共查询到20条相似文献,搜索用时 15 毫秒
1.
N. Gupte B. K. Singh 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,50(1-2):227-230
We study network traffic dynamics in a two dimensional communication
network
with regular nodes and hubs.
If the network experiences heavy message traffic, congestion occurs due
to finite
capacity of the nodes. We discuss strategies to manipulate hub
capacity and hub
connections to relieve congestion and define a coefficient of
betweenness centrality
(CBC), a direct measure of network traffic, which is useful for
identifying hubs which
are most likely to cause congestion. The addition of assortative
connections to hubs
of high CBC relieves congestion very efficiently.
An erratum to this article is available at . 相似文献
2.
M. N. Kuperman M. Ballard F. Laguna 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,50(3):513-520
A model for a dynamic network consisting of changing
local interactions is presented in this work. While the network
maintains solely local connections, certain properties known only
to Small World Networks may be extracted due to the dynamic nature
of the model. At each time step the individuals are grouped into
clusters creating neighborhoods or domains of fully connected
agents. The boundaries of these domains change in time,
corresponding to a situation where the links between individuals
are dynamic only throughout the history of the network. A question
that we pose is whether our model, which maintains a local
structure such that diffusion calculations are possible, might
lead to analytic or conceptual advances for the much more
complicated case of diffusion on a static disordered network that
exhibits the same macroscopic properties as our dynamic
ordered network. To answer this, we compare certain properties
which characterize the dynamic domain network to those of a Small
World Network, and then analyze the diffusion coefficients for
three possible domain mutations. We close with a comparison and
confirmation of previous epidemiological work carried out on
networks. 相似文献
3.
G. Ghoshal M. E.J. Newman 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,58(2):175-184
We consider distributed networks, such as peer-to-peer networks, whose
structure can be manipulated by adjusting the rules by which vertices
enter and leave the network. We focus in particular on degree
distributions and show that, with some mild constraints, it is possible
by a suitable choice of rules to arrange for the network to have any
degree distribution we desire. We also describe a mechanism based on
biased random walks by which appropriate rules could be implemented in
practice. As an example application, we describe and simulate the
construction of a peer-to-peer network optimized to minimize search times
and bandwidth requirements. 相似文献
4.
E. P. Borges D. O. Cajueiro R. F.S. Andrade 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,58(4):469-474
The objective of this study is to design a procedure to
characterize chaotic dynamical systems, in which they are
mapped onto a complex network. The nodes represent the regions of space
visited by the system, while the edges represent the transitions between
these regions. Parameters developed to quantify the properties of complex
networks, including those related to higher order neighbourhoods, are used
in the analysis. The methodology is tested on the logistic map, focusing
on the onset of chaos and chaotic regimes. The corresponding networks were
found to have distinct features that are associated with the particular
type of dynamics that generated them. 相似文献
5.
R. F.S. Andrade J. G.V. Miranda S. T.R. Pinho T. P. Lobão 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,61(2):247-256
A concept of higher order neighborhood in complex networks,
introduced previously [Phys. Rev. E 73, 046101 (2006)], is systematically
explored to investigate larger scale structures in complex networks. The
basic idea is to consider each higher order neighborhood as a network in
itself, represented by a corresponding adjacency matrix, and to settle a
plenty of new parameters in order to obtain a best characterization of the
whole network. Usual network indices are then used to evaluate the
properties of each neighborhood. The identification of high order
neighborhoods is also regarded as intermediary step towards the evaluation
of global network properties, like the diameter, average shortest path
between node, and network fractal dimension. Results for a large number of
typical networks are presented and discussed. 相似文献
6.
L. da F. Costa L. E.C. da Rocha 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,50(1-2):237-242
This work describes how the
formalization of complex network concepts in terms of discrete
mathematics, especially mathematical morphology, allows a series
of generalizations and important results ranging from new
measurements of the network topology to new network growth models.
First, the concepts of node degree and clustering coefficient are
extended in order to characterize not only specific nodes, but any
generic subnetwork. Second, the consideration of distance
transform and rings are used to further extend those concepts in
order to obtain a signature, instead of a single scalar
measurement, ranging from the single node to whole graph scales.
The enhanced discriminative potential of such extended
measurements is illustrated with respect to the identification of
correspondence between nodes in two complex networks, namely a
protein-protein interaction network and a perturbed version of it. 相似文献
7.
G. Xu S. Tsoka L. G. Papageorgiou 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,60(2):231-239
The detection of community structure has been used to reveal the
relationships between individual objects and their groupings in networks.
This paper presents a mathematical programming approach to identify the
optimal community structures in complex networks based on the maximisation
of a network modularity metric for partitioning a network into modules. The
overall problem is formulated as a mixed integer quadratic programming
(MIQP) model, which can then be solved to global optimality using standard
optimisation software. The solution procedure is further enhanced by
developing special symmetry-breaking constraints to eliminate equivalent
solutions. It is shown that additional features such as minimum/maximum
module size and balancing among modules can easily be incorporated in the
model. The applicability of the proposed optimisation-based approach is
demonstrated by four examples. Comparative results with other approaches
from the literature show that the proposed methodology has superior
performance while global optimum is guaranteed. 相似文献
8.
