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Dynamics of rotator chain with dissipative boundary

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Frontiers of physics 2014年第4期9卷 511-518页

作者： Pu Ke zhi-gang zheng Department of Physics and the Beijing Hong Kong Singapore Joint Center for Nonlinear and Complex Systems (Beijing) Beijing Normal University Beijing 100875 China

We study the deternfinistic dynanfics of rotator chain with purely mechanical driving on the boundary by stability analysis and numerical sinmlation. Globally synchronous rotation, clustered synchronous rotation, and split synchronous rotation states are identified. In particular, we find that the single-peaked wariance distribution of angular momenta is the consequence of the deterministic dynamics. As a result, the operational definition of temperature used in the previous studies on rotator chain should be revisited.

关键词： rotator chain energy conduction

Hierarchical cluster-tendency analysis of the group structure in the foreign exchange market

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Frontiers of physics 2013年第4期8卷 451-460页

作者： Xin-Ye Wu zhi-gang zheng Department of Physics and the Beijing-Hong Kong Singapore Joint Center for Nonlinear and Complex Systems Beijing Normal University Beijing 100875 China

A hierarchical cluster-tendency （HCT） method in analyzing the group structure of networks of the global foreign exchange （FX） market is proposed by combining the advantages of both the minimal spanning tree （MST） and the hierarchical tree （HT）. Fifty currencies of the top 50 World GDP in 2010 according to World Bank＇s database are chosen as the underlying system. By using the HCT method, all nodes in the FX market network can be ＂colored＂ and distinguished. We reveal that the FX networks can be divided into two groups, i.e., the Asia-Pacific group and the Pan-European group. The results given by the hierarchical cluster-tendency method agree well with the formerly observed geographical aggregation behavior in the FX market. Moreover, an oil-resource aggregation phenomenon is discovered by using our method. We find that gold could be a better numeraire for the weekly-frequency FX data.

关键词： foreign-exchange market hiergrchical cluster-tendency method hierarchical tree,minimum spanning tree

Propagation dynamics on the Fermi-Pasta-Ulam lattices

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Frontiers of physics 2013年第3期8卷 349-355页

作者： Zong-Qiang Yuan zhi-gang zheng Department of Physics and the Beijing Hong Kong-Singapore Joint Centre for Nonlinear and Complex Systems (Beijing) Beijing Normal University Beijing 100875 China

The spatiotemporal propagation of a momentum excitation on the finite Fermi-Pasta-Ulam lattices is investigated. The competition between the solitary wave and phonons gives rise to interesting propagation behaviors. For a moderate nonlinearity, the initially excited pulse may propagate co- herently along the lattice for a long time in a solitary wave manner accompanied by phonon tails. The lifetime of the long-transient propagation state exhibits a sensitivity to the nonlinear parameter. The solitary wave decays exponentially during the final loss of stability, and the decay rate varying with the nonlinear parameter exhibits two different scaling laws. This decay is found to be related to the largest Lyapunov exponent of the corresponding Hamiltonian system, which manifests a transition from weak to strong chaos. The mean-free-path of the solitary waves is estimated in the strong chaos regime, which may be helpful to understand the origin of anomalous conductivity in the Fermi-Pasta Ulam lattice.

关键词： Fermi-Past-Ulam model solitary wave low-dimensional heat conduction

Double-temperature ratchet model and current reversal of coupled Brownian motors

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Frontiers of physics 2017年第6期12卷 43-52页

作者： Chen-Pu Li Hong-Bin Chen zhi-gang zheng Department of Physics Beijing Normal University Beijing 100875 China College of Science Hebei University of ArchitectureZhangjiakou 075000 China Institute of Systems Science (ISS) Huaqiao University Xiamen 361021 China College of Information Science and Engineering Huaqiao University Xiamen 361021 China

On the basis of the transport features and experimental phenomena observed in studies of molecular motors, we propose a double-temperature ratchet model of coupled motors to reveal tile dynamical mechanism of cooperative transport of motors with two heads, where the interactions and asynchrony between two motor heads are taken into account. We investigate the collective unidirectional trans- port of coupled system and find that the direction of motion can be reversed under certain conditions. Reverse motion can be achieved by modulating the coupling strength, coupling free length, and asym- metric coefficient of the periodic potential, which is understood in terms of the effective potential theory. The dependence of the directed current on various parameters is studied systematically. Di- rected transport of coupled Brownian motors can be manipulated and optimized by adjusting the pulsation period or the phase shift of the pulsation temperature.

关键词： coupled Brownian motors ratchet model effective potential noise

Rotational effect in two-dimensional cooperative directed transport

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Frontiers of physics 2015年第1期10卷 87-94页

作者： Li-Yan Qiao Yun-yun Li zhi-gang zheng Department of Physics and the Beijing-Hong Kong-Singapore Joint Center for Nonlinear and Complex Studies Beijing Normal University Beijing 100876 China Center for Phononics and Thermal Energy Science School of Physics Science and Engineering Tongji University Shanghai 200092 China

In this review we investigate the rotation effect in the motion of coupled dimer in a two-dimensional asymmetric periodic potential. Free rotation does not generate directed transport in translational direction, while we find it plays an critical role in the motors motility when the dimer moves under the effect of asymmetry ratchet potential. In the presence of external force, we study the relation between the average current and the force numerically and theoretically. The numerical results show that only appropriate driving force could produce nonzero current and there are current transitions when the force is large enough. An analysis of stability analysis of limit cycles is applied to explain the occurrence of these transitions. Moreover, we numerically simulate the transport of this coupled dimer driven by the random fluctuations in the rotational direction. The existence of noise smooths the current transitions induced by the driving force and the resonance-like peaks which depend on the rod length emerge in small noise strength. Thanks to the noise in the rotational direction, autonomous motion emerges without the external force and large noise could make the current reversal happen. Eventually, the new mechanism to generate directed transport by the rotation is studied.

