The paper presents studies of the system "induction generator-induction motor" with parametric asymmetry on a mathematical model to determine the quality of generated electricity in load operating modes. A mathematical model of the "induction generator-induction motor" system has been developed taking into account losses in steel and parametric asymmetry. The analysis of the transient characteristics of an induction generator when a motor load is connected in symmetrical and asymmetrical modes of operation is carried out. The results of changes in the main characteristics of an induction motor at various degrees of parametric asymmetry in the generator are presented. The quality of the generated electricity was analyzed based on the calculations of the unbalance coefficients for each of the operating modes. The assessment of the thermal state in steady-state conditions was carried out using an equivalent thermal equivalent circuit. Thermal transients were investigated when starting an induction motor from an autonomous energy source based on an induction generator. On a thermal mathematical model, the study of the effect of the output voltage asymmetry on the heating of the connected induction motor was carried out. It is shown that the asymmetry of the output voltage of an induction generator reaches 3–10 % and causes overheating of the windings in excess of the permissible values. A regression model has been developed for studying the operating conditions of an induction motor when powered by an induction generator with an asymmetry of the stator windings. The use of the obtained equations will make it possible to determine the most rational combination of factors affecting the heating of the stator windings of induction machines, in which they will not overheat above the maximum permissible temperature values of the corresponding insulation classes

Three-phase asynchronous motor with a short-circuited rotor has been described with the help of a model convenient for the analysis of changes of its power indices in terms of different values of all the indices of supply voltage quality. Mathematical model of electromechanical converter with the power of 11 kW has been verified based upon the results of industrial experiment in the workshop of “Ukrspetsservis” Ltd. While checking the validity of the model, the obtained values of relative mean square error of modeling make it possible to be used for the purpose of computational studies of asynchronous electric motor energy efficiency.

The object of this study is a reinforced three-layer transport pipe, which is subjected to the joint action of ambient temperature and static loading of the road subgrade soil. The analytical model for assessing the stressed-strained state of reinforced three-layer pipes, under the combined action of temperature and static loads, has been improved using the theory of elasticity. The stressed-strained state of the reinforced pipe was assessed taking into account the values of the joint action of temperature and loads from vehicles, the physical and mechanical parameters of structural materials, and the geometric parameters of the pipe. As a result of the calculation of the reinforced multilayer pipe, it was found that the maximum movements that occur on the outside of the defective pipe are 0.64 mm, the metal pipe – 0.75 mm, and in the concrete mortar (fine-grained concrete) – 0.69 mm. It was established that under the combined action of ambient temperature and static loads from the road subgrade soil, ring stresses are maximum. They are 151 MPa. Axial stresses are also high – 141 MPa. At the same time, the maximum radial stresses are the smallest – 37.4 MPa. It has been established that a small difference in displacements occurs on the contact of structural materials of the reinforced pipe. However, the magnitude of the stresses is high. The maximum difference in ring stresses was 73 MPa, while the difference in radial and axial stresses was up to 1.0 MPa. It has been established that to restore the bearing capacity of damaged reinforced concrete pipes, it is possible to use the repair technology by the method of "sleeving". It involves pulling a metal pipe into the middle of the layer damaged with concrete mortar remaining between the concrete defective and the new metal pipes.

The article presents the calculation of the transfer function of the DCM-30-N1-0.2 micromotor DC, obtained a transcendental system of equations for determining the duration of the quasi-optimal control intervals and the dependence of the first control interval on the specified overshoot. The obtained dependence can be used in the engineering methodology for the synthesis of quasi-optimal control and the choice of actuators of the automatic control system.

The promising potential of porous metallic materials for railway applications (e.g., conductive materials, materials for braking systems) is due to their unique combination of low density, high specific surface area, and high energy absorption capabilities. Porous multi-phase silicide coatings (FeSi, Si₂CN₄) provide a synergistic effect, doubling surface hardness and establishing a stable diffusion barrier. The article proposes a comprehensive approach to replacing materials for critical railway transport components, involving the development of a base material and a barrier coating. The use of widely available induction-melting components to produce a base material with superior mechanical properties is demonstrated. The material exhibits high static strength and hardness while maintaining acceptable impact toughness and ductility. To enhance wear, corrosion, and scale resistance, technology for forming a barrier layer via silicide coatings is proposed. The coating formation technology enables the regulation of porosity through the formation of nitrogen-containing phases. It is shown that pores can serve as “containers” for fillers that impart functional properties to the coatings (e.g., adjusting the friction coefficient or electrical conductivity). The new base material–barrier coating system can serve as a foundation for the sustainable production of critical rolling stock parts and other devices for railway transportation systems.

The paper deals with development of the mathematical model of the two-mass electric drive of a direct current of the electric locomotive with the observer of a full order. The model provides an opportunity to study the change in the ratio of the moments of inertia of the two masses of the electric drive in order to reduce speed fluctuations and inconsistencies in the speeds of these masses. The observer estimates the speed on the basis of information about the supply voltage and motor current. Instead of directly measuring the speed, an observer is used, who uses the measured armature current and supply voltage to change the task to speed. As a comparison, the classical model of subordinate coordinate control for a two-mass electric drive is considered. The disadvantages of the latter are the complexity of calculating the parameters of the links during debugging. Identification and description of the load moment is carried out by a system of differential equations. Reproduction of the vector of coordinates of the system and the vector of perturbations (load moment) is carried out by the observer with an error in the steady state. To compensate for it, the load torque signal in the static is fed to the input of the speed circuit through the debugging link. The results of research on the mathematical model, with its appropriate adjustment under the conditions of a particular electric drive, can significantly reduce the impact loads on the electric drive by accurately matching the speeds of two masses and from a practical point of view provide information on calculations of the kinematic circuit and selection of optimal gear ratio.