软件宏观拓扑结构标准结构熵和度的演化分析

现代软件生存周期可以看做是一个软件结构的演化过程.基于大量开源软件的统计数据,分析了标准结构熵、高度值节点数量和新增节点中低度值节点所占比例的演化,然后分析了度中心化指标较高的节点数量和新增节点中该指标较高的节点数量的演化.结果表明,标准结构熵和度中心化指标较高的节点数量普遍呈下降趋势,高度值节点数量呈上升趋势,新增节点大都为低度值节点.由此得出,成功实践的软件演化过程中,软件网络和软件结构的复杂性增长速度是逐步降低的.本研究对于指导软件开发有重要的作用.     

Disentangling nestedness from models of ecological complexity

Complex networks of interactions are ubiquitous and are particularly important in ecological communities, in which large numbers of species exhibit negative (for example, competition or predation) and positive (for example, mutualism) interactions with one another. Nestedness in mutualistic ecological networks is the tendency for ecological specialists to interact with a subset of species that also interact with more generalist species. Recent mathematical and computational analysis has suggested that such nestedness increases species richness. By examining previous results and applying computational approaches to 59 empirical data sets representing mutualistic plant–pollinator networks, we show that this statement is incorrect. A simpler metric—the number of mutualistic partners a species has—is a much better predictor of individual species survival and hence, community persistence. Nestedness is, at best, a secondary covariate rather than a causative factor for biodiversity in mutualistic communities. Analysis of complex networks should be accompanied by analysis of simpler, underpinning mechanisms that drive multiple higher-order network properties.     

一种通信网络节点重要性的计算公式

针对基于节点的移除可能导致网络拓扑结构变化的不足,提出了一种确定通信网络节点重要性的评价公式.该公式综合考虑了节点在网络中的全局性影响,能精确地评价网络节点重要性,尤其对解决卫星网络的节点重要性评价方面.该计算公式定义了网络中节点重要性取决于该节点在网络中的位置信息和其他节点对该节点的贡献度.节点的位置由节点介数确定,其他节点对该节点的贡献度与其他节点的介数及紧密度相关.利用该公式对典型网络的节点重要性进行分析,并与其他评价方法进行对比,结果表明,该公式能精确并正确评价节点对网络的控制能力.     

大型设备监测用新型无线传感器网络

针对工业环境大型设备的状态监测,对无线传感器网络节点及网络结构进行优化.将网络节点分为3个级别,并分别进行能耗及功能设计,综合提高网络生命周期.分析了大型设备周边无线信道特征,针对小尺度衰落及设备运转时对信号的随机遮挡,提出一种多簇头协作式超簇结构的无线传感器网络.仿真结果表明,超簇结构无线传感器网络的网络连通度及网络生存期明显优于传统无线传感器网络.     

强噪声海量物联网数据处理中节点选择算法研究

当前节点选择算法在强噪声干扰下,通过优先级理论实现节点选择,存在安全性差、能耗高、整体性能低下的弊端,为此,提出一种新的强噪声海量物联网数据处理中节点选择算法。将数字序列中某点的值用与该点相邻的各点值的中值替换,通过中值滤波法对物联网中的强噪声进行去除,完成强噪声干扰去除后。通过基于后悔函数的平衡剩余能量节点选择算法对海量物联网数据处理中节点进行选择。依据误码率选择满足要求的节点作为候选节点,通过减少无效处理增强能量性能。利用后悔函数对节点相对物联网的剩余能量进行估算,依据节点相对于其他节点的剩余能量确定延迟时间,从而实现节点选择。实验结果表明,采用所提算法对海量物联网数据处理中节点进行选择,不仅安全性高,而且节能性好、整体性能高。     

