreasing average velocity of the cylinder. The approximative analytical theory agrees with numerical results.},
author = {Pöschel, Thorsten and Brilliantov, Nikolai V. and Zaikin, A.},
doi = {10.1209/epl/i2004-10350-y},
faupublication = {no},
journal = {EPL - Europhysics Letters},
pages = {371-377},
peerreviewed = {Yes},
title = {{Bistability} and noise-enhanced velocity of rolling motion},
volume = {69},
year = {2005}
}
@article{faucris.123382644,
abstract = {We study the packing of fine glass powders of mean particle diameter in the range (4-52)μm both experimentally and by numerical DEM simulations. We obtain quantitative agreement between the experimental and numerical results, if both types of attractive forces of particle interaction, adhesion and non-bonded van der Waals forces are taken into account. Our results suggest that considering only viscoelastic and adhesive forces in DEM simulations may lead to incorrect numerical predictions of the behavior of fine powders. Based on the results from simulations and experiments, we propose a mathematical expression to estimate the packing fraction of fine polydisperse powders as a function of the average particle size.},
author = {Ribeiro Parteli, Eric Josef and Schmidt, Jochen and Blümel, Christina and Wirth, Karl-Ernst and Peukert, Wolfgang and Pöschel, Thorsten},
doi = {10.1038/srep06227},
faupublication = {yes},
journal = {Scientific Reports},
peerreviewed = {Yes},
title = {{Attractive} particle interaction forces and packing density of fine glass powders},
volume = {4},
year = {2014}
}
@article{faucris.116728304,
abstract = {The theoretical description of granular materials, or assemblies of macroscopic particles, is a formidable task. Not only are granular materials out of thermal equilibrium, but they are also characterized by dissipative interactions and by static friction. Following a suggestion by S. F. Edwards, researchers have investigated the possible existence of a statistical mechanics of static granular systems, which would permit the description of macroscopic properties of mechanically stable granular assemblies from just a few parameters. The formulation and the validity of such an approach is still a matter of debate. This "emerging area'' focuses on three important questions concerning such a statistical mechanics approach. First, we consider how the phase space of interest is affected by the requirement of mechanical stability. Second, we explore how the intensive parameters analogous to temperature can be determined from experimental or numerical data. Finally, we contrast different ways to express the granular counterpart to the classical Hamiltonian, known as the volume function.},
author = {Schröter, Matthias and Ciamarra, Massimo Pica and Richard, Patrick and Tighe, Brian P.},
doi = {10.1039/c2sm06898b},
faupublication = {no},
journal = {Soft Matter},
month = {Jan},
pages = {9731-9737},
peerreviewed = {Yes},
title = {{Statistical} mechanics for static granular media: open questions},
volume = {8},
year = {2012}
}
@article{faucris.122968604,
abstract = {Magnetresonanzaufnahmen zeigen, dass sich Tetraederwürfel dichter als andere konvexe Körper ungeordnet packen lassen.},
author = {Engel, Michael},
faupublication = {no},
journal = {Physik Journal},
pages = {18-19},
peerreviewed = {unknown},
title = {{Brennpunkt}: {Volle} {Packung}},
volume = {9},
year = {2010}
}
@article{faucris.122146024,
author = {Masel, Joanna and Jansen, Vincent A. A. and Pöschel, Thorsten and Brilliantov, Nikolai V. and Frömmel, Cornelius},
doi = {10.1529/biophysj.104.039867},
faupublication = {no},
journal = {Biophysical Journal},
pages = {728-729},
peerreviewed = {Yes},
title = {{Prion} {Kinetics} (multiple letters)},
volume = {87},
year = {2004}
}
@article{faucris.109955164,
abstract = {About 20 years ago, Isaac Goldhirsch was one of the first to recognize that granular matter, behaving neither as a normal fluid nor as a normal solid, was not only an exotic terra
incognita for basic science, but is paradigmatic for a whole class of complex systems with irreversible interactions. This field became his passion at a time when he was already a
very successful, internationally renowned theoretical physicist. Certainly this helped to establish granular matter theory as a lively new branch of science. The very existence of a prominent new scientific journal ``Granular Matter'', entirely devoted to this field speaks for itself.},
author = {Pöschel, Thorsten and Wolf, Dietrich E.},
doi = {10.1007/s10035-012-0345-0},
faupublication = {yes},
journal = {Granular Matter},
peerreviewed = {Yes},
title = {{Isaac} {Goldhirsch}: a pioneer of granular matter theory},
year = {2012}
}
@incollection{faucris.218987059,
abstract = {Quantum statistics is a many body theory describing macroscopic matter. Let us first summarize concepts of classical many body theory and subsequently concepts of many body quantum theory, just what we need in the following. After this we will proceed to the simplest quantum statistical ensembles.},
address = {Cham},
author = {Ebeling, Werner and Pöschel, Thorsten},
booktitle = {Lectures on Quantum Statistics},
doi = {10.1007/978-3-030-05734-3_2},
faupublication = {yes},
isbn = {978-3-030-05733-6},
note = {CRIS-Team Scopus Importer:2019-05-28},
pages = {19-53},
peerreviewed = {unknown},
publisher = {Springer Verlag},
series = {Lecture Notes in Physics},
title = {{Elements} of quantum statistical theory},
volume = {953},
year = {2019}
}
@article{faucris.107691804,
abstract = {
Analogies between fluid flows and granular flows are useful because they pave the way for continuum treatments of granular media. However, in practice it is impossible to predict under what experimental conditions the dynamics of fluids and granulates are qualitatively similar. In the case of unsteadily driven systems no such analogy is known. For example, in a partially filled container subject to horizontal oscillations liquids slosh, whereas granular media of complex particles exhibit large-scale convection rolls. We here show that smooth monodisperse steel spheres exhibit liquidlike sloshing dynamics. Our findings highlight the role of particle material and geometry for the dynamics and phase transitions of the system.

