基于SIDWT的多模态脑部医学影像融合算法北大核心

研究了人脑CT/MRI医学图像融合算法。传统的基于小波变换的融合方法由于不具备平移不变性,在融合图像的奇异处易产生失真。提出了一种基于平移不变离散小波变换(SIDWT)的新融合方案。利用SIDWT将待融合的医学图像分解成低频子带和高频子带。对于高频子带,提出平滑度来划分子带区域,针对不同区域采用不同的融合规则,更好地保持了源图像的边缘细节信息。对于低频子带,采用基于局部区域对比度的融合规则。实验结果表明,该算法融合性能优越,比传统的融合算法获得更好的融合效果。     

基于小波方向相关性的图像融合方法

通过分析图像经小波变换后低频系数的邻域相关性和各高频子带的区域方向性,本文提出一种基于小波方向相关性的图像融合方法.对低频子带的每个系数,以多向梯度模作为其自相关性的衡量标准,确定融合后低频系数;对于各个高频子带的系数,根据其不同的方向特性,采用基于方向相关系数的融合规则.最后通过对比仿真实验,验证本文方法的有效性.     

基于NSST的红外与可见光图像融合算法

针对红外与可见光图像具有不同的特点,提出一种新的基于非下采样剪切波变换（NSST）的红外与可见光图像融合算法.算法首先采用NSST将已配准的红外与可见光图像进行分解,得到低频子带图像和各尺度各方向的高频子带图像;然后对低频子带图像采用一种基于显著图的低频融合规则进行融合,而对高频子带图像的融合,结合人眼视觉特性,采用一种基于改进的区域对比度的融合规则;最后,对融合的低频子带图像和高频子带图像进行NSST逆变换得到融合图像.实验结果表明,该算法能够有效地综合红外与可见光图像中的重要信息,融合效果要优于一般的基于NSCT、NSST的图像融合方法.     

基于多尺度几何分析的医学图像融合

针对医学图像,提出了一种基于多尺度几何分析的医学图像融合算法。首先,利用Contoutlet变换对待融合两幅图像进行分解,将得到的低频分量分别利用Shearlet变换分解,并采用区域能量加权平均的规则,进行一次融合得到融合低频分量;对得到的高频分量分别用小波变换进行分解,再用低频、高频取大的规则进行一次融合得到融合高频分量,最后对得到的融合高低频分量进行Contourlet逆变换得到融合结果。实验结果表明,该算法在信息熵和平均梯度等参数上有明显提升,且能更好地表征图像中不同的奇异性。     

双色红外图像融合在目标检测中的应用

针对双色红外的图像融合特点,提出了一种基于在小波分解域中,在高频子带上采用区域能量测度融合规则,在低频子带上采用加权平均融合规则。首先,双色红外成像系统分别对中波和长波红外图像进行提升小波分解,提取出2幅图像的低频和高频信息,并采用不同的融合规则对低频和高频子带图像进行融合,然后通过提升小波反变化对各层系数进行重构,得到目标区域的融合图像。而后再通过小波软阈值化去噪,最后进行目标自动检测。通过实验对比证明,提出的融合规则更好地提高了目标的检测和识别概率。     

基于图像信息的红外与可见光图像融合方法研究

研究了红外图像与可见光图像的融合问题,提出了一种基于图像信息的图像融合新算法.首先利用非采样Contourlet变换的多分辨率特性和平移不变性对图像进行多尺度和多方向分解,得到一系列子带图像,然后针对图像变换后各带通方向子带高频系数的特点,提出了度量图像信息的融合规则.图像的低频部分决定了图像的轮廓,对低频子带应用简单...     

shearlet变换和区域特性相结合的图像融合

为了提高多模医学图像或多聚焦图像的融合性能,结合shearlet变换能够捕捉图像细节信息的性质,提出了一种基于shearlet变换的图像融合算法。首先,用shearlet变换将已精确配准的两幅原始图像分解,得到低频子带系数和不同尺度不同方向的高频子带系数。低频子带系数使用改进的加权融合算法,用平均梯度来计算加权参量,以此来改善融合图像轮廓模糊度高的问题,高频子带系数采用区域方差和区域能量相结合的融合规则,以得到丰富的细节信息。最后,进行shearlet逆变换得到融合图像。结果表明,此算法在主观视觉效果和客观评价指标上优于其它融合算法。     

基于非子采样Contourlet变换的图像融合算法

提出了一种基于非子采样Contourlet变换的图像融合算法.首先,对图像作Contourlet变换,得到一个低频子带和一系列高频方向子带.其次,对低频子带系数采用基于边缘的规则来融合,而对于高频方向子带系数,采用基于一种基于Contonrlet局部系数相关性的规则来进行融合.最后,对融合系数进行非子采样Contourlet逆变换,得到最终的融合图像.实验结果表明,该方法对可见光、红外图像融合十分有效,能较好地提取原始图像中的边缘方向信息和几何特征.     

一种多传感器图像融合与数字水印技术

在小波包域提出了一种多传感器图像融合和双水印算法。首先,利用HIS变换和小波包变换将多光谱和全色图像分解为多个高低频子带,根据小波包域系数特点,低频部分采用基于区域平均能量加权算法的规则进行融合,高频部分采用绝对值取大的规则进行融合。然后,在高低频图像融合系数分别嵌入一个水印,低频水印利用了离散余弦变换的聚能去相关能力,高频水印利用了图像纹理子块特征。最后,对嵌入的双水印融合图像进行攻击和分析。实验结果显示,融合图像在保留多光谱图像光谱信息的基础上有效提高了空间分辨率;加水印的融合图像具有良好的不可视性和鲁棒性。     

基于Contourlet的改进梯度多聚焦图像融合

针对传统图像融合保留源图像信息和边缘信息的不足,提出了一种基于轮廓波的改进梯度图像融合算法。首先源图像经轮廓波分解,得到低频和高频子带系数;其次,低频采用改进梯度、高频采用SML的选取规则;最后轮廓波反变换得到融合图像。实验表明,本文提出算法比小波方法、传统轮廓波方法融合效果好。融合图像的信息量大,边缘信息丰富。     

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.