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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。 相似文献
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网络病毒感染的免疫性分析是提高网络安全性能的重要因素。由于网络病毒具有发散指向性,导致对网络病毒的感染免疫性分析建模困难。提出基于多频自适应共振检测的网络病毒感染免疫性分析模型,构建多路复用器输入输出的网络病毒感染模型,进行病毒信息特征预处理,得到用户约束对照多路复用状态下的病毒入侵干扰链路结构。根据自相关函数极限分离定理,在极向环空间内进行自相关成分分析,以代价函数最小化的形式进行病毒感染强度快速寻优分离,由此实现对病毒感染的免疫性分析模型构建。通过仿真实验结果表明,采用该算法,对网络在遭受病毒感染下的免疫控制性能较平稳,代价开销控制精度合理,网络波动被约束到了一个较小的范围,展示了方法优越的病毒感染限定和免疫性能。 相似文献
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移动网络基站的信道分配具有动态性,在信道切换中需要考虑基站节点的安全承载问题。研究移动网络基站安全承载信道分配重构算法对提高移动通信组网的可靠性具有重要意义。传统算法设计多跳基站接入模式,难以满足用户需求。提出一种基于信道切换队列的动态信道分配算法,设计移动网络基站的安全承载模型,得到移动网络基站节点服务与构件之间、业务与服务之间存在如下映射关系。实现信道分配的安全承载重构。定义可重构移动通信网络的安全负载强度,确定不同安全等级需要基站部署节点位置向量,对所有信道进行实时分配,实现了移动网络基站安全承载信道分配重构算法改进。仿真结果表明,该算法能有效提高通信网络的负载率,信道重构在增加网络节点平均负载率的情况下可降低网络节点最大负载率,从而使得网络负载均衡,提高通信的安全性和稳定性。 相似文献
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在基于802.16j的无线中继网络中,考虑路由和调度的联合优化问题,最小化系统总调度时间. 首先采用线性规划的方法建立路由,进行链路业务速率分配,然后基于平移和交换思想提出一种链路调度算法. 理论分析证明所提算法的性能在最坏情况下,不会超过最优性能的1.5倍. 仿真结果表明,所提算法的平均性能非常接近最优性能. 相似文献
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为了保证无线传感网络中任务节点负载的水平相当,延长网络的生命周期,需要对物联网环境下任务节点负载动态非对称分配系统进行设计。为此,提出一种基于单片机的任务节点负载动态非对称分配系统设计方法。该方法首先对任务节点负载动态非对称分配系统硬件进行设计,硬件部分主要由微处理器、节点电压的采样电路、节点电流的采样电路、节点传输的模块以及电路模块和节点通信模块构成。软件部分利用节点分配算法对任务节点负载动态非对称分配进行计算,结合硬件与软件部分设计完成对物联网环境下任务节点负载动态非对称分配系统设计。实验结果表明,该方法能有效地解决节点负载动态非对称分配不均衡的问题,提高了无线传感网络的生命周期。 相似文献
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为了克服传统分簇路由协议中无法有效缓解"热区"和数据传输可靠性不高的问题,设计一种基于并行SOM和自适应禁忌优化算法的负载均衡路由协议。首先,将整个网络区域分为若干子区域,在每个子区域中自适应的根据节点与基站的距离确定分簇数目,采用并行SOM并行对网络区域进行分簇,同时根据能量和位置因素选举簇头;然后,以最小化各簇头到基站的最小跳数为目标,采用改进的禁忌优化算法来寻找各簇头到达基站的最优解和次优解,构成多条冗余路由,以增强数据传输的可靠性,最后,对基于改进禁忌优化算法的最小跳数路由协议进行了设计和描述。仿真实验表明:文中方法能有效地提高网络生命周期和提高数据传输的可靠性,具有很好的负载均衡能力,是一种适用于WSN的有效分簇路由算法。 相似文献
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由于无线网路中链路质量的不稳定、信号的广播传输模式和节点之间存在的相互干扰，针对提高无线网状网络性能的信道分配和路由选择将更加复杂。采用多信道成为一种可选的提高网络容量的方法。本文提出了一种基于2.4GHz 802.11无线网状网络的一种固定信道分配方法，采用了多输入多输出技术使得网络中的数据流以流水线的方式进行传输。在这个场景下多条并行的流可以同时被激活，以此来提升UDP和TCP的传输性能。通过对802.11b网络中1、6和11三个相互不重叠的信道的分配，该信道分配算法在空间上实现邻居节点之间的干扰最小化，其中信道1和11被分配给网状网络的主干传输部分，信道6被分配给用户接入网络。文章最后通过NS2仿真实验，并对本文提出的算法进行了分析。实验结果证明网络的平均吞吐率有大幅度提升，且多跳传输的延迟也被降低。 相似文献
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《科技通报》2015,(8)
传统方法使用量子群遗传进化方法进行云存储系统任务调度的执行开销建模,在数据汇聚和协议传输中没有考虑量子态的相干性和感知节点的方向性,不能全局搜索最优量子位,执行开销不能实现最小化。提出一种基于量子群聚类的云存储调度最小执行开销建模算法,首先进行量子群聚类进化策略和云存储系统任务调度模型总体设计,设计基于量子群聚类的云存储系统任务调度分配协议,进行有效的资源调度设计,整合云计算中心资源,提高资源利用率,减少任务执行时间。仿真结果得出,该算法能使云存储系统任务调度执行开销与任务规模的匹配性能最佳,性能优于传统算法,在云存储信息管理系统等领域具有较好的应用价值。 相似文献
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A research 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 in red wine-can improve the sensitivity of mice to the hormone insulin according to a report in the October issue of Cell Metabolism.…… 《中国科学院院刊(英文版)》2008,22(1):14-15
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. 相似文献
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Marjorie Armstrong-Stassen Margaret Landstrom Ramona Lumpkin 《The Information Society》1998,14(2):153-164
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. 相似文献
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A joint study by Prof. ZHANG Zhibin from the CAS Institute of Zoology his co-workers from Norway US 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 the National Academy of Sciences on September .…… 《中国科学院院刊(英文版)》2008,22(1):6-7
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. 相似文献
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Caroline Haythornthwaite 《The Information Society》2001,17(3):211-226
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. 相似文献
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Active biological molecules 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 therapy new nanodevice construction.…… 《中国科学院院刊(英文版)》2008,22(1):22-22
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. 相似文献
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《中国科学院院刊(英文版)》2008,22(1):2-3
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. 相似文献
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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. 相似文献
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《中国科学院院刊(英文版)》2008,22(1)
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." 相似文献
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Puay Tang 《The Information Society》1998,14(1):19-31
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. 相似文献
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Leah A. Lievrouw 《The Information Society》2000,16(2):155-159
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. 相似文献