Non-random coextinctions in phylogenetically structured mutualistic networks

The interactions between plants and their animal pollinators and seed dispersers have moulded much of Earth's biodiversity. Recently, it has been shown that these mutually beneficial interactions form complex networks with a well-defined architecture that may contribute to biodiversity persistence. Little is known, however, about which ecological and evolutionary processes generate these network patterns. Here we use phylogenetic methods to show that the phylogenetic relationships of species predict the number of interactions they exhibit in more than one-third of the networks, and the identity of the species with which they interact in about half of the networks. As a consequence of the phylogenetic effects on interaction patterns, simulated extinction events tend to trigger coextinction cascades of related species. This results in a non-random pruning of the evolutionary tree and a more pronounced loss of taxonomic diversity than expected in the absence of a phylogenetic signal. Our results emphasize how the simultaneous consideration of phylogenetic information and network architecture can contribute to our understanding of the structure and fate of species-rich communities.     

无线传感器网络能量优化的研究综述

针对无线传感器网络能量受限,每个传感器的网络生命时间都特别依赖节点的电池能量问题,以无线传感器网络体系结构为主线,总结了协议栈各层提高能量效率从而延长网络生命时间的主要技术手段,讨论了延长传感器网络生命时间的未来发展方向。     

主动网络管理技术研究

提出一种基于主动网络技术的网络管理体系结构。通过将网管主动包委派到被管对象附近的网管主动节点，快速主动地发现和处理网络事件，从而克服传统网络管理技术存在的管理效率低、伸缩性差的缺陷，实现分布式的智能网络管理。网管主动节点和主动包是该体系结构中的2个基本部件，文中给出了它们的构造方法。该主动网络管理体系结构不但能集成到目前的TCP／IP网络中，满足该类网络的管理需要，而且还能平滑过渡到对未来主动网络的管理。     

考虑节点能量消耗的无线传感网络平衡路由算法设计

传统方法设计无线传感网络路由中,往往忽略了节点的能量消耗以及不同节点能耗的差异性,导致出现节点分布不均匀、路由平衡度较差、整体开销成本较大、能耗高等问题。为此,提出了考虑节点能量消耗的无线传感网络平衡路由算法。构建节点能耗模型,建立无线传感网络梯度和传感器节点之间的信息素,结合蚁群算法求解整体能耗模型,实现无线传感网络平衡路由的算法设计。实验结果表明,所提方法可提高无线传感网络中节点的均匀分布能力,降低整体能耗开销,减少能量消耗,有效实现无线传感网络平衡路由的算法设计。     

Error and attack tolerance of complex networks

Many complex systems display a surprising degree of tolerance against errors. For example, relatively simple organisms grow, persist and reproduce despite drastic pharmaceutical or environmental interventions, an error tolerance attributed to the robustness of the underlying metabolic network. Complex communication networks display a surprising degree of robustness: although key components regularly malfunction, local failures rarely lead to the loss of the global information-carrying ability of the network. The stability of these and other complex systems is often attributed to the redundant wiring of the functional web defined by the systems' components. Here we demonstrate that error tolerance is not shared by all redundant systems: it is displayed only by a class of inhomogeneously wired networks, called scale-free networks, which include the World-Wide Web, the Internet, social networks and cells. We find that such networks display an unexpected degree of robustness, the ability of their nodes to communicate being unaffected even by unrealistically high failure rates. However, error tolerance comes at a high price in that these networks are extremely vulnerable to attacks (that is, to the selection and removal of a few nodes that play a vital role in maintaining the network's connectivity). Such error tolerance and attack vulnerability are generic properties of communication networks.     

Combining Topological Properties and Strong Ties for Link Prediction

Link prediction is an important task that estimates the probability of there being a link between two disconnected nodes. The similarity-based algorithm is a very popular method that employs the node similarities to find links. Most of these types of algorithms focus only on the contribution of common neighborhoods between two nodes. In sociological theory relationships within three degrees are the strong ties that can trigger social behaviors.Thus, strong ties can provide more connection opportunities for unconnected nodes in the networks. As critical topological properties in networks, nodes degrees and node clustering coefficients are well-suited for describing the tightness of connections between nodes. In this paper, we characterize node similarity by utilizing the strong ties of the ego network(i.e., paths within three degrees) and its close connections(node degrees and node clustering coefficients). We propose a link prediction algorithm that combines topological properties with strong ties, which we called the TPSR algorithm. This algorithm includes TPSR2, TPSR3, and the TPSR4 indices. We evaluate the performance of the proposed algorithm using the metrics of precision and the Area Under the Curve(AUC). Our experimental results show the TPSR algorithm to perform remarkably better than others.     

