The article is devoted to the analysis of the main parameters (pressure, power, torque, and speed) of the electrohydrostatic drive of ground-based transport and technological complexes, which include roadbuilding equipment.
The authors develop a design algorithm and obtain dependencies characterized in the operation process of the specified drive type on the basis of a compiled method for calculating the basic parameters of hydraulic components that are part of an electrohydrostatic drive. These criteria include the drive’s ability to precisely process input signals; speed of rod travel at a specified load; total operating coefficient; unit power.
The purpose of this calculation method is to develop an efficient electrohydrostatic drive for road construction machines that combines the advantages of hydraulics (high power, tremendous force with small components and easy reversing) with the flexibility of electronics, which allows positioning of the working parts of these machines (bucket, arm, excavator boom, manipulator, grader or bulldozer blade and the rotation of road roller rollers) with an accuracy of millimeter in fractions for a second.
The combination of analytical and numerical methods allows designing a prototype (the digital model) of this drive with its main characteristics, and then simulate the entire system, studying the flows inside the pump and channels, as well as conducting thermal analysis to assess the heating of the liquid and the motor. An electrohydrostatic drive is a complex system that requires consideration of many factors. The article focuses on the optimal selection of hydraulic components (pumps, hydraulic motor), which are selected depending on the parameters of the electric motor of the drive.
The research is aimed at establishing a basis for further experimental methods, which are conducted to validate theoretical (analytical) data and develop methods for diagnosing and monitoring electrohydrostatic drive. Experimental methods are used to determine the rigidity of the drive, the removal of amplitudefrequency characteristics and the measurement of currents and pressures in various operating modes.

The aim of the research is to explore the potential for enhancing heat transfer and reducing hydraulic losses in piping systems by employing structured surfaces.
An evaluation of the thermal-hydraulic performance of rectangular riblets with a height of h = 1 mm and a height-to-width ratio of h/t = 1.1 is performed in comparison with a smooth surface and surfaces with equivalent sand-grain roughness (heights of 0.2; 0.3; 0.4; and 0.5 mm) under fully developed turbulent flow conditions at a Reynolds number of Re = 20 000. The authors conduct the research basing on CFD simulation results by the Ansys Fluent 19.1 R1 with periodic boundary conditions.
The results show that, unlike other surface types, the investigated surface with rectangular riblets demonstrates high thermal-hydraulic efficiency among all considered pipe surface forms (86 % higher compared to the smooth surface). Therefore, the research clearly demonstrates the high potential for the widespread application of riblets in thermal-hydraulic systems.

Analytical review provides a comprehensive and systematic examination of scientific literature and regulatory documents published over the past five years (2020–2025) addressing the critical issue of electromagnetic interference from overhead power lines on the corrosion reliability of buried main pipelines.
The paper categorizes and analyzes research across several key areas: the fundamental mechanisms of inductive coupling between alternating current sources and pipeline networks; the specific phenomena of alternating current induced corrosion and its distinction from direct current corrosion; the detrimental effects of induced alternating current voltages on the performance and effectiveness of cathodic protection systems; and the advancement of computational modeling techniques and risk assessment methodologies for predicting interference levels and corrosion likelihood. Key achievements in the field of negative impact standardization are identified, including the establishment of threshold alternating current density values for corrosion initiation and methods for its assessment. However, significant unresolved challenges persist, particularly the absence of universal, validated predictive models capable of accurately simulating complex field conditions involving heterogeneous soil structures, dynamic load variations from traction networks and high-voltage power lines, as well as the presence of coating defects and uneven deterioration of insulating coatings. Furthermore, the synergistic effects of combined alternating current and direct current interference over the long term remain insufficiently understood.
Based on the synthesized analysis, priority directions for future research are formulated, emphasizing the necessity for developing intelligent, adaptive protection systems that integrate real-time monitoring of critical parameters, employ probabilistic risk-based approaches for integrity management, and leverage digital twin technologies to enhance the operational safety and corrosion reliability of energy transportation infrastructure.

The paper considers the investigation of quartz sand as a filter material for water treatment systems of heat supply installations and to the development of quantitative criteria for forecasting its service life. The quartz sand filter is transformed into a composite material covered with aluminum and iron oxides, which are formed because of adsorption and deposition of ions from the source water during operation.
With the methods of electron microscopy and energy dispersion analysis it has been found that when a filter is operated on source water with an Al ≈ 0.58 mg/l and Fe ≈ 0.44 mg/l, there is a significant change in the microlattice surface of the sand particles with the development of the micropore. The authors established that the achievement of mass proportions of aluminum and iron in quartz sand of the 11.78 and 7.11 % order is an indicator of the maximum capacity of the filter adsorption and a justification for planning its replacement.
The proposed approach enables a transition from a calendar‑based maintenance schedule to a predictive management of the filter’s service life, prevents the exceedance of permissible concentration limits of contaminants in network water and the optimization of costs for water preparation.

