Using the developed experimental setup, the effect of ultrasonic oscillations (USO) on the temperature and combustion velocity during self-propagating high-temperature synthesis (SHS) in the Ti–C, Ti–C–Ni–Mo and Ti–B systems is studied. Basing on the analysis of data known in literature and our own measurements, theoretical explanation to the observed results is proposed. The effect of the intensity of ultrasonic oscillations on the composition and structure of the final synthesis products is established. It was found that along with changes in the parameters of the combustion wave, the completeness of the interaction increases, and changes in the microstructure and phase composition of the reaction products occur. The concept of separation of the effect of USO on SHS into thermal, or macroscopic, and non-thermal, or microscopic is proposed. The former is associated with forced convection of gas around an oscillating specimen and leads to a decrease in temperature and combustion velocity. The latter is connected with a change in the melt spreading conditions, the progress of heterogeneous reactions and mass transfer in the liquid phase in the high-temperature zone of the SHS wave, which lead to a change in the phase composition and structure of the final product.

The influence of synthesis conditions on the magnetic characteristics of composite materials based on iron powders ASC 100.29 (Sweden) and LiaoNing (China) is investigated. The surface of metallic iron powders is encapsulated by an insulating ferrite coating, consisting of iron oxides and phosphides. The synthesis was carried out at a temperature of 150 °C from a gaseous medium in a special reactor at a pressure of 1 atm. Insulating oxide coatings were applied both to the initial iron powder without treatment, and to previously annealed powders in an inert atmosphere and in a mixture of hydrogen-argon. To conduct studies of magnetic characteristics, cores in the form of rings were made by pressing method. The dependence of induction vs. magnitude of the magnetic field, magnetization reversal losses (hysteresis losses) in the full and in the private loop were recorded by an express magnetometer. The value of losses was calculated by the hysteresis loops area. The results show that composite low-frequency magnetic materials based on metallic iron ASC 100.29 and LiaoNing powders have similar values of magnetic parameters – almost identical B = f(H) dependencies, but the magnetization reversal losses for ASC 100.29 are significantly lower than for LiaoNing powder under equal insulating coatings synthesis conditions. It is possible to use such materials as magnetic cores in various electrical devices, such as cores of high-frequency transformers and a number of electrical machines. Since such materials can operate at frequencies from 1 kHz and higher, this will significantly reduce the overall dimensions and increase the efficiency of electrical products.

Linear and mass ranges of protons and argon ions in aluminum, alumina, bismuth, and W_77.7Cu_22.3 composite shields were calculated using the SRIM software package. It is shown that the protection efficiency against high-energy ions by materials with large atomic charge (Z) values is higher, from the position of linear ranges of particles, and lower, from the position of mass ranges, in comparison with materials with low Z values. The dependence of the threshold energy on the serial number of particles for aluminum, bismuth, and composite W_77.7Cu_22.3 shields is determined. The ionization loss spectra for the passage of both protons with an energy of 20 MeV and krypton ions with an energy of 7.75 GeV through multilayer Bi/Al/Al₂O₃ and Al/Al₂O₃/Bi structures were calculated. These results showed that the braking of high-energy particles in the case when the first layer contains a heavy element is higher than in the case when the first layer contains a light element. The influence of the sequence in the arrangement and thickness of the layers in the multilayer structures of the Bi/Al/Al₂O₃ system on the efficiency of protection against high-energy ions was studied. It is shown that the nature of the dependences R(E) and ion energy losses are determined by the sequence of arrangement of individual layers, which is due to the difference in the conversion of the spectra by the material of the first layer. The studied radiation shields can be used in aerospace and nuclear technologies, as well as in many scientific and medical devices, and can be used to protect against the effects of a wide range of ionizing radiation (electrons, protons, heavy charged particles, etc.).

This article presents the results of the study of the effect of annealing on the sheet resistivity and temperature coefficient of resistance (TCR) of resistive films obtained from targets of the Cr–Ni–Si system using magnetron sputtering. A diagram of the composition–sheet resistivity of the Cr–Ni–Si system films with a thickness of 100 nm is proposed. It was established that resistive films of the Cr–Ni–Si system deposited by magnetron sputtering on silicon semiconductor plates with a SiO₂ sublayer with a thickness of 100 nm, have sheet resistivity up to 350 Ω/square. It is shown that it is necessary to determine their eutectic compositions for the manufacture of targets by casting. Calculations were carried out and it was established that eutectics of the Cr–Ni–Si system contain 36.4 and 38.5 at.% Ni, which is 4 to 6 times higher than in the PC series alloys of this system. Due to the high content of Ni sheet resistivity films of eutectic compositions with a thickness of 100 nm is in the range from 100 to 200 Ω/square. It was noted that it is necessary to develop new four-five-component alloys based on the Cr–Ni–Si system with the introduction of refractory (Mo, Nb) and rare-earth (La, Y) elements into it, in order to increase the sheet resistivity of films and to decrease the melting temperature of alloys.

