The advantages of using frequency converters are well known. First of all, this is a significant energy savings due to the regulation of the rotational speed of the electric motor. In addition, ensuring a smooth frequency start using frequency converters significantly reduces thermal and mechanical loads when starting synchronous motors with a rotor excitation winding and with permanent magnets. In this paper, the start-up of a synchronous motor with a two-link frequency converter for various types of load was investigated. The following issues were considered: - creation of a three-phase two-link frequency converter model for a synchronous drive; - calculation of the torque on the shaft at rated power, as well as coefficients reflecting the nature of the load; - simulation of the start-up and operation of a synchronous motor and a two-link frequency converter with fan, conveyor and constant shaft loads. In conclusion, the model of a two-link frequency converter with a synchronous motor, which was researched in this paper, can be used in systems where the considered types of loads are used. This circuit has high energy characteristics, reliability and stability, and is also able to reduce the amplitude values ​​of currents and time of transient processes at start-up

Keywords: two-link frequency converter, permanent magnet synchronous motor, mathematical model, reliability, PSIM

This study presents the results of the development of a polymer composite material with good dielectric properties, which allows it to be used in the radio and electrical industries. This material is based on epoxy resin, polyethylene polyamine, hollow glass microspheres and gallium oxide. The use of hollow glass microspheres in the composition in an amount of 5-20 wt. h. reduces the dielectric losses, and the use of gallium (III) oxide in an amount of 5-15 wt.h. it makes it possible to increase the stability of the dielectric characteristics when working in the microwave radio range and reduce the dielectric loss. Studies have shown that a sufficiently effective composite polymer material with high physical, mechanical and dielectric properties can be obtained on the basis of the developed composition.

Keywords: composite material, epoxy resin, hollow glass microspheres, gallium oxide, permittivity, dielectric loss tangent

A model of a household refrigeration machine (BHM) is considered. The refrigerating capacity, thermal load are determined, the compressor and operational parameters are calculated, the cycle of the chiller in p-i coordinates is built.

Keywords: household refrigerator, temperature, refrigerator, heat load, cooling capacity, compressor, heat influx

This paper describes the problems of identifying effective sales channels for services working with a call center. The solution is presented in the form of a multi-level model of sales channels that works with call tracking with a limited number of phone numbers. This approach can be applied in services of small and medium-sized businesses, which cannot afford a large number of phone numbers for call tracking.

Keywords: sales channel, contextual advertising, call tracking, call center, marketing, Yandex Direct, Google AdWords

In this work a breaking of interatomic bonds of kaolinite unit cell under a microwave irradiation was studied. Using density functional theory method (DFT), free energy of the unit cell was computed: without an external field created by the microwave radiation, with the field along (100), and (010) and (001) directions of the unit cell. It was shown that unit cell free energy differences are several kJ/mol. Computational results are backed up by a band structure computation. The conlcution is that there is no bond breaking in the caolinite unit cell caused by the microwave irradiation.

Keywords: kaolinite, microwave field, covalent bonds, discontinuity, ab inito, density functional theory, unit cell, free energy, electronic band structure, clay

Questions of accounting of actors of influence on the investment and construction cycle are raised. An example of the use of BIM-technologies in construction is considered. It describes the solution of some specific problems that arise when maintaining the quality of construction of complex buildings, taking into account the possibility of introducing modern information systems, attention is paid to the peculiarities of improving the quality of work performed.

Keywords: organization of construction; quality of design, quality of construction and installation works, BIM-technology

The study of the internal friction of electrolytic coatings is complicated by the impossibility of obtaining sufficiently massive samples and testing them independently of the substrate, and therefore it is necessary to evaluate the stress state of the sample-coating system. The aim of the work was to find a relationship between the internal stresses arising in the coating deposited on a circular cross-section specimen during internal friction tests using a torsion pendulum. During the analysis of the stress-strain state of the bimallic sample, expressions were found to calculate the maximum and minimum stresses in the electrolytic coating. The mutual influence of the coating material and the substrate was evaluated numerically using the Comsol Multiphysics program.

Keywords: internal friction, internal stresses, torsion pendulum, beam rotation, electrolytic coatings

This article analyzes the sphere of the organization of business collective discussions and identifies key problems in this area, as well as proposes a new method for increasing communication efficiency through the use of special software.

