Evolutionary snowdrift game on heterogeneous Newman-Watts small-world network

We study the evolutionary snowdrift game in a heterogeneous Newman-Watts small-world network. The heterogeneity of the network is controlled by the number of hubs. It is found that the moderate heterogeneity of the network can promote the cooperation best. Besides, we study how the hubs affect the evolution of cooperative behaviours of the heterogeneous Newman-Watts small-world network. Simulation results show that both the initial states of hubs and the connections between hubs can play an important role. Our work gives a further insight into the effect of hubs on the heterogeneous networks.

Homogeneous and Heterogeneous Traffic of Data Packets on Complex Networks: The Traffic Congestion Phenomenon

We study the congestion phenomenon in a mathematical model of the data packets traffic in transmission networks as a function of the topology and of the load of the network. Two types of traffic are considered: homogeneous and heterogeneous traffic. The congestion phenomenon is studied in stationary conditions through the behaviour of two quantities: the mean travel time of a packet and the mean number of packets that have not reached their destination and are traveling in the network. We define a transformation that maps a network having the small world property (Inet 3037 in our numerical experiments) into a (modified) lattice network that has the same number of nodes. This map changes the capacity of the branches of the graphs representing the networks and can be regarded as an “interpolation” between the two classes of networks. Using this transformation we compare the behaviour of Inet 3037 to the behaviour of a modified rectangular lattice and we study the behaviour of the interpolating networks. This study suggests how to change the network topology and the branch capacities in order to alleviate the congestion phenomenon. In the website: http://www.ceri.uniroma1.it/ceri/zirilli/w6 some auxiliary material including animations and stereo?graphic scenes that helps the understanding of this paper is shown.

Topological Properties of Urban Public Traffic Networks in Chinese Top-Ten Biggest Cities

We investigate the topological characteristics of complex networks as exemplified by the urban public traffic network （UPTN） in Chinese top-ten biggest cities. It is found that the UPTNs have small world behaviour, by the examination of their topological parameters. The quantitative analysis of the transport efficiency of the UPTNs reveals their higher local efficiency El and lower global efficiency Eg, which coincide well with the status quo of those Chinese cities still at their developing stage. Furthermore, the topological properties of efficiency in the UPTNs are also examined, and the findings indicate that, on the one hand, the UPTNs show robustness to random attacks and frangibility to malicious attacks on a global scale; on the other hand, the interrelation between UPTN efficiency and network motifs deserves our attention. The motifs which interrelate the UPTN efficiency are always triangular-formed patterns, e.g. motifs ID 238, ID 174 and ID 102, etc.

Step-by-Step Random Walk Network with Power-Law Clique-Degree Distribution

We propose a simple mechanism for generating scale-free networks with degree exponent γ=3, where the new node is connected to the existing nodes by step-by-step random walk. It is found that the clique-degree distribution based on our model obeys a power-law form, which is in agreement with the recently empirical evidences. In addition, our model displays the small-world effect and the hierarchical structure.

Opinion Spreading with Mobility on Scale-Free Networks

A continuum opinion dynamic model is presented based on two rules. The first one considers the mobilities of the individuals, the second one supposes that the individuals update their opinions independently. The results of the model indicate that the bounded confidence εc, separating consensus and incoherent states, of a scale-free network is much smaller than the one of a lattice. If the system can reach the consensus state, the sum of all individuals＇ opinion change Oc（t） quickly decreases in an exponential form, while if it reaches the incoherent state finally, Oc（t） decreases slowly and has the punctuated equilibrium characteristic.

Structures and dynamics of scientific knowledge networks:An empirical analysis based on a co-word network

Co-word networks are constructed with author-provided keywords in academic publications and their relations of co-occurrence.As special form of scientific knowledge networks,they represent the cognitive structure of scientific literature.This paper analyzes the complex structure of a co-word network based on 8,190 author-provided keywords extracted from 3,651 papers in five Chinese core journals in the field of management science.Small-world and scale-free phenomena are found in this network.A large-scale co-word network graph,which consists of one major giant component and many small isolated components,has been generated with the GUESS software.The dynamic growth of keywords and keyword co-occurrence relationships are described with four new informetrics measures.The results indicate that existing concepts always serve as the intellectual base of new ideas as represented by keywords.

Optimizing Synchronizability of Scale-Free Networks in Geographical Space

We investigate the relationship between the structure and the synchronizability of scale-free networks in geographical space. With an optimization approach, the numerical results indicate that when the network synchronizability is improved, the geographical distance becomes larger while the maximal load decreases. Thus the maximal betweenness can be a candidate factor that affects the network synchronizability both in topological space and in geographical space.

