The purpose of the work is to determine the volume of material destroyed by a single grain (microasperity), which produces elastic and plastic deformation of the material when an abrasive tool interacts with the treated surface. To calculate the intensity of deformation of the plastically displaced material of the workpiece under the action of a single grain, the slip-line technique (method of characteristics) was used. To determine the volume of material destroyed by a single grain as a result of polydeformation when moving in the tangential direction, the following is determined: area of the deformed material; intensity of the shear deformation; speed of the shear deformation rate; number of plastic deformation cycles necessary for the destruction of the material in various zones of the sliding line field. The solution to these problems is found using the radii of curvature of the sliding lines in the physical planes and in the planes of the velocity hodographs for the meridional and normal to the axis planes of the grain section. The determination of the elastic deformation of the material is taken into account when calculating the roughness of the treated surface. Chip formation under the action of a single grain is considered taking into account the determination of the cross-sectional area of chips. This formed the basis for a determination of material removal during abrasive processing. The theoretical provisions for the determination of the above indicators are confirmed by experimental data. Thus, the studies carried out by the slip-line method formed a basis for determining the volume of plastically deformed material, the magnitude and rate of deformation under the action of a single grain, as well as the volume of the removed material as a result of repeated plastic deformation and in the form of chips. The performed investigation forms an integral part of studies into the process performance and roughness of the machined surface when finishing workpieces with elastic polymer-abrasive tools and free abrasive particles.

We set out to determine formal conditions for selecting rough datum surfaces and rules for specifying the relationships between the surfaces of the workpiece and the part machined by metal-cutting equipment. The research was based on the geometry of non-ideal objects, which represents the geometric configuration of the part or workpiece in the form of a set of surfaces (S) arranged in strict accordance with a set of linear and angular dimensional relationships (V) in a sixdimensional geometric space. The representation of dimensional relationships in each of the six dimensions was performed using graph theory. The algorithm described in the works of V.G. Starostin and V.E. Lelyukhin was used for modeling the process of sequential surface machining. The question of selection of rough datum surfaces was considered. Here, the selection criterion is the possibility of automatic formation of machining sequence without recalculation of the dimension chains defined in the drawing. This criterion eliminates the problem of significant toughening of tolerances and additional 

The underground working environment of the shearer is complex and the working conditions are relatively poor. It is necessary to continuously adjust the height of the rocker arm during the operation, improve the operation efficiency, and improve the ability of the shearer to adapt to the more complex coal seam working environment. In order to optimize the structure of the shearer adjustment mechanism, the strength and strength of the adjustment mechanism are improved by increasing the size and angle of the adjustment mechanism and reducing the size and angle. Therefore, an optimized particle group design method is proposed to optimize the drum adjustment mechanism of the shearer. Seven parameters such as large lever, small lever and maximum swing angle are selected as design variables. Under the condition of limiting mining height and rocker length, an optimization model with rolling angle and cylinder stress as objective functions is established. The working characteristics of each part of the coal machine height adjustment mechanism are analyzed. The particle swarm optimization algorithm is used to optimize the key parameters, and the optimization results are verified to ensure their accuracy. The optimization results are compared with the original parameters. The results show that compared with the pre-optimization, the cylinder stroke is shortened by 17.9%, the cylinder length is shortened by 8.94%, the rolling angle is reduced by 2.83%, the cylinder tension is reduced by 12.1%, and the rocker bending moment is increased by 6.83 %, which meets the original design goal. Therefore, the research provides a reference for the optimal design of the coal machine height adjustment system.

The article aims to study the distribution of residual stresses across the surface layer depth following the machining of test specimens (free orthogonal cutting and burnishing). The machining by cutting and burnishing of 45 steel specimens was carried out using a milling machine with numerical control under varying machining factors. For a comparative analysis, the processes were also modeled via the finite element method using identical experimental values of geometric parameters and machining modes. In order to obtain residual stress distributions across the surface layer depth, probe holes having depths of 0.5; 0.75; 1; 1.5; and 2 mm were drilled. By differentiating the displacement of specimen surface particles, measured using digital image correlation, radial strains around the probe holes were determined. Then, these values were used to determine the residual stress components for each probe hole, and the averaged values of each residual stress component were calculated using the calculation algorithm presented in this article. After burnishing the specimen with a force of 3400 N, the test value of the σx component within the depth range (from the surface) of 0.5–0.75 mm amounted to -250 MPa. Model and experimental distributions of residual stress tensor components across the surface layer depth were obtained following machining via two methods. The experimental values of residual stresses were found to have good convergence with each other and with model distributions at depths up to 1 mm from the machined surface at a drill diameter of 1.7 mm. The proposed approach provides a means to obtain the residual stress distribution across the surface layer depth by drilling probe holes of different depths and estimating radial strains on the specimen surface using the digital image correlation method.