Keywords: networking, collective discussion, communication effectiveness, networking organization, networking app

The article deals with obtaining RDF fuel based on solid municipal waste. The expediency of using this type of fuel in the cement industry is justified, since its combustion in cement furnaces has less impact on the environment due to the high temperature level of the process. The composition of RDF fuel by elements is analyzed. Due to the fact that this fuel from different sources has a difference in the heat of combustion of two times or more, the heat of combustion of RDF fuel for the middle zone of Russia was experimentally determined and its compliance with GOST R 55127-2012.

Keywords: solid municipal waste, MSW, Recycle Derived Fuel, RDF fuel, lower combustion heat, ash content, alternative energy source, colorimetric bomb

This paper presents results of development of heat-resistant dielectric composite material based on epoxy resins to create structural and electrical radio products, coating materials receiving and transmitting radio systems for the aerospace, naval and land equipment. Research results show that when adding 10 wt.h. polyethylene polyamine as a hardener, 10-30 wt.h. polymethylphenylsiloxane as a modifier to ensure homogeneity, 10-40 wt.h.ceramic hollow microspheres and 5-15 wt. h. alumina as fillers per 100 wt. h. epoxy resin can be obtained a material with low permittivity and high thermal stability at 150 °C.

Keywords: dielectric material, polymer binder, epoxy resin, polyethylene polyamine, polymethylphenylsiloxane, hollow ceramic microspheres, heat resistance, permittivity

In this paper, we consider the simulation of a 5.1 kW synchronous electric motor with a two-link frequency converter with a control system that monitors the speed on the shaft in the PSIM simulation environment. IGBT M2TKI-50-12 manufactured by Elektrovypryamitel Saransk were selected for the load current. In this case, the load on the shaft abruptly changed from 1.25 to 2 of the nominal value. Presented are graphs of current, output power, motor speed and torque on the shaft.

Keywords: permanent magnet synchronous motor, PSIM, two-link frequency inverter, spasmodic load variation

The article considers the solution of the problem of distributed control of a group of stepper motors based on multi-channel transceivers. The analysis of literature sources devoted to the development of wireless stepper motor control systems is carried out. The expediency and possibility of distributed control of stepper motors of manipulator links using multi-channel transceivers are considered. It is assumed that there is a need for two-way information exchange between the stepper motor module and the Central control system. The design ratio for the duration of the cycle of the full package of control information with the values of the duration of pauses, switching reception and transmission, the duration of the preamble and the duration of transmission of the address, useful information and checksums of the package. The possibility of increasing the maximum frequency of control pulses transmitted over the information channel when transmitting a sequence of control packets instead of single packets is proved. The structure of the package for controlling the electronic stepper motor driver is defined, including a pointer to the direction of rotation, the duration of pulses and the degree of fractional step. An example of calculation, based on the obtained ratios, of the maximum speed of rotation of the stepper motor shaft for specific models of the engine and the transceiver in the case of a six-channel control system is given. Keywords: distributed control, stepper motor group, control package, frequency of control pulses.

Keywords: distributed control, stepper motor group, control package, frequency of control pulses

This article investigates methods to combine multiple data-driven models for forecasting time series. This is done in order to increase the accuracy of forecasts according to the historical error signal, such that it minimises downstream costs of forecast errors.

Keywords: time series, combination of models, accuracy assessment, forecasting, forecast accuracy

Currently, in the design and manufacture of steel products operating in conditions of heavy impact-abrasive wear, not only material is given, but also the structure of the product itself. One such detail is the friction wedge of a freight wagon trolley. In the presented work, a new design of the friction wedge of the vibration damping unit is presented; technical calculations are carried out on the strength of the presented design. The safety factors of spring suspension are calculated. All calculations were performed according to the standards for the calculation and design of new and modernized railroad cars of the Ministry of Railways 1520 mm gauge. The performed calculations indicate the high performance of the developed design, the obtained values ​​fully satisfy the requirements for such products. The result of the work on creating a new design of the friction wedge of the vibration damping unit is to obtain a patent for utility model No. 194823, a drawing has also been developed (KI-000.00.00.001) and terms of reference for experimental design work (KI-000.00.00.001 TK).

Keywords: friction wedge, vibration damping unit, freight car truck, strength, reliability, durability, calculation of spring suspension, static deflection of spring suspension, coefficient of structural margin of deflection, coefficient of relative friction

The article considers one of the main systems that ensure the safety of workers and passers – by in a dangerous zone-the protective-catching grid. The types of grid systems, basic principles of their operation, and technical characteristics are described. The requirements for the installation and operation of such systems are considered.

Keywords: grids, construction, security, organization, security screens