基于两跳邻居的ZigBee网络借地址分配算法

针对标准DAAM算法可能产生网络深度折回问题及父节点可分配的地址空间分布不均,提出一种基于两跳邻居的ZigBee网络借地址分配算法。通过控制子节点发送地址请求信息的监测范围设为两跳通信距离内的邻居节点,并改进实时路由,实现优化网络拓扑结构,减少孤立节点。理论和仿真分析表明改进算法在地址分配成功率,地址分配平均耗时等方面优于DAAM算法。     

Research on Architecture Design with High Reliability of Network Nodes in the Amphibious Combating Simulation System

Upper-lower computer mode is the main architecture design of the amphibious combat simulation system(ACSS) at present. Through continuous improvement of real-time performance, software and hardware infrastructure, the exponential growth of operational network data scale is realized, but the availability performance of ACSS declines. The reliability of the working host as the key node has become the bottleneck of the overall availability of network nodes in the ACSS. To optimize the network node architecture of ACSS, this paper presents an effective optimization solution by designing the dual redundancy warm-standby module of the mission computer and I/O port, the algorithm of selecting output path of the mission computer in network nodes, the decision-making algorithm upon the on-duty host and output, and the video output decision-making algorithm upon the upper host. Lastly, the complete process of operational data from the input to output and the opposite is implemented well to guarantee the overall availability of network nodes in the ACSS. It has great advantages of wide applicability, strong reliability and high real-time switching speed.     

内容寻址网络的P2P语义Web服务组合系统架构

为了提高语义Web服务组合系统的扩展性、可靠性和稳定性,提出了一种基于P2P的语义Web服务(P2PSWS)组合系统架构.该架构结合了集中式和分布式结构的优点,将统一描述、发现和集成协议的功能分散于本地Web节点、组Web节点和公共Web节点;设计了一种基于内容寻址网络的P2P网络语义Web服务的定位机制,以保证每个共享服务按领域划分,按被所有节点所共享的公共Web节点来注册.原型系统运行表明,该架构有助于克服传统公共Web服务结构上的单一节点失败问题,扩展了P2P系统的能力,有效地实现了基于本体的语义Web服务的组合.     

A Novel Active Network Architecture Based on Extensible Services Router

Active networks are a new kind of packet-switched networks in which packets have code fragments that are executed on the intermediary nodes (reuters). The code can extend or modify the foundation architecture of a network. In this paper, the authors present a novel active net-work architecture combined with advantages of two major active networks technology based on extensible services muter. The architecture consists of extensible service muter, active extensible components server and key distribution center (KDC). Users can write extensible service ~mpo-nents with programming interface. At the present time, we have finished the extensible services muter prototype system based on Highly Efficient Router Operating System (HEROS), active extensible components server and KDC prototype system based on Linux.     

HEAD:A Hybrid Mechanism to Enforce Node Cooperation in Mobile Ad Hoc Networks

Mobile ad hoc networks rely on the cooperation of nodes for routing and forwarding. However, it may not be advantageous for individual nodes to cooperate. In order to make the mobile ad hoc network more robust, we propose a scheme called HEAD (a hybrid mechanism to enforce node cooperation in mobile ad hoc networks) to make the misbehavior unattractive. HEAD is an improvement to OCEAN (observation-based cooperation enforcement in ad hoc networks). It employs only first hand information and works on the top of DSR (dynamic source routing) protocol. By interacting with the DSR, HEAD can detect the misbehavior nodes in the packet forwarding process and isolate them in the route discovery process. In order to detect the misbehavior nodes quickly, HEAD introduces the warning message. In this paper, we also classify the misbehavior nodes into three types:malicious nodes, misleading nodes, and selfish nodes. They all can be detected by HEAD, and isolated from the network.     

