共查询到20条相似文献,搜索用时 15 毫秒
1.
Natural river networks exhibit regular scaling laws in their topological organization. Here, we investigate whether these
scaling laws are unique characteristics of river networks or can be applicable to general binary tree networks. We generate
numerous binary trees, ranging from purely ordered trees to completely random trees. For each generated binary tree, we analyze
whether the tree exhibits any scaling property found in river networks, i.e., the power-laws in the size distribution, the
length distribution, the distance-load relationship, and the power spectrum of width function. We found that partially random
trees generated on the basis of two distinct types of deterministic trees, i.e., deterministic critical and supercritical
trees, show contrasting characteristics. Partially random trees generated on the basis of deterministic critical trees exhibit
all power-law characteristics investigated in this study with their fitted exponents close to the values observed in natural
river networks over a wide range of random-degree. On the other hand, partially random trees generated on the basis of deterministic
supercritical trees rarely follow scaling laws of river networks. 相似文献
2.
We study the synchronization of coupled phase oscillators in random complex networks. The topology of the networks is assumed to be vary over time. Here we mainly study the onset of global phase synchronization when the topology switches rapidly over time. We find that the results are, to some extent, different from those in deterministic situations. In particular, the synchronizability of coupled oscillators can be enhanced in ER networks and scale-free networks under fast switching, while in stochastic small-world networks such enhancement is not significant. 相似文献
3.
Z.-G. Huang X.-J. Xu Z.-X. Wu Y.-H. Wang 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,51(4):549-553
We carry out comparative studies of random walks on deterministic
Apollonian networks (DANs) and random Apollonian networks (RANs).
We perform computer simulations for the mean first-passage time,
the average return time, the mean-square displacement, and the
network coverage for the unrestricted random walk. The diffusions
both on DANs and RANs are proved to be sublinear. The effects of
the network structure on the dynamics and the search efficiencies
of walks with various strategies are also discussed. Contrary to
intuition, it is shown that the self-avoiding random walk, which
has been verified as an optimal local search strategy in networks,
is not the best strategy for the DANs in the large size limit. 相似文献
4.
Cheoljun Eom 《Physica A》2007,383(1):139-146
The stock market has been known to form homogeneous stock groups with a higher correlation among different stocks according to common economic factors that influence individual stocks. We investigate the role of common economic factors in the market in the formation of stock networks, using the arbitrage pricing model reflecting essential properties of common economic factors. We find that the degree of consistency between real and model stock networks increases as additional common economic factors are incorporated into our model. Furthermore, we find that individual stocks with a large number of links to other stocks in a network are more highly correlated with common economic factors than those with a small number of links. This suggests that common economic factors in the stock market can be understood in terms of deterministic factors. 相似文献
5.
We investigated the topological properties of stock networks constructed by a minimal spanning tree. We compared the original stock network with the estimated network; the original network is obtained by the actual stock returns, while the estimated network is the correlation matrix created by random matrix theory. We found that the consistency between the two networks increases as more eigenvalues are considered. In addition, we suggested that the largest eigenvalue has a significant influence on the formation of stock networks. 相似文献
6.
Zhongzhi Zhang Shuigeng Zhou Yi Qi Jihong Guan 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,63(4):507-513
The uniform recursive tree (URT) is one of the most important models and has been successfully applied to many fields. Here
we study exactly the topological characteristics and spectral properties of the Laplacian matrix of a deterministic uniform
recursive tree, which is a deterministic version of URT. Firstly, from the perspective of complex networks, we determine the
main structural characteristics of the deterministic tree. The obtained vigorous results show that the network has an exponential
degree distribution, small average path length, power-law distribution of node betweenness, and positive degree-degree correlations.
Then we determine the complete Laplacian spectra (eigenvalues) and their corresponding eigenvectors of the considered graph.
Interestingly, all the Laplacian eigenvalues are distinct. 相似文献
7.
Z.-Z. Zhang S.-G. Zhou T. Zou 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,56(3):259-271
In this paper, firstly, we study analytically the topological
features of a family of hierarchical lattices (HLs) from the view
point of complex networks. We derive some basic properties of HLs
controlled by a parameter q: scale-free degree distribution with
exponent γ=2+ln 2/(ln q), null clustering
coefficient, power-law behavior of grid coefficient, exponential
growth of average path length (non-small-world), fractal scaling
with dimension dB=ln (2q)/(ln 2), and disassortativity.
Our results show that scale-free networks are not always
small-world, and support the conjecture that self-similar scale-free
networks are not assortative. Secondly, we define a deterministic
family of graphs called small-world hierarchical lattices (SWHLs).
