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. It is known that at present, methods of thermal spraying are widely used to restore and strengthen various worn-out machine parts. As a rule, metal coatings applied by thermal spraying have lower strength characteristics than solid materials. It is believed that the strength of coatings is proportional to their adhesive and cohesive strength. The value of adhesive and cohesive strength depends on various factors, including the nature of the materials and the technology of coating. An important factor characterizing the possibility of using metal coatings in various industries is the strength of adhesion of coatings to the base metal. The paper presents the determination of the adhesive and cohesive strength of coatings from different materials, applied by the method of hypersonic metallization. The results of testing the strength of metal coatings made of ER316LSi-grade wire, nichrome (Cr20Ni80) and molybdenum wire are given in the paper. Based on the results of metallographic studies, the proportion of the participation of cohesive and adhesive components in the strength of coatings has been determined, and some features of coating destruction have been described. It has been found that the participation of the cohesive and adhesive components of the coating strength differs depending on the material used. The cohesive component prevails in the strength of coatings made of high-alloy wire of the ER316LSi-grade, at which destruction mainly occurs along the coating-base boundary. For nichrome coatings and especially for coatings made of molybdenum, the cohesive component is predominant, in which the destruction of the coating occurs not along the coating-base boundary, but between the coating layers.

Block symmetric ciphers are one of the most important components of modern information security systems. At the same time, in addition to the structure of the applied block symmetric cipher, the cryptographic strength and performance of the information protection system is largely determined by the applied encryption mode. In addition to high performance and high-quality destruction of block statistics, modern encryption modes should also protect encrypted information from occurred or intentionally introduced errors. In this paper, we have developed an encryption mode with blocks skipping and using a pseudo-random key sequence generator, which allows checking the integrity of encrypted information with accurate detection of the place where an error was introduced. In this case, the error detection accuracy is determined by the adjustable parameter of the macroblock size and can be set depending on the level of importance of the protected information. The developed encryption mode is characterized by the following key advantages: reducing the number of required encryption operations by half, while providing a high level of cryptographic quality; more effective destruction of macroblock statistics due to the use of an additional generator of pseudo-random key sequences, the impossibility of propagation of the occurred (intentionally introduced) error outside the macroblock, as well as higher values of the number of protection levels due to the possibility of classifying the initial states of the applied generators of pseudo-random key sequences. As proposed in this paper, the mode of authenticated encryption with blocks skipping can be recommended for use on mobile platforms that are demanding both in terms of the quality and reliability of the protected information and are limited in terms of computing and power resources.

This paper is devoted to the reduction of data transfer between the main memory and direct mapped cache for blocked shortest paths algorithms (BSPA), which represent data by a D[M×M] matrix of blocks. For large graphs, the cache size S = δ×M2, δ < 1 is smaller than the matrix size. The cache assigns a group of main memory blocks to a single cache block. BSPA performs multiple recalculations of a block over one or two other blocks and may access up to three blocks simultaneously. If the blocks are assigned to the same cache block, conflicts occur among the blocks, which imply active transfer of data between memory levels. The distribution of blocks on groups and the block conflict count strongly depends on the allocation and ordering of the matrix blocks in main memory. To solve the problem of optimal block allocation, the paper introduces a block conflict weighted graph and recognizes two cases of block mapping: non-conflict and minimum-conflict. In first case, it formulates an equitable color-class-size constrained coloring problem on the conflict graph and solves it by developing deterministic and random algorithms. In second case, the paper formulates a problem of weighted defective color-count constrained coloring of the conflict graph and solves it by developing a random algorithm. Experimental results show that the equitable random algorithm provides an upper bound of the cache size that is very close to the lower bound estimated over the size of a complete subgraph, and show that a non-conflict matrix allocation is possible at δ = 0.5 for M = 4 and at δ = 0.1 for M = 20. For a low cache size, the weighted defective algorithm gives the number of remaining conflicts that is up to 8.8 times less than the original BSPA gives. The proposed model and algorithms are applicable to set-associative cache as well.

The paper deals with the problem of improving the reliability of DC-DC power supplies with pulse-width modulation. The topicality of the work is related to the importance of power supply issues in modern electronics, since the quality of operation of consumer electrical appliances, including critical ones, directly depends on the serviceability of sources. The object of the study is feedback circuits aimed at stabilization of the parameters of power supply of consumers. Failures of the mentioned feedback circuits most often occurs due to the electronic components degradation under harsh operating conditions as well as under severe mechanical overloads. Such failures are dangerous for uncontrolled increase of power supply output voltage and output current. To avoid this, a new method of reserving voltage feedback signals is presented in the paper which is implemented on the basis of flyback supply topology. Feedback signals are formed from the optocoupler located on the load side and from the auxiliary winding of the power transformer, together forming two independent output voltage control circuits. Only one circuit performs stabilization at any given moment of time. If one of these circuits fails, the second one can simply replace it in its operation. The proposed method does not require any digital signal processing algorithms or microprocessor control modules and can be implemented on the basis of cheap, widely available analog chips that perform pulse-width control of the output voltage. As a result, the problem of sudden feedback loop failure is solved and the reliability of electrical equipment is increased. The validity of the proposed method is confirmed by the results of computer simulation with the use of MatLab-Simulink environment. The obtained results can be used in design of fault-tolerant secondary power supplies that operate in harsh operating conditions.

The paper deals with the problem of increasing the efficiency of the functioning of electric networks up to 1 kV, namely, the possibility of increasing the sensitivity of protections in networks up to 1 kV, which helps to reduce the protection response currents and, accordingly, reduce the cross-section of cable and wire products. The topicality of this problem is shown and the research tasks are defined. Much attention is paid to the concept of selectivity; attention is also paid to the concepts of full and partial selectivity. “Which protective devices can be considered selective?” is a question that is considered and worked out in sufficient depth in the paper. The negative phenomena that occur when ensuring the selectivity of protections in networks up to 1 kV are systematized and described in detail. Based on a comparative analysis of the parameters of circuit breakers with release tripping devices of various types, a solution to this problem is proposed by using circuit breakers with microprocessor and semiconductor release tripping devices. Additional advantages of microprocessor-based circuit breakers are considered and indicated, as well as their disadvantages are indicated, too. The main expected positive effects from the use of circuit breakers with microprocessor release tripping devices are listed, taking into account the fact that this type of circuit breakers is considered as a complex of devices replaced by it. The article can be recommended to employees of electric power specialties working with networks up to 1 kV.

A methodological method based on the use of the theory of preferred numbers has been proposed in order to improve the most important parameters of the working bodies of noise mufflers. As a result of many years of scientific research, the authors have established a previously unknown theoretical relationship between the main series of preferred numbers, golden ratio and Fibonacci series numbers. A new direction in the development of number theory has been considered in the paper, its classification has been compiled, including the geometric theory of numbers, preferred numbers, containing a new basic series of preferred numbers using the Fibonacci sequence. New formulas have been obtained to determine the denominators of geometric progressions for the series of preferred numbers and the area of a circle. Determining the area of a circle using the new formula allows to get more accurate values. A new formula for determining the circumference of a circle has also been derived. The designs of perforated partitions have been developed, in which the laws of the new basic series of preferred numbers are used. Determining the area of a circle using the new formula allows you to get more accurate values. A new formula for determining the circumference of a circle is also obtained. The designs of perforated partitions have been developed, in which the regularities of the new basic series of preferred numbers have been used. A calculated substantiation of the main geometric and structural dimensions of noise mufflers is given using a mathematical model of a perforated golden partition and new basic series of preferred numbers, which allow to obtain a noise muffler design that has the lowest possible aerodynamic resistance with the maximum possible reduction in the noise level of exhaust gases from internal combustion engines. An innovative model of a noise muffler for reciprocating internal combustion engines with improved hydraulic and acoustic characteristics based on the theory of numbers is proposed in the paper. The theory of preferred numbers applies to any technical device.

Contact problems for elastic stripes have been well studied and published in domestic scientific literature. This is partly due to the fact that normative documents on the foundation structure it is recommended to use this elastic foundation model for simulation of a “structure – foundation – soil foundation” system. Two variants of boundary conditions at the contact between a half-strip and a rigid non-deformable base are usually considered. The first boundary condition nullifies the vertical displacements and tangential stresses, the second one nullifies vertical and horizontal displacements. Contact problems for an elastic half-strip are much less investigated. The paper considers this contact problem when the first boundary condition for zeroing of vertical displacements and tangential stresses at the contact of a half-strip with a rigid, nondeformable base. When performing calculations in the traditional formulation without taking into account tangential stresses in the contact zone, the Zhemochkin method has been used, which reduces the solution of the contact problem of solid mechanics to the solution of a statically indeterminate problem by the mixed method of structural mechanics. Therefore, at first, we have found the displacements of the upper edge of the half-strip from the unit load uniformly distributed over the edge section. The resulting expression is used to compose a system of equations for the Zhemochkin method. The case of translational displacement of the die has been considered, and the graph of contact stress distribution under the die's sole has been given in the paper.

