基于随机蕨的集成分类图像隐写分析算法

提出了一种基于随机蕨(random ferns)和集成学习的图像隐写分析算法。首先利 用图像高维特征构 建蕨特征,采用成对采样策略构造样本子集,生成若干个基分类器;然后计算出训练样本 在基分类器中各个蕨的 先验概率并集成各个基分类器,进行隐写检测判别。实验结果表明,本文算法复杂度低,能 有效降低隐写检测错误率。     

基于特征排名的图像隐写分析算法

为提高用于隐写分析的集成分类器的检测精度,提出一种基于特征排名的隐写分析算法。首先计算每维检测特征的互信息得分并根据得分高低将特征进行排名,然后设置分界点将特征分为重要特征区域与普通特征区域,依据设定的抽样比例从两个区域随机抽取特征组成不同的特征子空间并训练集成分类器。最后使用集成分类器进行分类。实验结果表明,针对使用nsF5及S-UNIWARD算法进行隐写的频域及空域图像,本算法较传统分类器在检测错误率方面分别平均下降约0.006 5和0.006 2,具有较好的检测效果。针对频域与空域中两种不同的隐写算法,与传统的集成分类器相比,该算法具有更高的检测精度。     

基于贝叶斯分类器的图像隐写分析

集成分类器是目前用于图像隐写分析的主流分类器。为提高集成分类器的检测精度,针对集成分类器基分类器组合方法过于简单,无法体现基分类器之间的内在联系,不能从整体上对结果进行判定的缺点,依据图像特征在集成分类器分类超平面上的投影值服从多维正态分布这一特性,提出了一种基于贝叶斯分类器的图像隐写分析算法。首先基于随机森林算法生成若干基分类器,然后计算类条件概率密度函数与先验概率并训练贝叶斯分类器,最后使用经过训练的贝叶斯分类器代替简单投票方法进行分类判决。算法的检测错误率比以往算法平均降低了1.6%,ROC曲线比简单投票方法更接近于左上角,即具有更高的检测率,AUC值平均增长约2.12%,并且训练时间仅有少量提高,最大提高约2.610s。可以有效提高集成分类器的检测精度。     

基于帧间共谋的视频隐写分析

基于视频序列的时域特性,提出一种应用帧间共谋策略的视频隐写分析算法.分析了视频序列中所含局部运动对隐写分析检测精度的干扰,将秘密信息和局部运动建模为双模噪声,据此提出基于视频帧间分块相关度的特征提取策略.隐写分析算法依据提取的特征应用GRNN分类器进行视频帧的分类,以识别含秘密信息的可疑视频帧,在一定程度上降低了局部运动的影响.实验结果表明该算法可实际应用于视频隐写分析.     

基于改进局部纹理特征的隐写检测算法

图像隐写是一种将信息隐藏于数字图像中的技术,而隐写检测算法试图分辨出藏有信息的图像。文中分析了现有隐写检测算法的优势,结合HUGO隐写算法的特点,提出了一种改进的基于局部纹理特征的隐写检测算法。该算法由LOCP和LPQ这两种局部纹理特征组成。由于提取到的特征维度很大,因此选用了Ensemble分类器进行训练与检测。在HUGOBOSS 1.0图像库上的实验显示,提出的隐写检测算法比原有算法更准确地区分出原始图像和隐写图像,并获得了83.65%的检测准确率。     

失真代价动态更新的自适应彩色图像隐写算法

基于灰度图像隐写算法直接应用于彩色图像引起的安全性问题,该文针对彩色分量提出一种动态更新失真代价的空域隐写算法。首先,分析了彩色分量内容特性与通道间相关性的关系,提出中心元素的失真更新准则。随后,考虑到隐写过程中邻域分量嵌入修改产生的交互影响,得到维持邻域相关性的最优修改方式。最后,提出彩色分量的失真代价动态更新策略(CCMS),并应用该策略设计实现了一种彩色图像的空域自适应隐写算法。实验表明,在5种嵌入率下HILL-CCMS,WOW-CCMS算法对彩色隐写特征CRM,SCCRM的抗检测能力明显高于HILL和WOW算法。     

基于DCT域最低位平面量子位的隐写分析

针对Jsteg、MB、OutGuess三种JPEG图像隐写算法,提出了一种基于DCT域最低位平面量子位的隐写分析算法。该算法通过分析JPEG图像隐写前后子块DCT域最低位平面量子位叠加系数的变化,提取该量子位16个叠加系数作为特征向量,之后用LSSVM分类器对待测图像进行分类,最终达到检测载密图像的目的。实验表明,该算法能有效地对JPEG图像进行隐写分析,同时对低嵌入比例下的栽密图像也能达到较高的检测率。     

基于颜色梯度特性的彩色图像隐写分析

基于彩色图像任意2个颜色通道间梯度方向随机序列及颜色梯度和随机序列的振荡特性在隐写前后均有明显变化的特征,提出了一种基于颜色梯度特性的彩色图像盲隐写分析算法。算法应用HHT(Hilbert-Huang transform)提取4个序列在隐写前后的内在振荡特征差异,构建基于Hilbert谱的特征向量,采用SVM分类器进行分类判别。实验表明,该算法误检率低,检测性能优于现有彩色图像隐写分析算法,可以实现彩色图像隐写的可靠检测。     

基于不确定性推理的JPEG图像通用隐藏信息检测技术

目前隐写分析通常被作为一种确定性问题进行研究,研究中忽略了不确定性因素的影响,这导致了检测可靠性下降.本文对通用隐写分析中的不确定性因素进行了分析.在此基础上,构建了基于不确定性推理的隐写分析模型,设计了基于证据推理的通用隐写分析算法.实验证明了算法具有较好的可扩展性和可靠性,从而也验证了使用不确定性推理方法解决隐写分析问题的有效性.     

一种基于权重融合的JPEG隐写分析方法

针对JPEG图像通用隐写检测中检测效率低、训练时间长的问题,提出一种基于集成分类器的新检测方法。算法以CC-PEV为特征对图像进行描述并作为隐写分析特征;然后,随机构造若干个特征子空间,用bootstrap方法构造图像训练子集,分别进行训练得到数个基分类器;根据基分类器的分类结果赋予基分类器不同的权重,将基分类器的结果按照其权重进行融合得到最终的结果。本文对该算法进行了测试,对它的集成性、检测准确率和训练时间进行分析。实验结果表明,相对于传统的集成方法,本文方法用自举方法构造训练集、随机方法构造子特征空间、赋予基分类器不同权重进行融合能够显著地提高算法准确率。本文方法相对于SVM和传统的集成分类方法,具有更高的检测率,对于特征维数更大的图像检测,具有更好的拓展性和一般适用性。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.