The PURPOSE of the study is development of methods and tools for modeling electromagnetic fields when passing a tractive network in artificial constructions of railway transport. METHODS. The study employs the methods for determining the modes of traction power supply systems (TPSS) using phase coordinates, which are based on the models of elements in the form of lattice equivalent circuits with a fully-meshed topology. These models and methods are implemented in the program complex Fazonord providing simulation of the TPSS modes of different types as well as determination of strengths of an electromagnetic field created by tractive networks of these traction power supply systems. When calculating the strengths the elements of artificial constructions have been simulated by the sets of grounded wires. RESULTS. The article presents the simulation results of electromagnetic safety conditions in the traction networks on the sections of railroads located in artificial constructions including galleries, bridges, tunnels. The metal work of these structures significantly affects a distribution pattern of electromagnetic field strengths in space. This fact is explained by the presence of the grounded conducting objects (which transform the tunnels, galleries and bottom-road bridges into limited spaces) and remoteness of the Earth's surface when moving on the deck-type bridges. CONCLUSION. The simulation results of electromagnetic fields in the engineering structures of railway transport show that at the height of 1.8 m from railroad tracks the deck-type bridge has the greatest electric and magnetic fields the strengths of which are higher than in the open space. The tunnel, gallery and the bottom-road bridge are characterized by smaller strengths and lower flows of electromagnetic energy, which is due to the closeness of the screening metal works of these constructions to the catenary system. The energy is transferred by an electromagnetic field in tunnels, on galleries and bottom-road bridges in a limited space between the catenary system and grounded constructions located nearby.

PURPOSE. The paper deals with an upgrading variant of the low-frequency technology of Power Line Communications (PLC) for targeted control of LED lighting in a long-length lighting system. It allows to reduce the influence of transmitted data on the quality indicators of electrical power. METHODS. Today the use of low-frequency PLC technology for data transmission is accompanied with cutting off some separate half-waves of the mains voltage or their parts. This leads to a significant deterioration in the quality of electrical power. To reduce the negative impact on power quality indicators it is suggested to use a data marker in the form of a single period of the mains voltage with a reduced amplitude. The schemes of power switches with artificial commutation have been developed and tested to form such a marker and transfer data. RESULTS AND THEIR DISCUSSION. The results of experimental studies prove the efficiency of the developed power switches and the proposed method of data transmission as well as its partial load effect on the electrical network. CONCLUSIONS. The proposed solutions of power switches have a smaller effect on dimmable power supplies of LED fixtures and on power quality indicators. They can be used both for street dimmable lighting and in the factories where high-frequency PLC technology is prohibited.

The PURPOSE of the paper is to give a computational and experimental rationale for the theoretical model of two-phase liquid-vapor flow through a fixed layer of solid particles, compare the calculation results with the experimental data on subcritical and critical liquid-vapor flow through various beds of spherical particles and estimate the predictive capability of the model. METHODS. Theoretical description relies on the equations of gas dynamics of a granular layer and the homogeneous model of a one-component two-phase flow taking into account the difference in velocities of liquid and vapor phases, which allows to obtain an analytical solution for the mass velocity of the mixture. When obtaining the dependences for the phase slip ratio and the polytropic coefficient for isenthalpic expansion of the mixture multidimensional nonlinear regression methods are used. Methods of the experimental study of liquid-vapor flow in a random packed bed of spherical particles are used to obtain the experimental data on the mass velocity value. RESULTS AND THEIR DISCUSSION. The analytic expression for the mass velocity is obtained in the framework of the presented gas dynamics model of the liquid-vapor flow through the fixed layer of solid particles. The available experimental data on the mass velocity of critical and subcritical flow are generalized using the theoretical model. It is shown that the transition to the relative magnitude of the mass velocity allows to construct a universal flow characteristic for an arbitrary granular layer. CONCLUSIONS. The developed mathematical model can be used to generalize the experimental data and predict the dependence of the mass velocity of a two-phase liquid-vapor flow in a layer of solid particles under subcritical and critical flow regimes.

PURPOSE. The article gives an overview of micro hole drilling methods which have found industrial application in the world mechanical engineering technology. The essence of the methods of mechanical, electrophysical, electrochemical methods of casting, assembly and spraying is described. The technological capabilities of methods, their advantages and disadvantages are shown as well as their comparative characteristics. The application areas of methods are specified in order to determine the most effective method of drilling precision micro holes in terms of ensuring the required hole quality and process performance. METHODS. A comparative scientific and technical analysis of the world industrial technologies of obtaining micro holes in the historical development forms the methodological basis of the research. RESULTS AND THEIR DISCUSSION. The article gives a physico-technical characteristic of ten methods of micro hole drilling, describes their process capabilities and used equipment. The quantitative and qualitative assessment of technological processes is given as well. CONCLUSIONS. The rational fields have been determined for the application of five methods of micro hole drilling. The promising directions of improving precision micro hole technology have been developed.

