Single-phase compositions in the MnSe–TmSe quasi-binary section have been synthesized by the method of reactions in the solid phase. The crystal structure of polycrystalline powders has been studied in CuK_α-radiation. It was found that the samples in the concentration range 0  x  0.7 have a cubic structure of the space group Fm m3 . An increase in the concentration of Tm cations in the Mn_1–xTm_xSe compositions leads to an increase in the unit cell parameter a from 0.547 nm for the Mn_0.975Tm_0.025Se compound to 0.566 nm for the Mn_0.3Tm_0.7Se composition. Thin layers of Mn_1–xTm_xSe solid solutions were synthesized by the flash method on optically transparent glass substrates. The film thicknesses are in the range of values from 0.8 to 3.2 µm. It has been established that Mn_1–xTm_xSe films also have the system NaCl, S.G.: Fm m3 . The composition of the Mn_1–xTm_xSe films corresponds to the chemical composition of the MnSe–TmSe charge powders. In the temperature range ~ 80–900 K, the va lues of the specific magnetization and magnetic susceptibility of the studied selenides were measured. The results obtained make it possible to determine the temperature regimes for the synthesis of new magnetic semiconductor substances, including those in the film state. The synthesized substances can be used in multifunctional microelectronic devices, as well as in the development of new materials capable of operating in wide temperature ranges and under the influence of external magnetic fields.

An effect of mechanical activation of graphite-like (hexagonal) boron nitride (hBN) on catalytic synthesis of nano- and micropowders of cubic boron nitride (cBN) under conditions of high pressures and temperatures is shown in the article. It has been suggested that nuclei of dense phases of boron nitride (cubic and wurtzite) are formed in the hBN structure during mechanical activation they serve as crystallization centers stimulating the formation of cBN crystals under subsequent thermobaric treatment. Additional chemical-thermal modification of hBN with aluminum as a catalyst (initiator) for the phase transformation of hBN into cBN leads to a significant increase in the content of cBN along with an increase in the synthesis pressure. Thus, the introduction of Al additives in the amount of 10 wt.% leads to an increase in the content of the cBN phase from 10–15 % under synthesis pressure of 2.5 GPa up to 90 % under pressure of 5.5 GPa. In this case, the grain size of cBN, estimated by scanning and atomic force microscopy, is mainly 200–400 nm and 40–120 nm for the samples synthesized under pressure of 2.5 and 5.5 GPa, respectively. The increase in the content of the initiator from 10 to 40 wt.% with an increase in isothermal holding time from 15 to 60 s in the studied range of pressures and temperatures leads to the formation of intergrowths of cBN grains in nano- and submicron sizes and individual cBN single crystals of a cubic habit with a grain size of 1–4 µm, as well as polycrystalline cBN particles from 10 to 50 µm. In this case, the maximum size distribution of cBN micropowders in the range up to 50 µm falls on particles up to 5 µm (~ 70 %). In the submicron grain size range the maximum yield (~ 50 %) is marked for cBN particles 0.5–0.7 µm in size. The obtained powders can be used to make abrasive and cutting tools.

The influence of the regimes of plastic deformation of steel – copper alloy pseudo-alloys obtained by infiltration on their structure, mechanical properties and anisotropy of properties is investigated. It has been established that hot forging of pseudo-alloys at a temperature of 700–950 °C provides an increase in strength by 1.5–3 times, impact strength by 1.5–2.5 times, plasticity by 1.5–2 %, and at 1100–1150 °С (above the melting point of copper) – leads to cracking of the material. It is shown that the properties of pseudo-alloys based on steel alloyed with chromium are lower than those based on steel alloyed with nickel, which is associated with the formation of chromium oxides due to its increased affinity for oxygen. The formation of macro-texture in pseudo-alloys after hot stamping has been established, which leads to secondary anisotropy of properties, the level of which is determined by the degree of deformation and temperature, but does not exceed 15–20 %. The deformation curve of the pseudo-alloy during hot forging was constructed, which revealed the optimum temperature (700–900 °С) and the limiting degree of deformation (65 %) depending on the composition of the pseudo-alloy. With an increase in the degree of deformation, microcracks form at the interface between the iron and copper phases, which in turn leads to a decrease in strength, ductility, as well as a 1.5–2-fold decrease in the impact strength of pseudo-alloys with a copper phase content of 15 % and destruction of pseudo-alloys with a 25 % copper content phases, in which the length of interphase iron-copper boundaries is much greater. The achieved mechanical properties of hot-forged steel-copper alloy pseudo-alloys make it possible to use them for parts of heavily loaded friction units, as well as parts for structural purposes. 