The present work is aimed at enhancing the grinding efficiency of abrasive tools by designing and selecting their optimal characteristics. To that end, regularities in the process of defect-free grinding of workpieces made of hard-tomachine corrosion-resistant stainless steel of 12Х18Н10Т grade, nickel alloy of ХН60ВТ grade, structural steel of 30ХГСА grade, and complex-alloyed steel of 12Х2НВФА grade are studied by simulation modeling in the DEFORM software environment. The temperature in the cutting zone is selected as a criterion determining the quality indicators of the grinding process. The research methodology is based on the theory of metal cutting. It was established that each of the investigated abrasive tools, i.e., 1 25A F60 O6V, 1 25A F60 Q6V, 1 25A F80 O6V, and 1 25A F80 N7V is characterized by its rational field of application. For the “Pin” workpiece, the economic effect achieved due to elimination of scrap caused by grinding burns on the ground surface amounted to 18,095 RUB. In terms of the Ra parameter, an improved roughness of the machined surface can be achieved by small cutting depths (from 0.05 mm to 0.25 mm) in combination with a driving wheel speed of up to 108 min-1. The required accuracy of machining can be achieved by cutting depths of up to 0.25 mm in combination with a driving wheel speed of 86 min-1. Hence, a new methodology for designing and selection of abrasive tools is proposed. This methodology ensures minimal softening of the ground material, as well as the required surface roughness, accuracy of workpiece dimensions, and machining performance. In future research, coarser-grained (F40, F36) abrasive tools should be investigated.

The article is aimed at simulating an electric field in the interelectrode gap during the electrochemical machining of a thin-walled part cavity for aerospace equipment. The study involved simulating the process of electrochemical cavity machining at a constant voltage in a steady-state mode in the COMSOL Multiphysics environment. The simulation was carried out for the scheme of electrochemical machining with a movable cathode and vertical and horizontal feeding to the workpiece surface undergoing machining while maintaining a constant interelectrode gap. The following simulation conditions were adopted: 12Cr18Ni10Ti stainless steel as the material of the cathode tube; AlMg6 aluminum alloy as the material of the thin-walled part; NaNO3 solution as the electrolyte. When simulating the electric field in the interelectrode gap, the heat exchange process was taken into account. The simulation of the electric field in the electrochemical cavity machining of a thin-walled part yielded a macro that allows the process simulation to be adapted to different input process conditions. As a result of the simulation, the following distribution patterns were obtained: current density in the cathode, potentials, electric field in the interelectrode gap and adjacent area, and process temperature of electrochemical machining. The simulation results show that the electric field lines are directed toward the cathode from the workpiece periphery. This means that anodic dissolution of material occurs in a given region, which characterizes the law concerning the distribution of potentials in an electrochemical cell. The temperature distribution pattern obtained in the simulation revealed that a temperature increase in the machining zone is insignificant. An increase in electrolyte temperature is shown to result in a proportional increase in wall temperature. Thus, the conducted study provides a theoretical insight into the examined process.

The purpose of the study is to solve the problem of design of daily load profiles for optimal control of an environmentally friendly commercial and industrial microgrid (CIM) (power is generated only by renewable energy sources) connected to the power system by a power transmission line. This goal is achieved by adjusting the planned daily load profiles of consumers located on the territory of the CIM. The adjustment means shifting power consumption to another time of the day in question (power consumption is delayed). The problem of the delayed power allocation is represented as an optimization multiple knapsack problem that adapts to the problem-solving process. The proposed algorithm was tested on a 6-node system according to the scenario that involved adjustment of the load profile in the CIM to ensure that the power flow from the power system remains within specified limits. Compliance with the limits guarantees uninterrupted power supply from the power system, which is a fundamental requirement when developing load profiles. Experiments were carried out to evaluate the delivery of uninterrupted power supply to CIM consumers depending on the initial data. The findings indicate that the disruptions in power supply to CIM consumers are completely eliminated if the load can be divided to shift it to other hours of the day and when the load of 0.151 MW is disconnected in operating state 7. The total load should be divided into at least three parts. Disconnection of 0.151 MW is performed to prevent disconnection of the commercial and industrial microgrid from the power system, which would result in a power deficit of 4.652 MW.

