The results of an experiment on the study of the crystal and magnetic structures of substitutional solid solutions of the Ni_0.90M_0.10MnSb (M = Ti, V, Cr) systems using thermal neutron diffraction in the temperature range ~ 3–300 K are presented. It is found that all the studied compositions have ferromagnetic ordering along the c axis. In the spectra of Ni_0.90V_0.10MnSb and Ni_0.90Cr_0.10MnSb solid solutions, a reflection appears in the region 2Θ = 28.6°, which indicates the formation of antiferromagnetic ordering. It has been found that this reflection disappears at a temperature T = 75 K in Ni_0.90V_0.10MnSb, while it is observed in the spectrum of Ni_0.90Cr_0.10MnSb over the entire temperature range under study. Within the framework of density functional theory (DFT), an ab initio calculation of the crystal structure and magnetic moments for Ni_1–xM_xMnSb (M = Ti, V, Cr; x = 0; 0.125; 0.250) was carried out. It has been established that titanium, vanadium, and chromium ions participate in electron transfer only with Mn and Sb ions. The DFT results predict the existence of magnetic moments for Ti, V, and Cr ions. It was found that the spins of Ti, V, and Cr ions are antiferromagnetically coupled with the spins of Mn and Ni ions. The results obtained are of interest for the development of new concepts and models of structural design, which makes it possible to synthesize fundamentally new functional materials with already specified physical properties.

The results of theoretical and experimental substantiation of the technique developed by the authors for the manufacture of heterogeneous (two- or three-layer) radio absorbing composite materials based on powdered charcoals are presented. The technique is based on layer-by-layer pouring of mixtures of a gypsum binder and powdered charcoal (non-activated birch, activated birch, activated coconut) into molds in the order in which the outer (relative to the electromagnetic radiation propagation front) layer of the composite material is characterized by the lowest wave resistance, and the inner layer is characterized by the highest wave resistance. The specified order is determined by the results of the theoretical substantiation of the developed technique. In the course of its experimental substantiation, regularities for changing the electromagnetic radiation reflection and transmission coefficients values of the manufactured materials depending on the value of the radiation frequency in the range of 0.7–17.0 GHz have been established. Based on the established regularities, it was stated that the minimum value of the electromagnetic radiation reflection coefficient of the two-layer materials manufactured according to the developed and substantiated technique (thickness ~ 5.0 mm) is –12.0 ± 1.0 dB and corresponds to electromagnetic radiation frequencies of 0.8 and 2.6 GHz (it’s provided, when such materials are fixed on metal substrates). The minimum value of the electromagnetic radiation reflection coefficient of the three-layer materials (thickness ~ 10.0 mm) under the specified condition is also –12.0 ± 1.0 dB and corresponds to electromagnetic radiation frequencies of 4.5 and 6.0 GHz. The electromagnetic radiation transmission coefficient values of such materials decrease with an average step of 4.0 dB as the frequency of the radiation increases by 1.0 GHz in the range of 2.0–10.0 GHz and increase with a similar step as the frequency increases by 1.0 GHz in the range of 10.0–17.0 GHz. The minimum value is –30.0 ± 2.0 dB. The materials manufactured according to the developed and substantiated technique seem to be promising for ensuring the protection of electronic devices from the effects of electromagnetic interference (both active and passive types).

The application of empirical, phenomenological deformation and energy theories of metal fracture in relation to the process of cross-wedge rolling is considered. A distinctive feature of cross-wedge rolling in comparison with other metal pressure treatment processes is the complex stress-strain state in the deformation focus and the possibility of opening the axial cavity. The existing empirical criteria of destruction are given. The scheme of a new calibration test based on crosswedge rolling and the fracture criterion proposed by Zbigniew Pater are considered. It is shown that the Zbigniew Pater’s empirical criterion for the destruction of Zbigniew Pater provides a correct determination of the moment of opening the cavity during cross-wedge rolling. The improved phenomenological deformation theory is based on the theory of fracture developed by V. L. Kolmogorov. It is proposed to evaluate the plasticity of the metal depending on the stress state in the form of two independent invariants of the stress tensor: the average stress and the parameter of the third invariant of the stress tensor. The dependence of the limit value of accumulated deformation, at which destruction occurs, on the stress state is constructed in the form of a plasticity surface. The phenomenological deformation criterion of metal destruction during plastic deformations allows us to determine the moment of opening the cavity during cross-wedge rolling and the plasticity resource of the metal.

The paper discusses the results of an experimental study of the thermal decomposition of pyrolytic wood tar in a homogeneous process, as well as in the presence of a number of mineral substances: potassium sulfate, magnesium sulfate, monopotassium phosphate and the mineral residue of the production of potassium salts. The experiments were carried out on a laboratory setup under isothermal conditions at temperatures of 300, 350, and 400 °C by two methods providing two-phase and three-phase contact with the catalyst, respectively. It has been established that the rate of decomposition of pyrolysis tar under the studied conditions obeys the laws described by the Avrami–Erofeev equation with a variable exponent n. The area of change of this indicator in various experiments includes values from 0.415 to 1.238. The mean n value calculated for all study options was 0.694 (95 % CI 0.605 to 0.783), and the median value was 0.639. It has been found that the decomposition rate of the pyrolysis tar increases when MOX particles, potassium sulfate, and magnesium sulfate are introduced into the reaction zone. No effect of monopotassium phosphate on the rate of decomposition of the pyrolysis tar was not found. It is shown that in the case of tailings of potassium salts production an increase in the rate of decomposition of pyrolysis tar is due to the catalytic effect of this substance. The most likely reason for the positive effect of potassium sulfate, as well as magnesium sulfate on the rate of decomposition of pyrolysis tar, is apparently also the catalytic effect of these substances. The Arrhenius parameters of the homogeneous process of thermal decomposition of the pyrolysis tar and the decomposition process in the presence of tailings of potassium salts production, as well as potassium and magnesium sulfates, were determined. According to the data obtained, the activation energy of the homogeneous process was 29.6 kJ/mol, and the pre-exponential factor was 3.15·10¹ min^–1, respectively. The Arrhenius parameters of the decomposition of pyrolysis tar in the presence of tailings of potassium salts production, according to the data of the performed studies, were 23.0 kJ/mol and 1.82·10¹ min^–1. The paper also determined the Arrhenius parameters of the decomposition of pyrolysis tar in the presence of K₂SO₄ and MgSO₄. According to estimates, the activation energy in the presence of these substances was about 50–60 kJ/mol. The research results presented in the article can be used in the design of heat generating equipment, which includes a system for cleaning products of thermochemical conversion of vegetable raw materials.

