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Feedback control of two-headed Brownian motors in flashing ratchet potential

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Chinese Physics B 2010年第11期19卷 174-178页

作者：赵阿可张红卫李玉晓 College of Physics and Electric Information Luoyang Normal University Luoyang 471022 China School of Physics and Engineering Zhengzhou University Zhengzhou 450052 China Department of Physics Zhengzhou Normal University Zhengzhou 450044 China

We presented a detailed investigation on the movement of two-headed Brownian motors in an asymmetric potential under a feedback control. By numerical simulations the direct current is obtained. The current is periodic in the initial length of spring. There is an optimal value of the spring constant. And the dependence of the current on the opposing force is reversed. Then we found that when the change of the temperature and the opposing force have optimal values, the Brownian motors can also obtain the optimal efficiency.

关键词： Brownian motors ratchet current efficiency

The westward drift of the lithosphere:A tidal ratchet?

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Geoscience Frontiers 2018年第2期9卷 403-414页

作者： A.Carcaterra C.Doglioni Dipartimento di Ingegneria Meccanica e Aerospaziale Sapienza UniversityRomeItaly Istituto Nazionale di Geofisica e Vulcanologia RomeItaly Dipartimento di Scienze della Terra Sapienza UniversityRomeItaly

Is the westerly rotation of the lithosphere an ephemeral accidental recent phenomenon or is it a stable process of Earth's geodynamics? The reason why the tidal drag has been questioned as the mechanism determining the lithospheric shift relative to the underlying mantle is the apparent too high viscosity of the asthenosphere. However, plate boundaries asymmetries are a robust indication of the 'westerly'decoupling of the entire Earth's outer lithospheric shell and new studies support lower viscosities in the low-velocity layer(LVZ) atop the asthenosphere. Since the solid Earth tide oscillation is longer in one side relative to the other due to the contemporaneous Moon's revolution, we demonstrate that a non-linear rheological behavior is expected in the lithosphere mantle interplay. This may provide a sort of ratchet favoring lowering of the LVZ viscosity under shear, allowing decoupling in the LVZ and triggering the westerly motion of the lithosphere relative to the mantle.

关键词： Westward drift of the lithosphere Tectonic equator Low-velocity layer Asthenosphere viscosity Non-linear rheology Tidal ratchet

Flux of a ratchet Model and Applications to Processive Motor Proteins

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Communications in Theoretical Physics 2015年第10期64卷 415-419页

作者：李静辉 Faculty of Science Ningbo University

In this paper, we investigate the stationary probability current(or flux) of a Brownian ratchet model as a function of the flipping rate of the fluctuating potential barrier. It is shown that, with suitably selecting the parameters' values of the ratchet system, we can get the negative resonant activation, the positive resonant activation,the double resonant activation, and the current reversal, for the stationary probability current versus the flipping *** appearance of these phenomena is the result of the cooperative effects of the potential's dichotomous fluctuations and the internal thermal fluctuations on the evolution of the flux versus the flipping rate of the fluctuating potential barrier. In addition, some applications of our results to the motor proteins are discussed.

关键词： ratchet fluctuating potential resonant activation

Coefficient of Performance at Maximum χ-Criterion for Feynman ratchet as a Refrigerator

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Communications in Theoretical Physics 2014年第10期61卷 589-595页

作者：盛世奇杨盼涂展春 Department of Physics Beijing Normal University Kavli Institute for Theoretical Physics China the Chinese Academy of Sciences

The χ-criterion is defined as the product of the energy conversion efficiency and the heat absorbed per unit time by the working substance [de Tom′as et al., Phys. Rev. E 85(2012) 010104(R)]. The χ-criterion for Feynman ratchet as a refrigerator operating between two heat baths is optimized. Asymptotic solutions of the coefficient of performance at maximum χ-criterion for Feynman ratchet are investigated at both large and small temperature difference. An interpolation formula, which fits the numerical solution very well, is proposed. Besides, the sufficient condition for the universality of the coefficient of performance at maximum χ is investigated.

关键词： Feynman ratchet refrigerator coefficient of performance χ-criterion universal COP

On the Feynman ratchet and the Brownian Motor

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Open Journal of Biophysics 2018年第1期8卷 22-30页

作者： Gyula Vincze Gyula Peter Szigeti Andras Szasz Department of Biotechnics St. Istvan University Budapest Hungary Institute of Human Physiology and Clinical Experimental Research Semmelweis University Budapest Hungary

We study the Brownian ratchet conditions starting with Feynman’s proposal. We show that this proposal is incomplete, and is in fact non-workable. We give the correct model for this ratchet.

关键词： Brownian Motor Feynman ratchet Self-Sustaining Oscillation

DNA Nano Devices as a Biased Random Walk Process: A Case Study of Isothermal ratchet?

