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This research aim is to develop a method for modeling the conditions for the critical hydraulic impacts emergence on thermal and nuclear power plants’ pipeline systems pressure pumps departing from the general provisions of the heat and hydrodynamic instability theory. On the developed method basis, the conditions giving rise to the reliability-critical hydraulic impacts emergence on pumps for the thermal and nuclear power plants’ typical pipeline system have been determined. With the flow characteristic minimum allowable (critical) sensitivity, the flow velocity fluctuations amplitude reaches critical values at which the pumps working elements’ failure occurs. The critical hydraulic impacts emergence corresponds to the transition of the vibrational heat-hydrodynamic instability into an aperiodic one. As research revealed, a highly promising approach as to the preventing the critical hydraulic impacts related to the foreground use of pumps having the most sensitive consumption (at supply network) performance (while other technical characteristics corresponding to that parameter). The research novelty refers to the suggested method elaborated by the authors’ team, which, in contrast to traditional approaches, is efficient in determining the pump hydraulic impact occurrence conditions when the vibrational heat-hydrodynamic instability transition to the aperiodic instability.

Studying the problem of diagnosing high-voltage lines is the goal of this research. The high accident rate of overhead lines due to icing and current overloads makes this problem important. Current overloads during distributed power generation lead to overheating of the lines. The goal of the research is achieved due to the fact, that the article notes the relationship between icing and overloads. The necessity of joint solution of these problems and the development of the concept of a multifunctional measuring system is proved. For this, an analysis of the main parameters that determine the mode of operation of overhead lines is carried out. Technical solutions for the measurement of these quantities are considered. The detection of ice formation by comparing the values of dew points and desublimation is described. The calculation of the limiting current load taking into account weather conditions is given. The amount of sagging wires is selected as a universal characteristic of the state of the line. A significant result of the study is the optical method of icing control. This method consists in measuring the coordinates of the line wires through a weatherproof CCTV-camera. To do this, optical tags and a temperature sensor are placed on the wires. The optimal architecture of the measuring system for assessing the climatic impact is given. The significance of the results is that a multifunctional and high-precision system without expensive load sensors is proposed. The conclusion about the importance of the results for building a smart grid is made.

The purpose of this article is to develop a method and algorithm for the calculation of the steady-state mode and static characteristics of the squirrel-cage asynchronous motors that are supplied by a three-phase network with an asymmetrical voltage system. The aim is achieved by developing a method where the mathematical model of the motor takes into account the saturation of the magnetic core and the current displacement in the short-circuited rotor bars. Magnetization characteristics of the main magnetic flux and the leakage fluxes paths are used to account for the saturation. To account for the current displacement in the rotor winding the bars are divided into several layers throughout the height, resulting in a number of windings on the rotor with mutual inductive couplings. In the mathematical model, the processes in the asynchronous motor are described by a system of the nonlinear differential equations of electromagnetic equilibrium, composed in the fixed three-phase coordinate axes. The solution of this system in the steady-state mode is the periodic dependence of the currents, which are determined by solving the boundary problem. For this purpose, their algebraization is carried out by approximation of the periodic dependences at the nodes’ grid of the period of repeatability of the process by the third order splines. The solution of the problem is to determine the nodal values of coordinates on the period from the obtained nonlinear system of algebraic equations. For this purpose, the continuation method and iterative refinement by the Newton method were used. Calculation of the static characteristics was performed by the differential method.

The aim of the work is to increase biogas output and generation of electricity in biogas plants due to the joint fermentation of cattle manure with winemaking waste. To achieve this goal, the following tasks have been solved: the biogas yield from cattle manure with winemaking waste was determined during periodic loading of the digester; based on the obtained experimental data, a mathematical model was calibrated to estimate the biogas yield during fermentation of cattle manure with the addition of winemaking waste. Because of the studies, it had been found that when manure was fermented with part of the water replaced in the substrate 2% of the winemaking waste, the fermentation dynamics in the substrate are similar to the fermentation of pure cattle manure. Biogas obtained by fermentation of manure with the addition of 2%, 6.5% and 13% of wastewater from wine production instead of water in the first day of fermentation either did not burn at all or burned poorly. The addition of winemaking waste to a substrate based on manure in an amount of 13% allows increasing the maximum biogas yield by a third to 1,372 l/(hrkg dry organic matter). The significance of the research results lies in the fact that the use of winemaking waste as a substrate will allow a third increase in biogas output and power generation, and a reduction in the payback period of a 4,4 MW biogas plant using the green tariff to 6,5 years.

