The paper considers the influence of the parameters of the plasma spraying process on the technological characteristics of multilayer coatings based on nickel-chromium, nickel-chromium-aluminum-yttrium materials, oxide ceramics,  intended for operation at high temperature and additional dynamic loads. The design of plasma coatings during their application (with subsequent high-energy processing) under such conditions requires a comprehensive solution – both the use  of high-quality powder ingredients and the optimization of technological parameters. The plasma process of applying powder materials has been improved to obtain the maximum values of their utilization factors. The technological characteristics that affect the properties of plasma coatings are optimized, namely: the flow rates of the plasma-forming and materials-transporting gases, the flow rate of  supplied powder materials, the current and voltage of the electric arc of the plasma torch, the distance from the plasma torch nozzle exit to the substrate. The paper presents the results of studies of the structure  of coatings, performed using scanning electron microscopy. Their analysis has made it possible to form general regularities obtained by the action of radiation of compression plasma flows on coatings formed by air plasma. The considered structures are created using the processes of melting, compaction and high-speed cooling of plasma coatings. The main optimization indicators are the maximum local compaction and spillage of the obtained compositions with the absence of defects and  destruction from the impact of compression plasma flows. The main effect during the action of radiation of a compression plasma flow on previously formed coatings is thermal. It contributes heating of the near-surface layer. When the coating  is exposed to radiation of compression plasma flows, a remelted layer of oxides with a thickness of about 12–15 µm is created, smoothing the relief of the formed surface and creating a network of cracks on the surface, diverging into the depth of the coating. The liquid-phase processes occurring in the molten phase of the near-surface layers after exposure to compression plasma radiation change the structure of the layers and contribute to the modification of their mechanical properties.  By smoothing the surface, increasing the density of the surface crystallized layer and  minimizing macro-defects – pores  or macrocracks – the mechanical characteristics of the coatings increase.

The development of research in the field of creating a mobile monitoring system for diagnosing the technical condition of mining equipment in terms of mechanical vibration parameters is one of the most science-intensive areas. The paper presents the results of investigations on the possibility of isolating the mechanical vibrations of the handles with a natural frequency  of 5 Hz, which occur with a greater or lesser amplitude in almost all registered spectra, arising from breakages  of cutters on the cutting discs of double-flow drives of the executive body of a mining machine. Therefore, it can be used for operational mobile monitoring of breakages in the cutters of the executive bodies of mining machines. An analysis of vibrations has confirmed the fact that they are transmitted to almost all non-rotating parts of the combine, where they can be registered, which allows them to be used for mobile automated monitoring of cutter breakages on cutting discs. On the example of the combine “Universal-600” it has been found that the most convenient when registering these vibrations from the standpoint of the absence of the need to introduce a signal transmission module from the rotating parts of the combine into the measuring path can be considered the placement of a vibration sensor on the body of the input gearbox of the executive body drive with its orientation in the direction combine movements, where oscillations with a frequency of  5 Hz are prevalent and it is quite simple to isolate them from the low-frequency range using standardized low-frequency one-third octave filters. The paper proposes a technique for creating a system for automated mobile monitoring of cutter breakages based on the parameters of mechanical vibrations of cutting discs with natural frequency. 

In modern mechanical engineering, along with reducing the metal consumption of structures, the main task is  to increase the reliability and durability of parts, assemblies of mechanisms. This problem never loses its relevance due 

to the ever-increasing requirements for manufacture of products, with the need to save scarce expensive metals and alloys and,  as a result, replace them with economically more profitable options. One of the most promising, from the point of view of ecology, ways to replace metals, is to use in the construction of plastic assemblies, in particular polylactic acid (PLA). PLA is a biodegradable thermoplastic used in 3D-printing. The paper presents results of an experimental study on the rupture of samples obtained by 3D-printing from PLA under various technological operating modes of 3D-printer. The following parameters have  been chosen as variable parameters: the form of filling samples (triangle, hexagon (honeycomb), line, edge), nozzle temperature (190–205 °С), sample filling factor (from 10 up to 40 %). Tensile testing of the samples have been carried out on a hydraulic tensile machine with a measuring software package in the Kason WDW-5 set. When performing tests, the conditional yield strength was considered the main out put indicator. The analysis of experimental data has shown a significant effect of the investigated technological parameters on the conventional yield point, which varied from 16.5 to  22.42 MPa. The most rational forms and sample filling factor, as well as the temperature of nozzle when printing with PLA, have been determined.