The paper provides an overview of the known designs of water wells. A new design of a two-column two-filter water intake well has been also proposed, in which the filters are arranged in two tiers. This will lead to an increase in water intake capacity and will reduce the filtration rate on the approach to the filters. This, in turn, will create conditions for reducing head losses and will make it possible to reduce drawdowns in the well, ensuring a reduction in the cost of produced water. This design combines both working and reserve wells located in one borehole, which increases its reliability, durability and uninterrupted water supply to the consumer. A method for calculating the hydraulic parameters of a two-column two-filter water intake well is presented in the paper. It is based on dependencies for calculating the main geometric dimensions for a given design flow rate and hydrogeological characteristics of an aquifer, as well as formulas for determining a decrease in a well for a given period of operation when one and two pumps operate simultaneously. The basics of designing a well of the proposed design are outlined in the paper. The paper considers an example of calculation for a new well design instead of an existing typical well that has reduced its specific flow rate.

The paper presents studies on the optimization of the process of applying coatings from cermet powders with different solid phase contents by plasma spraying in air to restore and harden parts of machines and mechanisms operating under adverse conditions. Such conditions are usually created in heavily loaded tribojoints when the mechanisms operate at a low speed of relative movement of surfaces during friction. At the same time, the destruction of the working surfaces is mainly due to the process of microcontact setting and subsequent detachment of the formed particles at their contact points. The application of special protective coatings with the required properties is possible with the manufacture of high-quality starting powder materials and optimization of the technology for their application. Such powders and powder compositions can be obtained by the method of agglomeration of a fine powder mixture with its subsequent high-temperature sintering. To identify the hardening mechanism of composite coatings made of cermet by gas-thermal spraying, important stages are the optimization of the deposition process parameters and the study of the properties of plasma coatings obtained in this case. When optimizing the technological parameters of plasma spraying of coatings, the utilization rate of the sprayed powder material has been taken into account as the main indicator of the process efficiency, the structure of the obtained layers, and the morphology of individual particles deposited on the polished surface. The paper provides data on the structural elements of sprayed materials for wear-resistant coatings obtained by plasma spraying at optimal conditions. Taking into account the processes that occur during the wear of tribological conjugations, the data indicate the existing prerequisites for the wear resistance of the studied composite coatings made of metal ceramics. Special wear-resistant coatings made of materials with a soft matrix hardened by solid inclusions Al2O3–TiO2–Ni–Cr–Al–Y are widely used in various industries. Based on the detailed analysis of the features of cermet plasma coatings, it can be stated that such powder compositions (complex oxides-metal component) are often used as wear-resistant plasma coatings. The research results can be taken into account in cases of application of wear-resistant plasma coatings made of metal-ceramics and compositions based on them, containing solid phases in the form of oxides, as well as the manufacture of a whole range of parts operating under conditions of intense wear.

The possibility of using local materials in the construction of structural layers of pavement is considered in the paper. The paper presents a method of technical and economic analysis, for which it is necessary to know the calculated deformation moduli of the materials being compared. Knowing the turnaround time for each of the options under consideration, it is possible, by comparing them with the payback periods, to more fully identify the technical and economic features of such options. The main criterion for the admissibility of the use of local material in the corresponding structural layer is the equal strength of pavement structures or individual structural layers made of local and imported materials. The criterion of economic feasibility of using local material can be written as an inequality. Using the principle of equivalence of systems, it is possible to replace individual structural layers of pavement, made of certain materials, with equivalent layers of stiffness from other materials, increasing or decreasing their thickness, depending on the strength characteristics of the materials themselves. The main condition for the technical feasibility of using local material has been determined on the basis of the condition of equal strength structures made from local and imported materials. A schedule for preliminary determination of the technical and economic feasibility of using local materials in the structural layers of road pavements has been built. The total value of the investment costs can be used as an additional criterion for the economic benefits of the compared options.

Over the past few years, a group of new processes was developed for high-temperature, including plasma electric arc spraying (at ambient pressure) and spheroidizing of some ceramic and metal powder materials with the use of gaseous hydrocarbons in the heat carriers as well as with feeding of organic additions into a high-temperature jet, in particular, polymeric ones, to control porosity of sprayed metallic functional coatings. The paper considers the possibility to modify such technological processes by introducing solid fuel additions of a polymer type into the operating fluid of an apparatus for gasthermal (plasma or other) treatment, which provides melting of metal or oxide powders. For this, with the help of thermodynamic analysis, the processes have been evaluated at temperatures (300–3000) K for the set of such reacting five component systems as C–H–O–N–Me (at ambient pressure 0.101 MPa) with five variants of Ме – aluminum, titanium, chrome, copper, nickel. This makes it possible to consider these systems as simulants for potential technologies for the treatment of oxide powders (Al2O3, TiO2, Cr2O3) as well as metallic ones (Cu, Ni and their alloys). In order to obtain high exothermic contribution to the heating of powders, the combination “air + polymeric addition (polyethylene) of LDPE grade” was chosen as mixed heat carrier (operating fluid) for the basic version of simulated process. During the analysis of equilibria for the considered multicomponent systems (17 variants), a set of following parameters has been used to characterize the energy intensity of the target powder heating process: the equivalence ratio for reacting mixture and its adiabatic temperature; the energy efficiency of material heating with and without taking into account the effect of fuel addition; specific energy consumption for the powder melting; autothermicity degree of the process during the combined heating (electrothermal heating by the arc of plasma torch and heat flux from the “air + solid fuel additions” mixture) of refractory powders. As a result of the assessment, the preferred (from thermodynamic standpoint) regimes of the considered processes have been found and the possibility to realize an energy-efficient heating of these oxide and metal materials (without oxidation of the latter to CuOx, NiO) with a reduced part of the electric channel of energy transfer, resulted from the carrying out of appreciable effect of the fuel-initiated mechanism of heating in the analyzed C–H–O–N–Mesystems, has been shown in the paper.

The purpose of this study is to develop a circuit for an automobile air conditioner, which will reduce the consumption of power developed by the engine. This paper proposes the design of an automobile absorption air conditioner. A description of the principle of operation of an automobile absorption air conditioner operating on a cycle of a one-stage absorption refrigeration machine has been given in the paper. It consists of a stripper (generator), a condenser, an absorber, an evaporator. Lithium bromide (LiBr) solution has been used as an absorbent, which has a low boiling point, is non-toxic and safe. 3D-models of the absorber and generator of an automobile absorption air conditioner has been developed in the course of the research. The absorber is designed to form a weak absorbent solution. This solution is supplied to the generator heat exchanger using a liquid pump. There it is heated by the exhaust gases to the boiling point. The solution evaporates and water vapor enters the condenser (evaporator). In the generator, the solution is concentrated from 52 to 60 %. After that, water vapor is supplied to the absorber from the condenser, and a concentrated absorbent solution is supplied from the generator. It should be noted that the generator is a key element of an automobile absorption air conditioning system. Inside it is a strong LiBr solution that feeds the absorber. The design of the air conditioning system does not provide for the use of a compressor and allows to reduce the power loss of the power plant to the drive of the liquid pump. According to calculations, the pump drive power was 0.17 kW. For comparison, the compressor of a modern car air conditioner consumes 7–11 kW. An absorption car air conditioner provides the following advantages: additional engine cooling, environmental friendliness, fuel economy, efficient use of the heat of vehicle exhaust gases. A distinctive feature of this design is that it is proposed to use the heat of the exhaust gases for the process of heating the absorbent. This design can fully compete with the existing modern car air conditioners.

