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The exploitation of deep resources and energy needs to break hard rock. Aiming at the problem of deep hard rock fragmentation, this paper proposes a variable cross-section squeezing pulsed water jet technology (SPWJ). SPWJ was generated under pump pressures of 5.2, 6.8, 8.5, 10, 11.9, and 13.8 MPa to carry out erosion experiments. Features such as rock spalling area, erosion depth, volume loss, and decomposition per unit inlet pressure are used to characterize the erosion performance of SPWJ. The results show that SPWJ can effectively crush granite under low input pressure. Granite crushing modes caused by SPWJ are mainly divided into three types: I: drilling type, II: erosion type, and III: cracking type. Compared with continuous water jet (CWJ), SPWJ has better overall erosion ability than CWJ when the erosion pressure is higher than 60 MPa, the dimensionless target distance is greater than 200, and the erosion time is less than 90 s. In addition, the erosion ability of SPWJ is better than that of CWJ under the condition of unit input pressure. The research results provide a reference for further optimizing the performance of SPWJ crushed granite in the future.

The simple single-stage reducer used in traditional electric vehicles is not enough to meet the requirements of electric vehicle for transmission efficiency， therefore， it is necessary to introduce two or more speeds transmission to electric vehicles to improve the efficiency of the whole power assembly. A new type of electric vehicle two-speed transmission is presented， which is composed of a wedge changing mechanism and a planetary gear system， and it can realize the efficient shift without power shock. In addition， the basic structure and working principle are introduced， and Lagrange method is applied to analyze the dynamics modeling of each component of the transmission， a two-degree of freedom Lagrange equation is established， the shift process model is built based on MATLAB/Simulink， the shift process is analyzed and the accuracy of the mathematical model is verified. It provides a certain basis for the study on dynamics modeling and shift quality optimization of the same type of transmission.

The computational model of spur gear meshing stiffness is established by using the hypothesis of cantilever beam of the gear. The meshing stiffness of spur gear is calculated by analytical method, and the distributional curve of meshing stiffness is obtained by comparison with FEM. Experimental verification of simulated results is performed by mechanical test-bed of closed flow. The experimental results show that the simulation results are in good agreement with the experimental results. Based on the FEM models of gear tooth with cracks of different lengths, the comparison between degradation trends in different meshing regions that shows that the degree of degradation in a single tooth meshing area is much higher than in a double teeth meshing region. In the FEM models of gear tooth with cracks of different lengths, the stiffness degradation rate of the double tooth indentation area increases first and then decreases, and the crack length is most obvious between 4 and 8 mm. [ABSTRACT FROM AUTHOR]

The loss caused by the failure of production equipment, especially power machinery equipment, has increased greatly, and the maintenance cost has also increased accordingly. When the low-speed and heavy-duty equipment fails, its fault signal generally shows the characteristics of non-stationary and non-periodic. The loss caused by the failure of production equipment, especially power machinery equipment, has increased greatly, and the maintenance cost has also increased accordingly. Some large-scale machinery has become the most basic equipment in modern large-scale production equipment. In the event of failure of these devices, local or even entire production lines will be discontinued. The earlier the fault is discovered, the more helpful the safe and reliable operation of the mechanical equipment. In order to ensure the normal production order, it is urgent to carry out research work on the micro-shock feature extraction of low-speed heavy-duty equipment failure. Based on the wavelet packet analysis method, this paper analyzes the types and characteristics of low-speed heavy-duty equipment faults. The fault signal data acquisition and analysis of low-speed heavy-duty equipment can realize the analysis of the time domain and frequency domain of the signal. Confocal laser scanning microscopy has been extended to the field of optical microscopy, including confocal fluorescence microscopy, confocal scanning fiber microscopy, color confocal laser microscopy, confocal grating optical microscopy and so on. It will soon become an important tool for semiconductor material testing and biomedical diagnosis. Scanning near field optical microscopy (SNOM) and surface plasmon resonance (SPR) are used to study the surface plasmon resonance (SPR) of gold films. A novel Kretschmann type surface plasmon resonance coupling device with unique structure was designed and built. Meanwhile, the preparation method of surface plasmon with thickness gradient was designed. [ABSTRACT FROM AUTHOR]