共查询到19条相似文献，搜索用时 171 毫秒
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点对点网络（P2P）指网络用户之间可以直接通信的网络结构。P2P使用户可以直接连接其他用户的计算机,而不是像过去那样连接到服务器去浏览和下载。介绍BitTorrent在P2P网络中的作用,对BitTorrent系统中涉及的torrent文件格式、节点与tracker之间的通信协议以及节点之间的通信协议进行分析。 相似文献
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韩亚峰 《河南职业技术师范学院学报(职业教育版)》2013,(1):86-90
数据调度算法是P2P研究的热点问题.算法性能的优劣会直接影响到P2P系统的服务质量.通过分析P2P流媒体直播系统中节点能力和数据分片的优先级,提出了最少最小优先调度算法(LRFA).算法结合了现有的最少优先策略,将数据的稀缺性和时间特性作为重要因素,对节点能力进行了动态估算,最终实现了节点资源的充分利用. 相似文献
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在大规模桌面虚拟化集群部署过程中,虚拟机镜像创建时,大量镜像数据在镜像服务器和计算节点服务器之间传输,下载速度直接影响着虚拟桌面的创建和更新速度。为了提高虚拟机镜像模板部署和系统的整体性能,从网络传输角度,提出一种基于BitTorrent的P2P技术提升镜像下载速度的方法。该方法在计算节点数量较多的情况下,能大幅提高镜像下载速度,从而保证镜像模板的快速分发,提升用户对桌面虚拟化系统的使用体验。 相似文献
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研究了P2P直播系统网络模型,并在此基础上提出一种基于可信节点的半结构化的网络模型(SSPM)。该模型结合了结构化网络模型中的对相邻节点有序组织和混合式网络模型的快速搜索的优点,利用可信节点良好的时间恒定性和性能稳定性,使该新型模型在实际网络环境下能达到较优的性能。 相似文献
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在P2P流媒体系统中,一个高效实用的资源索引及传输机制能很好地均衡系统的负载,加强系统的稳定性,并减少节点的搜索时延.在实际的应用中,不同服务能力的节点对于整个网络的不同贡献应该得到不同的激励.本文提出一种具有商业激励的P2P流媒体系统资源索引及传输机制.文章在对节点进行空间划分的基础上,对现有的节点良好度评价标准,节点排序算法做出了改进,并在相应的商业激励值下进行数据的传输.该机制加快了资源的搜索速度,均衡了系统负载并提高了用户上传的积极性,对于现有P2P流媒体系统的改进具有积极的意义. 相似文献
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本文在研究P2P网络传输模式和多媒体技术的基础上,详细介绍了如何利用这些技术对校园网络课堂教学系统进行设计与实现,以此发挥校园网络节点资源,提高课堂教学实时交互,增强现场教学效果,并为高校教育信息化的实施提供一定的借鉴和指导作用. 相似文献
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本文通过分析研究CAN(Content-Addressable Network)语义路由算法,改进源节点到目的节点语义路由中继节点序列,从建立相应的P2P网络节点物理位置参照系入手,依据节点坐标间的相对距离,来自局部节点的物理邻居信息及最短路径,对O-CAN路由性能进行理论分析及推导。OCAN算法既不修改原有P2P网络的nodeid的值,也不在网络中设置超级节点,在提高路由效率的同时,保证了网络节点的对等性。 相似文献
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P2P网络的逻辑结构和物理结构匹配,主要是指对节点的物理网络位置的知晓（比如距离的远近）,以及逻辑层与物理层之间的拓扑网络结构的匹配。资源搜索是P2P网络中非常重要的构成部分,但是同时也带来了很大的网络开销,此外,资源搜索过程中查询消息需要在逻辑层的网络拓扑网络中传输,这就引出了逻辑层与物理网络层之间的匹配问题。 相似文献
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TaChord:利用拓扑相关路由算法和超级节点的Chord系统 总被引：7，自引：0，他引：7
由于未考虑实际网络拓扑结构,当前结构化对等网络系统存在高延迟低效率的毛病. 本文提出一种与实际网络拓扑结构相关的路由方法,并开发出一种基于Chord的TaChord系统. 在仿真系统中, 用物理跳数、域间延迟和每个消息占用的带宽来衡量TaChord和其他系统的路由性能. 仿真结果表明,TaChord系统的路由性能有了极大的提高, 如平均物理跳数是Chord的一半,并且不同路由缓存管理策略对TaChord的路由性能能产生重要的影响. 相似文献
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ZUO Dong-hong DU Xu YANG Zong-kai 《浙江大学学报(A卷英文版)》2007,8(8):1191-1198
Media streaming delivery in wireless ad hoc networks is challenging due to the stringent resource restrictions,po-tential high loss rate and the decentralized architecture. To support long and high-quality streams,one viable approach is that a media stream is partitioned into segments,and then the segments are replicated in a network and served in a peer-to-peer(P2P) fashion. However,the searching strategy for segments is one key problem with the approach. This paper proposes a hybrid ants-like search algorithm(HASA) for P2P media streaming distribution in ad hoc networks. It takes the advantages of random walks and ants-like algorithms for searching in unstructured P2P networks,such as low transmitting latency,less jitter times,and low unnecessary traffic. We quantify the performance of our scheme in terms of response time,jitter times,and network messages for media streaming distribution. Simulation results showed that it can effectively improve the search efficiency for P2P media streaming distribution in ad hoc networks. 相似文献
