利用SURF和PLSA的遥感图像场景分类

针对遥感图像场景分类的特点,提出了一种基于SURF和PLSA的分类方法。该方法首先采用SURF算法提取图像的局部特征,其次对特征利用K-means聚类生成视觉词汇表,从而得到图像的视觉词袋描述。然后利用概率潜在语义分析(PLSA)从图像中提取潜在语义特征,最后使用支持向量机(SVM)分类器完成图像的场景分类任务。在21类场景图像上的实验结果表明,文中方法可以有效提高遥感图像的场景分类精确度。     

生成模型与判别方法相融合的图像分类方法

本文通过在图像局部特征基础上基于高斯混合模型建立全局视觉词汇,用局部特征相对于不同视觉单词的后验概率之和所形成的特征向量来描述图像,最终利用基于线性核的支持向量机进行图像分类.实验中比较了与其它同类方法在PASCAL VOC 2006图像集上的分类结果,验证了本文提出的分类方法及其与目标区域（前景）特征相结合在提高分类效果上的有效性.     

多方向上下文特征结合空间金字塔模型的场景分类

针对场景分类问题中,传统的“词包”模型不包含图像的上下文信息,且没有考虑图像特征间的类别差异问题,本文提出一种多方向上下文特征结合空间金字塔模型的场景分类方法。该方法首先对图像进行均匀网格分块并提取尺度不变（SIFT）特征,对每个局部图像块分别结合其周围三个方向的空间相邻区域,形成三种上下文特征;然后,将每类训练图像的上下文特征分别聚类形成视觉词汇,再将其连接形成最终的视觉词汇表,得到图像的视觉词汇直方图;最后,结合空间金字塔匹配算法形成金字塔直方图,并采用SVM分类器来进行分类。该方法将图像块在特征域的相似性同空间域的上下文关系有机地结合起来并加以类别区分,从而形成了具有更好区分力的视觉词汇表。在通用场景图像库上的实验表明,相比传统方法具有更好的分类性能。      

基于近义词自适应软分配和卡方模型的图像目标分类方法

传统的视觉词典模型（Bag of Visual Words Model,BoVWM）中广泛存在视觉单词同义性和歧义性问题.且视觉词典中的一些噪声单词-“视觉停用词”,也会降低视觉词典的语义分辨能力.针对这些问题,本文提出了基于近义词自适应软分配和卡方模型的图像目标分类方法.首先,该方法利用概率潜在语义分析模型（Probabilistic Latent Semantic Analysis,PLSA）分析图像中视觉单词的语义共生概率,挖掘图像隐藏的语义主题,进而得到语义主题在某一视觉单词上的概率分布;其次,引入K-L散度度量视觉单词间的语义相关性,获取语义相关的近义词;然后,结合自适应软分配策略实现SIFT特征点与若干语义相关的近义词之间的软映射;最后,利用卡方模型滤除“视觉停用词”,重构视觉词汇分布直方图,并采用SVM分类器完成目标分类.实验结果表明,新方法能够有效克服视觉单词同义性和歧义性问题带来的不利影响,增强视觉词典的语义分辨能力,较好地改善了目标分类性能.     

复杂场景下结合SIFT与核稀疏表示的交通目标分类识别

针对复杂场景下的交通目标分类识别难点,提出一种基于尺度不变特征转换(SIFT)与核稀疏表示的分类识别算法.该算法首先利用SIFT分别提取训练样本和待测目标局部特征信息,通过核方法将特征样本映射到核空间,构建过完备字典,最后通过待测目标在字典中的稀疏度与重构误差对交通目标类别进行判定.同时,分析了随机投影下的核稀疏表示分类与特征维数之间的关系.实验结果表明,与SVM、稀疏表示分类(SRC)相比,该方法增强了交通目标特征层的类判别能力,具有较好的识别率和鲁棒性.     

