网络数据库中的高效检索节点图设计与分析

提出基于有向图模型设计的网络数据库高效检索节点分布设计方法。首先构建网络数据库检索节点的分布模型,分析数据结构,对检索节点的存储数据语义特征进行信息融合处理;然后采用有向图模型分析方法检索网络数据库节点属性聚类和自适应调度,实现数据库的高效检索节点有向图模型设计;最后设计仿真实验进行性能测试,实验结果表明,该方法有效提高了网络数据库的检索效率,尤其对超大规模数据库检索的执行效率更高。     

数据库复杂网络构造算法及特征分析

数据库复杂网络是对管理信息系统软件复杂性的一种度量,提供了一种精简的可视化业务逻辑描述,为软件增量设计提供了自说明文档。为抽取数据库复杂网络,提出了两种算法:(1)基于数据表主外键关联的网络构造算法;(2)基于隐性语义关联的构造算法及扩展算法。通过对9个软件数据库的分析,研究了该类网络的统计特性,发现其无标度特性入度分布比出度分布更不均匀,入度大的节点是系统的骨干节点。为精准构造直接辅助软件工程的数据库复杂网络,提出了针对语义隐性关联的一组命名规范。     

P2P直播系统在SDN的部署研究

提出一种在SDN部署P2P直播系统的方案,即OpenP2P,OpenP2P利用SDN控制器收集全局网络视图,在构造P2P覆盖网络时充分考虑Peer节点的物理位置、负载状况等信息,从而构建高效的P2P逻辑网络。当Peer节点交换直播数据时,控制器可以实时探测网络状态,动态调整数据传输路径,以实现网络链路最优化利用。仿真结果表明,使用OpenP2P传输直播数据能够大大减少带宽消耗并降低传输时延。     

电力数据信息网络阻塞故障节点快速辨识研究

由于电力数据信息网络阻塞,导致脆弱性故障节点快速扩散,造成故障节点辨识效果差且耗时较长。为此,提出了电力数据信息网络阻塞故障节点快速辨识研究。构建网络阻塞故障节点跟踪模型,获取故障节点跟踪集合。使用层次分析法构造比较矩阵,计算辨识指标权重向量。定量分析故障数据特征,获取故障节点信息特征矢量。结合神经网络模型构建分析矩阵,在短时间内得到最终故障节点分布结果。通过量化指标,获取故障节点辨识结果。计算节点继电保护脆弱贡献度,辨识脆弱故障节点。由实验结果可知,该方法统计的故障节点信息特征与理想特征一致,具有较好的辨识效果,辨识时间仅为10 s,加快了故障节点的辨识速率。     

一种基于适应度和节点聚类的P2P拓扑建模方法

 通过对Gnutella网络拓扑实测数据的分析,得到了Gnutella网络的累积节点度分布、聚类系数、平均路径长度和rich-club系数等拓扑特征。在拓扑特征分析的基础上,通过引入适应度、邻居数限制和节点聚类等机制,提出了面向非结构化P2P网络拓扑的FCL(Fitness model with tunable Clustering and neighbours Limitation)模型,并给出了建模算法。通过实验分析,证明了该模型的有效性。     

一种新型的基于节点类型识别机制的P2P网络拓扑构造协议

现有P2P网络拓扑构造协议大多是基于节点历史行为来决定拓扑的构造方式,在面对P2P节点复杂多变的行为时无法实时地保证拓扑的有效性。该文首先利用博弈论针对不同类型节点的交互行为及收益建立博弈模型。在此基础上,提出了基于节点类型跟踪识别机制的拓扑构造协议TATP。仿真实验表明,TATP协议即使在恶劣的P2P网络环境下也能够让善意节点开始聚集,将恶意节点排斥到网络边缘,使得P2P网络拓扑具有更好的有效性和安全性,同时协议的网络开销较小。     

无线传感器网络LEACH协议的改进与仿真

LEACH路由协议是无线传感器网络中经典的层次型拓扑组织算法。对LEACH协议进行研究和分析,指出LEACH协议在簇的区域分布和簇头负载不均衡等方面问题。文章通过节点剩余能量和与基站的距离对簇头选择、构造分簇以及非簇节点选择簇头进行改进。并利用MATLAB对改进后的算法进行仿真,表明改进后的算法有效地均衡节点能量消耗,并延长网络生存时间。     

