P2P模型在校园网上的应用研究

针对目前流行的P2P网络模型的特点,结合非结构化的P2P网络Gnutella路由和结构化的P2P Pastry路由,提出了一种应用在校园网内的P2P结构模型方案,并给出了详细的P2P节点结构和路由,同时提出了设计该网络模型上的P2P网络应用软件的可行性.     

P2P 架构下环型结构文件热备份系统设计

针对文件共享系统中的文件热备份问题,提出一种在 P2P 网络中利用节点间环型结构实现共享文件备份的方法。围绕环型结构文件热备份设计,在实验系统中同时解决了网络节点加入与退出、节点状态监控、节点连接信息刷新、各节点中共享文件协同检索,以及各节点间实时通信等技术问题。充分利用 P2P 网络结构的技术特点,提高文件共享系统的可用性,同时证明 P2P 网络结构下的文件资源共享系统具有扩展方便、负载变化对系统影响较小等特点。     

Super Node Routing Strategy in Content-Centric Networking

There were two strategies for the data forwarding in the content-centric networking(CCN): forwarding strategy and routing strategy. Forwarding strategy only considered a separated node rather than the whole network performance, and Interest flooding led to the network overhead and redundancy as well. As for routing strategy in CCN, each node was required to run the protocol. It was a waste of routing cost and unfit for large-scale deployment.This paper presents the super node routing strategy in CCN. Some super nodes selected from the peer nodes in CCN were used to receive the routing information from their slave nodes and compute the face-to-path to establish forwarding information base(FIB). Then FIB was sent to slave nodes to control and manage the slave nodes. The theoretical analysis showed that the super node routing strategy possessed robustness and scalability, achieved load balancing,reduced the redundancy and improved the network performance. In three topologies, three experiments were carried out to test the super node routing strategy. Network performance results showed that the proposed strategy had a shorter delay, lower CPU utilization and less redundancy compared with CCN.     

Content subscribing mechanism in P2P streaming based on gamma distribution prediction

P2P systems are categorized into tree-based and mesh-based systems according to their topologies. Mesh-based systems are considered more suitable for large-scale Internet applications, but require optimization on latency issue. This paper proposes a content subscribing mechanism (CSM) to eliminate unnecessary time delays during data relaying. A node can send content data to its neighbors as soon as it receives the data segment. No additional time is taken during the interactive stages prior to data segment transmission of streaming content. CSM consists of three steps. First, every node records its historical segments latency, and adopts gamma distribution, which possesses powerful expression ability, to express latency statistics. Second, a node predicts subscribing success ratio of every neighbor by comparing the gamma distribution parameters of the node and its neighbors before selecting a neighbor node to subscribe a data segment. The above steps would not increase latency as they are executed before the data segments are ready at the neighbor nodes. Finally, the node, which was subscribed to, sends the subscribed data segment to the subscriber immediately when it has the data segment. Experiments show that CSM significantly reduces the content data transmission latency.     

一种高效的P2P系统

目前非结构P2P系统所采用的两层聚类结构HCPON存在的问题是超级节点仅采用单一的备份节点作为冗余备份,使得系统健壮性的提高很有限。由此提出基于三层聚类结构的高效P2P系统（PTLCA）,根据节点的拓扑优先级等对节点进行分层处理和聚类,同HCPON相比,PTLCA在性能上有显著的提高,能够满足大规模流媒体服务的需求。     

基于支持向量回归神经网络的动态系统辨识

结合支持向量机和神经网络各自的优点,提出了一种新颖的自适应支持向量回归神经网络(SVR-NN).首先,利用支持向量回归方法确定SVR-NN的初始结构和初始化权值,基于支持向量自适应地构造SVR-NN神经网络的隐层节点;然后,使用退火过程的鲁棒学习算法更新网络节点参数和权值.为了验证所提出方法的有效性,给出了自适应SVR-NN应用于非线性动态系统辨识的实例.仿真结果表明,与以前的神经网络方法相比,基于SVR-NN网络的辨识方案能获得相当好的性能,它具有很快的收敛速度.因此,自适应的SVR-NN为非线性系统辨识提供了极有吸引力的新途径.     