Effect of activating the sintering process of powder steel alloyed with nickel or chromium by grinding the initial powders and introducing alkali metal compounds was investigated. The kinetics of grinding the initial iron powders, Cr30, and a mixture of iron powders with 4 % nickel was studied. It is shown that, depending on the hardness of the powder, it is grinded in three or two stages. When grinding more hard powders, there is no stage of intensive deformation of particles and an increase in their size. Crystalline lattice defects resulting from grinding of powders accelerate diffusion processes. This reduces sintering temperature by 100–200 °С compared to the sintering temperature of steels from the initial powders, contributes to a homogeneous structure, reduces porosity by 4–17 %, and increase strength of powder steels by 1.5–1.6 times. The mechanism of the effect of sodium bicarbonate on the acceleration of diffusion of carbon, nickel and chromium into iron has been established. With the introduction of sodium bicarbonate under the action of water vapor, formed upon its decomposition to carbonate, thin oxide films are formed on iron particles, which are actively recovered in a protective-recovering atmosphere during sintering. This leads to formation of a metal contact between the particles, acceleration of the self-diffusion of iron atoms and the diffusion of alloying additives into iron by 5–7 times, depending on the sintering temperature and the amount of added additive. Sodium forms nanodispersed complex compounds of the ferritic type Na₃Fe₅O₉ along the grain boundaries of the iron base, which provide grain refinement and the formation of a homogeneous structure. Changes in the structure of powder steel with the introduction of sodium bicarbonate cause an increase in its strength by 1.5–1.7 times. The results can be used to obtain structural products from alloyed powder steels.

According to the data of performed calculations and modeling of the hardening process, a design of inductors with magnetic cores for hardening long flat parts has been developed. At the design stage of this type of inductors, it was necessary to find out the degree of influence of the magnetic circuit design on the distribution of the temperature field during heating. To do this, we simulated electromagnetic and temperature fields to assess the concentration of the electromagnetic field at different heights of the “legs” of the inductor. As a result, a significant effect of the length of the “legs” of the magnetic circuit on the intensity of heating and the operability of the system as a whole was established. It is noted that insufficient height of the “leg” leads to a significant decrease in the field concentration, which leads to insufficient heating temperature and uneven distribution of heat zones in the heated part. In turn, an increase in the height of the “legs” leads to a narrowing of the heat release zone in the part compared to the total width of the coil and magnetic circuit. With a significant lengthening of the “legs”, the cooling circuit of the inductor will not be able to remove heat from the magnetic circuit obtained from the part, which will lead to the destruction of the magnetic circuit. The developed design of a two-turn single-circuit inductor and the general methodology made it possible to obtain a high-quality hardened layer with a depth of up to 3 mm with the formation of a martensitic structure of the required hardness on a planar-type flat part without significant energy loss. The part was machined by fixing it on a rigid base to compensate for the effect of temperature changes in linear dimensions. To obtain a uniform gap between the part and the inductor, a special pressure roller was used. The resulting structure of the hardened layer adequately meets the stated requirements for the part. The results of the research were used to develop a flat part of the “guide” type for lifting equipment (for example, a guide for the movement of the traction chain) and were introduced into production.

In the Republic of Belarus, on the base of JSC “Soligorsk Institute for Resources Saving Problems with Pilot Production”, the development and launch of import-substituting mass production of large-capacity double-drum mine winders with an increased diameter of winding drums up to 7 meters were fulfilled. Earlier, in the post-Soviet space, machines with similar technical characteristics were not produced. Accordingly, for the implementation of the project, a comprehensive study of all the scientific and technical aspects of the creation of this equipment was required, taking into account the material and technical capabilities of the enterprises of domestic mining engineering. One of the important results of this study was the development of an improved methodology for calculating the basic elements of a winder. The technique allows calculating the strength parameters of the winding drums, shaft, disengagement mechanism, drive elements (mating clutch), bearings together with their anchor fasteners, reduced to normal operating conditions and to conditions of emergency wire breakage. The methodology includes the calculation of the stress-strain state of the elements of the winding drums using the finite element method and allows using the obtained numerical data to simulate the stress-strain state of the main components of the hoisting machine to calculate its safety factors in normal operation and in emergency conditions. The developed methodology was successfully tested in the design and technological center of JSC “Soligorsk Institute for Resources Saving Problems with Pilot Production” during the development of double-drum mine winders with large diameter winding drums for skip hoisting units of the Petrikov mining and processing complex, as well as during the modernization of existing hoisting units at working mines of JSC “Belaruskali”.