无线传感器网络LEACH协议的改进与仿真

LEACH路由协议是无线传感器网络中经典的层次型拓扑组织算法。对LEACH协议进行研究和分析,指出LEACH协议在簇的区域分布和簇头负载不均衡等方面问题。文章通过节点剩余能量和与基站的距离对簇头选择、构造分簇以及非簇节点选择簇头进行改进。并利用MATLAB对改进后的算法进行仿真,表明改进后的算法有效地均衡节点能量消耗,并延长网络生存时间。     

利用复杂网络分析导航台网络结构鲁棒性

针对导航台网络频繁遭受突发事件影响的情况,构建了以导航设备覆盖的航路结构为基础的网络模型,提出一套完善的设备网络鲁棒性研究指标集,从网络结构角度对导航台设备网络进行鲁棒性分析。以西南地区为例:导航台网络对随机攻击鲁棒性最高,网络是无标度网络;攻击数目在5-13个节点时,节点介数攻击导致网络效率降低最快,对网络连通性破坏最大。融合相邻导航台节点贡献作用,导航台节点鲁棒性评估值近似服从幂律分布。     

基于CC2510的无线自组织传感器网络构建

无线传感器网络是由部署在监测区域内大量的廉价微型传感器节点组成,通过无线通信方式形成的一个网络系统。考虑到体积和节能等因素,对于很多应用场合来说,传感器的发射功率不可能很大。为了保证传感器节点间协作,提高网络的吞吐量,改善网络的性能;采用了CC2510芯片来构建无线自组织传感器网络的方法,实验结果表明,自组织网络具有无中心、自组织、多跳路由、动态拓扑等区别于普通网络的特性,提高了网络的整体效用。     

基于成本与网络负载最优的智能配电通信网络规划策略

针对配电网络单个通信终端节点数据量小、通信终端节点多的特点,在提高网络接入节点数量的基础上最大化网络的负载.在宏基站、微基站部署方式上,将宏基站与微基站同时部署,以提供给微基站更多的部署选择.在分析智能配电网络通信业务需求、现有网络规划的弊端的基础上,建立了多目标优化模型,并与单目标优化模型进行对比分析.最后,从规划方案图以及网络性能分析上证明了本文所提策略的优越性.     

Online social network model with renewal and accelerated growth

Based on observation of the growing mechanism in Twitter-like online social networks, an online social network （OSN） evolution model was proposed, a renewal mechanism for the old nodes and an accelerated growth mechanism was introduced for the new nodes, comparing with the native copying model. Topological characteristics of the generated networks, such as degree distribution, average shortest-path length and clustering coefficient, are analyzed and numerized. These properties are validated with some crawled datasets of real online social networks.     

天基信息网络的软件定义网络应用探析

现有各种空间、地面网络节点的互连互通,在一定程度上可满足特定应用需求,但由于各节点在空间、物理以及功能的局限,限制了天基信息高效传输、融合以及按需地应用。分析了天基信息网络的发展趋势,提出了网络架构构想,并对主要关键技术的研究方向进行了梳理。在空间核心节点上采用软件定义的多功能载荷平台,并基于软件定义网络( SDN)架构和空间容中断网络协议构建天基信息网络。通过资源虚拟化、处理多元化、应用无阻化的方式,保障天基信息网络适应信息按需定制和高效共享等应用需求。     

基于几何学的无线传感器网络定位算法

提出一种基于几何学的无线传感器网络(WSN)定位算法。把网络区域中的节点分为锚节点和未知节点,假设在定位空间中有n个锚节点,由于受到几何学的限制,实际可行的锚节点序列是有限的,因此利用一种几何方法判断锚节点间的位置关系,从而选取最优的锚节点序列,能够更精确地确定未知节点的位置,并且分析了待定位节点的邻居锚节点数量对定位精度的影响。仿真结果表明,与已有的APS(Ad-Hoc positioning system)定位算法相比,该算法可有效地降低平均定位误差和提高定位覆盖度。     

基于信道切换的车联网数据传输算法

提出一种基于信道切换的车联网数据传输算法（DTA）。DTA算法考虑由车辆节点、中继节点和汇聚节点组成的三层网络,根据车辆的行驶方向进行节点的分类,提出不同的信道分配和切换机制,减少了数据传输的干扰。提出中继节点信息的快速扩散方法。提出紧急路况信息的优先传输方法,采用不同的队列将数据分类,并根据队列优先级选择传输数据。仿真结果表明,DTA算法能够有效地实现有用信息的快速传输,减少不必要的损耗,提高汇聚节点数据接收率,降低数据分组平均跳数和提高数据传输的覆盖率。在一定的条件下,DTA算法比AODV算法和AODV-L算法更优,可适用于快速变化的车辆行驶环境。     

