The article aims to establish the effect of preventive deformation on the accuracy of aircraft parts made from the thermally hardened aluminium alloy 1933T2, after blasting hardening. Determination of the impact of preventive deformation was carried out by analysing structural parts of the "wall" type produced using various technological sequences. Sample 1 was produced using a standard manufacturing sequence: milling – blasting hardening – blasting correction. Sample 2 was produced as follows: milling – preventive deformation – hardening – blasting correction. The deformation of the samples was determined at checkpoints by deviations from flatness based on bending deflections. In sample 2, preventive deformation was performed on its ridges by a rolling device. The calculation of the technological parameters of the rolling device was conducted following the principle of superposition of individual operations, such as rolling and blasting hardening. The definition of the parameters of preventive deformation of sample 2 was based on the results ob tained for sample 1. It was established that, for both samples, the deviation from flatness after milling comprised 2.5 mm. The maximum deviation of sample 1 (without preventive deformation) after blasting hardening was 2.6 mm under a high degree of surface saturation. The maximum deviation of sample 2 (with preventive deformation) after blasting hardening did not exceed 0.4 mm, which corresponds to the acceptable deviation of such structural parts. Thus, the inclusion of the preventive deformation stage in the manufacturing process, with consideration of the deviations resulting from the milling stage, allows minimisation of deviations from the required form after blasting hardening. An analysis of the obtained re[1]sults confirmed that preventive deformation of structural parts reduces distortions after blasting hardening. Therefore, it is advisable to use the following manufacturing sequence: preventive deformation → hardening by a blasting method → correction by a blasting method.

 The aim was to develop a methodology for monitoring the dynamic state of the links “machine tool – device – cutting tool – detail” comprising a cutting technological system as applied to turning specialized stainless steels using replaceable standard hardmetal inserts. The research object was the hard-to-treat non-corrosive stainless steels 09Х17Н7Ю, 12Х18Н10Т and 13Х15Н5 АМ-3. Monitoring was carried out by simulating plate coatings in the Deform software environment. The diagnostic criterion was the tool life period up to the wear level of 0.5 mm along the rear edge. The effect of coatings on the tool life period was assessed according to the following parameters: temperature in the cutting zone, tension in the tool material and tool deformation. As a result, 10 optimal coatings having the greatest impact on the state of the cutting technological system under study were selected. These coatings can be used for diagnosing the state of cutting technological systems. The coatings were distinguished in terms of architecture (design, composition,structure and coating method). A technique for monitoring and managing the state of cutting technological systems according to the results of diagnostics was proposed. The deviation of the revealed state of the cutting technological system from the desired state was estimated by the life period of tools with different coatings for the same time of their operation. The state of the system under study was considered effective provided that the maximum tool life period due to the use of an optimal coating was achieved. A technique allowing assessment of the state of technological cutting systems by their simulation according to the parameters “temperature in the cutting zone”, “tension in the tool material” and “tool deformation” was proposed. This technique also permits monitoring of the state of cutting systems by the parameter "tool life period" and managing their state according to the results of diagnostics through the use of the most optimal plate coatings. The developed technique can be used to reveal the optimal parameters of the cutting mode of hard-to-treat specialized corrosion-resistant steels.  

The article aims to develop a methodology to ensure timely determination of the margins of static aperiodic stability in power supply systems, at the nodal points of which distributed generation units are installed. The authors used mathematical methods and algorithms based on the application of limiting regime equations. Transitional processes were analysed for various points in the space of controlled mode parameters according to the simulation modelling in Matlab using the Simulink and SimPowerSystems packages. On the basis of the obtained results, an effective technique for analysing stability margins in electrical networks with distributed generation units was implemented. This method is applicable in design problems, as well as in operational and emergency control. The conducted theoretical analysis and computer modelling showed the effectiveness of the proposed methodology for calculating stability margins; the nondegeneracy of the Jacobi matrix of limiting regime equations at the solution point ensures the guaranteed reliability of the results. It was shown that an alternative approach to solving the problem of timely determination of aperiodic stability margins can be implemented on the basis of limiting regime equation with increased nonlinearity. Dynamic modelling of an electrical network with distributed generation units confirmed the correctness of determining the stability margins calculated using limiting regime equations. The developed technique can be recommended for practical use in the design of power supply systems or in operational control of synchronous generators. In particular, the presented methodology can be used to implement a multi-agent emergency control system for distributed generation installations located in generalpurpose distribution electrical networks. 

