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1.
In the study of complex networks,it is commonly believed that the eigenratio λ2/λ N of the Laplacian matrix of a network represents the network synchronizability,especially for symmetric networks.This paper gives two counterexamples to show that this is not true for the case where the network has a disconnected synchronized region.Consequently,a simple answer is presented to the question of when the eigenratio λ2/λ N does represent the network synchronizability. 相似文献
2.
Does the eigenratio λ<sub>2</sub>/λ<sub>N</sub> represent the synchronizability of a complex network?
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In the study of complex networks,it is commonly believed that the eigenratio λ2/λ N of the Laplacian matrix of a network represents the network synchronizability,especially for symmetric networks.This paper gives two counterexamples to show that this is not true for the case where the network has a disconnected synchronized region.Consequently,a simple answer is presented to the question of when the eigenratio λ2/λ N does represent the network synchronizability. 相似文献
3.
Undetermination of the synchronizability and relation between network betweenness centrality
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Betweenness centrality is taken as a sensible indicator of the synchronizability of complex networks. To test whether betweenness centrality is a proper measure of the synchronizability in specific realizations of random networks, this paper adds edges to the networks and then evaluates the changes of betweenness centrality and network synchronizability. It finds that the two quantities vary independently. 相似文献
4.
In this paper, the relationship between network
synchronizability and the edge-addition of its associated graph is
investigated. First, it is shown that adding one edge to a cycle
definitely decreases the network synchronizability. Then, since
sometimes the synchronizability can be enhanced by changing the
network structure, the question of whether the networks with more
edges are easier to synchronize is addressed. Based on a subgraph
and complementary graph method, it is shown by examples that the
answer is negative even if the network structure is arbitrarily
optimized. This reveals that generally there are redundant edges in
a network, which not only make no contributions to synchronization
but actually may reduce the synchronizability. Moreover, a simple
example shows that the node betweenness centrality is not always a
good indicator for the network synchronizability. Finally, some more
examples are presented to illustrate how the network
synchronizability varies following the addition of edges, where all
the examples show that the network synchronizability globally
increases but locally fluctuates as the number of added edges
increases. 相似文献
5.
Undetermination of the relation between network synchronizability and betweenness centrality
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Betweenness centrality is taken as a sensible indicator of the synchronizability of complex networks. To test whether betweenness centrality is a proper measure of the synchronizability in specific realizations of random networks,this paper adds edges to the networks and then evaluates the changes of betweenness centrality and network synchronizability. It finds that the two quantities vary independently. 相似文献
6.
Synchronizability of complex oscillators networks has attracted much
research interest in recent years. In contrast, in this paper we
investigate numerically the synchronization speed, rather than the
synchronizability or synchronization stability, of identical
oscillators on complex networks with communities. A new weighted
community network model is employed here, in which the community
strength could be tunable by one parameter δ. The results
showed that the synchronization speed of identical oscillators on
community networks could reach a maximal value when δ is
around 0.1. We argue that this is induced by the competition
between the community partition and the scale-free property of the
networks. Moreover, we have given the corresponding analysis through
the second least eigenvalue λ2 of the Laplacian matrix of
the network which supports the previous result that the
synchronization speed is determined by the value of λ2. 相似文献
7.
DAI Kun WANG Xiao-Fan LI Xiang 《理论物理通讯》2008,49(4):1064-1068
In this paper, we propose two methods to enhance the synchronizability of a class of complex networks which do not hold the positive correlation between betweenness centrality (BC) and degree of a node, and observe other topology characteristics of the network affected by the methods. Numerical simulations show that both methods can effectively enhance the synchronizability of this kind of networks. Furthermore, we show that the maximal BC of all edges is an important factor to affect the network synchronizability, although it is not the unique factor. 相似文献
8.
