The results of a study of the phase composition, surface morphology, grain size and mechanical properties of submicrostructures based on chromium and nickel before and after rapid thermal treatment (RTT) at temperatures from 200 to 550 °C are presented. Surface morphology and grain size were determined using atomic force microscopy. Mechanical properties were determined by nanoindentation. Rapid thermal treatment of nickel and chromium films significantly affects the change in phase composition, surface morphology, grain size and properties. The formation of silicides (according to the diffusion mechanism) and new phases occurs in the films: the CrSi₂ phase is formed at temperatures of 350 °C and above, the Ni₂Si phase at 300 °C, and the NiSi phase at 350 °C and above. When the phase composition changes, the grain size increases. In the RTT ranges from 200 to 300 °C and from 450 to 550 °C for chromium-based submicrostructures, the correlation between microhardness and grain size is carried out according to the Hall–Petch law – microhardness increases with decreasing grain size. For nickel-based submicrostructures, the Hall–Petch law is satisfied in the temperature range from 200 to 300 °C and from 500 to 550 °C. In the temperature range of 300–450 °C for chromium-based submicrostructures and 300–500 °C for nickel-based submicrostructures, microhardness decreases with decreasing grain size and vice versa, i.e. a “negative Hall– Petch effect” occurs. This effect is associated with the phase transitions Cr → CrSi₂ and Ni → Ni₂Si → NiSi, restructuring of submicrostructures due to the diffusion mechanism, morphological rearrangement of vacancy defects and annealing of point defects inside grains, as well as the corresponding reconstruction of grain boundaries. The considered submicrostructures based on chromium and nickel can be used in microelectronics for Schottky diodes, ohmic contacts and gates.

Based on the fact that the complexity of the product design affects the labor intensity of its manufacture and the efficiency of operation, the concept of product complexity is formulated by determining the number of levels of the design structure. It is proposed to describe the structure of the product design using a graph reflecting the connections between the elements of the product design, and to show their subordination using the design bases of each element and describe the number of levels and the number of elements at each level of the graph. It is shown that the structure of the design affects the construction of the route of the assembly technological process of the product. In this regard, it is proposed to supplement the initial data for designing the assembly technological process with a graph indicating the connection modules on its edges. This allows, in the presence of an element base of the means of technological support for the connection modules, determination of the expected labor intensity of the product assembly. 

The article presents the results of theoretical and experimental studies of electroplastic deformation by drawing (EPD) of electrical aluminum on an industrial multi-pass mill. The influence of a pulsed current with a density of ~ 10³ A/mm² and a duration of ~10^–4 s on the implementation of EPT in a deformation unit loaded above the yield limit, under conditions of excitation of the electronic subsystem of the metal, is considered, and the fundamental possibility of programmed control of deformation processes for modifying the physical and mechanical properties of technically important materials is shown. It was revealed that under conditions of electroplasticity, due to ponderomotive effects in the deformation zone, with the periodicity of current pulses at the front of their increase, ultrasonic vibration is created, causing additional mechanical stresses of the crystal lattice skeleton and actively influencing the kinetics of plastic deformation with improving the service characteristics of the material. The areas of technological application of EPV are drawing of ultra-fine, thin wire (up to ~ 1 mm in diameter), rolling of thin sheets, drawing and stamping of material. The installed technologies correspond to the most widespread production in the metalworking industry.

Numerical investigation of heat transfer is carried out in an air channel of the rectangular cross section (0.005 × 0.031) m with the length of 0.175 m. The lower surface of the channel is uniformly heated up to 343 K, and the air flow temperature at the channel entrance is 293 K. Two flow rates Q = 0.0010044 and 0.00209 m³/s are considered. The heat transfer between the channel surfaces and the cooling air flow enhances by vortex generators (VG) placed at a heated and an opposite surfaces. These generators are formed by two rectangular plates arranged vertically on the surface and at an angle of attack α = 15° to the flow. The plate height is h = 0.002 m and its length is 0.015 m. The VGs at the heated surface creates a pair of longitudinal vortexes that generates behind the plates a common flow to the surface while a pair of longitudinal vortexes at the upper surface creates the common flow away from it. Interaction of longitudinal vortices and secondary flows created by them with the main flow enhances mixing inside the channel and heat exchange with surfaces. Investigation was carried out by the RANS method at Re = 1300–2600 based on the VG height and the flow velocity at the channel entrance. It is shown that the thermal power of the channel with VG at the lower surface increases relative to that in the smooth walls channel by 17–23 % for the considered flow rates. If VG are placed at the both surfaces, the channel thermal power increases by 27–32 % depending on the flow rate.

