Investigation On The Transport Efficiency Of Overdamped Feedback-coupled Ratchet

The investigation of directied transport of biological molecular motor has attracted the attention of scholars.Molecular motors are enzyme protein macromolecules.They are widely distributed in the body,and transport all kinds of organisms and other substances in the organelles.The molecular motor can directly convert chemical energy into mechanical energy in the actual directed transport process,and the energy conversion efficiency far beyond the current artificial motor,so the research of molecular motor directional transport and efficiency is necessary.The molecular motor scale is very small,usually in the order of nanometer,it has obvious Brownian motion characteristics.In addition,the molecular motor occurs random fluctuations and a series of sustained and periodic chemical reaction in the catalytic hydrolysis,that result in the motor itself will appear a series of conformational changes,those conformation changes of the motor head lead to the action changes between head and the,so the motor occurs directed movement in the free distribution.In the process of directed movement along the orbit of molecular motor,and the effect of track is different in different locations,so the head position of the motor can influence the force between motor and orbit.According to the mechanism of action,this paper discusses the feedback control in directed transport of Brown ratchet,and adopts the closed-loop control mechanism.The advantage of this control strategy is that it depends on the state or information of the system.The problems such as the average velocity of the center of mass and the energy conversion efficiency when the particles are subjected to square wave force and harmonic force in the feedback coupled brown ratchet are discussed in this paper.It is found that the average velocity of the center of mass can appear the peak value with the increase of the external force when the coupling particles are subjected to square wave force.However,with the increase of the external force period,the average velocity of the center of mass under different potential asymmetries is quasi-periodic change.In addition,as the external force amplitude increases,the energy efficiency of the feedback ratchet can be maximized.It is also found that when the coupling particles are subjected to the harmonic force,the average velocity of the coupled particles can show a peak as the external force changes.With the increase of the external force frequency,the average velocity and energy conversion efficiency of the coupled particles can reach the maximum.At the same time,with the increase of phase,the average velocity and energy conversion efficiency of the coupled particles appear periodical change,and there is an optimized phase in each change period to maximize the directional transport of the coupling particles.The conclusion of this paper can also play a theoretical role in the directional transport of nano-scale molecular motor and the improvement of energy conversion efficiency of the power system.