PURPOSE. Designing of a rational tool material for the specified operation conditions with the required durability period is difficult due to the lack of appropriate methods. The authors of the article have developed such a method for end milling by carbide-tipped cutters. The value of internal stresses in the cutting wedge of the tool and the distribution nature of these stresses are taken as a parameter having the necessary level of influence on the tool working capacity. Tool coating is accepted as a means influencing the magnitude and nature of stress distribution. The variety of existing architectures of coatings (design, composition, thickness, total thickness and thickness of each layer, etc.) makes it difficult to choose the rational one. Searching for a coating in an experimental approbation is time-consuming and expensive. Therefore, there is the need for computer modeling. METHODS. Using ANSYS software package as a basis for modeling, the stresses is simulated in the cutting wedge of the carbide end mill teeth without coating and with several different coatings. RESULTS AND THEIR DISCUSSION. The most rational tool materials have been experimentally determined by their durability period. They have been compared with the simulated stresses under specified operation conditions. It is found that lower stresses correspond to longer wear resistance periods of the tool. CONCLUSION. By changing the coating architecture in computer simulation of stresses the coatings are selected that provide the required margin of tool wear resistance. They have a 10% excess (40 min) of the specified period of wear resistance. The most technologically convenient coating is chosen from these ones. It is applied to a hard alloy tool tested in real operation conditions. The specified period of wear resistance has exceeded by 8-15%. It is accepted as valid.

A special adjustment of vibration fields is required for vibrational technological processes where loose working medium interacts with the large-size parts being machined, for example, helicopter blades. The PURPOSE of the research is to develop a method for constructing mathematical models ensuring the formation of homogeneous vibrational fields through introducing of additional constraints into systems. The article shows constructive and technical possibilities of implementing such approaches. METHODS. The authors propose an adjustment method for a vibration shaker, the working element of which can perform flat oscillations creating the structure of a uniform vibrational field or the field close to it in certain frequency ranges. The paper uses the methods of structural mathematical modeling and the analytical tools of the theory of automatic control. RESULTS. The article presents the results of the computational experiment. The analytic relations are proposed for adjusting the vibration shaker parameters. CONCLUSIONS. The idea of the developed approach is to introduce the mechanisms in the structure of the vibration shaker as additional constraints that have the potential to change the reduced masses and stiffness of the system. A method for determining system parameters ensuring a homogeneous structure of the vibrational field under the action of two inertial exciters has been developed on the basis of the use of transfer functions of inter-partial ties.

The PURPOSE of the paper is to analyze machine-building industry product quality improvement through the use of digital technologies on example of the technological process of pipe bending. METHODS. The literary sources and research works are reviewed. RESULTS AND THEIR DISCUSSION. Having analyzed pipe bending technologies a method for improving the technological process of pipe bending was proposed using digital technologies including a complex of a CNC pipe bender and a 3D scanner. The application of this method allows to reduce the technological process duration by an average of 16 times, shorten the workpiece length, decrease the reject rate of the technological process of bending pipes. CONCLUSIONS. Development and implementation of new production technologies are important tasks for mechanical engineering. The use of digital technologies enables significant increase in the efficiency of production processes and considerable reduction of the costs of information processing required under the manufacturing of engineering enterprise products.

The PURPOSE of the paper is to determine the stress state and the plastic deformation zone of cylindrical parts under transverse burnishing by flat plates. METHODS. The mathematical apparatus based on the laws of the theory of elastico-plastic solid is used in the work. RESULTS AND THEIR DISCUSSION. We have obtained analytical dependences for the determination of the stress components and the zone of plastic deformation under transverse burnishing by flat plates. The calculation results have shown that there is a stressed state of dilatation in the center of the workpiece cross-section and there is a stressed state of compression in the workpiece shell after the transverse burnishing. The depth of the plastic deformation zone depends on the degree of percentage reduction and the coefficient of friction between the workpiece and the plates. CONCLUSIONS. It is proposed to use the method of transverse burnishing by flat plates to harden low rigid cylindrical parts of the shaft and axle type. The developed mathematical model provides quite reliable values of the stressed state of the plastic deformation zone. The radius of the elastic deformation zone depends on the degree of percentage reduction and the coefficient of friction between the workpiece and the plates when transverse burnishing by flat plates. The hardening method employing transverse burnishing by flat plates eliminates cracking and material breakage in the central region of cylindrical products.

