International Scientific Journals
of Scientific Technical Union of Mechanical Engineering "Industry 4.0"

Due to the increasing complexity and cost of Engineering Structures, and consequently the growth of operating costs for maintaining the operational reliability of these structures, new approaches to monitoring their technical condition directly without decommissioning are required. Previously conducted studies have shown that the most effective method of such monitoring is non-destructive testing based on acoustic emission. This article presents the basic principles of organizing such monitoring during operation based on the “Technical Health Condition” (THC), “Structural Health Monitoring (SHM), Condition-based Monitoring (CBM)) or “Fail Safe Concept (FSC)”

Wood processing requires reliable automated inspection and classification of natural defects. Conventional vision methods are often inadequate for distinguishing visually similar defects, particularly bark and resin pockets. This study compares hyperspectral methods for wood-defect classification. Pine samples were imaged in the VNIR (400–1000 nm) and SWIR (1000–2500 nm) ranges. Images were manually labeled for earlywood, latewood, sound and black knots, resin and bark pockets, and pith. Classification workflows combined raw spectra, PCA, or wavelet-based dimensionality reduction with Pearson correlation, k-NN, and Random Forest classifiers. The results enable comparison of the suitability of individual spectral ranges, feature-reduction methods, and classifiers for automated defect identification

This study investigates the hydrodynamic and thermal characteristics of spark discharge during electric discharge treatment of Al–Ti powder mixtures in ethanol. Machine learning methods were applied to identify relationships between mixture composition, interelectrode gap, and discharge parameters. Among the tested algorithms, the Gradient Boosting model demonstrated the highest predictive accuracy for describing nonlinear plasma-dynamic processes.
The analysis revealed a linear increase in plasma channel pressure from approximately 270 to 450 MPa as the interelectrode gap increased from 5 to 35 mm, regardless of the Al–Ti ratio. In contrast, the pressure acting on the discharge chamber walls was strongly dependent on powder composition. Titanium-rich mixtures exhibited a decrease in wall pressure with increasing gap, whereas mixtures containing 80 wt.% Al showed the opposite trend.
The developed Gradient Boosting model demonstrated that thermal characteristics of the discharge are governed primarily by pulse and liquid parameters, while peripheral hydrodynamic effects are controlled by the composition of the powder mixture. The obtained results provide new insights into the optimization of electric discharge processing of metal powder systems.

In working process a certain part of energy transmitted by the fluid in every hydraulic system is transferred to the consumer, while the other part (because of hydraulic pressure loss) is transformed into heat. The temperature of the fluid is rising during the working cycle with power loss. Is the temperature of the hydraulic fluid is higher the physical characteristic of hydraulic fluids is changed. Some of this is viscosity, density, specific gravity, compressibility and modulus of elasticity and gas absorption. The experimental investigation of dynamic characteristics changes of a closed electrohydraulic power transmission system with the variation of hydraulic fluid temperature is presented in this paper. The experimental test stand was used for dynamic processes investigation in an electrohydraulic positioning system for different operating temperatures. The obtained step time responses are shown in few graphics.

This paper shows analysis of each regenerative heater’s influence on global steam power plant operating parameters. Analysis is performed for nine steam power plant versions (configurations) – from the Base power plant without regenerative heating system up to the Final plant which consists of eight regenerative heaters (one mixing and seven non-mixing regenerative heaters). According to the defined fluid operating parameters throughout the plant, it is obtained that each new regenerative heater added to the plant continuously reduces the mechanical power produced by the turbine, for 4.33 MW on average. Simultaneously, each added regenerative heater increases feedwater temperature at the steam generator inlet, which results in power plant cumulative fuel consumption continuous decrease (for 0.414 kg/s on average) to obtain the same steam outlet parameters. Considering plant overall efficiency, it must be highlighted that each regenerative heater added to the plant continuously increases plant overall efficiency from the Base plant until the Final plant, for 0.43% on average.

Titanium matrix composites reinforced with titanium borides (TiB) represent a promising class of advanced structural materials due to their high specific strength, hardness, wear resistance, and thermal stability. The combination of titanium alloys with ceramic TiB reinforcing phases enables the development of lightweight materials with improved mechanical and эксплуатаційними characteristics for aerospace, biomedical, and engineering applications.
This study investigates the fabrication of Ti/TiB titanium matrix composites using X-Beam 3D printing technology. The process is based on electron-beam additive manufacturing under vacuum conditions, which ensures stable melting conditions, reduced oxidation, and controlled heat input during layer-by-layer deposition. Special attention was focused on the in situ formation of TiB reinforcing phases and their influence on the microstructure evolution of the composite material.
Microstructural analysis was carried out using scanning electron microscopy and metallographic techniques. The obtained results demonstrated the formation of dense composite structures with relatively low porosity and homogeneous distribution of reinforcing phases within the titanium matrix. TiB particles and whisker-like precipitates were observed to form during solidification, contributing to microstructure refinement and strengthening effects.
The fabricated Ti/TiB composites exhibited improved structural uniformity and enhanced hardness compared with unreinforced titanium materials. The morphology and distribution of TiB phases were found to depend on the thermal conditions and processing parameters of X-Beam printing. The results confirm the potential of X-Beam additive manufacturing for producing advanced titanium matrix composites with tailored microstructure and improved performance characteristics.