The analysis of the operating features of closed-type electric heaters of the radiant tube type is performed. Based on the operating experience of the radiant tubes manufactured by “PromTermoSistema” LLC (Belarus), the key aspects affecting the durability of the heaters are shown. One of the main technical problems is the dense arrangement of heating elements (metal rods) in a small volume and the associated electrical breakdowns of electrically insulating ceramic inserts. Based on graph theory, a method is proposed for analyzing the commutation of heating elements with dense packing, which made it possible to find new rational commutation schemes. The method is based on constructing numbered graphs on the holes for heating rods in the ceramic element and finding the graph with the minimum weight. According to the meaning of constructing a graph, its weight is proportional to the maximum potential difference between the rods. The found commutation schemes reduce the maximum potential difference on ceramic insulators by 35–50 %, from 70 V to 35÷45 V, and the electric field strength from 10 kV/m to 5.0÷6.5 kV/m. This allows proportionally increasing the reliability and durability of heaters, reducing the probability of electrical breakdowns of ceramics.

Mathematical models of radiated, reflected and differential radio signals used in radio altimeters in the time and frequency domains based on the analytical Gabor method in quadrature form are presented. Symmetric and asymmetric types of linear frequency-modulated radio signals and limitations used in their analytical application, as well as signals using a sinusoidal type of modulating voltage, are considered. The time, frequency, correlation and zero counting methods of construction are given. Each of the methods corresponds to the same principle of construction. Detailed structures of radio altimeters are given, their advantages and disadvantages are considered, and recommendations for their use are given. 

The silicon p–n⁺ junction device-process modeling in both rectangular (Cartesian) and cylindrical coordinate systems was executed. In this semiconductor structure the p-region is the base and the n⁺-region performs the function of an emitter in an n–p–n-type bipolar transistor. The structure of the p–n⁺ junction explored in this work was obtained in accordance with the manufacturing process by two-dimensional modeling using the TSuprem4 program, which is part of the Synopsys software package. The process simulation allowed  determination of constructive-technological parameters of investigated p–n⁺ junction structure, which made it possible to carry out its device modeling in cylindrical and Cartesian coordinate systems using the Medici program, which is also part of the Synopsys software package. Direct and reverse branches of the p–n⁺ junction current-voltage characteristic were computed for modeling cases in these types of coordinate systems and, accordingly, a number of the junction structure electrophysical parameters were determined as a result of calculations performed by Medici. By comparing the data obtained by the method of device-process modeling it was found that the considered structure can be calculated in both types of coordinate systems with a high degree of accuracy, since the dispersion  of constructive-technological parameters defined by technological modeling in different coordinate systems was 2.6–7.4 %, and the dispersion of electrophysical parameters calculated by in device simulation was 0.09–8.64 %. The obtained research results were applied in the design of new electronic products based on one or more p–n junctions, in the development and optimization of its making process flows.

The paper demonstrates a methodology of a complex stability estimation for underground mining excavations located in salt rock masses. Various geological structures of the rock mass, as well as the most popular safety measures for underground excavations support such as ankers, expansion gaps and reinforced concrete are considered. The proposed methodology is based on a hybrid numerical-analytical method for the determination of the stress-strain state of geotechnical systems as well as on an original complex limit state criterion for rock masses. As the result of the study the main factors influencing the stability of excavations where highlighted and generalized. These factors are: mining depth, mechanical properties of rock mass, its geological structure and safety measures. The degree of the importance of each mentioned factor is established. A number of model problems are solved to prove the efficiency of the proposed method for complete and reliable estimation of rock mass state in the vicinity of underground excavations, as well as predicting the stability of geotechnical structures under various conditions.