In the work monolithic structures of yttrium iron garnet (YIG, Y₃Fe₅O₁₂) with a thickness of about 2 μm were obtained on ferroelectric ceramic substrates based on PbZr_0.45Ti_0.55O₃ (PZT) and Ba_0.4Sr_0.6TiO₃ (BST). The Y₃Fe5O₁₂ layer was deposited by ion beam sputtering deposition on substrates 400 μm thick by sputtering a polycrystalline Y₃Fe₅O₁₂ target with with argon ions. The heterostructures were crystallized by annealing in air at a temperature of 820 °C for 5 min. The results of the characteristic X-ray radiation method showed that the elemental composition of the monolithic heterostructure corresponds to the specified one. During X-ray studies, it was found that the YIG crystallization process is completed and the resulting structure is single-phase. The results of magnetic and ferromagnetic resonance studies indicate the possibility of using the obtained heterostructures in logic circuits based on spin waves with low scattering, in memory elements, as well as in electrically controlled microwave devices.

A new technology for manufacturing microwave electromagnetic radiation (EMR) absorbers characterized by a geometrically inhomogeneous surface is presented. The novelty of the presented technology lies in the use of radiotransparent polymer forms with hemispherical depressions of the same volume, which are the component for the formation of the surface layer of absorbers. The technology consists in filling these molds with a mixture of powdered activated (birch) charcoal and the binder in the liquid phase and further drying it in the forms. Compared with analogues, the developed technology is characterized by low complexity of reproduction. Most of the time required to implement the presented technology is associated with the drying process of a mixture of powdered activated birch charcoal and a binder. The experimentally established patterns of changes in the values of electromagnetic radiation reflection and absorption coefficients in the frequency range 1.0–28.0 GHz of the absorbers manufactured in accordance with the presented technology are provided, depending on the type of binder contained in them (polyvinyl acetate aqueous solution, gypsum aqueous solution, polyurethane mastic). It was determined that the most effective of the EMR absorbers studied in the course of establishing the indicated patterns are those ones that contain an aqueous solution of polyvinyl acetate. Electromagnetic radiation absorption coefficient values in the frequency range 1.0–28.0 GHz of such absorbers vary from 0.75 to 0.99. In addition, the mass per unit area of such absorbers is 1.5–2.0 times less than the mass per unit area of absorbers containing an gypsum aqueous solution or polyurethane mastic. Microwave EMR absorbers manufactured using the presented technology are characterized by higher mechanical strength, as well as lower cost compared to analogues and are recommended for use in the creation of anechoic chambers.

Due to the customization of production, it becomes especially important to test the design of the product for manufacturability at all stages of its creation. A method is proposed to improve the manufacturability of the product design at the stage of developing the working documentation of the product, based on its evaluation by summing the coefficients of manufacturability. The method consists in constructing a regression series of product design characteristics according to the degree of reduction of their impact on the complexity of the design and establishing the sequence of its improvement. It is recommended to improve manufacturability and reduce the labor intensity of manufacturing a product, to pay attention from the beginning to methods for achieving accuracy during assembly, as well as the use of the maximum number of purchased parts in assemblies; then on the repeatability of the types of connections of parts in the design, reducing the number of types and laboriousness of making connections, and finally on the repeatability of parts in the overall design, the maximum use of borrowed parts. It is shown that the typification of processes and the unification of structures can be effectively dealt with at the level of large associations (holdings, concerns) and especially industries.

