This paper addresses the static strength assessment of bogie frames for PE2 (M, U) series industrial traction units used in the mining industry. Currently, a significant portion of the widely operated PE2M and PE2U traction units has been in service for 40-50 years. Given that the manufacturer-specified service life for these units is 24 years, there is a critical need to justify the feasibility of extending their operation to more than double their original design life. The objective of this research is to determine the mean stress of the bogie frame loading cycle. A 3D model of the bogie frame was developed using SolidWorks, and structural analysis was performed via the Finite Element Method (FEM) in Ansys Mechanical. The finite element analysis results indicated a mean Von Mises stress of 63 MPa, and a safety factor of 2.65. Based on the findings, relatively higher stresses were observed in the zones beneath the central pivot plate of the pivot transom. The low values of mean stress, combined with the biaxiality levels, confirm that the bogie frame possesses sufficient static strength. These research findings can be utilized to evaluate the fatigue strength and residual life of the bogie frame, as well as to justify its service life extension.
In order to alleviate the fatigue damage caused by resonance in the combined multi-layer linear vibrating screen, this study conducted modal and harmonic response analysis using Workbench finite element analysis software. The results showed that there was a resonance risk at the 9th natural frequency. By optimizing the thickness of the side plates (increasing it by 4 millimeters), the frequency was successfully removed from the working range. This paramete optimization significantly improved the dynamic performance and reliability of the structure, providing a solid theoretical basis for design.
This paper presents a minimum-cost flow model for optimizing road freight delivery in a mountainous transport network, using Kyrgyzstan as a representative case of a landlocked Central Asian economy. The proposed approach integrates transportation cost, handling cost, and time-delay penalties into a unified linear programming framework in order to evaluate both domestic and cross-border freight movements under capacity and delivery-time constraints. The freight system is represented as a directed transport graph whose nodes correspond to logistics hubs and demand points, while arcs describe road corridors with different operational characteristics. The model was implemented in Python using a linear programming solver and calibrated with recent transport statistics and corridor data. For the domestic scenario with a balanced freight demand of 500 tons, the optimized total logistics cost reached 18,750 USD, of which 68 % corresponded to transportation, 17 % to handling, and 15 % to delay-related costs. For the extended cross-border scenario with a total volume of 800 tons, the optimized cost increased to 32,400 USD, while delivery time rose to 36-42 hours due to border-related delays. The results demonstrate that, in mountainous freight systems, time-dependent factors substantially affect route efficiency and total logistics cost. The study shows that minimum-cost flow optimization can support engineering decision-making in freight transport planning, corridor modernization, and customs process improvement in Central Asia.
This study investigates the nonlinear bending behavior of circular thin reinforced concrete (RC) and steel-reinforced concrete (SRC) plates under short-term and long-term loading, with particular attention to the influence of support contour compliance. A calculation framework is developed for the stress-strain analysis of axisymmetrically loaded circular plates by accounting for geometric nonlinearity, material nonlinearity, reinforcement effects, and time-dependent deformation. Experimental studies were carried out on circular RC plate models interacting with a support ring, and the measured deflections were compared with theoretical predictions. The results show that the proposed model captures the main features of plate deformation, including the nonlinear increase in deflection with load and the redistribution of the stress-strain state near the contour. For the considered loading cases, the discrepancy between calculated and experimental deflections did not exceed 17 %, which confirms the engineering applicability of the developed approach. It is also shown that support contour compliance significantly affects the long-term behavior and load-bearing response of the plates. The obtained results can be used to improve the design and assessment of circular RC and SRC plates, especially in structures where nonlinear effects and contour deformability must be taken into account.
