A comparative analysis of the microwave activity of graphite of different grades, acting as receptors that contribute to the conversion of microwave electromagnetic energy into thermal energy, in the synthesis of carbon nanomaterials has been carried out. Ferrocene, a compound from the group of organoelement substances of the metallocene type, was used as a carbon supplier for the synthesized nanomaterials as well as a precursor of the iron catalyst for synthesis process. It is shown that, in all cases, microwave treatment of the mixtures of graphite with ferrocene leads to the formation of carbon nanostructures including twisted ropes of curved multi-walled carbon nanotubes of 16-70 nm in diameter with a characteristic matchstick morphology, containing catalyst particles at the ends, and included inside the tubes, and also encapsulated in carbon spheres; threedimensional graphite / CNT nanostructures, onion nanoparticles, the packets of graphene planes are identified. The data of electron microscopy (TEM, SEM) and X-ray diffraction analysis of the obtained nanoobjects are presented.

The dynamics of oscillations of a one-dimensional atomic chain is investigated in the harmonic approximation, taking into  account the retardation of interatomic interactions. It is found that the retardation of interactions between particles leads to a radical restructuring of the dynamics of a one-dimensional harmonic chain. In particular, due to the retardation of interactions, stationary free oscillations in the atomic chain are impossible. A criterion for the absence of growing oscillations in the system has been obtained, and this criterion is a condition for the stability of the chain. It is shown that when a stable chain of particles with retarded interactions between them is immersed in an alternating external field, the system passes into a stationary state, which depends both on the properties of the system and on the characteristics of the external field. This stationary state has been interpreted as a dynamic equilibrium between an atomic chain and an external field.

It is shown that taking into account the field, through which the interaction between particles occurs, and the causality principle allows us to derive a kinetic equation for a microscopic distribution function, which enables us to describe the irreversible evolution of a particle system without involving any probabilistic hypotheses. An auxiliary scalar field is introduced to explain the dynamics of a system of neutral particles (atoms) in the framework of the classical field theory. It has been proved that the class of stable interatomic potentials can be represented as a superposition of Yukawa potentials. A complete system of equations for the relativistic dynamics of a system consisting of atoms and an auxiliary field has been obtained. The proposed relativistic-field approach to describing the dynamics of systems can be used as a probability-free method for constructing microscopic thermodynamics and kinetics of both macroscopic and "small" systems, including nanosystems.

A new method for calculating distribution functions characterizing the degree of heterogeneity of macroscopic media is proposed. The introduced distribution functions are based on the smoothing procedure for a certain volume. The volume value is selected depending on the task of the study. It is shown that the distribution functions can be expressed in terms of local tensor fields, the use of which simplifies the procedure for closing the hierarchy of kinetic equations due to the transparent physical meaning of tensor fields. Based on the proposed method, the linear response problem is considered and an analytical expression for the reaction of the local density of the medium to a small external mechanical disturbance has been obtained. It is shown that the derived expression for the density distribution coincides with the result of the calculations carried out on the basis of the generating functional in the ergodic Weyl approximation.

A theoretical substantiation of the need for thermal stabilization of laser diodes, which are the pumping system of a solid-state laser, is presented. The article demonstrates a thermal model of the thermal stabilization system of the laser pumping system. Thermal stabilization of the laser pumping system has been investigated with the ambient temperature range from 218.2 to 333.2 K and the dependence of the temperature of the pump diode lines on the ambient temperature has been obtained. Limiting characteristics of the thermal stabilization system has been investigated with the ambient temperature range from 218.2 to 333.2 K and the dependence of the maximum allowable heat release power in the pumping system on the ambient temperature was obtained. The proposed and researched possible options for improving the characteristics of the thermal stabilization system, namely, increasing pump volume flow, changing the area of the internal surface of the heat exchanger, installation of thermoelectric elements with higher cooling capacity.

The article discusses a technique for forming a compact (SPICE) model of an integrated capacitor manufactured using bipolar technology based on the barrier capacitance of one of the junctions of a bipolar transistor. Unlike a discrete analog, an integral capacitor is characterized by a large number of parameters, which is associated with the presence of parasitic resistive and capacitive components. On the basis of the synthesized macromodel, a number of integrated capacitor characteristics were calculated, including capacitance-voltage and frequency dependences of the quality factor. The proposed procedure for synthesizing a compact model of an integrated capacitor can be used to form macromodels of other types of integrated capacitors based on a barrier capacitance, as well as MOS capacitors for dynamic memory and parasitic capacitances of integrated circuit interconnect buses.