Our construction preserves the structure of hierarchical lattices,
including its degree distribution, fractal architecture, clustering
coefficient, while the small-world phenomenon arises. Finally, the
dynamical processes of intentional attacks and collective
synchronization are studied and the comparisons between HLs and
Barabási-Albert (BA) networks as well as SWHLs are shown. We
find that the self-similar property of HLs and SWHLs significantly
increases the robustness of such networks against targeted damage on
hubs, as compared to the very vulnerable non fractal BA networks,
and that HLs have poorer synchronizability than their counterparts
SWHLs and BA networks. We show that degree distribution of
scale-free networks does not suffice to characterize their
synchronizability, and that networks with smaller average path
length are not always easier to synchronize. 相似文献
8.
The concept of edge weight provides additional depth for describing and adjusting the properties of networks. Redistribution of edge weight can effectively change the properties of networks even though the corresponding binary topology remains unchanged. Based on regular networks with initially homogeneous dissimilarity weights, random redistribution of edge weight can be enough to induce small world phenomena. The effects of random weight redistribution on both static properties and dynamical models of networks are investigated. The results reveal that randomization of weight can enhance the ability of synchronization of chaotic systems dramatically. 相似文献
9.
J. Živković B. Tadić N. Wick S. Thurner 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,50(1-2):255-258
We analyze gene expression time-series data of yeast (S. cerevisiae) measured along two full cell-cycles. We quantify these data by using
q-exponentials, gene
expression ranking and a temporal mean-variance analysis.
We construct gene interaction networks based on correlation coefficients
and study the formation of the corresponding giant components
and minimum spanning trees.
By coloring genes according to their cell function we find
functional clusters in the correlation networks and functional branches
in the associated trees. Our results suggest that a percolation point of functional clusters can be identified on these gene
expression correlation networks. 相似文献
10.
In this paper, we propose an evolving Sierpinski gasket, based on which we establish a model of evolutionary Sierpinski networks (ESNs) that unifies deterministic Sierpinski network [Z.Z. Zhang, S.G. Zhou, T. Zou, L.C. Chen, J.H. Guan, Eur. Phys. J. B 60 (2007) 259] and random Sierpinski network [Z.Z. Zhang, S.G. Zhou, Z. Su, T. Zou, J.H. Guan, Eur. Phys. J. B 65 (2008) 141] to the same framework. We suggest an iterative algorithm generating the ESNs. On the basis of the algorithm, some relevant properties of presented networks are calculated or predicted analytically. Analytical solution shows that the networks under consideration follow a power-law degree distribution, with the distribution exponent continuously tuned in a wide range. The obtained accurate expression of clustering coefficient, together with the prediction of average path length reveals that the ESNs possess small-world effect. All our theoretical results are successfully contrasted by numerical simulations. Moreover, the evolutionary prisoner’s dilemma game is also studied on some limitations of the ESNs, i.e., deterministic Sierpinski network and random Sierpinski network. 相似文献
11.
Chinese is spoken by the largest number of people in the world, and it is regarded as one of the most important languages. In this paper, we explore the statistical properties of Chinese language networks (CLNs) within the framework of complex network theory. Based on one of the largest Chinese corpora, i.e. People’s Daily Corpus, we construct two networks (CLN1 and CLN2) from two different respects, with Chinese words as nodes. In CLN1, a link between two nodes exists if they appear next to each other in at least one sentence; in CLN2, a link represents that two nodes appear simultaneously in a sentence. We show that both networks exhibit small-world effect, scale-free structure, hierarchical organization and disassortative mixing. These results indicate that in many topological aspects Chinese language shapes complex networks with organizing principles similar to other previously studied language systems, which shows that different languages may have some common characteristics in their evolution processes. We believe that our research may shed some new light into the Chinese language and find some potentially significant implications. 相似文献
12.
We propose a new concept, two-step degree. Defining it as the capacity of a node of complex networks, we establish a novel capacity-load model of cascading failures of complex networks where the capacity of nodes decreases during the process of cascading failures. For scale-free networks, we find that the average two-step degree increases with the increase of the heterogeneity of the degree distribution, showing that the average two- step degree can be used for measuring the heterogeneity of the degree distribution of complex networks. In addition, under the condition that the average degree of a node is given, we can design a scale-free network with the optimal robustness to random failures by maximizing the average two-step degree. 相似文献
13.
In this work we present a model of an air transportation traffic system from the complex network modelling viewpoint. In the network, every node corresponds to a given airport, and two nodes are connected by means of flight routes. Each node is weighted according to its load capacity, and links are weighted according to the Euclidean distance that separates each pair of nodes. Local rules describing the behaviour of individual nodes in terms of the surrounding flow have been also modelled, and a random network topology has been chosen in a baseline approach. Numerical simulations describing the diffusion of a given number of agents (aircraft) in this network show the onset of a jamming transition that distinguishes an efficient regime with null amount of airport queues and high diffusivity (free phase) and a regime where bottlenecks suddenly take place, leading to a poor aircraft diffusion (congested phase). Fluctuations are maximal around the congestion threshold, suggesting that the transition is critical. We then proceed by exploring the robustness of our results in neutral random topologies by embedding the model in heterogeneous networks. Specifically, we make use of the European air transportation network formed by 858 airports and 11 170 flight routes connecting them, which we show to be scale-free. The jamming transition is also observed in this case. These results and methodologies may introduce relevant decision-making procedures in order to optimize the air transportation traffic. 相似文献
14.
