The regularities of the influence of the pressing temperature in the roll compactors of halurgic fine-grained potassium chloride on the performance of the granulation process and the physical and mechanical properties of the granulate under the conditions of the Sylvinite Processing Plant of JSC “Belaruskali” are determined. It is shown that an increase in the pressing temperature from 120 °C to 142 °C significantly enhances the intensity of the processes of particles recrystallization and melt formation at the particles’ contact points in the zone of plastic deformation, which provides greater strength of interparticle contact bonds due to the formation of additional bonds of the crystallization type. At the same time, the particle size distribution of the granulate practically does not change. Only a slight decrease in the dynamic strength of the granulate was revealed as a result of a small increase in the number of cavities and cracks in the granules, which is not critical for obtaining a high-quality finished product. In general, an increase in the pressing temperature of halurgic fine-grained potassium chloride up to 140–145 °C enables to enhance the capacity of granulation plants up to 130 % without reconstruction of existing production lines while maintaining the high strength and granulometric characteristics of finished products. At the same time, the switch to higher pressing temperatures requires solving the problem of intensive salt caking on the working surfaces of the rolls of roll compactors based on the technical modernization of the existing compacting plants, taking into account the recommendations developed.

The study of vibration loading of the main elements of personal electric vehicles and the search for ways to reduce vibration characteristics was conducted. The issues of measuring vibration arising on a bicycle, which is driven by human muscle power and an electric drive, are considered. Measurements of vibration acceleration and frequency spectra in a certain area of motion were carried out using the “Octave-101VM” spectrum analyzer in three stages. At the first stage, the electric bike was driven by a pedal drive, at the second – by an electric drive, at the third – the pedals and the electric drive worked in parallel. As a result of the tests carried out, it was found that the greatest vibration occurred in the “Motor” mode during the use of an electric bicycle, the least vibration occurred when driving with the electric motor turned off. It was found that the electric drive increases the vibration level (at the same time, the electric bike does not exceed the maximum permissible values of vibration levels on all axes). In order to reduce the vibration arising from the electric motor on a personal electric vehicle, a 3D computer model has been developed and an airless wheel mover has been manufactured using this model on a 3D printer (a wheel for an electric scooter with internal damping has been manufactured). Bench tests have shown that the developed wheel, in comparison with a pneumatic tire, has a smaller (up to 45 %) contact spot. The results obtained can be used in the development of competitive products, in particular personal electric vehicles.

Stress state of the surface layer in the contact zone of mating teeth of cylindrical gears has been studied. It is established that stressed state of contact surfaces in the meshing pole of mating teeth is characterized not only by surface contact stresses, but also by deep equivalent stresses. It is shown that under contact loading the stressed state of surface layer is heterogeneous and changes with distance from the surface. Analysis and substantiation of calculation model for stressed state of diffusion layer in contact zone of mating teeth of surface-hardened gears are performed. Value of coefficient, which takes into account influence of normal stresses on efficiency of tangential ones, is specified. Reliability and validity of model of calculation of stressed condition of surface layer in contact zone of mating teeth of surface-hardened gears were estimated according to results of full-scale bench tests of the gears made of cemented steel 20ХГНР. The values of contact stresses in tooth meshing pole were corrected considering the load concentration across the width of cogged ring gear. Spalling depth of damaged teeth was determined by measuring impressions taken from the teeth of each examined gear with methacrylic resin. It is established that the nucleation zone of deep contact pitting for gears with 6.5 mm module is on the depth of occurrence of calculated maximum equivalent shear stresses. The consistency of the calculation results with the experimental data shows the validity of the calculated stress-strain model for involute gears.

This paper reviews the theoretical and experimental works concerning one of the most important parameters of wurtzite gallium nitride – thermal conductivity. Since the heat in gallium nitride is transported almost exclusively by phonons, its thermal conductivity has a temperature behavior typical of most nonmetallic crystals: the thermal conductivity increases proportionally to the third power of temperature at lower temperatures, reaches its maximum at approximately 1/20 of the Debye temperature and decreases proportionally to temperature at higher temperatures. It is shown that the thermal conductivity of gallium nitride (depending on fabrication process, crystallographic direction, concentration of impurity and other defects, isotopical purity) varies significantly, emphasizing the importance of determining this parameter for the samples that closely resemble those being used in specific applications. For isotopically pure undoped wurtzite gallium nitride, the thermal conductivity at room temperature has been estimated as high as 5.4 W/(cm·K). The maximum room temperature value measured for bulkshaped samples of single crystal gallium nitride has been 2.79 W/(cm·K).

The article presents the numerical simulation results on heat transfer and hydraulic losses of air-cooled exhaust-shaft apparatuses. Studies were made on air-cooled apparatuses in which four-row bundles of staggered finned tubes were placed. Numerical simulation used a gas dynamic solver Ansys Fluent. Menter’s shear stress transport κ-ω model was invited to close the Reynolds equations. The obtained numerical results allowed us to visualize air flow in the bundle and the exhaust shaft, as well as to establish an inhomogeneous distribution of velocities and temperatures. We found that the temperature distribution in the flow passing through the exhaust shaft depends on the height of the exhaust shaft. We also established that at small shaft heights in the wake behind a bundle because of the wake oscillatory motion, the dynamic and temperature inhomogeneous distributions take place, resulting in the cold air suction through the shaft from the environment. With an increase in the shaft height, the inhomogeneous temperature distribution moves upstream the air flow in the shaft and the inhomogeneous temperature distribution attenuates. We can say that maximum heat transfer at the same hydraulic losses is achieved when mounting a shaft with a height of H > 1.16 m. The results obtained can be used for the modernization of existing air-cooled apparatus, as well as for the design of new devices with an exhaust shaft.

