Pulse Dynamics in a Chain of Granules With Friction

We study the dynamics of a pulse in a chain of granules with friction. We present theories for chains of cylindrical granules (Hertz potential with exponent $n=2$) and of granules with other geometries ($n>2$). Our results are supported via numerical simulations for cylindrical and for spherical granules ($n=5/2$).Comment: Submitted to PR

Kinetics and Jamming Coverage in a Random Sequential Adsorption of Polymer Chains

Using a highly efficient Monte Carlo algorithm, we are able to study the growth of coverage in a random sequential adsorption (RSA) of self-avoiding walk (SAW) chains for up to 10^{12} time steps on a square lattice. For the first time, the true jamming coverage (theta_J) is found to decay with the chain length (N) with a power-law theta_J propto N^{-0.1}. The growth of the coverage to its jamming limit can be described by a power-law, theta(t) approx theta_J -c/t^y with an effective exponent y which depends on the chain length, i.e., y = 0.50 for N=4 to y = 0.07 for N=30 with y -> 0 in the asymptotic limit N -> infinity.Comment: RevTeX, 5 pages inclduing figure

Solitary wave trains in granular chains: Experiments, theory and simulations

The features of solitary waves observed in horizontal monodisperse chain of barely touching beads not only depend on geometrical and material properties of the beads but also on the initial perturbation provided at the edge of the chain. An impact of a large striker on a monodisperse chain, and similarly a sharp decrease of bead radius in a stepped chain, generates a solitary wave train containing many single solitary waves ordered by decreasing amplitudes. We find, by simple analytical arguments, that the unloading of compression force at the chain edge has a nearly exponential decrease. The characteristic time is mainly a function involving the grains' masses and the striker mass. Numerical calculations and experiments corroborate these findings.Comment: The original publication is available at http://www.springerlink.com (related papers at http://www.supmeca.fr/perso/jobs

Simulation of the growth of a binary composite by a controlled thermal annealing

The Metropolis algorithm is used to study the evolution of the density profile of particle species in a model binary composite material on a simple cubic lattice. A specified fraction of the lattice sites are occupied by particles of type A and the remaining sites are occupied by particles of type B. The Hamiltonian for the system includes both nearestneighbor particle-particle interactions and the interaction of the particle with a gravitational field. Particle-particle interaction strength, gravity, and the temperature govern the hopping of each particle in our annealing process. Variation of the planar density of the system by particle type is studied as a function of annealing time, temperature, and the volume fraction of the two components. We observe a variety of density distributions such as a linear density gradient with the thickness, staircase like variation in mass distribution, and their combinations over the length scales which depend on these parameters. The simulations show that a graded material with a desired density distribution can be designed by appropriately controlling the annealing period, temperature, and the volume fraction

A Real-Time 3D Reconstruction System for Screening Icosahedral Particles Under Different Conditions at the Microscope

Extended abstract of a paper presented at Microscopy and Microanalysis 2013 in Indianapolis, Indiana, USA, August 4 – August 8, 2013