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1.
在射频识别系统中,存在阅读器与多个标签同时通信的碰撞问题,多标签识别的防碰撞算法是解决数据冲突的关键。本文分析了RFID多标签防碰撞原理,在此基础上提出了一些提高RFID多标签防碰撞效率的解决方法。 相似文献
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在射频识别(Radiofrequency Identification)系统的应用过程中,有一个关键的问题,就是当多个标签同时出现在识别区域时,如何无遗漏的读取各个标签的信息而不产生读取碰撞。本文基于动态树形技术对RFID防碰撞算法进行了研究。结果表明,该方法能够较好地解决标签读取碰撞问题。 相似文献
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无线门卫汽车身份识别系统采用有源RFID技术,实现快速准确的汽车身份识别。同其它RFID系统一样,本系统的实现重点也在于RFID防碰撞算法的实现。在此首先简单介绍了几种通信系统中常用的防碰撞算法,然后根据RFID系统的特殊性,总结了RFID系统经常使用的防碰撞算法的实现方法,最后提出了本系统防碰撞算法的实现过程。 相似文献
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射频识别技术具有非接触、双向数据传输的通信特点,在物流、交通及人员管理等领域中具有越来越广泛的应用。利用其进行城市道路中的车辆识别,可实现虚假车牌查找,车流量测量控制,超速违章行为查处等多种目的。但其难点在于城市道路中车辆识别涉及多目标识别和车辆移动速度快速等特点。现有射频技术已能实现移动速度高达25～40KM/h的标签识别。本文主要研究一种涉及以一定速度连续通过阅读器阅读范围内的多标签,发生碰撞时的防碰撞算法研究。以城市道路车辆识别为例,进行阐述。利用待识别物体与识别单元距离不同这一物理条件对待识别物体进行分组,依据空间位置的不同分为几组,加以相应的时延,降低发生碰撞概率,提高车辆识别效率。 相似文献
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超高频读写器的便携式设计是射频识别（RFID）系统广泛应用的关键.为实现超高频RFID读写器的便携式设计,提出一种超高频RFID读写器的设计方案.硬件系统主要包括读写器的射频前端、功率放大器、功率检测、天线阻抗调谐电路等,在设计过程中考虑信道指标并对其进行评估;在对ISO/IEC18000-6的三种协议标准进行比较的基础上选用ISO/IEC 18000-6C协议,设计相应软件系统主要包括基带模块及防冲突碰撞模块.对硬件进行评估计算并结合硬件对软件进行验证及测试,结论如下：该读写器具有功率消耗低、体积小、接口丰富等便携式优点;硬件系统性能稳定;软件功能运行良好.上述设计有效实现了射频识别系统的便携式设计. 相似文献
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《科技通报》2015,(8)
通过设计计量器具物资标签批量读取算法,提高对大型物流物资的收发和计量效率。传统算法采用中间件技术实现对计量器具物资标签批量读取,当标签容错编码不稳定时,标签的批量读取效率不高。提出一种基于RFID的计量器具物资标签批量读取算法。首先对标签批量读取数据的层次化融合,然后在加量器具终端实现对数据的整合,在标签批量读取过程中,采用超高频射频识别技术(UHF RFID),得到标签数据的搜索深度,保留第一个被输出的标签数据,过滤后的RFID数据保持原来的采集顺序,提高标签批量读取性能,仿真实验表明,采用该算法能有效提高对计量器具物资标签的批量读取效率,降低执行时间,稳定性能较好,吞吐性能优越,在大型物流物资收发和存储等领域具有较好的应用价值。 相似文献
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《科技风》2021,(21)
随着科技的不断发展和进步,RFID的广泛应用于物流、制造及公共信息服务等。RFID技术与网络通信、大数据分析等技术相结合,实现全世界范围内的指定物品信息共享、关键环节跟踪、信息验证。一些非法分子趋于利益诱惑,利用其技术的算法弱点非法复制、伪造和变造标签,使RFID系统全面受到了潜在的安全威胁。许多应对方案应运而生,然而,这些方案中多数以更新系统或者更换硬件为代价,提高系统的安全性。研究UHF RFID射频通信加密技术,不影响RFID技术性能、标签成本却更加安全可靠;同时增加了多种应用,却使用现有硬件资源;用技术解决安全、防伪、识别、管理等应用领域。RFID的核心是RF射频通信和加密技术,以下将简要描述UHF RFID射频通信加密技术的内容。 相似文献
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射频识别系统工作时,可能会有一个以上的电子标签同时处在读写器的作用范围内,如果有两个或两个以上的电子标签同时发送数据时就会同时出现通信冲突,数据相互干扰（碰撞）;碰撞是RFID技术的常见问题。解决此问题的算法主要是二进制搜索算法,能够快速地识别所有标签。 相似文献
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在RFID系统数据通信的过程中,数据传输的完整性和正确性是保证整个识别系统数据通信性能的关键技术。系统数据传输的完整性和正确性的降低主要有两个方面的原因,即外界的各种干扰及多个标签和多个阅读器同时占用信道发送数据产生碰撞。可以通过数据校验的方法解决外界对RFID通信过程的干扰;而防碰撞算法可以解决标签和阅读器的碰撞。 相似文献
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Marjorie Armstrong-Stassen Margaret Landstrom Ramona Lumpkin 《The Information Society》1998,14(2):153-164
This study examined how students who had no prior experience with videoconferencing would react to the use of videoconferencing as an instructional medium. Students enrolled in seven different courses completed a questionnaire at the beginning of the semester and again at the end of the semester. Students at the origination and remote sites did not differ in their reactions toward videoconferencing but there was a significant difference for gender. Women reacted less favorably to videoconferencing. Compared to the beginning of the semester, students reported significantly less positive attitudes toward taking a course through videoconferencing at the end of the semester. There were no significant differences in students' attitudes toward videoconferencing across courses at the beginning of the semester but there were significant differences across the courses at the end of the semester. The results suggest the need for better preparation for both students and instructors. 相似文献
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A joint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology his co-workers from Norway US Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells suggesting that China's projected climate warming could decrease the pest's numbers. The study was published in Proceedings of the National Academy of Sciences on September .…… 《中国科学院院刊(英文版)》2008,22(1):6-7
