供水管网存在大量分支接头,流体在分支接头的分流作用下产生支管流致噪声,并通过管道与泄漏声信号进行耦合。针对支管流致噪声存在下的供水管道泄漏定位问题。提出一种基于高效快速独立主成分分析(efficient fast independent component...供水管网存在大量分支接头,流体在分支接头的分流作用下产生支管流致噪声,并通过管道与泄漏声信号进行耦合。针对支管流致噪声存在下的供水管道泄漏定位问题。提出一种基于高效快速独立主成分分析(efficient fast independent component analysis,EFastICA)技术的复值域高效快速独立主成分分析(complex efficient fast independent component analysis,C-EFastICA)技术,该算法将时域瞬时线性EFastICA技术的代价函数、约束函数、迭代规则等有效地扩展到复数域,实现对含支管流致噪声的泄漏声信号分解处理。与其他主成分分析(independent component analysis,ICA)类算法固定选择非线性函数不同的是,C-EFastICA根据声信号的广义高斯性特征,自适应地选择非线性函数建立代价函数和迭代学习规则,使得算法对混合信号的分离程度更高。试验结果表明,泄漏信号和支管流致噪声均是超高斯信号,经C-EFastICA分解得到的源泄漏信号对漏点的定位相对误差低于12%,低于传统同类的C-FastICA技术。展开更多
This paper presents a robust color image hiding method based on YCbCr color system in discrete cosine transform （DOT） domain,which can hide a secret color image behind a public color cover image and is compatible wi...This paper presents a robust color image hiding method based on YCbCr color system in discrete cosine transform （DOT） domain,which can hide a secret color image behind a public color cover image and is compatible with the international image compression standard of JPEG. To overcome the grave distortion problem in the restored secret image,this paper proposes a new embedding scheme consisting of reasonable partition of a pixel value and sign embedding. Moreover, based on human visual system （HVS） and fuzzy theory,this paper also presents a fuzzy classification method for DOT sub-blocks to realize the adaptive selection of embedding strength. The experimental results show that the maximum distortion error in pixel value for the extracted secret image is ±1. And the color cover image can provide good quality after embedding large amount of data.展开更多
Modeling technique for electromagnetic fields excited by antennas is an important topic in computational electromagnetics, which is concerned with the numerical solution of Maxwell's equations. In this paper, a no...Modeling technique for electromagnetic fields excited by antennas is an important topic in computational electromagnetics, which is concerned with the numerical solution of Maxwell's equations. In this paper, a novel hybrid technique that combines method of moments(MoM) with finite-difference time-domain(FDTD) method is presented to handle the problem. This approach employed Huygen's principle to realize the hybridization of the two classical numerical algorithms. For wideband electromagnetic data, the interpolation scheme is used in the MoM based on the dyadic Green's function. On the other hand, with the help of equivalence principle, the scattered electric and magnetic fields on the Huygen's surface calculated by MoM are taken as the sources for FDTD. Therefore, the electromagnetic fields in the environment can be obtained by employing finite-difference time-domain method. Finally, numerical results show the validity of the proposed technique by analyzing two canonical samples.展开更多
基金This workis partially supported by National Science Foundation(Grant No.A0324676)
文摘This paper presents a robust color image hiding method based on YCbCr color system in discrete cosine transform （DOT） domain,which can hide a secret color image behind a public color cover image and is compatible with the international image compression standard of JPEG. To overcome the grave distortion problem in the restored secret image,this paper proposes a new embedding scheme consisting of reasonable partition of a pixel value and sign embedding. Moreover, based on human visual system （HVS） and fuzzy theory,this paper also presents a fuzzy classification method for DOT sub-blocks to realize the adaptive selection of embedding strength. The experimental results show that the maximum distortion error in pixel value for the extracted secret image is ±1. And the color cover image can provide good quality after embedding large amount of data.
基金Supported in part by China Postdoctoral Science Foundation under Grant No.201M550839in part by the Key Research Program of the Chinese Academy of Sciences under Grant No.KGZD-EW-603
文摘Modeling technique for electromagnetic fields excited by antennas is an important topic in computational electromagnetics, which is concerned with the numerical solution of Maxwell's equations. In this paper, a novel hybrid technique that combines method of moments(MoM) with finite-difference time-domain(FDTD) method is presented to handle the problem. This approach employed Huygen's principle to realize the hybridization of the two classical numerical algorithms. For wideband electromagnetic data, the interpolation scheme is used in the MoM based on the dyadic Green's function. On the other hand, with the help of equivalence principle, the scattered electric and magnetic fields on the Huygen's surface calculated by MoM are taken as the sources for FDTD. Therefore, the electromagnetic fields in the environment can be obtained by employing finite-difference time-domain method. Finally, numerical results show the validity of the proposed technique by analyzing two canonical samples.
