A hyperchaos-based watermarking algorithm is developed in the wavelet domain for images.The algorithm is based on discrete wavelet transform and combines the communication model with side information.We utilize a suit...A hyperchaos-based watermarking algorithm is developed in the wavelet domain for images.The algorithm is based on discrete wavelet transform and combines the communication model with side information.We utilize a suitable scale factor to scale host image,then construct cosets for embedding digital watermarking according to scale version of the host image.Our scheme makes a tradeoff between imperceptibility and robustness,and achieves security.The extraction algorithm is a blind detection algorithm which retrieves the watermark without the original host image.In addition,we propose a new method for watermark encryption with hyperchaotic sequence.This method overcomes the drawback of small key space of chaotic sequence and improves the watermark security.Simulation results indicate that the algorithm is a well-balanced watermarking method that offers good robustness and imperceptibility.展开更多
The non-uniform transmission and network topological structure are combined to investigate the spreading behavior of susceptible-infected-susceptible （SIS） epidemic model. Based on the mean-field theory, the analyti...The non-uniform transmission and network topological structure are combined to investigate the spreading behavior of susceptible-infected-susceptible （SIS） epidemic model. Based on the mean-field theory, the analytical and numerical results indicate that the epidemic threshold is correlated with the topology of underlying networks, as well as the disease transmission mechanism. These discoveries can greatly help us to further understand the virus propagation on communication networks.展开更多
基金Supported by National Natural Science Foundation of China(60574036) ,the Specialized Research Fund for the Doctoral Pro-gramof Higher Education of China (20050055013) ,and the program for New Century Excellent Talents in University of China(NCET) .
文摘A hyperchaos-based watermarking algorithm is developed in the wavelet domain for images.The algorithm is based on discrete wavelet transform and combines the communication model with side information.We utilize a suitable scale factor to scale host image,then construct cosets for embedding digital watermarking according to scale version of the host image.Our scheme makes a tradeoff between imperceptibility and robustness,and achieves security.The extraction algorithm is a blind detection algorithm which retrieves the watermark without the original host image.In addition,we propose a new method for watermark encryption with hyperchaotic sequence.This method overcomes the drawback of small key space of chaotic sequence and improves the watermark security.Simulation results indicate that the algorithm is a well-balanced watermarking method that offers good robustness and imperceptibility.
基金supported by the National Natural Science Foundation of China (60574036, 60774088)the Research Fund for the Doctoral Program of China (20050055013)+2 种基金the Program for New Century Excellent Talents in University of China (NCET)Tianjin Municipal Natural Science Foundation (08JCZDJC21900,08ZCKFGX00600, 08JCYBJC12300)Tianjin Municipal Research Foundation for the Universities (20071306).
文摘The non-uniform transmission and network topological structure are combined to investigate the spreading behavior of susceptible-infected-susceptible （SIS） epidemic model. Based on the mean-field theory, the analytical and numerical results indicate that the epidemic threshold is correlated with the topology of underlying networks, as well as the disease transmission mechanism. These discoveries can greatly help us to further understand the virus propagation on communication networks.
