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一个四维超混沌系统的异构混沌同步参数识别及仿真
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作者 杨晓亚 何万生 《河北师范大学学报(自然科学版)》 CAS 北大核心 2013年第3期245-249,共5页
以非线性陀螺系统作为响应系统,研究了一个四维超混沌系统的异构混沌同步.对系统的基本性质进行了分析,通过吸引子图、分岔图及Lyapunov指数谱表征了系统在所取定的参数范围内的动力学行为.为了实现四维系统的异构同步,采用自适应同步... 以非线性陀螺系统作为响应系统,研究了一个四维超混沌系统的异构混沌同步.对系统的基本性质进行了分析,通过吸引子图、分岔图及Lyapunov指数谱表征了系统在所取定的参数范围内的动力学行为.为了实现四维系统的异构同步,采用自适应同步法为系统设计了合适的控制器,实现了系统在参数未知情况下的混沌同步及参数识别. 展开更多
关键词 四维超混沌系统 非线性陀螺系统 自适应同步法 混沌同步
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An adaptive blind watermarking scheme utilizing neural network for synchronization 被引量:1
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作者 吴健珍 谢剑英 杨煜普 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2007年第2期281-286,共6页
An important problem constraining the practical implementation of robust watermarking technology is the low robustness of existing algorithms against geometrical distortions. An adaptive blind watermarking scheme util... An important problem constraining the practical implementation of robust watermarking technology is the low robustness of existing algorithms against geometrical distortions. An adaptive blind watermarking scheme utilizing neural network for synchronization is proposed in this paper,which allows to recover watermark even if the image has been subjected to generalized geometrical transforms. Through classification of image’s brightness, texture and contrast sensitivity utilizing fuzzy clustering theory and human visual system, more robust watermark is adaptively embedded in DWT domain. In order to register rotation, scaling and translation parameters, feedforward neural network is utilized to learn image geometric pattern represented by six combined low order image moments. The distortion can be inverted after determining the affine distortion applied to the image and watermark can be extracted in a standard way without original image. It only needs a trained neural network. Experimental results demonstrate its advantages over previous method in terms of computational effectiveness and parameter estimation accuracy. It can embed more robust watermark under certain visual distance, and effectively resist JPEG compression, noise and geometric attacks. 展开更多
关键词 digital watermark image moment geometric attack DWT fuzzy clustering
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