基于优先级调度网络冲突避免模型仿真

随着光通信技术近年的迅猛发展,多路由网络不断改善,目前多路由网络构建技术成熟,具有较好的保护倒换机制,以满足广泛应用者的需求。现阶段的多路由网络平台系统只能单一静态运行,且在调度通信任务时,无法选择优先级并产生总线冲突,不能降低能量消耗及节省时间,影响了多路由系统的发展速度。为此,提出多路由网络总线冲突避免调度模型,通过在时间调控下调度通信任务与计算任务来降低能量消耗,有效的节能调度可避免总线冲突,并在时间限制下实现节能消耗。仿真实验表明,多路由网络总线冲突避免调度模型,实现了任务的目标优先级通信任务与任务的协同调度及能量的低消耗性能,为避免多路由网络系统总线冲突提供了帮助。     

基于射线模型的超宽带栅状路由冲突重整算法

在使用无线网格网技术建设的网络中,其拓扑结构呈格栅状,通过路由协议快速形成超宽带网络,超宽带格栅状网络路由因为协议局限导致路由冲突,需要进行路由冲突在线重整,保证网络通信协议的安全稳定。传统的重整算法采用调制码元帧格式扫频方法实现路由信道均衡,优化任务调度,当网络信道的扩展损失呈突变衰减时,路由冲突重整效果不好。提出一种基于射线模型的超宽带栅状路由冲突重整算法,使用线性异域网络编码方式构建格栅状网络环式路由模型,采用射线模型构建邻居节点网络路由统计学模型,分析路由冲突信号的超宽带特征。计算超宽带格栅状路由协议的链路跨层信息,得到网络通信信道系统函数,根据多目标优化理论,把路由冲突协议叠加到射线模型的波动方程,实现基于射线模型的路由冲突优化重整。仿真实验结果表明,该算法能有效提高路由负载的均衡度,展示了算法优越的性能。     

基于最优多属性约束的IPV6动态路由协议优化

提出一种基于最优多属性约束的IPV6动态路由协议优化方法。根据IPV6动态路由协议中数据属性的约束条件,建立最优多属性约束模型,用来描述不同属性约束条件需要符合的要求。详细描述了IPV6动态路由协议的设计方式,从而实现大范围网络通信。实验结果表明,利用这种方法进行网络通信,能够避免传统算法的缺陷,提高了通信效率,取得了令人满意的结果。     

多源单汇无线传感器网络的局部路由算法

无线传感器网络节点有着严格的能量限制，目前已有的许多路由协议假定了节点知道网络的全局信息或者让节点根据路由表进行路由。这些方式均会使网络产生较多的通信负荷，增大能量开销。结合多源单汇路由的特点，本文提出了几种局部路由算法。该算法中，节点仅根据目标节点与邻居节点的地理位置、剩余能量等信息，决定下一跳节点，最终建立到达目的节点的路径。本文首次引入了带约束后跳发射的思想，并将这种后跳发射与已有的算法相结合得到新的后跳路由算法。计算机仿真实验表明，在有数据融合的网络中，带约束的后跳－为难度路由算法使得网络的生存时间最长，较其余算法增加了网络11%和14%的工作周期数。最后又将局部路由算法进行合理改进，得到最小化平均为难度的算法，应用于无数据融合的网络中，效果很好。     

基于链路不对称性预测的机会网络路由设计

机会网络的混合路由优化设计可以有效降低冗余开销,提高数据传递成功率。传统方法采用链路代价评估和能量节省延迟容忍算法实现机会网络的路由设计,当在移动自组织网络中出现节点稀疏化调度下链路具有不对称性,降低了路由分配质量。提出一种基于改进的OLSRv2算法的链路不对称性预测控制机会网络混合路由优化算法,定义机会网络中混合置信因子概念,研究路由优化检验统计量的确定和判别系统的设计,通过OLSRv2算法引入了概率路由,在当前连通域的路由信息进行地址压缩得到最优传送概率值。仿真实验表明,采用该算法设计的机会网络路由进行网络通信,得到较小的控制开销,提高通信成功率,网络负载大幅降低。     

