Chun-Ni Wang

Lanzhou University of Technology, Kao-lan-hsien, Gansu Sheng, China

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Publications (14)15.99 Total impact

  • Chun-Ni Wang, Jun Ma, Wu-Yin Jin
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    ABSTRACT: The synchronization and parameter identification of six unknown parameters in a chaotic neuron model, which one parameter (about 0.006) is 3 orders of magnitude smaller than the others (about 1–5), is investigated by using Lyapunov stability theory and adaptive synchronization in detail. Two gain coefficients (δ1, δ2) are introduced into the Lyapunov function to obtain certain optimized controllers and parameter observers. A selectable amplification factor k 0 is presented using scale conversion and it is used to improve the accuracy of parameter estimation with the smallest order. The parameter space for gain coefficient (δ) versus amplification factor k 0, and the parameter space δ1 versus δ2 at certain fixed amplification factor k 0 are calculated numerically. It is found that the selection values of optimized gain coefficients and amplification factor are critical to estimate the six unknown parameters, particularly for the smallest unknown parameters with an order 0.001. The extensive numerical results show that it is more effective to estimate the smallest unknown parameter r when the two gain coefficients δ1 and δ2 are given the same value and a higher amplification factor k 0 is used. It could be useful to estimate the unknown parameters with large deviation of order magnitude, such as a single chaotic Josephson junction coupled to a Resonant tank and other chaotic systems with potential application [Z.Y. Wang, H.Y. Liao, and S.P. Zhou, Study of the DC biased Josephson junction coupled to a Resonant tank, Acta. Phys. Sin. 50(10) (2001), pp. 1996–2000 (in Chinese)].
    Dynamical Systems 01/2012; 27(2). · 0.72 Impact Factor
  • Chun-Ni Wang, Jun Ma, Yong Liu, Long Huang
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    ABSTRACT: In this paper, a certain kind of intermittent scheme is used to control the chaos in a single chaotic Chua circuit to reach an arbitrary orbit. Furthermore, it is confirmed to be effective in suppressing spatiotemporal chaos and a spiral wave in the networks of Chua circuits with nearest-neighbor connections. The controllable and measurable variable is sampled, and the linear error between the sampled variable and the selected thresholds is fed back into the system only if the sampled variable exceeds the thresholds; otherwise, the system will develop itself without any external perturbation. In experiments, the control scheme could be realized by using the Heavside function. In the case of one single chaotic Chua circuit, the chaotic state can be controlled to reach an arbitrary n-periodical orbit (n=1,2,3,5,6,…) with appropriate feedback intensity and thresholds. It is argued that this scheme could explain the mechanism of what is called phase compression. Then the phase compression scheme is used to control a spiral wave and spatiotemporal chaos in a network of Chua circuits with 256×256 sites. The numerical simulation results confirm its effectiveness when appropriate upper and bottom thresholds are used by monitoring the measurable output voltages of the chaotic circuit in one site of the network.
    Nonlinear Dynamics 01/2012; 67(1). · 3.01 Impact Factor
  • Jun Ma, Ya Jia, Chun-Ni Wang, Wu-Yin Jin
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    ABSTRACT: In this paper, the condition of completely nearest-neighbor couplings is introduced into the coupled Hindmarsh-Rose neurons in two-dimensional arrays. It is found that the stable rotating spiral wave can be developed and the transition of spiral wave in the coupled Hindmarsh-Rose neurons are investigated. The factor of synchronization is defined to investigate the development and instability of the spiral wave. Furthermore, the external injected current, coupling coefficients and other decisive bifurcation parameter r and χ, are endowed with different values to study the transition of spiral wave by analyzing the factor of synchronization and the snapshots of the activator. It is found that the critical sudden change points in the curve for factor of synchronization often indicates sudden transition of spiral wave, the instability or death of the spiral wave. The snapshots are also plotted to confirm the results from the curve of the factor of synchronization. Finally, the noise-induced instability and chaotic logistic map-induced instability of spiral wave are investigated and discussed.