The article aims to identify patterns in the distribution of heating energy to consumers with a varying availability of regulation equipment under real conditions of a central heating network, as well as to compare the results of computer simulation with full-scale measurements. For computer simulation, well-known mathematical methods for calculating the load flow in hydraulic circuits were used. Experimental studies of the operation modes of heat supply systems were carried out using the data of the control and monitoring systems of thermal power plants using the Siemens Simatic PCS7 software, a Portaflow 300 ultrasonic flow meter, stationary electromagnetic flow transducers, verified and certified manometers and thermometers. The graphs of the actual hydrodynamic modes of the heating network under study were obtained at outdoor air temperatures from +8 to -37°C, as well as under abnormal conditions (temperature drop in the supply pipeline and pressure drop at the heating network input). It was proposed to use jointly the simulation by means of the JA_Net software and full-scale measurements of the thermohydraulic operating modes of a centralised heat supply system, whose consumers have a various degree of regulation equipment. It was shown that the proposed complex method of qualitative and quantitative assessment of the efficiency of district heating networks makes it possible to identify the features of control of their hydraulic modes when connecting new consumers with a varying degree of automation. According to the obtained characteristics of changes in the flow rate of the coolant in the consumers’ internal systems depending on the pressure drop at the tie-in point, the lack of response to emergency situations on part of the consumers whose heat supply systems are equipped with the means of qualitative and quantitative regulation of the heat load, is associated with the process of automatic adjustment of the degree of opening of flow controllers and control valves at individual points. In future work, we will develop guidelines for levelling the imbalance of the heating network under the conditions of uneven provision of facilities with automation equipment when implementing projects for the complex modernisation of heat consumers or connecting new facilities to existing heat supply networks. 

The aim was to determine the reliability indicators of a power supply system using an artificial neural network model. A model for calculating technical reliability was developed using the following methods: an algorithm for calculating reliability indicators of power supply systems, the method of failure rate of a power supply system and a forecasting model using artificial neural networks. It was established that a power supply system is formed by an open radial power supply circuit. The failure rate of the power supply subsystem was determined by calculating the failure rate of i-th element of the subsystem. As a result of calculating the probability of failure-free operation of the subsystem for various conditions (5 time intervals), it was found that with an increase in the operating time from 100 to 500 h, a linear increase in the rate of system failures occurs from 0.0051 to 0.0073 1/h. A comparison of the obtained mean-to-failure values of the main and the same backup subsystem in the unloaded mode with an absolutely reliable switch (269.62 h) with the main and the same backup subsystem in the loaded mode (202.21 h) was carried out. The results differ by 67.41 h, which indicates a higher degree of reliability of the first method. The software package Prognoz_INS_2020 was developed. An acceptable accuracy of no more than 2.17% was obtained by comparing the results of the conventional calculation of the failure rate of power supply systems and using the Prognoz_INS_2020 software package. This indicates the efficiency of the proposed software package in reliability calculations at operating energy enterprises. The proposed methods for assessing technical reliability both using the conventional model and a model based on an artificial neural network made it possible to assess the state of power supply systems, which helps to prevent dangerous emergencies. 

