Theoretical Study of Nonradiative Energy Transfer from Exciplex to Perovskites

Russian Physics Journal - The results of theoretical studies of energy transfer from the exciplex of TCTA and Bphen molecules to CaZrO3, SrZrO3, and BaZrO3 perovskites are presented. As a result,...     

Convection of a stratified colloidal suspension

The convection of a colloidal suspension, which is a binary mixture of a carrier medium with an admixture of nanoparticles having a large positive thermal diffusion parameter, has been studied for the case of the heating of a horizontal cell from below and periodic conditions at the vertical boundaries corresponding to the experimental situation of ring channels. Bifurcation diagrams have been constructed for vibrational and monotonic regimes of the convection of the colloidal mixture. The time dependences of the maximum stream function and the stream function at a fixed point of the cell, as well as the spatial distributions of the concentration field of the colloid admixture, have been obtained. It has been shown that a stable regime of traveling waves exists in a certain region of the parameters of the problem (Boltzmann and Rayleigh numbers characterizing the gravitational stratification and intensity of the thermal effect, respectively).     

Localized Plastic Deformation of Metal-Intermetallic Laminated Composites after Equal Channel Angular Pressing

Russian Physics Journal - The paper presents mathematical simulation of localized plastic deformation of metal-intermetallic laminated composites after equal channel angular pressing. Deformation...     

Quantum model of the magnetic dynamics of single-domain particles for describing their magnetization curves and Mössbauer spectra in a weak magnetic field

A universal approach to describing the equilibrium magnetization curves and relaxation Mössbauer spectra of magnetic nanoparticles is proposed for consistent analysis of magnetometry and gamma-resonance experimental data, based solving a quantum-mechanical problem for a particle with spin S that has intrinsic magnetic anisotropy and is positioned in an external magnetic field.     

Equistrong heavy beam: Solving the problem of Galileo Galilei

In his main book “Discorsie Dimostrazioni Matematiche, Intorno a Due Nuove Scienze” published in 1638 by Elsevier in Leiden, Galileo Galilei, “the Father” of modern science, put the material science and strength of materials on the first place. He introduced the notions of stress and strength that have been fundamental since then. Moreover, in unison with Plato’s theory of forms he found out the perfect shape of a force-bent beam we call today equistrong. This discovery laid the foundation for search of other perfect elastic bodies as a continuation of Galilei’s work. There are no theorems of existence for equistrong bodies so that the quest for them is like a gold-digging. In what follows, the shapes of the following heavy, equistrong beams were found out: a) beam of constant thickness and of variable width, simply supported at both ends, b) beam clamped at one end and loaded at the other end while having either constant thickness and variable width, or constant width and variable thickness, and c) equistrong shape of the profile of aircraft wings accounting for gravity and lift loads. The shape of equistrong rod at buckling under a compressive force is found in the Euler’s problem. Equistrong structures possess minimum weight for given safety factor or maximum safety factor for given weight.     

Theory of one-dimensional unsteady transport of heavy particles by a flow of fluid

A study is made of the one-dimensional unsteady transport of heavy particles of rock by a flow of flushing fluid in a bore hole. The proposed theory of this process leads to a quasilinear Monge—Ampere equation of parabolic type. A well-posed boundary-value problem is formulated and a method indicated for its solution. A typical problem is solved, and this illustrates the qualitative picture of the physical process. The investigated process of flushing the end of a bore hole is the main process that limits the drilling rate in a superdeep bore hole.Translated from Izvestiya Akademii Nauk SSSR, Mekhanika Zhidkosti i Gaza, No. 2, pp. 73–79, March–April, 1984.