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In the UK, the creative sector has been identified as a key strand in the economic recovery strategy. Composed of mostly micro and small enterprises often grouping together for particular commissions and projects, there is a tendency to operate primarily through a series of networks made up of peers. This paper presents the outcomes of a ‘peer-to-peer business programme’, or action learning set, involving 10 participants from the creative sector over a period of 6 months. The programme was based on a ‘Six-Squared’ model where participants would address their own needs alongside participating in, and developing further understanding of, action learning sets in order to establish sets with others. Assessment of outcomes indicated that the programme allowed participants to develop new skills with peers, network and strengthen relationships and collaborate in a university programme. The paper concludes by suggesting that, within the context of a growing and vibrant creative industries sector and increasing pressures on universities to engage with the business community, it is essential to develop flexible, peer-led and innovative models of collaboration. 相似文献
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基于语义叠加网的对等网搜索机制 总被引：1，自引：0，他引：1
针对目前超结点叠加网络研究中的不足,将语义信息引入到超节点的组织过程中,提出了一种新的对等网搜索模型———SSP2P.模型中结点依据小世界理论在物理上形成自然的区域自治系统(AAS),各AAS依据幂规律选取各域内的超结点,超结点再根据语义关系形成多个超结点语义网(SSN),从而形成一个层次化的超结点叠加网络模型.实验结果表明:该模型在保证系统扩展性的基础上有效地提高了搜索效率,减少了通信开销.证明在超节点叠加网络的构建过程中语义信息的引入有利于对等网搜索性能的提高. 相似文献
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一种支持分类数据源查找的语义覆盖网络 总被引：1，自引：0，他引：1
针对使用分类层次来描述数据语义的分布式数据源,提出了一种支持数据共享的基于super-peer的语义覆盖网络SSON.SSON能够根据数据的语义,动态地将peer划分成多个语义簇,语义簇之间组织成语义覆盖网络.每个语义簇由一个super-peer和一组peer组成,仅负责回答其语义子空间上的查询.查询首先根据其语义被路由到适合的语义簇中,然后被转发给包含结果的peer.同时给出了相关的算法,并进行了实验研究,实验结果表明,SSON具有良好的可扩展性,并在查找性能和代价之间取得了一个良好的折中. 相似文献
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We used data gathered via investigative “RoundUp” software to measure a year of online child pornography (CP) trafficking activity by U.S. computers on the Gnutella peer-to-peer network. The data include millions of observations of Internet Protocol addresses sharing known CP files, identified as such in previous law enforcement investigations. We found that 244,920 U.S. computers shared 120,418 unique known CP files on Gnutella during the study year. More than 80% of these computers shared fewer than 10 such files during the study year or shared files for fewer than 10 days. However, less than 1% of computers (n = 915) made high annual contributions to the number of known CP files available on the network (100 or more files). If law enforcement arrested the operators of these high-contribution computers and took their files offline, the number of distinct known CP files available in the P2P network could be reduced by as much as 30%. Our findings indicate widespread low level CP trafficking by U.S. computers in one peer-to-peer network, while a small percentage of computers made high contributions to the problem. However, our measures were not comprehensive and should be considered lower bounds estimates. Nonetheless, our findings show that data can be systematically gathered and analyzed to develop an empirical grasp of the scope and characteristics of CP trafficking on peer-to-peer networks. Such measurements can be used to combat the problem. Further, investigative software tools can be used strategically to help law enforcement prioritize investigations. 相似文献
