This study evaluates the effects of mandrel geometry on the force characteristics and surface quality of burnished tubular parts to determine appropriate parameters for the burnishing tool. The burnishing of Steel 45 tubular parts was simulated using the finite element method in ANSYS 19.1 R2. The effects of the lead angle, sizing land width, and back taper angle on the distributions of drawing force, residual stresses, and elastoplastic strains were investigated. At a lead angle of 2°, the drawing force reached its maximum due to friction, whereas angles greater than 4° impaired the quality of the machined surface. A reduction in the sizing land width to less than 2 mm resulted in unstable deformation, while widths greater than 3 mm increased friction and caused galling. In the absence of a back taper or at a small back taper angle of 2°, the drawing force increased sharply owing to the larger contact area and pressure concentration at the sharp edge of the burnishing tool. At a back taper angle of 8°, surface micro-irregularities began to develop, potentially impairing surface quality. Based on a comprehensive analysis of the burnishing process, the recommended mandrel geometry was established for an interference of 0.4 mm: a sizing land width of 2.5 mm, a lead angle of 4°, and a back taper angle of 4–6°. These parameters provide a minimum drawing force of 54.2–54.4 kN while maintaining high surface profile accuracy, with a deviation of approximately 3.5 μm.

The material parameters of a phenomenological hyperviscoelastic model were determined experimentally for I-73-361 rubber to improve the accuracy of calculations for highly elastic composite shells of machines and equipment under symmetric loading. Uniaxial cyclic tensile tests were performed on a Zwick/Roell/BT-FR010TE-A50 testing machine at a maximum strain of 20–25 %, corresponding to the elongation at break of the reinforcing cord. The elastic response of the rubber was described by the Treloar strain-energy potential, while its viscous response was represented by a model of an incompressible non-Newtonian fluid with strain-dependent viscosity. The experimental data were processed and the model parameters identified using the least-squares method, with the residual minimized by the Levenberg–Marquardt algorithm in Mathcad. The resulting material parameters for I-73-361 rubber were an elastic modulus of approximately 1.061 × 10⁶ Pa for branch A of the rheological model, an elastic modulus of approximately 7.610 × 10⁵ Pa for the elastic element of branch B, and two parameters defining the viscosity coefficient of branch B: a coefficient of approximately 1.901 × 10⁶ Pa·s and an exponent of approximately −0.284. The exponent characterizing the rheological behavior of the viscous component was approximately 0.828. The approximation error for the experimental stress–strain curves, including the hysteresis loops, did not exceed 5 % for the principal parameters. In contrast to the Bergström–Boyce micromechanical model, the proposed phenomenological model requires no additional uniqueness condition for the decomposition of the deformation gradient and can describe both an increase and a decrease in viscosity with strain. The identified parameters can be used to calculate the viscoelastic properties of highly elastic composite shells under symmetric loading. The dependence of viscosity on the first invariant of the Cauchy–Green strain tensor is not universal across elastomers. Whereas the Bergström–Boyce model predicts a monotonic increase in viscosity, the phenomenological model also permits a decrease, as confirmed experimentally for I-73-361 rubber.

This study aims to improve the stability and performance of control of the moving crosshead in the main hydraulic directional control valve of a 10,000-tf forging press manufactured by Ural Heavy Machinery Plant (UZTM, Russia). The press is used to produce rings of various profiles and materials as part of the ring-rolling process. Typical processes in the main system components were modeled using the TIA Portal software platform. Improved stability and control performance were achieved by developing and implementing specialized algorithms for processing signals from the manual joystick. The algorithms were tested on the actual equipment. A control signal generation algorithm was developed and implemented to limit the rate of signal change to a level sufficient to prevent hydraulic shock and to provide an S-shaped servo-valve flow characteristic through cascaded first-order lag elements, thereby minimizing transients. Testing confirmed that the processing block for joystick input completely eliminates the effect of the nonlinear region while maintaining a stable zero setpoint in the neutral position. The setpoint generation block ensures a smooth change in the servo-valve flow characteristic along an S-shaped trajectory without hydraulic shock. The modernization reduced equipment downtime for repairs by 7 %, confirming the practical effectiveness and economic feasibility of the proposed solutions. The developed algorithms and technical solutions were validated on actual equipment at an industrial facility in the Chelyabinsk Region. Implementation of the control system increased the operational reliability of the hydraulic directional control valve by 5–7 %, eliminated hydraulic shock, and provided accurate positioning with opening and closing times of up to 1.5 s. The proposed solution can be adapted to upgrade the control systems of similar hydraulic presses and other manually operated forging and stamping equipment, thereby extending their service life.