The purpose of the work is to improve the dynamic stability and productivity of hole processing. METHODS. The scientific fundamentals of the technology of mechanical engineering and material cutting, modeling and active experiment form the theoretical basis of research. The experimental data are obtained with the help of measuring means including the program complex based on the Taylor Hobson Form Talysurf i200 profilometer, Carl Zeiss CONTURA G2 coordinate measuring machine, Zoller Genius 3 geometric parameter monitoring device, Kistler 9129AA and 9253B23 dynamometer complexes, CutPro hardware- software complex and others. RESULTS AND THEIR DISCUSSION. The developed mathematical model of the drilling process allows to solve the task of improving productivity, surface quality and accuracy of holes in the parts made of aluminum alloys by choosing optimal cutting conditions on the basis of the dynamic stability diagram. The created mathematical model of hole accuracy dependence on the length of the twist drill working part and the cutting modes enables the prediction of the hole accuracy as early as at the design stage of the technological process. The calculated modal parameters of instrumental adjustment for a solid carbide drill can be used in plotting drilling process stability diagrams. The developed procedure for studying clamping chucks allows to evaluate their effect on the dynamic stability of the drilling process as well as to estimate their effect on the quality and accuracy of produced holes. CONCLUSIONS. Having considered the results of experimental studies, it was proposed to use a hydroplastic chuck when drilling holes with the required accuracy in accordance with H7-H8. The experimentally determined coefficients of the cutting force model allow to take into account the physicomechanical properties of aluminum alloys V95pchT2, 1933T2, 1163T when modeling the drilling process both in special software products and using high-level programming languages.

The PURPOSE of the paper is to study the effect of temperature on the equilibrium states of the system under roasting of sludge/Na₂CO₃ charge. METHODS. The arsenic recovery rate and its yield are determined by arsenic content variation in the initial samples of charge and aqueous leaching cakes. The content of arsenic in dump and cake samples is determined by the x-ray fluorescent method. The phase composition of waste is studied on the XRD-6000 diffractometer. The equilibrium composition of systems is calculated in the computer program HSC Chemistry 6.0. RESULTS AND THEIR DISCUSSION. Having studied the variation rate of arsenic recovery from cobalt production waste under charge roasting within the temperature range of 600-900°C, it was shown that the rate of arsenic recovery (as a soluble product of Na₃AsO₄) is maximum at the temperature of 700-740°C. It has been found out that the temperature influences the equilibrium composition of the system where Na₂CO₃ reacts with ten low soluble arsenates Ca₃(AsO₄)₂, AlAsO₄, Mg₃(AsО₄)₂, Ni₃(AsО₄)₂, Сo₃(AsО₄)₂, Fe₃(AsО₄)₂, Pb₃(AsО₄)₂, Zn₃(AsО₄)₂, Сu₃(AsО₄)₂, FeAsО₄. The chemical equilibriums of reactions of all listed arsenates excluding iron (III) arsenate are shifted towards the Na₃AsO₄ yield in the researched conditions at the temperatures above 600°C. This is due to their endothermic thermal effects (ΔH>0). At the same time, as the temperature grows the depth of the equilibrium shifts weakens due to the decrease in their ΔH values. In the case of FeAsO₄ and Na₂CO₃ interaction the equilibrium shift increases in the direction of the reverse reaction, i.e. consumption of Na₃AsO₄ due to the release of heat (exothermic reaction, ΔH<0) as the temperature grows. CONCLUSIONS. The phase composition of sludge in the waste dumps of recently not operating plant “Tuvacobalt” is represented by calcite, dolomite, quartz, silicates and low soluble arsenates. The latter are transformed into water-soluble Na₃AsO₄ in the process of sludge and soda charge (ratio 1:1) roasting. The rate of arsenic recovery in the form of sodium arsenate increases in the roasting temperature range of 600-740°C. The highest value of the arsenic recovery of 3.33 mg/min, and its maximum recovery degree of 85% (if its content in the charge decreases from ~ 4.0 to 0.7wt %) is detected at the temperatures of 700-740°C.

