The use of modern devices and technologies in power supply systems will provide consumers with high-quality energy. Especially effective in this direction will be the construction of autonomous systems using renewable energy sources and local smart grids. The coordinated work of all elements of systems and optimal control of energy flows is solved by mathematical modeling methods.

To assess the operability and technical condition of low-voltage devices, it is proposed to use the resistance of contact connections. The probability of failure-free operation is proposed to be evaluated by the dependence of the resistance of the contact connections of the apparatus on the number of switching operations. As a result of wear, the initial value of the contact resistance of the switching device increases and reaches a critical value at which the switching device fails. Due to the fact that in the process of research there are both complete contact failures and short-term switching of only one time, the contact resistance is exceeded by the contact resistance of the threshold value. For magnetic starters, circuit breakers and contactors, based on the results of the experimental studies carried out, in order to achieve the critical resistance value of the apparatus, аn average of three times the initial resistance. At the same time, the quantitative characteristics of the functioning efficiency are determined by the methods of probability theory and mathematical statistics. The set of the obtained quantitative indicators allows to determine the actual level of reliability of contacting, and also extends the possibility of predicting performance ratings in the design.  In the present article, a method for the complex evaluation of the efficiency of low-voltage apparatus has been developed and the laws of the change in the resistance of contact connections and the probability of failure-free operation of low-voltage switching devices have been revealed, depending on the operating conditions.

The results of numerical and experimental study of wall friction and heat transfer in a short cylindrical channel are presented. Hydrodynamic and thermal characteristics of nonstationary high-temperature gas flow are determined. The results are summarized in the framework of boundary layer theory.

The article considers the layout solutions of the electrolysis shop of the hydrogen superstructure outside the territory of the nuclear power plant. To do this, an annual risk assessment was carried out taking into account the reliability and explosion risk for 1-4, 8 and 16 separate electrolysis shops installed on the site of the hydrogen superstructure. When taking into account equipment breakdowns, with possible explosions and fires in electrolysis plants, the risk due to fires and explosions was several times lower than the risk associated with equipment failures. Calculations showed that the transfer of electrolysis plants to increased hydrogen productivity in the event of failure of one of the cells is the best option in comparison with the reduction in the generation of electricity at the steam turbine installation of the hydrogen superstructure.

In order to increase the operating efficiency of solar power generating system its absorbing surface must be continuously turned towards the Sun. Modern Sun tracking systems are analyzed. Operation of solar air wall-type collector is considered. Collector’s absorber plates were situated in two ways – horizontally and vertically. Operation of the collector with horizontally situated plates is to turn of the plates towards the Sun according to solar altitude angle. Vertically situated plates position depends on solar azimuth angle. Cross shading of the absorbers plates during Sun tracking is calculated. To estimate the collector efficiency its operation within two days of the year (1.01.2016 and 11.06.2016) is studied. In order to compare the collectors’ characteristics with different types of the absorber the mathematical model is built.

The application of autonomous electric power equipment having in their composition parallel operating diesel-generator sets on the basis of synchronous generators is considered. The problem of existence of exchange power fluctuations in such technical systems is described. A mathematical model has been developed that makes it possible to carry out investigations of an autonomous electric power equipment. The technique for constructing maps of the amplitude of the exchange power fluctuations, from the backlash gaps in the speed control circuits of diesel generators is obtained. The use of such cards makes it possible to introduce recommendations on limiting the amplitude of exchange power fluctuations to normative documents, both of a general nature, and specifically for certain types of equipment. In the same way, the cards make it possible to determine the gap gaps existing in the frequency control loop from the measured amplitudes of the exchange power fluctuations. 

The article considers the problem of reliable evaluation of flicker in electrical networks. The technique for calculating the normalized frequency characteristics of the instrument for light sources with different sensitivity to voltage fluctuations is presented, which is aimed at improving the standard methods for estimating the flicker. A technique for the normalization of the flicker is
described on the basis of the data of the estimated estimation of the voltage fluctuations in the electric network. 

Now a number of the leading firms work on creation of an automobile autopilot. The authors of the presented article offer to complement the system of an autopilot with the control system of the car technical condition. The developed hardware and software complex allows working with virtual mathematical model of the gas engine of the KamAZ truck and can be recustoized under different modifications of gas and diesel engines. At the same time by means of this complex there is an opportunity to reveal the latent defects of a control system and to reduce labor input of calibration procedures. The hardware and software allows testing electronic control units in standard and emergency operation modes of sensors and actuators, thereby providing compliance to the modern Russian and international requirements to control systems of cars.

