This article presents an efficient method for controlling the speed of asynchronous electric drives through the synthesis of optimal laws governing stator current management. It introduces an algorithm that accounts for constraints on stator current values and minimizes electrical losses in the stator coils. Optimization is achieved using an integral criterion incorporating both energy loss reduction and deviation from the specified speed. Formulated as a conditional variational problem, the solution employs Pontryagin's maximum principle. A practical realization scheme for the regulator is proposed, which implements the energy-saving control strategy under established current constraints. Experimental results confirm the efficacy of the suggested method, demonstrating substantial reductions in energy consumption and improved drive dynamics. These findings are particularly valuable for engineers specializing in electrical engineering and researchers involved in designing modern automated electric drives.

Keywords: asynchronous electric drive, energy-efficient control.

This article discusses the types of existing fiber clamps and their features. A new S-shaped fiber clamp has been developed and manufactured to securely fix the fiber under high loads, and options for further design improvements have been considered.

Keywords: clamp, fiber, VBR, fixation, fiber clamp, retainer, fiber retainer.

The presented experimental evaluation confirms the high efficiency of boron arsenide material for heat removal from the active zones of computing modules. It has been demonstrated that the material retains its thermophysical characteristics during prolonged operation. The obtained results indicate the promising use of boron arsenide as heat sinks in computing systems and their components.

Keywords: experiment, thermocouple, boron arsenide, computing systems, temperature, reliability, cooling system, microchip, methodology.

The processes of charge carrier transport in transparent electrodes based on doped oxide layers, as well as in multilayer structures with spatial separation of regions with high doping levels and high mobility, are analyzed. It is shown that charge carrier transport in polycrystalline doped oxide layers is largely determined by the processes of oxygen adsorption-desorption from crystallite surfaces at intergranular boundaries. It is demonstrated that the formation of multilayer periodic structures with embedded pairs of ZnO/Al₂O₃ layers leads to the formation of intermediate conductive phases at the boundaries and an increase in the structures' electrical conductivity. Computer simulation of charge carrier transport in periodic structures with embedded ZnO/ZnMgO/AZO layers was performed. Pathways for improving the characteristics of homogeneous doped TCO layers and conductive multilayer structures during low-temperature synthesis are considered.

Keywords: transparent electrode, transparent conducting oxide (TCO), X-ray photoelectron spectroscopy (XPS), segregation, impurity segregation, periodic structures, modulated doping, computer simulation, resistivity, mobility.

The work is devoted to the description of a complex of special technological equipment, which was created on the basis of the MOSCOW magnetic observatory and is intended for conducting climatic and metrological tests of sensors of quartz analog and digital magnetovariation stations.

Keywords: magnetic field, magnetic measurements, component measurements, quartz magnetovariation stations, quartz sensors, test benches, metrology.

The article provides an overview of standardized methods for monitoring the operational condition of engine oil, as well as new promising approaches based on advanced scientific and technical results. The methods are classified according to the conditions of use – laboratory, field, operational – and grouped by controlled characteristics. Technical solutions suitable for different application conditions are provided for each characteristic. In conclusion, the applicability of the considered methods as the basis of technical solutions for operational monitoring of the engine oil condition in real time is evaluated.

Keywords: engine oil, engine oil analysis, engine oil diagnostics, engine oil monitoring, engine oil condition, standardized methods, laboratory methods, field methods, operational methods, engine oil contamination, engine oil fluorescence.

In this study, a steel sample was subjected to high-cycle fatigue testing with crack growth analysis and subsequent fracture. The microhardness and elastic modulus of the material were then measured in various regions via instrumented indentation method. Hardness was found to increase almost twofold near the edge of the damaged region and decrease slightly within the sample surface. Elastic properties, however, remained virtually unchanged. This allowed us to determine how fatigue cracking and plastic deformation during fracture affect the local hardness and elasticity of the steel.

Keywords: steel gas pipelines, mechanical properties, hardness, instrumental indentation.

This article examines one possible approach to reducing the requirements for quantitative accuracy of shape deviations. To simplify the assessment of mating quality, it is proposed to consider the parameters of their surface sections as spatial random processes. When determining the discrepancy between geometric dimension deviations and specified values, it is proposed to evaluate not individual quantities, but rather the change in the characteristics of random processes describing the geometric parameters of an individual section. It is established that, with a statistical approach to ensuring the reliability of the assessment of the set of characteristics of a random process, the need for precision in the initial data can be reduced. Using cylindrical surfaces as an example, it is shown that, depending on the specific requirements for the mating, the profile can be standardized or estimated within the boundaries of the geometric tolerance – the arithmetic mean deviation of the profile relative to the nominal or actual diameter.

Keywords: geometric shape tolerance, mating quality assessment, surface structure, random processes, accuracy standardization, measurements.