Vol 60, No 6 (2017)

Based on the phenomenological consideration of the drift and carrier heating processes in the bulk of the А^IIIB^V type semiconductors in strong crossed electric and magnetic fields, a quasi-three-dimensional model describing main kinetic components of the current parameters is constructed. The behavior of the diffusion coefficient under these conditions is analyzed. It is found that the inequality of the longitudinal and transverse components of the effective mass and kinetic energy leads to strong differences in the components of the diffusion coefficient and drift velocity. The behavior of the drift and diffusion characteristics in magnetic fields with various induction intensities is analyzed. It is revealed that when the magnetic induction increases, the value of the longitudinal component of the velocity increases, and subsequently, falling sections appear on the drift transverse induction characteristic, which indicates the possibility of using this effect to create nonlinear inductive active elements. Anisotropy is observed on the transverse diffusion induction characteristic, which is manifested in the fact that for large values of B_z > 2 T, splitting of the maximum in two components occurs, which is also promising from the point of view of creating a new class of converter devices.

An analytical method for calculating the matrix elements of the Hamiltonian of the torsion Schrödinger equation in a basis of Mathieu functions is developed. The matrix elements are represented by integrals of the product of three Mathieu functions, and also the derivatives of these functions. Analytical expressions for the matrix elements are obtained by approximating the Mathieu functions by Fourier series and are products of the corresponding Fourier expansion coefficients. It is shown that replacing high-order Mathieu functions by one harmonic leads to insignificant errors in the calculation.

The name of the fourth author should read A. N. Ponomarev.

Within the framework of the modified potential cluster model with forbidden states which follow from a classification of orbital states of clusters according to Young tableaux, results of a calculation of the total cross section and astrophysical S-factor at energies up to 2.5 MeV are presented. It is shown that the implemented model and methods of classification of cluster states according to the Young tableaux enable, on the whole, a valid description of the available experimental data for the total cross sections and the astrophysical S-factor of the process of ²H³He capture in the energy range from 200 keV to 1.4 MeV.

On the basis of the special relativity theory (SRT), the mean density of matter in the Universe is calculated with the relativistic kinetic energy of receding galaxies taken into account. Within the framework of the general relativity theory (GRT), we estimate the influence on the mean density of the effect of gravitation. A contradiction between the hypothesis of dark energy and conclusions following from SRT and GRT is noted.

The polarization method of determining the bearing and the roll angle of a mobile object with two-channel radio beacon systems based on vector properties of radio beacon signals transmitted from two spatially separated points and amplitude-based and phase-based processing of the resultant vector signals received onboard the mobile object in the circular polarization basis is considered.

The paper examines the mechanism of nanocomposite reinforcement in the case of PMMA / functionalized carbon nanotubes with ultra-small nanofiller content. It shows that the real anisotropy level of carbon nanotubes is determined by their structure formed in the polymer matrix of a nanocomposite. This real anisotropy level, in its turn, determines the higher than normal degree of reinforcement of the examined nanocomposites. It also demonstrates the possibility of modeling the carbon nanotube structure as a macromolecular coil of branched polymer.

The paper presents transmission electron microscopy (TEM) investigations of ɛ-copper formation in ferritic grains and perlitic colonies of irons and steels alloyed with copper. It is shown that copper-enriched inclusions substantially differ in size and shape. The most disperse are particles produced by decomposition of α-phase in iron due to oversaturated copper. The size of particles appeared after austenite decomposition is approximately an order of magnitude larger. After the formation of ɛ-copper particles in ɛ-phase, they incorporate both in ferrite and partially in cementite laminas during the formation of lamellar perlite. Fine particles of ɛ-copper locating inside ferritic grains and in ferritic layers in perlite, restrain the dislocation mobility and have an additional hardening effect on iron-carbon alloys.

The problem of stability of a mixture of two liquids between two conductive plates separated by characteristic distances about several nanometers is considered. In this case, an additional term appears in the expression for the Helmholtz energy, which depends on the distance between the plates and also on the dielectric permittivity of the liquids. The thermodynamic properties of such a system differ from those in the bulk of the system. The influence of the additional term is demonstrated by numerical solutions of two problems: 1) computation of the parameters of the mixture between the plates, when there is a thermodynamic equilibrium with the same mixture in the bulk; 2) computation of two states of the mixture that can coexist in thermodynamic equilibrium between the plates.

Within the framework of the linear thermal elasticity theory a dynamic thermoelastic bending of a whisker crystal is considered under conditions of its irradiation with a high-current electron beam of nanosecond duration. It is shown that the characteristic time of leveling the temperature of superthin pin-type rod nonuniformely heated over its thickness is comparable with the period of the fundamental wave of flexural vibrations. This gives rise to a considerable decrease in the bending amplitude, which is concurrent with the heat conduction processes.

With the aim of obtaining preliminary estimates, the Monte Carlo method has been used to solve the nonstationary equation of laser sensing of an optically dense, complex, multicomponent aqueous medium by a monostatic lidar equipped with a photodetector array mounted on board an aircraft. The influence of the air–water interface, the contribution of multiple scattering of radiation by the water column, and reflection of the signal from the bottom are all taken into account. Estimates of the dependence of the power of the lidar signal recorded from the surface and the bottom have been obtained for different optical characteristics of the medium and brightness of the solar illumination. The field of view of the photodetector array is translated along the direction of flight of the aircraft with relatively low velocity. A combined image of the investigated space is obtained by joining together the sequentially taken rectangular images. Here, each pixel of the frame images distance and the sum of all these pixels gives a three-dimensional image of the ocean surface and bottom. Results of statistical simulation show that a lidar system for sensing the ocean water column using a detector array can be realized on a level that can justly be termed state-of-the-art. Under favorable conditions, it is possible to sense water depths up to 44 m.

The special features of the multiplet structure in spectra of sensitized acenaphthene phosphorescence caused by triplet-triplet energy transfer from 2,7-dibromodiphenylen sulfide (the energy donor) molecules in n-hexane matrices are investigated at 77 K. It is demonstrated that the distribution of intensities between components of the multiplet in quasi-line spectrum of sensitized acenaphthene phosphorescence depends on the freezing rate of the solution and the exciting pulse duration. The possible reasons for these dependences are discussed.

The energy spectrum of fullerene C₇₀ is obtained within the framework of the Hubbard model in the static fluctuation approximation. The energy states are classified and the allowed transitions in the energy spectrum of fullerene C₇₀ are determined using the methods of group theory. Assignments of optical absorption bands experimentally observed for C₇₀ fullerene are suggested based on this spectrum.

Photoionization of atoms by ultrashort electromagnetic wavelet pulses is investigated within the framework of a statistical model. Integral representations of the total probability of atom ionization are obtained within the time over which the pulse acts. It is shown that the dependence of this probability on the pulse duration in the considered case is bell-shaped. The wavelet pulse duration at which the maximum photoionization probability is reached is determined for different charges of atomic nuclii.