The article proposes two types of multibeam spherotron-diotron based on a two-spherical resonator (an early article suggested a spherotron-diotron with non-synchronous interaction on a bi-spherical resonator, where the electron beam in this generator passes along the resonator z axis from the outer sphere to the inner one and interacts with the longitudinal (axial) electric resonator field). The first spherotron type has electron beams going from outer to inner sphere with slope ϧ about the z-axis: ϧ=0, π/8, π/4. The electrons interact with the resonator field through the emergence of quadratic forces in the field increasing along the electron motion. The second type (inverted spherotron) has electron beams located in half arc of the equatorial resonator plane, and the electrons move from the inner sphere to the outside. The interaction in it is carried out due to the spatial electron phasing. Both spherotron types achieve efficiency of 30 % at ultra-high pulse power and tens of kuloampère of total beam currents. The data presented in the article indicate the prospects of broad application for the inverted spherotron by the following indicators: extreme ease of design; no precision gratings or combs are required with a step significantly shorter than the wavelength; no focusing magnetic systems are required; electronic efficiency from 26 to 45 % is ensured. Note that the spherotron is fundamentally a highpower device (10-100 MW in a 1-10ns pulse) for in order to maintain the efficiency of non-synchronous interaction, one needs a high strength of the electromagnetic field, which is achieved only with a high-power device.

This article is devoted to the analysis of the total spectral radiation density of LTE subscriber terminals. The LTE network uses orthogonal frequency division multiple access (OFDMA) technology for downlink communications, and multiple access technology with single-carrier frequency division multiple access (SC-FDMA) for uplink communications. In a downlink, the occupied radio frequency band is determined by the number of resource blocks and the size of the step of placement of subcarrier oscillations in the frequency domain. Features of the technologies used for organizing multiple access in LTE networks determine the nature of the spectral density of the total radio signal. Thus, in a downlink, the spectral density approaches uniformity, since the power distribution in the spectral region does not depend on the number and location of resource blocks allocated to the subscriber, and also does not depend on the territorial location of the subscriber itself. For an uplink, the determination of spectral density characteristics is not so unambiguous, since they depend on a number of factors (traffic parameters, the nature of radio conditions, etc.). Тo conduct a detailed analysis of the spectral radiation density of a set of LTE subscriber terminals, a scheme of the measuring unit was developed and experimental studies of the spectral density were conducted on the basis of the BSUIR research laboratory. The article presents spectrograms of a set of signals in the uplink of the LTE communication network, obtained for different time intervals and different places of observation. The conclusion is made about the possibility of using an equivalent uniform spectral density to describe interference effects from groupings of subscriber terminals of LTE communication networks.

The purpose of this work with its results presented in the article was to develop and transfer to the class of Reed – Solomon codes (RS-codes) the basic provisions of the theory of syndrome norms (TNS), previously developed for the noise-resistant coding of the class of Bose – Chaudhuri – Hocquenghem codes (BCH-codes), which is actively used in theory and practice. To achieve this goal, a transition has been made in the interpretation of the theory of RS-codes from polynomial to matrix language. This approach allows you to fully use the capabilities of Galois field theory. The main difficulty of RS-codes is that they rely on a non-binary alphabet. The same factor is attractive for practical applications of RS-codes. The matrix language allows you to break the syndromes of errors into components that are elements of the Galois field – the field of definition of RS-codes. The TNS for BCH codes is based on the use of automorphisms of these codes – cyclic and cyclotomic substitutions. Automorphisms of RS-codes are studied in detail. The cyclic substitution belongs to the categories of automorphisms of RS-codes and generates a subgroup Г of order N (code length). The cyclotomic substitution does not belong to the class of automorphisms of RS-codes – the power of the alphabet greater than 2 prevents this. When expanding the concept of automorphism of a code beyond substitutions of coordinates of vectors to automorphisms of RS-codes, homotheties or affine substitutions can be attributed, since they also form a cyclic group A of order N. It is shown that cyclic and affine substitutions commute with each other, which, generally speaking, is not typical for linear operators and substitutions. The group Г of cyclic substitutions, the group A of affine substitutions, and the combined AГ group of order N² generate 3 types of error orbits in RS-codes. The structure of the orbits of errors with respect to the action of groups A, Г and the combined group AГ is studied {231 words}.