The paper considers a technique for assessing mechanical stresses in coatings by the magnetic ponderomotive method, based on the use of the magnitude of the magnet breakaway force and its relation to the magnetic characteristics of nickel (magnetic susceptibility), which change under the action of internal stresses. It is shown that the existing mechanical stress measuring equipment using X-ray, magnetic or ultrasonic methods have specimen size limitations or have low measurement locality. At the same time, a magnetic ponderomotive method for controlling mechanical stresses is presented, which does not have the indicated disadvantages. The change in the magnetic breakaway force on the thickness, applied and residual stresses caused by elastic and plastic deformations in the sample is theoretically substantiated. It is shown that the presence of residual stresses in the sample changes the nature of the dependence of the magnet breakaway force on the applied stresses. A calculation algorithm has been developed that allows measuring the magnet breakaway force to obtain the ratio between the applied and residual stresses. It is shown that the ratio between residual and applied stresses can be used to assess the degree of proximity to the critical stresses levels that lead to failure. Calibration surfaces are constructed for the dependence of applied stresses on magnetic separation force and thickness, corresponding to elastic-plastic deformation, as well as leveled calibration surfaces, corresponding to elastic deformation in the presence of residual stresses in the material. Experiments have been carried out on real samples and coatings, that determine the degree of approximation of internal stresses in the material to critical levels that may lead to destruction. It is shown that when comparing the readings of calibrated gauges with a certified tool, the largest deviation occurs at low stress values due to the inverse dependence of the breakaway force on the stress level.

Studied the possibility to extend the life of the Production Unit no. 3 mine of JSC “Belaruskali” through the additional extraction of sylvinite ore reserves left in the previously mined panels of the mine field of the 3rd potash level. It was determined, that during the period from 1971 to 1980 a considerable part of the southern direction of the mine field on the area of more than 5,3 million m2 was mined by the roadways on the layers 2, 2–3, 3 without the mining of the 4th sylvinite layer. The volume of the leftover reserves of minerals in the mined panels makes more than 22 million tons. There is direct access to these panels from the main southern gates. As a study result of geological structure of the mined panels it was determined that under the influence of rock pressure the undermined sylvinite layer no. 4 took the form of a wave-shaped seam with the capacity of about 1 meter which rests on compressed inter-chamber pillars and on compressed rocks of layers 2, 2–3, 3 of destroyed inter-roadway pillars, which fills the space of the roadways. Such geological structure of the seam enables to extract minerals using the technology of selective layer mining by successive top and bottom faces. As a study result of the stability of the mine workings performed along the roadways and inter-chamber pillars under conditions of different roof positioning, it was determined that during the preparation of the faces the most advantageous locations for development workings are the areas previously mined by the room and pillar mining system. In this case, the highest stability of mine workings located in the stopes of the room and pillar mining system will be provided by their roofing location with cut of 0.15 m of the 4th sylvinite layer. When this occurs, their predicted life without repair, even without the use of special protection methods, would be between 3.5 and 8 years. Based on the results of the study, a conclusion was made on the technical possibility and economic feasibility of additional extraction of sylvinite ore reserves left in the western panels of the southern direction of the mine field of the 3rd potash level of the Production Unit no. 3 mine, finished over 40 years ago by the room and pillar mining system using selective layer mining technology by the longwall faces. With minimal capital, organizational and technical expenditures, the extraction of these reserves will allow the company to produce additionally 5.5 million tons of potash fertilizers.

