激光导波阵列波束成形损伤成像方法

激光超声检测方法在结构损伤检测领域有着广泛应 用。增加激光信号用于损伤成像的技术难点。针对此挑战,采用提出的Morlet小波分析法提 取激光宽频信号中对应中心频率下的窄带信息。为实现损伤 的可视化,分析比较了导波阵列波束成形损伤成像算法中时间延迟叠加算法和相位延迟叠加 算法,其中相位延迟叠加成像法对频域内所有频率成分实施延迟叠加能克服导波的频散效应 得影响,能实现对损伤更精确的定位。为验证该方法的实用性,构建了激光激励/接收完全 非接触式的实验系统,通过对Morlet小波分析后的信号采用延迟叠加算法对损伤进行成像, 实验结果表明了:相位延迟叠加成像法成像效果比时间延迟成像法成像效果更佳,定位更精 确。     

CS损伤成像中的时间逆转多重信号分类算法

将时间逆转多重信号分类算法应用于混凝土结构内部损伤检测中,由换能器单元发射的信号和接收的损伤回波信号构建传递矩阵,并通过对传递矩阵奇异值分解后得到的奇异值反映了损伤的数量与损伤的程度,奇异向量则包含了损伤信息,基于多重信号分类算法结合奇异向量对CS内部结构成像并实现损伤定位,通过数值仿真和实验验证了时间逆转成像方法用于CS损伤检测的可行性,实现了损伤的准确定位。     

基于概率成像的二维波束聚焦冲击定位方法研究

冲击损伤监测是结构健康监测的主要研究内容之一.本文提出了一种基于十字型传感器布置方法的二维波束聚焦概率成像定位算法,采用十字阵列型的传感器布置方法减小了系统盲区,通过二维波束聚焦概率成像方法提高了冲击定位的精度.在二维波束聚焦算法中,波速的准确性是影响结构冲击损伤定位的主要因素,本文通过统计分析得到波速的概率分布函数,带入二维波束聚焦概率成像定位算法中对冲击损伤进行监测,分别得到横向阵列与纵向阵列的概率分布图,对两者进行融合成像可以得到更为精确、科学且直观的冲击损伤定位结果.通过实验研究验证了该方法的有效性与实用性.     

基于关联维数的超声Lamb波损伤成像

研究了混沌分形理论的一种特征参数——关联维数的定义计算及参数选择。提出了一种基于关联维数的板状复合材料超声兰姆(Lamb)波损伤检测方法。通过计算采集健康与无损信号的关联维数,对比其数据差异,作为一种损伤指标,用于概率成像算法的损伤位置定位成像。利用有限元分析进行模拟实验研究,结果表明,提出的算法能准确对复合材料脱层缺陷进行定位成像。     

基于反卷积神经网络的超声导波层合板脱粘缺陷超分辨成像

针对传统超声导波成像检测方法难以精确表征结构损伤细节特征的问题，文中提出了基于深度学习的反卷积神经网络模型，对层合板中亚波长脱粘缺陷的超分辨成像问题进行研究，以获得损伤的细节特征。通过有限元仿真与全聚焦成像算法获取初始成像结果，再使用数据增强方法扩充数据库，最后对标注好的12 550张损伤图像进行训练和测试。研究结果表明，与原始全聚焦成像算法相比，反卷积神经网络模型下损伤的成像位置准确度提高了5%,成像精度高于91%,定位误差低于1.8 mm,说明文中所提方法能够明显提高网络成像结果分辨率并较好地显现亚波长损伤的细节特征。上述结果表明文中所提方法具有较高的检测效率，且无需人工经验，在工程实践中具有良好的应用价值。     

热固性/热塑性复合材料分层损伤红外热波检测能力评估

主动红外热成像技术在不同基体复合材料分层损伤中的检测能力尚未被评估.文中通过设计制作两种典型热固性/热塑性复合材料层压板,分别采用脉冲红外热成像、超声红外热成像、超声C扫描三种方法对不同冲击能量下的分层损伤进行了检测研究.以超声C扫描结果为参照,对比了两种红外热成像技术的检测结果,同时针对热图序列损伤区域的阈值分割提取开发了基于图像强度值相似性理论的区域生长算法.损伤的定量识别结果表明:脉冲热成像对热固性复合材料的分层损伤检测效果较好,但其不适用于热塑性复合材料损伤检测,超声热成像对于两类复合材料分层损伤均有较好的检测能力且整体检测精度优于脉冲热成像.期间对不同损伤检测效果的深层次机理进行了分析,并提出了分别针对两种基体类型复合材料的红外热成像技术评估流程和标准.     

基于压电阵列的无波速主动损伤监测方法研究

主动技术在结构健康监测研究中有着不可替代的作用。文章研究了基于压电传感阵列的无波速主动结构健康监测方法,给出了单像素点的损伤概率计算方法及在不计算Lamb波波速的情况下对结构进行主动损伤成像、定位的方法。通过实验,对比了利用波速标定值的传统方法和无波速监测方法的成像定位效果,发现了无波速主动监测方法能有效提高定位精度,提升成像效果,为基于压电阵列的结构健康监测技术提供了一种新的工业应用方法。     

低温压力容器的无损视觉检测方法研究

为了提高对低温压力容器实验设备的损伤检测能力,提出一种基于高速主动红外视觉成像分析的低温压力容器的无损视觉检测方法。首先对低温压力容器的破损、磨损、裂缝等部位进行红外热成像的三维视觉重建,然后采用多层次纹理映射方法进行损伤特征点提取和检测,将低温压力容器实验设备损伤特征点输入到特征映射关系模型中,结合热激励源的差异性视觉状态特征实现低温压力容器实验设备损伤的视觉重建,最后进行仿真测试。结果表明,采用该方法进行低温压力容器的无损视觉检测的准确性较高,对损伤点的定位精度较好。     

毫米波辐射计对金属目标的探测

针对金属目标的探测问题,依据金属的毫米波辐射特性,提出一种基于毫米波辐射计成像的金属目标探测方法。该方法首先利用毫米波辐射计扫描目标并成像,再用区域标记算法标记成像图像,通过分析标记区域的面积排除干扰信息,最后检测出金属目标。实验表明,该方法能够从各种背景中有效检测出金属目标,为下一步目标的识别、跟踪与定位提供了依据。     

基于传递矩阵修正的近场MUSIC算法研究

针对MUSIC谱估计算法在近场声源定位成像中出现的边沿放大问题,提出了一种阵列传递矩阵修正方法,该方法不考虑近场声压幅值衰减效应.实现了近场条件下的MUSIC算法声源定位成像的应用,并通过仿真与直接波束形成算法、去自谱波束形成算法进行了对比研究,检验了该算法的性能.仿真实验证明采用修正阵列传递矩阵后的MUSIC算法可以实现近场声源定位成像,可作为较近距离和较低频率条件下一种补充定位成像算法.     

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.