针对小波域量化隐藏方法的图像监测技术研究

基于对图像小波变化后各子带系数的不同统计特性，提出了一种针对小波域信息隐藏算法的新型图像隐写术分析技术。通过对原始图像和隐藏信息后的图像的小波变换系数子带直方图的分析，得出了小波域信息隐藏对子带系数的改变特性。进一步对系数进行傅立叶变换，从而量化信息隐藏对系数的影响程度。实验结果表明该方法适用于小波域量化隐藏信息算法的检测。     

基于特征函数和高阶统计量的图像信息隐藏盲检测方法

本文对Farid的盲检测算法作了改进,提出了一种更为有效的图片信息隐藏盲检测方法.该方法引入特征函数来描述图片的统计规则性,并将图片小波子带系数及其线性预测误差的特征函数的高阶统计量作为图片的特征向量来建立分类模型.实验结果表明,该方法能有效检测出含隐藏信息的图片.     

一种基于混沌和小波变换的大容量音频信息隐藏算法

 音频信息隐藏的主要原理是利用人耳听觉系统的某些特性,将秘密信息隐藏到普通的音频数据流中以达到隐蔽通信的目的.提出了一种基于混沌和小波变换的大容量音频隐藏算法.该算法首先利用混沌序列良好的伪随机特性对秘密信息进行置乱加密预处理;然后利用人耳对音频的采样倒置并不敏感,可以通过倒置的方法改变载体信息小波系数正负极性的特点,将加密后的秘密信息通过一对一地变更小波域高低频部分对应位正负极性的方法隐藏到载体信息中.实验结果表明,该算法不仅具有良好的不可感知性和鲁棒性,能够抵御噪声攻击、重采样攻击、重量化攻击以及MP3压缩攻击等,而且信息隐藏容量大,可实现盲检测.     

一种基于JPEG2000的小波域信息隐藏算法

针对JPEG2000基本压缩编码的特点,提出了一种应用于隐蔽通信的基于小波域统计特征的隐写算法.该算法首先利用置乱变换对待隐藏图像进行变换处理,并对载体图像进行多分辨率小波分解,然后根据人类视觉系统的掩蔽特性选择重要小波系数,将隐秘信息分别嵌入到重要小波系数的不同频率域中.实验结果表明,算法提高了信息隐藏的容量,较好地...     

小波域分存和软判决恢复的隐藏技术

研究了一种把小波变换和可视密码技术相结合的信息隐藏方案,实现对灰度图像的信息隐藏。该方案把经过Arnold变换处理后的秘密信息,按照k阶线性方程求解理论产生n幅分享图片,再把n幅分享图片应用离散小波变换信息隐藏理论,分存到n幅公开图片中。提取秘密图片时,必须要大于k幅公开图片才能获得秘密图片。实验结果表明,该方案具有很强的鲁棒性,而且秘密信息不容易丢失。     

基于均值量化的小波域自同步数字音频水印算法研究

文中提出了一种基于均值量化的小波域自同步数字音频水印算法。该算法是一种盲水印算法,水印提取不需要原始音频信号的参与。算法设计中运用了均值量化的策略,音频信号小波分解后,在低频系数中隐藏水印信息;引入了同步信号的思想,利用同步信号定位水印隐藏位置。实验表明,该算法具有较强的鲁棒性、抗攻击性、抗裁剪性。     

基于超混沌序列的信息隐藏算法

利用混沌对初值敏感性和小波变换多分辨率特性,提出了一种新的安全性信息隐藏方法。该算法首先利用Lyapunov指数大的4阶Chebyshev混沌映射及具有复杂相空间结构的耦合映像格子(CML)来构造安全的超混沌序列密码流,然后利用此超混沌序列将秘密信息嵌入到图像的小波域,最后进行逆小波变换生成隐秘图像。算法提取秘密信息时不需要原始图像。实验结果表明,该隐藏算法具有很好的透明性、鲁棒性和强的安全性。     

