利用非线性自适应技术检测微弱的瞬时信号

本文根据局部流形理论,提出了一类非线性自适应预测滤波模型。仿真结果显示,本文提出的自适应预测滤波模型具有很强的非线性近似能力,可以检测淹没在超混沌或杂波环境中的瞬时信号。     

A twin‐star hyperchaotic attractor and its circuit implementation

A very simple 4D system with a twin‐star hyperchaotic attractor is presented in this letter. Computer simulation is given to visualize the attractor, and a simple circuitry is designed for system implementation. Copyright © 2003 John Wiley & Sons, Ltd.     

超混沌系统的控制

将反馈精确线性化的方法用于超混沌用于超混沌系统的控制。并针对超混沌Ｒｏｓｓｌｅｒ设计了控制器,使该系统实现了全局稳定（稳化）,同时还能实现对原系统的任意不稳定平衡点和周期信号的稳态跟踪。仿真结果证实了此方法的有效性,并且数值分析了闭环系统的鲁棒性。     

Hyperchaotic behaviour of two bi‐directionally coupled Chua's circuits

In this paper, a non‐linear bi‐directional coupling of two Chua's circuits is presented. The coupling is obtained by using polynomial functions that are symmetric with respect to the state variables of the two Chua's circuits. Both a transverse and a tangent system are studied to ensure a global validity of the results in the state space. First, it is shown that the transverse system is an autonomous Chua's circuit, which directly allows the evaluation of the conditions on its chaotic behaviour, i.e. the absence of synchronization between the coupled circuits. Moreover, it is demonstrated that the tangent system is also a Chua's circuit, forced by the transverse system; therefore, its dynamics is ruled by a time‐dependent equation. Thus, the calculus of conditional Lyapunov exponents is necessary in order to exclude antisynchronization along the tangent manifold. The properties of the transverse and tangent systems simplify the study of the coupled Chua's circuits and the determination of the conditions on their hyperchaotic behaviour. In particular, it is shown that hyperchaotic behaviour occurs for proper values of the coupling strength between the two Chua's circuits. Finally, numerical examples are given and discussed. Copyright © 2002 John Wiley & Sons, Ltd.     

一类超混沌系统的广义同步研究

研究了一类四维超混沌系统的广义同步问题，基于稳定性理论得到控制器的解析表达式，分别实现了相同结构和异结构超混沌系统的广义同步，全局同步和相同步。数值计算与理论分析一致。     

一种超混沌自动转换系统的设计与分析

在一种超混沌系统的基础上,通过改变系统第三个方程中的非线性项的方法,构造了一个新的超混沌系统,并利用常用开关函数来实现超混沌自动转换系统。通过matlab对超混沌系统进行仿真,产生超混沌吸引子,并对其子系统和转换系统Lyapunov指数进行分析与研究,仿真满足超混沌系统产生必要条件。结果表明所设计的自动转换系统可以实现两个超混沌系统的相互转换。     

Hyperchaos evolved from the generalized Lorenz equation

In this letter, a new hyperchaotic system is formulated by introducing an additional state into the third‐order generalized Lorenz equation. The existence of the hyperchaos is verified with bifurcation analysis, and the bifurcation routes from periodic, quasi‐periodic, chaotic and hyperchaotic evolutions are observed. Various attractors are illustrated not only by computer simulation but also by the realization of an electronic circuit. Copyright © 2005 John Wiley & Sons, Ltd.     

Design and experimental confirmation of a novel switched hyperchaotic system

To generate complex pseudo-noise (PN) sequences for chaos-based communications, this article presents a novel switched hyperchaotic model, which is constructed based on a modified Chen system by introducing a dynamical controller. The system consists of two different hyperchaotic subsystems and can change its behavior randomly via a switching function. Basic dynamical behaviors of the hyperchaotic system are further investigated. Furthermore, the switched system is confirmed by its positive Lyapunov exponents and laboratory measurements by an electronic circuit.     

Heterogeneous Memristive Models Design and Its Application in Information Security

Based on the three-dimensional classic Chua circuit, a nonlinear circuit containing two flux-control memristors is designed. Due to the difference in the design of the characteristic equation of the two magnetron memristors, their position form a symmetrical structure with respect to the capacitor. The existence of chaotic properties is proved by analyzing the stability of the system, including Lyapunov exponent, equilibrium point, eigenvalue, Poincare map, power spectrum, bifurcation diagram et al. Theoretical analysis and numerical calculation show that this heterogeneous memristive model is a hyperchaotic five-dimensional nonlinear dynamical system and has a strong chaotic behavior. Then, the memristive system is applied to digital image and speech signal processing. The analysis of the key space, sensitivity of key parameters, and statistical character of encrypted scheme imply that this model can applied widely in multimedia information security.     

超混沌Lorenz系统的线性与非线性耦合同步

通过理论分析与数值仿真,分别实现了一类超混沌系统的线性与非线性反馈控制耦合同步．利用超混沌系统的最大Lyapunov指数确定反馈控制系数需满足的取值范围,实现线性耦合同步．对于非线性耦合同步,则是基于对Lyapunov方法的理论讨论,给出超混沌系统在全局范围内实现同步的充分条件．