Efficient statistical analysis method of power/ground （P/G） network

In this paper, we propose an incremental statistical analysis method with complexity reduction as a pre-process for on-chip power/ ground （P/G） networks. The new method exploits locality of P/G network analyses and aims at P/G networks with a large number of strongly connected subcircuits （called strong connects） such as trees and chains. The method consists of three steps. First it compresses P/ G circuits by removing strong connects. As a result, current variations （CVs） of nodes in strong connects are transferred to some remaining nodes. Then based on the locality of power grid voltage responses to its current inputs, it efficiently calculates the correlative resistor （CR） matrix in a local way to directly compute the voltage variations by using small parts of the remaining circuit. Last it statistically recovers voltage variations of the suppressed nodes inside strong connects. This new method for statistically compressing and expanding strong connects in terms of current or voltage variations in a closed form is very efficient owning to its property of incremental analysis. Experimental results demonstrate that the method can efficiently compute low-bounds of voltage variations for P/G networks and it has two or three orders of magnitudes speedup over the traditional Monte-Carlo-based simulation method, with only 2.0% accuracy loss.     

Deepflow: Hiding anonymous communication traffic in P2P streaming networks

The anonymous communication systems usually have special traffic patterns, which can be detected by censors for further disturbing or blocking. To solve this problem, we present a novel system, Deepflow, to hide anonymous communication traf- fic into the P2P streaming networks such as PPStream by using steganography. Each Deepflow node joins the PPStream network and performs like a normal PPStream client watching a live chan- nel, while embedding communication data into video packets transferred in the network. The steganographed video packets are disseminated by innocuous PPStream clients and reach the target Deepflow node. It is not necessary for Deepflow nodes to link together in the network, which prevents malicious users from sensing IP address of other Deepflow nodes. Deepflow is competent for secret chatting, transferring text documents, or publishing secret bootstrapping information for other anonymous communication systems. Comprehensive experiments in real network environments are conducted in this paper to show the security and efficiency of Deepflow.     

应用复杂网络研究板块内股票的强相关性

为探索股票之间相互影响的行为,提高投资组合构建能力,以中国股市煤炭、电力板块股票为节点,以近19年股票对数回报的相关系数为边,建立复杂网络模型。通过对网络拓扑参数计算,发现该网络为无尺度网络,节点度分布负幂指数小于1,无权网络和加权网络平均集聚系数分别为0.68和0.41。对网络中心性进行了测量,发现000723,601898,601918三个节点是整个网络的核心节点;网络可划分成两个分区,并抽取出一个高度耦合的具有13个节点的中心网络,对整体网络有很大影响。     

Efficient statistical analysis method of power/ground(P/G) network

In this paper, we propose an incremental statistical analysis method with complexity reduction as a pre-process for on-chip power/ground (P/G) networks. The new method exploits locality of P/G network analyses and aims at P/G networks with a large number of strongly connected subcircuits(called strong connects) such as trees and chains. The method consists of three steps. First it compresses P/G circuits by removing strong connects. As a result, current variations (CV) of nodes in strong connects are transferred to some remaining nodes. Then based on the locality of power grid voltage responses to its current inputs, it efficiently calculates the correlative resistor (CR) matrix in a local way to directly compute the voltage variations by using small parts of the remaining circuit. Last it statistically recovers voltage variations of the suppressed nodes inside strong connects. This new method for statistically compressing and expanding strong connects in terms of current or voltage variations in a closed form is very efficient owning to its property of incremental analysis. Experimental results demonstrate that the method can efficiently compute low-bounds of voltage variations for P/G networks and it has two or three orders of magnitudes speedup over the traditional Monte-Carlo-based simulation method, with only 2.0% accuracy loss.