The article is devoted to the principles of parameter calculating during permanent magnets and electromagnets interaction in a brushless electric motor, which is "radial-coil motor-wheel". Information is given on the distribution of mechanical forces in the engine, examples of the calculation of electromagnetic forces, information on the type of phase formation and the connection of windings in the motor-wheel. Calculations of the minimum required length of the conductor, as well as the number of turns of the conductor wound on the coil of the electromagnet, considering the radial arrangement of the electromagnet as part of the motor-wheel, are given. The application of the calculation methods described in this article allows one to create various configurations of electric motors and motorwheels to solve a wide range of tasks. The development of this technology in Russia will make it possible to reach a competitive level in the field of creating personal electric vehicles, robotics and other devices using electric motors.

The article presents a technology for measuring distances by emitting light (laser) and measuring the return time of this reflected light to the receiver. For this, modern devices are used — LIDARs, which are an active optical rangefinder. The architecture of the *.las file linker forming point clouds based on LIDAR data has been developed. The parameters that are measured by the LIDAR system and are the basis of *.las files have been considered. The structure and content of files with arrays of LIDAR data points have been studied. The result of the work is the development of an algorithm used to synthesize a 3D model of a scanned area and select the image of the desired object based on the cloud of environmental points. The advantage of the proposed method is the high accuracy of object detection (several centimeters at a distance of 100 meters) along with its versatility, which allows it to be used for a wide range of applications.

The article describes technical realization of compact UAV based X/L-band SAR. It presents a block diagram of the developed radar prototype and describes the structural diagrams of the main functional blocks: the signal generation and processing unit, the coordinate processing unit, the radar image generation unit. The estimation of the resources required for the implementation of signal processing of a programmable logic integrated circuit (FPGA) is given. Examples of radar images obtained during full-scale tests of the radar prototype are given at the end of the article. Novelty of design based on two main factors: broadband quasi-continuous signals (QCS) and the real-time land surface imaging. The usage of QCS leads to the higher stealthiness and noise-immunity. The peak power of transmitter is decreased also. This features are highly demanded while designing RSA systems that can be used on compact UAV.

The article describes technical realization of a compact S/C-band radar for the site protectrion. Nowadays, closed facilities, factories, and energy sector facilities, such as gas / oil pipelines are facing the problem of unauthorized access. The greatest danger in terms of untracked trespassing the border of the protected area in recent years are unmanned aerial vehicles (UAVs). Such UAVs allow not only to carry out high-quality photo / video, but also to carry cargo that pose a potential threat to the security of the object. The developed radar system provides all-weather and round-the-clock detection of small mobile targets. The use of the technology of the phase method of measuring the angular coordinates allowed us to remove the moving parts of the radar, significantly increasing its reliability, as well as to increase the service intervals. The use of wideband signals with a large base (quasi-continuous mode) provides increased noise immunity, secrecy and detection range.

Modern active phased antenna arrays (APAA) have a high packing density of receiving and transmitting modules (RTMs), the number of which can reach several thousand elements, depending on the tasks being solved. When the entire system is operating, the efficiency of the RTM is about 20–30%. As a result of the high packing density of the APAA elements, a large amount of heat is released, which must be dissipated. Due to low efficiency, traditional air cooling is used only in long-wave systems. Most modern active phased array antennas are cooled by liquid, as well as by organizing heat removal with the use of heat pipes. The article presents a method of thermal protection that allows to increase the reliability of the RTM. The results of thermal protection functioning are included.

The article discusses an additive-multiplicative model of fiхed pattern noise of an infrared photodetector and analyzes the effect of fluctuation noise on the process of two-point correction. The method of forming real test images is considered, as well as the method of computer simulation of test reference images of a uniform background with fiхed pattern noise mixed with fluctuation. The possibility of studying their separate influence on the amount of residual fiхed pattern noise is shown. The results of computer simulation are presented, showing the possibility of a correlation between the fluctuation components of noise, which are taken into account when calculating compensation coefficients and in the process of compensation itself, which leads to a change in the nature of the dispersion of residual fiхed pattern noise in images corresponding to intermediate values of average brightness between reference points. Dependency graphs and examples of real and computer test images of fiхed pattern noise of the photodetector are given.

