We investigate the possibility of using induction currents for improving the reliability of thermal power plants by increasing the corrosion resistance of internal surfaces of power-generating equipment, such as heating surfaces of boiler units. Corrosion resistance can be enhanced by improving the strength of an oxide film formed during passivation (oxidation). In this work, the oxide film strength was increased by electrochemical passivation of metal surfaces with induction currents. Using the method of multidimensional mathematical modeling of multi-parametric and multi-functional processes, we established that, for a continuous-loop economizer of a steam boiler comprising steel pipes with an inner diameter of 32 mm (24 coils operated simultaneously), an aqueous oxidant (oxygen) solution should be passed through the entire system of pipes for 4 h at an alternating current of 25 A. Under this treatment, oxygen should be added into the aqueous solution at a temperature of 130–450°C, an oxygen concentration of 1 g/kg, and a water flow rate of 0.5–5.0 m/s. Treatment intervals should be determined depending on the operating conditions of the equipment: reset, shutdown, or preservation. The efficiency of the method depends on the electric current passed over metal surface, treatment duration, oxidant concentration, as well as the type and size of the treated metal surface. The proposed passivation method can be used in both drum boilers and single-pass boilers. For example, it is recommended that passivation of water walls be carried out during boiler warm-up operation at 30–40% of boiler load, as well as passivation of superheat surfaces of boiler units and economizers. Therefore, the use of electrochemical passivation can increase the corrosion resistance of metal surfaces of power-generating equipment at thermal power plants.

In the present work, engineering decisions for combined ground-fault relay protection in 6–10 kV power grids are addressed. For objects in electrical grids having a voltage of 6–10 kV, simple relay protection was used: overcurrent protection and current cutoff. The most common algorithms for single phase-to-earth fault relay protection were analysed and compared. The modelling allowed a scheme for automatic transfer switch to be designed. Operation algorithms of relay protection and automatics were established, considering the properties of an electrical grids section and the characteristics of possible operating conditions. In 6–10 kV electrical grids, an increase in the damage rate of cable lines with outdated thinned insulation was revealed. It was determined that long-term grid operation under a single phase-to-earth fault should be avoided since double earth faults may occur due to an increase in the voltage of healthy phases relative to earth by √3 times. The calculations performed to evaluate selectivity and sensitivity of the current protection of selective zero-sequence showed limited application (due to the insufficient sensitivity) of such protection from single phase-to-earth fault in some cases. The advantages of circuit designs, which use electromagnetic and inductive relays as protection fault detectors, and advanced compact elements in the form of microcircuits with electronic interconnection as logical elements, were investigated. It is established that the proposed solutions can be used by energy providers to increase the reliability and fail-safety of 6–10 kV distribution networks with the minimum capital expenditures to relaying systems. The presented analysis of systems and devices for phase-to-earth fault relay protection showed that power grids having isolated neutrals are the most problematic in terms of maintenance. Simplified circuit designs for combined protection circuits can be used for facilitating the maintenance of relaying devices and automatics due to their openness.

This work aims to establish a technology for conducting a comprehensive assessment of the impact of energy facilities on the environment. The proposed strategy combines regulatory methods for calculating pollutant emissions and dispersion, as well as the laboratory findings on pollutant content in snow samples. To assist the technology, a scientific prototype of an intelligent decision-making support system known as WIAIS (Web-oriented Impact Assessment Information System) was developed. The proposed technology includes three principal stages: calculating the quantitative indicators of pollutant emissions, calculating the pollutant dispersion in the atmosphere, examining snow samples for the pollutant content and comparing them with the obtained results. For practical evaluation of the proposed technology, a computational experiment was performed, which assessed the impact of emissions from the boiler plants located in the Baikal natural area and powered by different types of coal. The testing was performed using the data on 48 boiler plants of various installed capacities having different equipment and located all over the Baikal nature area. Data on the main pollutants emitted by energy facilities (sulfates, nitrogen oxides, solids) were obtained. Quantitative indicators of pollutant emissions were established; thus, the total volume of pollutants amounts to 18.33 thousand tons/year. Furthermore, the largest sources of pollutants were identified, including boiler plants in Slyudyanka, Elantsy settlement, Severobaikalsk, and Nizhneangarsk settlement. Therefore, the proposed methodology can be used for environmental assessments of the existing power plants, as well as for designing new power facilities and developing recommendations for reducing pollutant emissions.