一种基于DHT的网格动态资源查找算法

P2P与网格都是新型的分布式计算模型,在分析现有网格动态资源发现机制的基础上,将P2P的相关技术引入其中,提出了一种基于DHT的网格动态资源查找算法.该算法结合DHT技术和泛洪式查找技术,在实际的分布式网络之上建立一层结构化的Overlay层.实验结果表明,当用户需要在系统中获取信息时,通过该查找算法,查询只在一些特定的结点上进行,这样就避免了泛洪式查找的盲目性,因此大大提高了信息搜索的效率.     

Hybrid ants-like search algorithms for P2P media streaming distribution in ad hoc networks

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.     

基于二叉树的平面连杆机构运动仿真及软件开发

将平面连杆机构的二副杆、三副杆、机架等构件定义为机构二叉树的结点集合,通过定义构件的联接规则,将机构表示为二叉树数据结构,其中树的节点和左、右孩子包含了连接副和构件几何参数等信息。通过对二叉树的后序遍历算法建立了平面连杆机构运动分析方法,采用面向对象技术开发了平面连杆机构运动仿真软件,实现了平面连杆机构的运动分析与仿真,仿真算例表明了该方法的有效性。     

面向P2P网络的数据库同步系统探讨

P2P数据库同步系统是通过IP进行节点标识定位的,当其他节点发送出来的消息被发送到某节点时,P2P网络中的虚拟身份标识就会绑定到当前IP地址对应的节点上。将P2P技术引入网络数据库领域,能够很好地实现网络数据库系统的高效率、大容量以及协同工作。     

Chord模型分析

Chord是麻省理工学院（MIT）提出的一种基于DHT技术的结构化P2P路由协议,具有完全分布式、负载均衡、可用性及可扩展性好、命名方式灵活等特点,其核心思想就是要解决在P2P应用中遇到的基本问题：如何在P2P网络中找到存有特定数据的节点.     

P2P网络交互式视频点播服务的性能改进

P2P网络交互式视频点播服务中改善用户体验的关键在于减少跳转延时及提高本地缓存的命中率。本文在vEB树基础上增加了跳转到概率较大片段节点的链接,对LRU和LFU算法进行改进提出了基于价值的缓存替换算法。在NS-2环境下进行了模拟实现,实验数据表明改进后的vEB树结构有效地减少节点的跳转延迟,基于价值的缓存替换算法提高了节点片段的命中率。     

KRBKSS： a keyword relationship based keyword-set search system for peer-to-peer networks

Distributed inverted index technology is used in many peer-to-peer (P2P) systems to help find rapidly document in -set search system for peer-to-peer networkswhich a given word appears. Distributed inverted index by keywords may incur significant bandwidth for executing more complicated search queries such as multiple-attribute queries. In order to reduce query overhead, KSS (keyword-set search) by Gnawali partitions the index by a set of keywords. However, a KSS index is considerably larger than a standard inverted index,since there are more word sets than there are individual words. And the insert overhead and storage overhead are obviously unacceptable for full-text search on a collection of documents even if KSS uses the distance window technology. In this paper, we extract the relationship information between query keywords from websites' queries logs to improve performance of KSS system.Experiments results clearly demonstrated that the improved keyword-set search system based on keywords relationship (KRBKSS) is more efficient than KSS index in insert overhead and storage overhead, and a standard inverted index in terms of communication costs for query.     

