Introduction. The phenomenon of the droplet impingement erosion which develops in the metallic materials at the frequencies of drop collisions of 50 ... 200 s-1 and velocities of 150 ... 600 m/s is considered. The comparative estimability of the wear resistance of materials of various structural classes and with different levels of mechanical properties is investigated. The major goal of the work is the development of a computational and analytical model of erosion wear of hardened materials. In parallel, the problem of the criterial evaluation of materials, with the help of which they could be attributed to plastic or reinforced materials and then used as a corresponding model of the fatigue failure mechanics, is solved.

Materials and Methods. The well-known dependences of the fracture mechanics and the fatigue theory of Paris-Erdogan are used for the computational and analytical estimates of the erosion resistance of materials. The calculated expressions parameters are obtained on the basis of the bench erosion test results and scanning electron microscopy data of samples of 20Cr13 steel with a martensitic structure.

Research Results. It is suggested to use limiting state diagrams of the ductile and durable materials as their classification criterion. In particular, the initial and critical size of the brittle fracture can be determined on the basis of such a diagram of the hardened materials. These values are used in the basic model to calculate the erosion resistance of the material. Based on theParis equation from the fatigue theory of ParisErdogan, a computational and analytical model for estimating the erosion resistance of the hardened materials is developed and scientifically proven. Their surface degradation occurs according to the mechanism of nucleation and development of cracks of the clasped type. The calculation data are presented for samples of martensitic 20Cr13 steel using the experimentally obtained parameters of theParis equation.

Discussion and Conclusions. The results obtained are relevant for the selection, optimization or development of the erosionresistant materials for high-speed blades of the steam-gas turbine and compressor equipment operating under the conditions of condensate formation.

Introduction. The study results of the passenger ropeways (PRW) applicability in the highly urbanized environment are presented. Issues on the development of mathematical models for designing and simulating work processes of the advanced “Rope Metro” transport system are considered. The proposed transport system differs significantly from the customary PRW. For its successful design, a mathematical model for estimating the operational loading of the key components is developed. Likewise, a mathematical submodel of the passenger cabin of the cable car which will be then integrated into the composite mathematical model of the system is offered by the authors. The work objective is to study the passenger cabin oscillations during its movement along the section of the transport system.

Materials and Methods. A new mathematical model describing the oscillations of the passenger cabin and its suspension members is proposed. This model should be integrated into the composite mathematical model of the transport system using part of its output capacity. Numerical simulation of the cabin movement is carried out. The derived equations represent a mathematical model for studying the dynamics of the pendular oscillations of the passenger cabin of the advanced “Rope Metro” transport system. In the paper, the integration of the equations is carried out by the Runge-Kutta method in the program package of the in-home design.

Research Results. New mathematical models and software for the numerical simulation are developed. The damping devices’ effect on the maximum oscillation amplitude of the passenger cabin is shown.

Discussion and Conclusions. The results obtained can be used under designing and modeling work processes, and optimizing the transport system components. It is proved that the damping device reduces the amplitude of the oscillations which stabilize at lower values (0.3-0.5 degrees) after the transient process end. In the future, it is required to integrate the developed mathematical model into a composite model of the system under investigation to refine the conclusions reached.

Introduction. The radial profile turning features are compared with the conventional turning by a straight tool with a fixed shear area. It is assumed to determine power characteristics in the cutting area by means of the calculated force dependences that take into account instantaneous shear areas and mean specific pressures available from experiments. Thus, the problem is solved in two stages. First, shear areas for various shaped profiles are determined, and then, experiments are performed to obtain mean specific pressures on the cut sites. This work objective is to solve problems of the first investigation stage: determining the instantaneous shear areas for different profiles of the shaped radial turning taking into account their dependence on the geometrics and time parameters of the radial penetration.

Materials and Methods. Analytical dependencies are developed to solve the tasks. They make it possible to determine the instantaneous shear areas under radial turning of convex, concave and combined radius profiles in the course of cutting in. At this, cutting time, length of penetration, approach angle, and feed are taken into account. Shear areas and their increments can be determined through each full turn of the part. The analytical dependences obtained suggest features and variations in the magnitude of the instantaneous shear areas under radial shaping.

Research Results. Instantaneous shear areas under the radial rotation of convex and concave radius profiles taking into account the geometrics and the increment time are calculated from the dependences obtained. This implies optimal conditions and modes of shape cutting.