    International Journal of Modern Physics B 01/2011; 25(12):1653-1670. · 0.46 Impact Factor
  • Chun-Ni Wang, Jun Ma, Wuyin Jin, Ying Wu
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    ABSTRACT: An additional gradient force is often used to simulate the polarization effect induced by the external field in the reaction–diffusion systems. The polarization effect of weak electric field on the regular networks of Hodgkin–Huxley neurons is measured by imposing an additive term VE on physiological membrane potential at the cellular level, and the dynamical evolution of spiral wave subjected to the external electric field is investigated. A statistical variable is defined to study the dynamical evolution of spiral wave due to polarization effect. In the numerical simulation, 40000 neurons placed in the 200×200 square array with nearest neighbor connection type. It is found that spiral wave encounters death and the networks become homogeneous when the intensity of electric field exceeds the critical value, otherwise, spiral wave keeps alive completely. On the other hand, breakup of spiral wave occurs as the intensity of electric field exceeds the critical value in the presence of weak channel noise, otherwise, spiral wave keeps robustness to the external field completely. The critical value can be detected from the abrupt changes in the curve for factors of synchronization vs. control parameter, a smaller factor of synchronization is detected when the spiral wave keeps alive.
    Applied Mathematics and Computation. 01/2011; 218:4467-4474.
  • Jun Ma, Jun Tang, Chun-Ni Wang, Ya Jia
    International Journal of Bifurcation and Chaos 01/2011; 21(02):587-. · 0.92 Impact Factor
  • Jun Ma, Chun-Ni Wang, Jun Tang, Ya Jia
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    ABSTRACT: In this paper, a new scheme is proposed to remove the spiral wave in a two-dimensional Fithhugh–Nagumo type equation by introducing a class of vortex electric field into the media. A long electric solenoid with large pipe diameter is used to generate a spatial magnetic field and the intensity of magnetic field B is controllable. A vortex electric field could be induced by changing the external magnetic field B. The media is polarized and the membrane potential is changed as the vortex electric field is imposed on the media. The polarization effect of the external field on the media is discussed. It argued that the effect of the external electric field could be reproduced with a spatial stimulation current (transformed membrane current)imposed on the media, which is approached by Iex∝r2dB/dt and is the coordinate origin, (x,y) defines the site position. The spatial polarized field introduces vortex electric current Iex∝r2dB/dt into the media and it differs from the external forcing by placing electrode into the media. The external current is transformed into membrane current Ist∝r4(dB/dt)2 to change the potential of the membrane. The numerical results confirm that the spiral wave could be removed with appropriate vortex electric field or current. The final state will be stable when the transformed membrane current or the extern polarized field is a constant signal, and the whole system will oscillate periodically when the external polarized field or transformed membrane current is changed with a periodical signal. Furthermore, the spiral wave still be removed even if the spatiotemporal noise is introduced into all the media.
    Communications in Nonlinear Science and Numerical Simulation 01/2010; · 2.77 Impact Factor
  • Chun-Ni Wang, Li-Jian Yang, Li-Hua Yuan, Jun Ma
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    ABSTRACT: The effect of asymmetrical diffusion in elastic media on the spiral wave is investigated by using different changeable diffusion coefficients ( along the orthometric coordinate axes x and y). The space of adjacent sites changes when deformation of media is considered, and thus the diffusion coefficients are changeable. A stochastic phase is introduced into the changeable diffusion coefficients to simulate the case for asymmetrical diffusion and the results are compared with the ones for symmetrical diffusion. It is found that spiral wave can keep its robustness when the frequency of changeable diffusion coefficients is increasing beyond certain threshold (usually about the intrinsic frequency), spiral wave can become deformed when the frequency of diffusion coefficients is decreased. Otherwise, the spiral wave will be removed when the diffusion coefficients change with certain frequency close to the intrinsic frequency.
