4,306 research outputs found
Laser Chimeras as a paradigm for multi-stable patterns in complex systems
Chimera is a rich and fascinating class of self-organized solutions developed
in high dimensional networks having non-local and symmetry breaking coupling
features. Its accurate understanding is expected to bring important insight in
many phenomena observed in complex spatio-temporal dynamics, from living
systems, brain operation principles, and even turbulence in hydrodynamics. In
this article we report on a powerful and highly controllable experiment based
on optoelectronic delayed feedback applied to a wavelength tunable
semiconductor laser, with which a wide variety of Chimera patterns can be
accurately investigated and interpreted. We uncover a cascade of higher order
Chimeras as a pattern transition from N to N - 1 clusters of chaoticity.
Finally, we follow visually, as the gain increases, how Chimera is gradually
destroyed on the way to apparent turbulence-like system behaviour.Comment: 7 pages, 6 figure
Dynamical Systems, Stability, and Chaos
In this expository and resources chapter we review selected aspects of the
mathematics of dynamical systems, stability, and chaos, within a historical
framework that draws together two threads of its early development: celestial
mechanics and control theory, and focussing on qualitative theory. From this
perspective we show how concepts of stability enable us to classify dynamical
equations and their solutions and connect the key issues of nonlinearity,
bifurcation, control, and uncertainty that are common to time-dependent
problems in natural and engineered systems. We discuss stability and
bifurcations in three simple model problems, and conclude with a survey of
recent extensions of stability theory to complex networks.Comment: 28 pages, 10 figures. 26/04/2007: The book title was changed at the
last minute. No other changes have been made. Chapter 1 in: J.P. Denier and
J.S. Frederiksen (editors), Frontiers in Turbulence and Coherent Structures.
World Scientific Singapore 2007 (in press
Almost automorphic delayed differential equations and Lasota-Wazewska model
Existence of almost automorphic solutions for abstract delayed differential
equations is established. Using ergodicity, exponential dichotomy and Bi-almost
automorphicity on the homogeneous part, sufficient conditions for the existence
and uniqueness of almost automorphic solutions are given.Comment: 16 page
Persistence of nonautonomous logistic system with time-varying delays and impulsive perturbations
In this paper, we develop the impulsive control theory to nonautonomous logistic system with time-varying delays. Some sufficient conditions ensuring the persistence of nonautonomous logistic system with time-varying delays and impulsive perturbations are derived. It is shown that the persistence of the considered system is heavily dependent on the impulsive perturbations. The proposed method of this paper is completely new. Two examples and the simulations are given to illustrate the proposed method and results
Coupled logistic maps and non-linear differential equations
We study the continuum space-time limit of a periodic one dimensional array
of deterministic logistic maps coupled diffusively. First, we analyse this
system in connection with a stochastic one dimensional Kardar-Parisi-Zhang
(KPZ) equation for confined surface fluctuations. We compare the large-scale
and long-time behaviour of space-time correlations in both systems. The dynamic
structure factor of the coupled map lattice (CML) of logistic units in its deep
chaotic regime and the usual d=1 KPZ equation have a similar temporal stretched
exponential relaxation. Conversely, the spatial scaling and, in particular, the
size dependence are very different due to the intrinsic confinement of the
fluctuations in the CML. We discuss the range of values of the non-linear
parameter in the logistic map elements and the elastic coefficient coupling
neighbours on the ring for which the connection with the KPZ-like equation
holds. In the same spirit, we derive a continuum partial differential equation
governing the evolution of the Lyapunov vector and we confirm that its
space-time behaviour becomes the one of KPZ. Finally, we briefly discuss the
interpretation of the continuum limit of the CML as a
Fisher-Kolmogorov-Petrovsky-Piscounov (FKPP) non-linear diffusion equation with
an additional KPZ non-linearity and the possibility of developing travelling
wave configurations.Comment: 23 page
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