Deterministic stochastic resonance in a Rössler oscillator

Diversity-induced coherence resonance in spatially extended chaotic systems

The effect of parameter diversity on coupled Chua systems is investigated. In the absence of diversity, the systems jump back and forth between two variable domains of a chaotic attractor, and the residence times within a single domain are uncertain. By introducing parameter diversity, a combined numerical and analytical approach indicates that the systems can jump regularly from one domain to another at an intermediate range of diversity, a signature of coherence resonance. Furthermore, the influences of coupling strength and the number of units are also considered. Our results provide a possibility for the control of chaos in spatially extended chaotic systems by the manipulation of parameter diversity.

Multipeaked probability distributions of recurrence times

We determine probabilities of recurrence time into finite-sized, physically meaningful subsets of phase space. We consider three different autonomous chaotic systems: (i) scattering in a three-peaked potential, (ii) connected billiards, and (iii) Lorenz equations. We find multipeaked probability distributions, similar to the distributions found in (driven) stochastically resonant systems. In nondriven systems, such as ours, only monotonic decaying distributions (exponentials, stretched exponentials, power laws, and slight variations or combinations of these) have hitherto been reported. Discrete peaks in autonomous systems have as yet escaped attention in autonomous systems and correspond to specific trajectory subsets involving an integer number of loops.

Subharmonic transitions in a bistable oscillator with bimodal periodic excitation

We analyze the phenomenon of low-frequency signal enhancement in a bistable system excited by a sum of low-frequency and high-frequency harmonic signals. A mechanism alternate to chaotic resonance is discussed. It is shown that a high-frequency signal may generate interwell transitions of subharmonic frequency. If the frequency of the slow signal is equal or close to a subharmonic frequency of the fast signal, then the improvement of the low-frequency constituent in the output spectrum is due to sustained subharmonic resonance.