钢筋抗拉强度测量结果的不确定度评定

用微机控制电液伺服式万能试验机测量钢筋的抗拉强度时,为确定测量结果的分散性即测量结果的置信区间,对影响检测结果的诸多因素进行分析,确定不确定度产生的来源,并采用A类不确定度评定和B类不确定度评定的方法,对各个不确定度分量进行评定,再根据各个量的方差和协方差算得合成标准不确定度,最终用扩展不确定表示,给出钢筋抗拉强度测量的不确定度报告。     

声校准器测量结果的不确定度评定

本文依据JJG176-2005《声校准器》检定规程,找出对声校准器测量准确性影响的不确定度因素,确定声校准器测量准确性与不确定度来源之间的关系。用适当的方法确定各不确定度来源的不确定度,根据《测量不确定度表示指南》,测量不确定度传播定律,计算出被测声校准器的测量不确定度。     

测量不确定度及其应用

测量不确定度在测量工作中非常重要并有广泛的应用。本文阐述了测量不确定度的基本概念,通过实例说明,表示测量结果的质量时,为什么要用不确定度,而不用误差;不确定度与准确度的区别等基本知识。     

一般工作用压力表示值误差不确定度评定

文章介绍了弹簧管式一般压力表测量示值误差不确定度评定的步骤与方法,并给出了测量不确定度报告与校准测量能力.     

测量结果不确定度评定技巧

测量结果的不确定度评定应用越来越广泛了,在校准与测量完成后,均需给出测量结果的不确定度。但很多时候,测量结果不确定度保持不变,究其原因,虽然大家明白每次都应重新计算,但因计算繁琐,计算数据太多太烦。基于此,在此介绍一种简单可行的测量结果不确定度评定技巧,可迅速解决此问题。     

测量不确定度的科学评定及相关概念浅析

本对测量不确定度及误差等相关概念进行简单的分析讨论,主要对测量不确定度评定方法中的B类不确定度评定的基本方法进行了阐述。     

导体直流电阻测量结果的不确定度分析

本文依据国家标准提供的检测方法,对被测电线样品进行了测量,分析了测量过程各因素对测量结果的影响情况,提供了测量结果不确定度的评定过程,并对标准不确定度、合成不确定度、扩展不确定度以及测量结果的表示给予了明确的论述。     

公法线千分尺示值误差测量结果的不确定度评定

文章采用JJF1130-2005<几何量测量设备校准中的不确定度评定指南>中的方法对公法线千分尺示值误差测量结果的不确定度进行评定.给出了目标不确定度,并根据不确定度误差的来源对测量结果进行分析计算,得到合成标准不确定度.通过对目标不确定度和合成标准不确定度的大小比较来得到最终判据.     

测量不确定度基本原理和评定方法及在材料检测中的评定实例 第五讲 测量不确定度的评定方法(扩展不确定度的评定、报告及表示)

正5.5扩展不确定度的确定扩展不确定度是被测量可能值包含区间的半宽度。也就是说扩展不确定度是确定测量结果区间的量,合理赋予被测量之值分布的大部分可望包含于此区间。扩展不确定度有时也称为展伸不确定度或范围不确定度,或总不确定度。扩展不确定度分为U和Up两种。在给出测量结果时,一般情况下报告扩展不确定度U。     

电能表检验装置测量不确定度的评定方法

详细论述了电能表检验装置测量不确定度的评定方法；介绍了怎样充分且合理地选择和确定测量不确定度的分量并将它们归为A类或B类标准不确定度以及怎样按国际惯例汇总和报告测量不确定度的结果。     

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.     

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.     

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.     

空压机轴承箱蜗壳温度探头油封改造

由于空压机进气侧轴承箱蜗壳温度探头密封效果不好,使空压机及其后续管道受到油污染。后将温度探头的O形圈密封改为骨架油封,杜绝了轴承箱漏油问题。文章简介空压机的结构和技术参数,详细介绍了骨架油封的制作和优点。     

Characteristics of mechanical properties of materials in studies of conditions of attainment of marginal states

It is shown that conditions of attainment of marginal states in the material of structural components are formulated on the basis of analysis of force and deformation criteria of formation and development of destruction. The parameters of these criteria are data on types of structural materials, standard and special characteristics of their mechanical properties, structural forms of considered elements of the equipment, and their operating stress loading. In this case, the construction of a system of state equations for describing interrelation of current damage, external actions, and responses to them is based on the concept of calculating variations in properties of materials at all stages of the design life cycle.     

Determination of parameters of microstructural inhomogeneity of deformation of metals by the method of modeling

The article suggests a method of evaluating the microstructural inhomogeneity of deformation of metals by modeling. The method includes the measurement of deformations of metal according to meshes of a dividing grid with small base and the calculation of the distribution parameters of microdeformations in model representation. It is shown that the modeling method makes it possible objectively to evaluate the microinhomogeneity of deformation of metals independently of the chosen mesh size of the dividing grid. New structural characteristics are introduced: the base and wave of variation expressing the degree of crumbling or amalgamation of metal grains by inhomogeneity of deformation.Translated from Problemy Prochnosti, No. 7, pp. 40–44, July, 1991.     

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.     

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)。