By usage of the technical and economic calculation method developed by the authors for installations with recuperative-type heat exchangers, the operational modes of the centralized supply and exhaust system of organized ventilation, in which the supplying air is heated by the solar radiation heat and the heat of the air removed from the premises, have been investigated in the paper. The paper presents results of the thermal and economic efficiency assessment of such ventilation system for multi-storey buildings. A comparison of the thermal energy consumption for the needs of heating and ventilation through the use of the proposed ventilation system has been made for two variants of buildings – with the thermal protection level of enclosing structures that meets modern regulatory requirements (buildings with heat consumption up  to 130 kW×h/(m²×year)), and for a building similar in terms of planning structure, but with enclosing structures, the insulation level of which corresponds to buildings built before 1993 (buildings with heat consumption up to 260 kW×h/(m²×year)).  The temperature conditions have been determined under which it becomes necessary to turn on the operation of devices  for additional (peak) heating of the supply air, when the thermal potential of solar radiation and secondary energy resources  is  insufficient to provide the calculated temperature of the supply air. For the ventilation system under consideration, it has been  established that the thermal resistance of the building envelope influences the indicators of the thermodynamic and economic efficiency of the proposed solution. The climatic conditions under which the utilization of the exhaust air heat in the proposed ventilation system is technically justified and economically expedient have been determined. The results of the research 

The paper considers the optimization problem of hinged reinforced concrete rectangular smooth and ribbed slabs. The static calculation of the slabs has been performed while using the finite element method. The model is built from rectangular finite elements containing four nodes each and having twelve degrees of freedom.  The load is presented in the form of nodal vertical forces. To take into account the nonlinearity of the deformation of reinforced concrete, the finite elements 

are taken as inhomogeneous multilayer plates. The modulus of elasticity changed according to the hyperbolic dependence. The determination of the stress-strain state has been carried out by the iterative method. For optimization, a method has been used to reduce resources for strength, stiffness, and crack opening with gradient descent along the boundary of the allowable area. The cost of the material spent on the manufacture of the slab and the volume of concrete are taken as objective functions.  Restrictions on strength, stiffness and width of cracks are set. By scanning, the boundaries of the admissible search area for the optimal solution are set; the boundary of this region has a curvilinear outline. According to the results of the calculation, the trajectories of the search for optimal solution are obtained. Examples are given and optimal solutions are found for various starting points. It has been established that for the accepted conditions of the problem, the extreme points are located near  the boundaries of the admissible region. The speed of gradient descent and the location of the starting points do not significantly affect the results. Due to the fact that the objective function can have several minima, a method is proposed to search for a global minimum by preliminary scanning and analysis of extrema values. It is confirmed that the applied method ensures  the stability of the optimal solution.

The possibility of using cement granulate, a product of processing old cement concrete and waste generated during the demolition of buildings and structures, has been studied in the construction, reconstruction and repair of highways.  The use of recycled materials in the road industry is one of the sources of saving natural raw materials. In addition, the use  of waste solves environmental problems through the disposal of old waste materials and structures. Having completed the study of cement granulate, the possibility of using it for the construction of foundations for road pavements, as well as  a substitute for crushed stone in the manufacture of concrete slabs of prefabricated coverings, has been determined. In the first case of using cement granulate, the wedge method is effective. It has been experimentally confirmed that the remains  

of cement mortar on the surface of used crushed stone contribute to its better wedging, thereby creating a more durable base layer. In order to assess the possibility of using cement granulate as a substitute for crushed stone for the manufacture  of prefabricated concrete slab, standard studies of this material were carried out, the composition of the cement concrete mixture was selected, and standard samples were manufactured and tested. The test results have shown that the use of cement granulate for such purposes is quite acceptable. In particular, the average strength of the samples in the tested batch turned  out to be 45.13 MPa and the guaranteed strength was 35.13 MPa, which corresponds to the B35 class of concrete. These  indicators demonstrate that the use of cement granulate may well be in demand in the construction and reconstruction of local roads. At present, as it is known, a program is being implemented to improve the transport and operational level of local roads, and this is about 70 thousand kilometers. And here, of course, a huge amount of road construction materials will  be required.