Discussion and Conclusions. Analytical dependencies and tabulated values of the shear areas are the background for determining power characteristics and energy costs on the basis of the specific pressures for shaped radial turning.

Introduction. The use of the magnetic-pulse treatment method which helps to eliminate and prevent annular seam defects is considered.

Research Results. The method is developed for using magnetic-pulse alignment to eliminate deformations that are formed under welding and due to residual stresses. The welded seam is deformed and takes the position that fails to meet the product requirements. The result is local bending, which is 0.5−2.0 mm, and the diameter reduction in the annular seam area.

Materials and Methods. Theoretical analysis is performed, and a practical research technique is tested. A twisted inductor for expansion and copper satellites for transmitting magnetic pressure are used for the experiments.

Discussion and Conclusions. The workability of the magneticpulse treatment to eliminate and prevent deformations in the annular seams is determined. That makes it possible to align the annular seam remotely, or prestrain structural components ensuring for virtual deformation compensation before the welding. It is expedient to process pipes and rings of 100 mm in diameter with 2-5 mm WT by the current induction, and by the expansion technique.

Introduction. The die stamping (DS) process of the compound cross-section in an open die is considered. The work objective is to determine the form and number of operating steps to obtain the limiting conditions by the adopted parameters. During the investigation, the following lower parameters are determined: uneven strained condition of the considered section of the finished forging; metal consumption on the forging flashes; relative length of the stage of stamping finishing (metal flow only to the flash).

Materials and Methods. The study is based on the use of the numerical finite element method (FEM) for the solution to direct and inverse problems of the component forming under die forging. QForm package is used as a software tool.

Research Results. It is shown that the metal consumption can be reduced from 13-17% of the forging volume in the selected section to the values of 1.8 to 3.5%. The relative length of the stamping finishing stage can be reduced from 17% to 0.4%. The nonuniformity of the distribution of the cumulative deformation along the cross-section is estimated by the corresponding criterion. It can be reduced to the limits typical for optimization-level tasks (when using a profile piece-part) or a level of rational values (under the introduction of a single blanking pass).

Discussion and Conclusions. The quantification of stamping processes considered in this paper can be applied in the generalized type to any form of DS products. This allows improving the quality of forgings and significantly reducing their production cost.

Introduction. The technology of single-pass arc welding under a thin layer of slag (AST) of thick plate welded structures in the thermal and nuclear engineering is considered. The structure material is 09G2S steel. The work objective is the experimental study on the applicability of the AST method instead of the automatic welding under flux (AWF) and electroslag welding (ESW) under manufacturing the package units of the power plants.

Materials and Methods. The technology is developed on the basis of the calculation results of the thermal welding mode (thermal cycle parameters and welding mode settings). Test joint weld-samples, 100 mm thick, are made of 09G2S lowcarbon low-alloy steel. Welding is performed on the certified equipment of “EMC-Atommash” JSC. The welded joints quality is assessed on the standard control results by the following techniques: magnetic-particle testing (MPT), ultrasonic control (USC) and radiographic testing (RT). The non-destructive testing results were supplemented with the metallographic study data. To investigate the nature of the weld metal crystallization along the length of the weld, the macrotemplates were cut out mechanically from the middle through-the-thickness and at the distance of 10 mm from the surface. The technique and installation of “TCS-1” for simulating the thermal cycle of the metal welding of the heat affected zone (HAZ) of the welded joints; standard methods for determining mechanical properties; hardness and microhardness indices; and method for determining the grain size in micrographs according to GOST 5639-82 were used in the experiments. The microstructure was studied with MMP-2P and Reichert optical microscopes with increase up to thousandfolds. Besides, the distribution pattern and identification of the second phases of nonmetallics; welded samples and samples modeling the HAZ metal for the notch sensitivity; structure stability and welding cracking resistance were studied through the replica technique using the EMV-100LM electron microscope.

Research Results. Based on the thermal calculation results and the HAZ metal modeling, the optimum values of the heat input and welding variables are validated and experimentally verified. The welded joints quality is estimated by the nondestructive and destructive methods. The effect of the welding method on the structure, quality and mechanical properties of the welded joints is established.

Discussion and Conclusions. Positive results of the theoretical and experimental studies are obtained. They indicate the technological and economic efficiency of the AST method application (instead of AWF and ESW) under manufacturing the 100 mm thick welded joints of 09G2S low-alloy steel. Moderate heat input in AST allows for the one-pass forming of a welded joint with better fine-grained structure and higher mechanical characteristics as compared to the ESW and AWF. Recommendations on the use of the AST technique in the welding production are given.