    Communications in Nonlinear Science and Numerical Simulation 01/2010; · 2.77 Impact Factor
  • Chun-Ni Wang, Jun Ma, Jun Tang, Yan-Long Li
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    ABSTRACT: Spiral wave could be observed in the excitable media, the neurons are often excitable within appropriate parameters. The appearance and formation of spiral wave in the cardiac tissue is linked to monomorphic ventricular tachycardia that can denervate into polymorphic tachycardia and ventricular fibrillation. The neuronal system often consists of a large number of neurons with complex connections. In this paper, we theoretically study the transition from spiral wave to spiral turbulence and homogeneous state (death of spiral wave) in two-dimensional array of the Hindmarsh-Rose neuron with completely nearest-neighbor connections. In our numerical studies, a stable rotating spiral wave is developed and selected as the initial state, then the bifurcation parameters are changed to different values to observe the transition from spiral wave to homogeneous state, breakup of spiral wave and weak change of spiral wave, respectively. A statistical factor of synchronization is defined with the mean field theory to analyze the transition from spiral wave to other spatial states, and the snapshots of the membrane potentials of all neurons and time series of mean membrane potentials of all neurons are also plotted to discuss the change of spiral wave. It is found that the sharp changing points in the curve for factor of synchronization vs. bifurcation parameter indicate sudden transition from spiral wave to other states. And the results are independent of the number of neurons we used.
    Communications in Theoretical Physics - COMMUN THEOR PHYS. 01/2010; 53(2):382-388.
  • Chun-Ni Wang, Shi-Rong Li, Jun Ma, Wu-Yin Jin
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    ABSTRACT: In this paper, the synchronization of certain degenerate optical parametric oscillators is investigated in detail. Complete and/or partial synchronization can be reached when linear controller, constructed by the real part or imaginary part of the subharmonic mode, is imposed on the chaotic degenerate optical parametric oscillators with appropriate coupling intensity. The Lyapunov exponents under different coupling coefficients are calculated to find the critical condition for complete synchronization. Transition from complete synchronization to partial synchronization is observed when nonlinear coupling is introduced into the two chaotic oscillators. It is found that synchronization of chaotic oscillators keeps robust when the intensity of the nonlinear coupling is less than the intensity of the linear coupling; the complete synchronization state is destructed and transient period for partial synchronization is in certain delay when the intensity of the nonlinear coupling is beyond the intensity of the linear coupling.
    Applied Mathematics and Computation. 01/2010;
  • Jun Ma, Chun-Ni Wang, Wu-Yin Jin, Ying Wu
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    ABSTRACT: Transition of spiral wave in the regular networks of Hodgkin–Huxley (H–H) neurons is simulated and discussed in detail when the effect of membrane temperature and forcing current is considered. Neurons are distributed in the sites of two-dimensional array, neurons are connected with complete nearest-neighbor connections, no-flux boundary conditions, appropriate initial values and physiological parameters are used to develop a stable rotating spiral wave. A statistic factor of synchronization is defined to discuss the transition and development of spiral wave in the two parameters space (membrane temperature T and forcing current I), and it is found that spiral wave keeps alive due to positive current forcing and the spiral wave can be removed completely when the temperature is increased to a threshold about T = 22.3 °C at a fixed current intensity. Periodical forcing current is imposed on the networks of neurons globally and locally, respectively. It is found that spiral wave could be suppressed by the new generated traveling wave or target wave when periodical forcing current is imposed on the border of networks of neurons, and the most effective frequency of the external forcing current is close to the intrinsic frequency of the spiral wave of the networks.
    Applied Mathematics and Computation. 01/2010;
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    Jun Ma, Chun-Ni Wang, Jun Tang, Ya-Feng Xia
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    ABSTRACT: Periodical forcing is used to control the spiral wave and turbulence in the modified Fithzhugh-Nagumo equation (MFHNe) when excitability is changed. The decisive parameter ε of (MFHNe), which describes the ratio of time scales of the fast activator u and the slow inhibitor variable v, is supposed to increase linearly to simulate the excitability modulation in the media. In the numerical simulation, a local periodical stimulus is imposed on the left border of the media and the periods of external forcing are adjusted according to the approximate formula ω ∝1/ε 1/3 so that using the most appropriate frequency for the external forcing can approach a shorter transient period. It is found that the spiral wave and turbulence can be removed successfully by using an appropriate periodical forcing on the left border of the media. The mean activator and distribution of frequency of all the sites are also used to analyze the transition of spiral wave.