The paper presents a comparative theoretical analysis of the movements of the curved rods of various curvature forms, which can be applied as tools for ultrasonic treatment of holes in fragile materials. It has been shown that the traditional processing of holes by an ultrasonic method is based on the use of straight rods, in which the amplitudes of displacements on the working – free end corresponds to the value of displacements at the point of its attachment to the ultrasonic oscillation concentrator. Supplementing the configuration of a straight rod with a curvilinear shape in the form of a circular arc or a spiral twisted by one turn will allow obtaining additional displacements caused by the elastic properties of a section with a curved shape. The paper considers several calculated schemes of a curvilinear rod bounded by angles j equal to p/2, p and 2p, fferent direction of the external force action. The obtained results have shown that an increase in the circular arc angle leads to a corresponding increase in the elastic displacement index of the rod free end. In this case, the total displacements of the rod free end will be made from displacements caused by vibrations of the acoustic system and the displacements of a curved thin rod from an external force. Calculations have established that the magnitude of the elastic displacements of curved rods is influenced by the shape and magnitude of the angle, the direction of the external force, the radius of curvature, the rigidity of the cross section. The considered schemes of thin rods with curvilinear sections can find practical application in ultrasonic oscillatory systems for processing small-diameter holes in fragile materials. This increases the intensity of tool oscillations and improves the process performance.

The paper presents a mathematical model developed for calculating the force effect on the punch in the process of high-speed combined hot extrusion of bimetallic road milling picks under plane deformation conditions. To solve the problem, the process is divided into two phases: acceleration phase and braking phase, which consists of two stages. A distinctive feature of the acceleration phase is that it allows the analysis of reverse extrusion, in the process of which the metal flows in the opposite direction to the punch stroke. A method for calculating the force acting on the punch at each phase of the process of plastic flow of a bimetallic workpiece into a matrix cavity with three deformation zones is presented in the paper. While solving the problem in a quasi-static formulation and proceeding from the conditions of the minimum power of internal forces, equations have been obtained for calculating the optimal field parameters aopt, bopt, gopt, depending on the elongation coefficients l and the friction coefficient m. The equations obtained within the framework of the developed model are quite correct, since they allow determining the minimum force acting on the punch. The considered calculation model and equations can be used in the development of industrial technology for high-speed combined hot extrusion of flat-step bimetallic road milling picks.

Having proven its effectiveness in finding the best options for energy supply and energy consumption the exergetic method of thermodynamic analysis of complex heat and power systems has been widely recognized in recent years. However, its application is hindered by the lack of appropriate scientific and methodological heat technology support, especially if their application involves not only transformation of energy, but also transformation of substances. Heat treatment of concrete and reinforced concrete products belongs to such technologies. This article presents new scientific results related to the development of exergetic balances of the processes of preparation of concrete mixture in a mixer and heat treatment of a concrete product in a heat-technological installation. For each of these cases, the analysis of exergetic flows was carried out, the structure of the exergy of the concrete mixture and the hardening concrete was determined. Based on the analysis of the literature data on the chemical composition of cement clinkers, cements, and hydration products, new dependences have been proposed for calculating the exergy of the concrete mixture flow and the exergy of concrete under its heat treatment, including all their components, viz. thermomechanical, reaction, and concentration constituents. Absolute energy indicators have been developed. The calculation of the mentioned values was performed on a specific example with the use of the developed scientific and methodological support. In the second part of this paper, the results of the study related to the determination of relative exergetic indicators that allow evaluating the energy efficiency of the processes of heat treatment of concrete products in heat technology installations will be published. The results obtained in this paper can be used for the selection of energy-saving modes of heat-technological equipment intended for industrial heat treatment of concrete products.

In recent years, intensive research on urban transport has been observed. The search is about finding such solutions that will enable, among others: increasing the importance of public transport, matching transport for the needs of people with reduced mobility, increasing capacity, reducing emissions, energy efficiency (technical and organizational dimension through the organization of transport on demand), increasing the vulnerability to recycling and remanufacturing. The paper presents the main concept and technical solutions of the innovative transport system – HMASSUT Prometheus (Hybrid Modular Autonomous System for Sustainable Urban Transport), which combines the concepts of personal rapid transport and an electric vehicle at the L4 autonomy level (according to the Society of Automotive Engineers classification). An assessment of the effectiveness of an innovative transport system using indicators used in road engineering is given in the paper. The concept of simulation and optimization of the transport network is presented together with the theory of cellular automata.

A schematic and structural solution of regenerative-utilization heat use in centralized heat supply systems was previously proposed in order to increase the efficiency of operation of heating networks located in non-passable channels. The impossibility of creating a full-scale experimental setup covering the required range of factors and the area of their change, the complexity of a passive experiment on existing heating mains led to the need to develop a virtual model based on the ANSYS sofware package. A six-factor experiment has been carried out on this virtual model. Regression equations have been obtained to determine the pressure required to provide air purging of the channel, as well as heat exchange with pipelines of direct and return network water located in the channel, and heat exchange with soil around the channel. In addition, a regression relationship has been derived to find the integral heat flux from the listed washed surfaces to the air flow. The transition from dimensionless to natural factors has been made in the paper. The most significant factors are identified with the help of Pareto cards. The obtained dependencies have been verified in Part 1 of the paper. The adequacy of the obtained regression equations has been determined using standard statistical estimation methods based on the calculated values of the Fisher’s, Student’s and other criteria. The response surfaces are presented and analyzed using two dimensional sections for a number of factor values at fixed values of one and a change in two most characteristic, physically significant for a given response function. They have been validated on the basis of the analysis of regression dependencies. The obtained regression equations cover almost the entire range of possible diameters of heating mains, which makes it possible to use them in the development of energy-saving projects.

The most common and reliable material without which modern construction is indispensable is concrete. The development of construction production is pushing for new solutions to improve the quality of concrete mix and concrete. The most demanded and significant indicators of a concrete mixture are the compressive strength and mobility of the concrete mixture. Every year, the volume of research on nanomaterials as modifying components of concrete is significantly increasing, and the results indicate the prospects for their use. Nanoparticles with a large specific surface are distinguished by chemical activity, can accelerate hydration and increase strength characteristics due to nucleation and subsequent formation of C–S–H and compaction of the material microstructure. Sol of nanosilica, which can be used instead of microsilica from industrial enterprises, and carbon nanomaterial have a wide reproduction base. This paper presents studies of these types of nanomaterials and the results of their application in cement concrete. Studies have shown that the effect is also observed with the introduction of an additive containing only one type of nanoparticles. The dependence of the obtained characteristics of cement concretes on the content of these nanomaterials has been established. It has been found that the best results were obtained with an additive in which the above-mentioned nanomaterials were used together. Compressive strength of heavy concrete samples, improved by the complex nanodispersed system, was 78.7 MPa, which exceeds the strength of the sample containing the CNT additive in a pair with a super-plasticizer by 37 %. The paper proposes the mechanism for action of the presented complex additive.

The paper describes a technique for assessing the thermally stressed state of a concrete massif of a foundation slab made of a self-compacting concrete mixture. The proposed method consists in a preliminary calculation of temperature fields in hardening concrete. The objects of research have been self-compacting concrete mix and structural concrete in the structure mass. The choice of materials for the preparation of a concrete mixture is given and substantiated. The composition of self-compacting concrete has been used to assess the thermally stressed state. A binder with a reduced exotherm has been used in order to reduce the self-heating of concrete. Studies have been carried out to assess the specific heat release of the recommended cement depending on the initial water-cement ratio. The effect of a chemical additive on the rate and magnitude of the specific heat release of cement has been studied. The paper presents the main theoretical provisions and an algorithm for calculating the thermal stress state of a concrete massif. The finite difference method has been used to calculate the expected temperatures and their distribution in the structure mass, and the temperature stresses in the sections of the concrete mass have been calculated to assess the thermally stressed state. The performed calculations of the temperature fields have made it possible to estimate the maximum possible temperatures and temperature differences over the sections of the concrete massif depending on the initial temperature of the concrete mixture and the average daily temperature of the outside air. Analysis of the temperature distribution has revealed the most dangerous sections of the concrete mass. An assessment of the thermal stress state of the concrete mass has been made on the basis of the results pertaining to calculation of temperature fields. The calculation of temperature stresses in the most dangerous sections of the concrete massif has been performed. It is shown that the calculated value of the temperature stress can serve as a characteristic of the thermally stressed state of the concrete mass. The formation of temperature cracks in a concrete mass is possible when the calculated value of the temperature stress exceeds the actual tensile strength of concrete. Comparison of the calculated and actual values of temperatures in the sections of the foundation slab has made it possible to conclude that the calculations of the temperature fields and, as a consequence, possible temperature deformations are correct.