Resources publication and discovery in manufacturing grid

INTRODUCTION Manufacturing Grid (MGrid) is a new concept proposed to meet the practical demands in the manufacturing industry and is a new technology enabling broad geographical distribution of all sorts of manufacturing resources through the Internet or other specific nets, using grid technology. With the MGrid platform, we can realize common sharing of manufacturing resources including human resources, equipment resources, material resources, applicable software systems, etc., and can …     

Multiple description coding with spatial-temporal hybrid interpolation for video streaming in peer-to-peer networks

INTRODUCTION Multimedia services over the Internet are be- coming popular due to the widespread deployment of broadband access. However, the conventional cli- ent-server architecture severely limits the number of simultaneous users, especially for bandwidth inten- sive applications such as video streaming. P2P net- works, on the other hand, offer a solution to the scalability problem. As a node joins a P2P network, it not only consumes resources but also contributes its bandwidth or comp…     

基于关系数据库表树的数据结构研究

随着关系数据库技术的应用越来越广泛,利用关系表格、关系代数、结构化查询语言等研究基于外存储结构的数据结构有着实际的意义。本文从一个具有树结构的学校管理模型出发,提出一种用关系数据库表来表示树的方法,讨论了如何利用关系代数和SQL语言对表格进行一般查询,借助JaVa语言实现二叉树中比较典型的前序、中序和后序算法,最后对文章开始引出的问题给出了实现程序。     

DS-BPSO算法在P2P邻接选择问题中的研究

节点选择机制是P2P网络的研究热点与核心技术,近年来得到广泛的关注.该文将一种改进的粒子群优化算法-具有双重结构编码的二进制粒子群优化算法（DS-BPSO）应用于P2P文件共享系统的邻居节点选择过程.在动态性方面,粒子群优化算法（PSO）与P2P网络具有先天的相似性.每个粒子（节点）通过有向图来编码与其它粒子的连接矩阵,更符合ADSL连接常规.实验结果表明：对于大规模的邻接选择问题,DS-BPSO算法通常会比二进制粒子群优化算法（BPSO）能够查找到更好的邻居节点.     

Study on semantic-oriented hybrid indexing strategy of resource metadata in peer-to-peer network

INTRODUCTION In some large scale corporations and virtual or-ganization environment (education system, military organizations, etc.), much electronics information resources are distributed physically and diverse in types. Each unit of an organization manages some resources respectively, according to the domain knowledge or the particular mission. In technical aspect, each unit is a node working independently in the information network. These nodes can join or leave the network at any tim…     

Rate-distortion optimized bitstream switching for peer-to-peer live streaming

Peer-to-peer （P2P） technology provides a cost-effective and scalable way to distribute video data. However, high heterogeneity of the P2P network, which rises not only from heterogeneous link capacity between peers but also from dynamic variation of available bandwidth, brings forward great challenge to video streaming. To attack this problem, an adaptive scheme based on rate-distortion optimization （RDO） is proposed in this paper. While low complexity RDO based frame dropping is exploited to shape bitrate into available bandwidth in peers, the streamed bitstream is dynamically switched among multiple available versions in an RDO way by the streaming server. Simulation results show that the proposed scheme based on RDO achieves great gain in overall perceived quality over simple heuristic schemes.     

Comparison of Attribute Reduction Methods for Coronary Heart Disease Data by Decision Tree Classification

Attribute reduction is necessary in decision making system. Selecting right attribute reduction method is more important. This paper studies the reduction effects of principal components analysis （PCA） and system reconstruction analysis , SRA） on coronary heart disease data. The data set contains 1723 records, and 71 attributes in each record. PCA and SRA are used to reduce attributes number （less than 71 ） in the data set. And then decision tree algorithms. C4.5, classification and regression tree （ CART）, and chi-square automatic interaction detector （ CHAID ）, are adopted to analyze the raw data and attribute reduced data. The parameters of decision tree algorithms, including internal node number, maximum tree depth, leaves number, and correction rate are analyzed. The result indicates that. PCA and SRA data can complete attribute reduction work. and the decision-making rate on the reduced data is quicker than that on the raw data： the reduction effect of PCA is better than that of SRA. while the attribute assertion of SRA is better than that of PCA. PCA and SRA methods exhibit good performance in selecting and reducing attributes.