Decision making methods of the theory of possibilities, based on minimization of possibility and/or necessity of losses determined by the decision, are considered.
Show AbstractBasing on the cell-structure expansion method, statistical thermodynamics and structure of rigid oxygen are constructed. It is demonstrated that the structure of all its three phases can be described with high accuracy using the two-center interaction potential.
Show AbstractIt is shown that the area of an inversion domain in the magnetic field of a spiral galaxy decreases linearly in time irrespective of the inversion domain shape. This linear dependence occurs because the drift velocity of the transition layer bounding the inversion domain is proportional to the layer curvature (or, which is the same, is inversely proportional to the radius of curvature). The lifetime of an inversion domain of arbitrary shape is calculated. It turns out to be proportional to the initial area of the inversion domain. The evolution of multiply connected inversion domains (i.e., domains whose interior contains some additional inversion domains) is investigated.
Show AbstractA mathematical model describing transient processes in semiconductors has been studied. It has been shown that the original physical statement of the problem is reduced to the initial-boundary-value problem for a higher-order partial derivative equation of the composite type. Consideration of an appropriate one-dimensional initial-boundary-value problem has revealed full agreement of theoretical results obtained based on the proposed mathematical model with the observed dynatnic effect of space charge stratification in a semiconductor.
Show AbstractAn adaptive algorithm for detecting weak "gravitational" pulses, correlated with astrophysical processes, against the background of stationary noise with unknown distribution is developed.
Show AbstractUsing the example of the ionosphere radiotomography, a nonlinear statement of the ray tomography problem with inclusion of sounding ray refraction is considered. It is shown that, in the case of weak refraction, the nonlinear tomography problem can be solved as a sequence of linear problems whose solution process is realized by an iterative procedure with every approximation of the refractive index calculated using the ray trajectory obtained in the preceding approximation.
Show AbstractThe generation of a reflected wave with a frequency of $3\omega_1-\omega_2$ under inclined incidence of two elliptically polarized plane waves with frequencies $\omega_1$ and $\omega_2$ on the surface of an isotropic gyrotropic medium is studied. It is shown that the generation is most efficient in grazing reflection of the wave with a frequency $3\omega_1-\omega_2$. It is found that there exist such incidence angle ranges wherein the reflected wave becomes nonuniform, and its amplitude decreases exponentially with distance from the medium surface.
Show AbstractThe thermal processes occurring in biological tissues exposed to focused ultrasound are numerically modeled. The temperature field distribution is computed by means of an inhomogeneous heat conduction equation containing a relaxation term, and the acoustic field is specified in the form of a focused Gaussian beam. It is demonstrated that increasing the intensity and reducing the exposure time at a constant irradiation dose typical of therapeutic treatment improve the heating process localization and efficiency.
Show AbstractBased on the model having regard to quadrupole interaction, magnetic properties of antiferromagnets consisting of two and four magnetic sublattices have been investigated. Resonance spectra conditioned by exchange interaction have been found. It is shown that the frequencies of spin waves have an acoustic and an optical branch.
Show AbstractThe kinetics of magnetic transformation of the $\gamma$-Mn$_3$Ga alloy in the $\varepsilon'$-Mn$_3$Ga state with the crystal lattice tetragonal distortions of the DO$_{22}$ type has been studied. The $\varepsilon'$-Mn$_3$Ga phase is a ferrimagnetic nonergodic state where a double transition (paramagnetism-ferrimagnetism-ferrimagnetic spin glass) occurs on heating. The transition temperature strongly depends on the field magnitude. To explain the results obtained, a generalized Sherrington-Kirkpatrick theory of two component magnetic substances has been used.
Show AbstractX-Ray studies of thin multilayer Pd/Fe films were performed for samples with a fixed thickness of Fe layers ($\sim$6 Å) and a variable thickness of Pd layers (6-40 Å), samples with a fixed thickness of Pd layers ($\sim$30 Å) and a variable thickness of Fe layers (6-27 Å), and a sample with Pd and Fe layers equally thick ($\sim$9 Å). Films with Fe and Pd layers about 6 Å thick were shown to be structurally homogeneous. An increase in the Pd layer thickness caused the appearance of a structure modulated (quasi-sinusoidal) with respect to the concentrations of the components. If the thickness of Fe layers was 9 Å or more, a modulated FCC-Fe phase separated. In the presence of Pd layers 30 Å thick, a multilayer structure with the thickness of Fe layers reached 23 Å formed.
Show AbstractBy the data of full-scale experiments, the features of turbulent heat diffusion in a suspension flow are investigated. The methods for the process theoretical description are developed. A unique method for computing the turbulent thermal diffusivity vertical distribution is proposed. Comparing this distribution with the momentum and suspension transfer coefficient profiles, the regularities of the Prandtl and Schmidt numbers variation with altitude above the bottom level are identified. Mechanisms of the effect of suspended matter on heat transfer in an internal-wave flow are analyzed. The observed effects are described by a semi-empirical dependence of the Prandtl number on the Richardson and Turner numbers.
Show AbstractUsing techniques for predicting cyclic variations in radiation fluxes from the Sun, the parameters of quasiperiodic variations in radiation fluxes from stars of late spectral classes in the $H$ and $K$ chromospheric lines of ionized calcium are obtained.
Show AbstractThe application of the modeling potential method suggested by the author to the construction of the energy spectrum of the Schr$\stackrel{..}{o}$dinger equation with a potential of the form $|x|^{N}$ is considered. The modeling potential is taken to be the potential of a harmonic oscillator. Estimates are presented for the residual terms in the zeroth-order and first approximations.
Show AbstractA novel efficient compact tunable monochromatic X-ray source is proposed. The radiation is generated by electrons with a moderate relativistic energy (2-5 MeV), repeatedly crossing a thin crystalline target placed in a special magnetic field. Computer modeling shows practical feasibility of creating a magnetic field that will provide stable circulation and extraction of electrons. Estimates of the possible parameters of an actual device are given.
Show AbstractBy semi-empirical methods of quantum chemistry, the most probable configurations of molecules of plastoquinones in different states and herbicides that inhibit electron transport at plastoquinone binding sites are determined. It is shown that plastoquinone in a once-reduced state has a turned end group. The structure of a diuron molecule is similar to that of a once-reduced plastoquinone which may be the factor responsible for strong binding of a diuron molecule with the binding site of quinone $Q_B$ at the reactive center ofphotosystem II.
Show AbstractTo find optimal two-pulse solutions for direct transfer from the 185.2-km satellite orbit to the Ls collinear libration point, a restricted planar circular three-body problem in the Sun-Earth system is studied. Two trajectory families, "fast" and "slow", are found. For both families, in order to test the feasibility of applying a third pulse for further optimization, the absolute values of Lawden's basis vector are calculated.
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