基于可视密码术的小波域音频数字水印研究

提出的基于可视密码术的小波域量化系数音频数字水印方案,采用可视密码术的方法,通过特定算法将秘密信息隐藏到一定数量的图片中,这些图片作为水印嵌入到数字作品中,恢复者可以通过将特定数量的图片叠加在一起,通过人的视觉系统就能识别恢复出原来的秘密信息,无需大量的计算和密码学的知识,所以可以为更多的人使用。     

一种基于多重统计量分析的稳健语音信息隐藏算法

本文提出了一种基于多重统计量分析的小波域语音信息隐藏算法.该算法首先将载体语音信号分成若干包含相同采样点的帧,利用短时能量以及过零率找出属于浊音段的帧分别进行多尺度离散小波分解,提取小波分解后的低频系数;然后对低频系数进行分组并计算各组系数的能量、绝对值方差等统计量的值,根据各组统计值的比较及嵌入的秘密信息比特值,采用不改变或者适当调节各组统计值大小关系的方法来隐藏信息.该算法只在语音的浊音段嵌入信息,充分考虑了人耳的听觉特性.实验结果表明:算法可以盲检测,对加噪、低通滤波、重采样、重量化等攻击均具有良好的稳健性.     

一种新的数字水印分存算法

提出了一种小波域上把RS码与线形变换共享方案相结合的数字水印分存算法.该算法在进行秘密共享时使用了RS纠错码,降低了一定的误码率,同时,水印嵌入小波域上对JPEG和JPEG 2000压缩具有较强的抵抗能力.此外,在水印信息隐藏前,对原始水印进行了加密处理,具有很高的安全性.实验表明,该算法具有较好的隐藏效果,并能很好地抵抗剪切、擦除、压缩等攻击且健壮性强.     

语义校对系统中的句子语义骨架模糊匹配算法

本文给出了用句子语义骨架表示句子语义的具体方法和表示形式.在语义校对系统中建立了这种形式的知识库,每一个知识条代表描述同一个事件的不同句子的共同特征.采用模糊匹配方法计算语句的相似程度.     

A Novel Analysis of Microstrip Structures Using the Gaussian Green's Function Method

A novel closed form expression is derived for spatial Green's functions of microstrip structures by expanding the spectral Green's function into a Gaussian series. This innovative method is called the Gaussian Green's function (GGF) method due to the Gaussian form in the closed form Green's function representation. The main advantage of the GGF method lies in its precision as well as rapid convergence. To demonstrate the versatility of this method, the current distribution of a microstrip antenna is achieved via the combination of the method of moments (MoM) and GGF method. It is shown that this method can be computationally very efficient with less than 1% error compared to the numerical integration of the spectral integral. Also, the results of the GGF method have been compared to the results of the commercial full-wave software of Agilent ADS.      

利用喇曼-米方法确定激光雷达几何因子

为了快速合理地确定激光雷达几何因子反演关键参量激光雷达比,利用雷达充满区几何因子值恒为1的属性提出一个简捷的新途径,对这种方法从理论上进行了推导,并以实际雷达数据进行了验证,反演得到的几何因子在充满区没有出现单调增加或者单调减小等不合理情况。结果表明,这种方法避免了目前激光雷达比需多次取值对结果定性分析繁琐耗时的不足,是合理有效的。这将对于反演出雷达几何因子并进而获得近地面气溶胶信息具有重要参考价值。     

Generalization of the matrix inversion lemma

A generalized form of the matrix inversion lemma is shown which allows particular forms of this lemma to be derived simply. The relationships between this direct method for solving linear matrix equations, lower-diagonal-upper decomposition, and iterative methods such as point-Jacobi and Hotelling's method are established. The generalized form is used to derive a new factorization scheme and a new matrix inversion algorithm with a high degree of parallelism.     