This study investigates the effect produced by various types of cloudiness on the functioning of a photovoltaic system in the central part of the Republic of Sakha (Yakutia). The electric power efficiency of the photovoltaic system under various cloudiness conditions was assessed using graphical interpretations, measuring and recording devices, as well as a description of the procedure for conducting experimental work. The average indicators of a decrease in the electric power efficiency of the photovoltaic system were determined using patterns for a certain type of cloudiness. A specific cloudiness type was identified by performing measurements and calculating illumination ranges, taking boundary conditions into account. These studies were carried out during the summer period of 2021 using the facilities of the mobile test site of the V.P. Larionov Institute of the Physical-Technical Problems of the North of Siberian Branch of the Russian Academy of Sciences located in the central part of the Republic of Sakha (Yakutia). Control parameters of alterations in the generating capacity of the photovoltaic system were obtained for 10 types of cloudiness. The obtained parameters can be used when modeling operational processes and performing engineering calculations of the operating modes for solar power plants. According to the results, during the operation of photovoltaic systems under various types of cloudiness, the decrease in the generating capacity of the installation can vary within 8–95% relative to the generating capacity indicator under clear weather. The obtained indicators of alterations in the generating capacity of a photovoltaic system under various cloudiness conditions can be applied for developing a methodology for assessing the effect of cloudiness and its types on the carrying capacity of solar beams falling on the photovoltaic panel surface, as well as to more accurately determine the energy potential of solar generation in a certain area.

The study investigates mechanical, thermal, chemical, electromagnetic, and nuclear types of energy from the standpoint of organization of matter in order to establish a connection between them. In this regard, a calculation and comparison of the energy potentials for various levels of matter organization were performed. For mechanical energy, the potential energy and the energy of a steel disk at a rotation frequency of 100,000 rpm were considered. The potential of thermal energy was discussed using the example of a steel sample heated from 20 to 1,400C. For chemical energy, the most common combustible element in technology – carbon – was considered. The energy potential of electromagnetic energy was estimated by determining the total charge of all electrons in 1 kg of iron. For nuclear energy, a calculation of the energy released during the decay of 1 kg of U235 was carried out. A dependence of the energy potential degree on the level of matter organization was established. The possibility of using the energy potential of the next level of matter organization was considered. Patterns of the levels of matter organization were revealed. Despite the fundamental nature of the material presented in this article, it is aimed at a specific practical application in a device developed as part of a doctoral dissertation by one of the authors on the topic “Cogeneration thermal and power complex combining the principles of energy transformation”. A classification of energy forms in accordance with the levels of matter organization was carried out in the framework of identifying the general principles and patterns of using low-potential sources of various energy forms. This classification allows a new thermal transformer and a thermal and power complex to be created. The initial theoretical studies carried out by the authors will subsequently form a basis for the creation of various energy transformers capable of operating with several types of energy in one device.

The present work discusses the development of algorithms for power controller autotuning under normal operation in power units of local energy systems having low synchronous generation, which can operate in stand-alone and parallel mode with the external power grid. The power controller of a power unit is tuned in the course of routine operation following the quality indicators of recorded transients under several load commutations upon a varying amplification factor. The amplification factor for each control channel is optimised by a function that approximates the dependence of the transient characteristics on the value of this factor, including the diversity of processes and mode disturbances during power surge/shedding. The sum of weighted overshoot and process duration values is used as a process quality indicator. Owing to adaptation, the controller automatically tunes itself over time, and the control quality improves. This article presents algorithms for autotuning the power controller when regulating frequency and interchange overcurrent under isolated and parallel operation mode of the MiniGrid, respectively. Unlike frequency controller, when the interchange overcurrent controller is autotuned by transient functions associated with load commutations, the algorithm filters out high-frequency power variations resulting from electromechanical oscillations. The simulation results of autotuning the power controller for an elementary scheme, having one generator, confirm the efficiency of the presented method and algorithms. The proposed method of autotuning frequency and interchange overcurrent controllers appears promising for technological enhancement and use in MiniGrid power control systems.