Road traffic accidents of vehicles with a rolling stock of railways lead to the most serious consequences. Many level crossings are places of long delays of vehicles both before and after the traffic. In this case and in many others, the intersections of highways with railways sharply limit the capacity of the highway. Level crossings require the utmost attention of the traffic organization, since they must include not only devices for the movement of cars, but also pedestrian and sidings. Despite the fact that the problem of road traffic accidents at level crossings is not new, research and analysis of statistics in this area continues around the world. The paper considers the level crossings on the Republican highways of the Republic of Kazakhstan. Research has been carried out on ways to improve traffic safety at such crossings. The situation at the level crossings of the roads of Republican significance, as well as possible restrictions and regulatory requirements, have been studied in the paper. The paper presents results of a detailed collection of data at the facilities, which will serve as the basis for the development of a detailed program for improving the regulatory and technical base of the road sector in Kazakhstan to improve the safety of road transport infrastructure, taking into account existing standards. Recommendations are given for the implementation and generalization of advanced international experience in organizing road traffic at railway crossings, which will contribute to the adaptation of the Republic of Kazakhstan in the context of the development of transport and communications.

The mixed problem for the telegraph equation well-known in electrical engineering and electronics, provided that the line is free from distortions, is reduced to a similar problem for one-dimensional inhomogeneous wave equation. An effective way to solve this problem is based on the use of special functions – polylogarithms, which are complex power series with power coefficients, converging in the unit circle. The exact solution of the problem is expressed in integral form in terms of the imaginary part of the first-order polylogarithm on the unit circle, and the approximate one – in the form of a finite sum in terms of the real part of the dilogarithm and the imaginary part of the third-order polylogarithm. All the indicated parts of the polylogarithms are periodic functions that have polynomial expressions of the corresponding degrees on an interval of length in the period, which makes it possible to obtain a solution to the problem in elementary functions. In the paper, we study a mixed problem for the telegrapher’s equation which is well-known in applications. This problem of linear substitution of the desired function witha time-exponential coefficient is reduced to a similar problem for the Klein – Gordon equation. The solution of the latter can be found by dividing the variables in the form of a series of trigonometric functions of a line point with time-dependent coefficients. Such a solution is of little use for practical application, since it requires the calculation of a large number of coefficients-integrals and it is difficult to estimate the error of calculations. In the present paper, we propose another way to solve this problem, based on the use of special He-functions, which are complex power series of a certain type that converge in the unit circle. The exact solution of the problem is presented in integral form in terms of second-order He-functions on the unit circle. The approximate solution is expressed in the final form in terms of third-order He-functions. The paper also proposes a simple and effective estimate of the error of the approximate solution of the problem. It is linear in relation to the line splitting step with a time-exponential coefficient. An example of solving the problem for the Klein – Gordon equation in the way that has been developed is given, and the graphs of exact and approximate solutions are constructed.

Waste generation in the life of people and enterprises is an inevitable process today. The level of utilization of municipal waste has increased on average to 23 % in Belarus. The paper provides an assessment of the existing systems for the collection and disposal of waste solid household items based on technological stages (preparation of waste for loading into a garbage collection vehicle; organization of temporary storage of waste in households, at enterprises; collection and removal of waste from the territories of households, organizations and enterprises; neutralization, processing and recycling of waste). The consequences of untimely collection of solid household and industrial waste are considered in the paper. The paper presents the factors that have a harmful effect on the human environment and the ecology of the territories of settlements and enterprises. An analysis of the effectiveness of the timely removal of such components in the systems of municipal services of cities and enterprises as an important component providing social, economic and environmental significance is given in the paper. At the present stage of the development of technology and available technologies, one of the most rational and economically justified ways of delivering waste to the areas for their sorting and processing is vacuum transportation using pipeline transport. Its application is justified for industrial zones and settlements with high and medium population density. Moreover, such a pipeline can be laid next to existing pipeline and other transport communications.

The paper presents the results of research on the dynamics of end milling of thin-walled work-pieces having complex geometric shapes. Since the milling process with shallow depths of cut is characterized by high intermittent cutting, the proportion of regenerative vibrations decreases, and the effect of forced vibrations on the dynamics of the process, on the contrary, increases. The influence of axial depth of cut on the vibrations arising during processing, and roughness of the processed surface have been studied in paper. The experiments have been carried out in a wide range of changes in the spindle speed at different axial cutting depths. Vibrations of a thin-walled work-piece have been recorded with an inductive sensor and recorded in digital form. Then an oscillogram has been used to estimate the amplitude and frequency of oscillations. The profilograms of the machined surface have been analysed. Roughness has been evaluated by the parameter Ra. The results have shown similar relationships for each of the investigated axial cutting depths. The worst cutting conditions have been observed when the natural vibration frequency coincided with the tooth frequency or its harmonics. It is shown that the main cause of vibrations in high-speed milling is forced rather than regenerative vibrations. Increasing the axial depth of cut at the same spindle speed increases the vibration amplitude. However, this does not significantly affect the roughness of the processed surface in cases when it comes to vibration-resistant processing.

The paper provides a comparative analysis of the influence of ring concentrator shape in ultrasonic systems on their amplitude-frequency characteristics. Devices are known in which elastic elements are used either as resonators or as working tools of ultrasonic technological systems. However, the use of elastic elements as concentrators of ultrasonic vibrations is insufficiently studied and requires comprehensive research and development of recommendations for their practical application. For this purpose, a theoretical analysis has been carried out in the paper while using the ANSYS computer program, which made it possible to perform modal and harmonic analysis of ring models with various shapes. The round ring has a nominal outer diameter of 50 mm and a variable cross-section. Three ring models have been analyzed: one round model and two models of oval shape. To conduct a comparative analysis and identify frequencies at which resonance occurs, the vibration characteristics of the rings have been considered in the frequency range from 1 to 26 kHz. Results of the analysis show that, depending on the frequency of forced vibrations, bending vibrations are formed in the rings, which act in different coordinate planes. In this case, a change in the shape of the rings is accompanied by a change in the amplitude of the bending vibrations. The most intense ring vibrations along the vertical axis have been achieved in circular rings. It has been found that with an increase in the frequency of forced oscillations, an increase in the number of oscillation periods is observed. If in the region of low vibration frequencies only a one-period vibration mode is formed in the ring, then in the region of ultrasonic vibrations the number of vibration periods increases to two and three. All the considered ring models have several natural vibration frequencies with a certain periodicity in different coordinate planes depending on the shape of the rings. The intensity of the vibrations is different in different directions and depends on the shape and frequency of the forced vibrations. Examples of vibration mode variations for various ring shapes are demonstrated in the paper.

The purpose of this paper is a spectrum analysis of signals of various nature, construction of the signal scalogram using Morlet wavelet, modification of the scalogram to obtain a more informative graphic representation of the signal. Spectral analysis of the signal is constructed by means of the Fourier transform. A modification of the graphical representation of the result of the wavelet transform has been developed with the help of the Mathematica system. For this, a wavelet scalogram has been used as a two-dimensional representation of the original signal. A scale has been introduced on it for the value of the signal amplitude depending on the time and period of its constituent components. This graphical representation allows us to obtain additional information about the dynamic properties of the original signal. A modification of the representation of the original signal scalogram has been developed for a more complete spectrum analysis (determination of the period of the constituent components). The paper contains an example using a modified scalogram for the analysis of a signal containing two pulses, an audio signal and white noise. The basic wavelet in this case is the Morlet wavelet. A comparison of the scalogram, obtained using the built-in function, and the modified scalogram has been made in the paper. The disadvantage of the first scalogram is the impossibility of assessing the frequency of the signal; its advantage is the ability to assess the localization of the pulse. For a modified scalogram, the advantage is the estimation of the signal periodicity, and the disadvantage is the inaccuracy in determining the range of pulse localization. For spectrum analysis in Mathematica, it is recommended to use a combination of two approaches (using a standard built-in function to determine the localization of the pulse) and a modified scalogram (to determine the periods of the constituent components).

The bilinear programming problem is considered, where a column, which corresponds to one of the variables, is not fixed but can be chosen from a convex set. This problem is known as the Dantzig – Wolfe problem. Earlier, a modified support method was proposed to solve the problem, using the decomposition of the problem constraints of the Dantzig – Wolfe method. The author of the paper has developed a direct exact method for solving the formulated problem. The method is based on the idea of the solving a linear programming problem with generalized direct constraints and a general concept of an adaptive solution method. The notions of support, support plan, optimal and suboptimal (e-optimal) plan are introduced which is a given approximation of the objective function to the optimal plan of the problem. Criteria for optimality and suboptimality of the support plan have been formulated and have been proved in the paper. The search for the optimal solution is based on the idea of maximizing the increment of the objective function. This approach allows more fully to take into account the main target and structure of the problem. Improving a support plan consists of two parts: replacing the plan and replacing the support. To find a suitable direction, a special derived problem is solved while taking into account the main constraints of the problem. The replacement of the support is based on the search for the optimal plan of the dual problem. The method leads to an optimal solution to the problem in a finite number of iterations (in the case of a non-degenerate value).