Introduction. At present, developers and researchers focus on the automated maintenance of the machine performance, especially under the conditions of the production computerization. The opportunities for assessing technical state of the equipment, fault diagnostics and monitoring are greatly expanded. This allows preventing failures and minimizing the impact of disadvantages on the performance. For this purpose, some autonomous control system is developed. Its conceptual problems are discussed in this paper.

Materials and Methods. The autonomous control system of the machine technical state is considered. It is shown that signals from the sensors and to the actuating mechanisms arrive through the distributed control nodes of the technical state of the machine devices. Therewith, proper communication is provided by e-MindMachine. Generalized functions for managing the technical state of metal cutting machines include the decision making and command execution involving built-in facilities. The specificities in the construction of the machine maintenance system are described and explained. As a result, the following statement is established: when analyzing processes in the machine tools and in the solution synthesis for controlling the machine maintenance (MM), methods of artificial intelligence and intellectual control (including the theory of fuzzy sets and fuzzy logic) are adequate.

Research Results. This approach accumulates the achievements presented in the known maintenance systems of various machines, and it raises the service factor up to the independently operating systems of the automated autonomous control of the machine technical state. The system structure, the generalized control functions of which include the decision making and command execution using the built-in means, is considered. It is shown how methods of the theory of fuzzy sets and fuzzy logic are used in the solution synthesis for control. The incremental development and implementation of the autonomous system depending on the condition and capability of an enterprise are recommended.

Discussion and Conclusions. The issues on introducing the autonomous MM control system are considered. Appropriate methods for determining the sequencing of operations and evaluation of the performance are offered. The monitoring subsystem provides, firstly, the implementation of the traditional diagnostics under monitoring the machine state on-line. Secondly, it is supposed to perform the following functions: evaluation of the diagnostic results, and forecasting and decision making – in order to control the actions preventing damage to the device (or the machine as a whole).

Introduction. Homogeneous pyrolysis of propane is studied in a flow reactor with constant external heating. A numerical analysis of the results of simulating the gas flow in the reactor with account of chemical processes is required for a comprehensive study of the process under all kinds of conditions and for the control of the transition from laboratory facilities to the industrial ones. The results of the numerical modeling of the three-dimensional gas flow dynamics of propane pyrolysis in the reactor based on the ANSYS Fluent using a compact kinetic model are presented.

Materials and Methods. An acceptable size kinetic scheme of the pyrolysis of propane is proposed by the authors. The scheme is obtained using the methods of local and global sensitivity analysis of the model. The mathematical model used in the ANSYS Fluent package is given. The model is the equation of continuity, conservation of momentum, and conservation of energy, supplemented by the continuity equations for each gas component.

Research Results. The numerical simulation of the threedimensional dynamics of the gas flow of propane pyrolysis using the ANSYS Fluent software package and a compact kinetic model is carried out for the first time. Calculations of the gas flow dynamics of propane pyrolysis are conducted in the laboratory reactor with account of the diffusion processes, chemical reactions and their thermal effects. The numerical calculations results correlate well with the experimental studies on the conversion of propane.

Discussion and Conclusions. The results of the research and simulation of the propane pyrolysis can form the basis for describing the process in the reactor volume under the influence of the laser radiation.

Introduction. Mathematical models are developed to predict M25 and M10 coke quality. The calculations are carried out specifically for each of the coke batteries of the coke-chemical production (CCP) of Magnitogorsk Iron & Steel Works (MMK). The simulation is based on the charge factors: sum of inert components OK, %; vitrinite reflectance R0, %. These models are required to control the product quality and the optimization aimed at cost saving. The study objective is to construct adequate mathematical models for predicting М25 and М10 coke quality indices under the conditions of MMK CCP. Thus, it is assumed that MMK will obtain its own models that are highly competitive in forecast precision with the analogues used by other coke-chemical enterprises ofRussia.

Materials and Methods. Neural networks are used as a universal approximation for constructing mathematical models. When selecting their architecture, the authors emanated from the minimum number of neurons and the network layers. In addition, the minimization of the predictive error on a new sample was taken into account which was not used in training and testing.

Research Results. The development is based on the petrographic charge factors: sum of inert components OK (according to GOST 12112); vitrinite reflectance R0, (GOST 12113). With the help of artificial neural networks, one-dimensional mathematical models are constructed to predict impact coke strength indices of М25 and abrasion capacity of М10 (GOST 5953). The developed models are presented in a graphical form. Their predictive force is estimated.