},
author = {Avila Canellas, Kerstin and Steub, Laura and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.96.040901},
faupublication = {yes},
journal = {Physical Review E},
peerreviewed = {unknown},
title = {{Liquidlike} sloshing dynamics of monodisperse granulate},
volume = {96},
year = {2017}
}
@article{faucris.117059624,
abstract = {Patchy particles are a popular paradigm for the design and synthesis of nanoparticles and colloids for self-assembly. In "traditional" patchy particles, anisotropic interactions arising from patterned coatings, functionalized molecules, DNA, and other enthalpic means create the possibility for directional binding of particles into higher-ordered structures. Although the anisotropic geometry of nonspherical particles contributes to the interaction patchiness through van der Waals, electrostatic, and other interactions, how particle shape contributes entropically to self-assembly is only now beginning to be understood. The directional nature of entropic forces has recently been elucidated. A recently proposed theoretical framework that defines and quantifies directional entropic forces demonstrates the anisotropic that is, patchy nature of these emergent, attractive forces. Here we introduce the notion of entropically patchy particles as the entropic counterpart to enthalpically patchy particles. Using three example "families" of shapes, we show how to modify entropic patchiness by introducing geometric features to the particles via shape operations so as to target specific crystal structures assembled here with Monte Carlo simulations. We quantify the emergent entropic valence via a potential of mean force and torque. We show that these forces are on the order of a few k(B)T at intermediate densities below the onset of crystallization. We generalize these shape operations to shape anisotropy dimensions, in analogy with the anisotropy dimensions introduced for enthalpically patchy particles. Our findings demonstrate that entropic patchiness and emergent valence provide a way of engineering directional bonding into nanoparticle systems, whether in the presence or absence of additional, non-entropic forces.},
author = {Smith, Ross and Ahmed, N. Khalid and van Anders, Greg and Engel, Michael and Glotzer, Sharon C.},
doi = {10.1021/nn4057353},
faupublication = {no},
journal = {Acs Nano},
keywords = {shape entropy;patchy particles;superlattices},
month = {Jan},
pages = {931-940},
peerreviewed = {Yes},
title = {{Entropically} {Patchy} {Particles}: {Engineering} {Valence} through {Shape} {Entropy}},
volume = {8},
year = {2014}
}
@article{faucris.110739464,
abstract = {Expanding the library of self-assembled superstructures provides insight into the behaviour of atomic crystals and supports the development of materials with mesoscale order^{1, 2}. Here we build on recent findings of soft matter quasicrystals^{3, 4, 5, 6} and report a quasicrystalline binary nanocrystal superlattice that exhibits correlations in the form of partial matching rules reducing tiling disorder. We determine a three-dimensional structure model through electron tomography^{7, 8} and direct imaging of surface topography. The 12-fold rotational symmetry of the quasicrystal is broken in sublayers, forming a random tiling of rectangles, large triangles and small triangles with 6-fold symmetry. We analyse the geometry of the experimental tiling and discuss factors relevant for the stabilization of the quasicrystal. Our joint experimental–computational study demonstrates the power of nanocrystal superlattice engineering and further narrows the gap between the richness of crystal structures found with atoms and in soft matter assemblies.},
author = {Ye, Xingchen and Chen, Jun and Irrgang, M. Eric and Engel, Michael and Dong, Angang and Glotzer, Sharon C. and Murray, Christopher B.},
doi = {10.1038/nmat4759},
faupublication = {no},
journal = {Nature Materials},
peerreviewed = {Yes},
title = {{Quasicrystalline} {Nanocrystal} {Superlattice} with {Partial} {Matching} {Rules} {Xingchen} {Ye}, {Jun} {Chen}, {M}. {Eric} {Irrgang}, {Michael} {Engel}, {Angang} {Dong}, {Sharon} {C}. {Glotzer} & {Christopher} {B}. {Murray}},
year = {2016}
}
@inproceedings{faucris.109579404,
abstract = {Part of the optimization steps for additive manufacturing is related to the correct understanding of the mechanical behavior of the powder used in the process. Obtain this understanding based purely on experiments might be a difficult and sometimes prohibitive task. A particle-based numerical tool can provide critical information for correct understanding of powder deposition process. Numerical simulations through the Discrete Element Method (DEM) provide a useful mean to investigate the additive manufacturing process, given the possibility to study particle-scale information that are difficult to access experimentally. The characteristics of the recoated powder bed are investigated in the packed bed region and onto the manufactured part using PA12 commercial powder. Particle size distribution, contact and non-contact cohesive forces are incorporated in the numerical model. Furthermore, the non-spherical shape of real particles is taken explicitly into account in numerical simulations. A blade-type recoating system is used to form the powder bed and its roughness is calculated. Experimental measurements are performed by fringe projection. Several areas of the recoated powder layers can be scanned with this optical measurement method. Thus, the analyzed surface roughness can be compared with the simulated quantities to validate the numerical model. The sintered part is modelled as a prescribed rigid static region in the simulated system. The powder recoated in the sintered region may have different characteristics (packing, roughness) compared to the powder bed region. Recoating process is modelled using two different shapes for the sintered region. The amount of material recoated and the surface roughness are then calculated for the powder bed as well as for the sintered region},
author = {Schiochet Nasato, Daniel and Heinl, Martin and Hausotte, Tino and Pöschel, Thorsten},
booktitle = {International Conference on Particle based Methods},
date = {2017-09-26/2017-09-28},
editor = {V International Conference on Particle-based Methods – Fundamentals and Applications PARTICLES 2017},
faupublication = {yes},
keywords = {Granular Materials; DEM; Additive Manufacturing; Surface Roughness; Numerical simulation},
pages = {429-439},
peerreviewed = {unknown},
title = {{Numerical} and experimental study of the powder bed characteristics in the recoated bed of the additive manufacturing process},
venue = {Hannover},
year = {2017}
}
@article{faucris.213317910,
abstract = {The modeling of heterogeneous dynamic cell populations based on population balance equations is an important tool to describe the interaction between intracellular dynamics and population dynamics. However, the numerical simulation of such models remains challenging for models with high-dimensional intracellular dynamics, when these dynamics influence the growth rate of the cells. To cope with this challenge, we propose a hybrid simulation scheme based on the method of partial characteristics. We show that important features of the population density function, such as its moments or marginals, can be approximated by this scheme in a statistically converging way. In a case study with a population of differentiating cells, we illustrate how to obtain the growth dynamics of the individual subpopulations and deduce the extent of cell differentiation under a time-varying stimulus.},
author = {Waldherr, Steffen and Trennt, Philip and Hussain, Mubashir},
doi = {10.1109/LLS.2016.2615089},
faupublication = {yes},
journal = {Life Sciences Letters},
note = {EAM Import::2019-03-13},
pages = {9-12},
peerreviewed = {Yes},
title = {{Hybrid} {Simulation} of {Heterogeneous} {Cell} {Populations}},
volume = {2},
year = {2016}
}
@inproceedings{faucris.109716464,
author = {Engel, Michael},
booktitle = {CECAM Workshop on Self-assembly},
date = {2013-03-04/2013-03-06},
faupublication = {no},
peerreviewed = {unknown},
title = {{When} shapes collide: finding order in disorder},
venue = {École polytechnique fédérale de Lausanne},
year = {2013}
}
@article{faucris.116683864,
abstract = {Some dynamical properties for a time dependent Lorentz gas considering both the dissipative and non dissipative dynamics are studied. The model is described by using a four-dimensional nonlinear mapping. For the conservative dynamics, scaling laws are obtained for the behavior of the average velocity for an ensemble of non interacting particles and the unlimited energy growth is confirmed. For the dissipative case, four different kinds of damping forces are considered namely: (i) restitution coefficient which makes the particle experiences a loss of energy upon collisions; and in-flight dissipation given by (ii) F = -eta V-2; (iii) F = -eta V-mu with mu not equal 1 and mu not equal 2 and; (iv) F = -eta V, where eta is the dissipation parameter. Extensive numerical simulations were made and our results confirm that the unlimited energy growth, observed for the conservative dynamics, is suppressed for the dissipative case. The behaviour of the average velocity is described using scaling arguments and classes of universalities are defined. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.3697392]},
author = {Fregolente Mendes de Oliveira, Diego and Leonel, Edson D.},
doi = {10.1063/1.3697392},
faupublication = {yes},
journal = {Chaos},
peerreviewed = {Yes},
title = {{In}-flight and collisional dissipation as a mechanism to suppress {Fermi} acceleration in a breathing {Lorentz} gas},
volume = {22},
year = {2012}
}
@incollection{faucris.121828564,
address = {New York},
author = {Ribeiro Parteli, Eric Josef},
booktitle = {Encyclopedia of Planetary Landforms},
editor = {Hargitai H., Kereszturi, Ákos},
faupublication = {yes},
pages = {1 - 3},
peerreviewed = {unknown},
publisher = {Springer},
title = {{Rectilinear} {Dune}},
year = {2014}
}
@article{faucris.114662724,
abstract = {Downhill flows of granular matter colliding in the lowest point of a valley, may induce a selforganized jet. By means of a quasi two-dimensional experiment where fine grained sand flows in a vertically sinusoidally agitated cylinder, we show that the emergent jet, that is, a sheet of ejecta, does not follow the frequency of agitation but reveals subharmonic response. The order of the subharmonics is a complex function of the parameters of driving.},
author = {Kollmer, Jonathan and Pöschel, Thorsten},
doi = {10.1038/srep22520},
faupublication = {yes},
journal = {Scientific Reports},
peerreviewed = {Yes},
title = {{Subharmonic} instability of a self-organized granular jet},
volume = {6},
year = {2016}
}
@article{faucris.122137004,
abstract = {Granular pipe flows are characterized by intermittent behavior and large, potentially destructive solid fraction variations in the transport direction. By means of particle-based numerical simulations of gravity-driven flows in vertical pipes, we show that it is possible to obtain steady material transport by adding a helical texture to the inner-wall of the pipe. The helical texture leads to a more homogeneous mass flux along the pipe, prevents the emergence of large density waves and substantially reduces the probability of plug formation thus avoiding jamming of the particulate flow. We show that the granular mass flux Q through a pipe of diameter D with a helical texture of wavelength λ follows the equation Q = Q0·{1 - Bsin[arctan(2πD/λ)]}, where Q0 is the flow without helix, predicted from the well-known Beverloo equation. Our new expression yields, thus, a modification of the Beverloo equation with only one additional fit parameter, B, and describes the particle mass flux with the helical texture with excellent quantitative agreement with simulation results. Future application of the method proposed here has the potential to improve granular pipe flows in a broad range of processes without the need for energy input from any external source.},
author = {Verbücheln, Felix and Ribeiro Parteli, Eric Josef and Pöschel, Thorsten},
doi = {10.1039/c5sm00760g},
faupublication = {yes},
journal = {Soft Matter},
pages = {4295-4305},
peerreviewed = {Yes},
title = {{Helical} inner-wall texture prevents jamming in granular pipe flows},
volume = {11},
year = {2015}
}
@article{faucris.109906764,
abstract = {We investigate the cooling rate of a gas of inelastically interacting particles. When we assume velocity-dependent coefficients of restitution the material cools down slower than with constant restitution. This behavior might have a large influence to clustering and structure formation processes.},
author = {Schwager, Thomas and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.57.650},
faupublication = {no},
journal = {Physical Review E},
pages = {650-654},
peerreviewed = {Yes},
title = {{Coefficient} of normal restitution of viscous particles and cooling rate of granular gases},
volume = {57},
year = {1998}
}
@article{faucris.109177024,
abstract = {Cylindrical containers with a rotating bottom disk (so-called split-bottom geometry) are well established devices to shear granular materials in a continuous way, and to generate well-defined localized shear bands in the granular bed. When material composed of shape-anisotropic grains is sheared in such a container, a secondary flow is generated that leads to the formation of a considerable heap of material near the rotation center. We demonstrate that this effect can be found not only with prolate grains, as shown in a previous study, but also for oblate particle shapes. In addition, the quantitative influence of geometric and dynamic parameters is studied systematically. It is shown that the fill height of the container has considerable influence on the time scale for heap formation, but much less effect on the heap height. Results of numerical simulations agree with the experimental findings and provide insight in the particle dynamics.},
author = {Börzsönyi, Tamás and Fischer, David and Schiochet Nasato, Daniel and Pöschel, Thorsten and Stannarius, Ralf},
doi = {10.1088/1367-2630/18/11/113006},
faupublication = {yes},
journal = {New Journal of Physics},
peerreviewed = {Yes},
title = {{Heaping} and secondary flows in sheared granular materials},
volume = {18},
year = {2016}
}
@article{faucris.114384644,
abstract = {A recent conjecture in this Journal, concerning the existence of spiral stability phases in Hartley’s oscillator, is corroborated amply. We report numerically computed stability phase diagrams indicating precisely where spirals of periodicity and chaos may be found in several control planes of the system. In addition, we describe some remarkable parameter loops in control space which allow one to trace identical dynamical behaviors by tuning totally independent parameters.},
author = {Gallas, Jason A. and Gallas, Jason and Freire, J. G.},
doi = {10.1016/j.chaos.2013.12.007},
faupublication = {yes},
journal = {Chaos Solitons & Fractals},
pages = {129--134},
peerreviewed = {Yes},
title = {{Cyclic} organization of stable periodic and chaotic pulsations in {Hartley}’s oscillator},
volume = {59},
year = {2014}
}
@article{faucris.122142504,
abstract = {In dense, static, polydisperse granular media under isotropic pressure, the probability density and the correlations of particle-wall contact forces are studied. Furthermore, the probability density functions of the populations of pressures measured with different sized circular pressure cells are examined. The questions answered are: (i) What is the number of contacts that has to be considered so that the measured pressure lies within a certain error margin from its expectation value? (ii) What is the statistics of the pressure probability density as function of the size of the pressure cell? Astonishing non-random correlations between contact forces are evidenced that lead to a rapid decay of the width of the distribution and range at least 10-15 particle diameters. Finally, an experiment is proposed to tackle and better understand this issue. © 2010 Elsevier B.V. All rights reserved.},
author = {Müller, Micha-Klaus and Luding, Stefan and Pöschel, Thorsten},
doi = {10.1016/j.chemphys.2010.07.020},
faupublication = {yes},
journal = {Chemical Physics},
keywords = {DEM simulations; Dense static granular packings; Force and stress correlations; Pressure cells},
pages = {600-605},
peerreviewed = {Yes},
title = {{Force} statistics and correlations in dense granular packings},
volume = {375},
year = {2010}
}
@article{faucris.119744284,
abstract = {In a granular gas of rough particles the axis of rotation is shown to be correlated with the translational velocity of the particles. The average relative orientation of angular and linear velocities depends on the parameters which characterize the dissipative nature of the collision. We derive a simple theory for these correlations and validate it with numerical simulations for a wide range of coefficients of normal and tangential restitution. The limit of smooth spheres is shown to be singular: even an arbitrarily small roughness of the particles gives rise to orientational correlations. © 2007 The American Physical Society.},
author = {Brilliantov, Nikolai V. and Pöschel, Thorsten and Kranz, W. T. and Zippelius, A.},
doi = {10.1103/PhysRevLett.98.128001},
faupublication = {no},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Translations} and rotations are correlated in granular gases},
volume = {98},
year = {2007}
}
@article{faucris.116788144,
abstract = {Jammed packings of granular materials differ from systems normally described by statistical mechanics in that they are athermal. In recent years a statistical mechanics of static granular media has emerged where the thermodynamic temperature is replaced by a configurational temperature X which describes how the number of mechanically stable configurations depends on the volume. Four different methods have been suggested to measure X. Three of them are computed from properties of the Voronoi volume distribution, the fourth takes into account the contact number and the global volume fraction. This paper answers two questions using experimental binary disc packings: first we test if the four methods to measure compactivity provide identical results when applied to the same dataset. We find that only two of the methods agree quantitatively. This implies that at least two of the four methods are wrong. Secondly, we test if X is indeed an intensive variable; this becomes true only for samples larger than roughly 200 particles. This result is shown to be due to recently measured correlations between the particle volumes [Zhao et al., Europhys. Lett., 2012, 97, 34004].},
author = {Schröter, Matthias and Zhao, Song-Chuan},
doi = {10.1039/c3sm53176g},
faupublication = {no},
journal = {Soft Matter},
month = {Jan},
pages = {4208-4216},
peerreviewed = {Yes},
title = {{Measuring} the configurational temperature of a binary disc packing},
volume = {10},
year = {2014}
}
@article{faucris.213230408,
abstract = {Expanding the library of self-assembled superstructures provides insight into the behaviour of atomic crystals and supports the development of materials with mesoscale order. Here we build on recent findings of soft matter quasicrystals and report a quasicrystalline binary nanocrystal superlattice that exhibits correlations in the form of partial matching rules reducing tiling disorder. We determine a three-dimensional structure model through electron tomography and direct imaging of surface topography. The 12-fold rotational symmetry of the quasicrystal is broken in sublayers, forming a random tiling of rectangles, large triangles and small triangles with 6-fold symmetry. We analyse the geometry of the experimental tiling and discuss factors relevant for the stabilization of the quasicrystal. Our joint experimental-computational study demonstrates the power of nanocrystal superlattice engineering and further narrows the gap between the richness of crystal structures found with atoms and in soft matter assemblies.},
author = {Ye, Xingchen and Chen, Jun and Irrgang, M. Eric and Engel, Michael and Dong, Angang and Glotzer, Sharon C. and Murray, Christopher B.},
doi = {10.1038/nmat4759},
faupublication = {no},
journal = {Nature Materials},
note = {EAM Import::2019-03-13},
pages = {214-219},
peerreviewed = {Yes},
title = {{Quasicrystalline} nanocrystal superlattice with partial matching rules},
volume = {16},
year = {2017}
}
@article{faucris.119755944,
author = {Wu, Chuan-Yu and Pöschel, Thorsten},
doi = {10.1007/s10035-013-0441-9},
faupublication = {yes},
journal = {Granular Matter},
pages = {389-390},
peerreviewed = {Yes},
title = {{Micro}-mechanics and dynamics of cohesive particle systems},
volume = {15},
year = {2013}
}
@article{faucris.122896004,
abstract = {The coefficient of restitution of colliding viscoelastic spheres is known analytically as a complete series expansion in terms of the impact velocity where all (infinitely many) coefficients are known. While being analytically exact, this result is not suitable for applications in efficient event-driven molecular dynamics (eMD) or direct simulation Monte Carlo (DSMC) methods. Based on the analytic result, here we derive expressions for the coefficient of restitution that allow for application in efficient eMD and DSMC simulations of granular systems. © 2011 American Physical Society.},
author = {Müller, Patric and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.84.021302},
faupublication = {yes},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Collision} of viscoelastic spheres: {Compact} expressions for the coefficient of normal restitution},
volume = {84},
year = {2011}
}
@article{faucris.123556444,
abstract = {Convection, surface fluidization, spontaneous heap formation, and other effects are analyzed when a granular material is shaken vertically. The existence of a threshold for the Froude number Γ = Aω-0$//g is investigated, below which these effects cannot be observed. It is proved that there is no such threshold using computer simulation.},
author = {Pöschel, Thorsten and Schwager, Thomas and Salueña, Clara},
doi = {10.1103/PhysRevE.62.1361},
faupublication = {no},
journal = {Physical Review E},
pages = {1361-1367},
peerreviewed = {Yes},
title = {{Onset} of fluidization in vertically shaken granular material},
volume = {62},
year = {2000}
}
@inproceedings{faucris.116693324,
abstract = {Numerical simulations by means of the Discrete Element Method (DEM) can provide a helpful tool in the investigation of the packing behavior of powders. In this type of numerical simulations, the Newton’s equations of motion for every single particle in the system are solved by taking into account all forces and torques acting on it, both due to external fields and due to interactions with other particles in the system},
author = {Blümel, Christina and Ribeiro Parteli, Eric Josef and Schmidt, Jochen and Wirth, Karl Ernst and Peukert, Wolfgang and Pöschel, Thorsten},
booktitle = {85th Annual Meeting of the International Association of Applied Mathematics and Mechanics – GAMM 2014},
date = {2014-03-10/2014-03-14},
faupublication = {yes},
peerreviewed = {unknown},
title = {{Numerical} study of the packing density of fine powders by means of the {Discrete} {Element} {Method}},
year = {2014}
}
@book{faucris.109848904,
abstract = {A remarkably regular organization of spirals converging to a focal point in control parameter space was recently predicted and then observed in a nonlinear circuit containing two diodes. Such spiral organizations are relatively hard to observe experimentally because they usually emerge very compressed. Here we show that a circuit with a tunnel diode displays not one but two large spiral cascades. We show such cascades to exist over wide parameter ranges and, therefore, we expect them to be easier to observe experimentally. © Springer-Verlag Berlin Heidelberg 2013.},
author = {Francke, Ricardo and Pöschel, Thorsten and Gallas, Jason},
doi = {10.1007/978-3-642-34560-9-9},
faupublication = {yes},
isbn = {9783642345593},
pages = {161-177},
peerreviewed = {Yes},
title = {{Infinite} networks of hubs, spirals, and zig-zag patterns in self-sustained oscillations of a tunnel diode and of an erbium-doped fiber-ring laser},
volume = {459},
year = {2013}
}
@article{faucris.109978484,
abstract = {We report a numerical investigation of the structural properties of very large three-dimensional heaps of particles produced by ballistic deposition from extended circular dropping areas. Very large heaps are found to contain three new geometrical characteristics not observed before: they may have two external angles of repose, an internal angle of repose, and four distinct packing fraction (density) regions. Such characteristics are shown to be directly correlated with the size of the dropping zone. In addition, we also describe how noise during the deposition affects the final heap structure. © 2012 American Physical Society.},
author = {Topic, Nikola and Gallas, Jason and Pöschel, Thorsten},
doi = {10.1103/PhysRevLett.109.128001},
faupublication = {yes},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Nonuniformities} in the angle of repose and packing fraction of large heaps of particles},
volume = {109},
year = {2012}
}
@article{faucris.119285144,
abstract = {Using molecular dynamics simulation, we study the austenitic and the martensitic solid-solid phase transformation in the Fe-C system. Random alloys with C contents up to 1 at% are subjected to a heating/cooling cycle. The martensite and austenite phase transition temperatures can be determined from the hysteresis of the system volume with temperature. The martensite temperature decreases with C content, as in experiment. The influence of the C atom position on the phase transformation and the pathways of the transition are analyzed. The transformed austenite phase shows strong twinning. (C) 2013 Elsevier B.V. All rights reserved.},
author = {Gunkelmann, Nina and Wang, Binjun and Sak-Saracino, Emilia and Urbassek, Herbert M.},
doi = {10.1016/j.commatsci.2013.09.069},
faupublication = {no},
journal = {Computational Materials Science},
keywords = {Solid-solid phase transitions;Molecular dynamics simulation;Martensite;Fe-C alloy;Martensitic transformation},
pages = {399-404},
peerreviewed = {Yes},
title = {{Molecular}-dynamics study of the alpha <-> gamma phase transition in {Fe}-{C}},
volume = {82},
year = {2014}
}
@article{faucris.121008844,
abstract = {The AlPdMn quasicrystal approximants xi, xi', and xi'(n) of the 1.6nm decagonal phase and R, T, and T-n of the 1.2nm decagonal phase can be viewed as arrangements of cluster columns on two-dimensional tilings. We substitute the tiles by Penrose rhombs and show that alternative tilings can be constructed by a simple cut and projection formalism in three-dimensional hyperspace. It follows that in the approximants there is a phasonic degree of freedom, whose excitation results in the reshuffling of the clusters. We apply the tiling model for metadislocations, which are special textures of partial dislocations.},
author = {Engel, Michael and Trebin, Hans-Rainer},
doi = {10.1080/14786430500255211},
faupublication = {no},
journal = {Philosophical Magazine},
pages = {979-984},
peerreviewed = {Yes},
title = {{Tiling} models for metadislocations in {AlPdMn} approximants},
volume = {86},
year = {2006}
}
@article{faucris.216711456,
abstract = {The mechanical properties of granular materials change significantly in the presence of a wetting liquid which creates capillary bridges between the particles. This results e.g. in a reduced value of the volume fraction when a packing is prepared with added liquid. Here we use x-ray tomography to demonstrate that this change in mechanical properties is not accompanied by structural differences between dry and wet sphere packings when compared at the same volume fraction. We characterize the structure of the packings by the average numbers of contacts of each sphere < Z > and the shape isotropy of the Voronoi cells of the particles. Additionally, we show that the number of liquid bridges per sphere < B > is approximately equal to < Z > + 2, independent of the volume fraction of the packing. These findings will be helpful in guiding the development of both particle-based models and continuum mechanical descriptions of wet granular matter.},
author = {Weis, Simon and Schröder-Turk, Gerd and Schröter, Matthias},
doi = {10.1088/1367-2630/ab1517},
faupublication = {yes},
journal = {New Journal of Physics},
note = {CRIS-Team WoS Importer:2019-04-30},
peerreviewed = {Yes},
title = {{Structural} similarity between dry and wet sphere packings},
volume = {21},
year = {2019}
}
@article{faucris.123280564,
abstract = {We extend the Widom particle insertion method [B. Widom, J. Chem. Phys., 1963, 39, 2808-2812] to determine an upper bound s on the Edwards entropy in frictional hard-sphere packings. s corresponds to the logarithm of the number of mechanically stable configurations for a given volume fraction and boundary conditions. To accomplish this, we extend the method for estimating the particle insertion probability through the pore-size distribution in frictionless packings [V. Baranau, et al., Soft Matter, 2013, 9, 3361-3372] to the case of frictional particles. We use computer-generated and experimentally obtained three-dimensional sphere packings with volume fractions φ in the range 0.551-0.65. We find that s has a maximum in the vicinity of the Random Loose Packing Limit φ = 0.55 and decreases then monotonically with increasing φ to reach a minimum at φ = 0.65. Further on, s does not distinguish between real mechanical stability and packings in close proximity to mechanical stable configurations. The probability to find a given number of contacts for a particle inserted in a large enough pore does not depend on φ, but it decreases strongly with the contact number.},
author = {Schröter, Matthias and Baranau, Vasili and Zhao, Song-Chuan and Scheel, Mario and Tallarek, Ulrich},
doi = {10.1039/c6sm00567e},
faupublication = {yes},
journal = {Soft Matter},
pages = {3991-4006},
peerreviewed = {unknown},
title = {{Upper} bound on the {Edwards} entropy in frictional monodisperse hard-sphere packings},
volume = {12},
year = {2016}
}
@article{faucris.107686304,
abstract = {We create nearly perfect centimetric spheres of water by splitting a cavity consisting of two metal hemispheres coated with a hydrophobic paint and under-filled with liquid, while releasing the apparatus in free-fall. A high-speed camera captures how water spread on hydrophobic aluminum and polycarbonate plates perforated with cylindrical capillaries. We compare observations at the ZARM drop tower in Bremen with Lattice-Boltzmann numerical simulations of Frank, Perré and Li for the inertial phase of imbibition.},
author = {Steub, Laura and Kollmer, Jonathan and Paxson, Derek and Sack, Achim and Pöschel, Thorsten and Bartlett, John and Berman, Douglas and Richardson, Yaateh and Louge, Michel Y.},
doi = {10.1051/epjconf/201714016001},
faupublication = {yes},
journal = {EPJ Web of Conferences},
peerreviewed = {unknown},
title = {{Microgravity} spreading of water spheres on {Hydrophobic} capillary plates},
volume = {140},
year = {2017}
}
@article{faucris.119289984,
abstract = {The transport of sand and dust by wind is a potent erosional force, creates sand dunes and ripples, and loads the atmosphere with suspended dust aerosols. This paper presents an extensive review of the physics of wind-blown sand and dust on Earth and Mars. Specifically, we review the physics of aeolian saltation, the formation and development of sand dunes and ripples, the physics of dust aerosol emission, the weather phenomena that trigger dust storms, and the lifting of dust by dust devils and other small-scale vortices. We also discuss the physics of wind-blown sand and dune formation on Venus and Titan.},
author = {Ribeiro Parteli, Eric Josef and Kok, Jasper F. and Michaels, Timothy I. and Karam, Diana Bou},
doi = {10.1088/0034-4885/75/10/106901},
faupublication = {yes},
journal = {Reports on Progress in Physics},
peerreviewed = {Yes},
title = {{The} physics of wind-blown sand and dust},
volume = {75},
year = {2012}
}
@article{faucris.222689952,
abstract = {Synovial fluid is a lubricant of the synovial joint that shows remarkable tribological properties. These properties originate in the synergy between its components, with two of its major components, glycosaminoglycans (GAGs) and phospholipids (PLs), playing a major role in boundary and mixed lubrication regimes. All-atom molecular dynamic simulations were performed to investigate the way these components bond. Hyaluronic acid (HA) and chondroitin sulphate (CS) bonding with three types of lipids was tested. The results show that both glycosaminoglycans bind lipids at a similar rate, except for 1,2-d-ipalmitoyl-sn-glycero-3-phosphoethanolamine lipids, which bind to chondroitin at a much higher rate than to hyaluronan. The results suggest that different synovial fluid lipids may play a different role when binding to both hyaluronan and chondroitin sulphate. The presented results may help in understanding a process of lubrication of articular cartilage at a nanoscale level.},
author = {Beldowski, Piotr and Mazurkiewicz, Adam and Topoliński, Tomasz and Małek, Tomasz},
doi = {10.3390/ma12132060},
faupublication = {yes},
journal = {Materials},
keywords = {Chondroitin sulphate; Hyaluronic acid; Hydrogen bond; Molecular dynamics simulation; Osteoarthritis; Phospholipids; Synovial fluid; Water bridges},
note = {CRIS-Team Scopus Importer:2019-07-19},
peerreviewed = {Yes},
title = {{Hydrogen} and water bonding between glycosaminoglycans and phospholipids in the synovial fluid: {Molecular} dynamics study},
volume = {12},
year = {2019}
}
@article{faucris.221252277,
abstract = {In this paper, we explain the amphoteric character of the cartilage surface by studying a lipid bilayer model built from phospholipids. We examined the interfacial tension values and molecular dynamics simulation in solutions of varying pH. The effects of negative and positive charge density (or fixed charges) on the (cartilage/cartilage) friction coefficient were investigated. In physiological (or synovial) fluid, after the isoelectric point (pI), the curve of interfacial tension decreases rapidly as it reaches pH 7.4 and then approaches a constant value at higher pH. It was shown that the curve of the interfacial tension curve exhibits a maximum value at the isoelectric point with a Gaussian shape feature. The phospholipid bilayers facilitate an almost frictionless contact in the joint. Moreover, the slippage of the bilayer and the short-range repulsion between the surfaces of the negatively charged cartilage surfaces are the main determinants of the low frictional properties of the joint.},
author = {Janicka, Katarzyna and Beldowski, Piotr and Majewski, Tomasz and Urbaniak, Wieslaw and Petelska, Aneta D.},
doi = {10.3390/molecules24122248},
faupublication = {yes},
journal = {Molecules},
keywords = {Amphoteric articular cartilage; Interfacial tension; Molecular dynamics simulation; Phospholipids bilayers},
note = {CRIS-Team Scopus Importer:2019-06-25},
peerreviewed = {Yes},
title = {{The} amphoteric and hydrophilic properties of cartilage surface in mammalian joints: {Interfacial} tension and molecular dynamics simulation studies},
volume = {24},
year = {2019}
}
@article{faucris.109997844,
abstract = {We show that two basic mechanical processes, the collision of particles and rolling motion of a sphere on a plane, are intimately related. According to our recent findings, the restitution coefficient for colliding spherical particles ε, which characterizes the energy loss upon collision, is directly related to the rolling friction coefficient μ for a viscous sphere on a hard plane. We quantify both coefficients in terms of material constants which allows to determine either of them provided the other is known. This relation between the coefficients may give rise to a novel experimental technique to determine alternatively the coefficient of restitution or the coefficient of rolling friction.},
author = {Brilliantov, Nikolai and Pöschel, Thorsten},
doi = {10.1007/s100510051007},
faupublication = {no},
journal = {European Physical Journal B},
keywords = {81.05.Rm Porous materials; granular materials; 83.70.Fn Granular solids},
pages = {299-301},
peerreviewed = {Yes},
title = {{Rolling} as a "continuing collision"},
volume = {12},
year = {1999}
}
@article{faucris.119282284,
abstract = {
In this work, we examine theoretically the cooling dynamics of binary mixtures of spheres and rods. To this end, we introduce a generalized mean field analytical theory, which describes the free cooling behavior of the mixture. The relevant characteristic time scale for the cooling process is derived, depending on the mixture composition and the aspect ratio of the rods. We simulate mixtures of spherocylinders and spheres using a molecular dynamics algorithm implemented on graphics processing unit (GPU) architecture. We systematically study mixtures composed of spheres and rods with several aspect ratios and varying the mixture composition. A homogeneous cooling state, where the time dependence of the system’s intensive variables occurs only through a global granular temperature, is identified. We find cooling dynamics in excellent agreement with Haff’s law, when using an adequate time scale. Using the scaling properties of the homogeneous cooling dynamics, we estimated numerically the efficiency of the energy interchange between rotational and translational degrees of freedom for collisions between spheres and rods.