The article aims to develop a set of objective criteria for assessing the state of energy security in decentralised remote regions of the north, Arctic zones and autonomous energy supply complexes. The authors assessed the potential of renewable energetics, which determines the effectiveness of decentralised energy complexes based on renewable energy sources, in improving the energy security of such entities. The indicators for assessing the energy security of research objects were developed on the basis of an analysis of the ratio of the most significant threats, as well as territorial and situational factors of the autonomous energy of the north and Arctic zones. A study of the security of the research objects allowed the development of a set of criteria for territorial segments and autonomous electrification objects, forming an objective assessment of the energy security of isolated hard-to-reach areas. An analysis of the possibilities of renewable energy sources in achieving certain positions (resource sufficiency, environmental acceptability, technological attainability and reliability) of the energy security of the considered level was conducted. Groups of properties and processes within the territorial framework of a decentralised region, separated by the directions of monitoring the energy security of local energy zones are proposed as objects of indicative analysis. The differentiation of the developed criteria by the levels of the energy zone and decentralised energy complex allowed consideration of all the specific features of these objects and cover the factors of mutual influence with accompanying systems in the formation of the state of energy security. When considering a possible option for the participation of renewable energy sources in the structural and resource provision of autonomous electricity supply, it was found that such diversification will affect both the improvement of some criteria of energy security of the considered level, as well as the deterioration of others. 

 The author aimed to develop an analytical solution to the problem of the load flow of a six-, eleven- and twelve-circuit heat network, as well as to solve the problem of optimisation of a multi-circuit heat network, including the choice of the objective function and the determination of a number of variable technical parameters. For accelerating the optimisation process, the method of decomposition of the heat network graph was used. Decomposition involves is cutting the network graph at some nodes for the transition of a multi-circuit scheme to a branched scheme in the form of a tree. Optimisation of each branched circuit was carried out by the dynamic programming method, as a result of which new values of the variable parameters were obtained at the current iteration. Next, the author returned to the multi-circuit scheme to solve the load flow problem and calculate the value of the objective function. The iterative convergence of the decomposition method was not mathematically proven. The author proposed a method for splitting the graph, which eliminates the decomposition procedure when optimising a heat network. The following methods were applied: mathematical modelling of the hydraulic circuit, graph splitting method and the analytical method for solving the algebraic equation of the fourth degree. The following results were achieved: a scheme of the minimum element of a multi-circuit heat network was determined, the possibility of series and parallel circuits of minimum elements was shown, and analytical dependencies for the problem of load flow of a heat network of these schemes were obtained. The proposed analytical solution of the load flow problem for a multi-circuit heat network allows the problem of calculating a complex network to be reduced to the calculation of several minimum elements, which significantly reduces the amount of computational work when modelling a hydraulic circuit. The provided examples show that the calculation error does not exceed 3%. 

 In this article, we review existing approaches to recycling technogenic raw materials (ore dumps, metallurgical production slag, mill tailings of ore-dressing plants, etc.), containing non-ferrous and noble metals, which are accumulated in almost non-ferrous metallurgy industries. An analysis of existing technologies for processing technogenic raw materials (pyrite cinders and flotation tailings of concentration plants), which include enrichment, pyro- and hydrometallurgical and combined ways of extracting valuable components, was conducted on the basis of a review of published sources. It was shown that enrichment (screening, desliming in a hydrocyclone, enrichment using a concentration table, magneticliquid separation, flotation), pyrometallurgical and combined ways for extracting noble metals from this type of raw materials are unprofitable. The most satisfactory results were obtained using hydrometallurgical methods to extract valuable components from technogenic raw materials. Various solvents, such as sodium cyanide, thiocarbamide, sodium thiosulphate and sodium sulphite were tested as leaching agents. Cyanation proved to be the most effective way to extract noble metals from technogenic raw materials; however, this process is characterised by a high consumption of sodium cyanide. Therefore, it is of importance to discover an approach to extracting valuable components from such problematic products in order to make their processing more cost-effective by reducing cyanide consumption while maintaining gold extraction. According to the obtained results, gold-containing raw materials are promising in terms of extraction of nonferrous and noble metals using hydrometallurgical technologies. Future research should identify rational methods for processing technogenic gold-containing raw materials in order to make the technology more profitable for extracting valuable components. 

