直流电桥电阻箱计量标准装置的建立

本文根据JJG166-93直流电阻器检定规程和JJG125-86直流电桥检定规程,建立了直流电桥电阻箱检定标准装置,根据不确定度评定方法,对此计量标准的测量结果进行了不确定度评定并进行了验证,同时测量了此计量标准的重复性和稳定性。     

直流电桥示值误差测量结果的不确定度分析与表示

文章主要依据JJG 125—2004《直流电桥检定规程》、JJF 1059—1999《测量不确定度评定与表示》,介绍了准确度等级0.2级QJ44携带型双电桥基本误差测量不确定度分析的方法。     

氧弹热量计热值误差测量不确定度评定

依据JJG672-2001《氧弹热量计》检定规程和JJF1059-1999《测量不确定度评定与表示》,本文对使用苯甲酸检定自动热量计的热值误差的测量不确定度的来源进行了分析,从而给出了使用苯甲酸检定自动热量计热值误差的测量结果的合成不确定和扩展不确定度。     

0.1～0.2级携带式直流双臂电桥示值误差的测量不确定度评定

依据ＪＪＧ１２－８６《直流电桥检定规程》,采用整体检定法,按ＪＪＧ１０５９－１９９９《测量不确定度评定与表示》对０．１～０．２级携带式直流双臂电桥示值误差的测量不确定度进行分析计算。     

电子秤化整前修正误差的测量不确定度评定

依据JJG539-1997《数字指示秤检定规程》检定电子秤(以下简称秤)；依据JJF1059-1999《测量不确定度评定与表示》评定被检秤化整前修正误差的不确定度。     

平板平面度测量结果不确定度评定探讨

按照JJF1059-1999测量不确定度评定与表示的要求,对JJG117-2005《平板检定规程》中的平面度测量结果不确定度重新进行公式推导计算,提出不同与《平板检定规程》中平面度测量结果不确定度评定与表示的方法,提高了测量结果的评定准确性。     

1级材料试验机示值误差的测量结果不确定度

本文介绍了依据JJG139-1999《拉力、压力和万能材料试验机检定规程》或JJG157-1995《非金属拉力、压力和万能试验机检定规程》,采用直接测量法,按JJF1059-1999《测量不确定度评定与表示》对1级材料试验机示值误差的测量结果不确定度的分析方法.     

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。     

机械天平测量不确定度评定

依据JJG98-2006《机械天平检定规程》JJG99-2006《砝码检定规程》及《JJF1059-1999测量不确定度评定与表示》。对天平校准过程中的不确定度进行分析、评定,并给出测量结果不确定度。     

直流电桥示值误差测量结果的不确定度评定

文章以直流电桥检定装置之主标准直流电阻箱z×78对直流单臂电桥QJ23检定为例,进行示值误差测量不确定度评定.     

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.     

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 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.     

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.     

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)。