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1.
M. Ponce C. C. Masoller Arturo C. Martí 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,67(1):83-93
We study a network of coupled logistic maps whose interactions occur with a certain distribution of delay times. The local
dynamics is chaotic in the absence of coupling and thus the network is a paradigm of a complex system. There are two regimes
of synchronization, depending on the distribution of delays: when the delays are sufficiently heterogeneous the network synchronizes
on a steady-state (that is unstable for the uncoupled maps); when the delays are homogeneous, it synchronizes in a time-dependent
state (that is either periodic or chaotic). Using two global indicators we quantify the synchronizability on the two regimes,
focusing on the roles of the network connectivity and the topology. The connectivity is measured in terms of the average number
of links per node, and we consider various topologies (scale-free, small-world, star, and nearest-neighbor with and without
a central hub). With weak connectivity and weak coupling strength, the network displays an irregular oscillatory dynamics
that is largely independent of the topology and of the delay distribution. With heterogeneous delays, we find a threshold
connectivity level below which the network does not synchronize, regardless of the network size. This minimum average number
of neighbors seems to be independent of the delay distribution. We also analyze the effect of self-feedback loops and find
that they have an impact on the synchronizability of small networks with large coupling strengths. The influence of feedback,
enhancing or degrading synchronization, depends on the topology and on the distribution of delays. 相似文献
2.
N. Fujiwara J. Kurths 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,69(1):45-49
We employ a spectral decomposition method to
analyze synchronization of a non-identical oscillator network.
We study the case that a small parameter mismatch
of oscillators is characterized by one parameter
and phase synchronization is observed.
We derive a linearized equation for each eigenmode of the coupling matrix.
The parameter mismatch
is reflected on inhomogeneous term in the linearized equation.
We find that the
oscillation of each mode is essentially characterized only by
the eigenvalue of the coupling matrix with a suitable normalization.
We refer to this property as spectral universality,
because it is observed irrespective of network topology.
Numerical results in various network topologies
show good agreement with those based on linearized equation.
This universality is also observed in a system
driven by additive independent Gaussian noise. 相似文献
3.
A. Pitti M. Lungarella Y. Kuniyoshi 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,63(2):239-243
Metastability is a property of systems composed of many interacting parts wherein the parts exhibit simultaneously a tendency
to function autonomously (local segregation) and a tendency to cooperate (global integration). We study anisotropically coupled
map lattices and discover that for specific values of the coupling control parameters the entire system transits to a metastable
regime. We show that this regime manifests a quasi-stable state in which the system can flexibly switch to another such state.
We briefly discuss the relevance of our findings for information processing, functional integration, metastability in the
brain, and phase transitions in complex systems. 相似文献
4.
Y. Liu Z-Y. Sun L-J. An 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,62(4):481-484
Banded spherulite patterns are simulated in two dimensions by means of a
coupled logistic map lattice model. Both target pattern and spiral pattern
which have been proved to be existent experimentally in banded spherulite
are obtained by choosing suitable parameters in the model. The simulation
results also indicate that the band spacing is decreased with the increase
of parameter μ in the logistic map and increased with the increase of
the coupling parameter ε, which is quite similar to the results
in some experiments. Moreover, the relationship between the parameters and
the corresponding patterns is obtained, and the target patterns and spiral
patterns are distinguished for a given group of initial values, which may
guide the study of banded spherulite. 相似文献
5.
N. Kouvaris A. Provata 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,70(4):535-541
Long distance reactive and diffusive coupling is introduced in a spatially extended nonlinear stochastic network of interacting
particles. The network serves as a substrate for Lotka-Volterra dynamics with 3rd order nonlinearities. If the network includes
only local nearest neighbour interactions, the system organizes into a number of local asynchronous oscillators. It is shown
that (a) Introduction of all-to-all coupling in the network leads the system into global, center-type, conservative oscillations
as dictated by the mean-field dynamics. (b) Introduction of reactive coupling to the network leads the system to intermittent
oscillations where the trajectories stick for short times in bounded regions of space, with subsequent jumps between different
bounded regions. (c) Introduction of diffusive coupling to the system does not alter the dynamics for small values of the
diffusive coupling pdiff, while after a critical value pdiff
c the system synchronizes into a limit cycle with specific frequency, deviating non-trivially from the mean-field center-type
behaviour. The frequency of the limit cycle oscillations depends on the reaction rates and on the diffusion coupling. The
amplitude σ of the limit cycle depends on the control parameter pdiff. 相似文献
6.