The article is aimed at extending the speed range of a permanent-magnet synchronous motor in the main-motion electric drive of a machine tool (while maintaining the power characteristics). In this work, the electric drive of a permanent-magnet synchronous motor was mathematically modeled using the SimInTech software. As input data for modeling, the following DC motor parameters were used: nominal power of 2.2 kW, voltage of 315 V, speed of 1500 rpm, energy conversion efficiency of 90.5%, and nominal current of 6 A. An algorithm for controlling the electric drive was developed to include two control zones: zone of maximum power and increased speed zone. It is shown that in the maximum power zone, the nominal characteristics are maintained, while in the increased speed zone, an increase in motor speed of up to two times is achieved in the main-motion electric drive of the machine tool without a decrease in its power characteristics. Numerical experiments were conducted, as well as an analysis comparing the control algorithm and conventional control methods, which confirmed the theoretical values. The modeling results showed that with the control of permanent-magnet synchronous motors, the power consumption of a control system in the second zone does not exceed the nominal values. Thus, the developed system for controlling permanent-magnet synchronous motors provides effective control over the main-motion electric drive of a machining tool that demonstrates improved performance in machining materials made of low-hardness metals. The present study is of practical importance for industries in which increasing motor speed in machine tools constitutes an important factor in improving capacity and reducing machining time.

The article aims to review the literature on methods for implementing virtual inertia of wind and solar power plants, which can be used to improve control over them. About 50 scientific articles and reviews selected from  various scientific sources (including IEEE, Web of Science, and Scopus) using the following keywords were examined: wind turbine, wind farm, virtual inertia, microgrid, energy storage systems, supercapacitor, and frequency control. The method of systematic review of specialized sources was applied to provide a well-defined structure for a given field of study through article categorization. Works devoted to reducing the negative impact of renewable energy sources on the energy system were analyzed. The article shows the relevance of developing technologies that enable an improvement in the control capabilities of a power plant using renewable energy sources since their low inertia leads to a decrease in the stability of energy systems. The literature analysis indicates that one of the solutions to increase the stability of such energy systems involves creating virtual inertia in wind turbines and solar panels. However, due to the limited capacity of individual generating units, the effectiveness of implementing virtual inertia may not be sufficient when it is implemented independently in individual units. In this connection, it can be promising to create virtual inertia using a hybrid system comprising a supercapacitor and a generating unit controlled via the virtual synchronous generator method. This review analyzes specialized sources on the methods for implementing virtual inertia in energy systems with wind and solar power plants. It is concluded that no studies of the proposed approach have been conducted or presented to date, and the ideas described in the overview can be confirmed by developing the required algorithms and analyzing the results.

This paper aims to establish a comprehensive photovoltaic power generation prediction model. By collecting photovoltaic power generation data and weather data for a year, we analyzed the photovoltaic output characteristics in different seasons and found that the output characteristics in different seasons are also different. This article uses three neural network models, Long Short Term Memory Network, Recurrent Neural Network, and Dense Neural Network, to analyze the output characteristics of different seasons. Training, prediction, and prediction error analysis found that different models have different prediction accuracy in different seasons. Therefore, this paper proposes a weighted ensemble model add weights model based on the Nelder-Mead method to train and predict different seasons respectively. By analyzing the prediction error, the prediction accuracy needs to be better than a single model. We add noise to the data set to simulate unstable lighting conditions such as rainy days, and train and predict the data set after adding noise. The prediction results show that the comprehensive model has higher prediction accuracy than a single model in extreme weather. In order to verify the reliability of the model, this article uses a sliding window to extract the confidence interval of the prediction results, and uses the Bootstrap method to calculate the confidence interval. By analyzing and comparing each model’s Average Coverage, Root Mean Squared Length, and Mean Width, the prediction accuracy and reliability of add weights model are better than those of a single model.

