No abstract

Table Tennis is a sport that everyone likes. But In today's treat time as gold, it is not easy to want to find a time to accompany a beginner; secondly, more and more the people want their table tennis technology higher, but they have no rivals. On this basis, in order to really make the table tennis training completely out of accompanying training, in this paper, the training machine and training system of table tennis have been studied.

Mechanical rotary table [ has been widely used in many work applications, where rotating capacity and power of the table are necessary elements to ensure the operation safety. The paper provides a rotary table design operated by hand movements to lift and fall, rotate and turn over in the absence of electricity and other external powers. Therefore, table should have a simple structure and be easy to maintain, meanwhile working area should be wide enough for convenient operation. Simultaneously good safety performance is of great significant in this design, which requires a reasonable arrangement of each components position to minimize the number of dangerous sections. The rotary part applies commonly used clamping flange, which allows the table to clamp different types of components. Mechanical rotary table can be applied in many different occasions, making it a truly multi-functional workbench.

The automobile crane is a crane which is arranged on a common chassis or special automobile chassis, the driving cab and a lifting control room. The advantages of this crane is good mobility, transfer quickly. weight body truck crane is a very important part, but also a key part of the whole balance, its main function is to balance the gravity center of the whole lifting, make more stable, more safety. The current general crane are fixed weight, the weight is directly arranged motionless in the car tail, installation or transportation unloading work. This design is mainly the counterweight body is designed into a movable and rotatable, this mechanism has good flexibility, can adjust the balance weight body position, equivalent to adjust the focus of the counterweight body, enhance the lifting capacity and safety.

Electric vehicles (EVs) are one of the most practical solutions to the energy issue and environmental pollution. In recent years, EVs have developed rapidly, but are still limited by charging problems. The emergence of photovoltaic charging stations can solve the environmental pollution and charging problems. The location of charging stations is critical in the life cycle of electric vehicles. In this paper, a multiple-criteria decision-making (MCDM) method based on Geographic Information Technology (GIS) for optimal site selection is proposed. First, based on literature reading and expert interviews, a site selection index system was identified, including four aspects with a total of ten sub-criteria. Secondly, a spatial database of relevant evaluation criteria was established using GIS, and preliminary analysis was conducted. Then, the fuzzy DEMATEL (Decision-Making Trial and Evaluation Laboratory method) is applied for assigning the criteria weights. Then, potential sites are ranked using the fuzzy MULTIMOORA (Multi-Objective Optimization on the basis of Ratio Analysis) method. Then, the model was validated by siting the electric vehicle PV charging stations in Qingdao, and eight stations were identified in the preliminary selection stage, and the most suitable locations were finally selected through the MCDM stage. Finally, the reliability and validity of the model were further verified by comparative analysis and dual sensitivity analysis.