Ajoint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology and his co-workers from Norway, US and Swiss have indicated that historical outbreaks of migratory locusts in China were associated with cold spells, suggesting that China＇s projected climate warming could decrease the pest＇s numbers. The study was published in Proceedings of theNational Academy of Sciences on 17 September, 2007. 相似文献
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Caroline Haythornthwaite 《The Information Society》2001,17(3):211-226
A computer-mediated group is a complex entity whose members exchange many types of information via multiple means of communication in pursuit of goals specific to their environment. Over time, they coordinate technical features of media with locally enacted use to achieve a viable working arrangement. To explore this complex interaction, a case study is presented of the social networks of interactions and media use among members of a class of computer-supported distance learners. Results show how group structures associated with project teams dominated who communicated with whom, about what, and via which media over the term, and how media came to occupy their own communication niches: Webboard for diffuse class-wide communication; Internet Relay Chat more to named others but still for general communication across the class; and e-mail primarily for intrateam communication. Face-to-face interaction, occurring only during a short on-campus session, appears to have had a catalytic effect on social and emotional exchanges. Results suggest the need to structure exchanges to balance class-wide sharing of ideas with subgroup interactions that facilitate project completion, and to provide media that support these two modes of interaction. 相似文献
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《中国科学院院刊(英文版)》2008,22(1):2-3
CAS should stick to the principle of rendering service to, and giving impetus for, the development of China＇s science enterprise by making S＆T innovations, said CAS President LU Yongxiang. The CAS president made the remarks in a recent talk to communicate the gist of the winter session of the Party＇s Leading-member Group at CAS, which was held from 7 to 11 January in Beijing. 相似文献
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Electronic data interchange (EDI) provides means for interorganizational communication, creates network externalities, requires an advanced information technology (IT) infrastructure, and relies on standards. In the diffusion of such innovations, institutional involvement is imperative. Such institutions contain governmental agencies, national and global standardization organizations, local government, and nonprofit private organizations like industry associations. The last type of organizations we call intermediating institutions. They intermediate or coordinate ("inscribe") the activities of a group of would-be adopters. Unfortunately, little is known of how these organizations shape the EDI diffusion trajectory. In this article we examine one specific type of intermediating organizations?industry associations?and how they advanced the EDI diffusion process in the grocery sectors of Hong Kong, Denmark and Finland. We identify six institutional measures, placed into a matrix formed by the mode of involvement (influence vs. regulation) and the type of diffusion force (supply push vs. demand pull), that can be mobilized to further the EDI diffusion. Industry associations were found to be active users of all these measures to varying degrees. Their role was critical especially in knowledge building, knowledge deployment, and standard setting. Furthermore, institutional involvement varied due to policy and cultural contingencies and power dependencies. 相似文献
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《中国科学院院刊(英文版)》2008,22(1)
With great care, Dr. ZHOU Zhonghe takes out a package wrapped by cotton tissue from a drawer and says: "This is the gem of our collections: the fossil of a bird that lived 125 million years ago!" Then, pointing at a tiny mound, he explains: "Look, this is the claw and that is the head. It was in the egg shell and ready to hatch ... The species fell into a family of waterside inhabitants." 相似文献