In this paper we construct networks for music and attempt to compose music artificially. Networks are constructed with nodes and edges corresponding to musical notes and their co-occurring connections. We analyze classical music from Bach, Mozart, Chopin, as well as other types of music such as Chinese pop music. We observe remarkably similar properties in all networks constructed from the selected compositions. We conjecture that preserving the universal network properties is a necessary step in artificial composition of music. Power-law exponents of node degree, node strength and/or edge weight distributions, mean degrees, clustering coefficients, mean geodesic distances, etc. are reported. With the network constructed, music can be composed artificially using a controlled random walk algorithm, which begins with a randomly chosen note and selects the subsequent notes according to a simple set of rules that compares the weights of the edges, weights of the nodes, and/or the degrees of nodes. By generating a large number of compositions, we find that this algorithm generates music which has the necessary qualities to be subjectively judged as appealing. 相似文献
15.
S. Lehmann L. K. Hansen 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,60(1):83-88
We study community structure of networks. We have developed a scheme
for maximizing the modularity Q [Newman and Girvan, Phys. Rev. E 69, 026113 (2004)] based on mean field methods. Further, we have defined a simple family of random networks with community structure;
we understand the behavior of
these networks analytically. Using these networks, we show how the
mean field methods display better performance than previously known
deterministic methods for optimization of Q. 相似文献
16.
We numerically investigate the effect of four kinds of partial attacks of multiple targets on the Barabási Albert (BA) scale-free network and the Erdos-Rényi (ER) random network. Comparing with the effect of single target complete knockout we find that partial attacks of multiple targets may produce an effect higher than the complete knockout of a single target on both BA scale-free network and ER random network. We also find that the BA scale-free network seems to be more susceptible to multi-target partial attacks than the ER random network. 相似文献
17.
Xin Zhang 《Physica A》2009,388(17):3657-3666
Due to their complexity, real dynamic systems are widely regarded as operating on the boundary between order and chaos. Therefore it is of great interest to determine analytical expressions for this boundary. For random Boolean networks model, a well known critical value of bias is established as , where K is the mean connectivity. Recent research shows, however, that this expression may need to be modified. In this paper, we shall focus on the effects of topology deviation from the random network assumption since the topologies of many real networks are neither pure random nor fully regular Boolean networks. A modification of the critical boundary condition is given with parameters of the degree distribution in the setting of more realistic networks modeled with small world features. 相似文献
18.
How do diverse dynamical patterns arise from the topology of complex networks? We study synchronization dynamics in the cortical brain network of the cat, which displays a hierarchically clustered organization, by modeling each node (cortical area) with a subnetwork of interacting excitable neurons. We find that in the biologically plausible regime the dynamics exhibits a hierarchical modular organization, in particular, revealing functional clusters coinciding with the anatomical communities at different scales. Our results provide insights into the relationship between network topology and functional organization of complex brain networks. 相似文献
19.
A. P. Quayle A. S. Siddiqui S. J.M. Jones 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,50(4):617-630
We propose a model of an underlying mechanism responsible for the formation of assortative mixing in networks between “similar”
nodes or vertices based on generic vertex properties. Existing models focus on a particular type of assortative mixing, such
as mixing by vertex degree, or present methods of generating a network with certain properties, rather than modeling a mechanism
driving assortative mixing during network growth. The motivation is to model assortative mixing by non-topological vertex
properties, and the influence of these non-topological properties on network topology. The model is studied in detail for
discrete and hierarchical vertex properties, and we use simulations to study the topology of resulting networks. We show that
assortative mixing by generic properties directly drives the formation of community structure beyond a threshold assortativity
of r ∼0.5, which in turn influences other topological properties. This direct relationship is demonstrated by introducing
a new measure to characterise the correlation between assortative mixing and community structure in a network. Additionally,
we introduce a novel type of assortative mixing in systems with hierarchical vertex properties, from which a hierarchical
community structure is found to result.
Electronic supplementary material Supplementary Online Material 相似文献
20.
D. Q. Li M. H. Li J. S. Wu Z. R. Di Y. Fan 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,57(4):423-428
In weighted networks, redistribution of link weights can
effectively change the properties of networks, even though the corresponding binary topology remains unchanged. In this paper,
the effects of weight randomization on synchronization of coupled chaotic maps is investigated on regular weighted networks.
The results reveal that synchronizability is enhanced by redistributing of link weights, i.e. coupled maps reach complete
synchronization with lower cost. Furthermore, we show numerically that the
heterogeneity of link weights could improve the complete synchronization on regular weighted networks. 相似文献