The PURPOSE of this study is the efficiency test of a domestic depressor reagent under flotation of carbonaceous gold-bearing ores of various deposits. METHODS. Quantitative X-ray fluorescence, phase, atomic absorption, gravimetric and ICP-AES analyzes are used to determine the chemical composition of the ore. The mass fraction of the organic form of carbon is measured by the LecoSC-144 DR determinator. Gold content is determined using the assay-gravimetric analysis. Flotation feed is prepared using the Knelson KC-MD3 centrifugal concentrator. The flotation studies are carried out using gravity tailings and flotation machines of a mechanical type. RESULTS AND THEIR DISCUSSION. The study results show that the use of carbon suppressant reagent in flotation concentration increases the flotation concentrate quality by the gold content, while preserving the recovery level of the valuable component. It also contributes to the reduction in the yield of the flotation concentrate by decreasing the mass fraction of organic carbon and rock-forming minerals of the ore. CONCLUSIONS. The conducted study has found out the domestic reagent to be an effective depressant of a carbonaceous substance under flotation concentration. This fact allows to talk about its prospective use under flotation of carbonaceous gold-bearing ores.

The PURPOSE of the paper is to create an optimal logical algorithm based on functional diagram analysis for the technical diagnosis of industrial frequency converters. METHODS. An analytical criterion of diagnostic algorithm optimality is formulated as a minimality of average costs for determining one technical state of the object of diagnosis. An algorithm is developed for the solution of the problem of finding a sequence of elementary diagnostic tests of industrial frequency converter functional blocks, which satisfies the formulated criterion. The main stages of solving the problem are identified: the analysis of the functional diagram of the device being diagnosed for the expediency of diagnostic tests of functional blocks in various situations; selection of the block to be tested first, determination of tree parts representatives, formation of possible sequences of elementary test execution in configuration branches, identification of sequences characterized by minimum average costs of implementation; synthesis of the configurations of optimal algorithms from previously determined composite parts. The developed procedure is implemented in the high-level programming language Object Pascal by means of Delphi integrated environment. RESULTS AND THEIR DISCUSSION. The paper presents the procedure of configuration construction for the optimal logical algorithm of electrical equipment diagnosis. A specialized application FC_OPTIM has been created in the framework of this procedure program implementation as applied to industrial frequency converters. Two configurations of logical diagnostic algorithms satisfying the criterion of optimality have been constructed. One of the received configurations corresponds to the MPT-algorithm of frequency converter diagnosis developed by the author of the present article. The algorithm is used when structuring the knowledge base of an expert complex for adjusting frequency converters FC3. CONCLUSIONS. An optimal logical algorithm has been developed for the technical diagnosis of industrial frequency converters. It is based on the analysis of the functional diagram.

PURPOSE. The processes of radical polymerization of methyl methacrylate are subjected to a strong gel effect and in this connection the polymerization process is carried out at a relatively low temperature and a high ratio of a monomer and water, which negatively affects the productivity of reactors. The purpose of this publication is to study the dynamic features of a typical industrial reactor under various process conditions for the further development of a control system for such reactor. METHODS. In order to obtain the transfer function of the control object our previous work provided a mathematical description of the reactor in the form of a system of differential equations of heat balance and a structural diagram of the control object. Using Mathcad and MATLAB Simulink, this article shows the variation ranges of all parameters of the control object depending on the degree of monomer conversion under different flow conditions of the process. RESULTS. A family of transient response curves of the control object is obtained under different flow conditions of the process. CONCLUSIONS. The obtained results correspond to the real data of polymethyl methacrylate production at industrial enterprises.

The PURPOSE of the study is to compare the software tools for the computer-assisted construction of simulation models. METHODS. The main research methods include system analysis and methods and technologies for mineral processing. RESULTS. The study is given to the existing programming tools for the automated synthesis of simulation models. The universal means of simulation model synthesis are considered and the characteristic parameters of products are determined. The comparative analysis of universal and unique software tools is given in terms of their application in complex industrial technological processes on example of mineral processing. CONCLUSION. Having analyzed the existing software products engaged in solving the automation problem of simulation modeling and capable of technological production process modelling, we derived a conclusion that versatility is not a key parameter when choosing a software product. The focus should be on the requirements and capabilities of the simulation model user.

PURPOSE. The purpose of the present research is to increase the efficiency of operational prediction of forest fire dynamics under nonstationarity and uncertainty through the development of the operational prediction method based on Artificial Intelligence and Deep Machine Learning. METHODS. The methods of system analysis, neural networks, and deep machine learning are used to solve the set problem. RESULTS AND THEIR DISCUSSION. To ensure the formation of an effective operational prediction in the complex conditions of uncertainty and nonstationarity a method for operational prediction of forest fire dynamics has been developed. It consists in building and training of the convolutional neural network (CNN). The paper describes the general logical scheme of the proposed method. CNN construction and setting is performed on the basis of the following data: the real-time fire data from the satellites using MODIS and VIIRS, data on environmental factors, data on the type of forest plantations and the type of fire. CONCLUSIONS. The developed operational prediction method based on Artificial Intelligence and Deep Machine Learning allows to analyze visual data and reveal the key dependences of forest fire propagation on the environmental factors, the type of forest plantations and the type of fire.