The permanent magnetic field in addition to electromagnetic radiation has a significant effect on performance of devices. This is particularly true for highly sensitive precision measuring equipment, such as, for example, magnetometers or photomultiplier tubes. In this regard a new high-performance materials for protection against permanent fields and electromagnetic radiation need to be developed. The purpose of this paper is a development of a hardware and software complex for high-precision determination of permanent magnetic field attenuation coefficient and certification of protective materials.This paper describes an experimental installation for determining the attenuation coefficient of a permanent magnetic field using materials and coatings on standard package for electronic equipment. The installation ensures a uniform magnetic field flow in the measurement volume. The advantage of the measuring device is the ability to measure magnetic field in three coordinates due to the use of three pairs of Helmholtz coils and a three-dimensional Hall sensor. The software will enable to control of the magnetic field in all three directions, simulating the real operating conditions of devices that require protection from such influences. In addition, a movable positioning system makes it possible to compensate for the Earth's magnetic field, which increases the accuracy of estimating the attenuation coefficient by protective materials in weak magnetic field.An alternative use of the capabilities of the installation is to test the performance of the devices in a permanent magnetic field and evaluate the electromagnetic compatibility. Experimental results of the work includes determination of the magnetic field attenuation coefficient using standard photomultiplier tube package made of electrolytically deposited permalloy and the sheet of annealed permalloy. Thus, the effect of annealing and closed magnetic circuit on the degree of weakening of the magnetic field is shown. It has been demonstrated that annealing which causes a significant increase in the magnetic permeability promotes an effective attenuation of weak magnetic fields (up to 1 mT). In magnetic fields with an induction of 1 mT or more, effective attenuation is provided by a closed magnetic circuit.

The paper presents main trends in growth and generation of waste, depending on increase of world GDP and the population of the planet. The main directions in extending the concept of national strategies for sustainable development have been considered with due account of energy and resource conservation problems, as well as the need for the rational use of natural and secondary resources in all countries of the world community. The energy potential use of combustible waste that has not found technological application is considered by many countries as one of the priority areas in the field of unconventional energy. The paper describes the main directions in application of the technology for briquetting multicomponent compositions into solid fuel. The developed production technology makes it possible to process waste products by briquetting them with the addition of various binders, and on the example of a binder component in the form of viscous hydrocarbon-containing waste, the main technological features of obtaining solid multicomponent fuel are presented in the paper. The paper describes the equipment for electrohydraulic treatment, which operates as a part of the preparation line for briquetting of the applied oily waste and that allows to reduce the sulphur content in the waste used, and such approach in general permits to regulate the environmental characteristics of harmful substance emissions at the maximum acceptable level. Taking into account the application aspects of the technology for wet briquetting of materials, the paper reflects the main results of the obtained dependences of humidity on productivity according to the content of the binder component. The proposed algorithm for solving the problem makes it possible to rationally use of substandard combustible industrial waste to obtain a multicomponent solid fuel, while at the production stage, the energy and environmental aspects of the resulting fuel are taken into account with due consideration of the component composition of the fuel.

The paper considers an issue of transition to digital management technologies in the field of construction and housing and communal services in Russia, as well as in other countries. An optimization methodology for the application of the digital economy has been developed using the example of the existing real estate management system in the Stolichny Microdistrict of Izhevsk city (Udmurt Republic, Russian Federation). The existing and developed new projects of digital technologies are described, the introduction of which will increase the efficiency of the construction and operation of residential buildings. A methodology has been formed for creating an optimization mathematical model for managing construction and operation projects of energy-efficient residential buildings. Prerequisites and a scheme for the joint implementation of this model and digital technologies are given to improve the quality of construction and operation of residential buildings. The paper proposes a phased methodology for the introduction of digital technologies in urban planning, as well as in the field of housing and communal services within the framework of the national program “Digital Economy of the Russian Federation”. The advantages of using block-chain technology in the management of projects for the construction and operation of energy-efficient residential buildings have been studied in the paper. The application of the developed methods that meet the needs of participants in construction activities, as well as the housing and utilities sector, will improve the efficiency of not only the management system for the construction and operation of energy-efficient residential buildings, but also the overall effectiveness of the introduction of digital management in real estate. The proposed ABRIS software can be used in housing and communal services to optimize and track the expenditure of resources vital for a comfortable living of the population.

The reform of the energy sector in the Republic of Belarus, which in the last few years has moved to the stage of active implementation, will bring significant changes in the management of energy enterprises. The introduction of risk management for energy enterprises will become a necessary stage, which is justified by the transition of the energy sector to market relations. In this regard, it is necessary to consider the main issues of risk assessment for energy enterprises. The paper proposes a method for qualitative and quantitative analysis of all the risks that an energy enterprise may face in the process of energy generation. The approaches of various authors to the algorithm of qualitative risk analysis have been considered in the paper. This has made it possible to clarify the main tasks that need to be solved when conducting a qualitative risk analysis. The paper also presents an analysis of methods for quantitative risk analysis. The most commonly used methods include scenario analysis and mathematical statistics, analogy and analytical methods, methods for assessing losses, expert assessments and the theory of statistical games. Each of these methods has its own advantages and disadvantages. The performed analysis of quantitative risks has permitted to substantiate the choice of methods applicable to the energy sector, taking into account the specificity of activity type. The paper has studied various scales for estimating the probability and possible losses from risks. A comparative analysis of these scales is presented and the choice of a scale for energy enterprises is justified in the paper. Attention has been paid to the problem of probability classification pertaining to occurrence of risk events. The methodology for determining the value of possible losses when performing a risk event has been considered in detail. Potential losses are classified into the following groups: interruptions in the technological process, consequences for people, environmental consequences. Possible financial losses, as well as losses from the position of the law and reputation, have been considered separately. A critical review of risk management methods has been performed in the paper. The paper has identified the most promising methods of risk management for energy enterprises

The object of the study is durability of expansion joints in bridge structures; the subject of the research is the vibration response of a structure obtained under conditions of natural operation. Diagnostics of the road bridge expansion joints has been carried out in order to identify characteristic dependences between the value of structure vibration response and types of expansion joint designs during the period of their operation while taking into account the features of the bridge structure. For this purpose, we have tested the methodology for collecting and processing data on the vibration response of the structure under natural conditions of its operation. The paper presents results of data collection on the coverage topology which have been obtained while using three-dimensional scanning method. Data collection on the vibration response of the structure has been carried out by measuring the vibration velocity and deformation of the structure. The data obtained are analyzed. As a result of testing and analysis of the obtained data, the main characteristics have been revealed: the value of base unevenness, the amplitude of vibration velocity and vibration displacement of the structure elements. Two main parameters of the dynamic impact have been assigned, adjusted for the mass of a moving vehicle, which can be used as main parameter for assessing the magnitude of the dynamic impact. A comprehensive method for assessing the dynamic impact on bridge structures has been developed and proposed in the paper, and its use will make it possible to differentiate various designs of expansion joints according to the magnitude of the dynamic impact of vehicles. This, in its turn, will contribute to formulate new recommendations on the use of specific types of expansion joints for various categories of highway, which will increase operational durability of expansion joints and the structure as a whole.

New two-layer wear-resistant coatings of the composite type “thermal diffusion layer – vacuum ion-plasma coating TiAlN” have been obtained, their durometric and tribological properties have been investigated in the paper. The study has made it possible to establish influence of preliminary thermochemical treatment of a steel substrate on the formation of surface thermal diffusion layers is significantly higher than on unhardened steel substrates. Thus, the nano-hardness of TiAlN 1 μm-thickness coatings on substrates with a carbonitride layer when indented to a depth of 0.1–0.9 μm, is 1.9 times higher, the elastic modulus is 1.7 times higher, the ductility index H/E* is higher by 13.0 %, the rate of elastic recovery H2/E* and the rate of plastic deformation resistance H3/E*2 – have been increased by more than 2.1 and 2.4 times, respectively. The fracture toughness has been increased by 4.5 times. Preliminary boriding of the steel substrate leads to an increase in the actually measured nanohardness of the coated surface up to 1.8 times, elastic modulus up to 1.8 times, H3/E*2 – up to 1.8 times, H3/E*2 – up to 1.8 times, surface hardness – up to 10.0 %, while maintaining or increasing the plasticity index H/E up to 8.0 % in comparison with the characteristics obtained by nano-indentation of the TiAlN coating on an unhardened steel substrate. The discovered phenomenon is associated with an increase in the contribution of the hardened substrate to the elastic restoration of the coating and the indentation response of the surface. The paper presents the results of practical application of the developed wear-resistant compositions.