Slope stability in seismically active areas is a crucial issue in geotechnical design, as failure can have severe consequences for infrastructure and public safety. This study explores modern methods for calculating slope stability under seismic loads, including the limit equilibrium method (LEM), the finite element method (FEM), and the difference element method (DEM). Numerical modeling was conducted using the PLAXIS, GeoStudio, and Slide software packages. A parametric slope stability analysis was performed, considering various values of seismic acceleration, slope angle, and pore pressure. The stability factor calculated using the Bishop method (LEM) was compared with the results from FEM and DEM to assess the accuracy and limitations of each technique. The study revealed that the stability factor (FS) decreases as the slope angle and seismic acceleration increase. When the acceleration reaches 0.3 g, the stability factor falls below the critical value (FS < 1.0), indicating an increased likelihood of slope failure. Although FEM and DEM methods provide more accurate modeling of deformations and failure mechanisms, LEM, which is based on static equilibrium, may overestimate slope stability. This research highlights the effectiveness of numerical modeling in predicting slope stability under seismic loading. Future investigations are recommended to develop hybrid models that combine LEM, FEM, and DEM, apply machine learning methods for predictive stability analysis, and consider long-term factors such as soil erosion and cyclic seismic loads. The findings can be utilized to improve slope design safety and enhance the resilience of infrastructure in seismically active regions.
This study presents a semantic retrieval approach for Uzbek seismic safety regulations and engineering documents. The proposed system combines paragraph-level indexing with two retrieval models, a classical TF-IDF baseline and a FastText-based subword embedding model, to improve access to relevant regulatory and technical text units in a morphologically rich language environment. A specialized corpus was compiled from seismic engineering and safety documentation and segmented into paragraphs for fine-grained semantic search. The retrieval performance was evaluated on 100 domain-specific queries using Precision@5, Recall@5, Mean Average Precision (MAP), and Mean Reciprocal Rank (MRR). The experimental results show that the FastText model outperformed TF-IDF across all major metrics, achieving Precision@5 = 0.7444 and Recall@5 = 0.6875, compared with 0.6017 and 0.5418, respectively. The observed improvement was statistically significant according to paired t-test analysis ( t = 15.1372, p < 0.001). The findings indicate that subword-based semantic modeling improves retrieval quality for Uzbek seismic safety documentation and can support faster access to relevant engineering regulations and compliance information.
This paper investigates the dynamic stress concentration in two parallel underground cylindrical pipes filled with a compressible fluid and subjected to seismic excitation. The pipe-soil–fluid system is described as a coupled boundary-value problem within the plane dynamic theory of elasticity, in which each pipe is modelled as a thick-walled, homogeneous, isotropic, linearly elastic cylinder embedded in an infinite elastic medium and filled with an inviscid compressible fluid. The wave field around the two parallel cylinders is represented in bipolar cylindrical coordinates, and the displacement potentials are expanded in cylindrical wave functions of Bessel and Hankel type. Continuity of displacements and tractions at the outer pipe-soil interface, matching of normal velocity and pressure at the inner pipe–fluid interface, regularity at the pipe axis, and the Sommerfeld radiation condition in the surrounding medium are imposed simultaneously, leading to an infinite system of linear algebraic equations whose unknowns are obtained numerically. The model is first verified under harmonic P-, SV-, and SH-wave excitation; it is then extended to realistic seismic loading through an FFT-based transfer-function procedure, in which the harmonic solution serves as the frequency-domain Green operator. Numerical results show that the maximum dynamic stress concentration coefficient under the incident P-wave reaches 1.76 at d / D = 1.0; the limiting non-resonant distance between pipe centres increases from 5.0 m to 10.0 m as the incidence angle changes from 0° to 90°; and the presence of the internal fluid increases the seismic response by 10-20 %. Time-history analysis with the 1940 El Centro NS and 1966 Tashkent records confirms that these trends persist under realistic broadband ground motion. The novelty of the study lies in the simultaneous treatment of pipe–pipe interaction, internal fluid coupling, multiple incident wave types, and recorded seismic input within a single bipolar-coordinate analytical framework. The results are useful for the seismic design and resilience assessment of multi-line buried pipeline systems.
