基于Zigbee的温室WSN系统设计

传统温室大棚常采用人工方式对温度、湿度等环境参数进行监控,费时费力。针对其缺陷,对基于Zigbee技术的无线传感器网络技术在温室大棚的应用进行分析研究,设计了基于2430芯片的节点硬件电路,对RFD终端、路由器及网络协调器节点软件进行了研究及设计。从实际运行情况可见,终端传感器采集到的数据可以通过无线网络上传给上位机进行显示、存储打印等。基于Zigbee的温室WSN系统可以降低工作者的劳动强度．便于组网和推广。     

基于随机寻址RFID阵元分布的车辆密度参量估计

车流量的不断增大,城市变得愈加拥挤,需要进行车辆密度估计,进而构建有效的车辆防碰撞系统。提出一种基于随机寻址RFID阵元分布的车辆密度参量估计算法,进行ZigBee和参量估计的车辆防碰撞预警系统设计。首先实现了基于ZigBee的车辆间的通信组网系统模型构建,得到了ZigBee组网与车辆碰撞预警方法,利用随机寻址RFID方法进行ZigBee的车辆间的通信组网系统模型构建,采用贝叶斯近似方法建立均匀矩形阵列,车辆作为阵元分布在均匀矩形网格中,以此描述车流动态变化过程,根据角度变化得到车流的方位和速度信息,实现车辆密度参量估计和防碰撞预警系统设计。系统实验结果表明,该算法和系统进行车辆密度参量估计,估计精度较高,信息全面准确。通过准确的车辆密度参量估计,提高了车辆防碰撞预警系统的性能。     

高压电缆金属护套环流监测系统

正本文介绍了一种基于LabVIEW的高压电缆金属护套环流监测系统,监测系统使用NILabVIEW2011平台软件为基础进行开发,本系统采用光纤网络组网,系统由护套环流采集单元、电源管理单元、光电转换单元和嵌入式工控机组成。实时监测电缆护套环流和软件报警,运用MySQL数据库实现数据管理等操作。通过使用高压电缆金属护层监测     

基于ZigBee和CDMA的水情远程监测系统设计

针对偏远地区水情数据远程监测的实际需求,文章进行了基于zigbee协议和CDMA通信技术的远程数据采集传输系统的设计开发。以支持zigbee协议的芯片CC2530来构建传感器节点和中心节点,以CDMA无线通信模块构建能与internet进行数据传输的网关。传感器节点采用星型拓扑结构组成无线传感网络后,采集数据传给中心节点,再通过ARM处理器驱动CDMA模块实现数据的远程传输。该监测系统低功耗、易组网、易安装,适合大区域的远程无线实时监测。     

基于Zigbee技术的温室大棚监测系统的研究

我国农业的发展逐步在信息技术发展的带动下转向智能化,在目前温室大棚管理智能化迫切需求的背景下,本文构建了一个基于Zig Bee技术的温室大棚监测系统。该系统利用Zig Bee传感器节点采集数据,该设备集成了传感器和Zig Bee无线单片机的功能,再通过控制管理层将数据提供给应用层的用户访问,这样用户可以利用移动终端对传感器采集到的温室环境各个数据(温度、湿度、光照、CO2浓度)进行实时监控。     

zigbee技术在农业温室大棚中的应用研究

结合物联网和我国农业发展现状,本文设计了一个基于zigbee技术的农业温室大棚监测系统,首先,详细地研究zigbee技术,包括zigbee协调器、zigbee终端节点和网络模型等;其次,结合实际应用搭建了基于zigbee技术的农业温室大棚监测系统,对农业温室大棚的温湿度等信息进行采集和监测;最后,经过系统的上位机和手机app功能测试,表明该系统性能稳定,操作简单,实用性强。     

基于物联网和ZigBee的化工园区危险源监控系统设计

针对传统便携式检测仪不能实现对化工园区危险源的实时自动监控,提出了一种基于物联网和ZigBee无线通信技术对化工园区进行实时可靠数据采集和监控的系统.首先,对系统组成框架进行了描述和定义,在此基础上对系统的硬件即终端节点和协调器节点进行了设计,同时对终端节点入网采集数据以及协调器组网收集和传送数据的软件流程分别进行了描述,从而实现了化工园区监控物联网的设计.实验结果证明文中系统可以正确、实时地采集监测区域的数据,并能进行有效地分析,在出现了异常情况时能提示用户采取应急措施,最大程度避免事故发生.     

一种基于物联网的农田大棚实时监测报警系统

本文介绍一种基于物联网的农田大棚监测报警管理系统,对农田大棚中一些农作物生长状况进行监测:包括数据采集单元、数据接收设备、移动巡视设备、射频识别设备及数据存储服务器。系统能够自动采集温室大棚里的照度、土壤温度、土壤湿度等环境参数,自动测出各项参数的临界值然后进行报警。     

基于RFID和LABVIEW的温度监控系统

本技术基于RFID技术和LABVIEW的温度监控系统,系统包括下位机和上位机。下位机以STM32芯片为核心,同时包括RFID电子标签、读写器和接收器;上位机采用LABVIEW编写程序;下位机实现对温度的实时采集,通过串行接口上传信息到上位机;上位机实现对下位机温度信息的采集和分析。     

基于ZigBee技术的温度采集系统的设计

针对有线温度采集系统存在的诸多问题,提出了利用ZigBee技术实现无线温度采集系统的设计方案,本系统采用星型网络拓扑结构组建ZigBee无线网络,利用CC2530芯片构建强大的网络节点,对温度传感器采集的温度信息进行处理,并通过ZigBee无线网络发送给协调器,然后由协调器通过串口发送给PC机,从而实现实时监测。     

Students' Reactions to the Introduction of Videoconferencing for Classroom Instruction

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.     

Cooler temperatures inductive to locust outbreaks

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.     

Exploring Multiplexity: Social Network Structures in a Computer-Supported Distance Learning Class

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.     

The Role of Intermediating Institutions in the Diffusion of Electronic Data Interchange (EDI): How Industry Associations Intervened in Denmark, Finland, and Hong Kong

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.     

Low doses of a red wine ingredient figh diabetes in mice

Aresearch group led by Prof. ZHAI Qiwei from the Institute for Nutritional Sciences under the CAS Shanghai Institutes for Biological Sciences has discovered that even relatively low doses of resveratrol--a chemical found in the skins of red grapes and in red wine--can improve the sensitivity of mice to the hormone insulin, according to a report in the October,2007 issue of Cell Metabolism. As insulin resistance is often characterized as the most critical factor contributing to the development of Type 2 diabetes, the findings“provide a potential new therapeutic approach for preventing or treating” both conditions, the researchers said.     

How Electronic Publishers are Protecting Against Piracy: Doubts About Technical Systems of Protection

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.     

Rough Justice: A Statistical Assessment of ICANN's Uniform Dispute Resolution Policy

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.     

Prevalence of soft neurological signs in Chinese people

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.     

Molecular motor assembly of a biomimetic system

Active biological molecules and functional structures can be fabricated into a bio-mimetic system by using molecular assembly method. Such materials can be used for the drug delivery, disease diagnosis and therapy, and new nanodevice construction.     

Monoculture Rubber Plantations Have Negative Ef ects on Controlling Splash Erosion

<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