卷 13, 编号 3 (2024)

This article is devoted to the optimal parameter search for a magnetic focusing system to accompany a powerful relativistic electron flow using an accelerating voltage of 200-600 kV, a current of 1-5 kA for a 5 GHz microwave generator. For achieving this goal, the finite element method solves two-dimensional Poisson equations and the Runge-Kutta method solves an ordinary differential equations system. The developed mathematical model allows analysis and optimization of the parameters of a magnetic focusing system for an electron flow injected from a bladed cylindrical cathode in the cylindrical anode direction. The geometric and physical parameters of such a system offer the formation and maintenance of an electron flow with required parameters in a cylindrical electrodynamic system of a given diameter near its periodic structure. In the future, the created model can be combined with models and methods for designing ultra-high-power microwave generators based on corrugated electrodynamic structures.

Excitation equations for longitudinal-azimuthally irregular waveguides are formulated taking into account losses in the walls. The inner surface of the waveguide walls is given by an arbitrary smooth function b(φ, z). The coordinate transformation method replaces the original cylindrical coordinate system (r, φ, z) with a new one (ρ, φ, z), where ρ=r/b(φ, z). The new system defines the waveguide boundary as ρ=1=const, i. e. the waveguide geometry transforms as a regular cylinder. Taking these functions into account, the standard procedure of the incomplete Galerkin’s method is used to determine the amplitudes of partial waves. The resulting general equations can be used in the calculation and optimization of both microwave and EHF electronic devices of various types, as well as passive microwave devices of various applications.

The paper deals with the theory of photoelasticity on the example of linear isotropic dielectrics. On the basis of basic relations, an expression for the elastic-optical constant through dielectric susceptibility is derived. For three phase states of dielectrics, formulas for the calculation of the elastic-optical constant only on the basis of the value of the dielectric constant are derived. The maximum value of the elastic-optical constant in these media is estimated.

A description of the algorithm for optimal symbol-by-symbol reception of digital signals with reduced complexity of software implementation is given. The implementation of the algorithm is based on the use of an economical representation of numbers in the float format, which removes restrictions on the dynamic signal/noise range, on the length of codewords and on the type of signal “constellations”. The results of studies of the noise-immunity of the considered modified algorithm for optimal symbol-by-symbol reception of signal structures based on signal “constellations” of digital signals with multiphase shift keying intensively used in applications and on the simple correction code with parity checking in non-binary Galois fields are presented.

The article is devoted to the problem of interaction of modulated electromagnetic fields with living biological objects (LBO). The organism is considered as a multiscale dynamic nonlinear system, at the upper levels of the hierarchy of which there is a set of various low-frequency self-oscillations, and, in accordance with the theory of nonlinear dynamic systems, it can be sensitive to the influence of external variable low-frequency fields, generally speaking, of different physical nature. The presence and nature of this sensitivity is determined both by the dynamic properties of reinforced concrete systems and by the time-frequency structure of the influencing fields. Under certain conditions, the influence of external variable low-frequency fields can qualitatively change the dynamic state of living biological objects, even at fairly low intensities of influence.

High-frequency electromagnetic oscillations, fields and radiation, along with low-frequency ones, are an integral part of the external oscillatory environment for living biological objects. Unlike low-frequency fields, within the framework of the dynamic model under consideration, high-frequency fields do not directly interact with the liquid concrete. It has been suggested that the interaction of high-frequency radiation with the liquid-breeding agent within the framework of a dynamic model can be realized due to its modulation by low-frequency processes characteristic of the oscillatory systems of the body itself. In this case, high-frequency electromagnetic radiation acts as a carrier of analog information in the form of low-frequency oscillatory patterns, creating a communication channel through which these patterns are delivered from one point in space to another. In the process of interaction of radiation with a living object, in a number of cases, direct demodulation of the initial high-frequency oscillations can occur, resulting in electrical or other physical types of oscillations characteristic of internal processes in living organisms themselves. Examples of such interactions are known and are given in the article.

Methods of mathematical statistics are described, which make it possible to monitor the quality of aerospace systems during its experimental research and to signal in advance about possible violations during quality control of equipment. It has been established that forecasting the average number of failures for aircraft equipment (BO) of aerospace equipment as a whole must be performed when a small number of failures are given for individual units in full and their prediction for the assigned operating time for these units leads to significant errors. The article proposes a method for planning and conducting equivalent-cyclic normal control and determination tests of on-board equipment (BO) for reliability, as well as equivalent-cyclic accelerated control tests of electronic and electrical BO of aircraft and spacecraft for reliability. Equivalent-cyclic determinants are proposed to assess the actual values of the achieved reliability levels of the BO.

An algorithm for creating highly efficient solvers to address current problems, based on solving diffraction problems of electromagnetic waves and other types of waves, is presented. The algorithm is based on the application of heuristic methods of diffraction theory. The recently proposed method of fundamental components, which differs from traditional heuristic methods by including a tuning procedure, allows for the creation of highly efficient (i.e., fast and accurate) solvers, opening new possibilities for studying current scientific and technical problems.

A system for frequency correction of the radiation pattern characteristics of an acoustic antenna array is proposed. The system allows you to improve the parameters of the antenna by using frequency division of the spectrum of the emitted signal, followed by spatial division of the signals across array elements. The characteristics are analyzed and the results of system modeling are presented.

Various methods of non-destructive testing are used to determine the degree of degradation of objects (nodes, devices, systems) operating at elevated temperatures are used. One of the most effective methods is ultrasonic flaw detection, which is based on piezoceramic materials that maintain the stability of parameters when the temperature of the controlled object changes over a wide range. The purpose of this work was to develop new piezoceramic materials of the oxifluoride type, manufactured based on phases of the BiFeO3 – BaTiO3 – BaFeO2F system, which can maintain high piezo parameters for a long time (d33 ≈ 150 pC/N) at temperatures up to 330°C. The technology includes a) a low-temperature method for the synthesis of ultrafine powders (UFP) of phases of the composition Bi0.67B0.33Fe0.67+xTi0.33-xO3-xFx (0