There are analyzed creation and development of magnetic nanomaterials and nanostructures, films with a columnar type of crystal structure, multilayer film structures, nanocomposites, granular alloys and nanowires. The methodics of obtaining, structure, magnetic and magnetoresistive properties of three types of nanowires – multilayered and granular ones and the ones of spin-valve type are discussed. It is shown that multilayer film coatings with very thin (< 1 nm) alternating magnetic and nonmagnetic layers behave like films of granular alloys. It is emphasized that the films of granular Cu–Co alloys were first obtained at the Scientific and Practical Materials Research Center of the National Academy of Sciences of Belarus by the method of electrolytic deposition without subsequent annealing, as is the case with other methods for their preparation. As prepared Cu–Co films are superparamagneties. That is, they demonstrate ferromagnetic below blocking temperature, which is dependent on the size of cobalt clusters in diamagnetic matrix of copper. The granulated nanowires, firstly obtained by us, exhibit similar behavior. Special attention is paid to the analysis of obtaining and properties of multilayered films of the spin-valve type. The trends in the development of materials science are predicted, which will allow creating new materials with a high level of quality and specified properties, what will allow expanding the area of export of such materials and products from them in the future. 

The article presents the results of characterization of special powders of metal alloys and materials produced from these powders by selective laser melting (SLM), including comparative analysis of powders produced using VIGA technology. It is noted the importance of a complex study that includes not only a statistical evaluation of particle size distribution of the powders (preferably, by the method of laser diffraction), but also image analysis providing information on the particles’ shape influencing the powders’ flowability. It is shown that the size distribution and shape metrics for nickel refractory alloys and stainless steel powders obtained at the Powder Metallurgy Institute of the National Academy of Sciences of Belarus are at the level of the best foreign analogues. The influence of powder chemical composition on the mechanical properties of SLM samples is considered. The presence of oxygen and undesirable impurities, as a rule, decreases the strength and tensile strain. It is noted that SLM provides extremely wide opportunities for the formation of complex geometric structures with close to full density. Subsequent thermal or thermal and mechanical processing allows reduction of stresses arising during the SLM, densification of products (if necessary) and regulation of their structure and properties. The prospects of applying the backscattered electron diffraction (EBSD) for analysis of the material structure evolution during SLM and subsequent processing are shown. It is noted that products obtained by the SLM from the powders of special alloys exhibit mechanical properties at a level, and in some cases even exceeding the properties of these alloys produced by traditional and other additive technologies.

The purpose of this part of the research was to study the structural transformations at the transition of particlemicrocomposites from plasma flow into sprayed layer, taking into account grinding of spheroids. The results of investigations of the impulse fission of oxide spheroids in a plasma flow, the granulometric composition of microcomposites of two compositions: SiO2–TiO2, SiO2–TiO2–Al2O3 with an initial particle size of 40–50 μm, 50–63, 63–71 μm and the structure of plasma coatings from them are presented. The process of pulsed fission of spheroids in a plasma stream is found in all the compositions under study and is most intensive in systems of: SiO2–TiO2 (with initial particle size of 40–50 μm and 50–63 μm), SiO2– TiO2–Al2O3 (with initial particle size 40–50 μm). The features of the formation of structural fragments of coatings of various shapes (spheroidized and melted) and composition (completely amorphous, with multilayer shells, including amorphous ones) are studied. It is shown that the proposed technology makes it possible to obtain ceramic coatings with amorphous-crystalline structure, which features are determined by size and composition of initial microcomposites grinding of them directly in the sputtering process allows formation of finer structures in the coatings and, accordingly, significantly changing their performance characteristics and quality (adhesion strength, wear resistance is 3 times higher than that of corundum coatings, porosity is less than 1 %).

General information about development of additive technologies, as well as an overview of the main schema- tics of layer by layer manufacturing of metal products is presented. The technologies and equipment for electron beam layerby-layer production of metal products using wire and powder as a raw material is described. Experimental data obtained by the authors as a result of electron beam additive manufacturing of low-carbon steel, stainless austenitic steel and technical titanium samples are described. Relations between the product geometry and the electron beam main parameters are obtained. The analysis of microstructures is carried out. The main zones formed in the samples fabricated by this method are described. It is shown that typical microstructure of stainless steel samples consists of the large dendrites with main axes up to a few millimeters in the direction of heat sink. In a pure titanium, in addition to the characteristic coarse-grained (up to several millimeters in diameter) structure, there are zones where a lamellar structure with colonies of about 1 mm is observed, as well as a zone in the form of a strip about 1 mm wide along the walls, which is an acicular structure. This is obviously related to the cooling mode, since the character of the heat sink along the edges of the sample differs from the central zones. The analysis of electron beam additive technologies prospects is carried out. Examples of electron beam additive technology using in modern fabrication of accelerator technics, aircraft and machine building are demonstrated.