The article is devoted to the study of the optimal use of a hybrid energy system, including solar and wind installations, a diesel generator, as well as a geothermal heat pump, to provide electricity and hot water to a medical center located in the city of Salmiya (Syria). This region is remote and is experiencing an acute shortage of electricity.
The system was modeled and optimized using HOMER PRO software. The calculations took into account a variable daily load of 60 kWh and a peak power consumption of 5.9 kW. Solar and wind sources provide the base load, while a diesel generator is used during periods of low generation. The geothermal heat pump provides hot water supply with high energy efficiency. The study analyzed the technical and economic efficiency of the proposed solution. The results show that using a hybrid system can significantly reduce operating costs and increase the reliability of energy supply in remote regions.

In the design vertical scroll compressors, engineers often need to calculate an oil pump that influences the compressor’s features, performance and reliability. The article presents the first research stage for developing the method for calculating such pumps: development of an experimental method for investigating the oil pump; comparison of the physical experiment using the developed method with known patterns; testing the influence of the angle of the inlet nozzle on the pump’s performance.
The authors analysed the publicly available materials and selected the structural elements that affect the pump or which effect needs to be checked. Moreover, the authors developed an experimental test bench and a method of conducting the experiment, which allowed considering the design features of the pump: the diameter of the channel; the diameter of the nozzle opening; the shape of the nozzle; the frequency of rotation of the shaft.
The error analysis reveals that the experiment's relative error is less than 3 %. Based on experimental data, the following dependencies are formulated according to the developed method: there is an inverse dependence of the pump pressure from the ratio of the hole radius at the pump outlet to the radius of the pump duct; there is a quadratic dependence of the pump pressure on the speed. These dependencies are consistent with the known data, which leads to a conclusion about the adequacy of the developed methodology and its applicability in further studies. Moreover, the authors also verify that the shape of the nozzle does not affect the pump’s performance. The results of the experiment presented in the article can be applied for verifying mathematical models of scroll compressors.

The article describes the procedure of the system assessment of air temperature of gas turbine compressors operating at linear stations of natural gas compression of gas pipelines in the southern regions of the Russian Federation.
Analysis of statistical data shows that the operation of a number of centrifugal superchargers in the summer does not meet the regulatory and technical requirements of the gas industry, leading to abnormal operation of power machines and equipment. Therefore, the authors propose to cool the air before it is supplied to the gas turbine engines in a special system of absorption refrigeration machines. This additionally expands the functionality of gas turbine units, providing deep air purification, reducing natural gas pressure loss, preventing the entry of various precipitation into the engine, and significantly reducing noise levels.
The article proposes and describes the operation of an original functional scheme that ensures efficient atmospheric air intake for the normal operation of gas turbine gas-pumping units during the summer season in the southern regions of the country. Moreover, the authors present new results of experimental studies of air cooling parameters in absorption refrigeration machines. The article also demonstrates a numerical example of analyzing the parameters of compressor stations with gas turbine units based on DG-90L2.1. The research also presents the dependence of the gas turbine engine power on the air temperature and the dependence of the gas compressor unit performance on the power.
The experimental results at the compressor station confirm the preliminary calculations of the efficiency of the new gas turbine unit with an air cooling system and prove the necessity of its installation.

The article discusses the structural features of low-consumption pump units of rocket and space modules: correction and detonation braking engines of spacecraft; pumps of auxiliary energy systems (supercharging, gas generation, systems for providing thermal regimes of aircraft, etc.).
The main features of such pumps are low working rates (V/ω < 5 ∙ 10^-7 м³); small dimensions of the flow path (< 0.1 m); low power (< 1 kW); high speed (up to 100 000 rpm). Open impellers are widely used in the design of impellers, which has determined significant difficulties in balancing power losses, considering the fact that the hydraulic and mechanical losses of the wheel do not have physical boundaries separating the relative movement in the flowing part of the impeller and the circumferential power losses in portable motion relative to the stationary wall of the pump housing. The traditional method of balance testing for closed wheels involves replacing the impeller with a “false” wheel with an identical boundary contour of cylindrical surfaces. In the case of open wheels, the authors propose a methodological technique for measuring the torque element by element on a fixed pump housing.
The constructive implementation of a special meter in a balancing suspension required significant costs in the development of methodological and computational support for testing. These modifications resulted in changes to the relations in the mathematical power balance model, as well as the calculation and simulation algorithms for the low-flow centrifugal pump.
As a result of testing, the resulting coefficient value for open-type impellers of the low-flow pump lies in the range of 0.8 to 0.9, which is slightly higher than the values for closed-type impellers.