R. Bonin G. Bertotti C. Serpico I. D. Mayergoyz M. d’Aquino 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,68(2):221-231
An analytical approach is presented for the study of synchronization effects in spin-transfer-driven nanomagnets subjected
to radio-frequency magnetic fields. The conditions are derived and discussed under which the current-induced magnetization
precession is synchronized by the radio-frequency field. Exact analytical results are obtained for the case when the problem
exhibits uniaxial symmetry around the axis perpendicular to the device plane. It is demonstrated that the magnetization dynamics
under nonzero current and nonzero rf field is identical in structure to that under zero current. On this basis, analytical
predictions are obtained for: the existence of phase-locking between current-induced magnetization precession and rf field
oscillations; the frequency pulling effect in proximity of phase locking; the occurrence of hysteresis effects in phase-locking
as a function of the spin-polarized current. The proposed approach is valid for arbitrary rf field amplitude and current intensity. 相似文献
7.
The dynamics of the array consisting of two coupled solid-state lasers with frequency modulations was researched numerically.
Array intensity’s chaotic behavior is predicted when the modulation frequency is low. The physical mechanism of the chaos
is discussed here qualitatively. It was found that not only a harmonic resonance itself but also the duration of the harmonic
resonance long enough is needed for the appearance of the chaos. 相似文献
8.
G. Yan Z. -Q. Fu G. Chen 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,63(4):515-520
We study the consensus dynamics with or without time-delays on directed and undirected de Bruijn graphs. Our results show
that consensus on an undirected de Bruijn graph has a lower converging speed and larger time-delay tolerance in comparison
with that on an undirected scale-free network. Although there is not much difference between the eigenvalue ratios of the
two undirected networks, we found that their dynamical properties are remarkably different; consequently, it is seemingly
more informative to consider the second smallest and the largest eigenvalues separately rather than considering their ratio
in the study of synchronization of a coupled oscillators network. Moreover, our study on directed de Bruijn graphs reveals
that properly setting directions on edges can improve the converging speed and time-delay tolerance simultaneously. 相似文献
9.
R. Donner 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,63(3):349-361
Networks of interacting components are a class of complex systems that has attracted considerable interest over the last decades.
In particular, if the dynamics of the autonomous components is characterised by an oscillatory behaviour, different types
of synchronisation can be observed in dependence on the type and strength of interactions. In this contribution, we study
the transition from non-synchronised to synchronised phase dynamics in complex networks. The most common approach to quantify
the degree of phase synchronisation in such systems is the consideration of measures of phase coherence which are averaged
over all pairs of interacting components. However, this approach implicitly assumes a spatially homogeneous synchronisation process,
which is typically not present in complex networks. As a potential alternative, two novel methods of multivariate phase synchronisation analysis are considered: synchronisation cluster analysis (SCA) and the linear variance decay (LVD)
dimension method. The strengths and weaknesses of the traditional as well as both new approaches are briefly illustrated for
a Kuramoto model with long-range coupling. As a practical application, we study how spatial heterogeneity influences the transition
to phase synchronisation in traffic networks where intersecting material flows are subjected to a self-organised decentralised
control. We find that the network performance and the degree of phase synchronisation are closely related to each other and
decrease significantly in the case of structural heterogeneities. The influences of the different parameters of our control
approach on the synchronisation process are systematically studied, yielding a sequence of Arnold tongues which correspond
to different locking modes. 相似文献
10.
A. Pluchino A. Rapisarda V. Latora 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,65(3):395-402
We have recently introduced [Phys. Rev. E 75, 045102(R) (2007); AIP Conference Proceedings 965, 2007, p. 323] an efficient method for the detection and identification of modules in complex networks, based on the de-synchronization
properties (dynamical clustering) of phase oscillators. In this paper we apply the dynamical clustering tecnique to the identification
of communities of marine organisms living in the Chesapeake Bay food web. We show that our algorithm is able to perform a
very reliable classification of the real communities existing in this ecosystem by using different kinds of dynamical oscillators.
We compare also our results with those of other methods for the detection of community structures in complex networks. 相似文献
11.
M.?Morillo J.?Gómez-Ordó?ez J. M.?Casado J.?Casado-Pascual D.?Cubero 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,69(1):59-64
In this article, we investigate the stochastic resonance
(SR) effect in a finite array of noisy bistable systems with
nearest-neighbor coupling driven by a weak time-periodic driving
force. The array is characterized by a collective variable. By means
of numerical simulations, the signal-to-noise ratio (SNR) and the
gain are estimated as functions of the noise and the interaction
coupling strength. A strong enhancement of the SR phenomenon for
this collective variable in comparison with SR in single unit
bistable systems is observed. Gains larger than unity are obtained
for some parameter values and multi-frequency driving forces,
indicating that the system is operating in a non-linear regime
albeit the smallness of the driving amplitude. The large SNR values
observed are basically due to the fact that the output fluctuations
are small and short lived, in comparison with their typical values
in a linear regime. A non-monotonic behavior of the SNR with the
coupling strength is also obtained. 相似文献
12.