The results of investigations in the field of existing soil loading schemes by tracks of tracked vehicles and their effect on the traction force realized by a caterpillar propulsion device are presented. The review shows that most researchers emphasize the important role of lugs in the creation of tractive effort. However, most of the existing methods of calculating the traction force on the clutch are based on one or another specific design scheme that does not depend on the loads acting on the tracks, on the combination of the parameters of the grousers and on the physical and mechanical properties of the soil. The use of these methods does not allow us to consider the sequence and alternative variants of soil disruption, and also to establish
a relationship between the magnitude of the tangential force acting on the tract with a wide range of combinations of geometric parameters of the grousers, and to link it to the physical processes taking place in the soil. Consequently, these methods do not fully describe the interaction of the crawler tracks with the ground, which makes it difficult to use them to optimize the geometric parameters of the lugs. The authors proposed an analytical method for analyzing the interaction of soil with a track of a caterpillar engine based on the regularities of the theory of the limiting state of ground masses and the main provisions used in the theory of cutting soil, taking into account the revealed features of this interaction, which makes it possible to investigate the interaction of tracks of a caterpillar propulsion with soil, taking into account the multiphase and alternative options for the destruction of soil between the grousers. This method allows you to choose the parameters of the lugs, providing an improvement in traction and coupling properties of crawler tractors. 

The article proposes a new method of calculation of the indicators of the durability of the gear transmission of heavy-loaded roadheading machines, allowing a more accurate assessment of the dynamic loading of the teeth. Within the framework of this technique, the elastic moment amplification factors determined by the amplitude-frequency characteristic of transmission are used instead of the specific circumferential dynamic force in the calculation of the maximum operating voltages. The maximum stresses in the bending of teeth and the probability of failure-free operation of the technical system are determined. A spur transmission used in the drive of the Executive body of roadheader is considered as an example of application of the proposed design technique. The comparison of calculated estimations of gear transmission reliability obtained on the basis of the standard method and using amplitude-frequency characteristics is carried out. In the considered design example durability of transfer for a step cycle of loading is more than 2 times higher in comparison with a continuous cycle of loading. It is shown that using a standard calculated coefficient that takes into account dynamic load, the calculated estimations of the durability of the transmission are significantly overestimated. At the same time, the error of the standard method will depend on the frequency range at which the transmission operates, and this error is most significant when the transmission operates near its own frequencies.

On the basis of systems of identical equalities and integral boundary characteristics, a new algorithm of solving a boundary-value problem on the nonstationary heat conduction in a canonical body with boundary condition of the second kind has been developed. The scheme proposed for finding approximate analytical solutions of boundary-value problems on nonstationary heat conduction with boundary conditions of the second kind involves the introduction into consideration of a temperature-disturbance front and separation of the whole heating process into two stages. For the first stage of this process, on the basis of the differentiation of the heat-conduction equation over a space variable and the application of symmetric integral and differential operators to the expressions obtained, two sequences of integral and differential identical equalities have been constructed. Each of these sequences includes integral or differential limiting characteristics for a definite boundary condition of the second kind. For the second stage, by way of introduction of a boundary function, differentiation of the heat-conduction equation with respect to a spatial coordinate, and application of integral operators to the expression obtained, a sequence of integral identical equalities involving integral boundary characteristics for the second-kind boundary condition has been constructed. On the basis of the integral and differential identical equalities obtained, closed systems of equations, allowing one to find polynomial coefficients of the temperature profile for the first and second stages of the heating process, have been constructed. A general scheme of determining approximate eigenvalues of boundary-value problems with boundary conditions of the second kind on the basis of construction of an ordinary differential equation and transformation of it into the characteristic equation is proposed. For each of the two stages of the heating process, special integral operators, reducing the boundary-value heat-conduction problem to the ordinary differential equation, are proposed.

The effect of hydrogen additives on the working process of a piston-type gasoline engine is studied. The indicator diagram has been built, and the operation of the piston engine on gasoline-air mixtures enriched with hydrogen in the amount of 0…20 % of the volume of air entering the engine has been analyzed. The possibility of obtaining satisfactory parameters when the engine works on gasoline with hydrogen additives is shown. The dynamics of the engine performance is studied depending on the oxidant excess coefficient. It has been established that the oxidizer excess ratio at which the maximum indicator pressure is reached is moved to the zone of poor mixtures. When the mixture is enriched with hydrogen in the amount of 20 % of the air volume, the maximum of indicator pressure pimax = 5.3...5.8 MPa is reached at α = 1.15...1.25, while for 10 % hydrogen addition the maximum pimax = 4.9...5.2 MPa takes place at α = 1.05...1.10 against pimax = 4.7...5.1 MPa at α = 0.90...0.95 for pure gasoline. According to the indicator diagram, the dynamics of intra-cylinder parameters is studied when the mixture is enriched with hydrogen. Thus, with a 20 % hydrogen addition the mean indicator pressure decreases by 12...19 %, despite a slight increase in the maximum cycle pressure (3...18 %), compared with gasoline operation, which leads to a proportional decrease in both the engine indicator power, and the indicator efficiency.