The goal is to propose an effective method for locating a fault segment in urban power distribution networks. Urban distribution networks have multiple outgoing lines, switches with multiple connections and have variable topology characteristics. It is found that the fault location method based on matrix algorithm has low adaptive capability and fault tolerance when dealing with complex and variable topology. Therefore, this paper proposes an efficient fault segment location method based on special fault indicators, which can significantly improve the accuracy and reliability of fault location. Accordingly, to improve the accuracy and reliability of fault location, a fault segment location method based on fault marking is proposed. The approach proposed in the paper relies on the analysis of the incident matrix, which describes the relationship between nodes and branches, and allows the use of graph theory. The branch state vector is added to obtain the adjacency matrix, which allows to describe the state of change in the dynamics of the distribution network topology. In the next step, a set of nodes and branches, which reflect the incoming and outgoing interconnections of the nodes, is established based on the selected direction of the network binding. According to the direction of the node fault current, the suspicious branches are identified and labeled to indicate the fault. By cumulative calculation and analysis of the labels, the target branches are screened out and the faulty sections of the city power supply network are identified. The results of the case study conducted in the paper show that the proposed method has good adaptability to the variable topology and increases the fault tolerance and accuracy of the developed matrix algorithm. The topological operating state of the network can be changed by controlling the switches to optimize the operation and improve the reliability of the power supply. Thus, the algorithm for fast and accurate fault location is of great importance for improving the safety and quality of urban power supply.

The study aim was to develop a 3D model representing the aircraft air conditioning system with the purpose of performing a numerical experiment in an automated environment of engineering analysis. The completeness of this model was associated with the required result of the numerical experiment. During the experiment, we simulated conditions for the flow of aerodynamic processes in the vicinity of the louvre integrated into the fuselage skin at the point of communication between the air conditioning system and the external environment. Of particular interest was that part of the air conditioning system, which directly affects the louvre strength. The Siemens NX computer-aided design system was used to form a digital copy of the original. The toolkit of this system allows high-precision geometric models to be designed. As a result, a 3D-model was obtained applicable to simulate external and internal aerodynamical processes in the digital environment of engineering calculations for evaluating the strength parameters of the studied part. This model is a combination of geometric objects formed by a set of assembly units. In particular, such elements of the air conditioning system as the cooling turbine, radiator, and valve, are considered. In order to recreate the complex geometry of the original assembly parts of these units, an algorithm for selecting and performing typical operations of the Siemens NX system was developed and optimized for constructing correct 3D models. The constructed 3D model of the aircraft air conditioning system can be used when simulating external and internal aerodynamical processes affecting the louvre strength in the digital environment of engineering calculations. The proposed model allows users to study the structure of aircraft air conditioning systems.

We investigate the kinematic characteristics of ultrasonic surface-plastic deformation when the oscillations are introduced in the direction tangential to the treated surface in order to assess the potential of this method for treating parts made of metals and alloys of various hardness. The kinematic parameters (trajectory, velocity, acceleration) of ultrasonic surface-plastic deformation were calculated in a rectangular coordinate system. Analytical dependencies were obtained for the trajectory length, resulting velocity, and acceleration as functions of the constituent types of motion (rotational, translational, oscillatory). The obtained equations and their graphical solutions allowed us to establish that, under ultrasonic surface-plastic deformation, the indenter moves along a complex trajectory with a variable velocity and acceleration. It is shown that the translation of ultrasonic oscillations to the indenter determines the complex nature of its movement, which differs significantly from that in the diamond burnishing method. In this case, the process parameters (velocity and acceleration) change according to a cyclic (sinusoidal) law, the periodicity of which depends on the frequency of ultrasonic oscillations and determines the final state of the treated surface. According the obtained results, the change in the input direction of ultrasonic oscillations (from normal to tangential) ensures the possibility of changing the contact condition from cyclic to constant, thereby affecting the deforming force during processing. It was found that the angle of oscillation input relative to the main velocity vector is a technological parameter significantly affecting the kinematic characteristics. An assumption is made about the possibility of using the tangential pattern of ultrasonic surfaceplastic deformation for parts made of metals and alloys of various hardness.