<正>According to different forms of synchronized region,complex networks are divided into typeⅠ(unbounded synchronization region) and typeⅡ(bounded synchronization region) networks.This paper presents a rewiring algorithm to enhance the synchronizability of typeⅠand typeⅡnetworks.By utilizing the algorithm for an unweighted and undirected network,a better synchronizability of network with the same number of nodes and edges can be obtained. Numerical simulations on several different network models are used to support the proposed procedure.The relationship between different topological properties of the networks and the number of rewirings are shown.It finds that the final optimized network is independent of the initial network,and becomes homogeneous.In addition the optimized networks have similar structural properties in the sense of degree,and node and edge betweenness centralities.However,they do not have similar cluster coefficients for typeⅡnetworks.The research may be useful for designing more synchronizable networks and understanding the synchronization behaviour of networks. 相似文献
9.
The collective synchronization of a system of coupled logistic maps on random community networks is investigated. It is found that the synchronizability of the community network is affected by two factors when the size of the network and the number of connections are fixed. One is the number of communities denoted by the parameter rn, and the other is the ratio σ of the connection probability p of each pair of nodes within each community to the connection probability q of each pair of nodes among different communities. Theoretical analysis and numerical results indicate that larger rn and smaller σ are the key to the enhancement of network synchronizability. We also testify synchronous properties of the system by analysing the largest Lyapunov exponents of the system. 相似文献
10.
The influence of structural properties of a network on the network synchronizability is studied by introducing a new concept of average range of edges. For both small-world and scale-free networks, the effect of average range on the synchronizability of networks with bounded or unbounded synchronization regions is illustrated through numerical simulations. The relations between average range, range distribution, average distance, and maximum betweenness are also explored, revealing the effects of these factors on the network synchronizability of the small-world and scale-free networks, respectively. 相似文献
11.
In this paper, an evolutionary model of bus transport network in B-space is developed. It includes the effect of the overlapping ratio of new route on network performance and overcomes the disadvantage, i.e. lack of economic consideration, in the evolutionary bus transport network model in P-space proposed by Chen et al (2007). The degree distribution functions are derived by using the mean-field method and the master equation method, separately. The relationship between the new stop ratio of a route, λ, and the error in exponential of degree distribution function from the mean-field method is developed as ASlope= λ/(1 -λ) + ln(1-λ). Finally, the bus transport networks of Hangzhou and Nanjing are simulated by using this model, and the results show that some characteristic index values of the simulated networks are closer to the empirical data than those from Chen's model. 相似文献
12.
Synchronization between two networks with different topology structures and different dynamical behaviours is studied. These two different networks are driving and responding networks, respectively. Under the preconditions that the driving network gets synchronization, we give the conditions for the responding network to be synchronized to the same dynamics as the driving network with the help of the open-plus-closed-loop method. Then a example is given to verify the validity of the theoretical results. 相似文献
13.
Pinning-controlled synchronization of complex networks with bounded or unbounded synchronized regions
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This paper studies pinning-controlled synchronization of complex
networks with bounded or unbounded synchronized regions. To study a
state-feedback pinning-controlled network with N nodes, it first
converts the controlled network to an extended network of N+1
nodes without controls. It is shown that the controlled
synchronizability of the given network is determined by the real
part of the smallest nonzero eigenvalue of the coupling matrix of
its extended network when the synchronized region is unbounded; but
it is determined by the ratio of the real parts of the largest and
the smallest nonzero eigenvalues of the coupling matrix when the
synchronized region is bounded. Both theoretical analysis and
numerical simulation show that the portion of controlled nodes has
no critical values when the synchronized region is unbounded, but it
has a critical value when the synchronized region is bounded. In the
former case, therefore, it is possible to control the network to
achieve synchronization by pinning only one node. In the latter
case, the network can achieve controlled synchronization only when
the portion of controlled nodes is larger than the critical value. 相似文献
14.
