普通高校体育课计算机辅助教学的实践研究

随着校园网建设的初具规模和计算机辅助教学技术(CAI)的不断发展,应用此技术开发的视频点播技术(VOD-Video on Demand)逐渐成为关注的热点,同时也为我们实施计算机辅助教学注入了新的活力。当前,无论是VOD还是CAI都存在着无法与体育实践教学同步使用的问题,本文运用文献资料法、问卷调查法、教学实验法及数理统计法等研究方法对普通高校体育选项课CAI课件的研制与应用进行了实践研究。通过实验得出结论:借助多媒体教室、多媒体电脑、数字投影机以及触摸屏电脑等技术设备,可以发挥网络多媒体技术和触控技术的优势,有效开发计算机辅助教学平台,逐步满足体育场馆内计算机辅助同步教学的需要,进一步丰富和改善体育场馆现代化教学手段,不仅能为学生体育课自主学习与合作学习提供良好的现代教育技术环境,而且为教师授课提供了更为广泛的教学信息资源。

Optimal Design of Transmission Characteristics for Hexagonal Coil Wireless Power Transfer System Based on Genetic Algorithm

Effective optimization methods are used to guide the optimal design of coil parameters,which is significant for improving the transmission performance of the wireless power transfer(WPT)system.Traditional methods mostly rely on the exhaustive attack method and finite element analysis(FEA)to achieve the coil parameter design,which have the disadvantages of complex modeling and time-consumption.To overcome these limitations,this study proposes an optimization strategy based on the genetic algorithm(GA),which considers the actual requirements of the efficiency and power of the WPT system.First,a direct integration method is proposed to simplify the analytical solution process of the mutual inductance between the hexagonal coils.Based on the mutual inductance model,the transmission characteristics of the hexagonal coil WPT system are deeply analyzed by the control variable method.Most importantly,with the proposed optimization objective function and its constraints,the GA is used to automatically achieve multi-parameter optimization of the hexagonal coil.Finally,a 500 W WPT system experimental platform is established,and the experimental results verify the feasibility of the proposed optimization method.

Solid-state transformer-based new traction drive system and control

A new type of traction drive system consisting of solid-state traction transformer （SSTT）, inverter unit, auxiliary inverter, traction motor and other key components is built in order to suit the demand of developing the next-generation electric traction system which will be efficient and lightweight, with high power density. For the purpose of reducing system volume and weight and improving efficiency and grid-side power quality, an efficient SSTT optimized topology combining highvoltage cascaded rectifiers with high-power high-frequency LLC resonant converter is proposed. On this basis, an integrated control strategy built upon synchronous rotating reference frame is presented to achieve unified control over fundamental active, reactive and harmonic components. The cartier-interleaving phase shift modulation strategy is proposed to improve the harmonic performance of cascaded rectifiers. In view of the secondary pulsating existing in a single-phase system, the mathematical model of secondary power transfer is built, and the mechanism of pulsating voltage resulting in beat frequency of LLC resonant converter is revealed, so as to design optimum matching of system parameters. Simulation and experimental results have verified that the traction system and control scheme mentioned in this paper are reasonable and superior and that they meet the future application requirements for rail transit.