Excess properties of almost ideal many-particle binary mixtures have been studied theoretically in the framework of the Kirkwood-Buff approach based on the calculation of statistical correlation integrals. With the help of the Percus-Yevick approximation for distribution functions and the superposition approximation for partial structure factors, an expression describing the compressibility of binary system in terms of the parameters of monodisperse phases i s derived. Using generalized functions, analytical expressions for correlation integrals in terms of component packing fractions are obtained. The theoretical results for the compressibility of a system are compared with the experimental data on the sound velocity. In this case, we introduce a correction function, which depends on the packing degree and the composition content and is determined by fitting the experimental data. This allows us to describe the excess properties of binary systems. K e y w o r d s: Kirkwood-Buff method, binary mixture, excess properties, isothermal compressibility.

No abstract

No abstract

Abstract. We report physical phenomena occurring in a vertical Newton's cradle system. A dozen of metallic spheres are placed in a vertical tube. Therefore, the gravity induces a non-uniform pre-compression of the beads and a restoring force. An electromagnetic hammer hits the bottom bead at frequencies tuned between 1 and 14 Hz. The motion of the beads are recorded using a high-speed camera. For low frequencies, the pulses travel through the pile and expel a few beads from the surface. Then, after a few bounces of these beads, the system relaxes to the chain of contacting grains. When the frequency is increased, the number of fluidized beads increases. In the fluidized part of the pile, adjacent beads are bouncing in opposition of phase. This phase locking of the top beads is observed even when the bottom beads experience chaotic motions. While the mechanical energy increases monotically with the bead vertical position, heterogeneous patterns in the kinetic energy distribution are found when the system becomes fluidized.

We have obtained rigorous analytic and numerical solutions of the equations which govern the transport of mechanical perturbations in a gently precompressed 1D Hertz chain. Both finite-length and infinite-length systems have been studied. We examine both discrete and continuousformulations of the mentioned problem. A few families of analytic solutions of the problem given in the form of quasinormal waves and specific resonance modes have been obtained in the linear approximation for weakly perturbed inhomogeneous systems. Resonance modes are proposed to be interpreted as the Ramsauer–Townsend effect which happens due to the inhomogeneity. The obtained analytic results have been compared with numerical solutions of the discrete equations. We observe a multiscaled scenario of the impulse transport in an inhomogeneous force chain which could happens either asymptotically or at the intermittency between discrete- and continuous limits of the formulated problem. The role of a disorder has been also analyzed with the help of the Dyson concept.