Ravasz et al. structured a deterministic model of a geometrically growing network to describe metabolic networks. Inspired by the model of Ravasz et al., a random model of a geometrically growing network is proposed. It is a model of copying nodes continuously and can better describe metabolic networks than the model of Ravasz et al. Analysis shows that the analytic method based on uniform distributions (i.e., Barabási-Albert method) is not suitable for the analysis of the model and the simulation process is beyond computing power owing to its geometric growth mechanism. The model can be better analyzed by the Poisson process. Results show that the model is scale-free with a self-similarity degree exponent, which is dependent on the common ratio of the growth process and similar to that of fractal networks. 相似文献
15.
A strategic collective decision model is introduced to investigate the role of decision transmission mechanism and interaction networks in determining the collective decision dynamics. Assuming that agents are located in a scale-free network and their decisions are interdependent of each other. In our model, it is found that the effective decision transmission rate λ↑- exists a threshold λ↑-c = 1, which marks the transition between the two regimes, i.e. the decision spreading and the decision disappearing in the population. Furthermore, λ↑- is mainly determined by the decision transmission mechanism and interaction network‘s topology. 相似文献
16.
Recent progresses in the protein regulatory network of budding yeast Saccharomyces cerevisiae have provided a global picture of its protein network for further dynamical research. We simplify and modularize the protein regulatory networks in yeast nucleus, and study the dynamical properties of the core 37-node network by a Boolean network model, especially the evolution steps and final fixed points. Our simulation results show that the number of fixed points N(k) for a given size of the attraction basin k obeys a power-law distribution N(k) χ k^-2.024. The yeast network is more similar to a scale-free network than a random network in the above dynamical properties. 相似文献
17.
We propose a new modularity criterion in complex networks, called the unifying modularity q which is independent of the number of partitions. It is shown that, for a given network, the relationship between the upper limit of Q and the number of the partitions, k, is sup(Qk) = (k - 1)/k. Since the range of Q for each partition number is inconsistent, we try to extend the concept Q to unifying modularity q, which is independent of the number of partitions. Subsequently, we indicate that it is more accurately to determine the number of partitions by using unifying modularity q than Q. 相似文献
18.
We study the effects of degree correlations on the evolution of cooperation in the prisoner's dilemma game with individuals located on two types of positively correlated networks. It is shown that the positive degree correlation can either promote or inhibit the emergence of cooperation depending on network configurations. Furthermore, we investigate the probability to cooperate as a function of connectivity degree, and find that high-degree individuals generally have a higher tendency to cooperate. Finally, it is found that small-degree individuals usually change their strategy more frequently, and such change is shown to be unfavourable to cooperation for both kinds of networks. 相似文献
19.
LI Ke-Ping GAO Zi-You 《理论物理通讯》2008,50(10):1013-1016
In complex networks, network modules play a center role, which carry out a key function. In this paper, we introduce the spatial correIation function to describe the relationships among the network modules. Our focus is to investigate how the network modules evolve, and what the evolution properties of the modules are. In order to test the proposed method, as the examples, we use our method to analyze and discuss the ER random network and scale-free network. Rigorous analysis of the existing data shows that the introduced correlation function is suitable for describing the evolution properties of network modules. Remarkably, the numerical simulations indicate that the ER random network and scale-free network have different evolution properties. 相似文献
20.
Assortative/disassortative mixing is an important topological property of a network. A network is called assortative mixing if the nodes in the network tend to connect to their connectivity peers, or disassortative mixing if nodes with low degrees are more likely to connect with high-degree nodes. We have known that biological networks such as protein-protein interaction networks (PPI), gene regulatory networks, and metabolic networks tend to be disassortative. On the other hand, in biological evolution, duplication and divergence are two fundamental processes. In order to make the relationship between the property of disassortative mixing and the two basic biological principles clear and to study the cause of the disassortative mixing property in biological networks, we present a random duplication model and an anti-preference duplication model. Our results show that disassortative mixing networks can be obtained by both kinds of models from uncorrelated initial networks. Moreover, with the growth of the network size, the disassortative mixing property becomes more obvious. 相似文献