数字通信中的基带滤波器设计

从数字通信基带滤波原理出发,分析了无线数字通信对滤波器参数的要求,并分析了FIR滤波器实现的结构形式,最后结合工程设计阐述了应用FPGA硬件技术,实现的一种能够广泛应用于无线通信系统的FIR滤波器。     

用于WiMAX的FIR滤波器的研究与FPGA实现

文章根据WiMax网络的技术特性,设计了一种可用于数字下变频模块中的高阶FIR滤波器。探讨了实现FIR滤波器的两种算法:分布式算法和乘加算法,比较其优劣。根据实际情况,对分布式算法进行了一定的改进。随后对FIR滤波器进行了Matlab建模,最后用FPGA将其实现,并对结果进行仿真。     

FIR数字滤波器的FPGA设计与实现

提出了一种基于现场可编程门阵列器件FPGA并利用窗函数法实现一个16阶线性FIR．数字滤波器的设计方法。对于在FPGA中实现FIR．滤波器的关键部分——乘加运算,该设计主要采用了将乘加运算转化为查找表的并行分布式算法,与传统串行算法相比,这种方法可极大地减少硬件电路的规模,提高电路的执行速度并且充分利用了FPGA丰富的查表资源。从时域上对基带信号可直接进行成形,因此其实现的滤波器性能优于用DSP和传统方法实现的滤波器,特点是算量较小、精度高,更适用于实时系统。     

基于进位存储加法器的数字滤波器的设计

讨论了进位存储加法器的基本原理,并采用进位存储加法器作为FIR滤波器在FPGA硬件上进行的设计方案。以一个16阶的低通滤波器为例进行了实验仿真和调试。并验证以进位存储加法器实现的滤波器的性能优于用其他传统加法器方法来实现的滤波器。     

基于FPGA的新型高阶FIR滤波器设计

从FIR(有限冲击响应)滤波器的公式以及最基本的直接型结构出发,系统的分析了高阶FIR数字滤波器在FPGA(现场可编程门阵列)中的两种实现方法(1.用硬件描述语言(HDL)编程2.调用XILINX公司的IP核),并提出一种针对高阶FIR数字滤波器的优化算法,最后通过设计一个630阶的带通滤波器,将硬件仿真计算结果与输入的原始信号做对比,验证了这两种方法的可行性与正确性。     

基于FPGA的FIR数字滤波器的设计与实现

FIR数字滤波器具有稳定性高、严格的线性相位等特点,因而在现代数字信号处理中得到广泛的应用。文章采用分布式算法,给出了利用现场可编程门阵列器件（FPGA）并采用窗函数的方法来实现FIR滤波器的设计。整个程序采用Verilog HDL语言编写,并在ISE Foundation环境下进行了仿真,结果表明该方法的可行性。     

基于MATLAB的FIR数字滤波器的设计与实现

简要介绍了FIR滤波器的设计基础和利用窗函数设计FIR滤波器的方法,运用MATLAB语言实现了低通FIR滤波器的设计仿真。     

基于matlab窗函数的FIR带通滤波器设计

本文利用matlab布莱克曼窗实现了FIR带通数字滤波器的设计,设计结果符合FIR数字滤波器技术指标要求。     

基于MATLAB和DSP实现的FIR数字低通滤波器

设计了利用Matlab与DSP技术相结合的FIR数字滤波器的软件、硬件实现方法。文中采用窗函数法设计FIR数字滤波器,给出了低通滤波器的Matlab仿真波形,介绍了在DSP硬件系统中的实现过程,实现了对信号的FIR滤波处理。     

数字低通滤波器的matlab实现

利用Parks-MaClellan算法实现了FIR低通数字滤波器的设计,设计结果符合FIR数字滤波器技术指标要求。     

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