The paper presents research on the effect of technological parameters of high-energy processing on the performance properties of powder coatings made of cermet. The use of pulse-plasma treatment is considered as an example of high-energy modification of coatings. As used powder coating materials, various versions of carbide-containing ceramics with the addition of a solid lubricant in an iron-based metal matrix have been selected in the paper. Coatings of carbide-containing ceramics with the addition of a solid lubricant in an iron-based metal matrix on are being developed to replace those of a nickel-based matrix. Such factors as crack resistance, wear resistance, workability, brittleness, as well as economic components often limit the use of powder materials based on carbide ceramics with the addition of solid lubricant in the matrix based on nickel. When only the wear process determines the service life of a part, such powder materials should be replaced with cheaper powder materials based on carbide ceramics with the addition of solid lubricant in an iron-based matrix. The proposed developments increase the wear resistance of the plasma coating due to the introduction of high-chromium steel and molybdenum into the material. Optimum porosity is formed in the initial powder mixture during the synthesis of FeCrMo–MoS2–TiC composite materials, there is an improvement in the technological parameters of powder materials, their utilization rate in plasma spraying increases, and the technology of applying wear-resistant plasma coatings becomes cheaper. The addition of the Mo element to the FeCr binder increases the wetting of titanium carbides by the binder melt during self-propagating high-temperature synthesis of the developed composite powder. Subsequent layer-by-layer processing of plasma-sprayed coatings from powders of the developed ceramics using repetitive pulses of plasma flows using different energy levels makes it possible to create strictly defined structures with necessary and controlled porosity, which decreases in a certain sequence from the outer treated layers to the base. Such treatment contributes to a significant increase in the wear resistance of the treated friction surfaces, increases the oil holding capacity, in addition, an increased adhesive and cohesive strength of the formed layers bordering the substrate is formed. Processing distances, the total number of impacts have been varied in accordance with the methodological developments, when changing the applied technological characteristics of pulse-plasma effects. The total number of plasma pulses influences on the created thickness of the plasma coating layers after treatment and contributes to the melting with compaction of the coatings obtained by the plasma treatment and the creation of a structure with hardened characteristics.

Incompliance of the settings of the system to control actual values of the parameters of a variable frequency induction electric drive may sometimes result in complete non-operability of a variable frequency electric drive as well as in the considerable reduction of the dynamic quality parameters. Such parameters as active rotor resistance, rotor inductance, and inductance of the magnetization circuit are available for the immediate measuring. They are not identified in terms of the acceptance tests, and the values presented in catalogues and reference books are calculated ones that may differ considerably from the real values of a certain machine. Despite constant studies by the researchers, a task to identify electromagnetic parameters of the equivalent circuit of an induction motor is still important and topical. The objective of the paper is to develop a method of online-identification of the electromagnetic parameters of an induction motor making it possible to implement accurate regulator adjustment of the frequency control system in terms of operational changes in the driving motor parameters. For the first time, the paper analyzes a steady mode of induction motor operation which does not apply T-network of the equivalent circuit of an induction motor. An approach has been proposed relying on the equation of an induction motor in three-phase fixed coordinate system obtained on the basis of the theory of generalized electromechanical converter.

In the operation schemes of optical electronic devices (OED), such as digital autocollimators, direction finders, Shack-Hartmann sensors, as well as astro-orientation systems, projection measuring systems, geometric calibration schemes for OED, the photo-detector acts not only as a receiving device, but also as a measuring device. The tasks facing the OED photo-detectors. The solution to the problem is the use of several photo-detectors installed on one electronic board. Since OED photo-detectors act, inter alia, as measuring devices, it is necessary to perform their geometric calibration. Geometric calibration involves the measurement of interior orientation parameters used in the processing of OED images. Geometric calibration makes it possible to eliminate errors in mutual exposure of photo-detectors on one electronic board installed in the focal plane, as well as distortions introduced by the OED lens, primarily by distortion. The correctness of the interior orientation parameter determination is influenced by the relative position of the collimator, with the help of which the geometric calibration is performed, and the calibrated OED itself, i. e. the external orientation elements. The task is to separate the interior orientation parameters and the elements of external orientation. This is achieved using the method of mathematical processing of measured data in the forward and inverted positions of the collimator. This method of geometric calibration allows to use it for geometric calibration of OED with a large number of photo-detectors. The paper presents the results of the geometric calibration of the interior orientation parameters when the collimator projects a test object onto three photo-detectors of the OED layout. The factors influencing on the accuracy of the geometric calibration of the interior orientation elements for OED are determined in the paper. The developed method for geometric calibration of the interior orientation parameters for multi-matrix OED provides high measurement accuracy – not more than 0.1''–0.2''.

Nowadays there are a lot of modern technologies in electronic lexicography: speech synthesis technology, cross-referencing between dictionary modules, spell-checking functions, etc. The increasing availability of online information has necessitated intensive research in the area of automatic text summarization within the Natural Language Processing community. Belarusian scientists are also interested in this sphere and new lexicographical approaches for creating a linguistic database are shown in the paper. The authors present English-Belarusian-Russian electronic dictionary TechLex. This is the project of the 2nd English Department and the Department of Software for Information Systems and Technologies of the Belarusian National Technical University. The linguistic database of the dictionary is compiled not by the traditional method of processing a large number of paper dictionaries and combining the received translations, but by sequential processing of scientific and technical English-language periodicals. While the designing the dictionary the authors have taken into account the analysis of modern electronic multilingual translation dictionaries and created a client-server application in the Java programming language. The client part of the system contains a mobile application for the Android operating system, which has been tested on tablets and smartphones with different screen diagonals. The interface of the TechLex dictionary is designed taking into account the possibility of adding new subject areas and filling them with appropriate lexical material. The main advantage of our dictionary is that it is the first technical multilingual electronic dictionary having a Belarusian version.

Erosion is divided into two stages in accordance with the accepted design scheme for erosion of a soil dam during overflow. The paper deals with the first stage, when the downstream thrust prism is washed out. The key factor in calculating erosion deformations is the choice of the solid flow rate formula. Studies show that the mechanism of formation and transportation of solid runoff during erosion of dam models from sandy oils is very similar to that previously described by many authors for the condition of river channel erosion. The peculiarity of the process is that the erosion occurs at high speeds. Therefore, solid runoff almost immediately goes into a suspended state. To select the required formula, experiments have been carried out on models of dams made of sandy soils having various granulometric composition. It has been established that at high velocities under the considered conditions, the value of the solid waste flow rate depends solely on hydraulic characteristics of the flow. The influence of physical and mechanical properties of the eroded soil on the value of the flow rate of solid runoff is insignificant, and they may not be taken into account. Calculations have been carried out using formulas known from river hydraulics, which show that none of them gives sufficient convergence with experimental data. Based on the analysis of a large number of experimental data, a formula for the discharge of solid runoff for erosion conditions of dam models during overflow has been obtained in the paper. This has taken into account the fact that the dam erosion by the overflow has a high degree of stochasticity and is difficult to describe theoretically. This is especially evident in conditions of spatial erosion, when, simultaneously with the classical erosion of the bottom, the sides of the eroded hole periodically collapse, which is difficult to take into account in the calculations.