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Materials Sciences and Applications 2015年第5期6卷 401-419页

作者： Jean-Pierre Aimé Juan Elezgaray CBMN CNRS-University of Bordeaux Pessac France

Computation and amplification processes based on Networks of Chemical Reactions are at the heart of our understanding of the regulation and error correction of life systems. The recent advances in DNA nanotechnology, with the creation of the modular structures origamis and the development of dynamical networks using the toe hold mediated strand displacement, open fertile areas to construct Hierarchical Cascades of Chemical Reactions with an increasing complexity inspired from systems in biology. DNA strands have the great advantage to design autonomous and homogeneous Networks of Chemical Reactions leaving aside companion chemical reactions as it occurs in biological systems. In the present paper, we use the Fokker Planck equation to extract predictions that address a wider class of systems beyond the case of diluted solutions. We introduce the concept of toehold strength and output strength that leads to an exponential square dependence of the toehold strength divided by the output strength on the escape rate and the probability for the output strand to leave the gate. We highlight the influence of the boundary conditions that may have an important consequence in confined environment when modular structures like origamis are employed.

关键词： DNA Nanotechnology Isothermal ratchet Confined Chemical Reactions DNA Logical Gate DNA Origami Modular Algorithm

Electronic ratchet Nanodiodes

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Engineering（科研） 2009年第2期1卷 127-131页

作者： Kunyuan XU Gang WANG 不详

Using a two-dimensional ensemble Monte Carlo (EMC) method, electronic nanometer devices with different parameters are studied in detail. Calculation results show that at nanoscale the electric properties of interface inside the devices play an important role in determining the working properties of the devices. By properly arranging device structures, surface charges originated from device fabrication can be exploited to produce a predetermined electric potential in the devices. Based on this fact, two structures that can lead to an asymmetric potential along their nanochannel are proposed for designing strong nonlinear devices. Further studies indicate that ratchet effect brought by the asymmetric potential results in diode-like current-voltage characteristics of the devices. Through optimizing device parameters, zero threshold voltage can be achieved, which is desired for detecting applications. Moreover, since the devices are at nanoscale, simulation results reveal that used as rectifiers the working frequencies can be up to a few THz.

关键词： ratchet Effect Nanodiode Asymmetric Monte Carlo

Brownian ratchets driven by flashing noise strength

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Chinese Science Bulletin 1999年第21期44卷 1956-1961页

作者： ZHAO Tongjun, ZHAN Yong, ZHUO Yizhong and WU XizhenDepartment of Applied Mathematics and Physics , Hebei University of Technology , Tianjin 300130, China China Institute of Atomic Energy, Beijing 102413, China Institute of Theoretical Physics, Chinese Academy of Sciences , Beijing 100080, China Corresponding author Dept. of Appl. Math. and Physics Hebei University of Technology Tianjin 300130 China China Institute of Atomic Energy Beijing 102413 China Institute of Theoretical Physics Chinese Academy of Sciences Beijing 100080 China

The stochastic transport driven by flashing multi-noise sources in a ratchet is studied. The stationary current versus the noise strength and the colored noise correlated time T is obtained . At a fixed flip rate and strength of the colored noises, the novel phenomenon of the current reversal occurs as T reaches a certain value. More than one reversal point exists when

关键词： flashing force ratchet current reversal Langevian equation.

Coulomb Friction Driving Brownian Motors

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Communications in Theoretical Physics 2014年第10期61卷 505-513页

作者： Alessandro Manacorda Andrea Puglisi Alessandro Sarracino Dipartimento di Fisica Università "Sapienza"p.le A.Moro 200185 RomeItaly Istituto dei Sistemi Complessi - CNR and Dipartimento di Fisica Università "Sapienza"p.le A.Moro 200185 RomeItaly Kavli Institute for Theoretical Physics China the Chinese Academy of Sciences Laboratoire de Physique Théorique de la Matière Condensée CNRS UMR 7600case courrier 121Université Paris 64Place Jussieu75255 Paris CedexFrance

We review a family of models recently introduced to describe Brownian motors under the influence of Coulomb friction, or more general non-linear friction laws. It is known that, if the heat bath is modeled as the usual Langevin equation(linear viscosity plus white noise), additional non-linear friction forces are not sufficient to break detailed balance, i.e. cannot produce a motor effect. We discuss two possibile mechanisms to elude this problem. A first possibility, exploited in several models inspired to recent experiments, is to replace the heat bath's white noise by a "collisional noise", that is the effect of random collisions with an external equilibrium gas of particles. A second possibility is enlarging the phase space, e.g. by adding an external potential which couples velocity to position, as in a Klein–Kramers equation. In both cases, non-linear friction becomes sufficient to achieve a non-equilibrium steady state and, in the presence of an even small spatial asymmetry, a motor effect is produced.

关键词： Brownian motors ratchet effect Coulomb friction