53 research outputs found
Deterministic inhomogeneous inertia ratchets
We study the deterministic dynamics of a periodically driven particle in the
underdamped case in a spatially symmetric periodic potential. The system is
subjected to a space-dependent friction coefficient, which is similarly
periodic as the potential but with a phase difference. We observe that
frictional inhomogeneity in a symmetric periodic potential mimics most of the
qualitative features of deterministic dynamics in a homogeneous system with an
asymmetric periodic potential. We point out the need of averaging over the
initial phase of the external drive at small frictional inhomogeneity parameter
values or analogously low potential asymmetry regimes in obtaining ratchet
current. We also show that at low amplitudes of the drive, where ratchet
current is not possible in the deterministic case, noise plays a significant
role in realizing ratchet current.Comment: 15 pages, 15 figure
Two-Well System under Large Amplitude Periodic Forcing: Stochastic Synchronization, Stochastic Resonance and Stability
We study the residence time distributions and explore the possibility of
observing stochastic resonance and synchonization of passages in a two-well
system driven by a periodic forcing of amplitude larger than a marginal value
beyond which one of the two wells become unstable and diasppear. We define and
calculate hysteresis loop in the system, the area of which measures the degree
of synchronization between the residence time statistics and the input signal,
as a function of input noise strength. We analyse the noise induced stability
obtained in such a deterministically overall unstable system and within this
context discuss the above two phenomena.Comment: Mod. Phys. Lett. B 1997, in print, figures available on reques
AC driven thermal ratchets
We consider the motion of a overdamped Brownian particle in periodic
asymmetric potential with space dependent friction coefficient. In the presence
of external time periodic forcing, the system shows multiple current reversals
on varying the amplitude of the external forcing and the temperature of the
thermal bath. In the adiabatic regime we find a single reversal of current as a
function of noise strength which can only be accounted due to the presence of
space dependent friction coefficient. For very large forcing term, the current
does not go to zero, instead it asymptotically tends to a limiting value
depending on the phase shift between the potential and the friction. This fact
plays an important role in obtaining multiple current reversals.Comment: 4 pages, latex/revtex, 4 eps figures. Proceedings of CMDAYS2K, held
at Guru Ghasidas University, Bilaspur, Chattisgarh, India, Aug 29-31, 2
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