The present study aims to justify the possibility of using acoustic signals for correcting turning modes of computer numerical control (CNC) machines. The object of the study is the technological assurance of the required surface roughness during the machining of turned parts. Experimental planning and organization, spectral and correlation analysis, as well as optimization methods were used. Experiments were carried out using a CNC turning machine. St3 and steel 45 grades of structural steel were used for machining. The condition of the cutting insert was assessed using an electronic cutting tool measuring device. Vibrations were recorded using an accelerometer; the obtained vibroacoustic signals were processed using software developed by the authors. Spectral analysis was used to identify the frequency range of the signal that showed the strongest correlation with surface quality (6–12 kHz). The conducted studies resulted in relationships for assessing the surface roughness formed during the finishing of shaft-type parts made of St3 and steel 45 steel grades. Vibroacoustic signals were demonstrated to be appropriate for the correction of turning modes based on cutting insert wear monitoring. Thus, the power of vibration signals in the range from 0.001 to 0.015 dB corresponds to the normal cutting-insert wear zone recommended for operation. If the power exceeds 0.015 dB, a transition to a zone of severe wear is observed, which requires stopping machining due to the high probability of defects. Preliminary testing on a batch of parts showed the possibility of increasing efficiency by 15–20 % without adversely affecting the surface roughness of the machined parts. Thus, vibroacoustic signals recorded by an accelerometer during machining can be used to increase the efficiency of manufacturing turned parts on CNC machines and reduce unexpected cutting-insert failures. 

The study aims to develop principles for forming coalitions of prosumers within an integrated energy system for efficient energy supply, substantiate the rules governing their interaction, and create a transparent mechanism for distributing joint gains among coalition participants. To this end, modeling was performed using multi-agent technologies that effectively describe multiple entities with divergent interests. In the present study, these include a centralized energy supply system with large-scale energy sources, individual energy consumers, and prosumers with their own generation sources. Models were constructed based on approaches from the theories of non-cooperative and cooperative games, which determine the actions of participants at different hierarchical levels of interaction within an integrated energy system. Particular attention is paid to the principles of forming prosumer coalitions and approaches to distributing joint gains. For this, solution concepts from cooperative game theory, such as the prenucleolus, modiclus, Shapley value, and tau-value, are used. The problem of interactions among consumers within a coalition was mathematically formulated to implement the cooperative strategies of participants. The developed multi-agent model was used to conduct experiments on the interaction of prosumers in coalitions with various compositions. Cooperative game solutions for distributing joint gains were implemented; the “best” solutions were identified according to a set of criteria reflecting the contribution and interests of each participant. The “best” solutions were demonstrated to vary depending on the coalition configuration. Thus, distribution according to the modiclus is the “best” for a coalition consisting of prosumers that differ significantly in their levels of consumption and own generation. In the case of approximately homogeneous prosumers, the prenucleolus or tau-value is optimal. Thus, the proposed criterion for determining the “best” distribution was used to select the most effective organization of interactions among prosumers within coalitions in the energy system.

This study aims to evaluate the effectiveness of various demand management methods for residential charging stations in reducing peak demand and the extent of distribution network reinforcement needed to accommodate electric vehicle charging infrastructure. The analysis is performed for a 10‑kV distribution network supplying more than 6,000 customers. Maximum electrical loads were determined using simulations that account for the charging behavior of electric vehicle owners, charging station parameters, and the daily load profile of the distribution network. To limit the power drawn by charging stations, a delayed charging strategy was applied, as well as single‑level and two‑level direct demand control schemes. For each demand management method, the resulting load profiles of both electric vehicle charging stations and the distribution network were modeled. The results show that widespread electric vehicle adoption leads to a substantial increase (44 %) in peak load in low‑ and medium‑voltage distribution networks, posing a risk of equipment overload and necessitating significant investment in distribution network reinforcement (approximately 70 million RUB). The examined demand management methods reduced the network peak demand by 13 %, offering an economic benefit by lowering reinforcement costs by up to 66.94 million RUB. The average incomplete charging associated with the single‑ and two‑level control schemes was only 0.93-1.55 %. Overall, demand management for electric vehicle charging stations can significantly reduce the cost of distribution network reinforcement while having only a minor impact on the charging quality of electric vehicles.