In order to obtain reasonable practical results of the study of infocommunication systems and communication networks, as well as to put them into practice when solving deep learning problems, the article considers the software implementation of the task of analyzing uniformly and normally distributed random variables. Along with a theoretical analysis, the article presents experimental study results. Uniform and normal distributions are considered. A solution to the problem of transforming a random sample so that it obeys the standard normal distribution is given. The software generates sequences of random variables, which are summed element by element. The problem of calculating the density function, the mean value, and the variance of the sum of two uniformly distributed random variables has been solved. The transformation of a uniform distribution into a normal distribution has been performed. For two independent and uniformly distributed random variables, a two-dimensional density function has been defined. The software implementation has been performed using the Matlab mathematical modeling program. The results of theoretical studies and software implementation are shown in graphs.

A description is given of the design of a photodetector containing two back-to-back photodiodes. One of them is located on the illuminated side of the crystal, and the second one is on the back side. In the circuit of the first photodiode, it is proposed to use a connected additional external resistance. With the resistance turned off, the photodetector had a broadband spectral characteristic. The connection of an external resistance changed the broadband response to a selective one. Signal suppression in the short-wave region was due to its compensation by the back-to-back voltage across the bulk resistance of the base region. The high efficiency of suppression of short-wave radiation is shown by the example of a cryogenic InSb photodetector. In the selective mode of operation with a closed key, the short-wave signal was observed to be attenuated by almost 10³ times compared to the broadband mode with an open key.

The article discusses the main differences between hyperspectral systems (HSS) and multispectral systems (MSS), as well as the principles of formation of hyperspectral images (data hypercube) and their processing in order to analyze the spectral characteristics of the objects under study. In addition, options for constructing the HSS of the visible range based on the methods of spatial and spectral scanning are considered. The HSS of the visible range based on the Fabry-Pérot interferometer is described in detail. Its block diagram and operation principle are given. The technical characteristics of the designed HSS are analyzed, and the issues of mathematical and semi-natural modeling of the hyperspectral system are considered, which, in turn, allows minimizing errors associated with the analysis of spectral characteristics, and also provides the possibility of testing the algorithms of the HSS when solving object detection problems. Analytical expressions are given to evaluate the spectral selectivity of the system.

The technological cycle of manufacturing an active element of a pHEMT transistor with a gate length of 0.25 μm as part of a microwave monolithic integrated circuit based on gallium arsenide is considered. The main area of application of this technology is the design of monolithic integration circuits with operating frequencies up to the Ku-band (18 GHz). The requirements for the level of the main parameters of the integrated pHEMT transistor have been developed. As the initial heterostructure, we chose a pHEMT structure with two-sided filling of the channel with electrons that is a DpHEMT structure providing low noise figure and a high level of specific output microwave power. The methods of forming the metallization of a T-shaped gate, which improve the adhesion of a passivating SiO₂ film deposited later, have been considered. An analysis of the structures of the gate grooves of microwave pHEMT transistors has been carried out. The structure of low-temperature SiO₂ films obtained by chemical vapor deposition has been studied by Fourier-transform infrared spectroscopy. Photon annealing was used to eliminate the oxygen deficiency in the films. Ohmic contacts on the plate were created using lift-off lithography after the process of vacuum deposition of the required AuGe/Mo/Au/Mo metal system. This metallization system, which includes Mo, in contrast to systems based on Ni, has several advantages. The developed transistors for microwave monolithic integrated circuits of low-noise amplifiers and Ku-band power amplifiers satisfy the required level of the main parameters of the integral pHEMT gallium arsenide transistor.

A computer simulation of a metastructure based on four split-ring resonators with the inclusion of YIG (yttrium-iron garnet) ferrite elements on a GGG (gallium-gadolinium garnet) substrate was carried out in order to study the possibility of tuning the ferromagnetic resonance (FMR) line of 4 ferrite resonators under the influence of an external magnetic field. The design of a metastructure based on four split-ring resonators with YIG-GGG ferrite resonators and an equivalent resonator connection circuit are presented. This structure was considered earlier in terms of use for the development of a microstrip filter. The simulation was carried out using the Ansoft HFSS 3D modeling tool for RF/microwave fields. The obtained amplitude-frequency characteristics of the FMR show the possibility of resonance line tuning under the influence of an external magnetic field.

