Journal of Mechanical Engineering, Automation and Control Systems
Not a member yet
1200 research outputs found
Sort by
Prediction of wharf subsidence deformation degree based on deep learning technology
Get PDFThis paper presents an algorithm that combines a convolutional neural network (CNN) with a gated recurrent unit (GRU) to predict the wharf subsidence deformation. First, the digital elevation model (DEM) image features of the wharf area were extracted using the CNN, and then the patterns of change in wharf settlement were captured using the GRU. Moreover, the wharf in the Longtan Port area of Nanjing Port, located in Jiangsu Province, was analyzed. When the CNN comprised three convolutional layers and the activation function was set to sigmoid, the prediction performance of the proposed algorithm was the best. In both short-term and long-term scenarios, the CNN+GRU algorithm had better prediction performance than long short-term memory and GRU models
The effect of the quantity and length of fibers on the mechanical properties of fiber-reinforced concrete based on polypropylene fibers
Get PDFIn these studies, the effect of polypropylene fibers on the mechanical properties of concrete was studied, and special attention was paid to determining their optimal amount and acceptable length. The fibers were added to the concrete composition in amounts of 0.1-0.5 % and lengths of 10, 20, 30, 40, 50 mm and tested. According to the results of the study, the highest results were recorded at a fiber content of 0.2-0.3 % and lengths of 20-30 mm, and the compressive strength of concrete increased by up to 15.9 % compared to ordinary concrete. When adding fibers in excess (≥ 0.4 %) or with a length of 50 mm, a decrease in strength was observed. The results obtained showed that it is possible to increase the quality and improve the strength of concrete by selecting the optimal parameters of polypropylene fibers
Study on the effect of suspension system friction of heavy-haul freight vehicles on the operation performance
Get PDFDuring the operational life of heavy-haul freight vehicles, the long-term wear between components can affect the suspension parameters. Suspension system wear has a significant effect on the dynamic performance and wheel wear. Experimental tests are performed to measure the changes in suspension system parameters after wear. A dynamic model and wheel wear model of the heavy-haul freight vehicles were established to analyze their dynamics and wheel wear performance. The results showed that with the wear of the suspension system, the stiffness parameters further increase. The dynamic performance of the vehicle system deteriorates after suspension system wear, with a decrease in the critical speed and an increase in safety and ride indexes. The analysis also reveals that the wheel wear increases as the stiffness parameters increase after the suspension system wear. This paper provides a basis for maintaining heavy-haul freight vehicle suspension systems
Fuzzy dynamic self-tuning based linear active disturbance rejection control for PMSM speed control
No full textIn this paper, a novel control approach, namely fuzzy dynamic self-tuning-based linear active disturbance rejection control (FDS-LADRC), is proposed for the speed loop system of permanent magnet synchronous motors (PMSMs). Specifically, a control framework based on the linear active disturbance rejection control (LADRC) is presented. Fuzzy dynamic self-regulators are developed to enable simultaneous adaptive adjustments of both the controller and observer parameters. Additionally, the stability analysis is provided. A series of numerical simulations demonstrates that FDS-LADRC achieves superior adaptivity, transient performance, disturbance rejection capability, and anti-noise ability under various operating conditions. For instance, during no-load startup, compared with the traditional LADRC, nonlinear active disturbance rejection control (ADRC), a variant of FDS-LADRC named IT2FDS which utilizes interval type-2 fuzzy systems as fuzzy dynamic self-regulators, a state-of-the-art fractional-order ADRC with fuzzy self-tuning (FSFOADRC), and sliding mode control (SMC), FDS-LADRC reduces overshoot by 10.82 %, 13.55 %, 7.36 %, 5.53 %, and 3.94 %, respectively, and shortens settling time by 0.0132 s, 0.0076 s, 0.0139 s, 0.0009 s, and 0.0156 s, respectively. Finally, corresponding real-world experiments are conducted to validate the effectiveness and superiority of FDS-LADRC
Current research status on the occupational hazards of hand-transmitted vibration: a case study in China
Get PDFThe hazards arising from long-term hand-transmitted vibration operations can cause significant damage to the human body. As China is a populous country, understanding the current situation of vibration exposure among workers in various related fields in China holds significant reference value. To this end, this paper analyzes data from core journal literature in China from the 1980s to the present based on the keywords hand-arm vibration disease, hand-transmitted vibration, and occupational exposure. This paper provides an overview of the current status of hand-transmitted vibration hazards, including the distribution characteristics, hazards, and diagnostic methods of hand-arm vibration disease, as well as the deficiencies in these diagnostic methods. It also integrates data on the vibration intensity, frequency, and prevalence of vibration tools to analyze the relationship between the prevalence of hand-arm vibration disease and the vibration intensity and frequency of vibration tools. The results indicate that the vibration tools causing occupational hand-arm vibration disease are primarily found in the mining and manufacturing industries, with rock drilling jobs and positions being dominant in the mining industry and grinding jobs and positions being dominant in the manufacturing industry. The A(4) values of grinding tools, jobs, or positions are significantly higher than China’s limit value of 5 m/s2 for hand-transmitted vibration. The A(4) distribution of rock drilling tools is more concentrated, while the A(4) distribution of grinding tools is broader. The current diagnostic methods have poor specificity and sensitivity. There is insufficient awareness of the hazards of hand-transmitted vibration. There is no significant correlation between A(4) and the prevalence of vibration white finger (P>0.05), and A(4) alone is insufficient to reflect the extent of harm caused by hand-transmitted vibration operations to the human body. Both low-frequency and high-frequency vibrations may be harmful to the human body, and there may be a positive correlation between the fundamental frequency of vibration tools and the prevalence of disease (r>0,P<0.05)
