arXiv subjects

Bao-quan Ai

Publications and source records attributed to Bao-quan Ai.

43 records · Page 3Linked to original sources

arXiv2010

Transport Reversal in a Thermal Ratchet

Transport of a Brownian particle moving in a periodic potential is investigated in the presence of symmetric unbiased external force. The viscous medium is alternately in contact with the two heat reservoirs. We present the analytical expression of the net current at quasi-steady state limit. It is found that the competition of the asymmetric parameter of potential with the temperature difference leads to the phenomena like current reversal. The competition between the two driving factors is a necessary but not a sufficient condition for current reversals.

physics.bio-ph↗

arXiv2010

Transport of overdamped Brownian particles in a two-dimensional tube: Nonadiabatic regime

Transport of overdamped Brownian particles in a two-dimensional asymmetric tube is investigated in the presence of nonadiabatic periodic driving forces. By using Brownian dynamics simulations we can find that the phenomena in nonadiabatic regime differ from that in adiabatic case. The direction of the current can be reversed by tuning the driving frequency. Remarkably, the current as a function of the driving amplitude exhibits several local maxima at finite driving frequency.

cond-mat.soft↗

arXiv2007

Facilitated movement of inertial Brownian motors driven by a load under an asymmetric potential

Based on recent work [L. Machura, M. Kostur, P. Talkner, J. Luczka, and P. Hanggi, Phys. Rev. Lett. 98, 040601 (2007)], we extend the study of inertial Brownian motors to the case of an asymmetric potential. It is found that some transport phenomena appear in the presence of an asymmetric potential. Within tailored parameter regimes, there exists two optimal values of the load at which the mean velocity takes its maximum, which means that a load can facilitate the transport in the two parameter regimes. In addition, the phenomenon of multiple current reversals can be observed when the load is increased.

cond-mat.stat-mech↗

arXiv2007

Thermal noise can facilitate energy transformation in the presence of entropic barriers

Efficiency of a Brownian particle moving along the axis of a three-dimensional asymmetric periodic channel is investigated in the presence of a symmetric unbiased force and a load. Reduction of the spatial dimensionality from two or three physical dimensions to an effective one-dimensional system entails the appearance of entropic barriers and an effective diffusion coefficient. The energetics in the presence of entropic barriers exhibits peculiar behavior which is different from that occurring through energy barriers. We found that even on the quasistatic limit there is a regime where the efficiency can be a peaked function of temperature, which indicates that thermal noise can facilitate energy transformation, contrary to the case of energy barriers. The appearance of entropic barriers may induce optimized efficiency at a finite temperature.

cond-mat.stat-mech↗

arXiv2007

Current in a three-dimensional periodic tube with unbiased forces

Transport of a Brownian particle moving along the axis of a three-dimensional asymmetric periodic tube is investigated in the presence of asymmetric unbiased forces. The reduction of the coordinates may involve not only the appearance of entropic barrier but also the effective diffusion coefficient. It is found that in the presence of entropic barrier, the asymmetry of the tube shape and the asymmetry of the unbiased forces are the two ways of inducing a net current. The current is a peaked function of temperature which indicates that the thermal noise may facilitate the transport even in the presence of entropic barrier. There exists an optimized radius at the bottleneck at which the current takes its maximum value. Competition between the two opposite driving factors may induce current reversal.

cond-mat.stat-mech↗

arXiv2003

Structures of Rotating Traditional Neutron Stars and Hyperon Stars in the Relativistic $σ-ω$ Model

The influence of the rotation on the total masses and radii of the neutron stars are calculated by the Hartle's slow rotation formalism, while the equation of state is considered in a relativistic $σ-ω$ model. Comparing with the observation, the calculating result shows that the double neutron star binaries are more like hyperon stars and the neutron stars of X-ray binaries are more like traditional neutron stars. As the changes of the mass and radius to a real neutron star caused by the rotation are very small comparing with the total mass and radius, one can see that Hartle's approximate method is rational to deal with the rotating neutron stars. If three property values: mass, radius and period are observed to the same neutron star, then the EOS of this neutron star could be decided entirely.

astro-ph↗

arXiv2003

Sliding Mechanism for Actin Myosin System

Based on the Stochastic Inclined Rods Model (SIRM) proposed by H. Matsuura and M. Nakano, we study the microscopic motion of actin myosin system including the motion of the G-actin. Our model is composed of an inclined spring (rod), a myosin head, a myosin filament and G-actins. We discuss the stochastic resonance between the myosin head and random noise. The results of calculation show that the model can convert the random motion to one directional motion, and the myosin head works as a resonator of random noise which absorbs the energy through the stochastic resonance. The intermolecular potential between the myosin head and G-actin and the inclined rod play a key role for the muscle's motion. The energy consumed by the motor is directly supplied from the surroundings (i.e., the thermal motions of water molecules).

physics.bio-ph↗