564 research outputs found
Advection in chaotically time-dependent open flows
The passive advection of tracer panicles is considered in open two-dimensional incompressible flows with chaotic time dependence. As illustrative examples we investigate flows produced by chaotically moving ideal point vortices. The advection problem can be seen as a chaotic scattering process in a chaotically driven Hamiltonian system. Studying the motion of tracer ensembles, we present numerical evidence for the existence of a bounded chaotic set containing infinitely many aperiodic trajectories never leaving the mixing region of the flow. These ensembles converge to filamental patterns which, however, do not follow self-similar scaling. Nevertheless, they possess a fractal dimension after averaging over several finite-time realizations of the flow. We propose random maps as simple models of the phenomenon
A chaotically driven model climate: extreme events and snapshot attractors
In a low-order chaotic global atmospheric circulation model the effects of deterministic chaotic driving are investigated. As a result of driving, peak-over-threshold type extreme events, e. g. cyclonic activity in the model, become more extreme, with increased frequency of recurrence. When the characteristic time of the driving is comparable to that of the undriven system, a resonance effect with amplified variance shows up. For very fast driving we find a reduced enhancement of variance, which is also the case with white noise driving. Snapshot attractors and their natural measures are determined as a function of time, and a resonance effects is also identified. The extreme value statistics of group maxima is found to follow a Weibull distribution
Quantum and classical echoes in scattering systems described by simple Smale horseshoes
We explore the quantum scattering of systems classically described by binary
and other low order Smale horseshoes, in a stage of development where the
stable island associated with the inner periodic orbit is large, but chaos
around this island is well developed. For short incoming pulses we find
periodic echoes modulating an exponential decay over many periods. The period
is directly related to the development stage of the horseshoe. We exemplify our
studies with a one-dimensional system periodically kicked in time and we
mention possible experiments.Comment: 7 pages with 6 reduced quality figures! Please contact the authors
([email protected]) for an original good quality pre-prin
Phase transitions of extended-range probabilistic cellular automata with two absorbing states
We study phase transitions in a long-range one-dimensional cellular automaton
with two symmetric absorbing states. It includes and extends several other
models, like the Ising and Domany-Kinzel ones. It is characterized by a
competing ferromagnetic linear coupling and an antiferromagnetic nonlinear one.
Despite its simplicity, this model exhibits an extremely rich phase diagram. We
present numerical results and mean-field approximations.Comment: New and expanded versio
Bursts in the Chaotic Trajectory Lifetimes Preceding the Controlled Periodic Motion
The average lifetime () it takes for a randomly started trajectory
to land in a small region () on a chaotic attractor is studied. is
an important issue for controlling chaos. We point out that if the region
is visited by a short periodic orbit, the lifetime strongly deviates
from the inverse of the naturally invariant measure contained within that
region (). We introduce the formula that relates
to the expanding eigenvalue of the short periodic orbit
visiting .Comment: Accepted for publication in Phys. Rev. E, 3 PS figure
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