The article is aimed at increasing the effectiveness of numerical optimization methods in calculations of problems concerning power shortage minimization in electric power systems, specifically the differential evolution (DE) method and its variations–aDE and jDE. Experimental studies and testing of the proposed adjustments were carried out on complex electric power systems of different order. These systems are represented and realized by means of mathematical models of power shortage minimization with the possibility of their analysis using the developed software package as part of adequacy assessment. The performed analysis of the DE method elements and the existing variants of the mutation process revealed that the existing approaches can be further modified. This can subsequently increase the speed of problem-solving. It is shown that the main changes include an additional check that the mutant vectors meet the upper and lower bounds, and if they fail to do so, three adjustment options are considered. Existing approaches propose to generate new vector elements beyond the bounds by applying random numbers within the bounds. The present authors propose to use the “projections” of the found vector elements, i.e., to use the values of upper or lower bounds when they are exceeded for a particular element as mutant vector values. The implemented method involving the adjustment of mutant vector elements is shown to offer an advantage of a 47% reduction in problem-solving time over existing adjustment methods while maintaining the same accuracy. It is noted that aDE and jDE are the most effective variations for solving stated problems. The obtained results of experimental studies confirm the effectiveness and advantages of applying the proposed adjustment method in mutation process of in the form of “projections”, as well as using aDE and jDE variations of the DE method to solve the problems of power shortage minimization in electric power systems.

We propose a technology for processing of copper-zinc ore flotation tailings with the purpose of extracting gold using ultra-low (10–30 mg/dm3 ) concentrations of NaCN. The material composition of the starting materials was examined using the methods of inductively coupled plasma, gold assay atomic absorption and X-ray diffraction analysis. The NaCN concentration in solution was determined by titrimetric and photometric methods; pH levels were determined by potentiometric analysis. The laboratory studies established optimal conditions for cyanidation of tailings resulting from flotation beneficiation of copper-zinc ores, which underwent preliminary lime treatment: mass fraction of the 0.071-mm mesh minus – 70.5%; duration – 8 h; NaCN consumption – 0.3 kg/t (at a concentration of 30 mg/dm3 ); L:S =1:1. Under these conditions, the gold extraction rate amounted to 32.0–33.6%. Pre-grinding of flotation tailings to the size of 90% of the 30 mm mesh minus led to an increase in gold extraction of up to 41.5–44.7% at an NaCN consumption of 0.6 kg/t of the same concentration and L:S =1.5:1. The results obtained served as the basis for experimental cyanidation of waste tailings according to two schemes, i.e., using tailings of initial coarseness and pre-ground tailings. A good agreement was achieved between the laboratory and experimental results. At present, the use of pre-ground tailings seems unreasonable economically, due to high costs of NaCN (0.6 kg/t vs 0.3 kg/t) and active chlorine (5.6 kg/t vs 1.2 kg/t). According to pilot tests on a flotation tailing sample weighing 67 t (with an Au content of 1.35 g/t), the gold extraction level was 31.9% at an NaCN consumption rate of 0.135 kg/t. As a result, we propose a technology of gold extraction from flotation tailings of copper-zinc ore based on the application of ultra-low concentrations of NaCN. The expected profit can amount to 1276.74 mln RUB per year, with the economic efficiency of 88% and the payback period of 1.4 years).

The article aims to select a filter design and mode of washing cake in the hydrometallurgical processing of polymetallic sludge in order to minimize the volume of washing water and obtain a high-quality cake—iron oxide pigment precursor. An analysis of the chemical composition of the subject matter–pulp following hydrochloric acid treatment of polymetallic sludge—was performed using atomic absorption spectrophotometry and X-ray fluorescence spectrometry, while the particle size distribution was studied via laser diffraction. The analysis of the chemical composition revealed that the liquid phase contains, g/dm3 : MgCl2 90.5–105.6; AlCl3 35.8–37.6; NiCl2 8.1–9.0; FeCl3 24.5–27.1; CrCl3 5.9–6.5; MnCl2 2.1–2.4; HCl 6.5–7.7. The solid particles present in the pulp are represented by two distinct groups of particles having the following sizes: 0.1–1 µm and 1–120 µm. It was found that pulp separation using a chamber-membrane filterpress with the vertical arrangement of plates minimizes washing water volume up to S:L 1:1, returns the mother liquor captured by the cake to the process cycle, and helps to obtain high-quality washed cake with a minimum content of residual salts (0.5 wt%). The optimal temperature of the pulp entering the filtering process is 80℃, while that of washing water is 60℃. Cake washing was shown to be the limiting step of the pulp separation process, which can be realized via the displacement method given the use of acidified water with pH 1.5. It was found necessary to use filter cloths made of 100% polypropylene, with a specific weight of the fabric of 540 g/m2 ± 10%, air permeability of 6 L/dm2 per minute ± 30% at 200 Pa, and a maximum operating temperature of at least 90ºC. Thus, the specific capacity of the filter press was calculated and a standard machine with the vertical arrangement of plates and a filtering surface of 500 m2 was selected for pulp separation following hydrometallurgical processing of wet polymetallic sludge (8000 tons/year).