Metro Service has a huge impact on the development of urban transport infrastructure. The need to increase the efficiency of passenger transportation is caused by the rapid growth in passenger turnover as well as an increase in the distance from the outskirts of the city to the center. In connection with the need to develop a metro service network in Minsk city, which is confirmed by research in the area of passenger traffic in the main areas of the city, the CSM Bessac tunnel boring machine was purchased, which allows significantly to increase the speed of tunnel driving. The use of a mechanized tunnel boring machine in the traditional concept of the metro network construction, in which driving of tunnels is carried out after construction of stations, does not allow to use a shield with maximum economic efficiency due to the small extent of tunnels. There is also a need to build assembly-shield chambers and carry out works on disassembling and assembling the shield. The application of the new concept developed by Yu. S. Frolov and called “through driving” is actual in the conditions of the use of a mechanized tunnel boring machine. Its essence lies in the continuous driving of tunnels on the line section under construction and the consecutive construction of each station complex as the tunnel boring machine passes through it. To implement the concept of “through driving”, it is relevant to use a semi-closed construction method, in which the floor structure is constructed in an open way, and the other elements are closed. The available solutions of the metro stations constructed while using a semi-closed method of work have been analyzed in the paper. A detailed analysis has been carried out with due account of the adaptation to the construction conditions in Minsk, and the development of structural elements and assemblies of the platform area of the station, which is a two-cantilever vault with a developed transom part, resting on pile-columns of a circular cross section. Forces from the open ring of flexible tunnels lining are supported by a cantilever part of an arch and a bottom plate. The paper considers a design of a metro station, its main elements, their purpose and specificity of work, as well as optimization issues and the results of the design feasibility study.

The paper provides a brief review of the literature on the theory and methods of calculating hinged-connected or articulated structures on an elastic base. The author refers to the works of B. G. Korenev, G. Ya. Popov, I. A. Simvulidi, R. V. Serebryany, A. G. Yuriev, in which, using various approaches, studies have been carried out to calculate hinged-connected beams and slabs on an elastic base. From the analysis of scientific literature on the topic under consideration, it can be concluded that there is no general approach to solving this problem, which is valid for any hinged-connected beams and plates lying on any model of an elastic base under the action of an arbitrary external load. In addition, a similar problem for this type of engineering calculations is observed in the normative documents. In the Republic of Belarus, a number of industry documents have been used to calculate pavement bearing elements for various highways and track transverse structures, in which road pavements with a load-bearing element and the connection of elements between themselves (hinged or rigid) are considered in an incoherent formulation. The paper proposes a universal approach for calculating hinged-connected beams on an elastic foundation, based on the mixed method of structural mechanics, taking into account the Zhemochkin ratios for functions of the elastic medium effects. The following hypotheses and assumptions are taken into account: only normal stresses act on the contact of the beam with the base, hypotheses of the bending theory are valid for beams, hinges between the beams are cylindrical, and the distribution of contact stresses along the width of the beams is uniform. As a result of the proposed calculation, the stress-strain state of a system of hinged-connected beams on an elastic foundation has been investigated, namely: distribution of contact stresses under beams, internal forces in the beams and hinged joints, as well as settlements of the elastic foundation under them. The numerical implementation of this approach has been performed using the mathematical package Mathematica 10.4. Examples of calculation are given for different versions of hinged-connected beams and an elastic base: for three hinged-connected beams based on Winkler and seven – on an elastic half-space.

In this paper, we propose to use a discrete wavelet transform with a singular wavelet to isolate the periodic component from the signal. Traditionally, it is assumed that the validity condition must be met for a basic wavelet (the average value of the wavelet is zero). For singular wavelets, the validity condition is not met. As a singular wavelet, you can use the Delta-shaped functions, which are involved in the estimates of Parzen-Rosenblatt, Nadaraya-Watson. Using singular value of a wavelet is determined by the discrete wavelet transform. This transformation was studied earlier for the continuous case. Theoretical estimates of the convergence rate of the sum of wavelet transformations were obtained; various variants were proposed and a theoretical justification was given for the use of the singular wavelet method; sufficient conditions for uniform convergence of the sum of wavelet transformations were formulated. It is shown that the wavelet transform can be used to solve the problem of nonparametric approximation of the function. Singular wavelet decomposition is a new method and there are currently no examples of its application to solving applied problems. This paper analyzes the possibilities of the singular wavelet method. It is assumed that in some cases a slow and fast component can be distinguished from the signal, and this hypothesis is confirmed by the numerical solution of the real problem. A similar analysis is performed using a parametric regression equation, which allows you to select the periodic component of the signal. Comparison of the calculation results confirms that nonparametric approximation based on singular wavelets and the application of parametric regression can lead to similar results.

The method of correlation measurement of the coolant flow rate, widely used for operational diagnostics of nuclear power plants, can be extensively used in research practice. The aim of this work was to apply a correlation method based on the conductometric measurement system with wire-mesh sensors for measuring a coolant flow rate.Insignificant concentration of a salt solution (NaCl or Na2SO4 ) creates a gradient of the conductivity in the flow, which is used as a passive scalar measured by the system. Authors used turbulent pulsations at the interface of two concurrent flows with identical velocities in a square channel as a signal source for the correlation method. The paper presents the methodology of the tests, test facility description, signalto-noise ratio estimation, the results of digital signal processing and comparison of the measured velocities in the model with the flowrate‒averaged velocity determined by the use of flowmeters. The measured velocity values give acceptable agreement for the turbulent flow modes. It was shown that the measurement accuracy drops sharply for low-Reynolds flows.The obtained results were used for flowrate measurements in core-imitator channels of the nuclear reactor test model. The presented paper is an approbation of this approach for its application as part of an test model of a nuclear reactor in order to determine the each duct flow rates in the channels of the core simulator using wire mesh sensors.

Addition is one of the timing critical operations in most of modern processing units. For decades, extensive research has been done devoted to designing higher speed and less complex adder architectures, and to developing advanced adder implementation technologies. Decision diagrams are a promising approach to the efficient many-bit adder design. Since traditional binary decision diagrams does not match perfectly with the task of modelling adder architectures, other types of diagram were proposed. If-decision diagrams provide a parallel many-bit adder model with the time complexity of Ο(log2n) and area complexity of Ο(n×log2n). The paper propose a technique, which produces adder diagrams with such properties by systematically cutting the diagram’s longest paths. The if-diagram based adders are competitive to the known efficient Brent-Kung adder and its numerous modifications. We propose a blocked structure of the parallel if-diagram-based adders, and introduce an adder table representation, which is capable of systematic producing if-diagram of any bit-width. The representation supports an efficient mapping of the adder diagrams to VHDL-modules at structural and dataflow levels. The paper also shows how to perform the adder space exploration depending on the circuit fan-out. FPGA-based synthesis results and case-study comparisons of the if-diagram-based adders to the Brent-Kung and majority-invertor gate adders show that the new adder architecture leads to faster and smaller digital circuits.

A large variety of machine operating conditions leads to a difference in the wear rate even for their units being of the same type. Operational time terms of single-type units and machines are not the same, and therefore, numerical expressions of operational reliability will be probabilistic values. Incomplete restoration of original properties of a unit, a negligent repair, a poor maintenance usually lead to the fact that any of several parts independently one from another can determine reliability of a machine (a unit). This is especially important to consider when manufacturing packaging in order to avoid rejects. The operational reliability of modern machines consisting of hundreds, and sometimes thousands of parts, wear processes of which are in a complex relationship, depends on a number of factors. A study on reliability of main components and equipment devices is an urgent task. Successful operation of printing equipment is possible only if there is a clear organization of preventive work, ensuring preparation of printing machines for printing and post-printing processing. High-performance equipment, such as die-cutting presses, should be regularly inspected, adjusted and maintained in such a way as to obtain standard results at the output. The paper has studied reliability of main components and devices of die-cutting presses based on calculation of failure probability. Calculations have been carried out by analogy with the calculation of the probability of events in the fault tree. Failure diagrams of devices and units of die-cutting presses have been built in the paper. Based on the analysis of the failure probability for main components and devices, graphs of residual life for equipment operation on its life cycle have been constructed in the paper.

Studies on the influence of applying various technologies for combustion knock reduction have been presented in the paper. Among others, investigation concerning the following: over-expanded cycle, variable valve timing, internal and exhaust gas recirculation, leaning the combustible mixture and cooling the in-cylinder charge were of the interest. The research works were focused on impact of these technologies on both knock intensity reduction, and engine performance and toxic emissions. Results presented in the paper were coming from experimental investigation based on in-cylinder combustion pressure data acquisition. Additionally, knock intensity calculation methods were discussed. They are based on incylinder combustion pressure pulsations. Combustion knock intensity expressed by the maximum peak of the incylinder pressure pulsations shows a strong negative correlation with both the EGR ratio and relative equivalence ratio – lambda. With respect to a catalytic converter installed on the exhaust pipe line, applying EGR appears as better solution for knock reduction then leaning the combustible mixture because the catalytic converter needs stoichiometric mixture for effective NOx reduction. Furthermore, application of the over-expanded cycle to the hydrogen or coke gas fueled IC engine significantly reduces intensity of potential knock by 50 % in comparison to Otto cycle for all loads. Additionally, over-expanded cycle contributes to increase in engine thermal efficiency. Summing up, all the presented measures and technologies can be successfully implemented into practice in stationary engines as well as in traction engines, both of them working on either natural gas or gaseous renewable fuels.

