8,559 research outputs found
Robustness of the avalanche dynamics in data packet transport on scale-free networks
We study the avalanche dynamics in the data packet transport on scale-free
networks through a simple model. In the model, each vertex is assigned a
capacity proportional to the load with a proportionality constant . When
the system is perturbed by a single vertex removal, the load of each vertex is
redistributed, followed by subsequent failures of overloaded vertices. The
avalanche size depends on the parameter as well as which vertex triggers
it. We find that there exists a critical value at which the avalanche
size distribution follows a power law. The critical exponent associated with it
appears to be robust as long as the degree exponent is between 2 and 3, and is
close in value to that of the distribution of the diameter changes by single
vertex removal.Comment: 5 pages, 7 figures, final version published in PR
Sandpiles on multiplex networks
We introduce the sandpile model on multiplex networks with more than one type
of edge and investigate its scaling and dynamical behaviors. We find that the
introduction of multiplexity does not alter the scaling behavior of avalanche
dynamics; the system is critical with an asymptotic power-law avalanche size
distribution with an exponent on duplex random networks. The
detailed cascade dynamics, however, is affected by the multiplex coupling. For
example, higher-degree nodes such as hubs in scale-free networks fail more
often in the multiplex dynamics than in the simplex network counterpart in
which different types of edges are simply aggregated. Our results suggest that
multiplex modeling would be necessary in order to gain a better understanding
of cascading failure phenomena of real-world multiplex complex systems, such as
the global economic crisis.Comment: 7 pages, 7 figure
Skeleton and fractal scaling in complex networks
We find that the fractal scaling in a class of scale-free networks originates
from the underlying tree structure called skeleton, a special type of spanning
tree based on the edge betweenness centrality. The fractal skeleton has the
property of the critical branching tree. The original fractal networks are
viewed as a fractal skeleton dressed with local shortcuts. An in-silico model
with both the fractal scaling and the scale-invariance properties is also
constructed. The framework of fractal networks is useful in understanding the
utility and the redundancy in networked systems.Comment: 4 pages, 2 figures, final version published in PR
Complete trails of co-authorship network evolution
The rise and fall of a research field is the cumulative outcome of its
intrinsic scientific value and social coordination among scientists. The
structure of the social component is quantifiable by the social network of
researchers linked via co-authorship relations, which can be tracked through
digital records. Here, we use such co-authorship data in theoretical physics
and study their complete evolutionary trail since inception, with a particular
emphasis on the early transient stages. We find that the co-authorship networks
evolve through three common major processes in time: the nucleation of small
isolated components, the formation of a tree-like giant component through
cluster aggregation, and the entanglement of the network by large-scale loops.
The giant component is constantly changing yet robust upon link degradations,
forming the network's dynamic core. The observed patterns are successfully
reproducible through a new network model
Probing Spin-Charge Relation by Magnetoconductance in One-Dimensional Polymer Nanofibers
Polymer nanofibers are one-dimensional organic hydrocarbon systems containing
conducting polymers where the non-linear local excitations such as solitons,
polarons and bipolarons formed by the electron-phonon interaction were
predicted. Magnetoconductance (MC) can simultaneously probe both the spin and
charge of these mobile species and identify the effects of electron-electron
interactions on these nonlinear excitations. Here we report our observations of
a qualitatively different MC in polyacetylene (PA) and in polyaniline (PANI)
and polythiophene (PT) nanofibers. In PA the MC is essentially zero, but it is
present in PANI and PT. The universal scaling behavior and the zero (finite) MC
in PA (PANI and PT) nanofibers provide evidence of Coulomb interactions between
spinless charged solitons (interacting polarons which carry both spin and
charge)
Scale-free random branching tree in supercritical phase
We study the size and the lifetime distributions of scale-free random
branching tree in which branches are generated from a node at each time
step with probability . In particular, we focus on
finite-size trees in a supercritical phase, where the mean branching number
is larger than 1. The tree-size distribution exhibits a
crossover behavior when ; A characteristic tree size
exists such that for , and for , , where scales as . For , it follows the conventional
mean-field solution, with .
The lifetime distribution is also derived. It behaves as for , and for when branching step , and for all when . The analytic solutions are
corroborated by numerical results.Comment: 6 pages, 6 figure
Network of Econophysicists: a weighted network to investigate the development of Econophysics
The development of Econophysics is studied from the perspective of scientific
communication networks. Papers in Econophysics published from 1992 to 2003 are
collected. Then a weighted and directed network of scientific communication,
including collaboration, citation and personal discussion, is constructed. Its
static geometrical properties, including degree distribution, weight
distribution, weight per degree, and betweenness centrality, give a nice
overall description of the research works. The way we introduced here to
measure the weight of connections can be used as a general one to construct
weighted network.Comment: 6 pages, 7 figure
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