A simple iterative independent component analysis algorithm for vibration source signal identification of complex structures

ABSTRACT:Independent Component Analysis (ICA), one of the blind source separation methods, can be applied for extracting unknown source signals only from received signals. This is accomplished by finding statistical independence of signal mixtures and has been successfully applied to myriad fields such as medical science, image processing, and numerous others. Nevertheless, there are inherent problems that have been reported when using this technique: insta- bility and invalid ordering of separated signals, particularly when using a conventional ICA technique in vibratory source signal identification of complex structures. In this study, a simple iterative algorithm of the conventional ICA has been proposed to mitigate these problems. The proposed method to extract more stable source signals having valid order includes an iterative and reordering process of extracted mixing matrix to reconstruct finally converged source signals, referring to the magnitudes of correlation coefficients between the intermediately separated signals and the signals measured on or nearby sources. In order to review the problems of the conventional ICA technique and to vali- date the proposed method, numerical analyses have been carried out for a virtual response model and a 30m class submarine model. Moreover, in order to investigate applicability of the proposed method to real problem of complex structure, an experiment has been carried out for a scaled submarine mockup. The results show that the proposed method could resolve the inherent problems of a conventional ICA technique

Adaptive Blind Watermarking Algorithm Based on ICA and DWT

为了使数字水印具有较强的鲁棒性和不可见性,提出一种基于独立分量分析(ICA)和离散小波变换(dWT)的自适应鲁棒性盲水印算法.该算法先将载体图像进行小波变换,然后将原始水印进行平铺和置乱,再根据噪声可见函数(nVf)的视觉掩蔽作用,将其自适应地嵌入到载体图像小波变换域的低频系数上,最后利用ICA技术实现了水印盲提取.实验结果表明,该算法的水印不可见性较好,且可抵抗多种常见水印攻击,其中对JPEg压缩、尺度缩放等攻击的鲁棒性较突出,可应用于图像的版权保护.In order to enhance the robustness and invisibility of digital watermarking,a new adaptive watermarking algorithm based on independent component analysis(ICA) and discrete wavelet transform(DWT) is proposed.The algorithm firstly decomposes the image into wavelet domain.Then the watermark is adaptive embedded into its low frequency coefficient,under the visual mask of noise visibility function(NVF),which has been rearranged by tiling extended and scramble before embedded.It realizes blind extraction by ICA.Experimental results show that the algorithm has good transparency and better robustness,especially in JPEG compression and resizing scale attacks.It can be applicable for digital image copyright protection.福建省自然科学基金项目(2010J01210