On the basis of the principal components analysis-particle swarm optimization-least squares support vector machine (PCA-PSO-LSSVM) algorithm, a fault diagnosis system is proposed for the compressor system. The relationship between the working principle of a compressor system, the fault phenomenon, and the root cause is analyzed. A fault diagnosis model is established based on the LSSVM optimized using PSO, the compressor fault diagnosis test experimental platform is used to obtain the fault signal of various fault occurrence states, and the PCA algorithm is employed to extract the characteristic data in the fault signal as input to the fault diagnosis model. The back-propagation neural network, the LSSVM algorithm, and the PSO-LSSVM algorithm are analyzed and compared with the proposed fault diagnosis model. Results show that the PCA-PSO-LSSVM fault diagnosis model has a maximum fault recognition efficiency that is 10.4% higher than the other three models, the test sample classification time is reduced by 0.025 s, the PCA algorithm can effectively reduce the input dimension, and the PSO-LSSVM fault diagnosis model based on the PCA algorithm for extracting features has a high recognition rate and accuracy. Therefore, the proposed fault diagnosis system can effectively identify the compressor fault and improve the efficiency of the compressor.

This work reports a single-electrode mode triboelectric nanogenerator (G-TENG) based on natural leaf as the friction layer for application in the field of outdoor self-power supply.

This paper aims to eliminate nonlinear friction from the performance of the digital hydraulic cylinder to enable it to have good adaptive ability. First, a mathematical model of a digital hydraulic cylinder based on the LuGre friction model was established, and then a dual‐observer structure was designed to estimate the unobservable state variables in the friction model. The Lyapunov method is used to prove the global asymptotic stability of the closed‐loop system using the adaptive friction compensation method. Finally, Simulink is used to simulate the system performance. The simulation results indicate that the addition of adaptive friction compensation control can effectively reduce system static error, suppress system limit loop oscillation, “position decapitation,” “speed dead zone,” and low‐speed creep phenomena, and improve the overall performance of the digital hydraulic cylinder. The control method has practical application value for improving the performance index of the digital hydraulic cylinder.

The advanced hydraulic support group combined with bolts (cables) constitutes the advanced coupling support system, which can ensure the stability of coal mine roadway safely and effectively. To explore the influence of the initial bearing capacity of the advanced hydraulic support on roadway roof deformation under anchor bar (cable) action. According to the actual geological conditions and roadway support of the 15106 working faces in Pingshuo Coal Mine, Yangquan, and Shanxi. Based on the change in the stress and displacement of the half‐space body under normal force in elastic theory and combined with the linear superposition principle, the contact mechanics model of the advanced hydraulic support group and roadway roof under anchorage is established. Selecting the measured anchor bar (cable) preload in the coal mine as the input load of the model, the stress and displacement distribution of the roadway roof under different initial bearing capacities are calculated. The calculation results show that the stress and displacement of the roadway roof along the axis exhibit a “symmetrical distribution” and the whole roadway exhibits a “saddle surface” gradient distribution during the active support of advanced hydraulic support under anchorage. The increase in the initial bearing capacity of the advanced hydraulic support has a great influence on the support effect in the middle area of the roadway and has a relatively small influence on the support effect in the surrounding area of the roof. With an increase in an initial support capacity, the stress gradient changes violently but substantially less than it would under the crushing strength of the surrounding rock. Using the similar simulation experiment theory, a similar simulation experiment roadway was established at 1:40, and the simulation experiment of an advanced hydraulic support coupling active support under anchor protection was carried out. The maximum error percentage of the theoretical calculation and experimental results of roof deformation under different initial bearing capacities is 19.51%, and the maximum error percentage of stress is 13.77%. The accuracy of the distribution law of roof stress and displacement under the initial bearing capacity in the process of active support obtained by theoretical calculation is verified. The research results provide a theoretical basis for advanced coupling adaptive support and the control of fully mechanized mining faces.

A model for virtual simulation analysis of the rigid‐flexible coupling of a shearer has been developed with the objective of addressing problems associated with lifetime mismatch and low reliability of pin rows of a scraper conveyor and the corresponding support mechanism of a shearer. Simulations were performed using the experimental roller load as stimulus. Results of the analysis demonstrate that the vertical cutting force on the roller serves to reduce the load on the plane support plates during shearer cutting, and the force on the right plane support plate is considerably smaller compared to that on the left plane support plate along the direction of motion of the shearer. Owing to action of the roller‐traction load, loads acting on the two guiding support plates increase significantly along the direction of shearer motion. Mechanical characteristics of the support mechanism were determined through experiments, and the accuracy of the virtual simulation model was verified. Simultaneously, mechanical characteristics of the shearer support mechanism were studied under varying pitch and roll angles. This study was performed to provide a base for analyzing the mechanical characteristics as well as optimizing the structural design of the shearer. Through fatigue‐life analysis of the support plate and subsequent optimization of the support plate structure, the life of the guide support plate was found to have been extended by approximately 1.5 times.

The gesture recognition technology based on flexible strain sensors has attracted widespread research interest in fields such as human-computer interaction. However, the complex fabrication process of current flexible strain sensors limits their mass production capacity. Herein, we introduce a fabrication method for strain sensor based on 3D printing technology. A custom serpentine-shaped flexible strain substrate was constructed using low-cost thermoplastic polyurethane elastomer (TPU) as printing material, which met the needs of mass production of flexible substrate and improvement of mechanical properties of sensor. Soaking the substrate in a specific proportion of N, N-dimethylformamide (DMF)/carbon black (CB) solution, the sensing layer based on stable conductive network was constructed on its surface using ultrasound technology, and further softening enhanced its deformation ability. The proposed strain sensor exhibits excellent sensing performance with the wide strain range of up to 200%, high sensitivity of 58.08, fast response time of about 0.1 s, and high durability (1000 cycles under 50% strain), achieving detection of human joint motion status. Finally, A wearable gesture recognition system was established based on the data glove integrated with flexible sensors and Support Vector Machine (SVM), achieving an accuracy rate of 96% for recognizing ten commonly used gestures and translating them into audible speech in real-time. The experimental results demonstrate the practical value and potential application of the designed sensor in wearable devices, and to build communication channels for people with language disorders in the future.