The purpose of this work is to demonstrate the phased development of a mechatronic device, to describe the development process of the device design and software, to demonstrate the application of the theory of selected sections of mathematics and physics in robotics, and, in particular, linear algebra, geometry, computational mathematics, discrete mathematics and mechanics. The study was based on the mechatronic device, which had been designed by the youth team of the Republic of Belarus in preparation for the international robotics competition “First Global Challenge 2019”, which became the winner of this event. The article describes in detail the statement of the problem at this competition, identifies the basic requirements for the robot being built, provides a general description of the stages of building the device both during the design process and during the immediate implementation of the project, as well as substantiates the engineering decisions that were made during the design process. The stages that are of the greatest interest in terms of applying the theory of applied physics and mathematics are described in more detail. Particular attention is paid to the design and development of structural modules, as well as to the development of software for controlling the device. The robot is an experimental model that can be used in further research in the field of artificial intelligence, machine learning, automation systems, and is also a potential platform for teaching robotics at the level of specialized secondary and higher education.

The research is targeted at the development and testing of a hardware-software system for environmental monitoring of atmospheric air in real time. The relevance of creating the system is substantiated in the article where it is shown that one cannot obtain operational data on the degree of atmospheric air pollution using available means, although this information is important for the population of large cities and industrial centers. The results of the creation and use of the automated system for monitoring atmospheric air using the modeling of transfer of pollutants are presented. The system was based on a hardwaresoftware complex consisting of a microcomputer, pollution sensors, a wireless communication module, and an unmanned aerial vehicle. Real-time pollution indicators are processed in order to build up-to-date maps, including to provide the opportunity to choose the optimal route taking into account the adverse effects of pollution. The developed mobile application provides the opportunity for the end user to receive information on-line and make forecasts based on the data on wind strength and direction in the short and medium term. The OND-86 methodology, which is mandatory in the Republic of Belarus, was chosen as the main model for the transfer of pollutants in the air. Information about the strength and direction of the wind for building forecasts is taken from open Internet sources of weather data. Using real data on the mass of emissions, a map of the planned concentration is constructed, which is scattered in proportion to the distance from the source of the emission, taking into account the strength and direction of the wind. The forecast obtained in this way can be used to select the optimal route, optimize traffic flows and organize actions in emergency situations associated with leakage and emissions of harmful substances.

Semantic network model for representing data and knowledge was analysed. Selection of this model for working with text information was justified. The objective of automatic semantic network generation based on an arbitrary Russian-language text was formulated. Initial data, conditions and constraints necessary for network generation algorithm are listed. As a result of the part-of-speech analysis for each word and word order in a sentence, semantic relations between words are determined. The Lexeme dictionary was created to determine the part of speech of words in sentences. A set of question types used in the semantic network was selected. The number of relations in the network is regulated due to the possibility to use only necessary relation types when resolving a specific task. With that, the relations in semantic network can have very different types, which makes it a universal model for representing data and knowledge. The algorithm was developed which allows one to get answers for the questions asked. The semantic network model was generated automatically for the sentences considered. In the proposed algorithm the semantic network is interpreted as unoriented graph on which breadth-first search algorithm is used to find an answer. The proposed algorithms were implemented in a software tool which automatically generates the semantic network for an arbitrary text. The created software tool allows asking questions and getting answers to them based on the information which is stored in the semantic network. The experiments have shown that the generated semantic network gives correct answers to the questions posed. The network is modified by adding and removing information in it. There is a possibility to choose complexity of network structure depending on a specific task being resolved. The proposed approach for building and working with the semantic network allows one to process texts in various languages, to use it in information systems with natural-language interface, and to resolve such tasks as text classification and text search.