The scientific basis for the design of noise suppressors for internal combustion engines with exhaust gas heat recovery, providing the release of gas flows with improved gas-dynamic and acoustic characteristics, is presented. The thermodynamic analysis of the processes of energy utilization of exhaust gases has been studied. Thermodynamic analysis showed that the utilization of exhaust gas heat leads to an increase in the coefficient of performance (COP) of the Otto cycle. An exergy analysis of heat exchange processes in the muffler was also carried out, and ways to increase its thermodynamic efficiency were determined. It has been established that a noise silencer with a heat exchanger-coil installed inside, from the position of the second law of thermodynamics, expressed by means of exergy analysis, is a more advanced thermodynamic system compared to a conventional silencer. A mathematical description of the recycling processes under conditions of external thermal exposure is given, while the nature of the influence of thermal exposure on changes in pressure, temperature and density is established. Based on the method of L.A. Vulis analytical equations for changes in pressure, temperature and density are obtained. Exhaust gas energy recovery processes contribute to a decrease in gas temperature, an increase in density, a decrease in flow velocity and a pressure drop, i.e. there is an effect (law of L.A. Vulis) of thermal stagnation of the gas flow, which causes a decrease in the noise level with less back pressure and an increase in engine efficiency.

The drying process of oilseeds in a suspended layer is investigated in order to increase productivity, reduce energy consumption and improve the quality of seeds for multipurpose use. To study the process of drying seeds of agricultural oilseeds, an experimental installation for drying seeds in a suspended layer has been developed, tested, optimized and implemented. The developed plant for drying seeds in a suspended layer is simple in design and easy to use, has high productivity. It also automates the process and has demonstrated a high level of operational safety during testing. To evaluate the effectiveness of the process of drying seeds in a suspended layer using the developed installation, three types of seeds of oilseed crops were selected: flax seeds, grapes and white sea buckthorn seeds. The results of the conducted studies of the drying process using the developed installation are: increasing the speed of the drying process; reducing the processing time; reducing energy consumption; reduction of processing costs; reduction of cost of processed products; improvement of the quality of processed products by increasing the degree of uniformity of drying and ensuring the preservation of the basic properties of seeds during heat treatment, mainly by reducing the degree of oxidation of vegetable fats in their components. Due to the rationalization of the drying process of oilseeds based on processing in a suspended layer, a number of tasks currently facing enterprises engaged in the primary processing of agricultural products have been solved. Using the results of the study will increase productivity, reduce energy consumption and processing costs, reduce the degree of oxidation of vegetable fats in the composition of seeds and improve their quality for subsequent use in the food industry, medicine, cosmetology, pharmaceuticals, etc.

A method for assessing the accuracy of source positioning using a new phantom for quality control procedures of applicators in brachytherapy is presented. A description is given of a phantom for performing measurements as part of quality control procedures for brachytherapy applicators, which are placed in the phantom in the form of a rod at a distance of 2–4 cm from the location of the ionization chamber. The air kerma strength was measured and the distance from the source to the ionization chamber was calculated. The measured values of the distances were compared with the values obtained by measuring the X-ray images of the applicator with a source located in it or radiopaque markers. The parameters recorded using the developed phantom are in good agreement with the parameters obtained using the X-ray machine installed in the procedural room (p > 0.05). The use of the proposed phantom will allow not only determination of the accuracy of the radiation source position in the applicator channel, but also verification of the irradiation plans for various types of applicators, including the use of shielding blocks.

This paper presents the results of computational studies of the amount of solid high-level and long-lived intermediate level radioactive waste (HLW and ILW-LL) generated during neutron activation of structural materials adjacent to the core of the VVER-1200 reactor of the Belarusian NPP, depending on the time after the final shutdown of the reactor. The assessment of the volumes of HLW and ILW-LL of activation origin, formed over 60 years of operation of the VVER-1200 reactor, was carried out on the basis of computational studies of the induced activity of structural and shielding materials using reactor and Monte Carlo program codes (SERPENT 2, TVS-M, DYN3D, MCU- PD). As a result of calculation studies, it was established that the masses and volumes of activated materials, according to the levels of pollution related to HLW and ILW‑LL, within 10 years after the final shutdown of the VVER-1200 reactor of the Belarusian NPP will be 273 tons and 43 m3 , respectively. In the interval of 30–70 years, the masses and volumes of activated materials of these categories of RW will amount to 262 t and 33 m3 , respectively. From 100 years to 200 years, the masses and volumes of activated materials of these categories of RW will be 118 t and 15 m3 , respectively. Within 10 years after the reactor shutdown, isotopes 55Fe (2.7 years), 60Co (5.27 years), 63Ni (96 years) will make the main contribution to the value of the integral specific activity of the materials of the structures of the fence, shaft, surfacing, reactor vessel, block of protective tubes (BPT), the space under the core, thermal insulation; after 10 years – 63Ni. The main contribution to the value of the integral specific activity of materials of absorbing elements (PEL) with Dy2TiO5 during the entire period of storage will be made by 63Ni.