Evolving Networks with Nonlinear Assignment of Weight

We propose a weighted evolving network model in which the underlying topological structure is still driven by the degree according to the preferential attachment rule while the weight assigned to the newly established edges is dependent on the degree in a nonlinear form. By varying the parameter a that controls the function determining the assignment of weight, a wide variety of power-law behaviours of the total weight distributions as well as the diversity of the weight distributions of edges are displayed. Variation of correlation and heterogeneity in the network is illustrated as well.

Improvement of Synchronizability of Scale-Free Networks

We investigate the factors that affect synchronizability of coupled oscillators on scale-free networks. Using the memory Tabu search （MTS） algorithm, we improve the eigen-ratio Q of a coupling matrix by edge intercrossing. The numerical results show that the synchronizatlon-improved scale-free networks should have distinctive both small average distance and larger clustering coefficient, which are consistent with some real-world networks. Moreover, the synchronizability-improved networks demonstrate the disassortative coefficient.

Power law and small world properties in a comparison of traffic city networks

<Abstract>We analyze the statistical properties of the urban public bus networks of two cities (Beijing and Chengdu) in China. To this end, we present a comprehensive survey of the degree distribution, average path length, and clustering of both networks. It is shown that both networks exhibit small world behavior and are hierarchically organized. We also discuss the differences between the statistical properties displayed by the two networks. In addition, we propose a weight distribution approach to study the passenger flow through the public bus networks we considered. A hierarchical structure is observed here also.

《水浒传》人物关系网络分析

复杂网络作为复杂系统的一种抽象描述,可用于文学作品中人物关系网络的建模工具。以《水浒传》中的108将为研究对象,采用复杂网络分析方法对该作品中的人物关系进行构建与分析,小说中的人物对应于网络中的节点,人物之间的关系对应于网络中的边。人工搜索标记人物名称,以任意两个人物在同一章回的共现关系为前提,构建人物关系网络,并计算度、介数、集聚系数、稀疏性、相关性等网络指标。结果表明《水浒传》人物关系网络是异配网络,并且具有小世界特性和社区特性。

基于复杂网络演化博弈的无线传感器网络入侵检测方法

针对无线传感器网络资源受限和入侵检测系统策略优化问题,本文提出一种基于复杂网络演化博弈的无线传感器网络入侵检测方法。结合小世界模型理论,模拟网络节点之间的连接关系,在不改变节点原有关系的前提下增强网络连通性并降低传输能耗;构建关于簇头节点和恶意节点的无线传感器网络攻防博弈模型,通过收益矩阵计算节点收益,利用奖惩机制描述节点在博弈过程中选择不同策略的收益变化;引入经验加权吸引力学习算法改进传统博弈的策略更新规则并将该算法应用于入侵检测系统,使得簇头节点能够动态更新策略选择,得到不同条件下的入侵检测最优策略。实验结果表明,与传统方法相比,所提算法的簇头节点检测策略扩散深度可以达到79%,该算法下簇头节点在保障自身检测收益的同时尽可能选择检测传感器网络中出现的攻击,保证网络检测率并减少网络各类资源的消耗。

Complexity of Public Transport Networks

The theory of complex networks was used to classify public transport networks into public transportation route networks, public transportation transfer networks, and bus station networks. The practical significance of the network parameters was then analyzed. The public transport networks in Langfang, Jining, and Dalian were then chosen as specific research cases. The results show that the public transportation networks have the characteristics of complex networks, In addition, the urban transportation network parameters all significantly affect the accessibility, convenience, and terrorist security capability of the urban public transportation network. The results link the findings with the actual situations to explore means to solve transportation system problems.

基于复杂网络理论的汉语“N+N”组块网络研究

“组块”最初是认知理论中提出的概念,被看作语言记忆和存储、输出和使用的最小单位,符合认知规律,能够有效强化认知操作。“网络”是由若干节点和边构成的图(Graph),表示诸多对象及其相互联系。作为新兴热点科学,复杂网络是对存在的网络现象及其复杂性进行解释的学科。语言网络是一种极为复杂的网络。运用复杂网络理论及方法对汉语组块结构进行定量描述与定性分析,发现汉语“N+N”组块网络是小世界网络,其度分布服从幂律分布,是一种无标度网络。从生物性角度来看,组块网络受人类使用影响程度较大,属于社会网络。