},
author = {Hidalgo, Raúl Cruz and Serero, Dan and Pöschel, Thorsten},
doi = {10.1063/1.4954670},
faupublication = {yes},
journal = {Physics of Fluids},
peerreviewed = {unknown},
title = {{Homogeneous} cooling of mixtures of particle shapes},
url = {http://www.mss.cbi.fau.de/content/uploads/Homogeneous_cooling_Physics_of_fluids_2016.pdf},
volume = {28},
year = {2016}
}
@article{faucris.109485684,
abstract = {Colloidal crystal structures with complexity and diversity rivaling atomic and molecular crystals have been predicted and obtained for hard particles by entropy maximization. However, thus far homochiral colloidal crystals, which are candidates for photonic metamaterials, are absent. Using Monte Carlo simulations we show that chiral polyhedra exhibiting weak directional entropic forces self-assemble either an achiral crystal or a chiral crystal with limited control over the crystal handedness. Building blocks with stronger faceting exhibit higher selectivity and assemble a chiral crystal with handedness uniquely determined by the particle chirality. Tuning the strength of directional entropic forces by means of particle rounding or the use of depletants allows for reconfiguration between achiral and homochiral crystals. We rationalize our findings by quantifying the chirality strength of each particle, both from particle geometry and potential of mean force and torque diagrams.},
author = {Engel, Michael and Damasceno, Pablo F. and Karas, Andrew S. and Schultz, Benjamin A. and Glotzer, Sharon C.},
doi = {10.1103/PhysRevLett.115.158303},
faupublication = {no},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Controlling} {Chirality} of {Entropic} {Crystals}},
volume = {115},
year = {2015}
}
@article{faucris.109168004,
abstract = {The original publication of the article contains an error in line number 8 of Algorithm 2. The correct version of the Algorithm 2 is provided in this erratum.},
author = {Strobl, Severin and Bannerman, Marcus and Pöschel, Thorsten},
doi = {10.1007/s40571-016-0111-x},
faupublication = {yes},
journal = {Computational Particle Mechanics},
peerreviewed = {Yes},
title = {{Erratum} to: {Stable} algorithm for event detection in event-driven particle dynamics: logical states},
url = {http://www.mss.cbi.fau.de/content/uploads/Erratum_stable_algorithm_Computational_Partical_Mechanics_2016.pdf},
year = {2016}
}
@article{faucris.109493164,
abstract = {Packings of hard polyhedra have been studied for centuries due to their mathematical aesthetic and more recently for their applications in fields such as nanoscience, granular and colloidal matter, and biology. In all these fields, particle shape is important for structure and properties, especially upon crowding. Here, we explore packing as a function of shape. By combining simulations and analytic calculations, we study three two- parameter families of hard polyhedra and report an extensive and systematic analysis of the densest known packings of more than 55 000 convex shapes. The three families have the symmetries of triangle groups ( icosahedral, octahedral, tetrahedral) and interpolate between various symmetric solids ( Platonic, Archimedean, Catalan). We find optimal ( maximum) packing- density surfaces that reveal unexpected richness and complexity, containing as many as 132 different structures within a single family. Our results demonstrate the importance of thinking about shape not as a static property of an object, in the context of packings, but rather as but one point in a higher- dimensional shape space whose neighbors in that space may have identical or markedly different packings. Finally, we present and interpret our packing results in a consistent and generally applicable way by proposing a method to distinguish regions of packings and classify types of transitions between them.},
author = {Engel, Michael and Chen, Elizabeth R. and Klotsa, Daphne and Damasceno, Pablo F. and Glotzer, Sharon C.},
doi = {10.1103/PhysRevX.4.011024},
faupublication = {no},
journal = {Physical Review X},
keywords = {Materials Science;Soft Matter},
peerreviewed = {unknown},
title = {{Complexity} in {Surfaces} of {Densest} {Packings} for {Families} of {Polyhedra}},
volume = {4},
year = {2014}
}
@article{faucris.117273904,
abstract = {For the study of crystal formation and dynamics, we introduce a simple two-dimensional monatomic model system with a parametrized interaction potential. We find in molecular dynamics simulations that a surprising variety of crystals, a decagonal, and a dodecagonal quasicrystal are self-assembled. In the case of the quasicrystals, the particles reorder by phason flips at elevated temperatures. During annealing, the entropically stabilized decagonal quasicrystal undergoes a reversible phase transition at 65% of the melting temperature into an approximant, which is monitored by the rotation of the de Bruijn surface in hyperspace.},
author = {Engel, Michael and Trebin, Hans-Rainer},
doi = {10.1103/PhysRevLett.98.225505},
faupublication = {no},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Self}-assembly of monatomic complex crystals and quasicrystals with a double-well interaction potential},
volume = {98},
year = {2007}
}
@article{faucris.109834164,
abstract = {Für die Entdeckung der Quasikristalle erhält Daniel Shechtman den Chemie-Nobelpreis 2011.},
author = {Engel, Michael and Trebin, Hans-Rainer and Roth, Johannes},
faupublication = {no},
journal = {Physik Journal},
pages = {31-34},
peerreviewed = {unknown},
title = {{Eine} unmögliche {Entdeckung} - {Nobelpreis} für {Quasikristalle}},
volume = {10},
year = {2011}
}
@article{faucris.122040204,
abstract = {We investigate the impact of a granular jet on a finite target by means of particle simulations. The resulting hydrodynamic fields are compared with theoretical predictions for the corresponding flow of an incompressible and rotation-free fluid. The degree of coincidence between the field obtained from the discrete granular system and the idealized continuous fluid flow depends on the characteristics of the granular system, such as granularity, packing fraction, inelasticity of collisions, friction and target size. In certain limits we observe a granular-continuum transition under which the geometric and dynamic properties of the particle jet and the fluid jet become almost identical. © 2014 Cambridge University Press.},
author = {Müller, Patric and Formella, Arno and Pöschel, Thorsten},
doi = {10.1017/jfm.2014.210},
faupublication = {yes},
journal = {Journal of Fluid Mechanics},
keywords = {complex fluids; granular media; jets},
pages = {601-626},
peerreviewed = {Yes},
title = {{Granular} jet impact: {Probing} the ideal fluid description},
volume = {751},
year = {2014}
}
@inproceedings{faucris.123895464,
author = {Engel, Michael},
booktitle = {Workshop: Open Space between Heavy Fermions and Quasicrystals},
date = {2015-11-17/2015-11-19},
faupublication = {no},
peerreviewed = {unknown},
title = {{Quasicrystals} on the computer: {The} role of complexity for crystal growth},
venue = {Nagoya},
year = {2015}
}
@article{faucris.114386624,
abstract = {Infinite cascades of periodicity hubs were predicted and very recently observed experimentally to organize stable oscillations of some dissipative flows. Here we describe the global mechanism underlying the genesis and organization of networks of periodicity hubs in control parameter space of a simple prototypical flow, namely a Rössler’s oscillator. We show that spirals associated with periodicity hubs emerge and accumulate at the folding of certain fractal-like sheaves of Shilnikov homoclinic bifurcations of a common saddle-focus equilibrium. The specific organization of hub networks is found to depend strongly on the interaction between the homoclinic orbits and the global structure of the underlying attractor.},
author = {Gallas, Jason and Vitolo, Renato and Glendinning, Paul},
doi = {10.1103/PhysRevE.84.016216},
faupublication = {yes},
journal = {Physical Review E},
pages = {016216},
peerreviewed = {Yes},
title = {{Global} structure of periodicity hubs in {Lyapunov} phase diagrams of dissipative flows},
volume = {84},
year = {2011}
}
@article{faucris.122549724,
author = {Engel, Michael and Glotzer, Sharon C.},
doi = {10.1038/nphys2903},
faupublication = {no},
journal = {Nature Physics},
pages = {185-186},
peerreviewed = {Yes},
title = {{Soft} matter: {A} triangular affair},
volume = {10},
year = {2014}
}
@article{faucris.122281984,
abstract = {The ability to mark bulk goods from different origins with RFID markers is of industrial interest, as such a method would improve the traceability of, e.g., cereals. However, due to a number of open technical questions, this method has not been utilized on a larger scale yet. This article studies the amount of segregation occurring between RFID markers, which are simulated as grain-sized plastic capsules, and marked wheat using two different setups. This segregation could occur during handling and transport due to the slightly different physical properties of the markers and the grains; it would then lead to erroneous results during subsequent quantitative analysis. In the first experiment, two samples of wheat, one marked with RFID dummies, were discharged in several steps from a test silo. A comparison of the marker concentration in the samples with the amount of associated wheat showed no discernible segregation. An additional statistical analysis allowed us to establish a relationship between the marker concentration and the error margin. In the second experiment, a mixture of wheat and markers was vertically shaken in a container, mimicking transport of wheat in large vessels. The position of the markers inside the container was determined by three-dimensional scans using x-ray tomography. We found that shaking induced some segregation due to sidewall-driven convection rolls, which indicated that the simulated markers were not optimally matched to the wheat grains. © 2014 American Society of Agricultural and Biological Engineers.},
author = {Schröter, Matthias and Steinmeier, Ulrich and Neudecker, Max and Witt, Annette and von Hörsten, Dieter},
doi = {10.13031/trans.57.10335},
faupublication = {no},
journal = {Transactions of the ASABE},
keywords = {Bulk good; Computed tomography; Marking; Shaker; Silo; Traceability},
pages = {555-563},
peerreviewed = {unknown},
title = {{Segregation} of simulated rfid markers during handling and transport of wheat},
volume = {57},
year = {2014}
}
@article{faucris.117057424,
abstract = {Small autonomous machines like biological cells or soft robots can convert energy input into control of function and form. It is desired that this behavior emerges spontaneously and can be easily switched over time. For this purpose we introduce an active matter system that is loosely inspired by biology and which we term an active colloidal cell. The active colloidal cell consists of a boundary and a fluid interior, both of which are built from identical rotating spinners whose activity creates convective flows. Similarly to biological cell motility, which is driven by cytoskeletal components spread throughout the entire volume of the cell, active colloidal cells are characterized by highly distributed energy conversion. We demonstrate that we can control the shape of the active colloidal cell and drive compartmentalization by varying the details of the boundary (hard vs. flexible) and the character of the spinners (passive vs. active). We report buckling of the boundary controlled by the pattern of boundary activity, as well as formation of core-shell and inverted Janus phase-separated configurations within the active cell interior. As the cell size is increased, the inverted Janus configuration spontaneously breaks its mirror symmetry. The result is a bubble-crescent configuration, which alternates between two degenerate states over time and exhibits collective migration of the fluid along the boundary. Our results are obtained using microscopic, non-momentum-conserving Langevin dynamics simulations and verified via a phase-field continuum model coupled to a Navier-Stokes equation.},
author = {Engel, Michael and Spellings, Matthew and Klotsa, Daphne and Sabrina, Syeda and Drews, Aaron M. and Nguyen, Nguyen H.P. and Bishop, Kyle J. M. and Glotzer, Sharon C.},
doi = {10.1073/pnas.1513361112},
faupublication = {no},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
keywords = {active matter;emergent pattern;confinement;colloids},
pages = {E4642-E4650},
peerreviewed = {Yes},
title = {{Shape} control and compartmentalization in active colloidal cells},
volume = {112},
year = {2015}
}
@article{faucris.106954804,
abstract = {Background: For many applications one wishes to decide whether a certain set of numbers originates from an equiprobability distribution or whether they are unequally distributed. Distributions of relative frequencies may deviate significantly from the corresponding probability distributions due to finite sample effects. Hence, it is not trivial to discriminate between an equiprobability distribution and non-equally distributed probabilities when knowing only frequencies. Results: Based on analytical results we provide a software tool which allows to decide whether data correspond to an equiprobability distribution. The tool is available at http://bioinf.charite.de/ equifreq/. Conclusions: Its application is demonstrated for the distribution of point mutations in coding genes. © 2003 Pöschel et al; licensee BioMed Central Ltd.},
author = {Pöschel, Thorsten and Frömmel, Cornelius and Gille, Christoph},
doi = {10.1186/1471-2105-4-58},
faupublication = {no},
journal = {Bmc Bioinformatics},
peerreviewed = {Yes},
title = {{Online} tool for the discrimination of equi-distributions},
url = {http://www.biomedcentral.com/1471-2105/4/58},
volume = {4},
year = {2003}
}
@article{faucris.109910724,
abstract = {The linear dashpot model for the inelastic normal force between colliding spheres leads to a constant coefficient of normal restitution, εn =const, which makes this model very popular for the investigation of dilute and moderately dense granular systems. For two frequently used models for the tangential interaction force we determine the coefficient of tangential restitution, εt, both analytically and by numerical integration of Newton's equation. Although εn =const for the linear-dashpot model, we obtain pronounced and characteristic dependences of the tangential coefficient on the impact velocity, εt = εt (g). The results may be used for event-driven simulations of granular systems of frictional particles. © 2008 The American Physical Society.},
author = {Becker, Volker and Schwager, Thomas and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.77.011304},
faupublication = {no},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Coefficient} of tangential restitution for the linear dashpot model},
volume = {77},
year = {2008}
}
@article{faucris.121646184,
abstract = {
Granulare Medien, wie Sand, Salz, Kohle oder Kaffeebohnen, lassen sich

