超长导轨直线度对激光测长示值的影响北大核心CSCD

应用空间解析几何方法,从理论上对由于超长导轨直线度引起的角锥棱镜空间位置变动而最终导致的激光光程的变化进行了分析,并据此建立了相应的数学模型;结合实际测量中使用的超大量程激光测长机导轨直线度的实际测量数据分析了直线度对激光测长示值的实际影响,得出符合阿贝原则的测长机在26 m内由导轨直线度误差引起的激光测长误差小于0.1 μm的结论。     

长导轨直线度分段测量拼接方法研究

激光干涉仪测量超长导轨直线度时,因导轨长度超出干涉仪直线度测量范围,需分段测量后拼接,测量数据易受噪声和激光漂移等因素影响,导致拼接可能引入较大误差。通过分析拼接过程中的影响因素,结合长导轨结构特性,提出了一种将拼接公共点分布在相邻两节子导轨上,利用相邻两节子导轨夹角的稳定特性来实现长导轨直线度拼接的方法。通过仿真与实验,对比了30m范围内的直接测量法与坐标变换拼接法的测量结果,2种方法的直线度结果相差＜10μm,表明所提出的方法能有效减小拼接误差。将此方法应用于72m导轨的直线度测量,并与电子水平仪测量方法比较,2种方法结果相差10μm,表明所提出的方法可实现高精度的直线度拼接。     

一种超大量程激光万能测长机及其测量不确定度分析北大核心CSCD

为进一步提高激光测长机的测量范围、测量精度及可靠性,满足装备制造产业等向大型化、高精度和可互换性方向迅速发展中对超长尺寸的计量要求,研制了一台超大量程激光万能测长机。采用花岗岩导轨做基座,激光干涉仪为标尺,设计符合阿贝原则的测轴,由气浮滑块支撑,并应用温度实时补偿技术,提高准确度和长期稳定性。对影响激光测长机测量准确度的误差进行了不确定度分析。实验结果表明,该激光测长机的测量范围达 26 m ,测量准确度达到0.3 μm+0.2×10 -6 L,k =2。     

基于PSD的分离式长导轨直线度测量方法研究

利用分段拼接测量方法能够将PSD激光准直测量系统测量范围扩大,相较于传统长导轨直线度测量方法,该方法可同时适用于连续型导轨和分离式超长导轨的直线度测量。首先,在(-5～+5) mm测量范围内,通过激光干涉仪分别测得激光准直测量系统的接收靶在水平和竖直方向上的位移,误差均优于±(1μm+1%H)。然后,在40 m范围内与激光准直测量系统的直线度测量精度进行对比,二者水平方向直线度误差相差0.06 mm,竖直方向直线度误差相差0.13 mm。最后,在70 m分离式超长导轨上,测得水平方向直线度为0.50 mm,竖直方向直线度为0.53 mm。该方法可迅速定位和调整直线度误差极值点位置,能够较为有效地解决分离式超长导轨的直线度装配调试问题。     

基于激光干涉仪同步测量的动态校准装置

为满足时变几何量的瞬时动态测试需求,研制了一种基于激光干涉仪同步测量的动态校准装置。该装置采用直线运动导轨和运动发生器、长度标准器激光干涉仪,以基于GNSS驯服时钟的同步触发器实现同步测量并确保时间准确稳定,并使用动态校准软件实现控制一体化。经综合分析激光干涉仪的最大允许误差、直线运动导轨的直线度、环境因素、触发信号间时延及激光干涉仪测量时延等因素,该装置的长度示值的测量不确定度为Q[1.8μm, 3×10^-7L](k=2)。与同型号激光干涉仪的比对实验和激光跟踪仪瞬时长度测试实验,证明了不确定度评定的合理性以及该装置在瞬时动态准确度测试中的可行性。     

动态测量光栅测长仪的位置误差

介绍了一种光栅测量系统动态位置精度评定的方法,以现有的光栅测长仪为研究对象,高精度HP5529A双频激光干涉仪作为校准系统.利用光栅测长仪编码器产生的A-quad-B脉冲信号触发激光干涉仪进行同步动态数据采集,由激光干涉仪软件来获取和显示位置误差数据,并绘制更真实详细的动态误差图.最后对动态误差实验结果进行分析和讨论.     