The article aims to determine the magnetohydrodynamic parameters of an aluminum electrolyzer in order to compare different types of bus arrangements used in baths with a Soderberg anode. The electrical parameters of the electrolyzer (current distribution across blooms and anode studs) and magnetic field parameters were computed using the Blums V5.07 program (Polyfem, Russia). Data on circulation rates and skew of the metal in the electrolyzer were obtained using the MHD-Valdis program (developed by V. Boyarevich, University of Greenwich, UK). In the course of the studies, mathematical models of the C-8BM (C-8B) electrolyzer with various bus arrangements were built. Three bus arrangements were selected for testing the installation of a bridge designed to close the current distribution in the anode bus arrangement of the electrolyzer. These types of bus arrangements were realized in two variants: with and without a bridge. The obtained circulation rates and skew of the metal were used to evaluate the possibility of modernizing baths with a Soderberg anode without significant capital costs. When using the first type of bus arrangement, the best current distribution was achieved for the blooms with limits of ~757 A (for the variant without a bridge) and ~656 A (for the modernized variant with closed series), as well as for the anode studs having limits of ~1754 A and ~1609 A, respectively. With the use of the third bus arrangement variant, the current distribution was shown to slightly decrease following the installation of a bridge between the anode bus bars. The obtained results suggest that in the modernization of a C-8BM (C-8B) electrolyzer with different types of bus arrangements, current distribution across blooms and anode studs, magnetic field characteristics (By and Bz components), as well as circulation rates and skew of the metal, have no significant impact on the efficiency of this electrolyzer, which contributes to a faster transition to EcoSoderberg bath electrolysis without significant economic costs.

The aim of the work was to study the leaching kinetics of zinc from the compound CaO. ZnO, formed during the sintering of dust from electric arc furnaces with limestone, as well as to identify the mechanisms by means which such chemical interactions occur. The object of the study was the dust sinter of electric arc furnaces with limestone obtained at the Chelyabinsk Zinc Plant. It was found that zinc is contained in sinter in the form of readily soluble CaO. ZnO. The elemental composition of the initial dusts and sinter was determined by the spectral atomic emission method using inductively coupled plasma on a Spectroblue optical emission device and spark spectrometry. The phase composition of the materials was studied on a Bruker D8 Advance X-ray diffractometer. The initial sinter was milled to apowder state having a particle size of ~0.04 mm and with a yield of ~97% of the composition, %: 11.9 Zn; 28.5 Ca; 16.6 Fe; 0.38 Mg; 0.14 Pb; 0.05 Cl. Experiments on the leaching of Zn with NaOH solution were carried out at the following parameters: the initial concentration of zinc in the pulp was 0.202 g-ion/dm3 ; alkali concentration – 5‒9 mol/dm3 NaOH; L:S = 9:1; pulp mixing rate – 10‒20 rad. c-1; temperature – 333‒363 K; duration – 0.5–2.5 hours. It has been shown that zinc from sinter passes into solution as sodium tetrahydroxozincate Na2[Zn(OH)4], while calcium remains in the cake, mainly as insoluble Ca(OH)2, which reacts with carbon dioxide to form insoluble calcium carbonate CaCO3. The process of dissolving zinc from the sinter corresponds to the external diffusion mode of mutual transfer of the initial reagents and reaction products through the surface layer of the liquid at the interface of the “liquid–solid” phases with an activation energy value equal to 12.44 kJ/mol. Thus, with the studied parameters of zinc leaching with NaOH solution, the process proceeds in an external diffusion mode. The results are of interest when identifying conditions corresponding to the intradiffusion and kinetic modes of zinc leaching.