Vol 62, No 9 (2017)

The acousto-optic figure of merit M₂ of the InI single crystal has been measured using the Dixon method at a laser-radiation wavelength of 1.15 μm. The maximum measured value was M₂ = 1100 × 10^–15 s³/kg. It is comparable with the figures of merit of the most efficient acousto-optic materials: TeO₂ and KRS-5. The velocities of longitudinal ultrasonic waves along the basic directions of the InI single crystal have also been measured.

The methods of laser processing and mechanical scribing are used for improving the functional characteristics of transformer magnetic cores from anisotropic Fe–3%Si alloys. The effect is achieved due to controlling the micromagnetic state of elements of the magnetic core by optimizing the type, the dimensional characteristics of their domains, and the magnetic-anisotropy type. These results lead to a substantial decrease in magnetic losses by 9–12% and, with subsequent thermal or thermomagnetic processing, by 14–16% due to decreasing the vortex-current component of magnetic losses.

The mechanisms for the sintering of ultrafine-grained 95%W–3.5%Ni–1.5%Fe heavy tungsten alloy powders have been investigated. It has been established that a decrease in the activation energy of grain boundary diffusion and the formation of a nonequilibrium solid solution of nickel and iron in the surface layer of tungsten particles upon high-energy ball milling are responsible for the decrease in optimal sintering temperature.

Two-dimensional unsteady gas flows in porous media with heterogeneous-combustion centers are investigated under forced filtration and free convection. With the use of numerical methods, it is shown that complex gas flows including vortex ones can arise under the combustion of solid porous media. In the case of forced filtration, the gas tends to flow around the heated portion of an object preferring to flow along cold regions. Under natural convection, the vortex gas flows, which can exist for a reasonably long time and strongly affect the oxidizer inflow into the reaction zone, arise at the initial moment of the process in the combustion zone and in its vicinities.

For a micropolar elastic medium with distributed dislocations and disclinations, an analogy has been established between the equilibrium equations for force and couple stresses and the reduced incompatibility equations for metric and bending strains. The strain boundary conditions have been derived. The physically different but mathematically equivalent boundary-value problems of the three-dimensional micropolar theory of elasticity have been formulated.

An investigation of the properties of the 67P/CG nucleus shows convincingly that some of the cometary nuclei resulted from low-velocity collisions of planetesimals. The hypothesis about the origination of a cometary nucleus from colliding bodies has long been known, but it is comet 67P/CG that has imparted topicality to it. In this paper we briefly formulate the combining or disruption criteria and show that in several cases the geometry of the cometary nucleus retains some information about the collision process and allows the impactor momentum to be found.

The efficiency of closed gas-turbine space-based plants is analyzed. The weight–size characteristics of closed gas-turbine plants are shown in many respects as determined by the refrigerator−radiator parameters. The scheme of closed gas-turbine plants with a gas-dynamic temperature-stratification device is proposed, and a calculation model is developed. This model shows that the cycle efficiency decreases by 2% in comparison with that of the closed gas-turbine plants operating by the traditional scheme with increasing temperature at the output from the refrigerator−radiator by 28 K and decreasing its area by 13.7%.