A method for calculating drying kinetics based on A. V. Lyikov’s kinetics equation and drying rate curves for the drying process of natural leather is presented. Methods of approximating velocity curves to determine the drying time are considered. An equation for calculating the drying time of natural leather with a variable drying factor is presented. Based on the processing of experimental data on drying of natural leathers, equations for calculating heat flux densities, intensity of moisture evaporation and material temperature in the period of falling drying rate are presented. Based on the approximation of drying speed curves for natural leathers, the equations for calculating the drying time by the methods of A. V. Lyikov, V. V. Krasnikov, and N. S. Mikheeva are considered. The dependence of the relative drying rate on the dimensionless moisture content is presented. The reliability of the experimental equations was checked and the calculated values of the drying time and material temperature were compared with the experiment. The proposed approximate methods of calculating the skin drying speed curve make it possible to evaluate the nature of the drying process of a particular material by individual zones of the second period and when changing the drying mode. They also make possible determination of the most important parameters of drying kinetics and reduction of the number of experiments.

The results of experimental studies of the influence of gamma radiation Co60 on the basic parameters of silicon epitaxial-planar p-channel MOSFET transistors under different electrical modes are presented. Transistors were manufactured according to radiation-resistant DMOS technology with design standards of 1.4 μm. As a result of transistor studies, it was established that the values of all basic parameters after the radiation dose D = 10⁶ rads (SiO₂) in active electrical irradiation modes remained within the limits of the performance criteria; the parameter, most sensitive to influence of a dose of irradiation by gamma-quanta is the threshold voltage; in the passive electrical irradiation mode the transistor’s radiations resistance in all parameters corresponds to a dose of 2,8·10⁶ rads (SiO₂). A sufficiently high radiation resistance of the studied p-channel MOSFETs makes it possible to recommend them for use in aviation and space equipment. The different degrees of radiation degradation of the studied parameters during irradiation are due to their dependence either on the effects of ionization in the layers of sub-gate and insulating dielectrics, or structural damage in the bulk silicon of the transistor active regions. The high radiation resistance of the studied p-channel MOSFETs allows recommending them for use in aviation and space equipment.

The problem of object guidance to the target point using two time difference of arrival (TDoA) measurements obtained from three navigation positions is considered. A general equation that describes a kinematic trajectory of the object along the line of intersection of two object position hyperboloids corresponding to the two TDoA measurements is obtained. It has been found out that the kinematic trajectory of the object lies in a plane perpendicular to the plane of three navigation positions. This kinematic trajectory can be described by the conic equation in the general case, and in the range of position parameters used in practice this equation yields a hyperbola. A method of elimination of object spatial cross-coupled link between control system channels, consisting in a special projection of accelerations of the object during their transformation from the measuring coordinate system to the wind coordinate system is described. This made it possible to implement object control in TDoA navigation system with three navigation positions only using two identical expressions of the kinematic link obtained for a planar case without full spatial equation for kinematic link of the object’s motion and TDoA information. A computer simulation of the object guidance to a target point in space using two TDoA measurements was performed to check the accordance of the acceleration design expressions, which produced a positive results of viewed method. The approach described in the article makes it possible to implement object guidance using TDoA navigation system if available only three of four required navigation positions.

Using the J-RODOS and RECASS-EXPRESS software packages, modeling of the radiological and radiation-ecological consequences of a severe beyond design basis accident at the power unit of the Belarusian NPP with a VVER-1200 reactor was carried out. The simulation results showed that if radionuclides were released from the reactor containment at the level of 2.15·10¹⁵ Bq, the maximum values of the fallout from the atmosphere to the surface 1 day after the accident will be 2.98∙10⁵ Bq/m² for I-131 (J-RODOS) and 7∙10⁵ Bq/m² (RECASS-EXPRESS), and for Cs-137 − 1.11∙10⁴ Bq/m² and 1.3∙10⁵ Bq/m², respectively. The difference in the values of the radionuclide fallout, modeled by these software packages, increases with the distance from the release source and at a distance of more than 10 km reaches 1 order of magnitude. The predicted values of the equivalent thyroid dose for adults and children for the first 7 days after the accident, obtained using J-RODOS calculations, are 3–4 times higher than using RECASS-EXPRESS software product. At a distance of 3–5 km from the NPP site, doses ranged from 3.7 to 14.8 mSv for adults and 16.2 to 32.5 mSv for children. The values of the total effective dose with the J-RODOS simulation are 2 times higher than those with RECASS-EXPRESS at a distance of 3 km from the site (0.60 and 0.32 mSv, respectively) and 1.5 times higher at a distance of 5 km from the site (0.30 and 0.21 mSv respectively). As the distance from the NPP increases, the convergence in the obtained evaluation results of total effective dose increases. None of the obtained prediction results exceeds the established emergency response criteria and do not indicate the need for protective measures for the public.