Pleiades Publishing Ltd

Computer simulation is carried out for the process of formation of electrohydrodynamic flows emerging in a system of two parallel wires as a result of symmetric injection from each electrode (2D case). Simulation is performed using the ANSYS system. A simulation algorithm is developed for nonstationary electrohydrodynamic flows. The results of simulation are presented. Analysis of the results shows that the evolution of electrohydrodynamic flows is accompanied by the formation of thin oppositely charged liquid streams moving in opposite direction from near-electrode charged layers.

A two-stage process based on selective chemical etching induced by metal nanoclusters is used to fabricate nanostructured surfaces of silicon plates with a relatively low reflectance. At silicon surfaces covered with silver nanoclusters, the SERS effect is observed for rhodamine concentrations of about 10–12 M. At certain technological parameters, the depth of the nanostructured layer weakly depends on the conditions for the two-stage etching, in particular, etching time. Under otherwise equal conditions for etching, the rate of the formation of textured layer in the p-type silicon is two times greater than the formation rate in the n-type silicon.

When a high-power laser beam is focused in a nonlinear Kerr medium, beam self-diffraction by induced inhomogeneities of the refractive index is observed. A method for calculating the field amplitude and phase in the focal region with regard for self-diffraction by self-induced inhomogeneities is developed. Computer analysis of saturable Kerr media showed that the optical-field region with the least cross section of the focal pattern is followed by that of chaotically radiating “splashes” and long filaments. The latter radiate outward from the region of the caustic waist over long distances. They represent bright spatial solitons, which channel a significant portion of the primary beam energy. No less than 8–12 clear-cut solitons traveling in the positive z direction and moving apart in the transverse (x, y) plane are observed in the cross section. The field amplitude oscillates along each of the solitons. Various parameters of the saturable Kerr medium are taken into account.

The variation of the photoacoustic signal near the mouths of radial cracks in Vickers-indented externally loaded Al2O3-SiC-TiC ceramics is studied. A theoretical model of a photoacoustic signal that is recorded near the mouths of vertical cracks is suggested. Indentation zones in Al2O3-SiC-TiC ceramics are visualized by laser scanning photoacoustic microscopy. The sensitivity of the photoacoustic method with piezoelectric detection of signals to both normal and shear stresses acting on a crack is demonstrated. Experimental and theoretical data for the effect of external stresses on the photoacoustic signal near the mouths of radial cracks are compared. For the ceramics under study, agreement is fairly good. It is shown that the strain coefficients near the mouths of vertical cracks can be determined from photoacoustic experimental data.

A method for characterizing a current total step in the I-V characteristic of a Josephson junction array is considered. In this method, an appropriately selected approximating curve is statistically fitted to the experimentally found curve. A self-calibration algorithm for an array of junctions incorporated into programmable voltage standards is suggested.

A complete system of equations describing the evolution of the phase composition of islands in the Ostwald ripening stage during the growth of thin films is derived and a solution is found. The distribution function of islands of solid solutions is obtained for different growth mechanisms. A general approach to controlling the phase composition and associated properties (electrical, optical, strength, and so on) in the multicomponent systems formed is developed. The investigation is conducted for the example of thin multicomponent films. It is shown that the greatest possibilities for controlling these properties are at the Ostwald ripening stage and in the presence of nonlinear phenomena such as self-oscillation or self-organization. A relation is found between the size and composition of the new-phase nuclei which form during the condensation of films of solid solutions. A system of equations describing the evolution of the distribution function of properties in island films of solid solutions as a function of the external parameters of the system is derived and solved. It is shown that a strong dependence of the composition on the external parameters appears for islands with radius R⩽10−8 m, irrespective of the type of material. A diagram of the coexistence of the corresponding properties in concentration-temperature coordinates is constructed for island films of stoichiometric compounds; this makes it possible to determine the necessary conditions for obtaining such films. It is predicted that various properties in multicomponent systems which undergo a first-order phase transition can vary periodically in time and space.