基于不变波束形成的WSN路由存活概率云计算

无线传感器网络WSN的路由存活概率云计算模型的优化设计可以提高WSN网络的网络复杂和数据吞吐量,在WSN网络的路由发射功率能耗具有匹配衰减特性,路由存活概率优化困难。传统方法采用灰色马尔可夫链组合模型进行存活概率预测,云计算精度不高。提出一种基于不变波束形成的WSN路由存活概率云计算优化模型,进行WSN网络云计算路由链路模型的结构设计,在WSN网络中进行任务节点信息表征,采用能量剩余度向量概率密度优化分配算法进行能量分配,把WSN的能量节点信号从阵元域变换到波束域得到阵列域,采用空间协方差矩阵逆的高阶次幂来逼近WSN的数据传输信号模型,将旋转角度控制在半功率主瓣以内,由此得到了云计算模型下WSN路由节点数据传输模型。仿真实验表明,该算法能提高WSN路由的存活概率,从而提高了WSN的吞吐量和通信能力,路由概率寻优中抑制了在WSN网络的路由发射功率能耗的匹配衰减性,通过最小的能量开销实现路由分发速率和负载效益的最大化。     

路由冲突下的语义检索嵌入式任务调度算法

在路由冲突协议下难以实现对语义检索任务的嵌入式调度,在路由冲突协议设计和网络协议识别中,由于语义检索码在链路负载导致网络通信效率低下,为了提高语义检索任务的调度能力,避免路由冲突,提出一种基于语义相似度融合的Linux嵌入式任务调度算法。通过语义相似度特征模型构建,易于实现语义检索的嵌入式任务调度和路由信息分流。对每组语义相似度特征进行特征融合,得到Linux嵌入式分流矩阵向量长度,进行特征分解,得到样本协方差,实现算法改进。仿真结果得出,算法具有较高的吞吐率和召回率,执行效率较高,检索精度优越,有效提高了语义检索嵌入式任务调度的运行效率。在语义系统构建和检索优化设计中具有较好的应用前景。     

基于蚁群拥挤度跃阶调整的交互信息调度算法

大数据库对象交互信息调度是提高网络数据库系统结构的稳定性和吞吐量的关键,通过采用UDP协议传输实时大对象数据调度,提高大对象数据的传输性能,是避免延时和丢帧的关键。提出一种基于蚁群拥挤度跃阶调整的交互信息调度算法,根据HList返回到IC Compiler中进行任务调度,根据每个节点的时序信息,采用双阈值判决条件设计,发送方需要发送数据时,时间轴划分成各个相邻的任务匹配平滑窗口模型,构建跃阶调整的自适应信息调度模型,仿真结果表明,本文算法能有效提高交互信息调度性能,节省了任务开销,缩短交互信息调度延时,降低误码率。     

一种针对非平稳网络任务调度防冲突算法研究

利用传统算法进行非平稳网络任务调度,由于非平稳网络的随机性增加,很难建立准确的任务调度模型,导致任务调度的失败。为了避免上述缺陷,提出了一种基于二叉树搜索算法的非平稳网络任务调度防冲突方法。根据非平稳网络中的相关参数,对网络信道中的数据量进行预测。利用二叉树搜索方法,对非平稳网络任务调度进行防冲突运算。实验结果表明,利用本文算法进行非平稳网络任务调度防冲突运算,能够极大地提高非平稳网络任务调度防冲突的准确性,保证了非平稳网络的性能。     

多嵌入不兼容设备的无线传感网络路由优化设计

无线传感网络通常是以无线传感节点的能量和信号传输路径的关系构建路由协议的。传统的LEACH协议没有考虑无线传感网络中存在多嵌入不兼容通信设备的问题,一旦网络中存在大量嵌入不兼容传感节点,则这些节点的属性就会偏离普通节点,将会导致无线传感网络通信性能降低。为此,提出考虑多嵌入不兼容设备的无线传感网络路由优化设计方法。在传统的LEACH路由协议的基础上进行优化设计,以传感节点剩余能量作为衡量指标选取合理的节点作为路由节点,并进行均匀布置。在信息传输的过程中,将多跳传输与单跳传输相结合,从而实现了不兼容设备下的路由协议优化。实验结果表明,利用本文算法进行路由协议构建,能够降低网络的能量消耗和信息传输的延时率,提高了通信效率。     

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."     

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.     

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.     

Stern-Gerlach effect goes chiral

Prof. SUN Changpu from the CAS Institute of Theoretical Physics and coworkers from University of Basel in Switzerland have worked out a way --at least in theory --to split a beam of molecules according to their chirality. The technique involves passing the molecules through three different laser beams and is similar to the famous Stern-Gerlach effect, whereby a beam of atoms passing through a magnetic field is split in two according to the atoms＇ spin states （Phys. Rev. Lett. 99 130403）.     

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.