Detection of dynamical structure from short and noisy chaotic series.

A method is proposed to detect the dynamical structure hiding behind complex chaotic series by comparing prediction performance of trial functions. This method is valid even when the original system is contaminated with noise or only a relatively short data series is recorded. Using this method, the dynamical structure of the Gray-Scott model is detected from its rich spatiotemporal patterns. Finally, this method is successfully applied to the experimental data of Chua's circuit, which promises its potential of the application to realistic systems.

Synchronized pseudorandom systems and their application to speech communication.

An approach to the synchronization of pseudorandom systems is proposed and applied to secure speech communication. The encoding signal produced by the pseudorandom synchronization scheme passes the random test, and shows much more complex dynamics, better random properties, and greater sensitivity to parameter mismatches than that produced by the active-passive decomposition scheme. Also, two coupled pseudorandom systems can be exactly synchronized despite their different initial states or seeds. Pseudorandom encoding and synchronization may yield great security in communication.

Estimating model parameters by chaos synchronization.

Using chaos synchronization and a proposed iterative method of parameter adaptation, we precisely estimate the model parameters of chaotic systems and synchronize two chaotic systems with originally mismatching model parameters. This parameter adaptation method can be applied to a spatiotemporal chaotic system with a one-way-coupled map lattice. As a biomedical application, this method is capable of estimating the asymmetric tension parameter of a vocal fold model.

The shock formation distance in a bounded sound beam of finite amplitude.

This paper investigates the shock formation distance in a bounded sound beam of finite amplitude by solving the Khokhlov-Zabolotskaya-Kuznetsov (KZK) equation using frequency-domain numerical method. Simulation results reveal that, besides the nonlinearity and absorption, the diffraction is another important factor that affects the shock formation of a bounded sound beam. More detailed discussions of the shock formation in a bounded sound beam, such as the waveform of sound pressure and the spatial distribution of shock formation, are also presented and compared for different parameters.