基于BOW模型的相似图像分类检索方法

传统的相似图像检索大多基于颜色、纹理、场景等特征,缺少对图像的局部特征提取,忽视了局部特征对相似图像检索的影响,检索效果较差。本文采用视觉BOW(Bag of words)模型,提取图像中尺度不变的SIFT特征,形成视觉单词向量,设计了一个基于视觉单词的相似图像分类检索方法,取得了较好的分类检索效果。     

基于概率图模型目标建模的视觉跟踪算法

提出了一种视觉跟踪任务中基于局部特征和概率图模型的目标建模方法,将目标表示为一组具有仿射不变性的区域特征,并通过概率图模型描述特征之间的空间约束关系。在目标跟踪过程中,首先在空域上利用信任传播算法,推断概率图模型中各个特征的状态,然后根据推断的结果设计改进的重要性采样函数,采用粒子滤波算法在时间域上对目标进行跟踪。为了适应目标在运动中的变化,模型根据特征的稳定程度自适应地进行更新。实验结果表明,该方法具有较强的鲁棒性,能够有效实现复杂场景下的目标跟踪。     

一种基于上下文语义信息的图像块视觉单词生成算法

基于视觉单词的词包模型表示(Bag-of-Words)算法是目前场景分类中的主流方法.传统的视觉单词是通过无监督聚类图像块的特征向量得到的.针对传统视觉单词生成算法中没有考虑任何语义信息的缺点,本论文提出一种基于上下文语义信息的图像块视觉单词生成算法：首先,本文中使用的上下文语义信息是视觉单词之间的语义共生概率,它是由概率潜在语义分析模型(probabilistic Latent Semantic Analysis)自动分析得到,无需任何人工标注.其次,我们引入Markov随机场理论中类别标记的伪似然度近似的策略,将图像块在特征域的相似性同空间域的上下文语义共生关系有机地结合起来,从而更准确地为图像块定义视觉单词.最后统计视觉单词的出现频率作为图像的场景表示,利用支持向量机分类器完成图像的场景分类任务.实验结果表明,本算法能有效地提高视觉单词的语义准确性,并在此基础上改善场景分类的性能.     

面向自然场景分类的贝叶斯网络局部语义建模方法

本文提出了一种基于贝叶斯网络的局部语义建模方法.网络结构涵盖了区域邻域的方向特性和区域语义之间的邻接关系.基于这种局部语义模型,建立了场景图像的语义表述,实现自然场景分类.通过对已标注集的图像样本集的学习训练,获得贝叶斯刚络的参数.对于待分类的图像,利用该模型融合区域的特征及其邻接区域的信息,推理得到区域的语义概率;并通过网络迭代收敛得到整幅图像的区域语义标记和语义概率;最后在此基础上形成图像的全局描述,实现场景分类.该方法利用了场景内部对象之间的上下文关系,弥补了仅利用底层特征进行局部语义建模的不足.通过在六类自然场景图像数据集上的实验表明,本文所提的局部语义建模和图像描述方法是有效的.     

一种基于自适应软分配的图像分类方法

视觉词袋模型(BoVW)是当前图像分类领域的主流方法,然而,视觉单词同义性和歧义性问题严重制约了该模型的性能,进而降低图像分类准确率。针对该问题,本文提出一种基于自适应软分配的图像分类方法。该方法首先对尺度不变特征变换(SIFT)特征映射到视觉单词的距离进行分析,按一定的规则进行归类,并针对具有不同模糊程度的SIFT特征采用自适应的分配策略;然后,通过卡方模型分析各个视觉单词与图像类别之间的相关性,并依此去除视觉停用词(VSW),重构视觉单词统计直方图;最后,输入到支持向量机(SVM)完成分类。实验结果表明,该优化方法能有效地降低视觉单词同义性和歧义性问题带来的影响,增强视觉单词的区分性,进而提高图像分类准确率。     

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.     

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.     

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.     

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.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

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.