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Yuan G.-Y.,Hebei Normal University | Yuan G.-Y.,Hebei Advanced Thin Films Laboratory
Chinese Physics B | Year: 2011

We numerically study the dynamics of spiral waves in the excitable system with the excitability modulated by a rectangle wave. The tip trajectories and their variations with the modulation period T are explained by the corresponding spectrum analysis. For a large T, the external modulation leads to the occurrence of more frequency peaks and these frequencies change with the modulation period according to their specific rules, respectively. Some of the frequencies and a primary frequency f1 determine the corresponding curvature periods, which are locked into rational multiplies of the modulation period. These frequency-locking behaviours and the limited life-span of the frequencies in their variations with the modulation period constitute many resonant entrainment bands in the T axis. In the main bands, which follow the relation T/T12 = m/n, the size variable Rx of the tip trajectory is a monotonic increasing function of T. The rest of the frequencies are linear combinations of the two ones. Due to the complex dynamics, many unique tip trajectories appear at some certain T. We find also that spiral waves are eliminated when T is chosen from the end of the main resonant bands. This offers a useful method of controling the spiral wave. © 2011 Chinese Physical Society and IOP Publishing Ltd.


Yuan G.-Y.,Hebei Normal University | Yuan G.-Y.,Hebei Advanced Thin Films Laboratory
Communications in Theoretical Physics | Year: 2011

We numerically study the dynamics of meandering spiral waves in the excitable system subjected to a feedback signal coming from two measuring points located on a straight line together with the initial spiral core. The core location and size radius of the final attractors are computed, and they change with the position of the moving measuring point in a unique way. By the Fourier Spectral analysis, we find the frequency-locked behaviors different from the driving scheme of the external periodic force. It is also found that the meandering spiral wave can be eliminated when the moving measuring point approaches closely the boundary and its feedback gain is large enough. This offers an effective and convenient method for eliminating meandering spiral waves. © 2011 Chinese Physical Society and IOP Publishing Ltd.


Yuan G.,Hebei Normal University | Yuan G.,Hebei Advanced Thin Films Laboratory | Liu Y.,Hebei Normal University | Xu A.,CAS Beijing Institute of Applied Physics And Computational Mathematics | Wang G.,CAS Beijing Institute of Applied Physics And Computational Mathematics
Nonlinear Dynamics | Year: 2012

We study the effects of a dichotomous periodic force on meandering and rigidly rotating spiral waves. For a meandering state, the periodic forcing induces more modulating frequencies according to the rules of frequency-locked relations and linear combinations. It can also generate some unique closed tip orbits. On the modulating period T-axis, there exist all kinds of resonant entrainment bands. Arnold tongues exist in the period-amplitude space. The width of entrainment bands is affected by the symmetry of positive and negative parts in each signal unit. In addition, appropriate choices of T-value can be used to eliminate spiral waves. For a rigidly rotating state, the periodic forcing can induce a transition toward meandering spiral waves via generating a transitive bidirectional spiral wave. It is very interesting that, after the transition, the meandering spiral wave has the same primary rotating period as the free meandering states. © Springer Science+Business Media B.V. 2012.


Song L.-H.,Hebei Normal University | Song L.-H.,Hebei Advanced Thin Films Laboratory | Song L.-H.,Hebei Polytechnic University | Duan C.-G.,Hebei Normal University | Duan C.-G.,Hebei Advanced Thin Films Laboratory
Physical Review C - Nuclear Physics | Year: 2010

Semi-inclusive deep inelastic scattering on nuclear targets is an ideal tool to study the energy loss effect of an outgoing quark in a nuclear medium. By means of the short hadron formation time, the experimental data with quark hadronization occurring outside the nucleus are picked out. A leading-order analysis is performed for the hadron multiplicity ratios as a function of the energy fraction on helium, neon, and copper nuclei relative to deuteron for the various identified hadrons. It is shown that the nuclear effects on parton distribution functions can be neglected. It is found that the theoretical results considering the nuclear modification of fragmentation functions due to quark energy loss are in good agreement with the experimental data. Whether the quark energy loss is linear or quadratic with the path length is not determined. The obtained energy loss per unit length is 0.38±0.03 GeV/fm for an outgoing quark by the global fit. © 2010 The American Physical Society.


An X.-T.,Hebei University of Science and Technology | An X.-T.,Hebei Normal University | Liu J.-J.,Hebei Normal University | Liu J.-J.,Hebei Advanced Thin Films Laboratory
Applied Physics Letters | Year: 2010

We study the spin polarization and the spin accumulation in an Aharonov-Bohm ring structure, in which a quantum dot (QD) array is side-coupled to one arm of the ring and the Rashba spin-orbit interaction exists in the other. The device can be as a spin switch by decreasing the tunneling coupling between the QD array and the ring. Moreover, we find that the spin polarization and the spin accumulation in the QD are affected by the number of the QDs in the QD array and can be controlled by the strength of the Rashba spin-orbit interaction and the bias on the Aharonov-Bohm ring. © 2010 American Institute of Physics.

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