Journal of Mechatronics and Artificial Intelligence in Engineering
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Enhancing sound absorption of Helmholtz resonance metamaterials with extended microperforated neck
Get PDFTo enhance sound absorption of Helmholtz resonance metamaterials in low frequency region with simple structure and engineering practicability, according to the well-established acoustic absorption theory of micro-perforated panel, a novel designed Helmholtz resonance metamaterial with extended microperforated neck is proposed, and a theoretical modelling method is developed by using the transfer matrix method which is validated by finite element simulation. Both theoretical calculation and finite element simulation results show that sound absorption performance of proposed Helmholtz resonance metamaterial is improved significantly compared to that of Helmholtz resonator with normal neck, and the resonant absorption coefficient is close to 1. The influence of geometric parameters of microperforated neck is also investigated in detail, and some meaningful conclusions are drawn. This work provides a perfect solution for low-frequency noise control with Helmholtz resonance metamaterials
Improved APF-based path planning for aircraft towbarless towing vehicle system
Get PDFTo enhance the maneuvering efficiency and safety of the aircraft towbarless towing vehicle (TTV) system, this study presents an optimized path planning method based on an improved artificial potential field (APF) algorithm. First, comprehensive kinematic and dynamic models are established, incorporating both lateral and yaw motions of the TTV system. Second, to mitigate obstacle interference challenges in complex airport environments, the proposed method introduces an innovative relative-distance safety factor and implements a dual-repulsive-force cooperative planning strategy, effectively overcoming the traditional APF algorithm’s limitations regarding goal unreachability and local minima. Furthermore, the integration of Bézier curves ensures curvature continuity in the planned path, thereby maintaining compliance with kinematic constraints. Finally, a constrained-motion TTV simulation model is developed to validate the algorithm’s performance. Simulation results demonstrate that, in static obstacle scenarios, the proposed method successfully enables autonomous path planning, generating smooth and collision-free trajectories. This approach offers a robust solution for ensuring stable and reliable operation of the TTV system in real-world airport environments
Development of methodology for monitoring of metalworking fluids quality
Get PDFEfficient monitoring of metal-working fluids (MWFs) is crucial to maintaining optimal machining performance and ensuring the safety and health of workers in the metalworking industries. Knowledge of the performance of cutting fluids in the machining of various workpiece materials is very important to improve the efficiency of any machining process. Metal machining companies using MWS have the opportunity to choose the best product from the wide range offered, which can differ in physical parameters as it is designed to be best for the selected process. The unique adaptation to the manufacturing process poses certain challenges in monitoring MWS quality during machining. The importance of MWS quality is crucial, which can lead to costly defects and loss of workpieces. The monitoring only by the quality lab sometimes is insufficient. This article presents the development of a sensor for the indirect monitoring of MWFs, aiming to provide a cost-effective and nonintrusive solution to assess the quality and condition of these fluids. The measurement results are compared with those of other emulsion quality control protocols. Its implementation can significantly enhance the efficiency of MWF management, leading to improved machining performance, reduced downtime, and enhanced worker safety. The sensor's nonintrusive nature eliminates the need for frequent manual sampling, reducing costs and minimizing the environmental impact associated with traditional monitoring practices. Overall, the sensor described in this article offers a viable solution for indirect monitoring of MWFs, contributing to the advancement of smart manufacturing and the optimization of metalworking processes
Study on stability of shaft surrounding rock under adjacent shafts mining disturbance in underground mine
Get PDFThe stability of mine shafts is crucial for safe production in underground mining. To elucidate the impact of adjacent shaft mining disturbance on shaft structural stability in underground mines, this study takes a Manganese Mine in Guizhou, China as a case study. A refined three-dimensional model at engineering scale was established by using the Rhino-FLAC3D coupled modeling method. This model can numerically simulate the mining of ore bodies at different stages of mining. The displacement, stress distribution, and plastic zone in both strata and shaft surrounding rock were systematically analyzed to reveal the response laws of shaft surrounding rock under mining disturbance. The results showed that during the first and second mining phases, no measurable deformation occurred in the surrounding rock of the main shaft, auxiliary shaft, or ventilation shaft. During the third mining phase, the maximum displacement observed in these shafts’ surrounding rock reached 0.048 m, which remains within the stability threshold of rock masses according to evaluation criteria. Regression analysis was conducted on the monitoring displacement of three mining stages, and power function fitting curves were obtained. Plastic zones (20-30 m range) developed along the periphery of goaf areas, maintaining a safe distance of 45-55 m from adjacent shafts. A stress gradient formed around goaf areas, with tension stresses up to 1.33 MPa exceeding the ultimate tension strength of roof strata. There was potential tension failure in the roof strata of the goaf. Although mining disturbance effects on main and auxiliary shafts intensified with depth progression, no substantial structural impacts were observed. This confirms that all shaft structures can maintain stability during operational phases. The findings provide theoretical guidance for shaft stability control in deep mining operations
A cost model analysis in the process of refining petroleum using supplementary variable technique
Get PDFThis paper presents a cost model analysis for refining petroleum using an MX/G(a , b)/1.MX/G(a , b)/1 queuing system with two stages of heterogeneous services under steady-state conditions. The study derives the total average cost per unit time for two distinct service phases: Phase I and Phase II. In the first case, the analysis focuses on the total average cost of the system when the server operates in Phase I with a probability of π1 at any given time, and in Phase II with a probability of π2. Additionally, the model incorporates holding costs, operating costs, renovation costs for both phases, and closure time costs. Finally, numerical tables and graphical representations are provided to illustrate the observations regarding the total average cost, renovation rate, and arrival rate
Effect of vibration on the calculated resistance of sandy soils