Discussion and Conclusions. In the models developed within the framework of this study, only petrographic charge factors are used. The aggregate data on technical and plastometric analysis are not taken into account. This is the basic difference of the approach presented in this paper from the models implemented for other CCP, for example, at Nizhny Tagil Iron & Steel Works (NTMK), Novokuznetsk Iron & Steel Works (NKMK), and West-Siberian Iron & Steel Works (ZSMK). Even so, the adequacy of the obtained dependences is proved. It is proposed to use them to optimize the petrographic charge factors by various optimality criteria of the coke quality indices.

Introduction. The analysis of the water quality functional sensitivity to the parameters of the multiparametric model of the artificial water ecosystem of the biological sewage treatment, which is formulated as an initial-boundary value problem for the system of reaction-convection-diffusion equations describing the biogen dynamics, is discussed. The use of the multidimensional non-stationary models of aquatic ecosystems with a detailed description of biochemical reactions is complicated by a large number of parameters, the importance of which must be obtained experimentally. To simplify the providing data process, the sensitivity of the water quality functional to the model parameters is evaluated.

Materials and Methods. A brief review of the existing estimation techniques is carried out. And further on, an algorithm for studying the functional sensitivity characterizing the water quality to the parameters of the water ecosystem model is formulated using methods of the theory of small perturbations and conjugate equations.

Research Results. The analysis algorithm of the functional sensitivity to the parameters of the aquatic ecosystem model is obtained. A practical example of the method application for the optimal control problem for an aeration tank (an element of the sewage treatment plant for the biological sewage treatment) is considered.

Discussion and Conclusions. On the basis of the analysis, the most and the least significant parameters of the mathematical model of the artificial aquatic ecosystem of the aeration tank, which is included as an integral part of the problem of optimal aeration control, are revealed. The sensitivity estimation algorithm given in the paper can be applied to other processes related to the mass transfer of reacting substances, such as the solution to inverse source problems of dynamics and kinetics of gaseous impurities and aerosols in the atmosphere, modeling of biological processes in living organisms, control of the mass transfer in devices of the chemical technologies, and others.

Introduction. The applicability of mathematical scaling and normalization in solving various applied problems is analyzed. The best known formulas often used along the theoretical and experimental studies are considered. The purpose of this work is to identify the properties of mathematical scaling and rationing.

Materials and Methods. The errors obtained under using the mathematical scaling and normalization formulas are considered via specific computational examples. Based on a comparative evaluation of the ratio of the degree of magnitude of the initial and resulting values (as well as the ratio of the degree of difference of these values), the correctness of the results obtained which significantly effects the final values is estimated.

Research Results. The analysis leads to the conclusion that some known mathematical scaling and normalization formulas possess properties that are ignored in theory and practice.

Discussion and Conclusions. The results obtained allow avoiding erroneous decisions caused by the use of invalid scaling and normalization formulas under solving problems in theory and practice of economics, administrative management, medicine, and plenty of other fields.

Introduction. Matters of selection and use of units for exhausted air heat utilization in the barn room are considered. The work objective is rationale for choosing the number of heat recovery devices that provide the greatest economic benefit when operating in the room for 400 animals.

Materials and Methods. Determination of the number of energy-saving equipment units is due to several factors. The key one is the ever varying amount of air exchange in the barn depending on the outer air parameters. At this, the operating conditions in the southern regions of the country are taken into account. Mathematical models describing dependence of the technical-and-economic indices on the number and operating period of the disposal plants are proposed. The correlationregression analysis of the dependences obtained is made. The technical-and-economic assessment of the use of heat exchangers is carried out on its basis. Contour plots of the objective functions of the electric power consumption and operating costs are presented depending on the operating period and the capacity of energy-saving plants. A comparison method is used to identify the most efficient performance of the heat exchanger with the varying value of air exchange.

Research Results. The desired number of heat exchangers, which provide the required air exchange in the livestock house, is determined. New mathematical models are developed for calculating the efficiency of utilization facilities taking into account the capacity and operating period. Dependences of the change in running costs on the performance efficiency of the utilizers are established. The number and type of the heat recovery units is determined. When these utilizers are in use, the greatest net present value is achieved.

Discussion and Conclusions. The results obtained can be used to develop energy-saving systems under stock-rearing. The proposed mathematical models for calculating operational costs allow for a pre-feasibility study on the use of plate heat exchanger in livestock buildings.

