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Daihai He

Publications and source records attributed to Daihai He.

6 recordsLinked to original sources
PubMed2003

Unexpected correspondence between noise-induced and master-slave complete synchronizations.

A comparison between noise-induced synchronization and master-slave (Pecora-Carroll) synchronization is investigated in this paper. We find an interesting correspondence between the effective driving variables of these two kinds of synchronizations in three-dimensional chaotic systems, when the systems have nonlinear terms in more than one equation. A study of the Lorenz model, the Hindmarsh-Rose neuron model, and the Hastings-Powell foodweb model is given to support this claim. It is a somewhat surprising result since these two kinds of synchronizations arise through different mechanisms. We also examine an exceptional case, where the nonlinear term of the system appears in a single equation, as in the Pikovsky-Rabinovich circuit model, and explain why the correspondence fails.

Journal Article↗
PubMed2003

Spatio-temporal synchronization of recurrent epidemics.

Long-term spatio-temporal datasets of disease incidences have made it clear that many recurring epidemics, especially childhood infections, tend to synchronize in-phase across suburbs. In some special cases, epidemics between suburbs have been found to oscillate in an out-of-phase ('antiphase') relationship for lengthy periods. Here, we use modelling techniques to help explain the presence of in-phase and antiphase synchronization. The nonlinearity of the epidemic dynamics is often such that the intensity of the outbreak influences the phase of the oscillation thereby introducing 'shear', a factor that is found to be important for generating antiphase synchronization. By contrast, the coupling between suburbs via the immigration of infectives tends to enhance in-phase synchronization. The emerging synchronization depends delicately on these opposite factors. We use theoretical results from continuous time models to provide a framework for understanding the relationship between synchronization patterns for different model structures.

Computer Simulation↗
PubMed2003

Detecting generalized synchrony: an improved approach.

We examine some of the difficulties involved in detecting generalized synchrony (GS) in systems that exhibit noninvertibility and/or wrinkling. These latter features severely hinder identification of GS by conventional techniques. It is shown that it is possible to greatly improve detection by reducing the pseudofalse neighbors effects. Here we propose the delta(p)-neighbor method to overcome the noninvertibility effect and the delta(p,q) method to detect GS in systems with wrinkled structures.

Journal Article↗
PubMed2003

Noise-induced synchronization in realistic models.

Noise-induced synchronization is studied numerically in two realistic models--the Pikovsky-Rabinovich circuit model and the Hindmarsh-Rose neuron model. A different feature, single-variable-Jacobian matrix, is found in these two models and conditions are found by which two noncoupled identical systems can been synchronized by forcing with a common Gaussian noise term.

Journal Article↗
PubMed2002

Pattern formation of spiral waves in an inhomogeneous medium with small-world connections.

Pattern formation of spiral waves in an inhomogeneous excitable medium with small-world connections is investigated. In both cases, with completely local regular connections and with completely random connections, spiral waves cannot survive in the given inhomogeneous medium. It is found that with small-world connections (basically local connections plus a small number of random connections) a well behaved spiral wave can be formed against the destructive role of the inhomogeneous medium. There also exists an optimal fraction of random connections which can greatly enhance the probability of spiral wave formation; this resembles the behavior of stochastic resonance.

Journal Article↗