The pyrolysis (low-temperature carbonization) of a coal bed was investigated to determine conditions for producing briquettes suitable for use as solid fuel or as feedstock for carbon materials. The study used Cheremkhovo coal (Irkutsk coal basin, Russia) with a moisture content of 10 %, volatile matter yield of 38.7 %, and ash content of 30.2 %. Beds of weakly caking coal were pyrolyzed in a laboratory muffle furnace at 300–400°C and subsequently pressed at approximately 20 MPa. Numerical modeling was used to describe the kinetics of thermal decomposition and heat transfer. Briquettes produced at 300–350°C had a strength of approximately 95%, whereas those produced above 350°C disintegrated during pressing. Briquette strength was found to depend primarily on the thermal state of the coal bed, specifically on the uniformity of heating and the degree of thermal decomposition throughout the bed height. A simplified mathematical model was developed to evaluate the uniformity of heating and decomposition. In a one-dimensional approximation, the model describes heat transfer and a two-stage endothermic overall reaction comprising coal softening followed by conversion to semicoke. An oscillation index was introduced as a numerical criterion that accounts for nonuniformity in the conversion profile throughout the bed height; high index values indicate low expected briquette strength. Qualitative comparison of the experimental data with estimates based on different criteria, including the uniformity of the coal-bed state and energy consumption, showed that the mathematical model adequately describes the thermal pretreatment of coal. The calculations indicate that the highest strength of Cheremkhovo coal briquettes is achieved at temperatures of 300–320°C with a heating time of approximately 1 h. The corresponding energy consumption for briquette production is 2–3 MJ/kg of coal.

This study presents a method for controlling the shape of the spray plume during the atomization of coal-water slurries by introducing helical swirl of the atomizing gas in an external mixing pneumatic atomizer. Coal-water slurries obtained from coal preparation waste were investigated using two processing routes: with and without treatment in a rotary hydrodynamic cavitation reactor. Atomization experiments were conducted on a dedicated test rig modified to introduce air tangentially into the annular channel, thereby producing a swirling flow. Droplet size was measured using interferometric particle imaging, while droplet velocity was determined by particle tracking velocimetry. The experiments were performed at slurry flow rates of 100 and 200 g/s and atomizing gas pressures of 0.6 and 0.9 MPa (gauge). Cavitation treatment reduced the dynamic viscosity of the slurry at shear rates above 50 s–1 and increased the fraction of particles smaller than 100 μm by 10 %. Atomization of the treated slurry produced average droplet diameters ranging from 87.8 to 112.3 μm, which were 29–42 % smaller than those obtained with the untreated slurry. As the slurry flow rate increased from 100 to 200 g/s, the proportion of fine droplets decreased by 5–18 %, depending on the pressure, whereas the fraction of larger droplets increased. The velocity of droplets obtained from the treated slurry was 10–15 % higher than that of droplets produced from the untreated slurry. The introduced helical swirl of the atomizing gas increased the spray cone angle from 21.1° to 25.8°, while causing only a modest (18 %) increase in average droplet diameter compared with straight gas injection. The proposed atomizer modification provides effective control of spray geometry while maintaining acceptable atomization quality. In addition, cavitation treatment significantly improves the rheological properties of coal-water slurries and their atomization characteristics, which is important for efficient combustion of coal-water fuels in power generation systems.

The study aims to review the application of generative adversarial networks (GANs) in power system operation and expansion planning, identifying promising areas for their implementation and future development. The article examines approximately 50 Russian and international publications, analyzing the advantages, limitations, and prospects of the proposed solutions. Additionally, a computational experiment using the PyTorch library was conducted to implement and test a GAN model for generating synthetic hourly solar power profiles. Literature analysis identified two primary applications of generative models in power systems: scenario generation for renewable energy output and nodal loads to support expansion planning, forecasting, and reliability assessment. Conditional generative networks are also shown to be used as probabilistic models for analyzing the significance of influencing factors. In the computational experiment, the generative network model enabled the generation of stochastic daily power output profiles for solar power plants that are indistinguishable from real ones in terms of probabilistic metrics. The study highlights that the primary challenges in using such models are unstable training and the difficulty of applying a single model to simultaneously generate large amounts of data. This review examines various GAN applications and analyzes specific training and application algorithms. Solving the identified issues and training generative networks to address auxiliary tasks in operational optimization represent the most promising areas for further research.

