Experimental-theoretical studies of the stability of orthotropic shells with a filler in axial compression

Conclusions 1. An analysis has been made of the solution to the problem of the stability of multilayer cylindrical shells having a filler and simple calculation formulas have been obtained for determining the critical forces.2. The stability of fiberglass-plastic shells with rubber-like fillers has been studied experimentally.3. Comparative experimental-theoretical studies of critical forces have been made, and the stability coefficients have been ascertained for the shell class under consideration.Translated from Mekhanika Polimerov, No. 3, pp. 485–489, May–June, 1978.     

Effect of the kapitza temperature jump on thermal phenomena in nanofluids

A dimensionless criterion characterizing the effect of the Kapitza temperature jump has been obtained to describe thermal processes in nanofluids.     

Laminar-turbulent transition in Hagen–Poiseuille flow of a real gas

The effect of gas non-ideality on the laminar-turbulent transition is studied experimentally as the flow in a long circular tube at room temperature. The gases SF₆ and Ar, differing significantly in the value of the second virial coefficient, were chosen for this study. Experiments were carried out by varying the pressure at the tube inlet (the maximum pressure of 10⁵ Pa) and at the tube outlet up to the chock flow (formation of a supersonic flow at the outlet). The difference between the critical Reynolds numbers in the flow of SF₆ and Ar was found. The largest difference was observed for the maximum pressures; with a decrease in pressure, the critical Reynolds numbers become closer. The conclusion is an effect of the non-ideal character of gas exists on the laminar-turbulent transition in Hagen–Poiseuille flow. Some experiments were suggested to confirm this conclusion.     

Interaction between glow discharge plasma and dust particles

The effect of dust particle concentration on gas discharge plasma parameters was studied through development of a self-consistent kinetic model which is based on solving the Boltzmann equation for the electron distribution function. It was shown that an increase in the Havnes parameter causes an increase in the average electric field and ion density, as well as a decrease in the charge of dust particles and electron density in a dust particle cloud. Self-consistent simulations for a wide range of plasma and dust particle parameters produced several scaling laws: these are laws for dust particle potential and electric field as a function of dust particle concentration and radius, and the discharge current density. The simulation results demonstrate that the process of self-consistent accommodation of parameters of dust particles and plasma in condition of particle concentration growth causes a growth in the number of high-energy electrons in plasma, but not to depletion of electron distribution function.     

Conditional extrema of functionals in topological linear spaces

A theorem of Lyusternik on conditional extrema of a differentiable functional defined on a Banach space is generalized to the case of a topological linear space.Translated from Matematicheskie Zametki, Vol. 14, No. 3, pp. 375–382, Septembers 1973.     

Axial-radial acoustic eigenoscillations near a thin-walled obstacle in a cylindrical channel with stepped narrowings

The dependencies are investigated of eigenfrequencies and eigenfunctions of acoustic axial-radial oscillations near a thin-walled obstacle in a channel with stepped narrowings on the geometric parameters of the oscillation region. It is discovered that, near the thin-walled cylindrical obstacles in an inhomogeneous cylindrical channel with the stepped two-sided cylindrical narrowing, the number of eigenfrequencies of the acoustic axial-radial oscillations of a gas may increase. The dependencies are obtained of eigenfrequencies on the geometric parameters of obstacles and the inhomogeneities of the channel.