Spectrum of one-dimensional oscillations in the combined stratified medium consisting of a viscoelasticmaterial and a viscous compressible fluid

Two averaged (effective) models corresponding to transverse and longitudinal oscillations in a periodic combined stratified medium are constructed. The medium considered consists of alternating layers of an isotropic viscoelastic material and a viscous compressible fluid. The dependence of the qualitative characteristics of the spectra of the averaged models on the linear dimensions of the stratified medium specimen is investigated.     

The spectrum of natural vibrations in a medium composed of layers of elastic material and viscous fluid

In this study, we investigated the spectral properties of two homogenized models corresponding to transverse and longitudinal vibrations in a microinhomogeneous layered combined medium. It is established that investigation of the spectrum of each model is reduced to finding the roots of the corresponding cubic equations, and the qualitative difference between the spectra of these models is also revealed.     

Exact bounded boundary controllability of vibrations of a two-dimensional membrane

The boundary control of vibrations of a plane membrane is considered. A constraint is imposed on the absolute value of the control function. The goal of the control is to drive the membrane to rest. The proof technique used in this paper can be applied to a membrane of any dimension, but the two-dimensional case is considered for simplicity and illustrative purposes.     

Some problems in acoustics of emulsions

The authors study small vibrations of a mixture (emulsion) of two weakly viscous compressible fluids, construct a macroscopic (homogenized) model of emulsion, and establish convergence (with respect to a small parameter) of solutions of the original boundary value problem for a two-phase fluid to solutions of the corresponding homogenized problem. The paper also describes the results of qualitative analysis of the spectrum of the macroscopic acoustic equation (the dynamical Darcy’s law), as well as typical spectral pictures obtained by numerical experiments.     

Thermodynamic characteristics of the radical cation of pyridine N-oxide and its reaction with methanol

The thermodynamic characteristics of the pyridine N-oxide radical cation were obtained and the energetics of its hydration were estimated. The electrochemically generated pyridine N-oxide radical cations are capable of cleaving an H atom from methanol, which is a component of the medium.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2438–2441, November, 1989.We would like to express our deep appreciation to A. E. Shilov for his cooperation in the research and discussion of the results of the study.     

Sensitivity of radioisotope methods of analysis

New radioanalytical methods of high sensitivity are surveyed. The sensitivity of a number of radioisotope methods of analysis is compared and theoretical sensitivity limits are discussed.     

Effect of Radio-Frequency and Ionizing Radiation on the ATmega8515 Microcontroller

Technical Physics - Effect of ultrabroadband radiation and bremsstrahlung on a complicated device (ATmega8515) placed in a radio-transparent housing is studied. Similar results are obtained in the...     

Molecular dynamics simulation of thermomechanical properties of montmorillonite crystal. 1. Isolated clay nanoplate

The structure and mechanical properties of clay nanoparticles is a subject of growing interest because of their numerous applications in engineering. We present the results of molecular dynamics simulation for a single nanoplate of pyrophyllite - a 2:1 clay mineral consisting of two tetrahedral sheets of SiO4 and an intervening octahedral AlO6 sheet. Simulations were performed in the temperature interval from 5 to 750 K using the ionic-type potentials of Cygan et al. On this basis the temperature dependences of structural parameters, characterizing both tetrahedral and octahedral sheets as well as single lamella, have been studied. Two slightly different structures were observed in this wide temperature interval. The mechanical properties of the nanoplate were calculated from stress-strain diagrams, which have been obtained at relatively slow rates of deformation (for molecular simulations). Using different types of loading, we calculated the full elasticity tensor and estimated the influence of temperature on its components. We estimated also the bending and torsion stiffnesses of the nanoplate as specific characteristics of this type of particle. Because the nanoplate is atomically thin, a reasonable determination of the thickness is a nontrivial problem, both in the modeling of mechanical properties and in physical interpretation of the obtained data. We propose a procedure for its calculation.     

Homogenization of the acoustic equations for a porous long-memory viscoelastic material filled with a viscous fluid

We consider the system of linear differential and integro-differential equations describing small vibrations in an ?-periodic combined medium consisting of a porous long-memory viscoelastic material and a viscous fluid filling the pores. By using the two-scale convergence method, we construct the system of homogenized equations and prove the convergence of solutions of the original problems to the solution of the homogenized problem as ? ?? 0.