The present work aims to improve the existing technology of reaming bores in hybrid stacks containing a composite material interlayered with titanium and aluminium alloys. The study was conducted using statistical approaches at the stages of experimental design and data processing in the Statistica 6 and Microsoft Excel 2010 software. The bore roughness was measured using a Taylor Hobson Form Talysurf i200 contact profilometer. The height of the tool build-up edge was investigated using a Bruker ContourGT-K1 optical profilometer. Bore diameters were determined using a Carl Zeiss Contura G2 coordinate measuring machine. An experimental study was carried out using an Atlas Copco PFD-1500 automatic feed drilling unit and a 14 mm MAPAL reamer with a replaceable head. A methodology for a comprehensive experimental study of boring and reaming processes in the “OT4 titanium alloy - VT6 titanium alloy - polymeric composite materials - VT6 titanium alloy - 1933 aluminium alloy” hybrid stack was developed and implemented. It was found that the most significant factors affecting the parameters of bore accuracy, in particular, the deviation from the true bore longitudinal section profile, include the cutting speed in the first and the second degree, as well as the feed. The optimum cutting modes are a cutting speed of 7.24 m/min, a feed of 0.27 mm/rev and a machining allowance of 0.5 mm. As a result, the time of reaming one bore is reduced by 4.6 times. The optimum cooling method, ensuring the increased accuracy and reduced roughness of the bore in the aluminium alloy layer, is cooling by carbon dioxide at a temperature of -56.5°C. As a result of experimental works, basic laws governing the boring and reaming processes in multicomponent hybrid stacks composed by carbon-fibre-reinforced plastics with titanium and aluminium alloys were investigated.

In this work, we analyse and structure the information on the distribution of noble metals during pyrometallurgical processing of copper-sulphide and copper-nickel concentrates, available in domestic and foreign scientific sources. The data on the influence of oxygen partial pressure in the system and, consequently, the matte composition, process temperature, and the phase composition of slag on the distribution of platinum group metals, gold, and silver between the smelting products were analysed. Broad-ranging information on the distribution of the examined metals between matte and slag in the processing of copper-sulphide and copper-nickel concentrates was studied. It was established that the distribution of noble metals between the products of smelting using modern analytical methods is still in its early stages. Contradictory information on the behaviour of gold, silver, and platinum group metals during the pyrometallurgical processing of copper-sulphide and copper-nickel concentrates is presented in literature due to the variations in the experimental procedures, preparation, and analysis of test samples, and, as a result, further interpretation of the obtained results. Furthermore, no data on the influence of such technological parameters as magnetite content in the slag phase, the relationship between copper and nickel in the initial furnace charge and obtained mattes on the distribution of gold, silver, and platinum group metals between the products of smelting are available. In addition, no information on the distribution of noble metals during the pyrometallurgical slags depletion obtained in oxidative smelting of copper-nickel production has been published. Thus, it was decided to perform further research on establishing optimal technological conditions for oxidising smelting of copper-sulphide and copper-nickel concentrates, as well as pyrometallurgical depletion of slags, allowing for the highest extraction rates of noble metals into the target product.

The present work addresses the problem of improving the percolation properties of heap leaching piles of clay, slime-oxidised and mixed ores. These ores are prone to colmatation, which hinders percolation of the solution through the ore layer. Laboratory tests on percolation leaching were carried out using a 2 m column having an internal diameter of 190 mm, loaded with 89.42 kg of ore material having a grain size of -55+0 mm. In order to eliminate colmatation, the ore layer was divided into two equal parts by a drainage layer of polystyrene foam. The research object was ore material extracted from the northern Nurkazgan deposit (Karaganda region, Republic of Kazakhstan), in which copper is present in the form of sulphide (53.48%) and oxidised minerals (46.52%), including 23.5% of chrysocolla. The mineral composition of a test sample determined by optical and electron microscopy, X-ray diffraction, local X-ray spectral, X-ray fluorescence and inductively coupled plasma mass spectrometry was characterised by 93.78% of rock-forming minerals, 53.23% of which comprised layered silicates, namely, mica, chlorite and kaolinite. Ore mineralisation was characterised by both sulphide (copper sulphides, pyrite) and oxide (malachite, iron hydroxides and manganese oxides) phases. The content of easy-sliming minerals equalled 56.30%. Prior to leaching, moisture saturation during the period of one day was carried out. The ore was top irrigated with a solution of sulphuric acid having a concentration of 60 g/dm3. Pregnant solutions were processed following a sorption method (sorption/desorption–electrolysis). The copper extraction into the solution yielded 60.04% with a sulphuric acid consumption of 50.0 kg/t ore at an average irrigation rate of 10.58 dm³/(m²h) or 0.1058 dm/h per clear opening. Therefore, heap leaching of ores at a layer height of lower than 1 m can be performed following the "leaching–extraction/re-extraction or sorption/desorption–electrolysis" scheme.