信号处理在超声检测中的应用

文章综合报道了信号处理在超声检测的抑噪、缺陷的定性定量分析及优化驱动信号的几方面应用。     

超声显微检测方法对产氚包层焊缝的适用性研究

针对产氚包层中盖板流道封焊的结构设计与特点,开展了超声显微检测方法研究,确定了超声显微检测参数及该方法的适用性问题。以盖板流道封焊为研究对象,选择JSR DPR500 超声显微检测系统进行检测参数研究,分析了超声显微检测中探头参数及声束聚焦的特点;采用不同参数探头及水层厚度,提高了检测灵敏度,并解决了盖板流道封焊中小缺陷不易检出的难题。     

显微成像光谱仪技术的研究及应用

显微成像光谱仪技术是一种生物组织检测方法,目前广泛应用于生物医学检测和疑难病症分析,已成为组织检测领域的研究热点。论述了显微成像光谱仪各结构功能模块的工作原理及特点,并对其各主要技术指标进行了分析。介绍了目前的发展现状,并对所出现的多种显微成像光谱仪的技术方案及特点做了详细的总结。研究结果表明,显微成像光谱技术作为一种新的技术手段,必将在临床医学、生物学、材料学以及分析化学等领域得到广泛的应用。     

激光超声无损检测技术及其在岩体物性测试中的应用

激光超声无损检测技术是材料无损检测的一种重要手段,是目前人们所关注的一种重要的检测方法.文章阐述了激光超声的激发原理和激光超声信号检测方法,详细介绍其在对岩体物性测试中的应用,并且针对目前存在的一些技术难题指出了今后的解决方向.     

遗传算法在超声检测反演参数中的应用

本文简单介绍了遗传算法的理论基础和计算流程,讨论它的优越性能。结合反常 纤维样品独立弹性常数的实验,探讨了遗传算法在此领域中的应用,与前反演结果相比较,验证了该算法的有效性。     

深度学习在超声检测缺陷识别中的应用与发展*

深度学习（Deep Learning）是目前最强大的机器学习算法之一,其中卷积神经网络（Convolutional Neural Network, CNN）模型具有自动学习特征的能力,在图像处理领域较其他深度学习模型有较大的性能优势。本文先简述了深度学习的发展史,然后综述了深度学习在超声检测缺陷识别中的应用与发展,从早期浅层神经网络到现在深度学习的应用现状,并借鉴医学影像识别和射线图像识别领域的方法,分析了卷积神经网络对超声图像缺陷识别的适用性。最后,探讨归纳了目前在超声检测图像识别中使用CNN存在的一些问题,及其主要应对策略的研究方向。     

插值数字滤波技术在超声检测仪中的应用

本文主要研究用最优化技术来设计符合超声脉冲信号幅度精度要求的数字滤波器，从而提高了超声检测的质量。     

超声在固体火箭发动机无损检测中的应用

在固体火箭发动机的研制中，无损检测技术非常重要。本文介绍了一些主要的超声检测方法及其应用。脉冲多次反射法用于检测固体火箭发动机壳体与衬层之间的粘结质量。特性参数和扫频超声法以多层介质理论为基础，用于检测固体火箭发动机的深层粘结质量。     

96-全国检测超声技术研讨会

由中国声学学会检测声学分会超声专业委员会和超声成像专业委员会，与中国机械工程学会无损检测分会超声专业委员会和促进NDT仪器器材发展委员会联合召开的“96一全国检测超声技术研讨会”于1996年6月8日至10日在江苏省宜兴市召开。中国声学学会检测声学分会主任委员李明轩研究员和中国机械工程学会无损检测分会副主任委员蒋危平研究员共同主持了这次会议。会议得到武汉科声公司和宜兴科声公司的大力支持并具体承办。宜兴市钱副布长和省电子厅的同志到会。出席会议代表40余人，集中了我国从事超声无损检测技术和检测超声学研究的一些科研…     

虚拟仪器技术及其在超声测量中的应用

虚拟仪器是电子技术,测量技术和计算机技术共同发展的产物。本文介绍了虚拟仪器的基本概念、虚拟仪器的一般结构,虚拟仪器的优点和特点。文中还了作者应用虚拟仪器思想在超声测量上所做的工作一岩土工程质量检测分析仪,最后探讨了它的应用前景。     

扫描镜的研制工艺与检测

用于卫星探测等仪器中的扫描镜，形状一般为三面或四面镜，技术要求很高，因此，加工工具和方法也需要相应的改进。粗加工时主要控制面与面的角度和对称尺寸；精抛时即要注意面形，又要控制面与面的角度与塔差。加工过程中检查面形主要用平面干涉仪，检查面间夹角和塔差使用两个光轴互相垂直的平面仪，加工结果，四反射面扫描镜最佳面间夹角误差优于１″，塔差和平行度以及面形均达到技术要求。     

Non-invasive and low-artifact in vivo brain imaging by using a scanning acoustic-photoacoustic dual mode microscopy

Photoacoustic imaging is a potential candidate for in vivo brain imaging, whereas, its imaging performance could be degraded by inhomogeneous multi-layered media, consisted of scalp and skull. In this work, we propose a low-artifact photoacoustic microscopy (LAPAM) scheme, which combines conventional acoustic-resolution photoacoustic microscopy with scanning acoustic microscopy to suppress the reflection artifacts induced by multi-layers. Based on similar propagation characteristics of photoacoustic signals and ultrasonic echoes, the ultrasonic echoes can be employed as the filters to suppress the reflection artifacts to obtain low-artifact photoacoustic images. Phantom experiment is used to validate the effectiveness of this method. Furthermore, LAPAM is applied for in-vivo imaging mouse brain without removing the scalp and the skull. Experimental results show that the proposed method successfully achieves the low-artifact brain image, which demonstrates the practical applicability of LAPAM. This work might improve the photoacoustic imaging quality in many biomedical applications which involve tissues with complex acoustic properties, such as brain imaging through scalp and skull.     