The results of processing experimental data on heat treatment in drying processes of thin thermal insulation materials are presented. As a result of processing the experimental data by generalized complex variables, formulas for determining the heat flux density, average integral temperatures, the intensity of moisture evaporation, and the duration of the heat treatment process of materials were obtained. Based on the elements of the thermal regular regime theory, formulas for determining the rate of heating of the wet body and the rate of loss of moisture content have been established by processing experimental data using the least squares method. The conditions of the drying process in the regular mode are considered. Processing experimental data with generalized complex variables allows you to move from one coordinate system to another, from one variable to another, without performing additional time-consuming experiments. Based on the equation of drying kinetics and the generalized drying curve, the relationship between the dimensionless heat flux and the relative drying rate is given. For the single-zone method of calculating the drying rate curve, an approximate relationship for determining the relative drying rate is given. The relationship between material surface temperature and the relative drying rate in the heat treatment processes of ceramic tiles, asbestos sheets, wool felts was established. All of the above formulas were used to check the reliability of the obtained dependencies, as well as to compare the calculated values of the main parameters of the drying kinetics with the experiment.

The results of an experimental study of the thermal decomposition of natural dolomite, carried out on laboratory equipment at constant temperatures of 650 °C, 700, 750, 800 and 850 °C, are discussed. Particles of Belarusian dolomite weighing 0.58 g, 0.88, 2.3, 2.7, 7.6 and 16.3 g were used as the test samples. An integral equation describing the kinetics of thermal decomposition of natural dolomites of Belarus is presented. It is shown that the reaction rate of thermal decomposition of dolomite depends not only on the temperature regime in the reaction zone, but is also largely determined by the mass of the samples under study. It has been established that the rate constant of thermal decomposition of dolomite in the studied range of sample masses can be determined by the empirical expression identified in the course of this study. The rate constants of thermal decomposition of dolomite particles of various masses have been determined. The values of the rate constants obtained empirically and those calculated taking into account the mass of the samples are compared. It is noted that the developed model is physically justified, and the dependence proposed in the work can be incorporated into existing engineering methods for calculating generator gas purification systems using dolomite as a catalyst and sorbent.

The results of the study of the values of the reflection coefficients and the effective scattering surface of the developed design of the electromagnetic radiation screen in the frequency range of 2…12 GHz are considered. The structure consists of a layer of moisture-containing pseudo-oval scattering elements with linear dimensions of 1…4, 1…2 and 10…20 mm, which is placed between two layers of polyurethane sealing mastic. The use of pseudo-oval elements with linear dimensions of 1…4 mm containing solutions made on the basis of a 20 % solution in the developed electromagnetic radiation screen design allows reducing the values of the reflection coefficients of electromagnetic radiation at frequencies 4.2…6.5 and 1.0…4.1, 8.0…12.0 GHz. The formation of a screen design based on elements with linear dimensions of 1…2 and 10…20 mm, impregnated with a 20 % sodium chloride solution, leads to a decrease in the values of reflection coefficients in the frequency range of 2…12 GHz. It is established that the values of the effective scattering surface of ground objects in case of placing or fixing of the specified design variant of the electromagnetic radiation screen on their surface are 0.6…24.0 m² in the frequency range of 2…12 GHz. This makes it significantly difficult to obtain reliable information about the location and characteristics of ground objects in the frequency range under consideration.

A study was made of the characteristics of photodetectors for fiber-optic communication lines using quantum cryptographic systems – germanium avalanche photodiodes operating in the photon counting mode. In particular, it was established at what highest temperature the implementation of the photon counting mode is possible, and the influence of temperature and overvoltage on the sensitivity of photodiodes is also considered. An experimental setup has been developed for the research. It has been determined that the highest ambient temperature at which LFD-2 germanium avalanche photodiodes operate in the photon counting mode is 243 K. It has also been found that the highest sensitivity of germanium avalanche photodiodes corresponds to the optical radiation wavelength range of 1310÷1490 nm. Lowering the temperature leads to an increase in the sensitivity of germanium avalanche photodiodes. It was found that the dependence of the signal-to-noise ratio on overvoltage has a maximum corresponding to overvoltage ΔU = 0.1 V. Lowering the temperature led to an increase in sensitivity and signal-to-noise ratio. Since there was no shift in the maximum dependence of the signal-to-noise ratio on the overvoltage, it was therefore concluded that when the avalanche photodiode operates in the photon counting mode, in order to ensure maximum sensitivity, it is necessary to select the overvoltage corresponding to the maximum signal-to-noise ratio. The results obtained can be used in quantum cryptographic systems, technical means of protecting information transmitted over fiber-optic communication lines, and for the metrology of single-photon radiation sources.