A novel residual energy‐based distributed clustering and routing approach for performance study of wireless sensor network

Non‐uniform energy consumption during operation of a cluster‐based routing protocol for large‐scale wireless sensor networks (WSN) is major area of concern. Unbalanced energy consumption in the wireless network results in early node death and reduces the network lifetime. This is because nodes near the sink are overloaded in terms of data traffic compared with the far away nodes resulting in node deaths. In this work, a novel residual energy–based distributed clustering and routing (REDCR) protocol has been proposed, which allows multi‐hop communication based on cuckoo‐search (CS) algorithm and low‐energy adaptive‐clustering–hierarchy (LEACH) protocol. LEACH protocol allows choice of possible cluster heads by rotation at every round of data transmission by a newly developed objective function based on residual energy of the nodes. The information about the location and energy of the nodes is forwarded to the sink node where CS algorithm is implemented to choose optimal number of cluster heads and their positions in the network. This approach helps in uniform distribution of the cluster heads throughout the network and enhances the network stability. Several case studies have been performed by varying the position of the base stations and by changing the number of nodes in the area of application. The proposed REDCR protocol shows significant improvement by an average of 15% for network throughput, 25% for network scalability, 30% for network stability, 33% for residual energy conservation, and 60% for network lifetime proving this approach to be more acceptable one in near future.     

Visualization of Ethereum P2P network topology and peer properties

Ethereum is arguably the second most popular cryptocurrency-based network after Bitcoin. Both use the distributed ledger technology known as the blockchain, which is considered secure. However, the provided security level is proportional to the number of connected nodes, the number of influential nodes, and the supported amount of hash power. Thus, the knowledge of the network properties and nodes' behavior is helpful to protect the network from possible attacks such as double-spending attacks, DDoS attacks, 51% attacks, and Sybil attacks. This paper proposes a node discovery mechanism, which performs a P2P link discovery on the Ethereum main network. For that, we develop Search-node, a modified version of Ethereum client that searches for all participating nodes in the blockchain network, stores the node information in the Bucket, and then processes the peer discovery method. Based on the collected data, we first visualize the Ethereum network topology and analyze the attributes of the network such as node degree, path length, diameter, and clustering coefficient. We then analyze the node properties and provide analytical results regarding the relationship between nodes, heavily connected nodes, node geo-distribution, security issues, and possible attacks over the influential nodes. As a result, we have identified 68,406 nodes with a total of 642,034 edges. By analyzing the collected data, we have found that the diameter in the Ethereum network is equal to 8. The node degree is over 19, which is two times higher than the default configuration.     

基于ZigBee无线网络的可控组网方法研究

ZigBee无线网络中节点多采用自组网的方式入网,这种方式容易引起网络中部分节点的过度消耗。针对此种情况提出可控组网方式,通过对节点入网父节点的选择控制,可以有效的监控管理整个网络的拓扑结构和节．最分布,并延长节点和网络的寿命。通过在基于CC2530的开发系统中对可控组网方式编译和实现,验证了其可行性。     

On the Geometrical Characteristic of Wireless Ad-Hoc Networks and its Application in Network Performance Analysis

A wireless ad-hoc network can be roughly considered as one consisting of a collection of mobile nodes distributed in a finite region, which adopts a non-centralized and self-organized structure. In such networks, messages are transmitted, received and forwarded in a finite geometrical region. In addition, the transmission of messages is highly dependent on the locations of the mobile nodes. As a result, the geometrical relationships between the nodes, and especially the distance between them are of fundamental importance. In this paper, we propose a space decomposition method to analyze the probability distribution of the distance between nodes in an ad-hoc network. In particular, we derive two theoretical expressions for the probability distribution of the distance between nodes under the assumption that the nodes are independently and uniformly distributed in either a rectangular region or hexagonal region. Further results on the node degree distribution and max-flow capacity of the network are then presented based upon these expressions     

信任感知的安全虚拟网络映射算法

针对网络虚拟化技术带来的新的安全威胁,将信任关系和信任度引入到虚拟网络资源分配中,量化分析了网络虚拟化环境中的安全问题,构建了安全虚拟网络映射的数学模型,并在映射过程中考虑节点的局部和全局重要性,采用逼近理想排序法方法对节点进行多属性重要度排序,提出了一种信任感知的安全虚拟网络映射算法。仿真结果表明,该算法在满足虚拟网络请求可信需求的条件下,获得了较好的映射成功率、映射收益和资源利用率。