Get PDFIn the territories of the Republic of Uzbekistan, where sandy soils are widespread, it is important to forecast and eliminate the consequences of possible accidents that may arise under the influence of oscillatory movements, taking into account engineering-geological and hydrogeological conditions, during the period of their use as a foundation for the construction of buildings and structures. Therefore, a number of scientists have studied and expressed their opinions on the change in resistance of sandy soils when exposed to vibration. One of the main objectives of the article was to determine the quantitative values of the design resistance R of sandy soils under the influence of vibration movements in natural conditions. To solve this problem, a DU-62 vibratory roller was used to vibrate sandy soils at a test site located in the Termez and Jarkurgan districts of the Surkhandarya region. Before and after the application of vibration using a vibratory roller, vibration behavior data were obtained using a UNI-T UT315A portable vibration meter and the measurement results were processed. As a result, it became clear that when designing buildings and structures in areas with widespread sandy soils, it is necessary to take into account that the calculated resistance of sand under the action of vibration forces decreases by 1.18 times compared to the absence of vibration movements. In this case, if the earthquake results in ground movement, then when designing buildings and structures, the calculated resistance of sandy soils should be increased by 1.18 times
The technology of non-stop passage of high-speed passenger and freight trains on double-track sections and its impact on operational performance
Get PDFCurrently, a mixed system of high-speed passenger and freight trains has been implemented on the railways of Uzbekistan. During the movement of high-speed passenger trains on double-track main line sections, the movement of freight trains at all stations and segments is temporarily suspended for a specific period. From this perspective, in the present time, the suspension of freight train traffic is leading to numerous technical and economic expenses. In this article, based on experimental runs using the technology of passing freight trains without stopping, train movement schedules have been drawn up, and train operations have been organized without unnecessary stops. This research paper provides a restructured overview of the introduction and practical implementation of non-stop train operation technology for double-track railway lines where both high-speed passenger and freight trains operate simultaneously. Using real operational schedules, comparative experimental charts were developed to evaluate the new approach. The outcomes of this analysis demonstrate how the proposed technology influences efficiency and key performance indicators of train movements. A regression-based analytical model was also constructed to determine the relation between freight train waiting time and average section speed, ensuring reliability through statistical verification. Furthermore, the application of innovative solutions and technologies mentioned in this article to sections of high-speed highways creates an opportunity to increase transport transit potential and improve economic indicators
Research on fault diagnosis of rolling bearings based on multi-method fusion
Get PDFTo address the limitation that Variational Mode Decomposition (VMD) relies on empirical settings for the mode decomposition number K and penalty factor α, this paper proposed the RIME-VMD-KNN method for bearing fault diagnosis. Specifically, the RIME algorithm was used to intelligently optimize K and α of VMD, breaking the reliance on experience; Pearson Correlation Coefficient (PCC) was adopted to screen Intrinsic Mode Functions (IMFs) with high fault correlation for signal reconstruction, preserving key features; and the sample entropy of the reconstructed signal was input into KNN for fault identification. Experiments show that the optimization performance of RIME is superior to that of GA, GWO and AOA; the generalization ability is verified by supplementary tests on the XJTU-SY dataset; KNN is simpler and more efficient than SVM, proving the rationality of its selection; the confusion matrix and multiple random cross-validation confirm stability; and computing time and resource data are provided to verify the feasibility of embedded deployment. This method improves the reliability and real-time performance of diagnosis and has engineering value
Study on the impact of wheel roundness defects on axle fatigue damage
Get PDFWith the continuous increase in the operating mileage of China’s high-speed railway network, wheel out-of-roundness has become increasingly common in electric multiple unit (EMU) vehicles. Wheel out-of-roundness directly increases the vibration level of the axle, affects various vehicle components, and in severe cases, may lead to fatigue fracture of the axle – a key load-bearing component – thereby causing major safety incidents. To investigate the influence of wheel out-of-roundness on axle dynamic stress and to evaluate the fatigue strength of the axle under such conditions, this study analyzes the effects of different wheel flat lengths, polygon orders and depths, as well as various operating speeds on the dynamic stress of EMU axles. Based on numerical simulation results, the fatigue damage of the axle under wheel out-of-round conditions and the impact of wheel polygonal wear over one development cycle are calculated. The findings show that within a single re-profiling cycle, wheel flats shorter than 50 mm have a negligible effect on axle fatigue damage. Furthermore, a reference limit for polygonal wear depth is proposed, providing theoretical guidance for wheel maintenance and safety assessment of EMU vehicles
Effect of Si addition on phase structure and wear resistance of CoCrFeMoNi alloy coatings
Get PDFCoCrFeMoNi high entropy alloy coating was prepared on Q235 substrate by plasma cladding method. The phase structure, morphology characteristics, element distribution, microhardness, and wear resistance for this alloy without and with Si doping were investigated by XRD, OM, SEM, EDS, microhardness tester, and friction-wear tester, respectively. The results show that CoCrFeMoNi alloy is composed of a single FCC phase, while Si-containing alloy is composed of FCC main phase and HCP phase. Both alloys have a typical dendritic structure. There is a layer of isotropic fine-grained region near the fusion line, and a columnar crystal region away from the fusion line. After adding Si element, the enrichment of Mo element in the interdendrite region and Co element in the dendrite region significantly decreased, which is related to the Si-containing alloy can provide a liquid environment with longer duration, lower viscosity, and greater fluidity. The change of Cr element enrichment from interdendrite region to dendrite region is the result of comprehensive competition of mixing enthalpy, atomic radius difference, electronegativity, density, and melt flowability between alloying elements. The friction coefficients of the two alloys show a rapid increase first and then gradually stabilize with the increase of time. After adding Si element, the hardness and wear resistance of the alloy are greatly improved, which is mainly related to the increase of the lattice distortion of FCC phase, the formation of high-strength HCP phase and the reduction of internal defects