Guangjun Wen

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Comparison of the Homegardens of Eight Cultural Groups in Jinping County, Southwest China. Species growing in 124 homegardens in 15 villages inhabited by 8 cultural groups living in Jinping County, southwest China, were recorded, together with information on the uses of the species and other features of the gardens. Data were gathered using key informant(More)
Tag collision severely affects the performance of radio-frequency identification (RFID) systems. Most anti-collision algorithms focus on preventing or reducing collisions but waste lots of idle slots. In this letter, we propose a time efficient anti-collision algorithm based on a query tree scheme. Specifically, the dual prefixes matching method is(More)
With the presentation of more reliable groupcast proposal for IEEE802.11 WLAN, the QoS of video transmission based on groupcast (multicast / broadcast) is improved. To adapt the network load and bandwidth dynamic change in WLAN environment, we design a flexible optimization mechanism that integrates video steam priority character with more reliable(More)
High-quality frequency references are the cornerstones in position, navigation and timing applications of both scientific and commercial domains. Optomechanical oscillators, with direct coupling to continuous-wave light and non-material-limited f × Q product, are long regarded as a potential platform for frequency reference in radio-frequency-photonic(More)
As broad deployed of wireless sensor networks, privacy concerns have emerged as the main obstacle to success. When wireless sensor networks are used in everyday life, the privacy about monitored object' sensitive data becomes an important issue. Consequently, providing efficient data aggregation privacy protection is desirable. However, the existing(More)
Effects of Commercial Harvesting on Population Characteristics and Rhizome Yield of Anemone altaica. Commercial harvesting constitutes a direct threat to numerous non–timber forest products (NTFPs), but its ecological effects have not been well documented. Anemone altaica Fisch. ex C. A. Mey, a spring ephemeral plant found in temperate forests of Eurasia,(More)
As wide applications of wireless sensor networks, privacy concerns have emerged as the main obstacle to success. When wireless sensor networks are used to monitor sensitive objects, the privacy about monitored object' locations becomes an important issue. When a sensor node reports a monitored object to base station by sending a series of packets through(More)
With the growth of multimedia services in today's IEEE 802.11 WLAN, the new standard IEEE 802.11e is presented to support QoS in WLAN. A concept called transmission opportunity (TXOP) has been proposed in 802.11e to limit the maximum time duration (named TXOPlimit) that a station can be allowed to retain the channel after winning a contention or receiving a(More)
Tag collision problem is considered as one of the critical issues in RFID system. To further improve the identification efficiency of UHF RFID system, a frame breaking policy is proposed with dynamic framed slotted aloha algorithm. Specifically, the reader makes effective use of idle, successful and collision statistics during the early observation phase to(More)
Metamaterials attain their behavior due to resonant interactions among their subwavelength components and thus show specific designer features only in a very narrow frequency band. There is no simple way to dynamically increase the operating bandwidth of a narrowband metamaterial, but it may be possible to change its central frequency, shifting the spectral(More)