This paper presents the results of the work aimed at a study of the patterns of changes in the nonlinear electroencephalogram (EEG) parameters, including fractal dimension and self-similarity exponent, when the operator is irradiated with electromagnetic noise radiation. Together with the above-mentioned nonlinear parameters, a change in the spectral power density of the rhythmic components in EEG (delta-, theta-, alpha-, and beta-rhythms) has been studied. Investigation of the fractal dimension, self-similarity exponent, and spectral power density during irradiation was associated with possible changes of the parameters in the case of operator’s depression or minor depression. The radiation source was represented by a transistor electromagnetic-noise generator with the power of 30 mW operating over the frequency range of 5 GHz. The methods for calculation of the nonlinear parameters including fractal dimension and self-similarity exponent have been described. To realize the principal objectives of the work, the Java-based software was developed. The relevant literature demonstrating the changes in fractal dimension, self-similarity exponent, spectral power density of the delta-, theta-, alpha-, beta-rhythms in the case of depression and minor depression has been reviewed. Electroencephalograms were registered according to the “10/20” scheme using the MBN Neurocartograph electroencephalograph. The analyzed leads were Fp1, Fp2, T3, T4, P3, P4, O1, O2, F3, F4, C3, C4. As shown by the results of this work, there is no distinct depressive state of the operator exposed to electromagnetic noise radiation, judging by changes in the self-similarity exponent, fractal dimension, and spectral power density. However, when the operator was irradiated with electromagnetic noise radiation, the observed tendency in variation of the parameters was characteristic for minor depression.

The article gives the procedure of structurally parametric synthesis of multi-band frequency-selective circuits. A short characteristic of approaches to solve the problems of synthesis of the multi-band frequencyselective circuits based on the use of multifrequency resonators, frequency transformations and parametric transformations using numerical procedures of optimisation is given. The research presents a short description of three widely used estimation criteria of the characteristics of frequency-selective circuits: Taylor, Chebyshev and average-degree criteria. Expedients of an estimate of joint approximation of amplitude-frequency and phasefrequency characteristics of synthesized circuits to those of the ideal filter are shown. The criterion is suggested and the procedure is presented for structurally parametrical synthesis of multi-band matching circuits on the basis of intracavitary complex criterion of conformity to the ideal filter in a transmission band and interband Chebyshev criterion realized by numerical optimization of synthesized circuits relative to the chosen criterion for affinessy is given. With that, the multi-band circuit is represented in form of a ladder-type connection that, generally, consists of n different reactive resistances. The example of using the proposed procedure to solve the problem of structurally parametric synthesis of a two-band matching circuit is given. As a matching load we selected the first-type equivalent consisting of a serial connection of active resistance and capacity. In the example there is an additional requirement to ensuring interband frequency selectivity. Such requirement is ensured by introducing zero to the function of transmission of the synthesized circuit on an interband average geometric frequency. The requirement is implemented by introducing a parallel oscillating circuit to the first serial arm of the synthesized circuit. The structurally parametric synthesis of the two-band matching circuit selected in the example is carried out through Mathcad 15 software based on the integrated method of Levenberg-Marquardt optimization.

The formation of chromium disilicide layers on n-type single crystal silicon substrates (111) during rapid thermal annealing in heat balance mode by the methods of Rutherford backscattering, X-ray diffraction and transmission electron microscopy of cross sections was investigated. Chromium films of about 30 nm thickness were deposited by magnetron sputtering of a chromium target with argon ions onto silicon substrates at room temperature. The rapid thermal treatment was carried out in a temperature range of 200 to 550 °C in a heat balance mode by irradiating the substrates backside with a non-coherent light flux of quartz halogen lamps in a nitrogen ambient for 7 s. It was established that hexagonal phase of chromium disilicide formation with grain size of 150–300 nm occurs in a threshold manner when the temperature of rapid thermal treatment exceeds 400 °C. At the same time, there are strong changes in the films surface morphology and surface roughness, and a silicide-silicon interface occur. In this case the wavy film surface morphology practically repeats silicide-silicon interface morphology (the surface exactly replicates the interface). The mechanism of CrSi2/Si interface structure roughness formation based on consideration of Kirkendall effect and deformation-stimulated diffusion of vacancies is proposed and discussed. The research results of the structure and morphology of CrSi2 layers on silicon are well-correlated with the results of the Schottky barrier electrophysical measurements. The results obtained can be used in microelectronics for forming rectifying contacts and interconnects metallization for integrated circuits, as well as for thermoelectric and optoelectronic applications.