durch vertikales Schütteln entmischen. In Abhängigkeit von der

Schüttelamplitude sammeln sich die größeren Teilchen entweder an der

Oberfläche (der sogenannte Paranuss-Effekt), oder sie sinken nach

unten (inverser Paranuss-Effekt). Mit Experimenten, Computersimula-

tionen und Theorie ist es jüngst gelungen, die zu diesem Verhalten

führenden Mechanismen zu identifizieren [1, 2].

},
author = {Schröter, Matthias and Ulrich, Stephan},
doi = {10.1002/piuz.200790081},
faupublication = {no},
journal = {Physik in unserer Zeit},
pages = {266-267},
peerreviewed = {No},
title = {{Der} {Paranuss}-{Effekt}},
url = {http://onlinelibrary.wiley.com/doi/10.1002/piuz.200790081/epdf},
volume = {38},
year = {2007}
}
@article{faucris.122021064,
abstract = {We study some dynamical properties for the problem of a charged particle in an electric field considering both the low velocity and relativistic cases. The dynamics for both approaches is described in terms of a two-dimensional and nonlinear mapping. The structure of the phase spaces is mixed and we introduce a hole in the chaotic sea to let the particles to escape. By changing the size of the hole we show that the survival probability decays exponentially for both cases. Additionally, we show for the relativistic dynamics, that the introduction of dissipation changes the mixed phase space and attractors appear. We study the parameter space by using the Lyapunov exponent and the average energy over the orbit and show that the system has a very rich structure with infinite family of self-similar shrimp shaped embedded in a chaotic region. © 2012 Elsevier B.V.},
author = {Fregolente Mendes de Oliveira, Diego and Leonel, Edson D.},
doi = {10.1016/j.physleta.2012.10.052},
faupublication = {yes},
journal = {Physics Letters A},
keywords = {Chaos; Parameter space; Shrimps; Survival probability},
pages = {3630-3637},
peerreviewed = {Yes},
title = {{Dynamical} properties for the problem of a particle in an electric field of wave packet: {Low} velocity and relativistic approach},
volume = {376},
year = {2012}
}
@incollection{faucris.218986315,
abstract = {In this chapter, we will introduce useful tools of Quantum Statistics. Most of them will be used in later chapters of this book to solve concrete problems. Our survey covers, of course, the most prominent methods such as density operators introduced by von Neumann and Landau, Wigner’s phase-space functions method, and Bogolyubov’s method of reduced density operators. Matsubara’s thermodynamical Green’s functions and real-time Green’s functions are important methods in the field of quantum plasmas but are discussed here only rather briefly.},
author = {Ebeling, Werner and Pöschel, Thorsten},
booktitle = {Lectures on Quantum Statistics},
doi = {10.1007/978-3-030-05734-3_4},
faupublication = {yes},
isbn = {978-3-030-05734-3},
note = {CRIS-Team Scopus Importer:2019-05-28},
pages = {91-140},
peerreviewed = {unknown},
publisher = {Springer Verlag},
series = {Lecture Notes in Physics},
title = {{Density} operators and other tools of quantum statistics},
volume = {953},
year = {2019}
}
@article{faucris.122569964,
abstract = {We investigate collective phenomena with rotationally driven spinners of concave shape. Each spinner experiences a constant internal torque in either a clockwise or counterclockwise direction. Although the spinners are modeled as hard, otherwise noninteracting rigid bodies, their active motion induces an effective interaction that favors rotation in the same direction. With increasing density and activity, phase separation occurs via spinodal decomposition, as well as self-organization into rotating crystals. We observe the emergence of cooperative, superdiffusive motion along interfaces, which can transport inactive test particles. Our results demonstrate novel phase behavior of actively rotated particles that is not possible with linear propulsion or in nondriven, equilibrium systems of identical hard particles.},
author = {Engel, Michael and Nguyen, Nguyen H.P. and Klotsa, Daphne and Glotzer, Sharon C.},
doi = {10.1103/PhysRevLett.112.075701},
faupublication = {no},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Emergent} {Collective} {Phenomena} in a {Mixture} of {Hard} {Shapes} through {Active} {Rotation}},
volume = {112},
year = {2014}
}
@article{faucris.122049224,
abstract = {At a pressure of around 13 GPa iron undergoes a structural phase transition from the bcc to the hexagonal close-packed phase. Atomistic simulations have provided important insights into this transition. However, while experiments in polycrystals show clear evidence that the alpha-epsilon transition is preceded by plasticity, simulations up to now could not detect any plastic activity occurring before the phase change. Here we study shock waves in polycrystalline Fe using an interatomic potential which incorporates the alpha-epsilon transition faithfully. Our simulations show that the phase transformation is preceded by dislocation generation at grain boundaries, giving a three-wave profile. The alpha-epsilon transformation pressure is much higher than the equilibrium transformation pressure but decreases slightly with increasing loading ramp time (decreasing strain rate). The transformed phase is mostly composed of hcp grains with large defect density. Simulated x-ray diffraction displays clear evidence for this hcp phase, with powder-diffraction-type patterns as they would be seen using current experimental setups.},
author = {Gunkelmann, Nina and Bringa, Eduardo M. and Tramontina, Diego R. and Ruestes, Carlos J. and Suggit, Matthew J. and Higginbotham, Andrew and Wark, Justin S. and Urbassek, Herbert M.},
doi = {10.1103/PhysRevB.89.140102},
faupublication = {yes},
journal = {Physical Review B},
peerreviewed = {Yes},
title = {{Shock} waves in polycrystalline iron: {Plasticity} and phase transitions},
volume = {89},
year = {2014}
}
@article{faucris.213304818,
abstract = {Starting from three-dimensional volume data of a granular packing, as, e.g., obtained by X-ray Computed Tomography, we discuss methods to first detect the individual particles in the sample and then analyze their properties. This analysis includes the pair correlation function, the volume and shape of the Voronoi cells, and the number and type of contacts formed between individual particles. We mainly focus on packings of monodisperse spheres, but we will also comment on other monoschematic particles such as ellipsoids and tetrahedra. This paper is accompanied by a package of free software containing all programs (including source code) and an example three-dimensional dataset which allows the reader to reproduce and modify all examples given.},
author = {Weis, Simon and Schröter, Matthias},
doi = {10.1063/1.4983051},
faupublication = {yes},
journal = {Review of Scientific Instruments},
note = {EAM Import::2019-03-13},
peerreviewed = {Yes},
title = {{Analyzing} {X}-ray tomographies of granular packings},
volume = {88},
year = {2017}
}
@article{faucris.107691584,
abstract = {
We describe the velocity distribution function of a granular gas of electrically charged particles by means of a Sonine polynomial expansion and study the decay of its granular temperature. We find a dependence of the first non trivial Sonine coefficient, *a*_{2} , on time through the value of temperature. In particular, we find a sudden drop of *a*_{2} when temperature approaches a characteristic value, T^{∗} , describing the electrostatic interaction. For lower values of T , the velocity distribution function becomes Maxwellian. The theoretical calculations agree well with numerical Direct Simulation Monte Carlo, to validate our theory.

