Background: Nittaku 40+ and DHS D40+ are two different brands of new plastic balls, both of which are designated as official match balls and widely used in international events. Due to the change of material and diameter from traditional celluloid table tennis ball to new plastic ball, the hardness and elasticity of the new plastic ball also change accordingly. The purpose of this study is to analyze the difference of the dynamic elasticity between the two brands of new plastic ball, taking Nittaku 40+ ball and DHS D40+ ball as an example.Method: Self-made experiment was designed to generate different levels of initial speed of table tennis ball to test the dynamic elasticity characteristics of DHS D40+ and Nittaku 40+. A high-speed camera was used to collect the trajectory of ball falling and rebound after hitting the table during the experiment, and the Kinovea software was used to process the falling and rebound trajectory and calculate the average speed of falling and rebound process, then accordingly calculate the rebound speed decrement rate. Results: Results showed that the rebound speed and decrement rate of DHS D40+ and Nittaku 40+ both increased with the increase of falling speed, respectively. When falling at slow and medium speeds, there was no significant difference of dynamic elasticity between DHS D40+ and Nittaku 40+. When falling at high speed, there was a significant difference of dynamic elasticity between DHS D40+ and Nittaku 40+.Conclusion: Compared with the DHS D40+, the Nittaku 40+ has bigger hardness and brittleness, and the sphere structure is more uniform, featuring better dynamic elasticity stability and rebound height.
Nittaku 40 + and DHS D40 + are new material seamed plastic table tennis balls, both of which are designated as official match balls and widely used. Due to the change of material and diameter of the new seamed plastic ball, its hardness and elasticity also change accordingly. The purpose of this study is to analyze the difference of the stroke effect between the two types of new material seamed plastic table tennis balls, taking Nittaku 40 + ball and DHS D40 + ball as an example. Table tennis players (N = 18) were randomly selected from the China Table Tennis College (M age = 15.16 ± 2.41; M height = 1.59 ± 0.32 m; M weight = 45.72 ± 5.17 kg). Each participant was all righthand shake-hands grip. The high-speed camera was used to measure ball speed and spin speed. Data normality was tested by using the Kolmogorov-Smirnov test. An Independent-Samples T test was conducted to assess the difference of the stroke effect between two types of new material seamed plastic table tennis balls (Nittaku 40 + and DHS D40+). Results showed that there was a significant difference between the two types of new material seamed plastic table tennis ball in the ball speed and spin speed during the backhand backspin loop stroke (p = 0.041, p = 0.022, respectively), and the ball speed and spin speed of DHS D40 + were higher than that of Nittaku 40 + ball. Compared with the DHS D40 + ball, when hitting the Nittaku 40 + ball, players need to increase the swing distance and hit the ball with more strength to improve the ball speed and rotation speed.
Sports play an important role in daily life. Every year, thousands of people watch sports events on TV or on the Internet, in which football events attract more attention. The performance of a team may have a huge impact on its fan loyalty. Therefore, the purpose of this study was to explore whether the performance of a team will affect the loyalty of fans, and how to affect the loyalty of fans. Applying web crawler to collect spectators’ comments on the performance of the Chinese Men's National Football Team in the 2022 FIFA World Cup Qualification, word frequency analysis, semantic network analysis and emotional analysis on these comments, it was concluded that the factors that affect fan loyalty from high to low were: fan attitude loyalty factor, fan identity factor, fan behavior loyalty factor, fan satisfaction factor. It was believed that this study could provide a reference for managers to improve fan loyalty.
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