In this work using a mobile laboratory the operational condition of a road section (length: 47 km) of the “Ekaterinburg-Almaty” road located in the Kostanay region (northern Kazakhstan) was carried out. During the survey of the road section the main indicators as roughness, rut depth, total length of longitudinal and transverse cracks, areas of asphalt concrete pavement with a block cracking, elasticity modulus of the pavement structure have been evaluated. Intensity and composition of traffic is carried out by the MetroCount 5600.
In thermal power systems, coal-fired boilers contain dense flue gas with high-concentrations of particulate matter. Their acoustic attenuation characteristics directly determine the measurement accuracy of acoustic monitoring equipment. Systematic investigations on boundary layer attenuation caused by nonlinear acoustic effects under high-concentration conditions is still insufficient. This study establishes a two-dimensional numerical model of acoustic attenuation in particle-laden flue gas based on nonlinear acoustic theory and thermoviscous boundary layer mechanism. The influences of particle radius, volume fraction, particle distribution, and acoustic frequency on the attenuation coefficient are quantitatively analyzed under ambient temperature and atmospheric pressure. The simulation results in the particle-free medium are highly consistent with the Stokes-Kirchhoff theoretical solution. In particle-laden media, particle surface viscous dissipation is the main attenuation mechanism. The attenuation coefficient increases significantly with particle radius and volume fraction, increasing sharply below 1000 Hz and following the f 2 scaling law above 5000 Hz. The boundary layer overlapping effect under 1 % volume fraction further enhances energy dissipation. This model can improve the theoretical system of sound propagation in high-concentration suspensions, and provide a solid theoretical foundation for the design and optimization of acoustic monitoring devices in practical furnace environments.
This paper presents a modular lower-limb exoskeleton concept fo4r early rehabilitation after hip and knee endoprosthesis. The system combines a cable-driven (Bowden) mechanism, a Hip-Knee modular architecture, and an adaptive Assist-as-Needed control strategy. The “one motor – two functions” principle reduces system weight and improves energy efficiency. Real-time control based on IMU and force sensors ensures accurate and safe motion. The proposed solution provides a lightweight and adaptive approach for simultaneous rehabilitation of the hip and knee joints.
This paper presents an analytical solution for the axisymmetric flexure problem of a rotationally symmetric circular plate using the method of partial discretization of differential equations. The plate is considered under transverse loading and radial boundary action, which lead to a fourth-order differential equation describing the deflection of the plate. Since direct analytical integration of the governing equation may be difficult for non-uniform loading and boundary conditions, the partial discretization approach is applied to transform the original problem into a more convenient analytical-discrete form. Explicit expressions are obtained for the plate deflection, rotation angle, bending moments, and transverse shear force. The derived solution makes it possible to evaluate the influence of radial boundary load on the deformation behavior of the circular plate. Numerical examples and graphical results demonstrate that increasing the radial load leads to a systematic increase in deflection and internal force factors. The obtained results confirm the effectiveness of the proposed method and show its applicability for engineering analysis of circular plates and thin-walled structural elements subjected to axisymmetric loading.
The development of high-speed and heavy-haul railway traffic leads to an increase in dynamic stresses in rails, resulting in the formation of hidden fatigue cracks. Such defects are among the most dangerous because they cannot be detected by visual inspection and failure occurs suddenly without warning. In recent years, the primary direction of railway safety improvement has shifted from mere defect detection to quantitative assessment of defect severity and prediction of the rail residual life. This paper analyzes modern rail non-destructive testing (NDT) instruments, including ultrasonic, eddy current, magnetic, acoustic emission, and intelligent diagnostic systems. Their operating principles, sensitivity to various defect types, inspection depth, and fields of application are considered. Particular attention is given to phased array ultrasonic testing and high-speed inspection vehicles providing continuous in-motion monitoring of track condition. A methodology for quantitative assessment of hidden crack severity based on the fracture energy criterion and the stress intensity factor is proposed. A calculation model is developed to determine the probability of rail failure considering defect parameters, stress state, and traffic conditions. A calculation example for a standard R65 rail is presented. The results show that integrating multi-channel defectoscopy with mathematical residual life prediction reduces the probability of rail fracture by more than three times. The obtained relationships can be applied for transitioning from periodic inspections to a risk-based track maintenance system.
