一种高效利用缓冲资源的自适应RED算法

RED算法是一个典型链路拥塞控制算法,RED算法提高了TCP连接的吞吐量、较少了队列长度和能按网络拥塞状况进行丢包以反馈给发送端．但是对于RED算法的参数敏感性没有根本性改善,一些改进的算法如ARED等自身存在参数设置问题,本文主要讨论在分析网络状态和拥塞程度实现基于路由队列资源（缓冲）自适应调节分组丢弃策略从而修改RED算法丢包策略,使路由队列长度稳定在参考值附近．将这种新算法明名为DIKED     

基于流量预判的校园选课网络拥塞控制方法

在学校的选课系统中,如果多名学生同时选择同一门课程,这种瞬时增大的数据流量流动的倾向会造成数据的分布均匀性较差。传统的校园网络选课系统多是基于CS结构,如果服务器数据源节点动态传输数据过于集中,会造成瞬时数据量猛涨,导致选课网络信道发生拥塞现象,选课数据无法及时传输到终端,造成选课系统存在较大延迟。为了解决上述问题,提出了一种基于流量预判算法的校园网络选课系统的拥塞控制策略,通过获取数据流量分布情况,进行流量参数估计;通过流量预测,判断信道流量拥塞程度,从而实现校园网络的拥塞分流控制。实验证明,这种基于流量预判算法的拥塞控制方式提高了校园网络选课速度,取得了令人满意的效果。     

基于模糊神经网络的RTT智能预测算法

在网络拥塞控制的重要参数中,RTT（Roundtriptime）尤为突出,因为它能对网络所发生的拥塞作出较早的反映。所以对RTT的精确预测程度,无论是对网络拥塞控制还是流量、带宽估计都很有意义。分析了RTT的特性,发现其有很强的高频噪声,因而采用低通滤波和MBP网络相结合的RTT预测策略。实验表明,即使在网络状况较忙的情况下,也能获得很好的预测结果。     

多瓶颈网络环境下TCP公平性算法的研究

在保证网络数据传输可靠性的基础上,数据流之间的公平性是算法设计的重要的性能指标之一.根据网络层的显示拥塞指示MarkingRelay ECN(explicit congestion notification,ECN)技术,研究了在多瓶颈网络环境下TCP数据流的公平性,提出了一种改进的TCP拥塞控制算法,并使该算法在IP网络中得以实现.     

一种基于权值动态调整的MPTCP自适应拥塞控制算法

随着计算机网络技术的发展,用户对网络资源访问速度的要求越来越高.特别是近些年语音、图像以及视频等多媒体数据大量出现在互联网上,网络的拥塞问题也变得日益严重,拥塞控制对于保证网络的稳定性也具有非常重要的作用.本文提出了一种改进的MPTCP自适应拥塞控制算法,将权值动态调整策略融入拥塞控制中.算法的核心思想是当某一路径接收到数据包则增加其权值,相反如果丢失了数据包则降低其权值,修改权值时综合考虑了前一个时刻该路径的权值及其拥塞窗口的大小.仿真实验结果表明,本文提出的MPTCP拥塞控制算法改进方案有效地提高了系统的吞吐量,并且能够使得网络资源得到公平的利用.     

无线传感器网络中的拥塞控制技术

无线传感器网络的拥塞控制技术是这一领域研究的重要方向之一.传感器网络的特点决定了网络容易发生拥塞.传统有线网络的拥塞控制技术不适用于传感器网络.本文对于当前的拥塞避免,拥塞检测和拥塞解除策略进行了分析和比较,并且对于拥塞控制技术的研究和发展方向进行了展望.     

基于TCP拥塞控制的研究与分析

随着Internet的不断发展,网络上出现了大量流媒体和组播流量,同时也带来了拥塞现象的发生。首先介绍了拥塞产生的原因,并详细分析了基于TCP拥塞控制的机制。指出了当前网络技术环境中拥塞控制的新焦点。     

计算机网络拥塞控制算法研究

为了避免网络拥塞Internet主要依赖TCP端到端拥塞控制,互联网的稳定运行有一部分要归功于以TCP为代表的端到端拥塞控制机制,这个机制起了很大的作用。但是由于互联网上的应用和用户的增多,互联网规模的爆炸,这个机制已经不能全面的满足网络中各种复杂应用的需求,拥塞已经成为迫在眉睫的问题。在本文中,当前的TCP/IP网络的拥塞控制两个层,并以此为基础针对网络的实际应用需求做了深入研究。     

基于TCP的拥塞控制技术研究

就数据流在拥塞控制方面的发展进行了研究，在介绍TCP基本机制的基础上，对TCP拥塞控制的改进机制进行了讨论，探讨了网络拥塞出现的原因及TCP拥塞控制的基本策略，论述了TCP拥塞控制的改进方案，并提出了其进一步的研究方向。     

电网监控系统中网络风暴的抑制

网络风暴是数据广播造成的网络拥塞,使网速大大降低,甚至网络瘫痪;通过DF1800电网监控系统网络结构而建立分析的模型,分析网络风暴产生的原理,提出有效的解决方案,探讨了如何抑制在电网监控系统中的网络风暴。     

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