When studying the development prospects of coal-mining regions, the use of a computational experiment is rather labor-intensive, moreover, it is difficult to formalize. This is due to the features of coal industry as an object of research. The article presents the simulation models constructed at Melentiev Energy Systems Institute SB RAS in order to study the development prospects of Russian coal industry as a whole and the eastern regions of Russia in particular. The models are implemented in the framework of the information and model complex (IMPC) Coal. PURPOSE. The purpose of the paper is to consider the possibility of implementing the simulation models in order to study the development prospects of the coal industry. MATERIAL AND METHODS. The study uses the methods of system analysis, evaluation of investment projects, decision-making under conditions of uncertainty. Official statistical data and forecasts of regional economy development are used for model verification. RESULTS. The paper presents the simulation models being implemented including the models designed to evaluate investment projects of enterprises and groups of enterprises and 3 types of balance models. The models can be used independently or together with optimization production and transport models. CONCLUSION. The complex structure of the research object, the complexity of formalizing the dependencies of coal industry development indices on individual, most significant factors, the prevailing role of an expert in research do not allow to use the computer models with the fixed input and output. Simulation modeling is an effective tool for studying coal industry development prospects in the regions of Russia. The repeated computer experiment on the basis of the presented models has proved the rationality and feasibility of their use.

The study deals with the improvement of control methods of the air and gas path of a boiler unit. The PURPOSE of the work is to develop the models that allow for object dynamics. Dynamic models enable more accurate prediction and control of the process as compared with classical automatic control systems. METHODS. The article discusses the application of the well-known methods of Box D.J. and Jenkins G. for steam production process identification. RESULTS AND THEIR DISCUSSION. The object of the study is a boiler unit, which is a very complex and interconnected system. It is described as a dynamic stochastic object with uncontrolled disturbing influences. Using experimental and statistical methods, a mathematical model has been obtained. It allows to determine the influence degree of the raw coal feeder rotation (fuel consumption) on the flue gas pressure in the stack of the boiler unit air and gas path. CONCLUSIONS. The conducted studies resulted in obtaining the models that allow to evaluate the effects of raw coal feeder rotations on the flue gas pressure in the stack at the points of 122 m and 24 m. The developed model can be used for prediction and control the pressure of flue gases in the stack of the air and gas path of the boiler unit.

PURPOSE. The paper introduces a new variant of the improved design of a pipelayer boom additional support. The proposed technical solution increases pipelaying smoothness and improves pipelayer stability when in operation. The result is achieved by adding extra elements into the construction of the pipelayer boom support. The purpose of the work is to check the strength and performance of the proposed pipelayer equipment. METHODS. The existing method of strength calculation of the proposed design is rather laborious. The software product Solid Works is used to determine the critical stresses, strain values and maximum shifts in the design. RESULTS AND THEIR DISCUSSION. The cargo boom in the proposed construction is joined with the support, which consists of a hydraulic cylinder and a metal base used for cylinder fixation to the support with bolted-type connection. The dependences gained from the computation pattern of the pipelayer working equipment are given to prove the efficiency of the proposed design solution. The calculated dependences allow to determine the rate of the loads applied to the pipelayer. CONCLUSIONS. The results of the theoretical researches carried out in Solid works are represented by diagrams and show the stresses, shifts and deformations in the design of a pipelayer boom used for long-distance pipeline laying. Moreover, the size of the strength margin in the pipelayer boom support structure has been determined.

The PURPOSE of the article is to carry out an experimental study of the effect of the tire tread pattern wear on the implemented coefficient of adhesion to the support surfaces of the test bench under the variation of normal load value. METHODS. The studies were performed on the test bench of modular design, which allows to measure the normal and tangential reactions of the elastic tire with support surfaces. RESULTS. It has been determined that the increase of the tire tread pattern wear from 10 to 90% reduces the adhesion coefficient of the automobile wheel elastic tire by 35.3% when braking in the locked mode on a flat support surface. When the wheel brakes on one support roller of the test bench and the tread wear is from 10% to 90% the adhesion coefficient reduces by 18%. When the wheel brakes on two support rollers of the test bench the coefficient of adhesion makes 23.8% on the front roller and 48.4% on the rear support roller of the stand, with an increase in the wear of the tread pattern from 10% to 70%. CONCLUSION. The conducted experimental studies allowed to determine the dependence of the adhesion coefficient of the elastic tire on the wear degree of the tire tread pattern and the variation of normal load under the locked wheel braking on the flat support surface and one or two support rollers.