This study evaluates the energy efficiency of combining manual discrete tracking of photovoltaic modules with flat reflectors in micro- and small-scale solar power plants operated in remote northern regions. The study was based on full-scale experiments and comparative analysis of the output characteristics of photovoltaic modules. Experiments were conducted in central Yakutia (Russian Federation) using a laboratory test facility equipped with a flat reflector, weather station, data loggers, and thermal imaging equipment. A method is proposed to increase electricity generation through hourly manual adjustment of the azimuth (from +90° to –90°) and zenith (from 15° to 55°) angles of a rigidly coupled photovoltaic module–reflector assembly. This tracking strategy increased average daily electricity generation by 41.82 %, while the projected increase in average annual generation was 30.88 %, relative to fixed modules. A concomitant 12–13 % increase in the surface temperature of the photovoltaic cells resulted in 23.63 % higher thermal losses, indicating the need for integrated cooling systems in regions with high solar irradiance. A 60-min adjustment interval was found to provide an optimal compromise between energy efficiency and user effort. The effectiveness of the method also varied with latitude: in Arctic regions above 66° N, its principal benefit was the ability to adapt the photovoltaic modules to low solar elevation angles, whereas in southern Yakutia, it maximized peak power output. The results confirm the feasibility of discrete tracking as a means of increasing the capacity factor of solar power plants at high latitudes. In combination with energy storage systems, the proposed approach can provide a high degree of energy autonomy for remote consumers without the capital costs associated with sophisticated automation systems and their vulnerability to the extremely low air temperatures of northern and Arctic regions.

This study presents a detailed analysis of the mechanism of lithium sorption from natural calcium chloride brine with a lithium concentration of 0.24 g/L. Lithium was extracted using a synthesized granular sorbent based on lithium-aluminum layered double hydroxide under static conditions at 25°C. The kinetic data were analyzed using the pseudo-first-order, pseudo-second-order, and Elovich models, as well as the Boyd and Weber–Morris diffusion models. To assess the applicability of the kinetic models, both conventional linearization and rigorous nonlinear regression analysis were employed. The equilibrium sorption capacity of the sorbent was experimentally determined to be 5.5 mg/g. Linearization of the kinetic data using the pseudo-first-order, pseudo-second-order, and Elovich models showed that lithium sorption was best described by the pseudo-second-order model (coefficient of determination R² = 0.9966) and the Elovich model (R² = 0.9847). More rigorous nonlinear regression and subsequent comparison of the Elovich, pseudo-first-order, and pseudo-second-order models identified the Elovich model as providing the best fit to the lithium sorption data. Diffusion analysis of the sorption mechanism revealed two distinct stages. The Weber–Morris model, characterized by two linear segments (R² > 0.98), demonstrated a change in the rate-limiting step: a short initial stage was followed by a longer final stage. The Boyd model (linear relationship, R² = 0.9751) showed that the process was not controlled exclusively by intraparticle diffusion. These results indicate that lithium sorption onto the lithium-aluminum layered double hydroxide sorbent involves a complex mechanism dominated by chemisorption on a heterogeneous surface, with intraparticle diffusion making a substantial contribution, particularly at later stages of the process.

This study presents a thermodynamic assessment of the simultaneous leaching of Au and U from complex oxidized gold-uranium ores with acidic thiocyanate solutions at different temperatures. In addition, the physicochemical conditions required for the subsequent dissolution of gold(I) thiocyanate passivation layers are identified. Variations in the Gibbs free energy of gold leaching reactions were calculated over the temperature range of 298–358 K using thermodynamic cycles of dissolution and complex formation and the stability constants of dithiocyanatoaurate(I), Au(SCN)₂^–, tetrathiocyanatoaurate(III) Au(SCN)₄^–, gold(I) thiocyanate, AuSCN, and all coordination forms of Fe(III) thiocyanates. The behavior of the U(IV)–U(VI) system was evaluated by the conventional method based on differences in the standard Gibbs free energies of formation of the compounds and ions at 298 K. Thermodynamic calculations showed that during thiocyanate leaching, gold enters solution predominantly as the thermodynamically stable Au(SCN)₄^– complex. The greatest driving force for complex formation, accompanied by gold oxidation, was observed in reactions involving free Fe(III) ions and the FeSCN²⁺ complex. At temperatures above 303−305 K, gold undergoes passivation through the formation of AuSCN. Thermodynamic analysis demonstrated that AuSCN can be dissolved by maintaining an excess of SCN^– ions. Analysis of the uranium-containing system showed that the addition of Fe(III) ions as an oxidant promotes the leaching of refractory UO₂, with a Gibbs free energy change of −105.5 kJ/mol. Thermodynamic calculations further showed that under acidic sulfate-thiocyanate leaching conditions, uranium occurs in solution predominantly as uranyl sulfates. Thus, in the acidic sulfate-thiocyanate system, gold forms stable  Au(SCN)₂^–and Au(SCN)₄^– complexes, while thiocyanate is not consumed through complex formation with uranium. The resulting AuSCN films are dissolved in the presence of excess free SCN^– ions, Fe(III) ions, and iron thiocyanate complexes. These findings provide a basis for further laboratory studies of the simultaneous sulfate-thiocyanate leaching of gold and uranium.