According to the anti-control principle of chaos, a combined control method is proposed based on a class of asymptotically stable linear systems with multiple controllers. A higher-dimensional hyperchaotic system is investigated by the Lyapunov exponents method and equilibrium points analysis, and it exists the largest number of positive Lyapunov exponents. The chaotic pseudo-random sequences of the higher-dimensional hyperchaotic system can pass all NIST tests after preprocess-ing, and behave better chaotic characteristics. Meanwhile, a new encryption algorithm of image information with position scrambling, sequential diffusion and reverse diffusion is designed based on the chaotic pseudo-random sequences. The experiments of image information are given to verify the effectiveness and feasibility of the encryption algorithm. Finally, the security analyses are also discussed by the key sensitivity, differential attack and statistical analysis. It is shown that the encryption algorithm has large enough key space and can be applied to secure communication.
The maintenance process model is a basic component for the virtual maintainability analysis and maintenance training. An extended Petri net was proposed in the modeling of equipment's maintenance task process. The expressions of the maintenance tasks relations and maintenance resources are discussed; the maintenance resource object token is proposed to enhance the description capability of the model, and the conditions of firing are defined. Finally, the feasibility of this model was demonstrated by a case of a typical maintenance process.
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