 An imbalance appears during the manufacture, operation and maintenance of power equipment. The rotor imbalance arises due to the unbalanced masses of the rotor which leads to the emergence of variable loads on the supports and bending of the rotor. The dynamic balancing of the rotor on the balancing machine is the way to avoid the negative effects of centrifugal forces. The balancing machines in resonant and soft-bearing modes are usually used on modern production. However, these methods of balancing has a number of shortcoming, which can be solved by using the hard-bearing method. For example, an ability of balancing of products with huge imbalance and increasing the accuracy of balancing. 

Application of soft-bearing balancing method needs to be added in other ways, taking into account high reqiuirments of the power equipment. A model of a hard-bearing balancing machine was designed for balancing rotors and rotating elements of power equipment. The Autodesk Inventor CAD software was used for modeling of the balancing machine and the rotor. 

The modal analysis was conducted by using the block method of Lanczos on the basis of the ANSYS system. The main assumption during the modal analysis process was that the form of free fluctuations is calculated in relative units and does not allow to determine absolute shifts. The natural oscillation frequencies of the 3D models of the balancing machine bed and the rotor of the gas turbine engine 16M were calculated to determine the informative frequency range that the rotor should be hard-bearing balanced. 

This article studies problems of forecasting of noise pollution by thermal power plant equipment, industrial boilers, etc. An acoustic model of a residential area, exposed to power plant equipment noise nuisance, has been developed by means of AWM “Acoustics” software using obtained data. Practical application of the experimental-theoretical model for the noise field was demonstrated for efficiency estimation of the proposed engineering solution to noise reduction.

The article presents the methods and installations of control supports tubular rods used in power construction when exposed to static and dynamic loads. Test methods are described.

The article considers a model of supercritical СО2 ‒ extraction technology of ethylene oxide emission from its aqueous solution, which is proposed to replace energy consuming desorption process. The possibility of using normal alkanes as modifiers of the main extractant is considered. A comparative analysis of the energy consumption ofsupercritical and traditional technologies is carried out.

Methods. The Hysys program was used to model the processes.

Results.Was simmulated the extraction process of ethylene oxide separation from its aqueous solution using as an extractant pure and modified with propane, n-butane, n-pentane supercritical carbon dioxide supplemented with further purification and concentration of the desired product.The results indicate the inappropriateness of using n-butane and n-pentane as an additive to carbon dioxide. Comparison of three technological schemes (traditional and two extraction schemes with pure and modified carbon dioxide) shows that the energy consumption for heating the rectification columns is significantly lower in the case of SC-CO2 extraction technologies (115 MW ‒ traditional technology, 36 and 79 MW for SC ‒ CO2 extraction technology without additives and with the addition of propane, respectively), while the combined capacities of pumps and compressors were the least for traditional technology. But, since the degree of extraction of ethylene oxide in the extraction scheme with the addition of propane turned out to be practically equal to unity (0.996), the considered energy indices, referred to the kilogram of the product obtained, turned out to be the best for this scheme.

The article is devoted to the design of optical device ‒ phase isotropic corner reflector, which may find application as a mirror in the fiber-optic converter. The use of phase-isotropic elements will reduce the effect of a light signal phase shift on reflection from the mirror mounted on the end of the fiber sensor. The work analyzes the existing phase devices and suggests a device using real film-forming materials, the angle of incidence of radiation, and the materials of the prism.

The synthesized sample of covellite was investigated by NQR 63,65Cu methods. The experimentally determined values of the quadrupole frequency νQ and the asymmetry parameter η have been used to study the distribution of electron density in the region of the quadrupole nuclei in position Cu1. It is found that Cu-S bond in position Cu1 is ionic, and the gap LUMO-HOMO decreases with increasing temperature.

The Pb-Se film systems were obtained by solid-phase synthesis and investigated by Xray diffraction and X-ray photoelectron spectroscopy, electron Auger spectroscopy. It was found that the films are heterogeneous in structure and composition. To study the structural features under the influence of temperature, Raman spectra of samples at temperatures of 300 K and 373 K were investigated.

One of the perspective applications of pulsating combustion is the utilization of industrial waste. There is a mathematical model and the results of calculating the frequency and amplitude of acoustic gas oscillations in a Helmholtz resonator type device using solid fuel. In this paper, pulsating combustion is considered as a result of the interaction of acoustic oscillations with the process of heat release in the combustion zone. It is shown that the frequency and amplitude of gas oscillations, the amplitude and phase of the heat release rate pulsations, the acoustic energy generated in the combustion zone are interrelated quantities.