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1.
Effects of vertex activity have been analyzed on a weighted evolving network. The network is characterized by the probability distribution of vertex strength, each edge weight and evolution of the strength of vertices with different vertex activities. The model exhibits self-organized criticality behavior. The probability distribution of avalanche size for different network sizes is also shown. In addition, there is a power law relation between the size and the duration of an avalanche and the average of avalanche size has been studied for different vertex activities.  相似文献   

2.
张争珍  许文俊  曾上游  林家儒 《中国物理 B》2014,23(2):28902-028902
In this paper, the general efficiency, which is the average of the global efficiency and the local efficiency, is defined to measure the communication efficiency of a network. The increasing ratio of the general efficiency of a small-world network relative to that of the corresponding regular network is used to measure the small-world effect quantitatively. The more considerable the small-world effect, the higher the general efficiency of a network with a certain cost is. It is shown that the small-world effect increases monotonically with the increase of the vertex number. The optimal rewiring probability to induce the best small-world effect is approximately 0.02 and the optimal average connection probability decreases monotonically with the increase of the vertex number. Therefore, the optimal network structure to induce the maximal small-world effect is the structure with the large vertex number (〉 500), the small rewiring probability (≈0.02) and the small average connection probability (〈 0.1). Many previous research results support our results.  相似文献   

3.
Though applying master stability function method to analyse network complete synchronization has been well studied in chaotic dynamical systems, it does not work well for phase synchronization. Moreover, it is difficult to identify phase synchronization with the angle of rotation for non-phase-coherent attractors. We employ the recurrences plot method to detect phase synchronization for several regular networks with non-phase-coherent attractors. It is found that the coupling strength μ is different for different coupled networks. The coupling strength μ is reduced as completed coupled network scale enlarges, the coupling strength μ of star coupled network is irrelevant to network scale, and these two regular networks are easier to achieve phase synchronization. However, for ring and chain coupled networks, the larger the phase synchronization couple strength μ is, the larger the network scale is, and it is more difficult to achieve phase synchronization. For same scale network, once ring coupled structure becomes a chain coupled structure, phase synchronization becomes much more difficult.  相似文献   

4.
刘兆冰  张化光  孙秋野 《中国物理 B》2010,19(9):90506-090506
This paper considers the global stability of controlling an uncertain complex network to a homogeneous trajectory of the uncoupled system by a local pinning control strategy. Several sufficient conditions are derived to guarantee the network synchronisation by investigating the relationship among pinning synchronisation, network topology, and coupling strength. Also, some fundamental and yet challenging problems in the pinning control of complex networks are discussed: (1) what nodes should be selected as pinned candidates? (2) How many nodes are needed to be pinned for a fixed coupling strength? Furthermore, an adaptive pinning control scheme is developed. In order to achieve synchronisation of an uncertain complex network, the adaptive tuning strategy of either the coupling strength or the control gain is utilised. As an illustrative example, a network with the Lorenz system as node self-dynamics is simulated to verify the efficacy of theoretical results.  相似文献   

5.
We investigate the navigation process on a variant of the Watts-Strogatz small-world network model with local information. In the network construction, each vertex of an N x N square lattice sends out a long-range link with probability p. The other end of the link falls on a randomly chosen vertex with probability proportional to r^-α, where r is the lattice distance between the two vertices, and α ≥ 0. The average actual path length, i.e. the expected number of steps for passing messages between randomly chosen vertex pairs, is found to scale as a power-law function of the network size N^β, except when α is close to a specific value value, which gives the highest efficiency of message navigation. For a finite network, the exponent β depends on both α and p, and p αmin drops to zero at a critical value of p which depends on N. When the network size goes to infinity,β depends only only on α, and αmin is equal to the network dimensionality.  相似文献   