The plasma of the atmospheric barrier discharge (PBR) is used to treat various types of diseases and damage to the skin and soft tissues; however, the mechanism of interaction of PBR with biological material has not been precisely established to date. One of the promising methods for estimation changes in the structure and properties of cell membranes at the nanoscale is atomic force microscopy (AFM). In this article the results of the influence of the barrier discharge low-temperature plasma on the structure and properties of erythrocytes and platelets are presented. By the AFM-method, the shape, morphology of membranes, and adhesive forces on the surface of the cells were determined, which is one of the characteristic parameters for assessing changes occurring at the molecular level with the cell membrane. In this work, we used an experimental complex for generating a low-temperature plasma of a dielectric barrier discharge based on a coaxial type device and an adjustable source power from 10 to 30 W. A change in the structure of the erythrocyte membranes without changing the shape of the cells themselves was established. On the non-fixed erythrocytes, the adhesion force is increased after exposure. On the surface of both erythrocytes and platelets, the presence of particles of submicron size was established, which may be due to the release of cell contents or the destructive effect of plasma on the proteins of the outer layer of the membrane. The cells, which are fixed with a 0.5-mm solution of glutaraldehyde on mica substrates, both retain their disk-like shape and membrane structure, which may be due to the formation of covalent cross-links between membrane lipids and glutaraldehyde, and residual liquid content in the cell volume after interaction with a chemical reagent. Red blood cells are more resistant to short-term exposure to PBR (1 minute) compared with platelets. The results of the studies can be used to establish patterns and the biochemical processes under the influence of PBR on blood cells.

The analysis of the state and prospects of development of autonomous electric power sources with electric reciprocating motion generators has shown that at present, low-power systems “free-piston engine – electromechanotron сonverter based on an electric reciprocating motion generator” are widely used. Studies of electric reciprocating generators have shown that special attention should be paid to combined generators that can improve the efficiency of such a system. However, until now, the study of the system “free-piston engine – electromechanotron сonverter based on a combined electric reciprocating generator” has not been given due attention. In this regard, a simulation model of the system “free-piston engine – electromechanotron сonverter based on an electric generator of reciprocating motion” was developed, which allows conducting research of this system in various operating modes when changing the parameters of the electrical and mechanical subsystems. A distinctive feature of the developed simulation model is the consideration of the features of simultaneous use in the magnetic system of an electric generator of reciprocating motion of transverse and longitudinal nonlinear changes in magnetic flows. As a result of the simulation model studies, it is shown that the combined electric generator of reciprocating motion allows for continuous conversion of mechanical energy of reciprocating motion into electricity over the entire operating cycle, as well as – to compensate for the mismatch of the forces of the electrical and mechanical subsystems of the system “free-piston engine – electromechanotron converter based on an electric generator of reciprocating motion”.

Powerful n-channel DMOS-transistor with drain-source breakdown voltage U_{ds br} value over 800 V and thresh-old voltage from 2 to 5 V was considered in this paper. One or more guard rings are formed on perimeter of such transistor for the breakdown voltage raising. The optimal guard rings construction was described and resistivity value of epitaxial film ρ_v was determined for obtaining required transistor U_{ds br} value. The regression model was built, with the help of which the most optimal construction variants of guard rings of investigated transistor and resistivity value of epitaxial film, were selected. It was established that the five-dimensional polynomial of second order using as regression model allowed choosing the optimal topological spaces values in the guard rings area and ρ_v value which made it possible to obtain required U_{ds br} values of the transistor. Experimental values of transistor drain-source breakdown voltage were 876 and 875 V, but calculated values (at identical parameters of definitional regression model) were 874 and 880 V, accordingly, that were errors of 0.23 % and 0.57 %, i. e. made model fits well with experimental data. It was established that ρ_v makes contribution to breakdown voltages values of the transistor that is more substantial than parameters of guard rings construction. This NDMOS-transistor was manufactured under production conditions of OJSC INTEGRAL” – “INTEGRAL” Holding Managing Company according to the technological route developed by the author. Such device is used in various electronic devices for energetics, in mobile phones, as part of high-voltage integrated circuits of AC/DC- and DC/DC-converters and high-voltage, high-stable LED-drivers.

