Microwave Power Transmission Based on Retro-reflective Beamforming

Microwave power transmission has the potential to supply wireless power to portable/mobile electronic devices over long distances (on the order of meters or even kilometers) efficiently. Nevertheless, several technical challenges remain to be resolved in order to accomplish practical microwave power transmission systems, including (i) minimizing power loss due to microwave propagation, (ii) preventing humans and other electrical systems from exposure to excessive microwave radiation, and (iii) reconfiguring wireless power transmission in reaction to environmental changes (such as physical movements of portable devices) in real time. In this chapter, a microwave power transmission scheme based on retro-reflective beamforming is proposed to address the above challenges. In the retro-reflective beamforming, wireless power transmission is guided by pilot signals. To be specific, one or more than one mobile device(s) broadcast pilot signals to their surroundings, and based on analyzing the pilot signals, a wireless power transmitter delivers focused power beam(s) onto the mobile device(s). Preliminary numerical and experimental results are presented to demonstrate the feasibility of the proposed retro-reflective beamforming scheme

Prevalence of allergic rhinitis among adults in urban and rural areas of China : a population-based cross-sectional survey

Purpose: The aim of the present study was to compare the prevalence of self-reported and confirmable allergic rhinitis (AR) with positive skin prick test (SPT) results among adults living in urban and rural areas of China. Methods: Adults from a community in Beijing and a village in Baoding were selected as representative urban and rural dwellers, respectively. All eligible residents were enrolled from the population register and received a face-to-face interview using modified validated questionnaires. Equal sets of randomly selected self-reporting AR-positive and AR-negative participants who responded to the questionnaires were also investigated using skin prick tests. Results: A total of 803 participants in the rural area and a total of 1,499 participants in the urban area completed the questionnaires, with response rates being 75.9% and 81.5% respectively. The prevalence of self-reported AR of the rural area (19.1%) was significantly higher than that of the urban area (13.5%). The elementary school of educational level increased the risk of having AR (adjusted OR=2.198, 95% CI=1.072-2.236). The positive SET rates among subjects with self-reported AR in the rural and urban areas were 32.5% and 53.3%, respectively; the confirmable AR prevalence of 6.2% and 7.2% among the rural and urban adults, respectively. Conclusions: The prevalence of confirmable AR is similar between rural and urban areas in China, although there is a higher prevalence of self-reported AR in the former

Design of intelligent power consumption optimization and visualization management platform for large buildings based on internet of things

The buildings provide a significant contribution to total energy consumption and CO2 emission. It has been estimated that the development of an intelligent power consumption monitor and control system will result in about 30% savings in energy consumption. This design innovatively integrates the advanced technologies such as the internet of things, the internet, intelligent buildings and intelligent electricity which can offer open, efficient, convenient energy consumption detection platform in demand side and visual management demonstration application platform in power enterprises side. The system was created to maximize the effective and efficient the use of energy resource. It was development around sensor networks and intelligent gateway and the monitoring center software. This will realize the highly integration and comprehensive application in energy and information to meet the needs with intelligent building