可活化稳定同位素^70Zn示踪研究儿童膳食中锌的生物利用率

使用中子活化分析法,以国内仅有的低深缩度^70Zn（18．3％）作为可活化稳定浓缩同位素示踪剂,对我国儿童膳食中锌的生物利用率进行了研究。建立了以阴离子树脂交换法对儿童便样中的锌元素进行富集,经反应堆中了辐照、测量和放射化学分离、测定锌的生物利率方法。提出了普适于各种^70Zn浓缩度锌作为示踪剂、以^70Zn和^68Zn和^64Zn的质量丰度进行生物利率率的计算公式。克服了以^68Zn作为唯一的天然锌指示而引入的计算误差。     

激光加载下准等熵压缩实验用铝/氟化锂复合双台阶靶的研制

本文提出了一种激光加载下准等熵压缩实验用铝/氟化锂复合双台阶靶的加工技术。采用金刚石车削在1.5 mm厚的氟化锂晶体表面加工两个10 μm高度的台阶,然后利用电子束蒸发在氟化锂台阶面镀厚度为几十μm的高致密纯铝膜,再通过金刚石车削工艺将镀铝面车削成平面,最后在氟化锂晶体另一面蒸镀剩余反射率低于1%的增透膜,最终获得高质量的铝/氟化锂复合双台阶靶。采用NT1100白光干涉仪、电子比重计、电子能谱、X射线衍射仪、扫描电镜等设备对靶参数进行测量,研究各工艺对靶参数的影响。     

红旗轿车三维分离流动特性

介绍了使用激光片光技术及激光多普勒测速仪对红旗ＣＡ７７４ 轿车尾流的三维分离流的尾迹和速度分布测定的试验研究。研究表明,光学流态显示和数字图象技术相结合,可以有效地揭示汽车的尾流结构,诊断阻力来源。本项研究为建立汽车三维分离流动的动态仿真理论模型提供了依据。     

激光焊接技术在粉末冶金材料中的应用

系统地介绍了激光焊接技术在粉末冶金材料中的应用及其国内外动态。着重介绍了激光焊接在金刚石工具制造业中的应用和尚存在的问题     

Electric-field induced fluctuations in laser generated plasma plume

The effect of an external electric field on laser-generated plasma has been studied. It is observed that the laser-generated plasma can be used for the ignition of a spark in the presence of a low voltage external electric field. An eight-fold emission intensity enhancement in Cu Ⅰ spectral lines are measured as compared to the signal intensity in the absence of an external electric field.The plasma parameters remain the same initially, up to a few microseconds after the generation of plasma, and this feature makes it more interesting for the quantitative analysis of any sample using laser induced breakdown spectroscopy(LIBS). In the presence of an external electric field,fluctuations(contraction and expansion) in the laser-generated plasma are observed which increase the plasma decay time and consequently result in enhanced signal intensity.     

基于线阵CCD的新型微位移传感器的研究

常用的激光三角法微位移传感器适用于直线位移测量,不适用于微小角位移的动态测量.因此研制了一种新型的基于线阵CCD的微小角位移传感器,采用平行光斜射式激光三角法,由准直透镜、聚焦透镜及光栏等光学器件、高速线阵CCD及由CPLD、信号发生电路和采样保持电路等构成的实时信号处理电路组成,具有结构简单,线性度好,灵敏度高,测量频率高,分辨率高和实时性好等特点;介绍了其结构和工作原理,实验测试其特性,并将其应用于高频电-机械转换器动态特性的测量.研究表明该传感器的最大量程为0.2rad,分辨率为0.0002rad,最高测量频率为10 kHz,可应用于高频电-机械转换器等元件的微小角位移的特性的动态检测.     

Enhancement of optical emission generated from femtosecond double-pulse laser-induced glass plasma at different sample temperatures in air

In double-pulse laser-induced breakdown spectroscopy(DP-LIBS), the collinear femtosecond double-pulse laser configuration is experimentally investigated with different initial sample temperatures using a Ti:sapphire laser. The glass sample is ablated to produce the plasma spectroscopy. During the experiment, the detected spectral lines include two Na(I) lines(589.0 nm and 589.6 nm) and one Ca(I) line at the wavelength of 585.7 nm. The emission lines are measured at room temperature(22 ℃) and three higher initial sample temperatures(T_s?=?100 ℃, 200 ℃, and 250 ℃). The inter-pulse delay time ranges from-250 ps to 250 ps.The inter-pulse delay time and the sample temperature strongly influence the spectral intensity,and the spectral intensity can be significantly enhanced by increasing the sample temperature and selecting the optimized inter-pulse time. For the same inter-pulse time of 0 ps(single-pulse LIBS), the enhancement ratio is approximately 2.5 at T_s?=?200 ℃ compared with that obtained at T_s?=?22 ℃. For the same inter-pulse time of 150 ps, the enhancement ratio can be up to 4 at T_s?=?200 ℃ compared with that obtained at T_s?=?22 ℃. The combined enhancement effects of the different initial sample temperatures and the double-pulse configuration in femtosecond LIBS are much stronger than that of the different initial sample temperatures or the double-pulse configuration only.     

基于机器视觉的镭射膜跑偏检测

针对镭射膜纵切过程中的跑偏问题,提出一种基于机器视觉的检测方法。用CCD摄像机采集具有几何特征的镭射膜图像,对预处理后的图像采用改进Canny算法边缘检测并创建ROI区域,利用Hough变换得到特征直线,调用相关算法并计算出镭射膜跑偏角度。实验结果表明,改进Canny算法能够检测到较为完整的边缘细节,具备较强的自适应性,Hough变换对镭射膜的特征提取效果良好,为计算跑偏角度提供了较为准确的依据。     

Uniformity of gallium doped zinc oxide thin film prepared by pulsed laser deposition

Recently, transparent conducting oxide thin films have attracted attention for the application to transparent conducting electrodes. In this work, we evaluated the uniformity of electrical, optical and structural properties for gallium doped zinc oxide thin films prepared on the 10 × 10 cm² silica glass substrate by pulsed laser deposition. The resistivity, carrier concentration, mobility, bonding state and atomic composition of the film were uniform along in-plane and depth direction over the 10 × 10 cm² area of the substrate. The film showed the average transmittance of 81-87%, resistivity of 1.4 × 10^− 3 Ω cm, carrier concentration of 9.7 × 10²⁰/cm³ and mobility of 5 cm²/Vs in spite of the amorphous X-ray diffraction pattern. The gradual thickness distribution was found, however, the potential for large-area and low temperature deposition of transparent conducting oxide thin film using pulsed laser deposition method was confirmed.     

Application of High-Speed Laser Polarimetry to Noncontact Detection of Phase Transformations in Metals and Alloys at High Temperatures

A high-speed laser polarimetry technique, developed recently for the measurement of normal spectral emissivity of materials at high temperatures, was used to detect solid–solid and solid–liquid phase transformations in metals and alloys in millisecond-resolution pulse-heating experiments. Experiments were performed where normal spectral emissivity at 633 nm was measured simultaneously with surface radiance temperature, resistance, and/or voltage drop across the specimen. It was observed that a phase transformation, as indicated either by an arrest in the specimen radiance temperature or changes in the resistance and/or voltage drop, generally caused a change in normal spectral emissivity. Experiments were conducted on cobalt, iron, hafnium, titanium, and zirconium to detect solid–solid phase transformations. Similar experiments were also performed on niobium, titanium, and the alloy 85titanium–15molybdenum (mass%) to detect solid–liquid phase transformations (melting).