基于MSP430F449的便携式高精度流量计的设计与开发

本文介绍了一种便携式高精度流量计,它是以TI的MSP430F449为控制芯片,配有显示模块、键控模块、信息检测及输入模块等。本文还具体阐述了该流量计的工作原理、总体设计及硬件电路设计和软件设计。该流量计适用于各种复杂环境,并可以和其他上下游设备结合,实现流量控制的高精度及携带方便。     

超声波流量计的研究

超声波流量计采用高精度时间测量芯片TDC-GP2进行时间测量,保证了测量的精度。本设计采用时差法原理进行测量流体流速,进而计算出瞬时流量。论文从流量计的发展历史和背景到超声波流量计的原理介绍了超声波流量计。     

基于单线接入红外感应电路的设计

文章介绍了基于热释红外传感器的工作原理的单路控制开关电路,给出了一种被动型热释电红外感应器的结构原理及其应用电路。该系统电路以BISS0001芯片为核心,通过热释电红外传感器探测信号,由信号输入调整、采集、放大、滤波、数据处理、延迟设计、可控硅控制电路等功能模块组成。     

ATM over ADSL技术在智能钻柱中的应用

本文介绍了如何利用ADSL通信方式完成智能钻柱的通信系统,提出了ATM over ADSL技术在智能钻柱通信系统中的应用方法：将ADSL通信线路嵌入到钻杆中,通过ADSL专用调制解调芯片在钻井的同时将数据处理后传输到地面,利用ATM网络将数据发送到远端处理中心,然后反馈控制信息控制钻井。利用TCM／QAM编码技术和DMT调制技术提高通信质量。该课题将钻井与测井一体化,实现了钻井的实时控制。     

基于nRF9E5的智能家居控制系统

该文介绍了以MCU、内嵌8051的RF收发芯片nRF9E5为核心,通过远程指定电话控制,由DTMF集成电路MT8880、语音录放芯片ISD4001和RF收发芯片nRF905等芯片组成的智能家居系统,并给出了该系统主机和分机的基本原理以及设计方案。     

CEMS烟气连续监测系统在火电厂中的应用及维护

CEMS系统由SO2/O2/NOX分析仪、烟尘仪、流量计、压力变送器、湿度/温度计及数据处理单元（DAS）等部分组成。文章详细介绍了CEMS各个组成部分及其在火力发电厂中的应用和维护。     

ELMO伺服系统在某控制中的应用

本文主要论述了Elmo伺服系统在进气道试验流量计控制中的应用。该系统通过CAN总线成功的完成了复杂的控制过程,简化了进气道试验流量计的控制过程,达到了预期的目标。     

基于国密算法的超高频读写器设计

本文设计出一种基于国密算法的桌面式超高射频识别系统(UHF RFID)读写设备的新方案。该读写设备采用了国密算法进行安全握手认证,射频收发芯片采用IBAT1000芯片,控制芯片采用AM3358和STM32微控制芯片,工作频率为840-960MHz,可对汽车电子标识进行数据读写。重点介绍了读写设备硬件系统设计具体方案和射频收发电路工作原理,同时介绍了国密算。     

一种LED驱动控制专用电路设计仿真

本文介绍了一种LED驱动控制专用芯片的设计,按照设计要求,该芯片将与TM1623兼容,内部集成有MCU数字接口、数据锁存器、LED高压驱动、键盘扫描等电路,完成了芯片的硬件语言描述,给出了仿真结果。     

基于TMS320F2812的SVPWM控制

介绍了利用TI的DSP电机控制芯片TMS320F2812实现SVPWM的方法。该控制方法速度快、精度高,在电压型逆变器中能产生更少的谐波并减少开关损耗。     

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.     

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.     

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.     

To serve and promote science development via innovation

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.     

Tracing the origin and early radiation of birds——Paleornithologist ZHOU Zhonghe

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."     

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.     

The Information Environment and Universal Service

This essay focuses on universal service and the Internet as means to support social and political participation. The emphasis on access to telecommunications systems in conventional approaches to universal service is contrasted with access to content. A model of the information environment is described that accounts for the roles of content and conduit, both of which are necessary conditions to achieve true access. A method is outlined for employing information indicators to observe or measure the information environment.     

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.