The intensification of earthwork operations is closely linked to the expanding use of continuous-action excavation systems, where rotary excavators play a key role. This study addresses the need for higher productivity in hard and frozen soils by introducing an innovative high-speed working body: a bottom-discharge inertial rotor using a “top-down” digging method. Experimental results for a 1540 mm diameter rotor at cutting speeds of 2-9 m/s in Category III-IV soils demonstrate that at a speed of 4.4 m/s, productivity reaches 256 m 3 /h. This is 4.5 times higher than that of traditional gravity-based rotors, while energy consumption is reduced by 15-40 %. By optimizing the rotor’s design, this technology ensures increased operational efficiency, improved soil transport, and a significant reduction in the machine’s overall weight. These findings provide a scalable engineering framework for developing next-generation, energy-efficient excavation machinery.
This study investigates the effect of calcium naphthenate obtained from alkaline waste of oil-refinery processes on the physical, mechanical, and rheological properties of BND 60/90 road bitumen. The proposed additive is considered as a waste-derived surfactant modifier aimed at improving the structural behavior and adhesion properties of bitumen used in road construction. Bitumen samples containing 5, 10, and 20 wt.% calcium naphthenate were prepared and tested in the temperature range of 40-140 °C using rotational viscometry. The results showed that calcium naphthenate affects the flow behavior of bitumen by increasing viscosity and promoting structure formation, especially at temperatures below 100 °C. The most effective modification range was found to be 5-10 wt.%, where improved adhesion to mineral materials and enhanced rheological stability were observed without excessive loss of penetration. The findings demonstrate that calcium naphthenate obtained from refinery alkaline waste can be used as a promising functional additive for bitumen modification and waste valorization.
This paper presents the development of a wearable system for human motion monitoring based on an inertial measurement unit (IMU). The proposed device enables real-time acquisition of angular velocity, linear acceleration, and orientation parameters of a body segment. An experimental prototype was implemented using an IMU sensor, Arduino Nano, and a data recording module. Laboratory tests focused on dorsiflexion and plantarflexion movements of the ankle joint. The results demonstrate that the system can accurately capture motion parameters and reflect changes in the Pitch angle corresponding to these movements. The proposed approach can be applied in motion analysis and rehabilitation monitoring. Future work includes integration of EMG and force sensors to extend the system functionality.
Novel Ti 1-x Fe x O 2 pigments ( x = 0-0.2) were successfully synthesized via the sol-gel method. Fe³⁺ doping preserved the rutile phase structure of TiO 2 while suppressing crystal growth; as the Fe content increased, the color of the pigments gradually transitioned from light red to deep red and further to reddish-brown. Among them, Ti 0.9 Fe 0. 1 O 2 calcined at 700 ℃ exhibited the optimal red hue ( a * = 25.7), while Ti 0.95 Fe 0. 0 5 O 2 treated at 800 ℃ demonstrated the best near-infrared reflectance performance (73.62 %). All samples showed notably higher reflectance in the NIR range compared to a commercial iron-oxide pigment of similar color (44.25 %). Furthermore, chromatic property tests after acid/alkali corrosion, together with thermogravimetric-differential scanning calorimetry analysis, confirmed the good chemical and thermal stability of this series of pigments. These energy-saving pigments show promising potential for application in high-efficiency energy-efficient building materials such as solar heat-reflective functional artificial stones.