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We provide detailed measurement of the illegal trade in child exploitation material (CEM, also known as child pornography) from mid-2011 through 2014 on five popular peer-to-peer (P2P) file sharing networks. We characterize several observations: counts of peers trafficking in CEM; the proportion of arrested traffickers that were identified during the investigation as committing contact sexual offenses against children; trends in the trafficking of sexual images of sadistic acts and infants or toddlers; the relationship between such content and contact offenders; and survival rates of CEM. In the 5 P2P networks we examined, we estimate there were recently about 840,000 unique installations per month of P2P programs sharing CEM worldwide. We estimate that about 3 in 10,000 Internet users worldwide were sharing CEM in a given month; rates vary per country. We found an overall month-to-month decline in trafficking of CEM during our study. By surveying law enforcement we determined that 9.5% of persons arrested for P2P-based CEM trafficking on the studied networks were identified during the investigation as having sexually offended against children offline. Rates per network varied, ranging from 8% of arrests for CEM trafficking on Gnutella to 21% on BitTorrent. Within BitTorrent, where law enforcement applied their own measure of content severity, the rate of contact offenses among peers sharing the most-severe CEM (29%) was higher than those sharing the least-severe CEM (15%). Although the persistence of CEM on the networks varied, it generally survived for long periods of time; e.g., BitTorrent CEM had a survival rate near 100%. 相似文献
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In England teachers of secondary school mathematics and science are in short supply and it is important to understand how pre-service teachers develop and maintain networks of support during their training year and the impact these networks can have on their training outcomes. The purpose of this study is to examine how changes to the size and composition of these support networks during the training year are associated with programme outcomes. The paper draws on social network theory to examine the nature of the support networks that develop around each pre-service teacher, and examines how supportive ties were initiated, maintained, and broken over the course of the training year. A survey design was utilised to collect data at four time points across the 2014–2015 academic year from a total cohort of more than 75 pre-service teachers. At all four time points, participants were asked to nominate those peers and others to whom they had turned during the previous month for different aspects of support. Results showed that the size and composition of support networks changed over time with significant differences in the development of the networks between pre-service teachers on school-led and university-led programmes. 相似文献
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Sophina Choudry Julian Williams Laura Black 《British Journal of Sociology of Education》2017,38(7):1037-1053
The aim of this article is to explore the structure of social capital in peer networks and its relation to the unequal access of educational resources within mathematics classrooms. We hypothesise that learners can gain access to mathematics through friendship networks which provide more or less help from peers that might sustain (or curtail) their mathematics learning based on a Bourdieusian framework. We report a social network analysis of mutually-recognised helping within friendship groups. This is complemented by observation and interviews that illustrate how different classrooms have different network structures, positioning learners of different ethnic minorities and genders in significantly different ways regarding access to learning. We argue that friendship networks mediate social capital and access to further cultural capital, and that this may help explain structural differences in attainment. Because ethnicity and gender, inter alia, mediate friendship networks, they also mediate access to capital in the classroom. 相似文献