大尺寸测量

大尺寸如何利用高端精密设备进行精密测量,文章介绍方法是在原有的测长机上架上双频激光形成了激光测长机,更有效地提高了测量精度。     

用5528A双频激光测量系统测量长导轨直线度数据连接的精度分析

根据我院造船系的要求,我们对某船池导轨进行了直线度测量,导轨全长160m。本文对测量数据连接的精度作一分析介绍。一、确定测量方案根据要求,我们决定选用HP-5528A双频激光测量系统对其进行测量。我们现有的测量直线度误差附件仅能测量3m内的直线度。如果用它来测量160m长导轨,其工作量是很大的,因此我们采用一套可测量25m长的测角附件,对其分段测量,然后进行数据连接,最后得到全长的直线度误差值。具体测量方法是: 对全长为160m的船池导轨进行分段测量,桥板跨距为400mm,各段均测21.2m,各段间重叠测点愈多,计算精度愈高,而工作量也相应增加,但至少得重叠两个测点,我们根据     

基于LabVIEW的内径千分尺检定系统软件设计

正在保证检定数据准确可靠的前提下,为了快速完成检定工作并处理数据,笔者设计了基于LabVIEW的内径千分尺检定系统。一、总体设计根据激光干涉仪的工作和安装方式,测长机配合测量内径千分尺的示值误差有两种读数方法:第一种是测长机的分米读数用激光干涉仪读数,毫米及微米读数直接在测长机上读取,三部分读数之和作为内径千分尺的实际尺寸;第二种是测长机的分米和毫米读数用激光干涉仪读数,微米读数直接在     

测长机与测长仪差异及其发展趋势研究

本文阐述了测长仪与测长机在工作原理和装置结构上的差异,研究由此而产生的两者在测量准确度以及实际校准工作中校准方法上的区别。在此基础上,介绍了现代测量长度仪器所采用的双频激光技术、微电子技术,展望测长机与测长仪中的发展趋势。     

Estimation of Parameters of Universal Distribution of Moments of Failure of Products

A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling.     

Assessment of intakes of mixtures of radionuclides

Australia has several uranium mines and a large number of mineral sand mines, with associated processing facilities. Exposures resulting from these mining and processing operations usually involve intakes of mixtures of radionuclides. This work describes the development of a suite of first order, linear compartment models, based on the ICRP Publication 66 respiratory tract model, and an analytical solution to the decay equations, for assessing the consequences of such intakes. The computer programs based on these models directly compute excretion, organ retention and organ and whole-body doses for intakes of either single radionuclides or any mixture of radionuclides belonging to the same radioactive decay chain. The intake can be via inhalation, ingestion or injection, and can be acute, chronic or of limited duration. The starting concentration and degree of secular (dis)equilibrium can be specified for each radionuclide. No assumptions need to be made about the relative magnitudes of the radioactive half-lives of the different nuclides.     

卧式金属罐容量的测量结果不确定度

本文根据多年的实践检定经验 ,参照JJF1 0 59- 1 999《测量不确定度评定与表示》以及《测量不确定度表达 1 0讲》 ,对卧式金属罐容量的测量结果不确定度进行了评定。     

盐酸浓度不确定度的评估

通过对盐酸浓度标定的过程分析，找出影响结果的各个分量，进行不确定度的评定，按照计量技术规范给出标准的表示法。     

Evaluation of optical properties of highly scattering media by moments of distributions of times of flight of photons

A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue.     

Analysis of anisotropy of properties on the basis of studies of texture of coarse-grained ingots of thermoelectric materials

An analysis of anisotropy of the properties of a Bi₂Se_0.3Te_2.7 solid solution was carried out using construction of demonstrative surfaces for thermoelectric effectiveness and thermal expansion coefficients. It is shown that the texture is an important factor forming anisotropy of properties and technological fitness of ingots for manufacturing modules. Anisotropy of properties based on the studies of the ingot textures obtained using the float-zone method and Bridgman method (growing thermoelectric plates in a flat cavity) was studied.     

Analysis of the rate of propagation of the wave of change of boiling modes

An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate agreement is demonstrated between the derived relations and experimental data.