The present paper describes experiments and research outcomes concerning the construction of cement concrete pavements in South Kazakhstan, taking into account significant climate changes. The study has identified  potential problems in the construction of cement concrete pavements in the region, where there was no experience of their construction until  the mid-2000s. In order to develop an optimal solution, the technical factors that characterize the process of arranging these coatings using sliding molds are analyzed and quantitatively normalized. These factors include the optimal amount of mortar for curing concrete, the optimal joint cutting time, the interval and effective width of expansion joints to prevent the formation  of cracks in concrete at an early age. The effectiveness of the use of polyethylene film to prevent the formation of contraction cracks and maintain the required mode of hardening of the cement concrete pavement is shown. The main cause of damage  to the expansion joints along the length of the day coverage of coatings in the conditions of South Kazakhstan has been established. Recommendations have been developed for the installation of cement-concrete pavement and expansion joints during the construction of roads in this region. The accumulated data on climatic factors and methods of work with the use of polyethylene film have made it possible to create an optimal method for the construction of cement concrete pavements,  which will improve the quality of roads in South Kazakhstan.

The paper considers options for reducing environmental losses in Polotsk and Novopolotsk through the development of trolleybus and tram systems – various types of urban electric transport. In order to reduce the costs of creating 

transport (including charging) infrastructure, as well as operating costs, the effectiveness of such systems has been determined when using not only classic types of transport, but also hybrid buses, electric buses, duo-buses. Approaches and methods have been developed to improve the quality of passenger service without deteriorating the environmental situation – this will  become possible thanks to the development of tram and trolleybus traffic in Polotsk and Novopolotsk. Variants of scenarios for the use of various types of urban eclectic transport in the cities under study are presented, which will reduce investment  in vehicles and the cost of creating an operational base at the expense of existing production facilities, for example, a tram fleet. In addition, this will make it possible to create and organize a unique agglomeration rail passenger system, which can become one of the ways to develop the tourist potential of Polotsk and Novopolotsk. The proposals outlined in the paper  are aimed at improving the environmental situation in these cities by reducing the volume of emissions of harmful substances by buses, especially on the central streets.

To analyze the synchronization of machine-building production processes, a statistical approach is used on the correctness of the choice of parameters. The accuracy of the parameters is achieved by modeling. This method allows checking how correctly the parameters are selected and whether they ensure uninterrupted operation of production. Statistical analysis of parameters gives information on failures in a particular production unit, on violations of the synchronization of production processes, technological processes. With the help of statistical characteristics, it is possible to evaluate production as a whole. Statistical multidimensional analysis of complex production data allows to analyze the work of individual units, production blocks. The cluster analysis has been carried out by the method of K-medium production process with minimization of the total error probability. A geometric interpretation of the results of cluster analysis of production processes is given in the paper. The influence of  factors on the work of production has been determined in the paper. The index factorial method with  a different comparison base and different weights has been applied. The hypothesis about the adequacy of the model of production processes has been tested. A statistical analysis of the complex data of the production process has been carried out  in the search for optimal solutions in the case of uncertainty and in conditions of risk using the following methods: Bayes, Laplace and Germeyer using the simplex method. The network methods of decision-making have been used in the paper.  Statistical methods  with the help of mathematical modeling have substantiated the optimal sizes of both individual parts  and volumes of local warehouses, so that there were no delays in the transfer of production processes, disruptions in work, downtime of working equipment. In this case, the criterion for the optimality of production volumes can be the minimum  of total losses from idle time of individual units and production blocks to the possibility of disruption of the synchronous  process modes due to lack of equipment (arising production pockets) or due to long-used outdated units.

The main directions of the concept of national strategies for sustainable development are considered, taking into account the problems of energy and resource saving, as well as the need for the rational use of natural and secondary resources in many countries of the world community in order to transition to a “green” economy. An assessment of the energy potential of combustible waste that has not found technological application is given as one of the priority areas in the field of nontraditional energy. The paper presents aspects of research into obtaining and production of multicomponent solid fuels. A technology is described for briquetting wet mixtures with the addition of various binders, including various combustible wastes, in order to obtain solid fuel. The features of the fuel frame formation are given, taking into account the factors affecting the performance of the briquetting plant, as well as achieving the optimal density of the briquette. A qualitative assessment was made with respect to various ratios of the components of briquetted fuel, at which the best production and consumer indicators are achieved. The features of the preparation of materials and the technological equipment used as part of the preparation and briquetting line are considered. The practical aspects of the production, drying, use of briquetted solid fuels are outlined in the paper. The paper presents studies of the energy and physico-chemical characteristics of multicomponent fuel compositions using various research laboratory equipment and methods. The proposed algorithm for solving the problem makes it possible to rationally use substandard combustible production waste to obtain multicomponent solid fuel, while energy and environmental aspects are taken into consideration at the production stage.