To date, composite materials, such as polymer concrete, have found wide application in various industries due to their unique properties combining high strength, resistance to aggressive media and durability. Improving the performance characteristics of polymer concrete is an important task aimed at expanding the areas of its application. One of the promising methods of increasing the strength of this material is the use of various fillers. In this paper, the effect of fillers, based on carbon and basalt fibres, on the mechanical properties of polymer concrete was investigated. The polymer concrete was made of the following components: rubble stone, sand, quartz flour and polyester resin. During the experimental work, the amount of carbon and basalt fibres in the polymer concrete mixture varied from 0 to 6%. Bending and compressive strength tests showed that the addition of carbon and basalt fibres increased these properties. The highest bending and compressive strengths were achieved when carbon fibre contents were up to 1.5%, while basalt fibres provided the highest strengths in the case of around 2%. These results confirmed that carbon fibres had a higher efficiency in strengthening polymer concrete compared to that of basalt fibres. This could be explained by the fact that carbon fibres had a higher tensile strength and modulus of elasticity, which allowed them to better redistribute loads within the composite material. The fibre length for carbon fibre, which gave the maximum increase in properties, was 10–15 mm. For basalt fibre, the maximum bending strength was reached at 20 mm and compressive strength at 10 mm. Increasing the content of carbon fibre above 2% and basalt fibre above 1.5% did not give further increase in mechanical properties. In conclusion, it could be stated that the use of carbon fibres as fillers offered significant advantages in strengthening polymer concrete, opening up opportunities for its use in more demanding conditions and in a wider range of industrial applications.

Purpose. The solution to one of the important problems of the underground mining method is to substantiate cost-effective, technologically feasible and safe variants for mining steeply dipping low-thickness ore bodies. Methods. Mining systems are substantiated on the basis of a detailed analysis of the developed and existing experiential variants for mining steeply dipping ore bodies, identifying production and economic disadvantages, as well as their causes. Findings.As a result of the research, the pillar raise performance in the mining system with ore shrinkage has been substantiated. The main parameters of the proposed variants for mining systems with ore shrinkage, intended for expansion-type supports and borehole breaking, have been substantiated. A design has been developed of fastening the material-running raises (MRR) and ventilating raises (VR) on the working and ventilation horizons to ensure their performance in the mining system with ore shrinkage. Originality. For the first time, dependences of dilution and labour productivity on the ore body thickness and the type of ore breaking for blast-hole stoping and borehole breaking for a single and “twinned block” have been obtained. In addition, a certain dependence of the loading and delivery performance on the average fractional composition, as well as on the delivery distance, has been obtained. Practical implications. The research is characterized by scientific innovations created for the first time, which are able to ensure the efficiency and safety of mining operations, while creating the ability to manage the loss of minerals and dilution in the block, as well as reaching their calculated optimal ratio in order to achieve the most cost-effective production rate.

This article considers the prospects of the application of building structures made of polymer concrete composites on the basis of strength analysis. The issues of application and structure of polymer-concrete mixtures are considered. Features of the stress-strain state of normal sections of polymer concrete beams are revealed. The dependence between the stresses and relative deformations of rubber polymer concretes and beams containing reinforcement frame and fiber reinforcement has been determined. The main direction of the study was the choice of ways to increase the strength characteristics of concrete with the addition of a polymer base and to increase the reliability of structures in general. The paper presents the results of experimental and mathematical studies of the stress-strain state and strength, as well as deflections of reinforced rubber-polymer beams. The peculiarities of fracture of reinforced rubber-polymer beams along their sections have been revealed according to the results of the experiment. The peculiarities of fracture formation of reinforced rubber-polymer beams have also been revealed. The conducted work has shown that the share of longitudinal reinforcement and the height of the fibrous reinforcement zone are the main factors. These reasons determine the characteristics of the strength of the beams and their resistance to destructive influences. The importance and scientific novelty of the work are the identified features of the stress-strain state of normal sections of rubber-concrete beams, namely, it has been established that the ultimate strength in axial compression and tension, deformations corresponding to the ultimate strength for rubber concrete exceed similar parameters for cement concrete 2.5–6.5 times. In the case of the addition of fiber reinforcement, this increase becomes, respectively, 3.0–7.5 times.

This work presents the results of a research study focused on the development and evaluation of an algorithmic optimal control framework for energy-efficient operation of screw compressors in smart power systems. The proposed approach is based on the Pontryagin maximum principle (PMP), which enables the synthesis of a mathematically grounded regulator that minimizes the total energy consumption of a nonlinear electromechanical system composed of a screw compressor and a variable-frequency induction motor. Unlike conventional PID controllers, the developed algorithm explicitly incorporates system constraints, nonlinear dynamics, and performance trade-offs into the control law, allowing for improved adaptability and energy-aware operation. Simulation results obtained using MATLAB/Simulink confirm that the PMP-based regulator outperforms classical PID solutions in both transient and steady-state regimes. Experimental tests conducted in accordance with standard energy consumption evaluation methods showed that the proposed PMP-based controller provides a reduction in specific energy consumption of up to 18% under dynamic load conditions compared to a well-tuned basic PID controller, while maintaining high control accuracy, faster settling, and complete suppression of overshoot under external disturbances. The control system demonstrates robustness to parametric uncertainty and load variability, maintaining a statistical pressure error below 0.2%. The regulator’s structure is compatible with real-time execution on industrial programmable logic controllers (PLCs), supporting integration into intelligent automation systems and smart grid infrastructures. The discrete-time PLC implementation of the regulator requires only 10³ arithmetic operations per cycle and less than 10² kB of RAM for state, buffers, and logging, making it suitable for mid-range industrial controllers under 2–10 ms task cycles. Fault-tolerance is ensured via range and rate-of-change checks, residual-based plausibility tests, and safe fallbacks (baseline PID or torque-limited speed hold) in case of sensor faults. Furthermore, the proposed approach lays the groundwork for hybrid extensions combining model-based control with AI-driven optimization and learning mechanisms, including reinforcement learning, surrogate modeling, and digital twins. These enhancements open pathways toward predictive, self-adaptive compressor control with embedded energy optimization. The research outcomes contribute to the broader field of algorithmic control in power electronics, offering a scalable and analytically justified alternative to heuristic and empirical tuning approaches commonly used in industry. The results highlight the potential of advanced control algorithms to enhance the efficiency, stability, and intelligence of energy-intensive components within the context of Industry 4.0 and sustainable energy systems.

The paper considers the possibility of reusing previously used railway rails. The analysis is conducted using the standards and operating conditions of the rails of one of the Central Asian states, Kazakhstan, as an example. The operation of these rails causes significant stresses, while the surface layers are strengthened as a result of cold hammering. These phenomena significantly change the physical and mechanical characteristics of rails. As a result, they may not be suitable in terms of parameters for basic use but can be suitable for installation on other tracks. The conducted studies have shown that when the standard service life of the RP65 rail expires, the surface layer is deformed to a depth of up to 300 microns, hardness increases, and internal residual stresses are formed. These changes lead to an increase in the strength properties of the rails. However, at the same time, cracks originate in the surface layer of the rail, thus worsening operational characteristics. The RP65 rails are used under a cyclic load of 700 kN (which is determined by the national standard), withstanding 790,000 cycles. When the load is reduced to 510 kN, these rails can withstand the 2,000,000 cycles required by the standard without failure. Thus, these rails can be reutilized only on non-loaded and non-critical sections.

Justification of rational parameters for manufacturing pump housings made of fibroconcrete