Showing papers by "Stefano Boccaletti published in 2004"
TL;DR: Despite being absolutely stable, the synchronization manifold is unstable to propagating perturbations and its stability properties are studied to draw a qualitative and quantitative comparison with the convective instabilities typical of spatially extended systems.
Abstract: We study the stability properties of anticipating synchronization in an open chain of unidirectionally coupled identical chaotic oscillators. Despite being absolutely stable, the synchronization manifold is unstable to propagating perturbations. We analyze and characterize such instabilities drawing a qualitative and quantitative comparison with the convective instabilities typical of spatially extended systems.
24 citations
TL;DR: The consequences induced by the presence of asymmetries in the coupling scheme on the synchronization process of a pair of one-dimensional fields obeying complex Ginzburg-Landau equations and it is shown that defects tend to anchor one system to the other.
Abstract: In a recent paper [Phys. Rev. Lett. 91, 064103 (2003)]] we described the effects of asymmetric coupling configurations on the synchronization of spatially extended systems. In this paper, we report the consequences induced by the presence of asymmetries in the coupling scheme on the synchronization process of a pair of one-dimensional fields obeying complex Ginzburg-Landau equations. While synchronization always occurs for large enough coupling strengths, asymmetries have the effect of enhancing synchronization and play a crucial role in setting the threshold for the appearance of the synchronized dynamics, as well as in selecting the statistical and dynamical properties of the synchronized motion. We analyze the process of synchronization in the presence of asymmetries when the dynamics is affected by the presence of phase singularities, and show that defects tend to anchor one system to the other. In addition, asymmetry controls the number of synchronized defects that are present in the dynamics. Possible consequences of such asymmetry induced effects in biological and natural systems are discussed.
18 citations
TL;DR: This work demonstrates targeting and control over spatiotemporal chaos in an optical feedback loop experiment by means of a two dimensional space extended perturbation field driven by an interfaced computer.
Abstract: We demonstrate targeting and control over spatiotemporal chaos in an optical feedback loop experiment. Different stationary target patterns are stabilized in real time by means of a two dimensional space extended perturbation field driven by an interfaced computer and applied in real space to a liquid crystal display device inserted within a control optical loop. The flexibility of the system in switching between different target patterns is also demonstrated.
17 citations
TL;DR: The dynamics of a closed chain of unidirectionally coupled oscillators in a regime of homoclinic chaos show analogies with the experimental behavior of a single chaotic laser subjected to a delayed feedback.
Abstract: We numerically investigate the dynamics of a closed chain of unidirectionally coupled oscillators in a regime of homoclinic chaos. The emerging synchronization regimes show analogies with the experimental behavior of a single chaotic laser subjected to a delayed feedback.
13 citations
TL;DR: Experimental evidence is given that a delayed feedback control strategy is able to efficiently enhance the coherence of an experimental self-sustained chaotic oscillator obtained from a CO2 laser with electro-optical feedback.
Abstract: We give experimental evidence that a delayed feedback control strategy is able to efficiently enhance the coherence of an experimental self-sustained chaotic oscillator obtained from a CO2 laser with electro-optical feedback. We demonstrate that coherence control is achieved for various choices of the delay time in the feedback control, including values that would lead to the stabilization of an unstable periodic orbit embedded within the chaotic attractor. The relationship between the two processes is discussed.
13 citations
TL;DR: This work studies the occurrence of physically observable phase locked states between chaotic oscillators and rotors in which the frequencies of the coupled systems are irrationally related.
Abstract: We study the occurrence of physically observable phase locked states between chaotic oscillators and rotors in which the frequencies of the coupled systems are irrationally related For two chaotic oscillators, the phenomenon occurs as a result of a coupling term which breaks the $2\ensuremath{\pi}$ invariance in the phase equations In the case of rotors, a coupling term in the angular velocities results in very long times during which the coupled systems exhibit alternatively irrational phase synchronization and random phase diffusion The range of parameters for which the phenomenon occurs contains an open set, and is thus physically observable
12 citations
TL;DR: The bifurcation scenario leading to chaotic states of an epidemiological disease spreading within a complex network of individuals is described, and the relevance of the observed chaotic dynamics for the description of the spreading mechanisms of epidemics inside complex networks is discussed.