Introduction. The solution to the problem of reliability increase of the agricultural and reclamation equipment by improving the key reliability indices of the lead-acid accumulator starter batteries (ASB) under their operation and storage is considered. The work objective is to develop ways to improve the maintainability of the leadacid accumulators of the agricultural and reclamation machines under various operating and storage conditions.

Materials and Methods. Methods for increasing the performance characteristics of the lead-acid accumulators in the course of their operation and storage using organic compounds of the sterically hindered phenols (SHP as additives to the electrolyte at the rate of 1 g/l are proposed. The impact of the SHP on the conductor corrosion of smooth and porous lead-dioxide electrodes is assessed. For more objective evaluation of the inhibiting SHP properties, the life time tests of the commercial domestic batteries under plant conditions according to the current GOSTs and by cycling techniques are conducted.

Research Results. A technique for increasing the service life of a lead-acid accumulator using the SHP as an additive to the electrolyte is developed, since they have the properties to inhibit the corrosion process of the current collectors of the positive electrode.)

Discussion and Conclusions. The results obtained can be used in the operation of the ASB on the agricultural and reclamation machinery, motor vehicles, and other machines, as they slow down the corrosion process of the positive plate grids. In addition, SHP additives can be effectively applied in the seasonal mode of the lead-acid accumulator operation which is typical for operation in the system of the agro-industrial complex.

Introduction. Currently, the production and consumption of the electrical energy is constantly growing. One of the solutions to energy and environmental problems in Russia is harnessing of renewable resources, in particular, distributed-type solar-wind power plants. To reduce the generated electric power costs, it is worth to shift part of the energy to a combined solar-wind power station with the potential parallel operation with the central power supply system. Some options of supplying consumers with the electric power are considered. The volume of energy produced by solar-wind installations is determined. Besides, the most optimal objects with the power supply of which it is possible to use solar-wind plants of the batteryless distributed type are determined.

Materials and Methods. A technical and economic analysis of the application of solar-wind installations for various power supply facilities is carried out.

Research Results. The efficiency of using batteryless solarwind plants is shown under the parallel operation with the power network for agricultural production facilities.

Discussion and Conclusions. The results obtained can be used under designing and reconstruction of the power network systems of agricultural objects.

Introduction. Vertical upward flow of water in the plant xylem occurs under the action of the water surface tension in the capillary menisci. In some papers, it is shown that the distribution of water in the inclined capillary systems is subject to the general rule: movement of water reaches a maximum in the branches of a lower level. In this case, the water height in a vertical capillary is proportional to the number of lateral branches in the capillary system. A set of issues remains open, among them: the role of bordered pores providing a hydraulic connection between vessels; effect of pore sizes and parameters of hydraulically coupled vessels on the water rise in them. 

Materials and Methods. A model of the system consisting of two vertical capillaries of different radii is considered. They touch one another by side walls and are immersed in water. Calculations describing the relationships of the elements of the given system are carried out.

Research Results. It is established that the height of water in hydraulically coupled capillaries is generally different.

Discussion and Conclusions. The dependence is shown: the smaller the difference in level between pores and the closer the pore is to the water surface, the higher the water in the capillaries rises.

Introduction. Power transformers are the basic equipment of the industrial power systems. One of the key indicators of determining the service lifetime of the transformer including its performance characteristics is the condition and residual life of its isolation. Aging and f insulation deprecation are directly related to the operating temperature of the transformer in use, as well as to the reliable operation of the cooling system. This research direction is up-to-date, especially when it comes to fully rated power transformers.

Materials and Methods. Power transformers of the district substations that feed the industrial and transport enterprises are considered. Modes of power transformers, which are caused by the uneven workload of the phases and short-circuiting, are studied. All these factors lead to the thermal deformation of the power transformer insulation and, as a rule, to the outage of power transformers.

Research Results. The forced cooling system of power transformers, which allows increasing their cooling capacity and the cooling fluid volume, is developed by the authors and described in the paper. Thermal calculations of heating design elements of the power transformers are carried out both in the conventional cooling system and the new one. The comparative analysis and calculations have shown the feasibility of the developed cooling system of power transformers, which allows extending the insulation lifetime. The developed cooling system is forced. The authors used a reserve power transformer tank as an additional expander. This design solution can be implemented for transformers operating at low temperatures, as well as under long-term limit loads.

Discussion and Conclusions. The developed cooling system  eliminates the requirement for purchase costs on extra equipment and maintenance support. It can be used at the enterprise power facilities and in the rail transportation.