An experimental assessment has been made of the influence of electro-erosive modification modes for worn working surface of an cutter on the restoration of its cutting ability. The paper provides basic information on dental cutters. The provisions of the experimental research methodology are described, including a description of a device for modifying the worn surface of a dental cutter and a device for determining its cutting ability. Experimental data are presented and analyzed that reflect an effect on restoration of a cutting ability of a worn surface of a dental cutter, voltage of a storage capacitor and number of holes applied to it during its modification. Rational modes of modifying a worn-out surface of a dental mill that provide the greatest recovery of its cutting ability have been determined in the paper. It has been shown that with increasing voltage, the energy of the electric discharge acting on the treated surface increases, which leads to the formation of a single hole of a larger size on it, including metal flows along its edge that extend beyond the initial contour of the worn cutter teeth. These metal flows on the modified surface of the cutter play the role of peculiar cutting and deforming elements. It has been revealed that in the process of modifying the worn surface of the cutter, it is necessary to ensure that there is no overlap of the holes formed on it, i.e. the distance between the centers of adjacent holes should be greater than or equal to the size of metal deposits at their edges. In this case, the metal flows retain their original shape and have the highest height at these pulse parameters, which ensures a higher cutting ability of the modified cutter surface than when the holes are overlapped.

The paper presents characteristics of the known classifications of surface shaping methods in mechanical engineering during mechanical and physical-technical processing; according to the classifications a surface shaping method is considered as a combination of methods for generating its producing lines – generatrix and guide – provided that the generation rate of the generatrix is higher than the guide. The advantages of constructing a classification and a formalized description of surface shaping methods have been shown in the paper; each of them represents a combination of surface formation methods in cross section and in length, regardless of generation speed for generatrix and guide lines. This increases information content of the description for a shaping method which is important for comparing methods of shaping surfaces and synthesis of schemes for their processing in the functional design of the machine. The paper has revealed the fact that in comparison with the well-known classification of A. A. Fedotenka it is an expedient to introduce methods of bending, intermittent track and intermittent rolling, as well as combined methods combining advantages of their basic methods which expand the synthesis of progressive processing schemes for profile surfaces. The introduction of the methods has been made in many basic methods of generating production lines (copying, following, touching and rolling). Based on the expanded set of basic methods and the accepted principle of presenting the methods of shaping profile surfaces, their classification has been developed as the basis for systematization and synthesis of known and possible shaping methods. The paper considers examples of rational shaping method synthesis based on the proposed classification and progressive processing schemes for profile moment-transmitting surfaces on the basis of synthesis examples. In particular, the use of an envelope method instead of the applied rolling method has made it possible to simplify significantly a tool design, to increase its versatility and accuracy in formation of moment-transmitting surfaces with a profile in the form of a Relo triangle.

It has been substantiated that in order to control the process of forming flat surfaces while using a free grinding method it is advisable to choose such machine setup parameters as a tool diameter and its rotation frequency, an amplitude of the reciprocating movement of the part along the tool (or vice versa) and frequency of this movement, as well as the value of the working force. Mathematical modeling of patterns for abrasive processing of flat surfaces in the conditions of free grinding on lever machines has been carried out in the paper. A formula has been obtained for calculating a sliding speed at selected reference points on the surface to be treated while taking into account the pressure in their vicinity. Patterns of the part operation have been determined, for which a correct plate is used in the proposed axicon production technology with due account of the combination and size of the selected setup parameters for processing equipment. Self-organization of the processing process has been substantiated while using a free grinding method. Sensitivity of a kinematic response to a change in processing modes and efficiency of these modes in terms of process performance have been determined in the paper. It has been noted that an increase in a tool diameter, as one of the effective adjustment parameters for controlling the shaping process, is difficult to implement in practice, since this requires replacement of tools, each of which must be pre-configured while using a special rather time-consuming technique. The paper reveals that with an increase in the tool rotation frequency and an amplitude of its oscillatory movements, there is an increased removal of material on the periphery of the surface being machined, and with an increase in vibrational movements, on the contrary, the central zone of the part is more intensively activated.

Hot cavity ion sources of different kinds are widely used in nuclear and mass spectroscopy, especially in on-line isotope separation devices attracting attention of scientists and engineers looking for high ionization efficiency, robustness and beam purity. In the paper a new type of hot ionizer cavity is proposed: namely cavity having the shape of a flat disc, which may be especially suitable for short-lived nuclides to be ionized.A numerical model of the ion source is presented in the paper. The particle tracking code takes into account ionization at hot surfaces and enables modeling of both flat disc cavity and standard elongated cavity ionizers. The code enables calculation of total ionization efficiency and is suitable for stable and long-lived nuclides.Influence of the flat disc cavity geometry (thickness and radius) and its temperature on total ionization efficiency was considered – it was shown that the efficiency increases with cavity radius due to the growing number of particle-wall collisions. This effect may be important in the case of the hard-to-ionize nuclides.The optimal ionizer geometry is characterized by 90 % efficiency, even for substances with rather low ionization coefficient (of order 0.05). The role played by the size of the extraction opening is explained – it is demonstrated that the ionization efficiency increases due to the opening radius reduction. It is also proven that extraction voltage of 1–2 kV is sufficient to maintain optimal ionizer efficiency.

Waste of combined heat and power plants represents a certain danger to the environment, and hence the economic problems. However such waste contains substances that are advisable to use for production of construction and finishing materials. Technogenic products of water treatment from the Yuzhnaya combined heat and power plant (sludges of chemical water treatment – code 8410500) are a calcite mixture containing more than 64 wt. % calcite. The mineralogical composition of inorganic waste has been determined while using X-ray and IR-spectral researches. Mechanical activation of calcite inorganic wastes leads to grinding of calcite and a decrease in the amount of adsorbed water, which affects the increase in the content of silica frame structures, the reactivity of which directly depends on their quantity. Changes in the structure of silicon dioxide during mechanical activation are established according to IR studies. The results of X-ray and IR studies of the Zapolie deposit clay used in ceramic brick production technology make it possible to attribute it to raw materials with high reactivity. An experimental batch of ceramic bricks has been produced at JSC “Obolsky Ceramic Plant” with addition of calcite inorganic waste from combined heat and power plants. An X-ray diffraction analysis of samples of the obtained bricks having standard composition and with addition of waste has been carried out. The influence of calcite inorganic waste content in the feedstock on the process of ceramic brick structure formation has been stu-died in the paper. Addition of chemical water treatment waste containing calcium carbonate up to 15 wt. % to the Zapolye clay mixture helps to reduce a firing temperature and an appearance of the melt. This leads to crystallization processes of solid minerals from the melt and an increase in the amount of glass phase which contributes to improvement of strength properties in ceramic bricks. The possibility of using inorganic waste (sludges of chemical water treatment – code 8410500) of combined heat and power plants as a component of emaciated additives in clay raw materials in the process of ceramic brick production has been established in the paper.

The paper considers spatial organization of energy facilities with an emphasis on modern practice of the Republic of Belarus. The efficiency of enterprise operation in any industry including power industry is largely due to their architectural and planning organization. Knowledge of mechanisms and specific features of the changes taking place here makes it possible to justify a promising strategy for project activities, and therefore, it allows to manage development processes of the industry and thereby avoid many negative consequences. Energy facilities are a typological unit of industrial architecture, their formation has been started due to transition of industrial production to electric energy. Today the typology shows functional approach in architectural shaping, it includes a fairly large variety of constituent units and demonstrates a tendency towards diversification. In Belarus energy facilities in the architectural aspect of their classification are limited mostly to thermal power plants operating on different types of fuel. Currently the diversification is developing in the following areas: construction of hydropower facilities (small plants on reservoirs, medium power plants, low-pressure plants, run-of-the-river hydraulic power stations), alternative energy (wind power stations, photovoltaic power stations and biogas plants) and conventional energy (thermal power plant, mini-combined heat and power plant operating on renewable fuel). The results of Belarusian practice in construction of all types of facilities (hydropower, alternative and conventional energy), peculiarities of the architectural and planning organization of facilities at the current stage, correlation with global trends in the development of industrial architecture have been characterized in the paper. The paper has determined typological features of alternative energy facility architecture, opportunities and directions for implementation of architectural approaches, problems and prospects to develop scientific support for the project process.