6.
韦笃取  张波  丘东元  罗晓曙 《中国物理 B》2010,19(10):100513-100513
Recent experimental evidence suggests that some brain activities can be assigned to small-world networks. In this work, we investigate how the topological probability p and connection strength C affect the activities of discrete neural networks with small-world (SW) connections. Network elements are described by two-dimensional map neurons (2DMNs) with the values of parameters at which no activity occurs. It is found that when the value of p is smaller or larger, there are no active neurons in the network, no matter what the value of connection strength is; for a given appropriate connection strength, there is an intermediate range of topological probability where the activity of 2DMN network is induced and enhanced. On the other hand, for a given intermediate topological probability level, there exists an optimal value of connection strength such that the frequency of activity reaches its maximum. The possible mechanism behind the action of topological probability and connection strength is addressed based on the bifurcation method. Furthermore, the effects of noise and transmission delay on the activity of neural network are also studied.  相似文献   

7.
The coupling vertex of the Pomeron to nucleon is derived from QCD. A γμ coupling vertex and coupling strength of β= 6.0 GeV-1, which has been used commonly as a free parameter in literature, are obtained. The result leads a support to the belief that the Pomeron could be a tensor glueball ξ(2230) with quantum numbers of IGJPC = 0+2++ in nature.  相似文献   

8.
李凌  金贞兰  李斌 《中国物理 B》2011,20(3):38701-038701
Rhythm of brain activities represents oscillations of postsynaptic potentials in neocortex,therefore it can serve as an indicator of the brain activity state.In order to check the connectivity of brain rhythm,this paper develops a new method of constructing functional network based on phase synchronization.Electroencephalogram(EEG) data were collected while subjects looking at a green cross in two states,performing an attention task and relaxing with eyes-open.The EEG from these two states was filtered by three band-pass filters to obtain signals of theta(4-7 Hz),alpha(8-13 Hz) and beta(14-30 Hz) bands.Mean resultant length was used to estimate strength of phase synchronization in three bands to construct networks of both states,and mean degree K and cluster coefficient C of networks were calculated as a function of threshold.The result shows higher cluster coefficient in the attention state than in the eyes-open state in all three bands,suggesting that cluster coefficient reflects brain state.In addition,an obvious fronto-parietal network is found in the attention state,which is a well-known attention network.These results indicate that attention modulates the fronto-parietal connectivity in different modes as compared with the eyes-open state.Taken together this method is an objective and important tool to study the properties of neural networks of brain rhythm.  相似文献   

9.
China has the largest high-speed railway(HSR) system in the world, and it has gradually reshaped the urban network.The HSR system can be represented as different types of networks in terms of the nodes and various relationships(i.e.,linkages) between them. In this paper, we first introduce a general dual network model, including a physical network(PN)and a logical network(LN) to provide a comparative analysis for China’s high-speed rail network via complex network theory. The PN represents a layout of stations and rail tracks, and forms the basis for operating all trains. The LN is a network composed of the origin and destination stations of each high-speed train and the train flows between them. China’s high-speed railway(CHSR) has different topological structures and link strengths for PN in comparison with the LN. In the study, the community detection is used to analyze China’s high-speed rail networks and several communities are found to be similar to the layout of planned urban agglomerations in China. Furthermore, the hierarchies of urban agglomerations are different from each other according to the strength of inter-regional interaction and intra-regional interaction, which are respectively related to location and spatial development strategies. Moreover, a case study of the Yangtze River Delta shows that the hub stations have different resource divisions and are major contributors to the gap between train departure and arrival flows.  相似文献   

10.
Two modified Dorogovtsev-Mendes (DM) models of aging networks based on the dynamics of connecting nearest-neighbors are introduced. One edge of the new site is connected to the old site with probability - kt^-α as in the DM's model, where the degree and age of the old site are k and t, respectively. We consider two cases, i.e. the other edges of the new site attaching to the nearest-neighbors of the old site with uniform and degree connectivity probability, respectively. The network structure changes with an increase of aging exponent α It is found that the networks can produce scale-free degree distributions with small-world properties. And the different connectivity probabilities lead to the different properties of the networks.  相似文献   

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