},
author = {Takada, Satoshi and Serero, Dan and Pöschel, Thorsten},
doi = {10.1063/1.4993620},
faupublication = {yes},
journal = {Physics of Fluids},
peerreviewed = {unknown},
title = {{Homogeneous} cooling state of dilute granular gases of charged particles},
volume = {29},
year = {2017}
}
@article{faucris.118441224,
abstract = {We apply positron emission particle tracking (PEPT) to a gas-solid fluidized bed with injection of a secondary gas through a centrally arranged nozzle and present a method to compute stationary fluid-dynamic characteristics of the system from the trajectories of a test particle. In order to evaluate this non-invasive method we compare the field of density obtained by PEPT with the density obtained by a traditional, well-established and approved, yet invasive, measurement technique to find good agreement. Besides the penetration depth of the jet region and the opening angle of the jet which are inferred from the density field, we use PEPT to measure quantities whose measurement using traditional methods is rather sophisticated, including the residence time of particles in the jet region and the suspended phase, the coefficients of axial and radial dispersion and the material flux across the jet boundaries. We conclude that PEPT is a reliable and at the same time versatile technique to measure stationary fluid-dynamic properties of dynamical particle systems at spatial resolution only limited by the duration of the measurement.},
author = {Hensler, Timo and Tupy, Martin and Strer, Timo and Pöschel, Thorsten and Wirth, Karl-Ernst},
doi = {10.1016/j.powtec.2015.04.005},
faupublication = {yes},
journal = {Powder Technology},
keywords = {Dispersion coefficient; Fluidized bed; Measurement technology; Positron emission particle tracking; Residence time; Secondary gas injection},
pages = {113-122},
peerreviewed = {Yes},
title = {{Positron} emission particle tracking in fluidized beds with secondary gas injection},
volume = {279},
year = {2015}
}
@article{faucris.122032504,
abstract = {Scattering experiments are fundamental for structure analysis of matter on molecular, atomic and sub-atomic length scales. In contrast, it is not standard to demonstrate optical scattering experiments on the undergraduate level beyond simple diffraction gratings. We present an inexpensive Mie scattering setup manufactured with 3D printing and open hardware. The experiment can be used to determine the particle size in dilute monodisperse colloidal suspensions with surprisingly high accuracy and is, thus, suitable to demonstrate relations between scattering measurements and microscopic properties of particles within undergraduate lab course projects.},
author = {Scholz, Christian and Sack, Achim and Heckel, Michael and Pöschel, Thorsten},
doi = {10.1088/0143-0807/37/5/055305},
faupublication = {yes},
journal = {European Journal of Physics},
keywords = {Mie scattering; physics education experiments; 3D printing; open hardware},
peerreviewed = {Yes},
title = {{Inexpensive} {Mie} scattering experiment for the classroom manufactured by {3D} printing},
volume = {37},
year = {2016}
}
@article{faucris.110047124,
abstract = {The main precondition of simulating systems of hard particles by means of event-driven modeling is the assumption of instantaneous collisions. The aim of this paper is to quantify the deviation of event-driven modeling from the solution of Newton's equation of motion using a paradigmatic example: If a tennis ball is held above a basketball with their centers vertically aligned, and the balls are released to collide with the floor, the tennis ball may rebound at a surprisingly high speed. We show in this article that the simple textbook explanation of this effect is an oversimplification, even for the limit of perfectly elastic particles. Instead, there may occur a rather complex scenario including multiple collisions which may lead to a very different final velocity as compared with the velocity resulting from the oversimplified model. © 2011 American Physical Society.},
author = {Müller, Patric and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.83.041304},
faupublication = {yes},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Two}-ball problem revisited: {Limitations} of event-driven modeling},
volume = {83},
year = {2011}
}
@article{faucris.119295924,
abstract = {The temporal evolution of a water-sand interface driven by gravity is experimentally investigated. By means of a Fourier analysis of the evolving interface the growth rates are determined for the different modes appearing in the developing front. To model the observed behavior we apply the idea of the Rayleigh-Taylor instability for two stratified fluids. Carrying out a linear stability analysis we calculate the growth rates from the corresponding dispersion relations for finite and infinite cell sizes and compose those results with the experimental data. Alternatively, the situation of the sedimenting sand can be modeled by a two-dimensional cellular automaton. A qualitative similarity between that model and the experimental situation is obtained. © 2000 Elsevier Science B.V.},
author = {Schröter, Matthias and Engel, Andreas and Rehberg, Ingo and Lange, Adrian and Betat, André and Iori, Giulia and Völtz, Camilla},
faupublication = {no},
journal = {Physics Reports-Review Section of Physics Letters},
keywords = {05.45. - a},
pages = {117-138},
peerreviewed = {Yes},
title = {{Finger}-like patterns in sedimenting water-sand suspensions},
url = {https://www.scopus.com/inward/record.url?partnerID=HzOxMe3b&scp=0001468318&origin=inward},
volume = {337},
year = {2000}
}
@article{faucris.119363464,
abstract = {Based on citation data of biologists and physicists, we reiterate that trends in statistical indicators are not reliable to unambiguously blame mathematics for the existence or lack of paper citations. We further clarify that, contrary to claims in the Comment (Higginson and Fawcett 2016 *New J. Phys.*18 118003), a clear statistical correlation between the number of equations and the citation success is not possible because the data is too noisy and not reliable for identifying trends unambiguously. Concerning their conclusions, we stress the well-know fact in statistics that even if correlation could be found, it by no means imply causality. Concerning their conclusions, we stress the well-know fact in statistics that even if correlation could be found, it by no means implies causality. Accordingly, to discuss ways of increasing citation rates by suppressing or hiding equations in appendices cannot be justified with statistics, even less so when based on small sets of very noisy data.},
author = {Kollmer, Jonathan and Pöschel, Thorsten and Gallas, Jason},
doi = {10.1088/1367-2630/18/11/118004},
faupublication = {yes},
journal = {New Journal of Physics},
peerreviewed = {Yes},
title = {{Reply} to comment on ‘{Are} physicists afraid of mathematics?’},
volume = {18},
year = {2016}
}
@article{faucris.119200444,
abstract = {We study the global organization of oscillations in sigmoidal maps, a class of models which reproduces complex locking behaviors commonly observed in lasers, neurons, and other systems which display spiking, bursting, and chaotic sequences of spiking and bursting. We find periodic oscillations to emerge organized regularly according to the elusive Stern-Brocot tree, a symmetric and more general tree which contains the better-known asymmetric Farey tree as a sub-tree. The Stern-Brocot tree provides a natural and encompassing organization to classify nonlinear oscillations. The mathematical algorithm for generating both trees is exactly the same, differing only in the initial conditions. Such degeneracy suggests that the wrong tree might have been attributed to locking phenomena reported in some of the earlier works. © Copyright EPLA, 2012.},
author = {Freire, J. G. and Pöschel, Thorsten and Gallas, Jason},
doi = {10.1209/0295-5075/100/48002},
faupublication = {yes},
journal = {EPL - Europhysics Letters},
peerreviewed = {Yes},
title = {{Stern}-{Brocot} trees in spiking and bursting of sigmoidal maps},
volume = {100},
year = {2012}
}
@article{faucris.107385564,
abstract = {
We report evidence of a surprising systematic onset of periodic patterns in very tall piles of disks deposited randomly between rigid walls. Independently of the pile width, periodic structures are always observed in monodisperse deposits containing up to 107 disks. The probability density function of the lengths of disordered transient phases that precede the onset of periodicity displays an approximately exponential tail. These disordered transients may become very large when the channel width grows without bound. For narrow channels, the probability density of finding periodic patterns of a given period displays a series of discrete peaks, which, however, are washed out completely when the channel width grows.

},
author = {Topic, Nikola and Pöschel, Thorsten and Gallas, Jason},
doi = {10.1103/PhysRevLett.120.148002},
faupublication = {yes},
journal = {Physical Review Letters},
peerreviewed = {unknown},
title = {{Systematic} {Onset} of {Periodic} {Patterns} in {Random} {Disk} {Packings}},
volume = {120},
year = {2018}
}
@article{faucris.118198344,
abstract = {The resistance against rolling of a rigid cylinder on a flat viscous surface is investigated. We found that the rolling-friction coefficient reveals strongly non-linear dependence on the cylinder's velocity. For low velocity the rolling-friction coefficient rises with velocity due to increasing deformation rate of the surface. For larger velocity, however, it decreases with velocity according to decreasing contact area and deformation of the surface.},
author = {Pöschel, Thorsten and Schwager, Thomas and Brilliantov, Nikolai},
doi = {10.1007/s100510050840},
faupublication = {no},
journal = {European Physical Journal B},
pages = {169-174},
peerreviewed = {Yes},
title = {{Rolling} friction of a hard cylinder on a viscous plane},
volume = {10},
year = {1999}
}
@article{faucris.109944604,
abstract = {The hydrodynamics of granular gases of viscoelastic particles were derived. Collisions of viscoelastic particles were characterized by an impact velocity dependent coefficient of restitution. The Chapman-Enskog approach was used together with an adiabatic approximation for the velocity distribution function, which assumes that the shape of the velocity distribution function follows adiabatically the decaying temperature. Numerical solutions for temperature T(t) and for the second Sonine coefficient a(t) were compared with the corresponding adiabatic approximations.},
author = {Brilliantov, Nikolai and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.67.061304},
faupublication = {no},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Hydrodynamics} and transport coefficients for dilute granular gases},
url = {http://journals.aps.org/pre/abstract/10.1103/PhysRevE.67.061304},
volume = {67},
year = {2003}
}
@article{faucris.212753550,
abstract = {Quasicrystals are frequently encountered in condensed matter. They are important candidates for equilibrium phases from the atomic scale to the nanoscale. Here, we investigate the computational self-assembly of four quasicrystals in a single model system of identical particles interacting with a tunable isotropic pair potential. We reproduce a known icosahedral quasicrystal and report a decagonal quasicrystal, a dodecagonal quasicrystal, and an octagonal quasicrystal. The quasicrystals have low coordination number or occur in systems with mesoscale density variations. We also report a network gel phase.},
author = {Damasceno, Pablo F. and Glotzer, Sharon C. and Engel, Michael},
doi = {10.1088/1361-648X/aa6cc1},
faupublication = {yes},
journal = {Journal of Physics: Condensed Matter},
note = {EAM Import::2019-03-08},
peerreviewed = {Yes},
title = {{Non}-close-packed three-dimensional quasicrystals},
volume = {29},
year = {2017}
}
@article{faucris.122915804,
abstract = {A representation of the genetic code as a six-dimensional Boolean hypercube is described. This structure is the result of the hierarchical order of the interaction energies of the bases in codon-anticodon recognition. In this paper it is applied to study molecular evolution in vivo and in vitro. In the first case we compared aligned positions in homologous protein sequences and found two different behaviors: (a) There are sites in which the different amino acids may be explained by one or two 'attractor nodes' (coding for the dominating amino acid(s)) and their one-bit neighbors in the codon hypercube; and (b) There are sites in which the amino acids correspond to codons located in closed paths in the hypercube. In the second case we studied the 'Sexual PCR' experiment described by Stemmer and found that the success of this combination of usual PCR and recombination is in part due to the Gray code structure of the genetic code.},
author = {Jiménez-Montaño, Miguel A. and de la Mora-Basáñez, Carlos R. and Pöschel, Thorsten},
doi = {10.1016/0303-2647(96)01605-X},
faupublication = {no},
journal = {Biosystems},
keywords = {Genetic code; In vitro and in vivo; Molecular evolution; Six dimensional Boolean hypercube},
pages = {117-125},
peerreviewed = {Yes},
title = {{The} hypercube structure of the genetic code explains conservative and non-conservative aminoacid substitutions in vivo and in vitro},
volume = {39},
year = {1996}
}
@article{faucris.114386844,
abstract = {Event-driven particle dynamics is a fast and precise method to simulate particulate systems of all scales. In this work it is demonstrated that, despite the high accuracy of the method, the finite machine precision leads to simulations entering invalid states where the dynamics are undefined. A general event-detection algorithm is proposed which handles these situations in a stable and efficient manner. This requires a definition of the dynamics of invalid states and leads to improved algorithms for event-detection in hard-sphere systems.},
author = {Bannerman, Marcus and Strobl, Severin and Formella, Arno and Pöschel, Thorsten},
doi = {10.1007/s40571-014-0021-8},
faupublication = {yes},
journal = {Computational Particle Mechanics},
pages = {191--198},
peerreviewed = {Yes},
title = {{Stable} algorithm for event detection in event-driven particle dynamics},
volume = {1},
year = {2014}
}
@article{faucris.122031184,
abstract = {Strong shock waves create not only plasticity in Fe, but also phase transform the material from its bcc phase to the high-pressure hcp phase. We perform molecular-dynamics simulations of large, 8-million atom nanocrystalline Fe samples to study the interplay between these two mechanisms. We compare results for a potential that describes dislocation generation realistically but excludes phase change with another which in addition faithfully features the bcc -> hcp transformation. With increasing shock strength, we find a transition from a two-wave structure (elastic and plastic wave) to a three-wave structure (an additional phase-transformation wave), in agreement with experiment. Our results demonstrate that the phase transformation is preceded by dislocation generation at the grain boundaries (GBs). Plasticity is mostly given by the formation of dislocation loops, which cross the grains and leave behind screw dislocations. We find that the phase transition occurs for a particle velocity between 0.6 and 0.7 km s(-1). The phase transition takes only about 10 ps, and the transition time decreases with increasing shock pressure.},
author = {Gunkelmann, Nina and Tramontina, Diego R. and Bringa, Eduardo M. and Urbassek, Herbert M.},
doi = {10.1088/1367-2630/16/9/093032},
faupublication = {yes},
journal = {New Journal of Physics},
keywords = {shock wave;iron;molecular dynamics;solid-solid transitions;plasticity;dislocations},
peerreviewed = {Yes},
title = {{Interplay} of plasticity and phase transformation in shock wave propagation in nanocrystalline iron},
volume = {16},
year = {2014}
}
@article{faucris.123696144,
author = {Brey, Javier and Goldhirsch, Isaac and Pöschel, Thorsten},
faupublication = {yes},
journal = {European Physical Journal-Special Topics},
peerreviewed = {Yes},
title = {{Granular} {Gases}: {Beyond} the {Dilute} {Limit}},
volume = {179},
year = {2009}
}
@article{faucris.109997624,
abstract = {The oscillation of a spring may be attenuated by means of a granular damper. In difference to viscous dampers, the amplitude decays nearly linearly in time up to a finite value, from there on it decays much slower. We quantitatively explain the linear decay, which was a long-standing question. © IOP Publishing and Deutsche Physikalische Gesellschaft.},
author = {Kollmer, Jonathan and Sack, Achim and Heckel, Michael and Pöschel, Thorsten},
doi = {10.1088/1367-2630/15/9/093023},
faupublication = {yes},
journal = {New Journal of Physics},
peerreviewed = {Yes},
title = {{Relaxation} of a spring with an attached granular damper},
volume = {15},
year = {2013}
}
@article{faucris.122089924,
abstract = {We study the formation of capillary bridges between micrometer-sized glass spheres immersed in a binary liquid mixture using bright field and confocal microscopy. The bridges form upon heating due to the preferential wetting of the hydrophilic glass surface by the water-rich phase. If the system is cooled below the demixing temperature, the bridges disappear within a few seconds by intermolecular diffusion. Thus, this system oilers the opportunity to switch the bridges on and off and to tune precisely the bridge volume by altering the temperature in a convenient range. We measure the bridge geometry as a function or the temperature from bright field images and calculate the cohesive force. We discuss the influence of the solvent composition on the bridge formation temperature, the strength of the capillary force. and the bridge volume growth rate. Furthermore, we find that the onset of bridge formation coincides with the water-lutidine bulk coexistence curve.},
author = {Schröter, Matthias and Gögelein, Christoph and Brinkmann, Martin and Herminghaus, Stephan},
doi = {10.1021/la103062s},
faupublication = {no},
journal = {Langmuir},
pages = {17184-17189},
peerreviewed = {Yes},
title = {{Controlling} the {Formation} of {Capillary} {Bridges} in {Binary} {Liquid} {Mixtures}},
volume = {26},
year = {2010}
}
@article{faucris.109809304,
abstract = {A granular gas in gravity heated from below develops a certain stationary density profile. When the heating is switched off, the granular gas collapses. We investigate the process of sedimentation using computational hydrodynamics, based on the Jenkins-Richman theory, and find that the process is significantly more complex than generally acknowledged. In particular, during its evolution, the system passes several stages which reveal distinct spatial regions of inertial (supersonic) and diffusive (subsonic) dynamics. During the supersonic stages, characterized by Mach>1, the system develops supersonic shocks which are followed by a steep front of the hydrodynamic fields of temperature and density, traveling upward.},
author = {Almazán Torres, Lidia and Serero, Dan and Salueña, Clara and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.91.062214},
faupublication = {yes},
journal = {Physical Review E - Statistical, Nonlinear, and Soft Matter Physics},
keywords = {granular gas},
peerreviewed = {Yes},
title = {{Self}-organized shocks in the sedimentation of a granular gas},
volume = {91},
year = {2015}
}
@article{faucris.110038324,
abstract = {The most striking phenomenon in the dynamics of granular gases is the formation of clusters and other structures. We investigate a gas of dissipatively colliding particles with a velocity dependent coefficient of restitution where cluster formation occurs as a transient phenomenon. Although for small impact velocity the particles collide elastically, surprisingly the temperature converges to zero. © 2005 IOP Publishing Ltd.},
author = {Pöschel, Thorsten and Brilliantov, Nikolai V. and Schwager, Thomas},
doi = {10.1088/0953-8984/17/24/021},
faupublication = {no},
journal = {Journal of Physics: Condensed Matter},
peerreviewed = {Yes},
title = {{Transient} clusters in granular gases},
volume = {17},
year = {2005}
}
@article{faucris.119404164,
abstract = {
The theory of homogeneously driven granular gases of hard particles predicts that the stationary state is characterized by a velocity distribution function with overpopulated high-energy tails as compared to the exponential decay valid for molecular gases. While this fundamental theoretical result was confirmed by numerous numerical simulations, an experimental confirmation is still missing. Using self-rotating active granular particles, we find a power-law decay of the velocity distribution whose exponent agrees well with the theoretic prediction.

