Zhong Liu

A SIMPLE MEMRISTOR CHAOTIC CIRCUIT WITH COMPLEX DYNAMICS

A simple memristor-based chaotic circuit with an active flux-controlled memristor characterized by a smooth continuous cubic nonlinearity is designed. The proposed chaotic circuit can generate a 2-scroll chaotic attractor on a finite time scale and has an equilibrium set with its stability dependent on the initial state of the memristor. The complex dynamics of the proposed chaotic circuit under different initial state of the memristor are investigated both theoretically and numerically. In particular, some novel transient transition behaviors with different time scales are found in the memristor circuit. Experimental observations based on a universal circuit implementation platform are conducted to partially verify the numerical simulation results.

Unified Classification of Operation-State Regions for Switching Converters with Ramp Compensation

With the variation of circuit parameters, the operation-state regions of current-mode-controlled switching dc-dc converters can shift among stable period region, robust chaos region in continuous conduction mode, and intermittent chaos region in discontinuous conduction mode. This paper presents a unified approach to the operation-states analysis of switching dc-dc converters with ramp compensation. The piecewise map model of the converters is first derived. With the bifurcation analyses, two boundary classification equations of the orbit state shifting are then obtained. Finally, the operation-state regions are well classified. To verify the theoretical analysis results, 2-D bifurcation diagrams are simulated and experimentations with current-mode-controlled buck converter are conducted. It is revealed that regular and irregular (chaotic or intermittent) operation states can be generated depending on circuit parameters or control of ramp-compensation current.

MULTISCROLL CHAOTIC ATTRACTORS FROM A MODIFIED COLPITTS OSCILLATOR MODEL

A simple approach for generating (2N + 1)-scroll chaotic attractor from a modified Colpitts oscillator model is proposed in this paper. The key strategy is to increase the number of index-2 equilibrium points by introducing a triangle function to directly replace the nonlinearity term of Colpitts oscillator model. The dynamical characteristics of the new multiscroll chaotic system are studied comprehensively. A circuit realization structure is introduced and the experimental results demonstrate that (2N + 1)-scroll chaotic attractors can be obtained in practical circuit.

Generating multi-scroll chaotic attractor from a linear system driven by saturated function series

A novel approach for generating multi-scroll chaotic attractor from a three-dimensional linear system is presented in this paper. (2N+1)×(2M+1)-grid scroll, (2N+1)-scroll and (2M+1)-scroll chaotic attractor can be formulated by an unstable three-dimensional linear system driven by two saturated function series. The new multi-scroll chaotic system is comprehensively analyzed based on its even and odd equilibrium points as well as its corresponding characteristic equations. A circuit implementation is introduced and the experimental result demonstrates that the multi-scroll chaotic attractor, with 7×7-grid scrolls and 9×9-grid scrolls, can be obtained in practical circuit.

HYPERCHAOS FROM AN AUGMENTED LÜ SYSTEM

This letter introduces a hyperchaotic system from the Lu system [Lu et al., 2004] with a linear state feedback controller. This hyperchaotic system has more complex dynamical behaviors, and can generate 4-scroll hyperchaotic attractor and 2-scroll chaotic attractor under different control parameters. In particular, the system can also exhibit novel coexisting intermittent chaotic orbits. Theoretical analyses and simulation experiments are conducted to investigate the dynamical behaviors of the proposed hyperchaotic system.

Adaptive distributed Estimation Fusion algorithm based on the Consensus Averaging algorithm

This paper focuses on the distributed iterative parameter estimation scheme, based on the consensus averaging algorithm, for estimating an unknown parameter from the noisy measurements. A new spatio-temporal adaptive algorithm, called the Consensus Averaging-based Adaptive Estimation Fusion (CA-AEF) algorithm is proposed, which accelerates the convergence rate of the current distributed iterative scheme. This algorithm models each node as an adaptive filter, and the performance improvement is achieved by introducing an adaptive weight updating method. Simulation results show that the proposed algorithm largely improves the convergence rate of the distributed parameter estimation, and also improve the estimation accuracy.

Generalized projective synchronization of n-Scroll chaotic jerk system

Multi-scroll chaotic system has found important applications as broadband signal generator and true pseudorandom number generator for communication engineering. In this paper, an active control method is proposed to projective-synchronize two n-scroll chaotic Jerk systems. The proposed technique is applied to achieve generalized projective synchronization for the chaotic system, where all state variables are in a proportional way. This characteristic allows us to direct the scaling factor arbitrarily onto a desired value. Feasibility of the proposed control scheme is illustrated through the numerical examples.

Controlling double-scroll chaotic Lü attractor to difformity

By adding a linear control circuit into a chaotic Lü system, a double-scroll chaotic Lü attractor can be controlled by adjusting control parameters to obtain several difform attractors, such as four-scroll attractor, novel double-scroll attractor and spiral attractor, etc., which implies that the new circuit can generate different chaos signal under different control parameters. The proposed control circuit is very simple, with integration and addition function implemented by two operational amplifiers. These difform chaotic attractors along with periodic limit cycles are obtained from simulation of the new circuit and mathematics calculation of the corresponding system equations. The detailed dynamical behaviors of this four-dimensional continuous autonomous dissipative chaotic system, including Lyapunov exponent spectrum, bifurcation diagram, Poincaré mapping and phase portrait, etc., are investigated.

Modelling and prediction of cyclostationary chaotic time series using periodic autoregressive models

It has been shown that some chaotic time series have cyclostationary characteristics. In this paper, this characteristic is exploited for applications to modeling and prediction of chaotic time series. To this aim, the periodic autoregressive model is used. The application of the proposed model to simulated data from the periodically perturbed logistic map is carried out and the results show that the model works well for modelling and long-term prediction in comparison with other models.