 The aim was to investigate the mechanism of passivation of polycrystalline cathodes and to justify experimentally the possibility of stable electrolysis when using solid electrodes. Under laboratory conditions, the mechanism of electrode passivation and the conditions for stable electrolysis were experimentally studied. To this end, the methods of X-ray phase analysis and electron-microscopic examination of the spent electrodes were employed. A study of the electrolysis of cryolite-alumina melts showed that, in the presence of surface micro- and microdefects on a solid cathode, a precipitate consisting of impurities and electrolyte components was gradually formed. Under the selected experimental conditions, the surface of carbon cathodes was passivated with a dense double-layer precipitate of CaB6 and electrolyte components. Using the example of a carbon cathode containing both metallic titanium and titanium oxides, a method for eliminating surface microdefects is presented. This method consists in electrochemical borating of a carbon-titanium cathode. The conducted spectral electron microscopic and energy-dispersive analysis found that, during a 45-hour laboratory experiment at 980 °C and under a current density of 0.7 A/cm2, the inhomogeneous surface of the cathode was homogenized with a titanium diboride layer. At stable electrolysis parameters, an aluminum layer is electrodeposited on the cathode. A complex analysis of the electrolysis conditions, the appearance of the initial and spent carbon cathodes, and the data of analytical studies confirmed that micro- and macrodefects of the electrode cause the formation of a dense layer of deposits on the cathode. The established mechanism of passivation of a carbon cathode as a polycrystalline product can be applied to all composite electrodes, including those based on titanium diboride. A logical condition for the practical application of solid cathodes is the development of an electrolysis process with continuous surface reconditioning to decrease the chemical inhomogeneity and microdefects of the surface across the entire technological sequence. 

 This article presents a research study in the field of formation and implementation of Russian oil and gas policy, which has a decisive role in the development and functioning of the country's energy sector, its energy security, as well as for increasing revenues.  The current relations between actors in the European gas market, which is expected to remain an important sector in Russian economy in the medium term, are assessed in the contexts of the risks and threats experienced by gas exporters. The role and place of the Russian Federation in gas export to China as an important element of the Russian Eastern Gas Policy and Energy Security Doctrine is discussed. Following an analysis of information from official sources, research publications and reports presented in the mass media, a substantiation of the urgency of the problem and the directions of its solution is given. The conducted study revealed that the oil and gas sector in Russia remains the most important component of the country's fuel and energy complex. Stable export of oil and gas is key for the oil and gas industry, contributing to the country's energy security. It is noted that, in the medium term, Russia will preserve at least 30% of the European gas market. At the same time, the energy policy of the European Union, anti-Russian economic sanctions and the excess of gas supply over demand are forcing Russia to significantly reduce the cost of exported gas in order to maintain its segment in the European gas market. The forecasted risks and threats to the "western vector" of the Russian gas policy determine the necessity to diversify gas export markets. In this regard, it seems reasonable to implement of the "Eastern Gas Policy" as an element of the energy strategy in the eastern regions, aimed at the widespread use of natural gas for domestic needs and export supplies. The emerging strategic partnership with China is determined not only by the energy partnership, which is acquiring new initiatives, but is also characterised by a wider sphere of relations, including economic and political cooperation. At the same time, economic cooperation in the gas sector is aimed primarily at ensuring the possibility of diversifying gas supplies to Chinese regions having a developed demand.  In the current financial and economic situation in the energy market in the western direction, Russia is often forced to accept China’s conditions. The research results demonstrate that the Russian oil and gas complex retains key positions in the country's energy sector and economy. Currently, the process of active spatial development of the fuel and energy complex in the East of the country is observed, while in the long run both the “western” and “eastern” vectors of Russia's gas policy remain. Strengthening trade, economic and political cooperation between Russia and China in the medium and long term will lead to a significant increase in energy cooperation on mutually beneficial conditions.