复杂网络视角下交通网络拓扑结构分析

对交通流量数据构建复杂的网络模型,从矩阵视角对其拓扑结构进行分析。结果表明,此交通复杂网络位置节点的度分布符合幂律分布,即BA无标度网络。经过对数据处理,聚类系数较大,平均路径长度较小,网络呈小世界性,通过MATLAB分析数据得到Laplace矩阵的特征值,得到此网络的同步能力较弱。相关部门可根据此结果对公共交通及共享交通工具进行合理安排及调整,进一步提升通行效率及公共资源的利用率,使拥堵现象和资源浪费导致的环境污染问题得到缓解。

复杂网络理论与城市交通系统复杂性问题的相关研究

首先综述了当今关于小世界网络、无标度网络以及复杂加权网络的最新研究成果,并从城市交通系统的角度出发,指出了综合利用复杂网络理论、动力系统理论、现代控制理论及交通科学和工程等多学科的理论与方法,在探索城市交通网络的时空复杂性及其演化机理,揭示交通流的演化过程,缓解和预防交通拥堵,指导交通实践等方面,都具有重大的科学理论意义与实际应用价值,是值得深入研究与探讨的大问题.并进一步指出了一些今后关于城市交通网络复杂性问题的研究主题.

网络结构鲁棒性指标及应用研究

为了更好地测度网络抵御破坏的能力,基于网络连通和恢复能力提出了连接鲁棒性和恢复鲁棒性两种指标.运用这两种指标,以网络规模为500,取20次独立实验的均值,对ER随机网络、规则网络、BA无标度网络以及WS小世界网络4种典型网络结构进行仿真.实验结果表明:ER随机网络对于恶意攻击的鲁棒性要优于其他3种网络;BA无标度网络仅节点恢复鲁棒性较好,边恢复鲁棒性和连接鲁棒性最差;规则网络拥有很好的连接鲁棒性但恢复鲁棒性最差;WS小世界网络受其参数影响,鲁棒性介于ER随机网络和规则网络之间.同时还发现,网络结构鲁棒性的下降随着去除节点个数的增加和网络结构参数的改变而呈现出一定的"涌现"现象.

中国航空网络空间结构的复杂性

航空运输是现代交通运输的重要组成部分,以机场和航线构建的网络是其提供运输服务的空间载体。基于复杂网络理论,借助度分布、平均路径长度、簇系数、度度相关性、簇度相关性等指标对以城市为节点的中国航空网络空间结构进行分析,发现其度累计概率分布表现为具有置信度较高的指数分布,且具有较小的平均路径长度(2.23)和较大的簇系数(0.69),整体结构呈现"小世界网络"的特点。由于中国航空网络规模较小,且新建机场倾向于直接与最高级枢纽机场建立航线联系,不利于区域枢纽机场的形成。因而除顶层结构(北京—上海—广州)外,中国航空网络的其它层级结构并不十分明显。从节点的度、簇系数、可达性等指标及其相关性分析,中国航空网络空间结构特征差异明显,表现出较强的集聚性,且可达性与城市体系上层结构在空间分布上较为吻合。随着中国航空运输需求的快速增加,未来航空网络在市场经济的推动下,将进一步表现出向具有"无标度"特征的"小世界网络"演变的趋势,航空网络的空间结构将日趋复杂化。

复杂网络上动力系统同步的研究进展

本文简要介绍复杂网络的基本概念并详细总结了近年来复杂网络上动力学系统的同步的研究进展,主要内容有复杂网络同步的稳定性分析,复杂网络上动力学系统同步的特点,网络的几何特征量对同步稳定性的影响,以及提高网络同步能力的方法等。最后文章提出了这一领域的几个有待解决的问题及可能的发展方向。

电力调度数据网结构特性分析

提出运用复杂网络理论从结构的角度分析电力调度数据网的复杂性及脆弱性。现有的电力调度数据网大致可分为双星型和网状2种典型结构,从统计特征参数、度数累积分布以及介数累积分布3个方面对这2种电力调度数据网的结构进行了分析,发现双星型网是典型的无标度网络,而网状网是典型的小世界网络。继而以单一故障和连锁故障分别衡量了2种网络的静态脆弱性和动态脆弱性。结果表明:1)电力调度数据网的脆弱性与其网络结构有很大的联系,单一故障时,双星型结构的调度数据网对选择性攻击表现得更加脆弱;2)双星型结构的调度数据网不容易发生连锁故障,网状结构反之。连锁故障时故障概率较高的节点仍集中在介数高的节点。