Amstrup Wall (washgemini81)

To establish experimental signatures of this transition, we study the response function, and the correlation function of position u, velocity u[over ̇], and forces F under slow driving with velocity v>0. While at v=0 force or position correlations have a cusp at the origin and then decay at least exponentially fast to zero, this cusp is rounded at a finite driving velocity. We give a detailed analytic analysis for this rounding by velocity, which allows us, given experimental data, to extract the timescale of the response function, and to reconstruct the force-force correlator at v=0. The latter is the central object of the field theory, and as such contains detailed information about the universality class in question. We test our predictions by careful numerical simulations extending over up to ten orders in magnitude.We investigate the impact of composite objects. They consist of a soft layer on top of a rigid part with a hemispherical impacting end. The coefficient of restitution (e) of such objects is studied systematically as a function of the mass ratio and of the nature of the materials. For rather elastic materials, the coefficient of restitution is a nonmonotonic function of the mass ratio and exhibits important variations. The dynamics of the impact can be characterized by several bounces depending on the ratios between the four timescales at play. These include the duration of contact of the rigid part with the substrate and the time for the elastic waves to travel back and forth in the soft layer. In that sense, describing these projectiles requires one to take into account both the Hertzian theory of contact and the elastic waves described by Saint-Venant's approach.We study the response to shear deformations of packings of long spherocylindrical particles that interact via frictional forces with friction coefficient μ. TDI-011536 purchase The packings are produced and deformed with the help of molecular dynamics simulations combined with minimization techniques performed on a GPU. We calculate the linear shear modulus g_∞, which is orders of magnitude larger than the modulus g_0 in the corresponding frictionless system. The motion of the particles responsible for these large frictional forces is governed by and increases with the length ℓ of the spherocylinders. One consequence of this motion is that the shear modulus g_∞ approaches a finite value in the limit ℓ→∞, even though the density of the packings vanishes, ρ∝ℓ^-2. By way of contrast, the frictionless modulus decreases to zero, g_0∼ℓ^-2, in accordance with the behavior of density. Increasing the strain beyond a value γ_c∼μ, the packing strain weakens from the large frictional to the smaller frictionless modulus when contacts saturate at the Coulomb inequality and start to slide. In this regime, sliding friction contributes a "yield stress" σ_y=g_∞γ_c and the stress behaves as σ=σ_y+g_0γ. The interplay between static and sliding friction gives rise to hysteresis in oscillatory shear simulations.An optimal finite-time process drives a given initial distribution to a given final one in a given time at the lowest cost as quantified by total entropy production. We prove that for a system with discrete states this optimal process involves nonconservative driving, i.e., a genuine driving affinity, in contrast to the case of a system with continuous states. In a multicyclic network, the optimal driving affinity is bounded by the number of states within each cycle. If the driving affects forward and backwards rates nonsymmetrically, the bound additionally depends on a structural parameter characterizing this asymmetry.A computer simulation technique has been applied to the modeling of radiation redistribution functions in low- and moderate-density magnetized hydrogen plasmas. The radiating dipole is described within the Heisenberg picture, and perturbations by the plasma microfield are accounted for through a time-dependent Stark effect term in the Hamilton