At present, silicon photoelectronic multipliers with a low voltage, high sensitivity in the visible and near infrared spectral regions, and large amplification factors are often used to record optical radiation in a wide range of intensities of the visible and near infrared spectral regions. The purpose of this article is to determine the dependence of the type of amplitude distribution of pulses, created by silicon photoelectronic multipliers, on the intensity of the recorded optical radiation. As research objects, commercially available Ketek PM 3325 and ON Semi FC 30035 silicon photomultiplier tubes have been used, as well as multipliers from a pilot batch manufactured by OJSC “INTEGRAL” (Republic of Belarus). The paper studies the amplitude distribution of voltage pulses, formed on the load resistor of silicon photoelectronic multipliers by the photocurrent for various values of the energy exposure of optical pulses. The range of values of the energy exposure of optical pulses was determined at which the amplitude distributions of these pulses have pronounced peaks. It was found out that with increasing energy exposure of the optical pulse, part of the peaks disappears. It was established that all the dependencies of the average amplitude of such pulses on the magnitude of the energy exposure of the optical pulse for silicon photomultiplier tubes have a linear section. The performed experimental studies showed that an increase in the energy exposure of optical pulses results in an increase in the dispersion of the amplitude distribution of pulses. It was found that for a linear dependence of the energy exposure of the optical pulse on the optical pulse duration in the range from 50 ns to 1 μs, the studied silicon photoelectronic multipliers formed voltage pulses of 1 μs duration with the same rising and falling edges. In this case, the average amplitude of these pulses had a linear dependence on the duration of the optical pulse. The results can be used in design of photodetector devices for monitoring the level of ionization radiation for nuclear power plants, for quantum information systems and in optical communications for transmitting information with monitoring the presence of information leakage channels.

The article covers the possibilities of comprehensive use of identification technologies and Distributed Ledger Technology (DLT) for increasing the efficiency of electronic services provided through multi-purpose student cards. The main advantages and disadvantages of the existing intellectual document emission systems in the Belarusian education system are assessed, including: centralized (the “Student Card” project) and decentralized (the electronic student card) ones. The proposal to use the DLT-model for issuing multi-purpose electronic student cards combined with bank payment cards has been grounded. Such model makes it possible to implement new functional capabilities when providing electronic services and has a number of advantages over the existing systems of electronic student documents issuance. The article describes how Public Blockchain and Private Blockchain can be used to issue and control intellectual documents, to accelerate the development of the electronic services provided through Smart Contract, and how the Smart Contract technology can be used to promote fair competition among electronic services providers. The methodology of evaluating the electronic services provider rating basing on the weighting factor of “usefulness” or “being in demand” is proposed. The article provides information on the expected effects of the proposed DLT-model implementation, obtained through the comprehensive use of identification technologies and distributed ledger technology.

A technique of synthesis of a wireless digital communication network with package switching, providing transfer of video messages of real time scale between elements of multipurpose information-operating system in conditions of high failure rate of central elements, is considered. As conceptual model of a telecommunication network – the network of the mixed structure, including multipurpose devices, constructed on the basis of standards of a broadband radio access with switching of packages and two interconnected levels of network interaction of elements (local and main) is accepted. The technique of synthesis of a wireless network is based on the multilevel, combined adaptation of a telecommunication network in the conditions of refusals of central elements, which primary goal is rational change of parameters, functions of network elements in close interrelation with purposeful transformation of structure of telecommunication system subnetworks. The main objective of carrying out the combined adaptation of the network consists in achievement of necessary throughput of communication system depending on degree of failure rate of central elements. Properties of multilevel adaptation were investigated in the course of realization of the combined (structurally-parametrical) synthesis with use of the aggregate approach of modelling of difficult technical systems. Efficiency of the specified technique is proven by the results of the imitating experiment with use of the aggregate model of a wireless network of data transmission with switching of packages, obtained previously. The experimental data, received at natural research of networks of a broadband radio communication on the basis of standards 802.11 b/g/n, have shown, that time of processing of packages of a message essentially depends on use of existing ways of adaptation. In particular, application of effective algorithms of adaptation (both parametrical and structural) will allow to reduce the time of finding of details (packages) in broadband communication devices by several times and, thereby, to provide demanded throughput of the network functioning in the conditions of refusals of central elements.