The therapeutic effect of the whole body gas cryotherapy (WBGC) procedure is achieved when the average temperature of the human’s (patient’s) skin surface during the procedure is in a certain temperature range, and the rate of reduction of this temperature exceeds a certain threshold value. The paper presents the results of a theoretical analysis of the patient’s thermal state at the stage of the therapeutic effect of WBGC. The analysis was based on the results of the numerical simulation of temperature distribution in different parts of patients (mеn) of different body constitution (height, cm × mass, kg) 160 × 60, 175 × 75, 190 × 90. Particular attention was paid to the relationship between the amount of heat flow removed from the skin surface and the rate of cooling of the skin of a patient. The results of numerical modeling are presented graphically and are summarized as the ratio between the dimensionless average temperature of the skin at the treatment stage of the WBGC procedure and the time of the patient’s stay in the procedural chamber, referred to the time of the beginning of this stage. With regard to WBGC within the temperatures range of –160 to –110 °C the following regularities were found: 1) approximate constancy (descripancy less than 1 %) at the stage of therapeutic modality of the coefficient of heat transfer from the skin surface to the gas medium in the treatment chamber; 2) the exponential dependence of the value of cutaneous blood flow rate (blood perfusion) on the mean temperature of cooled cutaneous coverings; 3) linear dependence of the logarithm of the ratio of the rate of skin temperature reduction to the value of heat flux density removed by convection and radiation on the logarithm time.

Power supply system of advanced robotic systems requires the development of electromechanical energy converters with high energy and minimum weight and overall dimensions. In this regard, a free piston engine with an electric generator is considered as a promising plant.

Interest in the study of power plants based on free piston engines is caused by several advantages compared to conventional internal combustion engines with a crank mechanism: relative simplicity of the design, 40 % fewer elements, which reduces the overall capacity, specific gravity and metal content of the free piston engine in 2.5–3 times. In addition, the fuel consumption is 30 % lower. Also an important design advantage of power plants based on free piston engines is a relatively simple modular construction. Reciprocating electric generators with transverse increment of the magnetic flux are the most commonly used ones in currently developed power plants based on free piston engines of foreign countries (USA, Russia, Germany, China, UK, Japan, Sweden, Israel, etc.) as the electrical AC machines. The main disadvantage of this type of generators are the absence of coordination of electrical and mechanical subsystems of the power plant at the extreme points of the operating cycle, which limits the efficiency of the free piston engine and reduces the reliability of the power plant.

To solve this problem it is proposed to use Electromechanical energy Converter with transverse and longitudinal increment of the magnetic flux (combo generator). However, currently there is no scientifically valid method of synthesis of this type of generator. To address this problem we have developed the methodology of structural and parametric synthesis of combined generator of the reciprocating type for a plant on the basis of free piston engine, which is based on the use of the specific gravity of the combined generator as the objective function. It allows synthesizing electric machine of the reciprocating type with the specified efficiency and minimum specific mass. 

Contamination of the monocrystal silicon with technological impurities in the devices fabrication process exerts a considerable influence on the electro-physical characteristics of the bipolar n–p–n-transistors. Revelation of the causes of the labile reproducibility of the basic characteristics of the bipolar planar n–p–n-transistors is vital for the purpose of establishing the factors, determining reliability and stability of the operational parameters of the integrated circuits. There were investigated I–V characteristics of the various lots of the bipolar n–p–n-transistors, fabricated under the epitaxialplanar technology as per the similar process charts with the identical used technological materials, however, at different times. It is established that the electro-physical characteristics of the bipolar n–p–n-transistors substantially depend on the contents of the technological impurities in the substrate material. Availability of the high concentration of the generation-recombination centers, related to the metallic impurities, results both in increase of the reverse current of the collector – base junction of the transistors and the significant reduction of the breakdown voltage of the collector junction. The most probable cause of deterioration of the electro-physical parameters of the bipolar n–p–n-transistors is the material contamination with the technological impurities (such, as Fe, Cl, Ca, Cu, Zn and others) during the production process of the devices fabrication. The sources of impurity may be both the components and sub-assemblies of the technological units and the materials and reagents under usage.

The article presents the simulation of the interaction of electromagnetic waves in the mode of video pulse signals with the medium over hydrocarbon deposits. The analysis of the spectra of reflected video pulse signals from the medium over hydrocarbons is carried out. A study of the propagation of radio waves over hydrocarbons is carried out within the framework of a quasihydrodynamic approximation. The choice of the frequencies of video pulse signals is due to the determination of media characteristics over deposits at great depths compared to the surface of the earth. The spectrum of reflected signals from an anisotropic medium above a hydrocarbon deposit in the mode of video pulse signals can be used to determine the electrodynamic characteristics of the medium over the deposit over a wide range of frequencies of probed signals, dielectric permittivities and conductivity of media. The ability to reconfigure a geo-prospecting device from one mode to another (pulse width adjustment) in the presence of a deposit complements the functionality to search for hydrocarbon deposits. Electromagnetic methods for the search for and identification of hydrocarbons can be improved by obtaining information about objects through several information channels, which allows them to be identified with a sufficiently high level of reliability on the background of the underlying environment. The depths of occurrence, the resolving power in the investigated frequency range are determined. The results of the research can be used to develop new electromagnetic methods for the search for hydrocarbon deposits.