基于ZigBee的物联网智能LED路灯控制系统设计

设计了一种基于Zig Bee的物联网智能LED路灯控制系统。路灯节点采用AVR单片机作为核心处理芯片,通过光电传感器检测外部信号,可根据环境明暗、交通情况和定时开关等条件以不同方式控制LED灯照明;使用MBI1802驱动芯片恒流驱动LED灯,功率在20%¹00%范围内可调,调节误差<2%,恒流电流偏差<±1.7%;以Zig Bee无线通信网络与控制中心进行远程控制、故障报警等信号传输,实现了路灯智能化、远程化的节能控制。     

大功率LED路灯照明驱动的研究

目LED路灯驱动电源存在着输出功率低、转换效率差、功率因数不高、输出特性不稳定及可靠性差等问题,严重制约了LED路灯的推广使用,本文针对以上问题优化了LED路灯驱动电源电路.采用了HV9910这款灵活简单的LED驱动器IC提供电源,PWM自动调节实现恒流输出,稳压管过压锁定实现空载保护,电磁隔离和光隔离实现隔离输出.本设计体积小,微调反馈电路可设置作为为LED驱动常用的350mA或700mA恒流输出,简化了电路的设计,提高了驱动电源的可靠性.     

基于PWM调光的多功能LED台灯设计

传统台灯功能单一、能耗大、亮度不可调等缺点。本设计的多功能LED台灯以STC89C52RC单片机为智能控制,PT4115恒流驱动,10等级PWM调光,有效保护LED灯光亮度适合,达到绿色环保,高效节能、实用可靠等目的。     

太阳能LED路灯的智能调光系统

随着太阳能光伏发电技术和LED照明技术的发展,太阳能LED路灯已进入了城市照明领域。本文介绍了一套基于ATmega16的太阳能LED智能调光系统,系统通过BH1750FVI传感器采集外界的光照强度,将采集的数据反馈给ATmega16单片机,经处理后产生PWM信号,从而控制XL6003降压恒流源的驱动,最后实现了能自由控制LED灯的亮度的节能照明系统,从而提高具有提高用电效率、节约电能以及保护环境的作用。     

基于光传感器和单片机的校园路灯控制系统设计

本系统以LED路灯为控制系统的研究对象,以STC 89C51单片机为控制核心,设计了一个路灯自动控制系统.该系统利用时钟芯片DSI302计时,根据当地天黑天亮的时间对单片机进行编程设定,从而实现对路灯开关状态的时间控制;由光敏器件对环境光照度的采集,将采集信号送给单片机,当白天天气恶劣光线昏暗时,打开路灯照明.该系统具有时间控制、光敏控制相结合的路灯开关智能控制功能,同时还采用声音控制和红外控制作为辅助控制,对校园路灯乃至超市照明等其他光源的设计有参考使用价值.     

基于ZigBee的智能照明RGB LED驱动技术研究

随着互联网和半导体技术的发展,人们对智能化的生活需求越来越强烈。"互联网+"风靡全国更是推动了智能照明系统在智能建筑和家居自动化的快速进步,而LED驱动技术是智能照明必不可少的子系统,本文设计了RGB LED恒流驱动电路,能通过ZigBee RF4CE/ZLL通讯和三色白光可调。     

浅析大功率LED工矿灯设计

大功率LED灯具具有亮度高、恒流驱动、发热量高等特点,因此对散热要求更加严格。在介绍LED灯具设计的主要内容基础上,重点突出整个散热通道的热设计,并以LED工矿灯为例,分析设计中存在的问题及解决办法。     

可调光大功率LED驱动器的研究与设计

介绍一种非隔离的单级功率因素校正恒流可调光大功率LED驱动电源。输入级采用CL滤波电路和填谷电路,有效地抑制了噪声和纹波干扰,提高了功率因素。通过电源管理芯片BP2808控制buck型降压拓扑,能使LED稳定地工作,并有效延长LED的使用寿命,并在开路、短路、过温等各种异常状态时保护驱动电源。利用红外遥控器发射红外信号,并通过51系列单片机接收处理红外信号和产生PWM波,能实现LED的调光。实验测试表明,该驱动电源性能可靠稳定,效率高,调光性能好。     

基于单片机的太阳能LED路灯硬件分析

介绍了一个为节约能源保护环境而设计的安全可靠的基于单片机的太阳能LED路灯控制系统,该系统从太阳能LED路灯系统电池板、蓄电池、LED照明灯具和控制芯片的选择来优化LED路灯控制系统,从而达到对目前路灯控制系统所存在的硬件缺陷进行完善。     

基于Zigbee的无线网络风光互补LED路灯监控系统设计

本文介绍了一种基于ZigBee技术的风光互补LED路灯的监控系统。它能及时、准确的检测到蓄电池电压、电流、太阳能电池板等路灯的各项参数,并通过GPRS上传至监控中心,又能对路灯的开关及亮度等进行控制,方便管理和维护,具有巨大的市场应用价值。     

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.     

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.     

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.     

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.     

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.     

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.