    International Journal of Theoretical Physics 12/2008; 48(1):150-157. · 1.09 Impact Factor
  • Jun Ma, Ji-Hua Gao, Chun-Ni Wang, Jun-Yan Su
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    ABSTRACT: In this letter, scheme is proposed to suppress the spiral wave and multi-spiral waves in the complex Ginzburg–Landau equation (CGLE) under a local feedback control, which the perturbation is imposed on a small square area about 3×33×3 grids in the center of the media under periodical boundary conditions and 5×55×5 grids in the boundary of the media under no-flux conditions. Starting from random and/or perpendicular-gradient initial conditions, and the periodical boundary condition and/or no-flux boundary condition is in consideration, respectively. The numerical simulation results show that a target wave appears as the feedback began to work and the spiral and multi-spiral waves are overcome by the new generated target wave, furthermore, it confirms its effectiveness even if the spatiotemporal noise is introduced into the whole media.
    Chaos Solitons & Fractals 10/2008; 38(2):521–530. · 1.25 Impact Factor
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    Jun Ma, Ya Jia, Chun-Ni Wang, Shi-Rong Li
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    ABSTRACT: There are some similarities between the spiral wave in excitable media and in cardiac tissue. Much evidence shows that the appearance and instability of the spiral wave in cardiac tissue can be linked to one kind of heart disease. There are many models that can be used to investigate the formation and instability of the spiral wave. Cardiac tissue is excitable and elastic, and it is interesting to simulate the transition and instability of the spiral wave induced by media deformation. For simplicity, a class of the modified Fitzhugh–Nagumo (MFHN) model, which can generate a stable rotating spiral wave, meandering spiral wave and turbulence within appropriate parameter regions, will be used to simulate the instability of the spiral wave induced by the periodical deformation of media. In the two-dimensional case, the total acreage of elastic media is supposed to be invariable in the presence of deformation, and the problem is described with Lx × Ly = N × ΔxN × Δy = L'xL'y = N × Δx'N × Δy'. In our studies, elastic media are decentralized into N × N sites and the space of the adjacent sites is changed to simulate the deformation of elastic media. Based on the nonlinear dynamics theory, the deformation effect on media is simplified and simulated by perturbing the diffusion coefficients Dx and Dy with different periodical signals, but the perturbed diffusion coefficients are compensatory. The snapshots of our numerical results find that the spiral wave can coexist with the spiral turbulence, instability of the spiral wave and weak deformation of the spiral wave in different conditions. The ratio parameter ε and the frequency of deformation forcing play a deterministic role in inducing instability of the spiral wave. Extensive studies confirm that the instability of the spiral wave can be induced and developed only if an appropriate frequency for deformation is used. We analyze the power spectrum for the time series of the mean activator of four sampled sites which are selected symmetrically in different cases, such as the condition that the spiral wave coexists with the spiral turbulence, spiral wave without evident deformation, complete instability of the spiral wave (turbulence) and weak deformation of the spiral wave. It is found that more new peaks appear in the power spectrum and the distribution of frequency becomes sparser when the spiral wave encounters instability.
    Journal of Physics A Mathematical and Theoretical 08/2008; 41(38):385105. · 1.77 Impact Factor
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    Jun Ma, Chun-Ni Wang, Yan-Long Li, Shi-Rong Li
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    ABSTRACT: Evolution of spiral waves in light-sensitive media described with the two variable oregonator model is investigated. The intensity of external illumination is modulated by a weak chaotic signal, which is introduced into the whole system, the additional bromide production is influenced and the dynamics thus changed. The results are confirmed within our numerical simulation and it may give useful information in pattern formation and suppression of spiral waves. It can be an example for anti-control of chaos.
    Chaos Solitons & Fractals 01/2007; · 1.25 Impact Factor