Local thermal conductivity of polycrystalline AlN ceramics measured by scanning thermal microscopy and complementary scanning electron microscopy techniques

The local thermal conductivity of polycrystalline aluminum nitride (AlN) ceramics is measured and imaged by using a scanning thermal microscope (SThM) and complementary scanning electron microscope (SEM) based techniques at room temperature. The quantitative thermal conductivity for the AlN sample is gained by using a SThM with a spatial resolution of sub-micrometer scale through using the 3ω method. A thermal conductivity of 308 W/m·K within grains corresponding to that of high-purity single crystal AlN is obtained. The slight differences in thermal conduction between the adjacent grains are found to result from crystallographic misorientations, as demonstrated in the electron backscattered diffraction. A much lower thermal conductivity at the grain boundary is due to impurities and defects enriched in these sites, as indicated by energy dispersive X-ray spectroscopy.     

Calculation of scanning tunnelling microscopy images for Kr/graphite system

The scanning-tunnelling-microscopy (STM) images of Kr atoms adsorbed on a monolayer graphite sheet (Kr/graphite system) are calculated using the first-principle total-energy electronic structure calculations within the density functional theory in the local density approximation. The results obtained agree well with the observations. It is found that the optimal site of the adsorbed Kr atom is at the top of the centre of the carbon hexagon, and its equilibrium distance from monolayer graphite surface is about 0.335nm. It is shown that the hybridization of C 2p electronic states (π-electronic states) and Kr 4p and 5s electronic states is the main origin of the Fermi-level local density of state.     

Dopant profiling in silicon nanowires measured by scanning capacitance microscopy

Silicon nanowires (SiNWs) with axial doping junctions were synthesized via the Au‐catalyzed vapor–liquid–solid growth method with the use of HCl. In this work, dopant profiling from three axially doped SiNWs with p–i, p–n and n–i–p junctions were investigated using both scanning electron microscopy (SEM) and scanning capacitance microscopy (SCM). It turns out that observed doping contrasts in SEM are also affected by the surface roughness and sample charging. In contrast, SCM allows us to delineate with sub‐10 nm resolution the electrical junctions and provides a relative value of the doping concentration in each segment of the NW. SCM clearly evidences the expected doping regions within these SiNWs thanks to the addition of HCl during the growth that strongly prevents shell overgrowth. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Application of spatially and temporally apodized non-confocal acoustic transmission microscopy to imaging of directly bonded wafers

Application of a line-shaped point spread function (PSF) to imaging of void defects in directly bonded wafers is considered. Two non-confocally adjusted spherical transducers are employed to implement an acoustic microscope operating in transmission with a time dependent point spread function, whose shape is optimized by both temporal apodization of the received signal and spatial apodization of the transducer aperture. Strong imaging artifacts resulting from the generation and detection of edge waves are eliminated in this way. It is shown by several examples that only a broadband system can be utilized in order to obtain a line-shaped PSF suitable for imaging.     

Local thermal conductivity of polycrystalline AlN ceramics measured by scanning thermal microscopy and complementary scanning electron microscopy techniques

The local thermal conductivity of polycrystalline aluminum nitride (AlN) ceramics is measured and imaged by using a scanning thermal microscope (SThM) and complementary scanning electron microscope (SEM) based techniques at room temperature.The quantitative thermal conductivity for the AlN sample is gained by using a SThM with a spatial resolution of sub-micrometer scale through using the 3ω method.A thermal conductivity of 308 W/m·K within grains corresponding to that of high-purity single crystal AlN is obtained.The slight differences in thermal conduction between the adjacent grains are found to result from crystallographic misorientations,as demonstrated in the electron backscattered diffraction.A much lower thermal conductivity at the grain boundary is due to impurities and defects enriched in these sites,as indicated by energy dispersive X-ray spectroscopy.     

结构光照明超分辨光学显微成像技术与展望

结构光照明显微镜(Structured Illumination Microscopy,SIM)通过结构化照明在频率域以空间混频的方式将物体高频信息载入光学系统的探测通带内实现突破衍射极限的超分辨光学显微成像。SIM凭借其较低的激发光强、对荧光染料的非特异性需求以及快速的宽场成像优势已成为活细胞超分辨光学显微成像方面应用最多的技术。本文系统回顾了SIM的技术进展,对SIM的基本原理与实现方法进了详细的分析,重点介绍了本课题组研发的基于光谱分辨的单光子激发超分辨显微镜和结合自适应光学的双光子激发超分辨显微镜这两种最新的SIM技术,最后简要讨论了SIM技术在生物成像中的应用及未来发展方向。     

Distance resolution of the scanning acoustic air microscope

In this paper the experimental results concerning the distance resolution measurements performed with the air microscope operating with a focussing transducer at 1.27 MHz are presented. A distance resolution of 3 nm has been achieved, corresponding to the average distance between two molecules in air at normal conditions. The influence of air temperature variations on the distance measurements has been taken into account.     

光子扫描隧道显微镜的光电成像系统研究

本文论述了光子扫描隧道显微镜（ＰＳＴＭ）的显微成像机理、成像规律，针对具体的物理模型进行数值模拟计算，并得到了与实际探测相一致的场分布规律。采用自行研制的光子扫描隧道显微镜（ＰＳＴＭ）的显微实验系统对多种样品进行了表面显微成像研究，获得了关于样品表面三维立体图像信息，通过多种图像处理手段对原始图像进行后期处理，得到了更具视觉效果、更为逼真的样品表面图像。