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Puay Tang 《The Information Society》1998,14(1):19-31
The increasing prospects of digital piracy has prompted the perceived need by electronic publishers to adopt technical systems of protection, and governments to reform their copyright laws. This article is a preliminary study of the management of intellectual property by electronic publishers, defined as those involved in the production of online databases, and CD-ROMs. It focuses on three main issues: (1) how electronic publishers view the increasing threat of piracy; (2) the methods of protection employed to protect intellectual property in digital format; and (3) the importance of technological protection of intellectual property in electronic publications. The analysis is based on a sample of 23 UK electronic publishers. The interviews revealed an interesting assortment of protection methods and did not show that technological protection was a preferred way. Instead, the means of protection, in addition to copyright law, comprised niche markets, pricing, trust, bad publicity, and nontechnical and technical means. 相似文献
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Milton Mueller 《The Information Society》2001,17(3):151-163
Long-standing conflict between domain name registrants and trademark holders prompted the Internet Corporation for Assigned Names and Numbers (ICANN) to create a global, mandatory arbitration procedure known as the Uniform Dispute Resolution Policy (UDRP). The UDRP has been used in 2166 cases involving 3938 domain names as of 1 November 2000. The policy gives the initiator of a complaint, generally a trademark holder, the right to choose which ICANN-accredited dispute resolution service provider (RSP) will handle the case. During the preparation of the UDRP,some feared that complainant selection would lead to "forum shopping" that might bias the results. This article performs a statistical assessment of the forum-shopping thesis and finds support for it. There are statistically significant differences in the various RSPs' propensity to take away names from defendants; there are also major differences in the number of cases brought to each RSP. RSPs who take away names have the larger share of cases. The study examines other variables that might explain differences in market share, such as price, the plaintiff's nationality, or the time taken to decide a case. It finds that nationality and time also are correlated with market share. The study concludes that shopping for a favorable outcome is an important factor in the UDRP. 相似文献
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Prof. Raymond C.K. Chen a neuropsychologist with the CAS Institute of Psychology has made novel progress in his studies of schizophrenia. His work has been reported by a recent issue of Behavioural Neurology.…… 《中国科学院院刊(英文版)》2008,22(1):15-15
Prof. Raymond C.K. Chen, a neuropsychologist with the CAS Institute of Psychology, has made novel progress in his studies of schizophrenia. His work has been reported by a recent issue of Behavioural Neurology. 相似文献
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《中国科学院院刊(英文版)》2014,(3)
<正>In Xishuangbanna,one of China’s most biodiverse regions,landscape has changed dramatically during the past three decades due to the conversion of tropical rainforest to rubber plantations.In steep areas,terraces are often constructed before planting rubber trees,which causes two important changes in the soil:the destabilization of soil in the bench terraces and the increased vulnerability of unvegetated riser faces to erosion.Few studies have documented the nature and intensity of erosion on bench terraces.Prof.LIU Wenjie and his colleagues from the Xishuangbanna Tropical Botanical Garden(XTBG)conducted a study in Menglun County(21°5′39″N,101°15′55″E),Xishuangbanna to evaluate the influence 相似文献