},
author = {Scholz, Christian and Pöschel, Thorsten},
doi = {10.1103/PhysRevLett.118.198003},
faupublication = {yes},
journal = {Physical Review Letters},
peerreviewed = {unknown},
title = {{Velocity} distribution of a homogeneously driven two-dimensional granular gas},
volume = {118},
year = {2017}
}
@article{faucris.109876404,
abstract = {Antiperiodic oscillations forming infinite cascades of spirals were recently found experimentally and numerically in the control parameter space of an autonomous electronic circuit. They were discovered while recording one specific voltage of the circuit. Here, we show that such regular self-organization may be measured in any of the four variables of the circuit. Although the relative size of individual phases, their boundaries and the number of peaks of each characteristic oscillation depends on the physical quantity used to record them, the global structural organization of the complex phase diagrams is an invariant of the circuit. Tunable families of antiperiodic oscillations cast fresh light on new intricate behavior of nonlinear systems and open the possibility of studying hitherto unobserved phenomena.},
author = {Freire, J. G. and Cabeza, C. and Marti, A. C. and Pöschel, Thorsten and Gallas, Jason},
doi = {10.1140/epjst/e2014-02299-2},
faupublication = {yes},
journal = {European Physical Journal: Special Topics},
pages = {2857-2867},
peerreviewed = {Yes},
title = {{Self}-organization of antiperiodic oscillations},
volume = {223},
year = {2014}
}
@article{faucris.119357304,
abstract = {The relationship between colloidal building blocks-and their assemblies is an active field of research. As a strategy for targeting novel Crystal structures, we examine the use,of Voronoi particles, which are hard, space-filling particles in the shape of Voronoi cells of a target Structure. Although Voronoi particles stabilize their target structure in the limit of high pressure by construction, the thermodynamic assembly of the same structure at moderate pressure, close to the onset of crystallization, is not guaranteed. Indeed, we find that a more symmetric crystal is often-preferred due to additional entropic contributions arising from configurational or occupational degeneracy. We characterize the assembly behavior of the Voronoi particles in terms of the symmetries of the building blocks as well as the symmetries of crystal structures and demonstrate how controlling the degeneracies through a modification of particle shape and field-directed assembly can significantly improve the assembly propensity.},
author = {Schultz, Benjamin A. and Damasceno, Pablo F. and Engel, Michael and Glotzer, Sharon C.},
doi = {10.1021/nn507490j},
faupublication = {no},
journal = {Acs Nano},
keywords = {self-assembly;entropic forces;Monte Carlo simulation;hard particles;particle design},
pages = {2336-2344},
peerreviewed = {Yes},
title = {{Symmetry} {Considerations} for the {Targeted} {Assembly} of {Entropically} {Stabilized} {Colloidal} {Crystals} via {Voronoi} {Particles}},
volume = {9},
year = {2015}
}
@article{faucris.122877744,
abstract = {The dynamics of dissipative soft-sphere gases obeys Newton's equations of motion, which are commonly solved numerically by (force-based) Molecular Dynamics (MD) schemes. With the assumption of instantaneous, pairwise collisions, the simulation can be accelerated considerably using event-driven MD, where the coefficient of restitution is derived from the interaction force between particles. Recently it was shown, however, that this approach may fail dramatically, that is, the obtained trajectories deviate significantly from the ones predicted by Newton's equations. In this paper, we generalize the concept of the coefficient of restitution and derive a numerical scheme which, in the case of dilute systems and frictionless interaction, allows us to perform highly efficient event-driven MD simulations even for noninstantaneous collisions. We show that the particle trajectories predicted by our scheme agree perfectly with the corresponding (force-based) MD, except for a short transient period whose duration corresponds to the duration of the contact. Thus, the new algorithm solves Newton's equations of motion like force-based MD while preserving the advantages of event-driven simulations. © 2013 American Physical Society.},
author = {Müller, Patric and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.87.033301},
faupublication = {yes},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Event}-driven molecular dynamics of soft particles},
volume = {87},
year = {2013}
}
@article{faucris.122143824,
abstract = {We investigate the structure and adsorption of amphiphilic molecules at planar walls modified by tethered chain molecules using density functional theory. The molecules are modeled as spheres composed of a hydrophilic and hydrophobic part. The pinned chains are treated as tangentially jointed spheres that can interact with fluid molecules via orientation-dependent forces. Our density functional approach involves fundamental measure theory, thermodynamic perturbation theory for chains, and a mean-field approximation for describing the anisotropic interactions. We study the adsorption of the particles, focusing on the competition between the external field (due to the surface and due to attached chain molecules) and the interaction-induced ordering phenomena. © 2013 American Chemical Society.},
author = {Borówko, M. and Pöschel, Thorsten and Sokolowski, Stefan and Staszewski, T.},
doi = {10.1021/jp3105979},
faupublication = {yes},
journal = {Journal of Physical Chemistry B},
pages = {1166-1175},
peerreviewed = {Yes},
title = {{Janus} particles at walls modified with tethered chains},
volume = {117},
year = {2013}
}
@phdthesis{faucris.109837464,
abstract = {Complex crystals and quasicrystals are ordered states of matter with very large or even infinite unit cells. Their particle dynamics and defects differ significantly from what is known for simple crystals: Local rearrangements – phason flips – and new types of dislocations are consequences of the structural complexity. In order to understand their behavior at an elementary level, we introduce three model systems in one and two dimensions. The systems are studied analytically and with numerical simulations. (i) The structure factors of the dynamic Fibonacci chain are computed with high resolution. They show a characteristic broadening of the phonon dispersion relation. The particle motion in real space reveals soliton and breather modes, closely connected to phason flips. (ii) Using a tiling model for the intermetallic system AlPdMn, experimental observations of metadislocations and the collective particle dynamics are explained. The Burgers vectors of stable dislocations are derived from energy considerations. (iii) In the Lennard-Jones-Gauss system a surprising variety of two-dimensional complex crystals as well as a decagonal and two dodecagonal quasicrystals are grown. The particles reorder by phason flips at elevated temperatures. During annealing, the entropically stabilized quasicrystals undergo reversible phase transitions into complex crystals. Competing interparticle distances seem to favor structural complexity. With the Lennard-Jones-Gauss system the growth, equilibrium dynamics, and defects of quasicrystals and complex crystals can be studied in simulations for the first time.},
author = {Engel, Michael},
doi = {10.18419/opus-4824},
faupublication = {no},
peerreviewed = {automatic},
school = {Friedrich-Alexander-Universität Erlangen-Nürnberg},
title = {{Dynamics} and {Defects} of {Complex} {Crystals} and {Quasicrystals}: {Perspectives} from {Simple} {Model} {Systems}},
year = {2008}
}
@article{faucris.119756164,
abstract = {The evolution of a pile of granular material is investigated by molecular dynamics using a new model including nonsphericity of the particles instead of introducing static friction terms. The angle of repose of the piles as well as the avalanche statistics gathered by the simulation agree with experimental results. The angle of repose of the pile is determined by the shape of the grains. Our results are compared with simulations using spherical grains and static friction. © 1994.},
author = {Buchholtz, Volkhard and Pöschel, Thorsten},
doi = {10.1016/0378-4371(94)90467-7},
faupublication = {no},
journal = {Physica A-Statistical Mechanics and Its Applications},
pages = {390-401},
peerreviewed = {Yes},
title = {{Numerical} investigations of the evolution of sandpiles},
volume = {202},
year = {1994}
}
@article{faucris.109906984,
abstract = {The coefficient of restitution of a spherical particle in contact with a flat plate is investigated as a function of the impact velocity. As an experimental observation we notice nontrivial (non-Gaussian) fluctuations of the measured values. For a fixed impact velocity, the probability density of the coefficient of restitution, p, is formed by two exponential functions (one increasing, one decreasing) of different slope. This behavior may be explained by a certain roughness of the particle which leads to energy transfer between the linear and rotational degrees of freedom. © 2011 American Physical Society.},
author = {Montaine, Marina and Heckel, Michael and Kruelle, Christof and Schwager, Thomas and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.84.041306},
faupublication = {yes},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Coefficient} of restitution as a fluctuating quantity},
volume = {84},
year = {2011}
}
@article{faucris.109829104,
author = {Brilliantov, Nikolai V. and Albers, Nicole and Spahn, Frank and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.87.039904},
faupublication = {yes},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Erratum}: {Collision} dynamics of granular particles with adhesion ({Physical} {Review} {E} (2007) 76 (051302))},
volume = {87},
year = {2013}
}
@article{faucris.117060064,
abstract = {Current trends in parallel processors call for the design of efficient massively parallel algorithms for scientific computing. Parallel algorithms for Monte Carlo simulations of thermodynamic ensembles of particles have received little attention because of the inherent serial nature of the statistical sampling. In this paper, we present a massively parallel method that obeys detailed balance and implement it for a system of hard disks on the GPU. We reproduce results of serial high-precision Monte Carlo runs to verify the method. This is a good test case because the hard disk equation of state over the range where the liquid transforms into the solid is particularly sensitive to small deviations away from the balance conditions. On a Tesla K20, our GPU implementation executes over one billion trial moves per second, which is 148 times faster than on a single Intel Xeon E5540 CPU core, enables 27 times better performance per dollar, and cuts energy usage by a factor of 13. With this improved performance we are able to calculate the equation of state for systems of up to one million hard disks. These large system sizes are required in order to probe the nature of the melting transition, which has been debated for the last forty years. In this paper we present the details of our computational method, and discuss the thermodynamics of hard disks separately in a companion paper. (C) 2013 Elsevier Inc. All rights reserved.},
author = {Engel, Michael and Anderson, Joshua A. and Jankowski, Eric and Grubb, Thomas L. and Glotzer, Sharon C.},
doi = {10.1016/j.jcp.2013.07.023},
faupublication = {no},
journal = {Journal of Computational Physics},
keywords = {Monte Carlo;Parallel algorithm;Detailed balance;GPGPU;CUDA;Hard disk system},
pages = {27-38},
peerreviewed = {Yes},
title = {{Massively} parallel {Monte} {Carlo} for many-particle simulations on {GPUs}},
volume = {254},
year = {2013}
}
@article{faucris.116791664,
abstract = {Three fundamental segregation and pattern formation processes are known in granular mixtures in a rotating cylindrical drum: radial segregation, axial banding, and coarsening of the band pattern. While the mechanism for the first effect is well understood and for the second effect, several models have been proposed, the long-term coarsening mechanism remained unexplained so far. We demonstrate that the unidirectional flow between the bands in an axially segregated pattern is driven by small differences in size of the small beads at the band edges. Due to a process of microsegregation inside each band of small particles, which was so far unrecognized, this difference in diameter will be effective in all experiments with polydisperse beads. In consequence the stability of individual bands can be easily controlled by minor alterations of their composition. Our results make evident that a new mechanism as the driving force behind the axial particle flow has to be sought. We suggest possible hypotheses for such a mechanism.},
author = {Schröter, Matthias and Finger, Tilo and Stannarius, Ralf},
doi = {10.1088/1367-2630/17/9/093023},
faupublication = {no},
journal = {New Journal of Physics},
keywords = {axial segregation; coarsening dynamics; granular mixtures; microsegregation; rotating drum},
peerreviewed = {Yes},
title = {{The} mechanism of long-term coarsening of granular mixtures in rotating drums},
volume = {17},
year = {2015}
}
@inproceedings{faucris.123097744,
author = {Engel, Michael},
booktitle = {22nd Congress International Union of Crystallography},
date = {2011-08-22/2011-08-30},
faupublication = {no},
peerreviewed = {unknown},
title = {{Unusual} crystal structures with hard polyhedra},
venue = {Madrid},
year = {2011}
}
@article{faucris.109923264,
author = {Brilliantov, Nikolai V. and Pöschel, Thorsten},
doi = {10.1209/epl/i2006-10099-3},
faupublication = {no},
journal = {EPL - Europhysics Letters},
peerreviewed = {Yes},
title = {{Erratum}: {Breakdown} of the sonine expansion for the velocity distribution of granular gases ({Europhysics} {Letters} (2006) 74:3 (424-430) )},
volume = {75},
year = {2006}
}
@article{faucris.109805124,
abstract = {We consider the motion of an aspherical inelastic particle of dumbbell type bouncing repeatedly on a horizontal flat surface. The coefficient of restitution of such a particle depends not only on material properties and impact velocity but also on the angular orientation at the instant of the collision whose variance is considerable, even for small eccentricity. Assuming random angular orientation of the particle at the instant of contact we characterize the measured coefficient of restitution as a fluctuating quantity and obtain a wide probability density function including a finite probability for negative values of the coefficient of restitution. This may be understood from the partial exchange of translational and rotational kinetic energy.},
author = {Glielmo, Aldo and Gunkelmann, Nina and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.90.052204},
faupublication = {yes},
journal = {Physical Review E - Statistical, Nonlinear, and Soft Matter Physics},
peerreviewed = {Yes},
title = {{Coefficient} of restitution of aspherical particles},
volume = {90},
year = {2014}
}
@article{faucris.116723904,
abstract = {Using sedimentation to obtain precisely controlled packings of noncohesive spheres, we find that the volume fraction phi(RLP) of the loosest mechanically stable packing is in an operational sense well defined by a limit process. This random loose packing volume fraction decreases with decreasing pressure p and increasing interparticle friction coefficient mu. Using x-ray tomography to correct for a container boundary effect that depends on particle size, we find for rough particles in the limit p -> 0 a new lower bound, phi(RLP)=0.550 +/- 0.001.},
author = {Schröter, Matthias and Jerkins, Melissa and Swinney, Harry L. and Saadatfar, Mohammad and Aste, T. and Senden, T.J.},
doi = {10.1103/PhysRevLett.101.018301},
faupublication = {no},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Onset} of mechanical stability in random packings of frictional spheres},
volume = {101},
year = {2008}
}
@article{faucris.120500204,
abstract = {The coefficient of restitution may be determined from the sound signal emitted by a sphere bouncing repeatedly off the ground. Although there is a large number of publications exploiting this method, so far, there is no quantitative discussion of the error related to this type of measurement. Analyzing the main error sources, we find that even tiny deviations of the shape from the perfect sphere may lead to substantial errors that dominate the overall error of the measurement. Therefore, we come to the conclusion that the well-established method to measure the coefficient of restitution through the emitted sound is applicable only for the case of nearly perfect spheres. For larger falling height, air drag may lead to considerable error, too.