At present, the field of applications of powerful ultrasound is expanding intensively, and the improvement of equipment and technological processes continues. With that, the key factor in the effect of ultrasonic vibrations on processes in liquids and liquid-like media is cavitation, i.e. the phenomenon of formation, pulsation and collapse of gas microbubbles under the influence of variable pressure. The widespread introduction of promising ultrasound technologies is largely constrained by the fact that the patterns of cavitation generation are not well understood, and the data known in the literature are contradictory and are characterized by low reproducibility. This paper describes an innovative method for studying ultrasonic cavitation. In order to increase the reproducibility of the results and the reliability of the conclusions about the correlation of various cavitation effects, it is proposed to register simultaneously the parameters characterizing these effects. An installation designed to implement this method has been developed and tested. The installation provides the ability to register the full output signal of the hydrophone, the intensity of the glow generated in the cavitation region - sound luminescence, the cavitation noise spectrum and its individual components. Technical characteristics of the installation allow you to adjust the rate of development of the cavitation region by varying the duration and period of the ultrasound pulses. It is possible to conduct experiments both in low-frequency (LF) and high-frequency (HF) fields as well as in interacting HF and LF ultrasonic fields. During the testing of the installation, the results were obtained that are of considerable interest from the point of view of refining the ideas about the mechanism for generating cavitation effects. It was found that preliminary treatment of the liquid in an ultrasonic field with the aim of its degassing for 15–20 min provides a significant increase in the reproducibility of measurements, especially for liquids with a high gas content. Based on a comparison of the time dependences of the signals of the cavitation sensor and the photomultiplier output, the characteristic stages of the development of the cavitation region are distinguished, which differ in the dynamics of the development of the cavitation region and in the composition of the cavitation noise spectra recorded.

The purpose of the article is to estimate the leakage channel of a discrete-quantized speech signal with amplitude-pulse modulation. Discrete-quantized analog-to-digital conversion of signals in the article is considered by the example of pulse-amplitude modulation. Development of mathematical model of speech signal leakage channels during discrete-quantified conversion is based on the spectral representation of periodic signals by Fourier series. A periodic pulse train of triangular shape as a measuring signal is proposed. Measuring signal of triangular shape has an advantage over a harmonic signal in the process of quantization noise extraction because it allows one to achieve higher accuracy during signal processing. To evaluate the channel security caused by amplitude-pulse modulation, a harmonic signal is used, which is generated from a periodic pulse sequence of a triangular shape by the Fourier transform method. As a result of constructing the spectrum of the amplitude-pulse modulated signal, it was found that for each harmonic component of the spectrum corresponding to the spectrum of the periodic sequence of pulses, side components corresponding to the spectrum of the modulating signal appear. This side components, together with the low-frequency component in the band of the speech signal, form an information leakage channel. The presence of source modulating signal in the amplitude-pulse modulated signal spectrum allows one to digest the security of the leakage channel of the speech signal with amplitude-pulse modulation by the low-frequency component of the modulating signal. The materials presented in the article are original and can be used in assessing the security of leakage channels of speech signals converted into digital form. In addition, the results obtained allow further studies of the security of speech signals during their inverse transformation from digital to the original signal.

The paper considers a hypothesis concerned the possible influence of electromagnetic pollution of the environment on the lethality rate of the population from coronavirus infection, along with other factors. The hypothesis is indirectly confirmed by the correlation between the degree of rigidity of hygienic regulations of radio frequency electromagnetic background levels for the population, which are mainly created by mobile (cellular) communication systems, and the lethality rate from COVID-19 in various countries. A special measures to ensure the safety of rapid development of technologies, systems and services for mobile communications of the fourth (4G), fifth (5G), and, by 2030, the sixth (6G) generation, associated with an increase by several orders of magnitude in the number of radiating devices, the data transmission rates over radio frequency channels and the area capacity of mobile traffic, are discussed. For quantitative analysis of these processes, a practical method of worst-case estimation of electromagnetic background level generated by these systems has been developed, verified using the results of numerous measurements of the electromagnetic background in various countries, and described in this paper. This technique is based on the use of the integrated system characteristics of wireless information services and makes it possible to justify the necessary system, technical and managerial solutions aimed at ensuring the necessary level of electromagnetic ecology of populous areas and electromagnetic safety of people in conditions of rapid advancement of 4G/5G/6G systems without affecting the quality of informational support of the population and information technologies in economy, education, healthcare and other sectors.