The results of calculation studies of the amount of solid high-level, intermediate-level, low-level, very lowlevel radioactive waste (HLW, ILW, LLW, VLLW, respectively) generated during neutron activation of structural materials adjacent to the core of the VVER-1200 reactor plant, depending on the time after the final stopping it. An assessment of the volumes of radioactive waste (RAW) of activation origin generated over 60 years of operation of a VVER-1200 type reactor was carried out on the basis of computational studies of the induced activity of structural and protective materials using reactor and Monte Carlo program codes (SERPENT 2, TVS-M, DYN3D , MCU-PD). Specific activities for each isotope, total specific activities and activities, masses and volumes of activated structural and protective reactor materials for various categories of radioactive waste were calculated after the specified period of operation of VVER-1200 and over time after the final shutdown of the reactor. The obtained dependences of changes in the masses and volumes of activated materials over time after the final shutdown of the reactor make it possible to determine these parameters of materials separately for each category of radioactive waste and in total at any point in time. Thus, the masses of activated materials related to radioactive waste will decrease by 264 tons (from 713 to 449 tons) over 200 years of aging, and the volumes will decrease by 74.3 m³ (from 169 to 94.7 m³). Forecast quantitative data on the volumes and mass of activated reactor structures, depending on the duration of their exposure after the final shutdown of the power unit, will make it possible to develop technical proposals, forecast plans and schedules for organizing a radioactive waste management system during the decommissioning of the VVER-1200 reactor plant, as well as possible technological and design solutions for the disposal system for these radioactive waste.

We present the results of experimental studies of electron content in the ionosphere over the territory of the Republic of Belarus based on data from global navigation satellite systems. The results of measurements of the precise positioning system of the Republic of Belarus and navigation data of GPS satellites in RINEX format were used as input data. Expressions for calculation of the total electron content using the two-frequency method and a combination of measurements by phase and code delays are given. Algorithms for eliminating cycle slip and determining differential code biases are used. Examples of calculating the vertical electron content over the Republic of Belarus at different moments of time are demonstrated. The obtained results are reasonable to use in monitoring of the ionosphere in order to provide reliable operation of radio systems, detection of ionospheric anomalies of natural and artificial origin, as well as forecasting of natural phenomena on their basis.

Based on the analysis of the literature on the possibility of using neural networks to create new materials with high functional properties, the article considers a solution to the problem of determining the operational stability of polymeric composite materials by creating physical and chemically sound mathematical prediction models. Epoxy resins of the UP-637 and EA brands with an isophorone diamine hardener were chosen as the matrix of the model composite material, and oligobutadiene rubber of the SKN-10 KTR brand was chosen as the modifier. It justifies directions of work necessary for development of new materials creation methodology with optimal characteristics, building a model for changing the properties of materials at variation of composition and implementation of full-scale mathematical modeling of physical and chemical processes of polymer composite materials aging at changing level and time of climatic factors influence. Verification of the obtained dependence of service characteristics on the composition of the material and the level of influencing climatic factors was carried out on the basis of data from full-scale tests in a temperate climate. The proposed methodology for modelling the properties of polymer composite materials will reduce the development time of new materials and allow creation of polymer composites based on epoxy resin containing fillers of various natures (carbon, mineral and polymer) with high performance parameters.

Studies have been carried out to determine the main parameters characterizing the quality of cement compounds: ¹³⁷Cs leaching rate and mechanical strength. As sorption additives, aluminosilicate sorbents were used, obtained from clay-salt slimes of JSC “Belaruskali” as a result of water and acid-water treatment to increase the content of the clay mineral illite, which is the main component in the composition of aluminosilicate sorbents. Model aqueous solutions of ¹³⁷Cs were used as liquid radioactive waste, including those with a NaNO₃ content of 150 g/dm . It has been established that the use of aluminosilicate sorbents makes it possible to reduce the rate of ¹³⁷Cs leaching from cement compounds, which indicates a higher degree of ¹³⁷Cs fixation in the matrix material compared to samples of cement compounds without sorption additives. The efficiency of the aluminosilicate sorbent for ¹³⁷Cs immobilization during cementation of a model solution of liquid radioactive waste is 3 times higher than the well-known and widely used sorption additive (bentonite clay from the 10th Khutor deposit, Khakassia, Russia). Determination of the mechanical strength of samples of cement compounds with the addition of 5–15 % aluminosilicate sorbents showed that this indicator is 8–9 times higher than the standard value (4.9 MPa). The optimal dose of a sorption additive is 5–10 wt.% of the weight of Portland cement, which does not cause a significant decrease in the strength of the cement compound compared to a compound without the use of an additive and, at the same time, will provide a high level of ¹³⁷Cs immobilization. The obtained research results indicate the prospects of using the developed aluminosilicate sorbents as a sorption additive for ¹³⁷Cs immobilization when handling liquid radioactive waste.