Biomedical subjects

Meng Zhan

Publications and source records attributed to Meng Zhan.

9 recordsLinked to original sources

PubMed2005

Phase synchronization of a pair of spiral waves.

The interaction of a pair of spiral waves with different independent rotation frequencies is studied. In a very large frequency mismatch searching region, we observe three different pattern formation phenomena: (a) phase-synchronization-induced invasion under a relatively small frequency mismatch, i.e., the spiral wave with slower frequency (longer period) is swept away by a traveling wave, which is induced and phase synchronized by the faster spiral wave; (b) the coexistence of two spiral waves at sufficiently large parameter mismatch; and (c) an intermediate state, a non-phase-synchronous invasion, that is, similarly the slower spiral wave is swept by an approximate planar wave, whose frequency, however, is intermediate between those of the faster and slower waves. A point-source model is studied to analyze all these phenomena in a unified way.

Journal Article↗

PubMed2005

Public-key encryption based on generalized synchronization of coupled map lattices.

Currently used public-key cryptosystems are based on difficulties in solving certain numeric theoretic problems, in which the way to predict the private key from the knowledge of the public key is computationally infeasible. Here we propose a method of constructing public-key cryptosystems by generalized synchronization of coupled map lattices, in which the difficulty in predicting the synchronous function is used as the trap-door function to deduce the private key from the public key. In specific, we implement this idea on the method of "Merkle's puzzles," and find that, incorporated with the chaotic dynamics, this traditional method is equipped with some new features and can be practical in certain situations.

Journal Article↗

PubMed2004

Strange nonchaotic attractors in random dynamical systems.

Whether strange nonchaotic attractors (SNAs) can occur typically in dynamical systems other than quasiperiodically driven systems has long been an open question. Here we show, based on a physical analysis and numerical evidence, that robust SNAs can be induced by small noise in autonomous discrete-time maps and in periodically driven continuous-time systems. These attractors, which are relevant to physical and biological applications, can thus be expected to occur more commonly in dynamical systems than previously thought.

Logistic Models↗

PubMed2004

Error function attack of chaos synchronization based encryption schemes.

Different chaos synchronization based encryption schemes are reviewed and compared from the practical point of view. As an efficient cryptanalysis tool for chaos encryption, a proposal based on the error function attack is presented systematically and used to evaluate system security. We define a quantitative measure (quality factor) of the effective applicability of a chaos encryption scheme, which takes into account the security, the encryption speed, and the robustness against channel noise. A comparison is made of several encryption schemes and it is found that a scheme based on one-way coupled chaotic map lattices performs outstandingly well, as judged from quality factor.

Algorithms↗

PubMed2003

Complete synchronization and generalized synchronization of one-way coupled time-delay systems.

The complete synchronization and generalized synchronization (GS) of one-way coupled time-delay systems are studied. We find that GS can be achieved by a single scalar signal, and its synchronization threshold for different delay times shows the parameter resonance effect, i.e., we can obtain stable synchronization at a smaller coupling if the delay time of the driven system is chosen such that it is in resonance with the driving system. Near chaos synchronization, the desynchronization dynamics displays periodic bursts with the period equal to the delay time of the driven system. These features can be easily applied to the recovery of time-delay systems.

Journal Article↗

PubMed2002

Tailoring wavelets for chaos control.

Chaos is a class of ubiquitous phenomena and controlling chaos is of great interest and importance. In this Letter, we introduce wavelet controlled dynamics as a new paradigm of dynamical control. We find that by modifying a tiny fraction of the wavelet subspaces of a coupling matrix, we could dramatically enhance the transverse stability of the synchronous manifold of a chaotic system. Wavelet controlled Hopf bifurcation from chaos is observed. Our approach provides a robust strategy for controlling chaos and other dynamical systems in nature.

Journal Article↗

PubMed2002

Coherence resonance near the Hopf bifurcation in coupled chaotic oscillators.

We uncover a coherence resonance near the Hopf bifurcation from chaos in coupled chaotic oscillators. At the bifurcation, a nearly periodic rotating wave becomes stable as the state of synchronous chaos is destabilized. We find that noise can induce the bifurcation and, more strikingly, it can enhance the temporal regularity of the wave pattern in the coupled system. This resonant phenomenon is expected to be robust and physically observable.

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↗

PubMed2002

Transition from intermittency to periodicity in lag synchronization in coupled Rössler oscillators.

The dynamical and statistical behavior of lag synchronization in two coupled self-sustained chaotic Rössler oscillators is reexamined. The lack of uniqueness in the conventional characterization of lag synchronization based on the similarity function has caused much skepticism about the existence of lag synchronization. We provide an evidence that the emergence of lag synchronization is associated with the transition from on-off intermittency to a periodic structure in the laminar phase distribution.

Journal Article↗