arXiv subjects

H. S. Wio

Publications and source records attributed to H. S. Wio.

24 records · Page 2Linked to original sources

arXiv2001

Experimental evidence of stochastic resonance without tuning due to non Gaussian noises

In order to test theoretical predictions, we have studied the phenomenon of stochastic resonance in an electronic experimental system driven by white non Gaussian noise. In agreement with the theoretical predictions our main findings are: an enhancement of the sensibility of the system together with a remarkable widening of the response (robustness). This implies that even a single resonant unit can reach a marked reduction in the need of noise tuning.

cond-mat.stat-mech↗

arXiv2000

Transition from anomalous to normal hysteresis in a system of coupled Brownian motors: a mean field approach

We address a recently introduced model describing a system of periodically coupled nonlinear phase oscillators submitted to multiplicative white noises, wherein a ratchet-like transport mechanism arises through a symmetry-breaking noise-induced nonequilibrium phase transition. Numerical simulations of this system reveal amazing novel features such as negative zero-bias conductance and anomalous hysteresis, explained resorting to a strong-coupling analysis in the thermodynamic limit. Using an explicit mean-field approximation we explore the whole ordered phase finding a transition from anomalous to normal hysteresis inside this phase, estimating its locus and identifying (within this scheme) a mechanism whereby it takes place.

cond-mat.stat-mech↗

arXiv2000

On the Influence of Noise on the Critical and Oscillatory Behavior of a Predator-Prey Model: Coherent Stochastic Resonance at the Proper Frequency

Noise induced changes in the critical and oscillatory behavior of a Prey-Predator system are studied using power spectrum density and Spectral Amplification Factor (SAF) analysis. In the absence of external noise, the population densities exhibit three kinds of asymptotic behavior, namely: Absorbing State, Fixed Point (FP) and an Oscillatory Regime (OR) with a well defined proper (natural) frequency. The addition of noise destabilizes the FP phase inducing a transition to a new OR. Surprisingly, it is found that when a periodic signal is added to the control parameter, the system responds robustly, without relevant changes in its behavior. Nevertheless, the "Coherent Stochastic Resonance" phenomenon is found only at the proper frequency. Also, a method based on SAF allows us to locate very accurately the transition points between the different regimes.

cond-mat.stat-mech↗

arXiv1999

Exact expression for the diffusion propagator in a family of time-dependent anharmonic potentials

We have obtained the exact expression of the diffusion propagator in the time-dependent anharmonic potential $V(x,t)={1/2}a(t)x^2+b\ln x$. The underlying Euclidean metric of the problem allows us to obtain analytical solutions for a whole family of the elastic parameter a(t), exploiting the relation between the path integral representation of the short time propagator and the modified Bessel functions. We have also analyzed the conditions for the appearance of a non-zero flow of particles through the infinite barrier located at the origin (b<0).

cond-mat.stat-mech↗

arXiv1999

Enhancement of Stochastic Resonance in distributed systems due to a selective coupling

Recent massive numerical simulations have shown that the response of a "stochastic resonator" is enhanced as a consequence of spatial coupling. Similar results have been analytically obtained in a reaction-diffusion model, using "nonequilibrium potential" techniques. We now consider a field-dependent diffusivity and show that the "selectivity" of the coupling is more efficient for achieving stochastic-resonance enhancement than its overall value in the constant-diffusivity case.

cond-mat.stat-mech↗

arXiv1997

Disordering effects of color in nonequilibrium phase transitions induced by multiplicative noise

The model introduced by Van den Broeck, Parrondo and Toral [Phys. Rev. Lett.73, 3395 (1994)] -- leading to a second-order-like noise-induced nonequilibrium phase transition which shows reentrance as a function of the (multiplicative) noise intensity $σ$-- is investigated beyond the white-noise assumption. Through a Markovian approximation and within a mean-field treatment it is found that -- in striking contrast with the usual behavior for equilibrium phase transitions -- for noise self-correlation time $τ>0$, the stable phase for (diffusive) spatial coupling $D\to\infty$ is always the disordered one. Another surprising result is that a large noise "memory" also tends to destroy order. These results are supported by numerical simulations.

cond-mat↗