Narrow Results

Phase synchronization between linearly and nonlinearly coupled systems with internal resonance is investigated in this paper. By introducing the conception of phase for a chaotic motion, we tune the linear coupling parameter to obtain the two Rössler oscillators in a synchronized regime and analyze the effect of a nonlinear coupling on the phase synchronized state. It demonstrates that the detuning parameter σ between the two natural frequencies ω₁ and ω₂ affects phase dynamics, and with the increase of the nonlinear coupling strength, for the primary resonance, the effect of phase synchronization between two sub-systems was decayed, while increasing with frequency ratio 1:2. Further investigation reveals that the transition of phase states between the two oscillators are related to the critical changes of the nonlinear coupling strength.

Phase synchronization of parametric excited Rössler system has been investigated in this paper. By introducing the conception of phase for a chaotic motion, it has been demonstrated that the mean frequency of chaotic attractor and the frequency of the parametric excitation may be locked in different ratios for certain parameter conditions, implying phase synchronization can be observed. The evolution from nonsynchronized state to phase synchronization has been discussed in detail, which reveals different phase dynamics may exist during the process. With the variation of parameters, the imaging point on the Poincaré plane may finally settle down onto the attractor, which yields phase synchronization.

In the present paper we show that inhomogeneity of a continuous self-sustained oscillating medium can be a reason for the onset of chaotic behavior. It has been established that temporal chaotic dynamics typically arises in the medium with a linear mismatch of the natural frequency along a spatial coordinate, whereas a chaotic regime is not characteristic for the medium with randomly distributed frequencies. The interconnection has been revealed between the temporal chaotic behavior and the spatial formation of imperfect clusters. The spectral and correlation analysis as well as the linear analysis of stability of regular and chaotic regimes in the inhomogeneous medium are performed. The correlation of the instantaneous phase dynamics of oscillations with the behavior of autocorrelation functions has been examined. It has been established that the characteristics of temporal chaos correspond to a spiral attractor (Shilnikov's attractor).

We study the behavior of an instantaneous phase and mean frequency of chaotic self-sustained oscillations and noise-induced stochastic oscillations. The results obtained by using various methods of the phase definition are compared to each other. We also compare two methods for describing synchronization of chaotic self-sustained oscillations, namely, instantaneous phase locking and locking of characteristic frequencies in power spectra. It is shown that the technique for diagnostics of the chaos synchronization based on the instantaneous phase locking is not universal.