In the present study, a combined approach for the synthesis of multicomponent coatings in the SiO₂–CaO–P₂O₅ system was developed using a sol-gel process combined with electrochemically assisted deposition. Tetraethylorthosilicate (TEOS), calcium nitrate (Ca(NO₃)₂) and citric acid (C₆H₈O₇·H₂O) were used as precursors. The obtained materials were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The formation of amorphous-crystalline structures characteristic of bioactive silicate-calciumphosphate systems was established. The combined approach demonstrates effective control over the structure formation processes and allows the preparation of multicomponent oxide coatings with potential for application in bioactive and functional surface systems

This work presents a combined experimental and simulation study of resist profile evolution in electron beam lithography (EBL) using poly(methyl methacrylate) (PMMA) resist. The influence of key process parameters, including exposure dose, electron beam energy, and resist thickness on the resist profile formation, sidewall shape, and feature fidelity is systematically investigated. Particular attention is given to proximity effects caused by forward and backscattered electrons, which lead to dose redistribution and profile distortions. Experimental results show a strong dependence of PMMA resist profiles on lithographic conditions, affecting sidewall angle and linewidth variation. Bilayer PMMA systems are also examined to evaluate improvements in profile control and undercut formation for lift-off processes. Simulation of resist development is employed to model resist profile evolution and predict structural changes under varying conditions. The comparison between experimental and simulated results demonstrates good agreement, confirming the validity
of the modeling approach. The study provides deeper insight into PMMA resist behavior and supports optimization of EBL process parameters for improved nanoscale patterning accuracy.

In the present study, multicomponent Zr–Ti–Sm–Nd–Al oxide coatings were successfully synthesized via the sol–gel method and deposited on glass substrates using the dip-coating technique. The preparation procedure involved the formation of stable precursor sols and oxides based on zirconium, titanium, samarium, neodymium, and aluminum compounds, followed by controlled hydrolysis, aging, multilayer deposition, and thermal treatment at 430 °C. The obtained coatings were investigated with respect to their structural, compositional, and optical properties using X-ray diffraction (XRD), energy-dispersive X-ray fluorescence spectroscopy (XRF), and UV–VIS–NIR spectroscopy. The experimental results demonstrated the successful formation of uniform and transparent oxide layers with thicknesses ranging from approximately 39 to 57 nm, depending on the number of deposited layers. XRD analysis revealed the presence of nanocrystalline monoclinic ZrO2 as the dominant crystalline phase, while no separate crystalline phases related to Ti, Sm, Nd, or Al oxides were detected, suggesting homogeneous incorporation of the dopants into the oxide matrix. Optical characterization showed high transmittance in the visible and near-infrared spectral regions, close to that of the untreated glass substrate, indicating the suitability of the coatings for optical and photovoltaic applications. The incorporation of rare-earth and aluminum-containing species contributes to improved structural stability and functional performance of the coatings. The obtained results confirm that the combined sol–gel and dip-coating approach is an effective route for the fabrication of multifunctional transparent oxide coatings with potential application as durable self-cleaning and protective layers for photovoltaic panels and related optical systems.

This work presents a study of applicability of optimal control theory to the design of a electrohydraulic power transmission. The system involve hydraulic cylinder, loaded with time-variable force and two-stage electrohydraulic servovalve, including elasticity of steal cylinder and tubing and compressibility of oil. An optimal control low has been formulated with performance index requiring maximum quickness and output power and minimum control energy. The obtained optimal low can be used for industrial optimal automatic controller. There are shown optimal dynamic processes for different initial conditions and loading force.

In this paper is performed exergy and isentropic analysis of a helium closed-cycle gas turbine plant and all its main components. In the real operating conditions, turbine produces mechanical power equal to 546.27 MW, turbocompressor consumes mechanical power of 268.74 MW and the useful mechanical power delivered for the electric generator drive is equal to 277.53 MW. The highest possible mechanical power which can theoretically be delivered for the electrical generator drive (ideal useful mechanical power) is equal to 351.89 MW. Helium gas turbine is the component in the observed plant which has the lowest exergy destruction (9.40 MW) and the highest exergy efficiency (98.31%) of all components. Precooler has the lowest exergy efficiency of all plant components, equal to 47.66% only. Due to the usage of cooling water, precooler exergy parameters are highly sensitive to the ambient temperature change. Whole analyzed plant has exergy destruction of 261.79 MW and exergy efficiency of 48.69%, what is in the same range as for the comparable closed-cycle gas turbine plants.

This paper examines an improved method for calculating the stiffness and strength of a pre-twisted wing for special-purpose aircraft. These wings represent a type of adaptive wing, the development of which is the subject of active research in many industrialized countries due to the pressing need for improved aerodynamic performance. Such wings are intended for use in experimental aircraft to determine the influence of their aerodynamic parameters over a wide range of angles of attack during twisting during takeoff, landing, and, most importantly, during cruising flight for complex missions. For example, during rescue operations in hard-to-reach areas or the use of military aircraft for special defense missions.
Such variable-geometry wings require comprehensive research using modern methods of strength of materials and elasticity theory. In this regard, the problem being solved is one of the main fundamental issues of structural mechanics of special-purpose aircraft.