LSGAN-Transformer life prediction method for rolling bearings under few samples
Get PDFAiming at the problem that it is difficult to obtain a large amount of data for bearings with complex working conditions, which leads to the inability to accurately predict their life, a rolling bearing life prediction method based on few samples, LSGAN-Transformer, is proposed. A dropout layer is added to the LSGAN generator to avoid the overfitting phenomenon that often occurs during few-sample training. The normalization of each layer in the traditional Transformer model is moved forward to the input of the decoder and encoder submodules before the residual network, forming a direct gradient path from input to output, avoiding the problem of excessive expected gradient near the output layer that often occurs in the traditional Transformer network. Verification on the PHM2012 dataset and the XJTY-SY dataset shows that the MAE and RMSE of the proposed method are greatly improved; compared with other common prediction models, the MAE and RMSE of the proposed method are improved by 30.61 % and 35.93 % respectively
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
Enhancing the strength of steel grade 45 guide rails for ball rolling using the chemical-thermal carbonitriding method
Get PDFThe enhancement of guide rail strength for ball rolling applications is crucial to improving the durability and operational efficiency of the manufacturing process. One effective method for achieving this is carbonitriding, a chemical-thermal treatment that forms a hardened surface layer by saturating the material with both carbon and nitrogen at relatively low temperatures. This study was aimed at improving the mechanical properties of the guide bar used to hold balls on the rolling axis in ball rolling mills by chemical-thermal strengthening-carbonitration. Specimens of mild and medium carbon steel were used as tests. The process consisted in immersing the specimens in a bath with molten salts at a temperature of 570 °C and holding for 1.5 hours. The samples were then cooled in oil and then cleaned with high-pressure water. The study showed that the melt of salts based on urea and potassium carbonate saturates the steel surface with nitrogen and carbon, forming a hardened layer. The depth of the hardened layer depends on the exposure time, but after one hour, the penetration of diffusing substances slows down. This is due to the saturation of the steel crystal lattice with alloying elements (carbon and nitrogen) during carbonitration. The maximum hardening depth for high-alloy tool steels is 0.05-0.12 mm, for carbon steels 0.1-0.6 mm. Carbonitration can be used to increase the hardness, strength, wear resistance of balls without increasing the brittleness of the part
Design of a multifunctional UAV based on composite materials: integration of vacuum infusion, CFD analysis, and intelligent energy management
Get PDFThis study proposes an integrated design approach for a multifunctional UAV using composite materials, combining vacuum infusion, CFD-based aerodynamic analysis, and an STM32-based energy management system. CFD results showed a lift coefficient CL= 0.812, drag coefficient CD= 0.055, and L/D= 14.7, representing a 28 % improvement over aluminum structures. FEM analysis indicated a maximum stress of 312.4 MPa with a safety factor of 1.12, while vacuum infusion achieved 98.7 % resin impregnation, enhancing stiffness by 28 % and reducing weight by 25 %. The automated energy management system increased energy efficiency by 16.3 %, extending flight duration and improving operational stability
Study on the compaction and dynamic properties of loess enhanced by waste tyre rubber particles
Get PDFThis study investigates the compaction and dynamic properties of rubber particle-loess from Inner Mongolia through laboratory tests, including compaction tests and dynamic triaxial tests. Four rubber particle sizes (10 mesh, 20 mesh, 40 mesh, and 100 mesh) and four contents (5 %, 10 %, 15 %, and 20 % by volume) were tested under varying conditions: confining pressures of 50 kPa, 100 kPa, and 200 kPa, and freeze-thaw cycles of 0, 1, 3, 6, and 9. The tests aimed to simulate environmental conditions relevant to infrastructure in Inner Mongolia's loess regions. Results revel that adding 5 % 40-mesh rubber particles maximized dynamic shear modulus, damping ratio, and compactness. The dynamic shear modulus exhibited strain-softening behavior, which decreased with increasing dynamic strain, rubber content, and freeze-thaw cycles, but increased with confining pressure. The damping ratio showed a non-linear relationship with moisture content, showing a minimum at optimum moisture and increasing with freeze-thaw cycles while decreasing with confining pressure. Notably, the damping ratio of rubber particle-loess consistently exceeded that of plain soil. These results highlight the potential of waste tire rubber particles as an eco-friendly material to enhance loess engineering properties, particularly in cold regions with significant freeze-thaw effects. The study provides a theoretical basis for improving loess stability and seismic performance in geotechnical applications