Journal of Experimental and Theoretical Physics最新文献

Using the approach developed by one of the authors, possible values of solar electron neutrino deficit has been obtained. The results can be verified in future experiments. The prospects in developing the computational method have been indicated.

Background. The aim of the work is to solve the inverse problem of diffraction on flat objects. Materials and methods. The initial problem is reduced to solving an integral equation. This equation is solved numerically. A modern two-step approach has been used to solve the inverse problem. Various types of field nonlinearity functions are used to simulate a nonlinear process. Results. A numerical method for solving the problem of diffraction on flat objects is implemented programmatically. Graphical images illustrating the value of the permittivity inside the body for the initial problem and the reconstructed values are presented. Graphs of convergence of the iterative process of modeling a nonlinear field are shown. The results of solving the problem taking into account different values of the nonlinearity parameters are presented. Conclusions. A numerical method for solving the problem is proposed and implemented, and comparative results are obtained. This approach to the solution can also be used for more complex nonlinear problems.

The conditions of soliton formation in a liquid crystal layer for generation of a pair of photons in an entangled quantum state (biphotons) during quantum calculations are considered. The geometrical dimensions of the soliton generated by a pulse of optical radiation, its dynamics and stability are estimated by using the knowledge of the liquid crystal physical parameters as well as its non-linear optical properties. The possibility of overlapping of optical solitons neighboring in space or time (or regions inside the liquid crystal layer, in which the deformation induced by the light wave field from successive light pulses occurs) is considered. In nematic liquid crystals (LCs), it is possible to obtain single solitons with spatial size of several tens of micrometers and less, the formation time from fractions of a millisecond to tens of milliseconds, and the existence time from fractions of the millisecond to hundreds of milliseconds. On this basis, it is possible to “encode” entangled states with a high level of signal distinction and to carry out quantum calculations.

Based on the formal theory developed by one of the authors in previous publications, the mechanism of interconvertibility in the system of neutrinos and antineutrinos ν_e, ν_μ, ν_τ, ({{bar {nu }}_{e}},{{bar {nu }}_{mu }},{{bar {nu }}_{tau }}) is considered; this system is treated as an aggregate of N = const identical microscopic objects in N_S = 6 states with the possibility in principle to explain the “deficit” of solar electron neutrinos. It has also been found that the best agreement with experiment is observed for systems of ν_e, ν_μ, ν_τ (i.e., for N_S = 3).

A system consisting of a constant number N of identical objects, each of which can be in one of N_s ≥ 3 states connected, by definition, by probabilistic relations, is analyzed. The values of these probabilities are determined, as well as the average numbers of the objects in the states and their minimum and maximum possible values, which determine the ranges of variation of these quantities. In particular, the results of this study can be used in the physics of microscopic objects (e.g., atoms) that also exist in hypothetic spaces with dimensions D > 3 (including the values of D = 5, 9 appearing in some models of the field theory). Apart from such a purely scientific value, this study is of the methodical interest as an illustration of basic concepts of the probability theory as applied to the problem under investigation with a possible application in combinatorics.

Hydraulic jump is one of the widely used phenomena in open channel flows. Yet a very limited study has been done on hydraulic jump and effects of tail gate. Recognizing the importance of flow depths in hydraulic jump analysis, the objective is to develop predictive equations based on the known tail gate opening (TGO), as the direct measurement of flow depth in the channel is not always feasible. Present study proposes theoretical as well as dimensional analysis model for predicting downstream flow depth of hydraulic jump using TGO. The models are developed for a specific range of experiments and are validated with additional experiments for extended range. The performance of both the models is evaluated using the statistical indices R², MAPE, and RMSE. The results indicate that both the theoretical and dimensional analysis models predict the flow depth of hydraulic jump precisely, offering a reliable and efficient alternative to direct flow depth measurements.

Using some results of our previous investigations, we calculate the probabilistic parameters describing the transformations ν_i → ν_j, ({{bar {nu }}_{i}}) → ({{bar {nu }}_{j}}) (i, j = e, μ, τ; i ≠ j), and ν_i ( leftrightarrow ) ({{bar {nu }}_{j}}) (i, j = e, μ, τ), which occur, among other things, with the nonconservation of the neutrino lepton numbers, as well as average numbers of ν and (bar {nu }). A possible contribution of such mutual transformations to the known effect of solar neutrino deficit is considered.

The aim of this work is a theoretical and numerical study of the scalar problem of diffraction by a system of acoustically soft screens. Material and methods. A rigorous mathematical formulation of the diffraction problem is considered; the Galerkin method is used to numerically solve the system of integral equations. Results. The theorems on the existence and uniqueness of the solution to the diffraction problem are proved; in particular, ellipticity and continuous invertibility of the operator in the system of integral equations are established; the convergence of the Galerkin method is proved. Conclusions. Important results on the solvability of the diffraction problem have been obtained; the projection method for its numerical solution is theoretically justified and implemented.

Using probabilistic concepts of traditional quantum mechanics, a formal interpretation is proposed for the familiar fact of deviation of the “number” of solar electron neutrinos from the theoretical value obtained based on the generally accepted concept of their generation at the center of the star. The results of this study are in concordance with experimental data.

The purpose of this study is to develop an effective noninvasive method for determining the properties of an object. To this end, the inverse diffraction problem is solved using combined or generalized computational grids. In this paper, both the direct and inverse problems are described. The result of solving the direct problem follows from the solution of the corresponding volume integral equation. The inverse problem is solved using a two-step method. A numerical method is described in detail. Numerical results have been obtained, and solutions to the problems with noisy and noise-free input data have been compared.