一种适用于机械非平稳故障信号的分析方法

该文提出了一种适用于机械非平稳故障信号的特征提取方法,鉴于该类信号时域特征明显,首先利用小波包进行分解,对分解后的不同频带内的分解系数进行时域重构,分别对重构的时间序列用时域分析的方法提取对故障敏感的特征参数,通过简化特征参数,确定判别阈值,使该方法更便于现场工作人员对机器故障的识别.同时也为具有同类特征的非平稳信号提供了一种行之有效的分析方法.文中最后用某油田往复泵实测数据验证了该方法的有效性.     

Matrix methods for the study of a regulated synchronous machine

A powerful but simple matrix method for the digital computer manipulation of large sets of differential and algebraic equations is introduced to the field of power systems. The method is first illustrated with reference to the linearized equations representing a general-purpose turboalternator model. Subsequently, the form of the system equations obtained as a result of the matrix method is seen to provide a unified approach to the determination of system stability limits using Routh, Nyquist, or eigenvalue methods. The normal state space form of the system equations is also shown to facilitate control studies. A previously suggested performance criterion for an excitation system is generalized, and a systematic method for the simultaneous optimization of governor and exciter control loops is suggested. This method of optimization does not require the evaluation of system transient responses. The manner in which the normal state space form of the system equations leads naturally to the synthesis of controllers which are optimal with respect to a chosen scalar quadratic performance index is indicated. With this form of control, the structure is not defined a priori but emerges from the computational algorithm and it becomes unnecessary to specify the source or the magnitude of the stabilizing signals required to provide an improved dynamic performance. Finally, the matrix method is shown to be effective for the manipulation of the nonlinear machine equations and these are obtained in a new form which is directly amenable to digital or analog computer solution.     

Berechnungsmethoden zur Ermittlung der Schutzstrecke bei U- und Stadtbahnen

One essential component of project planning of train control system plants is the design and calculation of the protective route. At first, definitions of the most important terms are explained. There are three different calculation methods depending on the regard of the slope of the track system as well as on the train mass representable. The simplest method only considers the maximum slope before the signal and the danger point. The second method considers the slope of the track in the form of stairs. The gradient method is presented as a third method. The regard of the inclination gradient occurs here in the form of a twofold averaging. On the one hand the mean value in the form of an integral is formed via the train length. On the other hand averaging occurs in the form of an integral via the braking distance. The middle inclination value found in this way is inserted in the iterative process for the determination of the protective route.     

Emulating switch-level models of CMOS circuits

This paper presents a method for emulating switch-level models of CMOS circuits using FPGAs. In this method, logic gates are used to model switch-level circuits without any abstraction. In contrast to the abstraction methods for which transistors are grouped together to form gates, in this method, gates are grouped together to form the switch models of transistors. The method presented in this paper, unlike the abstraction methods, can emulate many important features of switch-level models, such as bi-directional signal propagation and variations in driving strength. In order to attain a better utilization of FPGA resources a mixed-mode emulation approach has been used. In this approach parts of the circuit are emulated at the switch-level while the remaining parts of the circuit are emulated at the gate-level. The experimental results show that the presented emulation-based approach could be significantly faster than existing simulation-based approaches. The analytical performance estimation shows that the speed-up grows with the circuit size and is workload dependent.     

超椭圆曲线离散对数的Weil Descent代数攻击的分析

本文首先介绍了Galbraith的Weil Descent代数攻击方法，然后对定义在GF（q^n)上的形如y^2 xy=f(x)的HCDLP能否用Weil Descent代数方法攻击作了详细讨论，作为例子，研究了GF（4）和GF（8）上的这类曲线。得到结论：（1）Weil Descent代数攻击法只能适用于极少部分这类超椭圆曲线；（2）当亏格或基域增大时，Weil Descent方法攻击成功的概率趋向于0。所以说Weil Descent代数攻击法对建立在GF（2^n)上的这类超椭圆曲线密码体制并没有太大的威胁。