The development of new technologies has undoubtedly promoted the advances of modern education, among which Virtual Reality (VR) technologies have made the education more visually accessible for students. However, classroom education has been the focus of VR applications whereas not much research has been done in promoting sports education using VR technologies. In this paper, an immersive VR system is designed and implemented to create a more intuitive and visual way of teaching tennis. A scalable system architecture is proposed in addition to the hardware setup layout, which can be used for various immersive interactive applications such as architecture walkthroughs, military training simulations, other sports game simulations, interactive theaters, and telepresent exhibitions. Realistic interaction experience is achieved through accurate and robust hybrid tracking technology, while the virtual human opponent is animated in real time using shader-based skin deformation. Potential future extensions are also discussed to improve the teaching/learning experience.

In order to efficiently drive a low-power DC motor using microwave power transfer (MPT), a compact power-receiving device is developed, which consists of a rectenna array and an improved DC-DC converter with constant input resistance characteristics. Since the conversion efficiency of the rectenna is strongly affected by the output load, it is difficult to efficiently drive a dynamic load resistance device such as DC motor. Using both continuous-wave (CW) and pulsed-wave MPT, experiments are carried out on driving the DC motor whose load resistance is varying from 36 to 140 Ω. In the CW case, the measured overall efficiency of the power-receiving device is constant over 50% for the power density of 0.25 to 2.08 mW/cm2. In particular, the overall efficiency is 62%, 70.8% for the power density of 0.25, 0.98 mW/cm2 where the received power of the single antenna is 13, 50 mW, respectively. In the pulsed-wave case, the measured overall efficiency is over 44% for a duty ratio of 0.2 to 1 for the power density of 0.98 mW/cm2.

This paper proposes a rate adaptation scheme (RAS) for a wireless local area network (WLAN) station powered with microwave power transmission (MPT). A WLAN station attempting to transmit data frames when exposed to microwave radiation for MPT, experiences a reduction in the physical (PHY) layer data rate because frames are lost even when the carrier sense mechanism is used. The key idea of the proposed scheme is to utilize the output of the rectenna used for receiving microwave power. Using rectenna output, a WLAN station based on the proposed scheme assesses whether the station is exposed to microwave radiation for MPT. Then, using historical data corresponding to the assessment result, the station selects an appropriate PHY data rate. The historical data are obtained from previous transmission results, e.g., historical data pertaining to the data frame loss ratio. The proposed scheme was implemented and verified through an experiment. Experimental results showed that the proposed scheme prevents the reduction in the PHY data rate, which is caused by the use of historical data stored in a single memory. Thus, the proposed scheme leads to an improvement in the WLAN throughput.

Based on filtering ground clutter power directly in the frequency domain, a new non-coefficient Adaptive MTI (AMTI) scheme is presented in this letter. The results of simulation example show that this scheme has smaller signal-to-noise ratio loss than the classical AMTI based on spectral estimation, as well as high improvement factor.