国际角度关键量值-角度块比对的方法及结果

介绍了中国计量科学研究院在2000年度CIPM组织的CCL-KC3国际角度关键量值比对项目中的角度块比对中所采取的测量方法、测量结果及不确定度分析,并提供了CIPM发布的各参比实验室的角度块比对数据,供国内角度计量领域的同行进行参考.我国的4个角度块的比对数据比较接近平均值,同时加权值En均小于1,说明我国提供的角度块的测量不确定度结果是合理的.     

角度块示值误差测量审核及En值的应用

申请实验室用示值误差优于2″的测量角仪对角度块的示值A1进行测量,分析测量过程中测量重复性、光学瞄准、仪器误差等影响,得到示值误差的测量不确定度U1(k=2);参考实验室用多齿轮分度台对角度块的示值A2进行测量,评估测量过程的不确定度来源,得到示值误差的测量不确定度U2(k =2);用公式计算得到示值误差测量审核的En值为0.4,角度块示值误差的测量审核的结果为满意.     

二级角度块角度偏差测量结果不确定度评定

一、测量原理使用最大允许示值误差为±2″的测角仪,依据JJG70-2004《角度块》检定规程规定的方法对工作角为50°的二等角度块角度偏差进行连续测量,得到测量结果分别为-21″、-24″、-19″、-18″、-17″、-23″、-19″、-20″、-21″、-18″。取该组数据的平均值为输入测量的最佳估计值-20″,测量结果为49°59′40″。     

万能角度尺测量结果不确定度评定

本文根据角度尺的示值误差(角值偏差)由角度尺对角度块直接测量,与标准角度比较其差值而获得.从而评定出测量结果的不确定度.     

二级角度块角度偏差测量值不确定度的评定

由于测量误差的存在,再加被测量自身定义和误差修正的不完善等缘故,被测量的真值难以准确复现,测量结果带有不确定性,因此用测量不确定度来评定测量结果的质量高低。本文通过对二级角度块测量过程中的不确定度进行分析评定,找出影响不确定度的主要因素,为实验室质量控制、科学判定测试结果提供科学依据。     

万能角度尺示值误差的不确定度分析

文章依据不确定度传播定律介绍了万能角度尺的测量方法、不确定度来源及测量模型,根据万能角度尺的测量方法和测量程序分析得到影响万能角度尺示值误差结果的因素。再通过对万能角度尺进行10次重复性测量后,利用贝塞尔公式计算得到其单次实验标准差,从而计算得到A类标准不确定度,然后从角度块的资料计算得到万能角度尺的B类标准不确定度,最后经过合成得到万能角度尺的合成标准标不确定度,取置信因子k=2进而得到其扩展不确定度。     

1级、2级角度块工作角角值偏差测得值的不确定度评定

本文介绍了角度块的测量原理,针对精密测角仪测量装置校准1级角度块和2级角度块的时候,工作角角值偏差测得值的不确定度分析,验证了校准测量能力,旨在为从事相关工作的技术人员提供参考依据。     

角度块的修理

角度块在使用一段时间后,会出现不同程度磨损.(1)工作面粗糙度降低、工作面出现锈蚀、平面度超差.(2)工作面与非工作面垂直度超差.(3)工作角(角值)磨损超差.这些现象出现,直接影响角度测量准确度,因此必须对其进行修理.     

用万能工具显微镜测量角度块的方法及误差分析

本介绍在没有测角时借助万工显测量角度的方法，根据测量误差的理论分析和实测表明，该测量方法可满足二级角度块的测量准确度。     

非整度数角度块工作角偏差测量结果的不确定度评定

介绍了利用两台不同型号的多齿分度台,叠放在一起,配以自准直仪对非整度数角度块工作角偏差的测量方法,分析了不确定度来源,并对测量不确定度进行了评定.     

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.     

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.     

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.     

可燃气体检测报警器测量结果的不确定度评定

本文详细介绍了可燃气体检测报警器示值误差测量结果的不确定度评定方法。     

水三相点复现的不确定度评定

水三相点是开尔文热力学温度的唯一基准点，也是ITS-90国际温标重要的定义固定点。因此，水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来，中国计量科学研究院研制出一系列高质量的水三相点容器，加强了水三相点的研究，为不确定度的分析提供了更为可靠的实验依据。同时，不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此，根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明，其扩展不确定度为0．16mK(k=2．69，P=0．99)。     

心电图机电压测量示值误差测量值的不确定度评定

本文介绍了心电图机电压测量示值误差测量值的不确定度评定与表示方法。     

Estimation of potentialities of methods of summation of direct measurement errors

Conventional methods for summation of direct measurement errors are considered. Conditions under which these methods provide consistent results are stated. It is proposed to utilize for characteristic of the total error, its interval estimator or the half-sum of the value obtained by adding up its arithmetic and geometric random errors.Translated from Izmeritel'naya Tekhnika, No. 4, pp. 10–12, April, 1995.