关键词： molecular motor rotational effect noise rotation-translation coupling directedtranslational motion

Ratchet motion and current motors in pulsating reversal of coupled Brownian symmetric potentials

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Frontiers of physics 2017年第4期12卷 197-206页

作者： Chen-Pu Li Hong-Bin Chen zhi-gang zheng Department of Physics Beijing Normal University Beijing 100875 China College of Science Hebei University of Architecture Zhangjiakou 075000 China Institute of Systems Science (ISS) Huaqiao University Xiamen 361021 China College of Information Science and Engineering Huaqiao University Xiamen 361021 China

In this study, we investigate the collective directed transport of coupled Brownian particles in spatially symmetric periodic potentials under time-periodic pulsating modulations. We find that the coupling between two particles can induce symmetry breaking and consequently collective directed motion. Moreover, the direction of motion can be reversed under certain conditions. The dependence of directed current on various parameters is systematically studied, reverse motion can be achieved by modulating the coupling free length and the phase shift of tile pulsating potential. The dynamical mechanism of these transport properties is understood in terms of the effective-potential theory and the space-time transformation invariance. The directed transport of coupled Brownian motors can be maniplflated and optimized by adjusting the coupling strength, pulsating frequency, or noise intensity.

关键词： coupled Brownian motors ratchet effective potential symmetric periodic potential noise

Resonant current in coupled inertial Brownian particles with delayed-feedback control

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Frontiers of physics 2017年第6期12卷 33-41页

作者： Tian-Fu Gao zhi-gang zheng Jin-Can Chen College of Physical Science and Technology Shenyang Normal University Shenyang 110034 China College of Information Science and Engineering Huaqiao University Xiamen 361021 China Department of Physics Xiamen University Xiamen 361005 China

The transport of a walker in rocking feedback-controlled ratchets is investigated. The walker consists of two coupled ＂feet＂ that allow the interchange of the order of particles while the walker moves. In the underdamped case, tile deterministic dynamics of the walker in a tilted asymmetric ratchet with an external periodic force is considered. It is found that delayed feedback ratchets with a switching-on- and-off dependence of the states of the system can lead to absolute negative mobility. In such a novel phenomenon, the particles move against tile bias. Moreover, the walker can acquire a series of resonant steps for different values of the current. It is interesting to find that the resonant currents of the walker are induced by tile phase locked motion that corresponds to the synchronization of the motion with the change in the frequency of the external driving. These resonant steps can be well predicted in terms of time-space symmetry analysis, which is in good agreement with dynamics simulations. The transport performances can be optimized and controlled by suitably adjusting the parameters of tile delayed-feedback ratchets.

关键词： delayed-feedback control absolute negative mobility resonant steps phase locking

Interface-facilitated energy transport in coupled Frenkel-Kontorova chains

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Frontiers of physics 2016年第2期11卷 125-130页

作者： Rui-Xia Su Zong-Qiang Yuan Jun Wang zhi-gang zheng Department of Physics and the Beijing-Hong Kong-Singapore Joint Centre for Nonlinear and Complex Systems (Beijing) Beijing Normal University Beijing 100875 China Science and Technology on Plasma Physics Laboratory Research Center of Laser Fusion China Academy of Engineering Physics Mianyang 621900 China Key Laboratory of Enhanced Heat Transfer and Energy Conservation (Ministry of Education) College of Environmental and Energy Engineering Beijing University of Technology Beijing 100124 China College of Information Science and Engineering Huaqiao University Xiamen 361021 China

The role of interface couplings on the energy transport of two coupled Frenkel-Kontorova （FK） chains is explored through numerical simulations. In general, it is expected that the interface cou- plings result in the suppression of heat conduction through the coupled system due to the additional interface phonon-phonon scattering. In the present paper, it is found that the thermal conductivity increases with increasing intensity of interface interactions for weak inter-chain couplings, whereas the heat conduction is suppressed by the interface interaction in the case of strong inter-chain couplings. Based on the phonon spectral energy density method, we demonstrate that the enhance- ment of energy transport results from the excited phonon modes （in addition to the intrinsic phonon modes）, while the strong interface phonon-phonon scattering results in the suppressed energy transport.

关键词： interface couplings energy transport heat conduction phonon-phonon scattering,Frenkel-Kontorova (FK) chains excited phonon modes phonon spectral energy density

Effects of frustration on explosive synchronization

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Frontiers of physics 2016年第6期11卷 67-74页

作者： Xia Huang Jian Gao Yu-Ting Sun zhi-gang zheng Can Xu Department of Mathematics and Physics North China Electric Power University Beijing 102206 China Department of Physics and the Beijing-Hong Kong-Singapore Joint Centre for Nonlinear and Complex Systems (Beijing) Beijing Normal University Beijing 100875 China College of Information Science and Engineering Huaqiao University Xiamen 361021 China

In this study, we consider the emergence of explosive synchronization in scale-free networks by considering the Kuramoto model of coupled phase oscillators. The natural frequencies of oscillators are assumed to be correlated with their degrees and frustration is included in the system. This assumption can enhance or delay the explosive transition to synchronization. Interestingly, a de-synchronization phenomenon occurs and the type of phase transition is also changed. Furthermore, we provide an analytical treatment based on a star graph, which resembles that obtained in scale-free networks. Finally, a self-consistent approach is implemented to study the de-synchronization regime. Our findings have important implications for controlling synchronization in complex networks because frustration is a controllable parameter in experiments and a discontinuous abrupt phase transition is always dangerous in engineering in the real world.

关键词： coupled phase oscillator explosive synchronization frustration