arXiv subjects

Fereydoon Family

Publications and source records attributed to Fereydoon Family.

6 recordsLinked to original sources

arXiv2022

Aging in the transport on the corrugated ratchet potential

Under rapid undercooling, glass forming liquids freeze in an amorphous state that can equilibrate only on enormously long time-scales, This is the characteristic sign of aging, which has been observed in a wide range of systems. Brownian ratchet is a widely studied system that exhibits many types of anomalous dynamical behavior. We have investigated the possibility of aging in the collective motion of Brownian particles in a periodic ratchet potential with quenched disorder. We find that when a slowly growing fraction of particles are trapped for long time, the collective movement tends to become super-diffusive. The super-diffusive transport weakly breaks the ergodicity and the time to cover the whole phase space become enormously long and reminiscent of aging behavior.

cond-mat.stat-mech↗

arXiv2019

Transient Superdiffusive Motion on a Disordered Ratchet Potential

The relationship between anomalous superdiffusive behavior and particle trapping probability is analyzed on a rocking ratchet potential with spatially correlated weak disorder. The trapping probability density is shown, analytically and numerically, to have an exponential form as a function of space. The trapping processes with a low or no thermal noise are only transient, but they can last much longer than the characteristic time scale of the system and therefore might be detected experimentally. Using the result for the trapping probability we obtain an analytical expression for the number of wells where a given number of particles are trapped. We have also obtained an analytical approximation for the second-moment of the particle distribution function C2 as a function of time, when trapped particles coexist with constant velocity untrapped particles. We also use the expression for C2 to characterize the anomalous superdiffusive motion in the absence of thermal noise for the transient time.

cond-mat.stat-mech↗

arXiv2014

Chaos in Kicked Ratchets

We present a minimal one-dimensional deterministic continuous dynamical system that exhibits chaotic behavior and complex transport properties. Our model is an overdamped rocking ratchet that is periodically kicked with a delta function potential. We develop an analytical approach that predicts many key features of the system, such as current reversals, as well as the presence of chaotic behavior and bifurcation. We show that our approach can be easily extended to other types of periodic forces, including the square wave.

cond-mat.stat-mech↗

arXiv2006

Roughening, deroughening, and nonuniversal scaling of the interface width in electrophoretic deposition of polymer chains

Growth and roughness of the interface of deposited polymer chains driven by a field onto an impenetrable adsorbing surface are studied by computer simulations in (2+1) dimensions. The evolution of the interface width W shows a crossover from short-time growth described by the exponent beta1 to a long-time growth with exponent beta2 (>beta1). The saturated width increases, i.e., the interface roughens, with the molecular weight Lc, but the roughness exponent alpha (from Ws~L^alpha) becomes negative in contrast to models for particle deposition; alpha depends on the chain length--a nonuniversal scaling with the substrate length L. Roughening and deroughening occur as the field E and the temperature T compete such that Ws=(A+BT)E^-1/2.

cond-mat.soft↗

arXiv2001

Control of Current Reversal in Single and Multiparticle Inertia Ratchets

We have studied the deterministic dynamics of underdamped single and multiparticle ratchets associated with current reversal, as a function of the amplitude of the external driving force. Two experimentally inspired methods are used. In the first method the same initial condition is used for each new value of the amplitude. In the second method the last position and velocity is used as the new initial condition when the amplitude is changed. The two methods are found to be complementary for control of current reversal, because the first one elucidates the existence of different attractors and gives information about their basins of attraction, while the second method, although history dependent, shows the locking process. We show that control of current reversals in deterministic intertia ratchets is possible as a consequence of a locking process associated with different mean velocity attractors. An unlocking efect is produced when a chaos to order transition limits the control range.

cond-mat↗

arXiv2001

Quenched Disorder Effects on Deterministic Inertia Ratchets

The effect of quenched disorder on the underdamped motion of a periodically driven particle on a ratchet potential is studied. As a consequence of disorder, current reversal and chaotic diffusion may take place on regular trajectories. On the other hand, on some chaotic trajectories disorder induces regular motion. A localization effect similar to {\sl Golosov Phenomenon} sets in whenever a disorder threshold that depends on the mass of the particle is reached. Possible applications of the localization phenomenon are discussed.

cond-mat↗