The purpose of this work is the theoretical substantiation and development of a practical method for calculating the exchange fund of electrical equipment of an industrial enterprise. The purpose is achieved through the use of separate methods of queuing theory if the flow of applications for repairs and restoration are the simplest. It is confirmed by the results of statistical studies. Therefore, for the mathematical description of the repair problem the authors use the scheme [Mm; Ms; n], which corresponds to the process of death and reproduction. As a criterion for optimizing the exchange fund of electrical equipment it is proposed to use the zero probability waiting for the replacement of a faulty electrical component with a working from the exchange fund. For the case of the simplest flow of applications for service, the authors suggest to use the Peck and Hazelwood tables, which significantly simplify the calculation of the exchange fund for known failure rates and electrical equipment recoveries. For practical use of the proposed method, the authors have developed convenient forms for presenting initial data for calculating the exchange fund, and it is proposed to present the results of calculations in the form of several options for the optimal number of electrical equipment in the exchange fund depending on the accepted level of zero expectation probability, the number of elements from the exchange fund and their recovery time. The proposed method will optimize the exchange fund of electrical equipment and reduce the cost of its formation.

The results of gas current calculations in a flow part in not reversive jet-reactive turbine at pressure upon an input to the turbine up to 10 МPа (earlier calculations were spent up to 0.9 МPа), executed in program complex FlowVision for the first time are presented in the article. The dependences of factors and parameters of efficiency of the jet-reactive turbine (JRT) from total pressure upon an input in the turbine are received. They are exposed in a graphic type. The primary goals of the research were: calculation of parameters of current of gas in a flow part of the jet-reactive turbine by means of program complex FlowVision at pressure upon an input of the JRT from 0.4 up to 10 МPа, the analysis of results of calculation, reception of dependences of different factors from total pressure upon an input in the turbine. The Influence of total pressure on an input in the JRT on various factors, such as: total pressure recovery factor, factor of hydraulic resistance and factor of outflow were investigated. It was discovered that total pressure recovery factor  increases for 27 % at an increase of pressure of an input of the jet-reactive turbine up to 4 МPа. It was determined that the hydraulic resistance factors related to the dynamic pressure at the inlet ξin and the turbine output ξout is reducing at 2.7 and 3.3 times, respectively, with an increase in pressure at the inlet of the jet- reactive turbine to 4 MPa.

The aim of this work is the development and study of a mathematical model of the floating dock initial stability for solving problems of list and trim stabilization. The proposed model allows calculating the change of the parameters of the initial stability of the floating dock (with and without a vessel) for different values of the draft. The initial stability of the real floating dock of the middle class with a carrying capacity of 8500 tons is studied using the simulation model developed by the authors in the FREE!SHIP Plus. With the help of this computational model, the operation of immersion of the floating dock is considered. At each stage of immersion at a certain draft, the parameters of the initial stability of the floating dock are calculated, namely, the values: transverse and longitudinal metacentric heights, centers of buoyancy, centers of gravity, and mass displacement. Corrections of transverse and longitudinal metacentric heights due to changes in the mass of liquid in ballast tanks and the influence of its free surface are also taken into account. Based on the obtained modeling results, the following dependences are calculated: a) moments from list and trim angles at different values of draft, b) moments of list and trim from draft at various values of list and trim, c) angles of list and trim from the fill level of the respective tanks. These dependences can be used for further development of the list and trim stabilization system for the given floating dock.

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(2022). \u041e\u0442\u043a\u043b\u043e\u043d\u0435\u043d\u0438\u0435 \u0433\u0435\u043e\u043c\u0435\u0442\u0440\u0438\u0447\u0435\u0441\u043a\u0438\u0445 \u043f\u043e\u043a\u0430\u0437\u0430\u0442\u0435\u043b\u0435\u0439 \u043f\u043e\u0432\u0435\u0440\u0445\u043d\u043e\u0441\u0442\u0435\u0439 \u0434\u0435\u0442\u0430\u043b\u0435\u0439 \u043f\u0440\u0438 \u0438\u0445 \u043e\u0431\u0440\u0430\u0431\u043e\u0442\u043a\u0435. Research and education, 1(9), 298-302. 14.\tShermukhamedov, A., Azizov, A., Ergashev, N., Shermukhamedov, Y., & Abdukhamidovich, A. K. (2022, June). Substantiation of the parameters of the wheel propeller tread lugs. In AIP Conference Proceedings (Vol. 2432, No. 1, p. 030089). AIP Publishing LLC. 15.\tIbragimov, B. D., Ergashev, N. T., & Shoikromov, S. B. (2022). Study of the effect of a new polymeric anticorrosion coating in transporttechnological machines on noise and vibration. Global Scientific Review, 8, 75-79. 16.\tShermukhamedov, A., Ergashev, N., & Azizov, A. 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Retrieved from https://openidea.uz/index.php/conf/article/view/227"]} : В данной статье сделан анализ физико механических свойств различных категорий грунтов приведены сведения по показателю консистенции различных агрегатных состояний связных минеральных грунтов, по удельному весу твёрдых частиц различных типов грунта, по ориентировочным значениям чисел пластичности и пределов текучести для связных грунтов. Представленны формулы зависимости числа пластичности, пределов пластичности и текучести связных грунтов от процентного содержания глинистых частиц. Приведены коэффициенты для расчета угла внутреннего трения, удельного сцепления, модуля общей деформации. Определены диапазоны изменения факторов при проведении теоретических исследований в данной работе. Определены параметры грунта для разработки математической модели движения пустынного четырехколесного пропашного трактора.