L. Wang F. Du H. P. Dai Y. X. Sun 《The European Physical Journal B - Condensed Matter and Complex Systems》2006,53(3):361-366
A random pseudofractal network (RPN) is generated by a
recursive growing rule. The RPN is of the scale-free feature and
small-world effect. We obtain the theoretical results of power-law
exponent γ=3, clustering coefficient C=3π2-19≈
0.74, and a proof that the mean distance increases no faster than
ln N, where N is the network size. These results agree with
the numerical simulation very well. In particular, we explain the
property of growth and preferential attachment in RPNs. And the
properties of a class of general RPNs are discussed in the end. 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 work, we propose and study a model for the diffusion of congestion in complex networks. According to the proposed model, the level of congestion on each node will be self-organized into the same value. The diffusion of congestion throughout various networks with different topologies is investigated analytically and by numerical tests. The flow fluctuations in complex networks are studied. We recover a power-law scaling relation between the standard deviation and mean flow, which is consistent with the previous studies. Finally, we extend our model by adding two constraints, which may be effective strategies for diffusing the local and the global congestion in complex networks, respectively. 相似文献
11.
F. Nisbach M. Kaiser 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,58(2):185-191
Many networks extent in space, may it be metric (e.g. geographic) or non-metric (ordinal). Spatial network growth, which depends
on the distance between nodes, can generate a wide range of topologies from small-world to linear scale-free networks. However,
networks often lacked multiple clusters or communities. Multiple clusters can be generated, however, if there are time windows
during development. Time windows ensure that regions of the network develop connections at different points in time. This
novel approach could generate small-world but not scale-free networks. The resulting topology depended critically on the overlap
of time windows as well as on the position of pioneer nodes. 相似文献
12.
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
13.
B. Karrer G. Ghoshal 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,62(2):239-245
There has been a considerable amount of interest in recent years on the robustness of networks to failures. Many previous
studies have concentrated on the effects of node and edge removals on the connectivity structure of a static network; the networks are considered to be static in the sense that no compensatory measures are allowed for recovery of
the original structure. Real world networks such as the world wide web, however, are not static and experience a considerable
amount of turnover, where nodes and edges are both added and deleted. Considering degree-based node removals, we examine the
possibility of preserving networks from these types of disruptions. We recover the original degree distribution by allowing
the network to react to the attack by introducing new nodes and attaching their edges via specially tailored schemes. We focus
particularly on the case of non-uniform failures, a subject that has received little attention in the context of evolving
networks. Using a combination of analytical techniques and numerical simulations, we demonstrate how to preserve the exact degree distribution of the studied networks from various forms of attack. 相似文献
14.
S. Singh A. Samal V. Giri S. Krishna N. Raghuram S. Jain 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,57(1):75-80
Biological and social systems have been found to possess
a non-trivial underlying network structure of interacting
components. An important current question concerns the nature of the
evolutionary processes that have led to the observed structural
patterns dynamically. By comparing the metabolic networks of
evolutionarily closeby as well distant species, we present results
on the evolution of these networks over short as well as long time
scales. We observe that the amount of change in the reaction set of
a metabolite across different species is proportional to the degree
of the metabolite, thus providing empirical evidence for a
`proportionate change' mechanism. We find that this evolutionary
process is characterized by a power law with a universal exponent
that is independent of the pair of species compared. 相似文献
15.
A limited resource model of fault-tolerant capability
against cascading failure of complex network 总被引:1,自引:0,他引:1
P. Li B.-H. Wang H. Sun P. Gao T. Zhou 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,62(1):101-104
We propose a novel capacity model for complex networks
against cascading failure. In this model, vertices with both higher
loads and larger degrees should be paid more extra capacities, i.e.
the allocation of extra capacity on vertex i will be proportional
to ki
γ , where ki is the degree of vertex i
and γ > 0 is a free parameter. We have applied this model on
Barabási-Albert network as well as two real transportation
networks, and found that under the same amount of available
resource, this model can achieve better network robustness than
previous models. 相似文献
16.
E. A. Leicht G. Clarkson K. Shedden M. E.J. Newman 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,59(1):75-83
In this paper we examine a number of methods for probing and
understanding the large-scale structure of networks that evolve over
time. We focus in particular on citation networks, networks of
references between documents such as papers, patents, or court cases. We
describe three different methods of analysis, one based on an
expectation-maximization algorithm, one based on modularity optimization,
and one based on eigenvector centrality. Using the network of citations
between opinions of the United States Supreme Court as an example, we
demonstrate how each of these methods can reveal significant structural
divisions in the network and how, ultimately, the combination of all
three can help us develop a coherent overall picture of the network's
shape. 相似文献
17.
F. Greil B. Drossel 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,57(1):109-113
We investigate Threshold Random Boolean Networks with K = 2
inputs per node, which are equivalent to Kauffman networks, with only
part of the canalyzing functions as update functions.
According to the simplest consideration these networks should be
critical but it turns out that they show a rich variety of behaviors,
including periodic and chaotic oscillations.
The analytical results are supported by computer simulations. 相似文献
18.
J. M. Kumpula J. Saramäki K. Kaski J. Kertész 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,56(1):41-45
According to Fortunato and Barthélemy, modularity-based community detection
algorithms have a resolution threshold such that small communities in a large
network are invisible. Here we generalize their work and show that the q-state
Potts community detection method introduced by Reichardt and Bornholdt
also has a resolution threshold. The model contains a parameter by which this threshold can be tuned, but no a priori principle
is known to select the proper value.
Single global optimization criteria do not seem capable for detecting all
communities if their size distribution is broad. 相似文献
19.
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
20.
W. Q. Duan 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,59(2):271-276
Identifying universal patterns in complex economic
systems can reveal the dynamics and organizing principles underlying the
process of system evolution. We investigate the scaling behaviours that have
emerged in the international trade system by describing them as a series of
evolving weighted trade networks. The maximum-flow spanning trees (constructed by maximizing the total
weight of the edges) of these networks exhibit two universal scaling
exponents: (1) topological scaling exponent η = 1.30 and (2) flow
scaling exponent ζ = 1.03. 相似文献