The study presents a theoretical and experimental analysis of the variation in the fluidity of aluminum alloys – one of their key casting properties – under the influence of germanium and silicon. Based on experimental investigations, aluminum-based alloys were modified with different amounts of germanium and silicon, and the optimal modification level was determined through mathematical modeling. Initially, under laboratory conditions, aluminum casting alloys were alloyed with germanium at concentrations of 1 %, 2 %, and 3 % (relative to the charge), while 5 % silicon was added to each sample. The prepared melts were cast into standard spiral molds designed to evaluate fluidity. After solidification and removal from the molds, the lengths of the samples were measured, and a relationship between germanium content and fluidity was established in the form of a graph. Based on the obtained experimental data, the effect of germanium content on alloy fluidity was mathematically modeled. The modeling process was carried out using the Lagrange interpolation method. The resulting function allows for the theoretical prediction of the influence of varying germanium concentrations on the fluidity of the alloy.
This paper presents an experimental and analytical study of the erection state of large-span reinforced concrete shell structures for unique buildings. The research focuses on the stress-strain behavior of shell systems during installation, dismantling of temporary erection devices, and transition to the operational stage. Experimental modeling was carried out on large-scale models with scales of 1:10 and 1:4 for shells with spans of 48 m, 96 m, and more. Composite shells assembled from prefabricated and enlarged erection elements were investigated for different erection and dismantling sequences. The stress-strain state was evaluated under self-weight and installation loads, and the obtained results were compared with calculation data based on shell theory relations and engineering modeling procedures. It was established that the most rational dismantling sequence consists in first lowering the temporary posts and beams and then removing the forces in the temporary ties. This sequence reduces the forces in the ties by 21-34 % and ensures a more favorable stress state of the shell elements. For the studied shell configurations, labor costs were reduced by 26 %, while the weight of the erection equipment set was reduced by 2.4 times compared with traditional assembly methods. The discrepancy between experimental and calculated ultimate forces did not exceed 8.8 %. The proposed approach can be used in the design and construction practice of unique large-span buildings to improve erection safety, structural efficiency, and reliability.
The use of steel reinforcement in reinforced concrete elements negatively affects the long-term durability and reliability of structures due to its susceptibility to corrosion. At the same time, the relatively low elastic modulus of fiber reinforced polymer (FRP) reinforcement leads to increased deformation and deflection when applied independently in beams. Therefore, hybrid steel-FRP reinforcement provides an opportunity to compensate for the shortcomings of each material. However, computation methods for hybrid reinforced concrete beams are not presented in the current design codes. This article highlights the theoretical analysis of hybrid-reinforced beams and presents the obtained results, which are validated by experimental data obtained from tests on 27 beam specimens under four-point bending. The comparison between theoretical and experimental findings confirmed the accuracy of the proposed analytical model and demonstrated the enhanced strength and ductility of hybrid steel-GFRP reinforced concrete beams.
The dynamics of nonlinear viscoelastic plates and shells is a crucial area of study in modern mechanics, materials science, and engineering. This importance stems from the increasing demand for accurate modeling and analysis of structures subjected to complex loads, as well as the advancement of new materials and technologies. Modern materials, including carbon composites, polymers, and multilayer coatings, possess complex viscoelastic properties. Under dynamic loads, such as vibrations or impacts, viscoelastic materials exhibit time-dependent responses to these loads, necessitating careful consideration of their relaxation and creep characteristics. The unique viscoelastic properties allow these materials to adapt to applied loads, making them highly desirable for the design of sophisticated devices, such as sensors, membranes, and adaptive structures. Furthermore, interactions with external fields – such as electromagnetic or thermal forces – enhance the effects of nonlinearities and require the development of new modeling approaches. The paper presents the equations of dynamics of geometrically and physically nonlinear thin-walled elements. An operator approach based on Rabotnov’s hereditary kernels is proposed, which makes it possible to correctly account for relaxation processes. The novelty of the work lies in the consideration of the combined effect of geometric and physical nonlinearities. To demonstrate the applicability of the model, a numerical example of the deflection of a rectangular plate under uniform loading is examined. Graphs of the deflection evolution and the influence of thickness and relaxation parameters are presented.
