超声导波信号形态分量分析方法研究

超声导波无损检测技术由于其传播距离远、检测范围大等优良性能,被广泛应用于航空航天、油气管道、压力容器等领域的检测.由于沿波导的长距离传播,超声导波除了有一般体波的特点外,还具有频散和多模态特性,该特性极大地限制了超声导波的检测效果,增大了特征识别的困难.开展针对超声导波频散和多模态特性的研究具有重要的理论和现实意义.本文通过分析超声导波频散和多模态特性的特点,提出从导波信号处理角度出发,采用形态分量分析的信号处理技术,深入研究导波信号的形态分解问题,并通过实验信号对方法的有效性进行了验证,为解决频散和多模态的影响以及为复杂导波信号的分析提供关键技术.     

钢板内应力激光超声导波检测方法研究

为了在钢板生产过程中实现钢板内应力的在线非接触无损检测,研究了基于激光超声导波的钢板内应力检测方法。搭建了激光超声导波应力测试装置,开发了相应的信号采集、处理及分析软件,组建了激光超声应力检测实验研究平台。通过拉伸加载装置,给实验试样两端施加预先计算的拉伸载荷,实现了所需要的各种工况下的钢板内应力场。通过激光超声检测单元采集各种载荷下的激光超声导波信号,实验研究了激光超声导波对钢板内应力的表征能力与关联规律。实验结果表明,脉冲激光可以在硅钢板中激发出以A0模态为主的宽频激光超声导波;激光超声导波相速度随拉力的增大而增大,群速度随拉力的增大而减小;拉应力与激光超声导波信号的首波超前时间差和波包延迟时间差都存在明显的线性关系。激光超声导波检测方法可用于带钢内应力的非接触无损检测,有可能成为钢板带内应力在线检测的新方法。     

基于导波技术的小口径管网实时检测系统

基于超声导波无损检测技术,发展了一种用于小口径管网实时检测的新型诊断系统。系统包括以压电陶瓷晶片为敏感器件的柔性传感器阵列,导波激励接收硬件子系统及分析软件。柔性传感器阵列能表面贴装于任意尺寸的管线外壁,并可在管线中激励和接收轴对称模态导波。与现有导波激励接收系统不同,诊断系统包含有多通道的信号转换开关矩阵,能实现管网中不同管线检测所需信号通道的快速自动切换。检测实验表明,分析软件能有效辨识大于3%管线横断面积的腐蚀损伤,并能实时检测管线的状态变化,如腐蚀损伤扩展等。诊断系统具有检测效率高,使用灵活的特点,为小口径管网的实时检测提供了有效手段。     

基于ICS1702的超声导波检测系统电源管理设计

电源部分是超声导波检测系统的关键组成部分,良好的电源管理系统是保证检测系统正常工作的基础。为适应野外检测条件,实现检测系统的小型化、便携化,文中以电源管理芯片ICS1702为核心,提出了一种用于超声导波检测系统的电源管理设计方法,并设计了相关的硬件和软件部分。实验证明该电路具有控制简单,成本低的优点,实现了电源的小型化,为超声导波检测仪的便携式提供了可能。     

基于超声导波波谱法管道缺陷检测仿真研究

针对超声导波检测难以准确判定管道缺陷的问题,通过分析超声导波遇管道缺陷后其回波的传播,提出了以波谱法来定位和定量管道缺陷。采用ANSYS软件仿真了T(0, 1)模态超声导波在带缺陷管道中的传播,得到检测的幅值波谱图,发现波谱图中缺陷处的颜色总是最先变化;通过分析所有节点同一时间坐标信号的幅值,发现相对最大缺陷信号幅值,幅值衰减在1/10内的节点数与缺陷的周向尺寸之间存在确定的系数关系。     

基于模态分离算法的管道焊缝缺陷周向定位研究

针对管道焊缝质量的检测问题,研究了一种基于超声导波的管道环焊缝缺陷周向定位方法,可快速确定管道焊缝中的缺陷周向位置。该方法基于超声导波模态分离算法,分离出焊缝回波信号中的对称、非对称模态,提取对称、非对称模态峰值,并利用非对称模态与焊缝中非对称缺陷的对应关系,确定缺陷所在周向位置。通过试验验证了该方法的正确性,并总结出可检测缺陷的范围。     

超声导波管道诊断仪系统主机的实现

本系统主机主要有三个功能:首先,产生一脉冲激励源,其中心频率、周期数、幅值、重复频率等参数均可设置以适用于超声导波信号特征,并进行信号处理、功率放大,从而驱动负载产生超声导波,以实现对被检测管道的激励;其次,实现对传感器输出的信号调理、数据采集、数据保存及数据传输;最后,实现其它辅助功能。本文详细阐述了超声导波脉冲激励源及多通道高速数据采集的实现。     

基于DS89C430的超声导波激励信号源的设计

为减少管道超声导波检测中频散现象给检测工作带来的不利影响,提出了一种针对管道的超声导波激励信号源的设计方法,采用超高速单片机DS89C430、数模转换器件AD9708和运算放大器LM318等器件,设计出专门用于激励超声导波的汉宁窗调制单音频信号的窄带信号发生器,该信号发生器可实现汉宁窗的宽度可调,汉宁窗调制下的单音频信号频率可调的功能.实验结果表明设计合理,激励信号中单音频的频率及汉宁窗调制单音频的周期数调节方便.     

基于导波能量差的管道缺陷周向定位实验研究

针对超声导波检测需通过对回波信号进行分析而得到管道健康信息,而无法反映缺陷的周向位置信息的问题。文中采用超声导波方法对管道缺陷周向定位进行了研究,分析了超声导波在管道中遇缺陷后的能量分布,以及周向定位的原理。根据F(1,3)模态导波周向波数只有一个的特性,提出了象限能量差定位缺陷方法,并对该方法进行了实验研究,结果表明,方法可以准确地判定出缺陷所在周向位置。     

基于超声导波的水下管道缺陷检测

文中介绍一套可拆式传感器系统设计与制作,利用超声导波原理对水下管道的腐蚀进行检测,基于厚度剪切模式的压电陶瓷和可拆式固定装置组成,可拆式传感器系统包括传感器PZT特别设计,并且可以把传感器装置夹在要检测的管道上。当对水下设备的管道进行了一系列的测试,结果表明传感器系统能够有效地激发和接收T（0,1）模式的超声导波,由于T（0,1）模式超声导波能够在水下管道上长距离传播,因此适用于缺陷检测。人为缺口的回波信号与缺口的尺寸以及位置具有良好的相关性。研究表明这一可拆式传感器系统能够利用导波有效地对水下管道进行检测。     

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.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

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.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

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.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

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.     

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.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.