1,126 research outputs found
Comment on ``Intermittent Synchronization in a Pair of Coupled Chaotic Pendula"
The main aim of this comment is to emphasize that the conditional Lyapunov
exponents play an important role in distinguishing between intermittent and
persistent synchronization, when the analytic criteria for asymptotic stability
are not uniformly obeyed.Comment: 2 pages, RevTeX 4, 1 EPS figur
Enhancing Synchrony in Chaotic Oscillators by Dynamic Relaying
In a chain of mutually coupled oscillators, the coupling threshold for
synchronization between the outermost identical oscillators decreases when a
type of impurity (in terms of parameter mismatch) is introduced in the inner
oscillator(s). The outer oscillators interact indirectly via dynamic relaying,
mediated by the inner oscillator(s). We confirm this enhancing of critical
coupling in the chaotic regimes of R\"ossler system in absence of coupling
delay and in Mackey-Glass system with delay coupling. The enhancing effect is
experimentally verified in electronic circuit of R\"ossler oscillators.Comment: 4 pages, 9 figure
Ensemble averageability in network spectra
The extreme eigenvalues of connectivity matrices govern the influence of the
network structure on a number of network dynamical processes. A fundamental
open question is whether the eigenvalues of large networks are well represented
by ensemble averages. Here we investigate this question explicitly and validate
the concept of ensemble averageability in random scale-free networks by showing
that the ensemble distributions of extreme eigenvalues converge to peaked
distributions as the system size increases. We discuss the significance of this
result using synchronization and epidemic spreading as example processes.Comment: 4 pages, 4 figure
A Unified Approach to Attractor Reconstruction
In the analysis of complex, nonlinear time series, scientists in a variety of
disciplines have relied on a time delayed embedding of their data, i.e.
attractor reconstruction. The process has focused primarily on heuristic and
empirical arguments for selection of the key embedding parameters, delay and
embedding dimension. This approach has left several long-standing, but common
problems unresolved in which the standard approaches produce inferior results
or give no guidance at all. We view the current reconstruction process as
unnecessarily broken into separate problems. We propose an alternative approach
that views the problem of choosing all embedding parameters as being one and
the same problem addressable using a single statistical test formulated
directly from the reconstruction theorems. This allows for varying time delays
appropriate to the data and simultaneously helps decide on embedding dimension.
A second new statistic, undersampling, acts as a check against overly long time
delays and overly large embedding dimension. Our approach is more flexible than
those currently used, but is more directly connected with the mathematical
requirements of embedding. In addition, the statistics developed guide the user
by allowing optimization and warning when embedding parameters are chosen
beyond what the data can support. We demonstrate our approach on uni- and
multivariate data, data possessing multiple time scales, and chaotic data. This
unified approach resolves all the main issues in attractor reconstruction.Comment: 22 pages, revised version as submitted to CHAOS. Manuscript is
currently under review. 4 Figures, 31 reference
Synchronization of Time-Continuous Chaotic Oscillators
Considering a system of two coupled identical chaotic oscillators, the paper first establishes the conditions of transverse stability for the fully synchronized chaotic state. Periodic orbit threshold theory is applied to determine the bifurcations through which low-periodic orbits embedded in the fully synchronized state lose their transverse stability, and the appearance of globally and locally riddled basins of attraction is discussed, respectively, in terms of the subcritical, supercritical nature of the riddling bifurcations. We show how the introduction of a small parameter mismatch between the interacting chaotic oscillators causes a shift of the synchronization manifold. The presence of a coupling asymmetry is found to lead to further modifications of the destabilization process. Finally, the paper considers the problem of partial synchronization in a system of four coupled Rössler oscillators
Intermittent generalized synchronization in unidirectionally coupled chaotic oscillators
A new behavior type of unidirectionally coupled chaotic oscillators near the
generalized synchronization transition has been detected. It has been shown
that the generalized synchronization appearance is preceded by the intermitted
behavior: close to threshold parameter value the coupled chaotic systems
demonstrate the generalized synchronization most of the time, but there are
time intervals during which the synchronized oscillations are interrupted by
non-synchronous bursts. This type of the system behavior has been called
intermitted generalized synchronization (IGS) by analogy with intermitted lag
synchronization (ILS) [Phys. Rev. E \textbf{62}, 7497 (2000)].Comment: 8 pages, 5 figures, using epl.cls; published in Europhysics Letters.
70, 2 (2005) 169-17
Transition from anticipatory to lag synchronization via complete synchronization in time-delay systems
The existence of anticipatory, complete and lag synchronization in a single
system having two different time-delays, that is feedback delay and
coupling delay , is identified. The transition from anticipatory to
complete synchronization and from complete to lag synchronization as a function
of coupling delay with suitable stability condition is discussed. The
existence of anticipatory and lag synchronization is characterized both by the
minimum of similarity function and the transition from on-off intermittency to
periodic structure in laminar phase distribution.Comment: 14 Pages and 12 Figure
Synchronization and directed percolation in coupled map lattices
We study a synchronization mechanism, based on one-way coupling of
all-or-nothing type, applied to coupled map lattices with several different
local rules. By analyzing the metric and the topological distance between the
two systems, we found two different regimes: a strong chaos phase in which the
transition has a directed percolation character and a weak chaos phase in which
the synchronization transition occurs abruptly. We are able to derive some
analytical approximations for the location of the transition point and the
critical properties of the system.
We propose to use the characteristics of this transition as indicators of the
spatial propagation of chaoticity.Comment: 12 pages + 12 figure
Priority-Based Distributed Coordination for Heterogeneous Multi-Robot Systems with Realistic Assumptions
A standing challenge in current intralogistics is to reliably, effectively, yet safely coordinate large-scale, heterogeneous multi-robot fleets without posing constraints on the infrastructure or unrealistic assumptions on robots. A centralized approach, proposed by some of the authors in prior work, allows to overcome these limitations with medium-scale fleets (i.e., tens of robots). With the aim of scaling to hundreds of robots, in this article we explore a decentralized variant of the same approach. The proposed framework maintains the key features of the original approach, namely, ensuring safety despite uncertainties on robot motions, and generality with respect to robot platforms, motion planners and controllers. We include considerations on liveness and report solutions to prevent or recover from deadlocks in specific situations. We validate the approach empirically in simulation with large, heterogeneous multi-robot fleets (with up to 100 robots) operating in both benchmark and realistic environments
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