In modern time, the successful development of electronic technology is due to the research and industrial usage of new materials with a wide range of physical properties to design on their basis devices operating on new physical principles. The last few decades have been characterized by a significant increase in activity in the field of materials research, in which the relationship between electrical and magnetic properties is manifested. Of particular interest are magnetoelectric materials whose properties are manifested at room temperatures and relatively low magnetic fields since such materials are promising for practical applications. The design and principle of operation of a magnetoelectric microwave filter is presented. The simulation was carried out in the HFSS Ansoft program. The amplitude-frequency characteristics of the filter were obtained.

The paper outlines the basic principles of applying layered structures of a new type, magnetoelectric gradient structures, in the design of electronically controlled microwave devices. It is shown that magnetoelectric gradient structures are complex composites that consist of composite materials including a layered multiferroic and an artificial dielectric. On the basis of a previously constructed mathematical model by numerical simulation, the spectra of natural waves propagating in a magnetoelectric gradient structure have been obtained at different values of the applied external electric field and the relative permittivity of the artificial dielectric layer. The mutually contradictory nature of the influence of these factors on dispersion characteristics has been established, which lays the foundation for the development of design principles for new ultra-high-frequency devices, based on the layered composite material presented in the study.

The article presents the results of studying the magnetic resonance spectrum in ferrite-piezoelectric layered structures under the influence of an external electric field on the sample. An external electric field induces a magnetic anisotropy in the ferrite component, which is inhomogeneous in the thickness of the sample. The paper considers the solution of the equation of the magnetization motion of the ferrite component, taking into account the electrically induced magnetic anisotropy. The calculations take into account the bending deformations of the sample. For two-layer and three-layer structures based on yttrium iron garnet and lead zirconate titanate, the values of the broadening of the magnetic resonance line have been obtained. The optimal values of the layer thicknesses for obtaining the maximum broadening of the resonance lines have been found. The results of the work are of interest for the new ferrite-piezoelectric microwave devices.

A new, mathematically correct method of electrodynamic analysis of infinite antenna arrays is proposed. The method is based on the study of the properties of the Green's function of an infinite periodic array. At the first stage, the two-dimensional integral equation is reduced to a one-dimensional integral equation. Then, by isolating the main part, a continuously reversible operator, the structure of the equation is revealed. It is shown for the first time that the main operator is the same as in the problem of electrodynamic analysis of a unit radiator. A numerical-analytical method for calculating phased antenna arrays is proposed.

The Periodic Table of the Elements begins with the hydrogen atom whose properties determine its general features. Today, it is necessary to rethink the history of the creation of the theory, to simplify and modernize the methods used. This article discusses a number of common problems solved by uncommon methods, simple and short. All of them are based on a deep insight into the essence of the problem.

The concept of an intelligent chatbot is proposed, which combines the ability to integrate with popular instant messengers and a knowledge base updated based on user needs. The research and development of the class schedule bot of Novgorod State University for the social network VKontakte in the Python programming language was carry out. The task of the development was to improve the quality of service for students and teachers of the university through the introduction of a schedule chat bot. The chatbot displays the class schedule to the user by the name of the group or the name of the teacher. The development stages are described from collecting data from the university website to deploying a bot on a hosting. The API is also considered as a bridge between the university website and the bot.

This article raises the issue of attention concentration problem in distance and inclusive groups when studying. The possibility of using neurotechnologies in the educational process is substantiated. А possible solution to increase students’ attention to improve their academic performance, which will be a consequence of the assimilation of a large amount of material in a short period of time, using neural interfaces, is described. This allows the teacher to comprehensively assess the degree of readiness of the student's brain to perceive new information. The article also describes possible difficulties that may arise during the software development. The technical means of controlling the attention of students, available on the world market, their advantages and disadvantages are considered.

A method for calculating caloric effects in multiferroics, including magnetocaloric, electrocaloric, barocaloric, and multicaloric effects, is discussed. The possibility of increasing caloric effects in materials with a magnetoelectric effect, as well as the possibility of creating composite magnetoelectric materials, in which the application of one field leads to inducing the caloric effects of different physical nature, due to the mechanical connection between the components of the composite material, is considered. The results of the work are of interest in terms of obtaining a set of characteristics of layered structures necessary for the creation of solid-state coolers in order to increase the reliability of the element base of microelectronics.

In this article, it is shown that in harmonic coordinate systems the pseudo-tensor τ^αβ of the gravitational field energy-momentum is a single-valued function of macroscopic body properties.