D. A. Kenwright A. Bahraminasab A. Stefanovska P. V. E. McClintock 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,65(3):425-433
We show that the transitions which occur between close orders of synchronization in the cardiorespiratory system are mainly
due to modulation of the cardiac and respiratory processes by low-frequency components. The experimental evidence is derived
from recordings on healthy subjects at rest and during exercise. Exercise acts as a perturbation of the system that alters
the mean cardiac and respiratory frequencies and changes the amount of their modulation by low-frequency oscillations. The
conclusion is supported by numerical evidence based on a model of phase-coupled oscillators, with white noise and lowfrequency
noise. Both the experimental and numerical approaches confirm that low-frequency oscillations play a significant role in the
transitional behavior between close orders of synchronization. 相似文献
13.
C. J. Tessone D. H. Zanette R. Toral 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,62(3):319-326
We study the influence of repulsive interactions on an
ensemble of coupled excitable rotators. We find that a moderate
fraction of repulsive interactions can trigger global firing of the
ensemble. The regime of global firing, however, is suppressed in
sufficiently large systems if the network of repulsive interactions
is fully random, due to self-averaging in its degree distribution.
We thus introduce a model of partially random networks with a broad
degree distribution, where self-averaging due to size growth is
absent. In this case, the regime of global firing persists for large
sizes. Our results extend previous work on the constructive effects
of diversity in the collective dynamics of complex systems. 相似文献
14.
15.
Global synchronization in arrays of coupled networks with one single time-varying delay coupling is investigated in this Letter. A general linear coupled network with a time-varying coupling delay is proposed and its global synchronization is further discussed. Some sufficient criteria are derived based on Lyapunov functional and linear matrix inequality (LMI). It is shown that under one single delay coupling, the synchronized state changes, which is different from the conventional synchronized solution. Moreover, the degree of the nodes and the inner delayed coupling matrix play key roles in the synchronized state. In particular, the derivative of the time-varying delay can be any given value. Finally, numerical simulations are given to illustrate the theoretical results. 相似文献
16.
E. Heinsalu M. Patriarca F. Marchesoni 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,69(1):19-22
We study the effects of the confining conditions on the
occurrence of stochastic resonance (SR) in continuous bistable
systems. We model such systems by means of double-well potentials
that diverge like |x|q for |x|↦∞. For super-harmonic
(hard) potentials with q > 2 the SR peak sharpens with increasing q, whereas for sub-harmonic (soft) potentials, q < 2, it
gets
suppressed. 相似文献
17.
A. D. Chepelianskii A. S. Pikovsky D. L. Shepelyansky 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,60(2):225-229
We show, in a framework of a classical nonequilibrium model,
that rotational angles of electrons moving in two dimensions (2D)
in a perpendicular magnetic field can be synchronized
by an external microwave field whose frequency
is close to the Larmor frequency. The synchronization eliminates
collisions between electrons and thus creates
a regime with zero diffusion corresponding to the zero-resistance states
observed in experiments with high mobility 2D electron gas (2DEG).
For long range Coulomb interactions electrons form a rotating
hexagonal Wigner crystal.
Possible relevance of this effect of
synchronization-induced self-assembly
for planetary rings is discussed. 相似文献
18.
19.
Using a slightly simplified version of the integrate and fire model of a neural network with delay, I study the stability
of the phase-locked state dependent on the coupling between the neurons and especially on a delay time. The coupling between
neurons may be arbitrary. It is shown that the phase-locked state becomes less stable with increasing delay and that relaxation
oscillations occur.
Received 28 December 1999 and Received in final form 13 June 2000 相似文献
20.
D. H. Zanette 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,69(2):269-273
We study the effects of noise on the collective dynamics of an ensemble of coupled phase oscillators whose natural frequencies
are all identical, but whose coupling strengths are not the same all over the ensemble. The intensity of noise can also be
heterogeneous, representing diversity in the individual responses to external fluctuations. We show that the desynchronization
transition induced by noise may be completely suppressed, even for arbitrarily large noise intensities, is the distribution
of coupling strengths decays slowly enough for large couplings. Equivalently, if the response to noise of a sufficiently large
fraction of the ensemble is weak enough, desynchronization cannot occur. The two effects combine with each other when the
response to noise and the coupling strength of each oscillator are correlated. This combination is quantitatively characterized
and illustrated with explicit examples. 相似文献