In this paper, a new two-dimensional sine-cosine coupling chaos map(2D-SCCM) is proposed. The performance of the proposed two-dimensional chaotic system is analysed by using trajectory distribution maps, Lyapunov exponents, sample entropy and sequence sensitivity, etc. The results show that the 2D-SCCM has better randomness and ergodicity, as well as a wider hyperchaotic range than the existing partial two-dimensional chaos maps. To verify its application in practice, a 2D-SCCM-based color image encryption algorithm is proposed. First, the plain image is used to combine with hash function to generate the key. Then, we construct S-Boxes using the random sequence generated by 2D-SCCM combined with Arnold map. Finally, a color image encryption algorithm is proposed by using the constructed S-Boxes and the chaotic map combined with hash function. Experimental simulations and security tests show that the proposed encryption algorithm has high encryption efficiency and strong security, and can effectively protect images from various attacks.
A multiscale cooperative differential evolution algorithm is proposed to solve the problems of narrow search range at the early stage and slow convergence at the later stage in the performance of the traditional differential evolution algorithms. Firstly, the population structure of multipopulation mechanism is adopted so that each subpopulation is combined with a corresponding mutation strategy to ensure the individual diversity during evolution. Then, the covariance learning among populations is developed to establish a suitable rotating coordinate system for cross operation. Meanwhile, an adaptive parameter adjustment strategy is introduced to balance the population survey and convergence. Finally, the proposed algorithm is tested on the CEC 2005 benchmark function and compared with other state-of-the-art evolutionary algorithms. The experiment results showed that the proposed algorithm has better performance in solving global optimization problems than other compared algorithms.
In this paper, the synchronization problem of Chen systems with time-varying delays is discussed based on the stability theory of time-delay systems. Through the analysis of the error dynamical systems, the time-delay correlative synchronization controller is designed to achieve chaos synchronization. And finally, numerical simulations are provided to verify the effectiveness and feasibility of the developed method.
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