Chen Zengqiang

The generation of a hyperchaotic system based on a three-dimensional autonomous chaotic system

This paper reports a new four-dimensional hyperchaotic system obtained by adding a controller to a three-dimensional autonomous chaotic system. The new system has two parameters and each equation of the system has one quadratic cross-product term. Some basic properties of the new system are analysed. The different dynamic behaviours of the new system are studied when the system parameter a or b is varied. The system is hyperchaotic in several different regions of the parameter b. Especially, the two positive Lyapunov exponents are both larger and the hyperchaotic region is also larger when this system is hyperchaotic in the case of varying a. The hyperchaotic system is analysed by Lyapunov-exponents spectrum, bifurcation diagrams and Poincare sections.

Constrained predictive control based on T-S fuzzy model for nonlinear systems

Abstract A constrained generalized predictive control (GPC) algorithm based on the T-S fuzzy model is presented for the nonlinear system. First, a Takagi-Sugeno (T-S) fuzzy model based on the fuzzy cluster algorithm and the orthogonal least square method is constructed to approach the nonlinear system. Since its consequence is linear, it can divide the nonlinear system into a number of linear or nearly linear subsystems. For this T-S fuzzy model, a GPC algorithm with input constraints is presented. This strategy takes into account all the constraints of the control signal and its increment, and does not require the calculation of the Diophantine equations. So it needs only a small computer memory and the computational speed is high. The simulation results show a good performance for the nonlinear systems.

A Chaotic Images Encryption Algorithm with the Key Mixing Proportion Factor

The pseudo random property of chaotic sequences is very useful in the field of information security, based on the idea of orbit hopping, a chaotic image encryption algorithm with a key mixing proportion factor is proposed. In the proposed algorithm the position scrambling matrix and the value scrambling matrix are generated by the improved chaotic logistic sequences. A key mixing proportion factor (KMPF) is generated based on the plaintext information. By adding this factor, most of cipher text elements value can be changed by the change of any plaintext element. The Security of the proposed algorithm is improved with this factor, and the ability of the proposed algorithm resisting plaintext attacks is strengthened obviously, and the encryption algorithm can resist the statistical and differential attacks effectively, moreover, the algorithm has a large key space and high encryption speed. The effectiveness of the proposed algorithm is verified by the theoretical analysis and numerical simulations.

A novel four-wing chaotic attractor generated from a three-dimensional quadratic autonomous system ⁄

This paper presents a new 3D quadratic autonomous chaotic system which contains flve system parameters and three quadratic cross-product terms, and the system can generate a single four-wing chaotic attractor with wide parameter ranges. Through theoretical analysis, the Hopf bifurcation processes are proved to arise at certain equilibrium points. Numerical bifurcation analysis shows that the system has many interesting complex dynamical behaviours; the system trajectory can evolve to a chaotic attractor from a periodic orbit or a flxed point as the proper parameter varies. Finally, an analog electronic circuit is designed to physically realize the chaotic system; the existence of four-wing chaotic attractor is verifled by the analog circuit realization.

Dynamic spreading behavior of homogeneous and heterogeneous networks

Abstract The detailed investigation of the dynsmic epidemic spreading on homogeneous and heteiogeneous networks was carried out. After the analysis of the basic epidemic models, the susceptible-infected-susceptible (SIS) model on homogenous and heterogeneous networks is established, and the dynamical evolution of the density of the infected individuals in these two different kinds of networks is analyzed theoretically. It indicates that heterogeneous networks sre easier to piopagate for the epidemics and the leading spreading behavior is dictated by the exponential increasing in the initial outbreaks. Large-scale simulations display that the infection is much faster on heterogeneous networks than that on homogeneous ones. It means that the network topology can have a significant effect on the epidemics taking place on complex networks. Some containment sfrategies of epidemic outbreaks sre presented according to the theoretical analyses and numerical simulations. * Supported by National Natural Science Fou...

Local bifurcation analysis of a four-dimensional hyperchaotic system

Local bifurcation phenomena in a four-dimensional continuous hyperchaotic system, which has rich and complex dynamical behaviours, are analysed. The local bifurcations of the system are investigated by utilizing the bifurcation theory and the centre manifold theorem, and thus the conditions of the existence of pitchfork bifurcation and Hopf bifurcation are derived in detail. Numerical simulations are presented to verify the theoretical analysis, and they show some interesting dynamics, including stable periodic orbits emerging from the new fixed points generated by pitchfork bifurcation, coexistence of a stable limit cycle and a chaotic attractor, as well as chaos within quite a wide parameter region.

A dynamic epidemic control model on uncorrelated complex networks

In this paper, a dynamic epidemic control model on the uncorrelated complex networks is proposed. By means of theoretical analysis, we found that the new model has a similar epidemic threshold as that of the susceptible-infected-recovered (SIR) model on the above networks, but it can reduce the prevalence of the infected individuals remarkably. This result may help us understand epidemic spreading phenomena on real networks and design appropriate strategies to control infections.

A novel hyperchaos evolved from three dimensional modified Lorenz chaotic system

This paper reports a new four-dimensional continuous autonomous hyperchaos generated from the Lorenz chaotic system by introducing a nonlinear state feedback controller. Some basic properties of the system are investigated by means of Lyapunov exponent spectrum and bifurcation diagrams. By numerical simulating, this paper verifies that the four-dimensional system can evolve into periodic, quasi-periodic, chaotic and hyperchaotic behaviours. And the new dynamical system is hyperchaotic in a large region. In comparison with other known hyperchaos, the two positive Lyapunov exponents of the new system are relatively more larger. Thus it has more complex degree.

A tracking control scheme for leader based multi-agent consensus for discrete-time case

A new leader-guarding consensus problem for heterogeneous multi-agent system with switching topology in discrete-time domain is investigated. First, a new discrete-time model of heterogeneous and mobile multi-agent system with a motile leader and variable topology is established, where the location information of the active leader is completely known but the acceleration information may not be measured. A neighbor-based pinning control law and a neighbor-based state-estimation rule are proposed for solving the consensus problem. Such consensus protocols under the requirement of virtual connected guarantee that each follower-agent can estimate the leaderpsilas velocity and then track it in a bounded area if the acceleration input of the leader is unknown, where the tracking error can be estimated based on Lyapunov approach.

Implementation of LT codes based on chaos

Fountain codes provide an efficient way to transfer information over erasure channels like the Internet. LT codes are the first codes fully realizing the digital fountain concept. They are asymptotically optimal rateless erasure codes with highly efficient encoding and decoding algorithms. In theory, for each encoding symbol of LT codes, its degree is randomly chosen according to a predetermined degree distribution, and its neighbours used to generate that encoding symbol are chosen uniformly at random. Practical implementation of LT codes usually realizes the randomness through pseudo-randomness number generator like linear congruential method. This paper applies the pseudo-randomness of chaotic sequence in the implementation of LT codes. Two Kent chaotic maps are used to determine the degree and neighbour(s) of each encoding symbol. It is shown that the implemented LT codes based on chaos perform better than the LT codes implemented by the traditional pseudo-randomness number generator.