},
author = {Heckel, Michael and Glielmo, Aldo and Gunkelmann, Nina and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.93.032901},
faupublication = {yes},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Can} we obtain the coefficient of restitution from the sound of a bouncing ball?},
url = {http://link.aps.org/doi/10.1103/PhysRevE.93.032901},
volume = {93},
year = {2016}
}
@inproceedings{faucris.116710044,
abstract = {The multisphere method is commonly used as an approximation for modeling particles of complex geometric shapes in DEM simulations. However, typically the mass and moment of inertia of the resulting sphere clumps are incorrectly computed as a result of the (artifactual) contribution of the sphere-sphere overlaps. We adapted the current public release of LIGGGHTS in order to perform DEM simulations of rigid bodies using the mass and moment of inertia of the particles as obtained through an analytical (exact) metho},
author = {Ribeiro Parteli, Eric Josef},
booktitle = {the 6th International Conference on Discrete Element Methods},
faupublication = {yes},
pages = {217 - 222},
peerreviewed = {unknown},
title = {{Using} {LIGGGHTS} for performing {DEM} simulations of particles of complex shapes with the multisphere method},
year = {2013}
}
@inproceedings{faucris.117368724,
author = {Engel, Michael},
booktitle = {European Conference on Advanced Materials},
date = {2007-09-10/2007-09-13},
faupublication = {no},
peerreviewed = {unknown},
title = {{Metadislocations} in {Al}-{Pd}-{Mn}-phases as examples for partial dislocations in {CMAs}},
venue = {Nürnberg},
year = {2007}
}
@article{faucris.122087284,
abstract = {We have discovered an invariant distribution for local packing configurations in static granular media. This distribution holds in experiments for packing fractions covering most of the range from random loose packed to random close packed, for bead packs prepared both in air and in water. Assuming only that there exist elementary cells in which the system volume is subdivided, we derive from statistical mechanics a distribution that is in accord with the observations. This universal distribution function for granular media is analogous to the Maxwell-Boltzmann distribution for molecular gasses.},
author = {Schröter, Matthias and Aste, T. and Di Matteo, Tiziana and Saadatfar, Mohammad and Senden, T.J. and Swinney, Harry L.},
doi = {10.1209/0295-5075/79/24003},
faupublication = {no},
journal = {EPL - Europhysics Letters},
month = {Jan},
peerreviewed = {Yes},
title = {{An} invariant distribution in static granular media},
volume = {79},
year = {2007}
}
@article{faucris.109109924,
abstract = {We study the organization of stability phases in the control parameter space of a periodically driven Brusselator. Specifically, we report high-resolution stability diagrams classifying periodic phases in terms of the number of spikes per period of their regular oscillations. Such diagrams contain accumulations of periodic oscillations with an apparently unbounded growth in the number of their spikes. In addition to the entrainment horns, we investigate the organization of oscillations in the limit of small frequencies and amplitudes of the drive. We find this limit to be free from chaotic oscillations and to display an extended and regular tiling of periodic phases. The Brusselator contains also several features discovered recently in more complex scenarios like, e.g. in lasers and in biochemical reactions, and exhibits properties which are helpful in the generic classification of entrainment in driven systems. Our stability diagrams reveal snippets of how the full classification of oscillations might look like for a wide class of flows.},
author = {Gallas, Jason},
doi = {10.1142/S0217984915300185},
faupublication = {yes},
journal = {Modern Physics Letters B},
peerreviewed = {Yes},
title = {{Periodic} oscillations of the forced {Brusselator}},
volume = {29},
year = {2015}
}
@article{faucris.122879504,
abstract = {Structural modifications in complex metallic epsilon-Al-Pd-(Mn, Fe) samples were studied by means of transmission electron microscopy. The modifications were observed in the vicinity of metadislocations and at phase boundaries. They are determined by the density and inclination of phason planes. In the vicinity of metadislocations and at an epsilon(6)-epsilon(28) phase boundary, new monoclinic E-type structures appear locally, which had not been detected as bulk phases in Al-Pd-(Mn, Fe) previously. The present work points out the close entanglement between defects, i.e. metadislocations and phason planes, and structural modifications in E-type complex metallic alloys. An extended classification of E-type phases including monoclinic phases is presented on the basis of two different tiling descriptions.},
author = {Engel, Michael and Trebin, Hans-Rainer and Heggen, Marc and Balanetskyy, Sergiy and Feuerbacher, Michael},
doi = {10.1080/14786430801894528},
faupublication = {no},
journal = {Philosophical Magazine},
pages = {507-521},
peerreviewed = {Yes},
title = {{Structural} variations in epsilon-type {Al}-{Pd}-({Mn}, {Fe}) complex metallic alloy phases},
volume = {88},
year = {2008}
}
@article{faucris.122800744,
abstract = {Packings of cohesive nanoparticles, that is nano powders, may be obtained as the result of repeated fragmentation–reagglomeration cycles (Schwager et al. in Phys Rev Lett 100:218002, 2008) such that the resulting sediment reveals a fractal structure. The size distribution of the fragments after a fragmentation step is a superposition of a narrow distribution of large particles (chunks) whose size is determined by the cutting length and a power-law distribution for small particles, representing scale invariant dust. It was shown that the exponent of the power-law, τ , is in non-trivial relation to the fractal dimension, d f , via d f (2 − τ ) = 1. This poses the question for the structure of the sediment created by repeated fragmentation–reagglomeration cycles when the dust particles are excluded from the reagglomeration step. We found that even in this case, repeated fragmentation-reagglomeration cycles yield a sediment of fractal structure with slightly reduced fractal dimension while the dust exponent, τ , remains unchanged.},
author = {Topic, Nikola and Wolf, Dietrich E. and Pöschel, Thorsten},
doi = {10.1007/s10035-015-0601-1},
faupublication = {yes},
journal = {Granular Matter},
peerreviewed = {Yes},
title = {{Fractal} {Substructure} of a nanopowder generated by repeated fragmentation and sedimentation: {The} role of the dust},
year = {2016}
}
@article{faucris.117058744,
abstract = {Icosahedral quasicrystals (IQCs) are a form of matter that is ordered but not periodic in any direction. All reported IQCs are intermetallic compounds and either of face-centred-icosahedral or primitive-icosahedral type, and the positions of their atoms have been resolved from diffraction data. However, unlike axially symmetric quasicrystals, IQCs have not been observed in non-atomic (that is, micellar or nanoparticle) systems, where real-space information would be directly available. Here, we show that an IQC can be assembled by means of molecular dynamics simulations from a one-component system of particles interacting via a tunable, isotropic pair potential extending only to the third-neighbour shell. The IQC is body-centred, self-assembles from a fluid phase, and in parameter space neighbours clathrates and other tetrahedrally bonded crystals. Our findings elucidate the structure and dynamics of the IQC, and suggest routes to search for it and design it in soft matter and nanoscale systems.},
author = {Engel, Michael and Damasceno, Pablo F. and Glotzer, Sharon C. and Philips, Carolyn L.},
doi = {10.1038/nmat4152},
faupublication = {no},
journal = {Nature Materials},
pages = {109-116},
peerreviewed = {unknown},
title = {{Computational} self-assembly of a one-component icosahedral quasicrystal},
volume = {14},
year = {2014}
}
@book{faucris.122766204,
abstract = {Computer simulations not only belong to the most important methods for the theoretical investigation of granular materials, but also provide the tools that have enabled much of the expanding research by physicists and engineers. The present book is intended to serve as an introduction to the application of numerical methods to systems of granular particles. Accordingly, emphasis is placed on a general understanding of the subject rather than on the presentation of the latest advances in numerical algorithms. Although a basic knowledge of C++ is needed for the understanding of the numerical methods and algorithms in the book, it avoids usage of elegant but complicated algorithms to remain accessible for those who prefer to use a different programming language. While the book focuses more on models than on the physics of granular material, many applications to real systems are presented. © Springer-Verlag Berlin Heidelberg 2005.},
author = {Pöschel, Thorsten and Schwager, Thomas},
doi = {10.1007/3-540-27720-X},
faupublication = {no},
isbn = {9783540214854},
pages = {1-322},
publisher = {Springer Berlin Heidelberg},
title = {{Computational} granular dynamics: {Models} and algorithms},
year = {2005}
}
@article{faucris.119660464,
abstract = {Instruments for surgical and dental application based on oscillatory mechanics submit unwanted vibrations to the operator's hand. Frequently the weight of the instrument's body is increased to dampen its vibration. Based on recent research regarding the optimization of granular damping we developed a prototype granular damper that attenuates the vibrations of an oscillatory saw twice as efficiently as a comparable solid mass. © 2012 Elsevier B.V. All rights reserved.},
author = {Heckel, Michael and Sack, Achim and Kollmer, Jonathan and Pöschel, Thorsten},
doi = {10.1016/j.physa.2012.04.007},
faupublication = {yes},
journal = {Physica A-Statistical Mechanics and Its Applications},
keywords = {Dissipation mechanism; Granular damper; Granular system; Vibrations},
pages = {4442-4447},
peerreviewed = {Yes},
title = {{Granular} dampers for the reduction of vibrations of an oscillatory saw},
volume = {391},
year = {2012}
}
@article{faucris.123449084,
abstract = {Soft particles are known to overlap and form stable clusters that self-assemble into periodic crystalline phases with density-independent lattice constants. We use molecular dynamics simulations in two dimensions to demonstrate that, through a judicious design of an isotropic pair potential, one can control the ordering of the clusters and generate a variety of phases, including decagonal and dodecagonal quasicrystals. Our results confirm analytical predictions based on a mean-field approximation, providing insight into the stabilization of quasicrystals in soft macromolecular systems, and suggesting a practical approach for their controlled self-assembly in laboratory realizations using synthesized soft-matter particles.},
author = {Engel, Michael and Barkan, Kobi and Lifshitz, Ron},
doi = {10.1103/PhysRevLett.113.098304},
faupublication = {no},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Controlled} {Self}-{Assembly} of {Periodic} and {Aperiodic} {Cluster} {Crystals}},
volume = {113},
year = {2014}
}
@article{faucris.117058964,
abstract = {Entropy drives the phase behavior of colloids ranging from dense suspensions of hard spheres or rods to dilute suspensions of hard spheres and depletants. Entropic ordering of anisotropic shapes into complex crystals, liquid crystals, and even quasicrystals was demonstrated recently in computer simulations and experiments. The ordering of shapes appears to arise from the emergence of directional entropic forces (DEFs) that align neighboring particles, but these forces have been neither rigorously defined nor quantified in generic systems. Here, we show quantitatively that shape drives the phase behavior of systems of anisotropic particles upon crowding through DEFs. We define DEFs in generic systems and compute them for several hard particle systems. We show they are on the order of a few times the thermal energy (k(B)T) at the onset of ordering, placing DEFs on par with traditional depletion, van der Waals, and other intrinsic interactions. In experimental systems with these other interactions, we provide direct quantitative evidence that entropic effects of shape also contribute to self-assembly. We use DEFs to draw a distinction between self-assembly and packing behavior. We show that the mechanism that generates directional entropic forces is the maximization of entropy by optimizing local particle packing. We show that this mechanism occurs in a wide class of systems and we treat, in a unified way, the entropy-driven phase behavior of arbitrary shapes, incorporating the well-known works of Kirkwood, Onsager, and Asakura and Oosawa.},
author = {Engel, Michael and van Anders, Greg and Klotsa, Daphne and Ahmed, N. Khalid and Glotzer, Sharon C.},
doi = {10.1073/pnas.1418159111},
faupublication = {no},
journal = {Proceedings of the National Academy of Sciences of the United States of America},
keywords = {entropy;self-assembly;colloids;nanoparticles;shape},
pages = {E4812-E4821},
peerreviewed = {Yes},
title = {{Understanding} shape entropy through local dense packing},
volume = {111},
year = {2014}
}
@article{faucris.114270464,
abstract = {In quasicrystals, the phason degree of freedom and the inherent anharmonic potentials lead to complex dynamics, which cannot be described by the usual phonon modes of motion. We have constructed simple one-dimensional model systems, the dynamic Fibonacci chain, and approximants thereof. They allow us to study the dynamics of periodic and quasiperiodic structures with anharmonic double-well interactions both by analytical calculations and by molecular-dynamics simulations. We found soliton modes such as breathers and kink solitons and we were able to obtain closed analytical solutions for special cases, which are in good agreement with our simulations. Calculation of the specific heat shows an increase above the Dulong-Petit value, which is due to the anharmonicity of the potential and not caused by the phason degree of freedom.},
author = {Engel, Michael and Lipp, Hansjörg and Trebin, Hans-Rainer and Sonntag, Steffen},
doi = {10.1103/PhysRevB.81.064302},
faupublication = {no},
journal = {Physical Review B},
peerreviewed = {Yes},
title = {{Phason} dynamics in one-dimensional lattices},
volume = {81},
year = {2010}
}
@article{faucris.109808424,
abstract = {We consider the transition of a horizontally vibrated monodisperse granular monolayer between its condensed state and its three-dimensional gaseous state as a function of the vibration parameters, amplitude, and frequency as well as particle number density. The transition is characterized by an abrupt change of the dynamical state which leaves its fingerprints in several measurable quantities including dissipation rate, sound emission, and a gap size which characterizes the sloshing motion of the material. The transition and its pronounced hysteresis is explained through the energy due to the collective motion of the particles relative to the container.},
author = {Heckel, Michael and Sack, Achim and Kollmer, Jonathan and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.91.062213},
faupublication = {yes},
journal = {Physical Review E - Statistical, Nonlinear, and Soft Matter Physics},
peerreviewed = {Yes},
title = {{Fluidization} of a horizontally driven granular monolayer},
volume = {91},
year = {2015}
}
@article{faucris.121151624,
abstract = {We investigate the average turbulent wind field over a barchan dune by means of Computational Fluid Dynamics. We find that the fractional speed-up ratio of the wind velocity over the three-dimensional barchan shape differs from the one obtained from two-dimensional calculations of the airflow over the longitudinal cut along the dune's symmetry axis - that is, over the equivalent transverse dune of same size. This finding suggests that the modeling of the airflow over the central slice of barchan dunes is insufficient for the purpose of the quantitative description of barchan dune dynamics as three-dimensional flow effects cannot be neglected.},
author = {Michelsen, Britt and Strobl, Severin and Ribeiro Parteli, Eric Josef and Pöschel, Thorsten},
doi = {10.1038/srep16572},
faupublication = {yes},
journal = {Scientific Reports},
peerreviewed = {Yes},
title = {{Two}-dimensional airflow modeling underpredicts the wind velocity over dunes},
volume = {5},
year = {2015}
}
@article{faucris.109942184,
abstract = {We propose a new method for the calculation of the statistical properties, e.g., the entropy, of unknown generators of symbolic sequences. The probability distribution p(k) of the elements k of a population can be approximated by the frequencies f(k) of a sample provided the sample is long enough so that each element k occurs many times. Our method yields an approximation if this precondition does not hold. For a given f(k) we recalculate the Zipf-ordered probability distribution by optimization of the parameters of a guessed distribution. We demonstrate that our method yields reliable results. © 1995 Plenum Publishing Corporation.},
author = {Pöschel, Thorsten and Ebeling, Werner and Rose, Helge},
doi = {10.1007/BF02179880},
faupublication = {no},
journal = {Journal of Statistical Physics},
keywords = {Entropy estimation; information science},
pages = {1443-1452},
peerreviewed = {Yes},
title = {{Guessing} probability distributions from small samples},
volume = {80},
year = {1995}
}
@article{faucris.122864764,
abstract = {Figure Persented: Polyhedra and their arrangements have intrigued humankind since the ancient Greeks and are today important motifs in condensed matter, with application to many classes of liquids and solids. Yet, little is known about the thermodynamically stable phases of polyhedrally shaped building blocks, such as faceted nanoparticles and colloids. Although hard particles are known to organize due to entropy alone, and some unusual phases are reported in the literature, the role of entropic forces in connection with polyhedral shape is not well understood. Here, we study thermodynamic self-assembly of a family of truncated tetrahedra and report several atomic crystal isostructures, including diamond, β-tin, and high-pressure lithium, as the polyhedron shape varies from tetrahedral to octahedral. We compare our findings with the densest packings of the truncated tetrahedron family obtained by numerical compression and report a new space-filling polyhedron, which has been overlooked in previous searches. Interestingly, the self-assembled structures differ from the densest packings. We show that the self-assembled crystal structures can be understood as a tendency for polyhedra to maximize face-to-face alignment, which can be generalized as directional entropic forces. © 2011 American Chemical Society.},
author = {Engel, Michael and Damasceno, Pablo F. and Glotzer, Sharon C.},
doi = {10.1021/nn204012y},
faupublication = {no},
journal = {Acs Nano},
keywords = {computer simulation; directional entropy; nanoparticles; polyhedra packing; self-assembly; space-filling},
pages = {609-614},
peerreviewed = {Yes},
title = {{Crystalline} assemblies and densest packings of a family of truncated tetrahedra and the role of directional entropic forces},
volume = {6},
year = {2012}
}
@article{faucris.109976064,
abstract = {This paper shows that negative coefficients of normal restitution occur inevitably when the interaction force between colliding particles is finite. We derive an explicit criterion showing that for any set of material properties there is always a collision geometry leading to negative restitution coefficients. While from a phenomenological point of view, negative coefficients of normal restitution appear rather artificial, this phenomenon is generic and implies an important overlooked limitation of the widely used hard sphere model. The criterion is explicitly applied to two paradigmatic situations: for the linear dashpot model and for viscoelastic particles. In addition, we show that for frictional particles the phenomenon is less pronounced than for smooth spheres. © 2012 American Physical Society.},
author = {Müller, Patric and Krengel, Dominik and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.85.041306},
faupublication = {yes},
journal = {Physical Review E},
peerreviewed = {Yes},
title = {{Negative} coefficient of normal restitution},
volume = {85},
year = {2012}
}
@article{faucris.107033124,
abstract = {
Grid based fluid simulation methods are not able to solve complex non-linear dynamics like the rupture of a dynamic liquid bridge between freely colliding solids–an exemplary scenario of capillary forces competing with inertial forces in engineering applications–using a monolithic formulation for the solid and liquid phases present. We introduce a new Incompressible Smoothed Particle Hydrodynamics method for simulating three dimensional fluid-solid interaction flows with capillary (wetting and surface tension) effects at free surfaces. This meshless approach presents significant advantages over grid based approaches in terms of being monolithic and in handling interaction with free solids. The method is validated for accuracy and stability in dynamic scenarios involving surface tension and wetting. We then present three dimensional simulations of crown forming instability following the splash of a liquid drop, and the rupture of a liquid bridge between two colliding solid spheres, to show the method’s advantages in the study of dynamic micromechanical phenomena involving capillary flows.

