TD-SCDMA上行链路波束赋形算法研究与仿真

研究了TD-SCDMA系统等距线形智能天线阵列的原理,上行链路最大输出功率赋形算法与线性最小约束最小方差波束赋形.搭建上行链路仿真平台,测试了两种波束赋形算法的性能.结果表明,线性最小约束最小方差算法在保证总功率不变的前提下,使得本用户信号的功率最大,因而能够使得干扰用户信号和噪声得到较好地抑制,可以将该波束赋形算法应用于TD-SCDMA系统上行链路.     

物联网环境下传感器路由探测算法

在物联网环境下无线传感器路由节点的准确探测实现节点的定位识别,将在传感器节点的故障监测和目标识别等领域具有较好的应用价值。传统的传感器路由探测算法采用源结点追踪定位方法实现传感器路由探测,当源节点受到外界电磁场干扰时,路由探测准确性不好。提出一种基于最短路径搜索的物联网环境下无线传感器路由探测算法。构建了物联网环境下的传感器网络分布结构模型,进行传感器路由信息的量化分析,采用最短路径搜索方法进行路由传输信息的跟踪探测,采用线性阵列结构部署路由节点,能实现路由节点探测和定位的最短路径搜索。仿真结果表明,采用该算法进行物联网环境下传感器路由探测提高了传感器节点的生存概率,路由探测能量消耗较小,路由节点定位准确,提高了目标节点的识别和监测能力。     

基于宽带MVDR波束形成的稀疏阵被动测向方法

稀疏阵处理高频信号进行被动测向时,波束图会产生栅瓣而导致目标方位模糊.针对这一问题,研究基于宽带最小方差信号无畸变响应(MVDR)波束形成的稀疏阵被数的情况下,宽带MVDR波束形成在抑制稀疏阵栅瓣方面具有显著的效果.     

基于物联网技术的家庭火灾监控硬件系统

本文提出了一种基于物联网的嵌入式家庭火灾监控系统。以气体、烟雾、温度、红外线等传感器组成信号采集电路,以Zig Bee单芯片CC2430为核心,构建信息采集无线网络平台,以RT3052为控制、处理核心搭建网关控制平台,使无线网络通信平台接入Internet,实现了远程监控。     

基于无线网络的农田信息远程监测系统的设计与开发

为解决目前农田自动监测系统存在的布线困难、成本高和灵活性差等问题,本文构建了基于无线传感器网络的农田信息远程监测系统。该系统的传感器节点负责农田土壤墒情、温度、湿度、光照强度和二氧化碳浓度的采集功能,并通过无线传感网络将数据发送给汇聚节点,汇聚节点通过RS232串口将数据传送给数据监测中心。传感器节点的硬件主要由一个传感器模块、处理模块、无线通信模块和电源模块组成。试验证明,该系统可以实现了对农田信息的远程实时监测,有效提高农田管理的信息化和自动化水平,大大提高了劳动效率,降低了人工劳动强度。     

引入外加黏附信号的无线中继传感器远程通信

引入外加黏附信号,利用传统无线中继传感器通信系统中设备,借助外加黏附信号的补充信号能量和维持信道特性的功能,实现无线中继传感器远程通信。提出的引入外加黏附信号的无线中继传感器远程通信方法,通过中继器的黏附纯化和黏附交换形成高黏附度信号对,进而建立远程无线中继传感器信道,通过对无线中继传感器通信链路进行黏附交换实现了复杂网络的无线中继传感器远程通信。仿真实验表明,构建的远程无线中继传感器通信系统的传输效率随着系统通信用户的增多而增加,该系统能有效提高无线中继传感器通信的传输效率和通信距离。     

基于物联网的远程视频监控优化方法研究

设计远程视频监控系统的关键是在于对视频图像的实时传输和数据通信设计,远程视频监控系统中接收端所显示的视频图像通常受到吞吐量和传输时延等因素的影响,导致远程视频监控实时性和保真性不好。提出一种基于物联网的远程视频监控优化方法。设计基于物联网的远程视频数据采集系统模型,构建远程视频监控识别的量化编码算法,使用RLE行程编码和Huffman编码来完成压缩任务,采用三级放大器进行逐级放大,进行远程视频监控。仿真结果表明,采用该方法进行远程视频监控,能准确实现对远程监控视频序列量化编码,提高远程视频监控的视频保真度和峰值信噪比,同时能提高视频传输效率,实现了视频远程监控的实时无损传输。     

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。     

基于巡检机器人的电网地下输电线路状态智能监测技术

为了提高电网地下输电线路状态智能监测准确度,提出一种基于巡检机器人的电网地下输电线路状态智能监测技术.通过巡检机器人的线路信号采样模块采集数据并将其反馈至机器人主体,通过机器人主体的嵌入式微控制器与无线模块处理所采集的图像数据,利用HOG特征识别采集图像并提取图像特征,通过远程监控系统的无线模块接收机器人主体传送的实时...     

基于B/S的建筑灾情远程监控系统

为了有效保护高层建筑内人员的生命和财产安全,采用PHP和my SQL数据库技术设计了一个基于无线传感器网络的建筑灾情远程监控系统。该系统实现了建筑内环境参数和建筑结构参数的实时采集,传感数据经灾害判定算法处理分析后,将结果以Web形式发布,用户可以通过移动或固定终端远程登录监控系统网页查询建筑灾害信息,并可通过网页对监控系统进行远程控制。     

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.     

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.     

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.     

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