Abstract: We explore the dynamics of an epidemiological disease spreading
within a complex network of individuals. The local behavior of the epidemics is
modelled by means of an excitable dynamics, and the individuals are connected
in the network through a weighted small-world wiring. The global behavior of
the epidemics can have stationary as well as chaotic states, depending upon
the probability of substituting short-range with long-range interactions. We
describe the bifurcation scenario leading to such latter states, and discuss the
relevance of the observed chaotic dynamics for the description of the spreading
mechanisms of epidemics inside complex networks.
11 citations
TL;DR: Evidence of frequency entrainment of dominant peaks in the chaotic spectra of two coupled chaotic nonautonomous oscillators is given, characterized by the vanishing of a previously positive Lyapunov exponent in the spectrum.
Abstract: We give evidence of frequency entrainment of dominant peaks in the chaotic spectra of two coupled chaotic nonautonomous oscillators. At variance with the autonomous case, the phenomenon is here characterized by the vanishing of a previously positive Lyapunov exponent in the spectrum, which takes place for a broad range of the coupling strength parameter. Such a state is studied also for the case of chaotic oscillators with ill-defined phases due to the absence of a unique center of rotation. Different phase synchronization indicators are used to circumvent this difficulty.
11 citations
TL;DR: Application to a pair of interacting Rössler oscillators shows that the method is able to quantify the number of dynamical configurations where a local prediction task is possible, as well as in the absence of global synchronization features.
Abstract: We introduce a technique to detect and quantify local functional dependencies between coupled chaotic systems. The method estimates the fraction of locally synchronized configurations, in a pair of signals with an arbitrary state of global synchronization. Application to a pair of interacting Rossler oscillators shows that our method is able to quantify the number of dynamical configurations where a local prediction task is possible, as well as in the absence of global synchronization features.
8 citations
TL;DR: The technique recovers the synchronization diagram of the experimental system from only few measurement data sets, thus allowing the prediction of the regime of phase synchronization as well as nonsynchronization in a broad parameter space of forcing frequency and amplitude without further experiments.
Abstract: An approach is presented for the reconstruction of phase synchronization phenomena in a chaotic CO2 laser from experimental data. We analyze this laser system in a regime able to phase synchronize with a weak sinusoidal forcing. Our technique recovers the synchronization diagram of the experimental system from only few measurement data sets, thus allowing the prediction of the regime of phase synchronization as well as nonsynchronization in a broad parameter space of forcing frequency and amplitude without further experiments.
6 citations
TL;DR: The conditions for the existence of heteroclinic connections between the transverse modes of a CO2 laser whose setup has a perfect cylindrical symmetry are discussed by symmetry arguments for the cases of three, four and five interacting modes.
Abstract: The conditions for the existence of heteroclinic connections between the transverse modes of a CO2 laser whose setup has a perfect cylindrical symmetry are discussed by symmetry arguments for the cases of three, four and five interacting modes. Explicit conditions for the parameters are derived, which can guide observation of such phenomena.
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TL;DR: This work implements a mean-field multiplicative coupling among first-neighbor nodes that could be a naive model for the wakening and sleeping of a brain-like system, i.e., a multi-component system with two different dynamical behaviors.
Abstract: A network with local dynamics of logistic type is considered. We implement a mean-field multiplicative coupling among first-neighbor nodes. When the coupling parameter is small the dynamics is dissipated and there is no activity: the network is {\it turned off}. For a critical value of the coupling a non-null stable synchronized state, which represents a {\it turned on} network, emerges. This global bifurcation is independent of the network topology. We characterize the bistability of the system by studying how to perform the transition, which now is topology dependent, from the active state to that with no activity, for the particular case of a scale free network. This could be a naive model for the {\it wakening} and {\it sleeping} of a brain-like system.
14 Dec 2004
TL;DR: In this article, the phase synchronization diagram of a chaotic CO2 laser was reconstructed from only few measurement data sets, thus allowing the prediction of the regime of phase synchronization as well as non-synchronization in a broad parameter space of forcing frequency and amplitude without further experiments.
Abstract: A novel approach is presented for the reconstruction of phase synchronization phenomena in a chaotic CO2 laser from experimental data. We analyze this laser system in a regime of homoclinic chaos, which is able to phase synchronize with a weak sinusoidal forcing. Our technique recovers the synchronization diagram of the experimental system from only few measurement data sets, thus allowing the prediction of the regime of phase synchronization as well as non‐synchronization in a broad parameter space of forcing frequency and amplitude without further experiments.