},
author = {Nair, Prapanch and Pöschel, Thorsten},
doi = {10.1016/j.ces.2017.10.042},
faupublication = {yes},
journal = {Chemical Engineering Science},
pages = {192-204},
peerreviewed = {Yes},
title = {{Dynamic} capillary phenomena using {Incompressible} {SPH}},
volume = {176},
year = {2017}
}
@article{faucris.119532644,
abstract = {Predicting structure from the attributes of a material's building blocks remains a challenge and central goal for materials science. Isolating the role of building block shape for self-assembly provides insight into the ordering of molecules and the crystallization of colloids, nanoparticles, proteins, and viruses. We investigated 145 convex polyhedra whose assembly arises solely from their anisotropic shape. Our results demonstrate a remarkably high propensity for thermodynamic self-assembly and structural diversity. We show that from simple measures of particle shape and local order in the fluid, the assembly of a given shape into a liquid crystal, plastic crystal, or crystal can be predicted.},
author = {Engel, Michael and Damasceno, Pablo F. and Glotzer, Sharon C.},
doi = {10.1126/science.1220869},
faupublication = {no},
journal = {Science},
pages = {453-457},
peerreviewed = {Yes},
title = {{Predictive} {Self}-{Assembly} of {Polyhedra} into {Complex} {Structures}},
volume = {337},
year = {2012}
}
@article{faucris.109900384,
abstract = {The detailed mechanism of the formation of net and branching leaf structures is not known yet. Several mathematical modelling attempts to generate those structures have been made previously, based on biochemical or purely mathematical assumptions. Here, we present a simple model, based on plausible biophysical suppositions, which is able to reproduce the formation of a ramified structure grown out of a single activated cell. © 1994.},
author = {Pöschel, Thorsten and Malchow, H.},
doi = {10.1016/0960-0779(94)90004-3},
faupublication = {no},
journal = {Chaos Solitons & Fractals},
pages = {1883-1888},
peerreviewed = {Yes},
title = {{A} simple model for the growth of ramified leaf structures},
volume = {4},
year = {1994}
}
@article{faucris.107384684,
abstract = {
Stochastic Rotation Dynamics (SRD) is a valuable numerical tool extensively used in many domains of hydrodynamics simulations including colloidal suspensions. We investigate the dynamics of two colloidal particles in the regime of low Reynolds number by means of SRD in 3D. In contrast to well-known analytical and experimental results, no long-range interaction between the suspended particles could be found, independent of the size of the particles and the Mach and Péclet numbers. We attribute this behavior to the compressible nature and low sound velocity in the SRD solvent. The inability of representing long-range interactions poses an important limitation to the applicability of SRD to certain physical systems. We provide an estimation of typical length scales for which SRD can be applied.

},
author = {Shakeri, Ali and Lee, Kuang-Wu and Pöschel, Thorsten},
doi = {10.1063/1.5008812},
faupublication = {yes},
journal = {Physics of Fluids},
month = {Jan},
peerreviewed = {unknown},
title = {{Limitation} of stochastic rotation dynamics to represent hydrodynamic interaction between colloidal particles},
volume = {30},
year = {2018}
}
@article{faucris.110045584,
abstract = {A force-free granular gas was considered with an impact-velocity-dependent coefficient of restitution as it followed from the model of viscoelastic particles. Structural formation in this system was studied by means of three independent methods: event-driven molecular dynamics (MD), numerical solution of the hydrodynamic (HD) equations, and linear stability analysis of the HD equations. It was observed that cluster growth resulted in the decrease in gas density with time. It was found that structural formulation occurred in force-free granular gases only as a transient process.},
author = {Brilliantov, Nikolai V. and Salueña, Clara and Schwager, Thomas and Pöschel, Thorsten},
doi = {10.1103/PhysRevLett.93.134301},
faupublication = {no},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Transient} structures in a granular gas},
volume = {93},
year = {2004}
}
@article{faucris.122098284,
abstract = {We prepare packings of frictional tetrahedra with volume fractions phi ranging from 0.469 to 0.622 using three different experimental protocols under isobaric conditions. Analysis via x-ray microtomography reveals that the contact number Z grows with phi, but does depend on the preparation protocol. While there exist four different types of contacts in tetrahedra packings, our analysis shows that the edge-to-face contacts contribute about 50% of the total increase in Z. The number of constraints per particle C increases also with phi and even the loosest packings are strongly hyperstatic, i.e., mechanically over-determined with C approximately twice the degrees of freedom each particle possesses.},
author = {Schröter, Matthias and Neudecker, Max and Ulrich, Stephan and Herminghaus, Stephan},
doi = {10.1103/PhysRevLett.111.028001},
faupublication = {no},
journal = {Physical Review Letters},
peerreviewed = {Yes},
title = {{Jammed} {Frictional} {Tetrahedra} are {Hyperstatic}},
volume = {111},
year = {2013}
}
@article{faucris.110013464,
abstract = {The coefficient of self-diffusion for a homogeneously cooling granular gas changes significantly if the impact-velocity dependence of the restitution coefficient ε is taken into account. For the case of a constant ε the particles spread logarithmically slowly with time, whereas a velocity-dependent coefficient yields a power law time dependence. The impact of the difference in these time dependences on the properties of a freely cooling granular gas is discussed.},
author = {Brilliantov, Nikolai and Pöschel, Thorsten},
doi = {10.1103/PhysRevE.61.1716},
faupublication = {no},
journal = {Physical Review E},
pages = {1716-1721},
peerreviewed = {Yes},
title = {{Self}-diffusion in granular gases},
volume = {61},
year = {2000}
}
@article{faucris.213049122,
abstract = {Photoelastic techniques are used to make both qualitative and quantitative measurements of the forces within idealized granular materials. The method is based on placing a birefringent granular material between a pair of polarizing filters, so that each region of the material rotates the polarization of light according to the amount of local of stress. In this review paper, we summarize past work using the technique, describe the optics underlying the technique, and illustrate how it can be used to quantitatively determine the vector contact forces between particles in a 2D granular system. We provide a description of software resources available to perform this task, as well as key techniques and resources for building an experimental apparatus.},
author = {Daniels, Karen E. and Kollmer, Jonathan and Puckett, James G.},
doi = {10.1063/1.4983049},
faupublication = {no},
journal = {Review of Scientific Instruments},
note = {EAM Import::2019-03-12},
peerreviewed = {Yes},
title = {{Photoelastic} force measurements in granular materials},
volume = {88},
year = {2017}
}
@article{faucris.114389704,
abstract = {Investigating how tightly objects pack space is a long-standing problem, with relevance for many disciplines from discrete mathematics to the theory of glasses. Here we report on the fundamental yet so far overlooked geometric property that disordered mono-disperse spherical bead packs have significant local structural anisotropy manifest in the shape of the free space associated with each bead. Jammed disordered packings from several types of experiments and simulations reveal very similar values of the cell anisotropy, showing a linear decrease with packing fraction. Strong deviations from this trend are observed for unjammed configurations and for partially crystalline packings above 64%. These findings suggest an inherent geometrical reason why, in disordered packings, anisotropic shapes can fill space more efficiently than spheres, and have implications for packing effects in non-spherical liquid crystals, foams and structural glasses.},
author = {Schröder-Turk, Gerd and Mickel, Walter and Schröter, Matthias and Delaney, Gary and Saadatfar, Mohammad and Senden, T.J. and Mecke, Klaus and Aste, T.},
doi = {10.1209/0295-5075/90/34001},
faupublication = {yes},
journal = {EPL - Europhysics Letters},
pages = {34001},
peerreviewed = {Yes},
title = {{Disordered} spherical bead packs are anisotropic},
volume = {90},
year = {2010}
}
@article{faucris.109922604,
abstract = {We investigate collective dissipative properties of vibrated granular materials by means of molecular-dynamics simulations. Rates of energy losses indicate three different regimes or "phases" in the amplitude-frequency plane of the external forcing, namely solid, convective, and gaslike regimes. The behavior of effective damping decrement in the solid regime is glassy. Practical applications are discussed. ©1999 The American Physical Society.},
author = {Salueña, Clara and Pöschel, Thorsten and Esipov, Sergei E.},
doi = {10.1103/PhysRevE.59.4422},
faupublication = {no},
journal = {Physical Review E},
pages = {4422-4425},
peerreviewed = {Yes},
title = {{Dissipative} properties of vibrated granular materials},
volume = {59},
year = {1999}
}