The existence and stability of “orbitally uniform” rotations of a vibrating dumbbell on an elliptic orbit

The problem of planar motions of a variable-length dumbbell-shaped body in the central field of the Newton attraction is considered. The rules of varying the dumbbell length, at which the dumbbell with respect to the true anomaly can rotate uniformly around the center of mass, are indicated for the equation of motion of the dumbbell written in a satellite approximation [1–8]. When fulfilling these rules, the necessary stability conditions of mentioned motions are investigated.     

Simulation of a functional solution to the acoustic tomography problem for data from quasi-point transducers

Two variants of a functional-analytical algorithm intended for solving inverse tomography problems are discussed and numerically carried out. The acoustic fields that are transmitted and received by transducers, which are equivalent to point ones, serve as experimental data. These data are used to calculate the classical or generalized scattering amplitude, and the scatterer characteristics are then reconstructed. The algorithm requires neither model linearization, no iterations for refining the estimates of scatterers, thus making it attractive for solving acoustic-tomography problems in different applications. The results of the numerical reconstruction of inhomogeneities in the sound velocity and absorption in a medium are presented.     

Molecular dynamic simulation of micellar solutions: A coarse-grain model

Molecular dynamic simulation of surfactant solutions is performed using a coarse-grain model. Aqueous butyl-, octyl-, dodecyl-, and hexadecyltrimethylammonium chloride solutions are investigated. The polydispersity of micellar solutions and micelle structure are studied, and the degree of counterion binding is estimated. It is shown that, when studying solutions of ionic surfactants, it is necessary to correctly account for electrostatic interactions.     

A spatial correlation method for reconstructing blood flow velocity vector in the nonlinear tomography

A method for reconstructing the total blood flow velocity vector distribution is proposed. Experimental data are obtained with the help of the second-order nonlinearity parameter tomography scheme that employs wideband coded signals and a small number of transducers. The data are processed using the selective matched filtering technique in combination with spatial correlation of fragments of the speckle structure that appears in the process of reconstruction of the spatial nonlinearity parameter distribution. Results of numerical simulations are presented.     

Numerical and physical modeling of the tomography process based on third-order nonlinear acoustic effects

The possibility of employing the nonlinear effect of generation of third-order combination waves for the purposes of medical diagnostics is analyzed. This effect can be used to reconstruct the spatial distribution of acoustic nonlinear parameters in the framework of the wave approach. Contributions of third-order nonlinear scattering itself and of the double second-order scattering are evaluated. These two competing processes evolve simultaneously and produce similar observed effects, which can nevertheless be separated. A two-dimensional experimental scheme that contains only three transmitters and one receiver, uses two primary wideband modulated waves and an introduced third monochromatic wave, is proposed. Results of the numerical and physical model experiments are provided.