基于奇异值分解的鲁棒零水印算法

针对当今数字水印技术中透明性不好、鲁棒性差、内容完整性差等问题,提出基于小波包分解和奇异值分解相结合的零水印算法,该算法利用小波包对高频信息进一步分解和奇异值分解的稳定性好,健壮性特点和数字水印隐秘性强的优势,和零水印相结合,解决鲁棒性差,内容不完整等的问题.首先,充分了解小波变换的原理,在此基础上对小波包分解和奇异值分解充分研究,然后把载体图像进行置乱、奇异值分解和提取特征矩阵;生成零水印最后,将零水印保存至版权保护中心,在后期认证中用于鉴定版权所有.小波包分解克服了小波变换不能分解低频的缺点,奇异值分解在图像分解过程中具有很好的稳定性从而提高了水印的鲁棒性.零水印不需要把水印信息嵌入载体中,进而保证了内容的完整性,仿真实验表明,零水印算法具有较好综合性能,与同类零水印算法相比,鲁棒性稳步提升,所容纳的数据信息更多,并实现了更方便的认证.     

基于DT-CWT和SVD的鲁棒音频水印算法

在音频检索中为了利用音频水印进行信息标注,以及有效地权衡音频水印的嵌入容量、透明性和鲁棒性之间的关系,提出了一种基于双树复小波变换(DT-CWT)和奇异值分解(SVD)的鲁棒音频水印算法.首先提取原始语音的音频指纹作为音频水印;然后通过基于能量的嵌入位置选择来确定水印嵌入帧,进行4级DT-CWT后选取高频分量分段进行SVD;最后通过量化的方法在奇异值矩阵的奇异值中嵌入水印信息.实验结果表明:该算法具有较强的鲁棒性和透明性,并具有较高的嵌入容量,可以很好地满足信息标注的需要.     

基于二元树复小波和SVD不变性的纹理图像分类算法

针对双树复小波变换(DT-CWT)用于图像的纹理特征提取时,不具有旋转和尺度不变性的局限,提出了一种基于DT-CWT和SVD的纹理分类算法.该算法首先利用DT-CWT从图像中提取出纹理特征,然后对纹理特征进行奇异值分解获得具有旋转和尺度不变性的特征向量,采用BP神经网络作为分类器,并提出改进的BP算法训练网络,使得网络很快找到全局最优解.将本方法与其他的分类算法进行比较,实验结果表明,本算法具有较高的分类正确率.     

基于SVD变换的立体图像零水印算法

深度信息是立体图像最重要的特征,而常见的鲁棒性数字水印算法可能使立体图像深度信息遭到破坏而使其视觉效果下降.针对这个问题,提出了一种基于SVD变换的零水印算法.首先,对立体图像的左右视点图像块分别进行SVD变换,得到第一奇异值对应的左奇异向量;其次,分别计算出左右视点图像块的左奇异向量的方差;最后,利用第一奇异值对应的左奇异变量具有很好的稳定性这一特性,通过比较二者大小关系构造出零水印.同时,引入了时间戳机制,减弱了解释攻击带来的影响.仿真实验结果证明,此算法能够避免零水印的虚警概率,同时能够抵抗JPEG压缩攻击和高斯攻击,具有很好的均衡性、相似性和鲁棒性.     

基于小波系数重要值与SVD的零水印算法

为提高水印算法的抗攻击性能,提出了一种基于小波系数重要值与奇异值分解(SVD)的零水印算法.算法对宿主图像的低频子带进行分块,在密钥的控制下,伪随机地选择低频子带中的两块共4个系数组成一组,找出每组中的重要值;对重要值进行分块奇异值分解,最后通过判断每个子块最大奇异值的最高位数字奇偶性产生零水印.实验结果表明,该算法在抵抗普通攻击与抗旋转几何攻击方面均具有较好的鲁棒性.     

基于Curvelet-DWT-SVD的零水印算法

针对传统零水印算法在不同强度攻击下的鲁棒性和稳定性差等问题,利用Curvelet变换和奇异值分解的稳定、高效和近乎最优的表示性能,提出一种基于Curvelet-DWT-SVD的零水印算法。首先,将载体图像分成互不重叠的子块;其次,每一子块进行Arnold置乱和Curvelet变换得到各个子块的粗尺度层Curvelet系数;然后,将Curvelet系数进行小波变换得到细尺度的小波系数,并将其分块处理;同时对各个子块进行奇异值分解,并根据各个子块的最大奇异值构造特征矩阵;最后,将预处理后的版权水印与特征矩阵进行异或操作生成零水印。实验结果表明,该算法对于噪声攻击、压缩攻击、滤波攻击和剪切攻击等具有很好的鲁棒性,是一种可靠、鲁棒性强的零水印算法。     

一类基于SVD的数字水印虚警分析与改进算法

讨论一类基于奇异值分解(SVD)的水印算法的高虚警率问题及其产生原因。分析认为SVD水印算法虚警率高的根本原因是:图像SVD分解的基空间与图像内容相关;奇异值向量与图像之间并不存在一一对应关系,不能刻画图像的几何结构。算法主要缺陷并不是出现在提取算法,而是嵌入算法仅仅植入了水印图像的奇异值向量,没有水印图像在基空间的结构信息。因此,该文提出了一个基于分块SVD和离散余弦变换(DCT)分解的改进算法。该算法通过在版权图像的奇异值向量中嵌入水印图像的DCT系数,克服了经典SVD水印算法的虚警问题,因而稳健性高。实验验证了理论分析和算法的有效性。     

天波雷达短驻留时间下海杂波抑制的改进算法

在高频天波雷达的舰船目标检测中,为消除电离层变化带来的谱展宽效应,采用了短驻留时间下基于奇异值分解(SVD)的海杂波抑制算法.该算法对构造出的Hankel矩阵进行奇异值分解,将对应于海杂波分量的奇异值置零,再重新构造出数据序列,达到海杂波抑制的目的.相对于原有的迭代杂波对消算法,该算法无需估计众多参数及设置对消截止门限,并且可以获得更好的抑制效果.为了有效地识别分解后的海杂波与目标所对应的奇异值以避免错误对消,还提出了一种改进方案,可以在抑制前分辨出海杂波分量和目标所对应的奇异值,当回波目标的能量与海波处于相近量级以及多目标情况下,能够避免错误对消现象的出现.仿真结果验证了所提算法的有效性.     

基于DWT-SVD和Turbo码的彩色图像盲水印算法

为进一步提高数字水印系统的性能, 提出一种离散小波变换域中基于奇异值分解和Turbo纠错码的彩色图像盲水印算法. 首先对数字水印进行混沌加密预处理, 然后进行Turbo编码, 再把编码后的水印信息嵌入到彩色图像蓝色分量小波分解后低频子带的奇异值矩阵中. 提取水印时不需原始载体图像的参与, 更便于实际应用. 仿真实验结果表明, 该水印算法不可见性较好, 且对常见攻击和几何攻击具有较好的稳健性.     

基于SVD算法的无线光MIMO系统的性能分析

介绍了无线光多输入多输出(OMIMO:Wireless Optical Multiple-input Multiple-output)通信系统的基本组成,针对系统中存在背景光噪声和多址干扰对系统的影响,分别采用了基于奇异值分解(SVD)算法和迫零(ZF)检测算法来消除多址干扰,用Matlab进行了仿真,并对两种算法的仿真结果做了比较.仿真结果表明:在通信质量要求不高、信道矩阵奇异的情况下,采用SVD算法可以有效地消除多址干扰,很好地逼近ZF算法性能.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

正~~