The article is devoted to obtaining equivalent forms of writing of processing algorithms for the operation of adaptive antenna arrays, considering algorithms as varieties of some generalized LMS algorithm. This will facilitate a comparative analysis of the algorithms’ characteristics. The following algorithms of operation are considered: LMS, NLMS, LMS-Newton, SMI, RLS. The article contains the initial operation algorithms of adaptive antenna arrays, conclusions of equivalent processing algorithms and an equivalent block diagram of the generalized LMS algorithm. Equivalent forms of writing the operation algorithms of adaptive antenna arrays and their parameters are also presented in tabular form. Of particular interest is the equivalent operation algorithm in the case of the SMI algorithm, which differs most from the LMS algorithm. Equivalent algorithms differ only by the scalar convergence coefficient and the matrix normalizing factor. For LMS-Newton, SMI, and RLS algorithms, the matrix normalizing factor is the same, it is determined by inverting the estimation of the correlation matrix of input signals and reduces the dependence of the characteristics of the algorithms on the parameters of the correlation matrix. The scalar convergence coefficient of equivalent algorithms in the case of SMI and RLS algorithms depends on the iteration number and tends to zero for the SMI algorithm and to some non-zero value for the RLS algorithm. The dependence of the convergence coefficient on the iteration number makes it possible to optimize the characteristics of the algorithms at the transition stage. The tendency of the convergence coefficient to zero in the case of the SMI algorithm makes it effective only for stationary input signals. The non-zero steady-state value of the convergence coefficient in the case of the RLS algorithm allows its effective use in a non-stationary environment.

The effectiveness of the use of modern technologies and methods of radiation treatment depends on the means of quality control of the operational parameters of the radiotherapy equipment. The development of technical means for verification of the radiation therapy plan, allowing accurate assessment of the three-dimensional dose distribution in the target, is a priority task when introducing innovative methods of radiation treatment. The aim of the work is to develop tools for assessing the three-dimensional dose distribution of radiation therapy plans with intensity modulation using the magnitude of the absolute radiation dose. The authors analyzed the existing technical means and methods for verifying radiation therapy plans on medical linear electron accelerators, and also identified their shortcomings. It is shown that these techniques for verifying the three-dimensional dose distribution do not give an accurate idea of the absolute values of the radiation dose in the target. A system and a method are proposed that allows improving the accuracy of the verification of the radiation therapy plan by using the obtained cross-calibration coefficient determined taking into account the value of the radiation output of the medical linear accelerator immediately at the time of the implementation of both this procedure and the radiation therapy session, as well as a method for verifying the plan radiation therapy with their use.

The expediency of using Weather Research and Forecasting (WRF) numerical weather forecast model as a source of meteorological data during modeling of radioactive substances transfer in the atmosphere is considered, WRF technical details are briefly described. As the reference emergency scenario, the scenario of the maximum design accident hypothetically occurring at Belarusian Nuclear Power Plant (BelNPP) 12 UTC 21.03.2021 was chosen. Four numerical experiments with Global Forecast System (GFS) and WRF meteorological data and RIMPUFF and LASAT atmospheric diffusion models were performed in JRODOS Decision Support Systems (DSS). For each experiment, maps of underlying surface potential radioactive contamination of I₁₃₁ were created. The potential contamination of the underlying surface I₁₃₁ from 5 to 100 km from the BelNPP was assessed. The dependency graph of the maximum underlying surface contamination with I₁₃₁ on the distance from the BelNPP was plotted based on the experiments results. The obtained results indicate the prospects of using the WRF meteorological model in the DSS at various stages of the emergency situations development at the BelNPP.