电子式绝缘电阻表检定装置测量值的不确定度评定

本文分析了用电子式绝缘电阻表检定装置测量值的不确定度来源,对绝缘电阻测量不确定度进行了评定。     

绝缘电阻表测量值的不确定度评定

介绍了绝缘电阻表测量结果不确定度评定的方法。运用GUM法对绝缘电阻表100V档50MΩ点的测量结果不确定度进行评定,从重复性、标准装置最大允许误差和最小步进等6个方面分析影响测量结果的不确定度因素。结果表明标准装置最小步进和环境温度对测量结果的影响很小,可忽略。GUM法简单、高效、精度高,适用于绝缘电阻表测量结果不确定度的评定。     

接地电阻表测量值不确定度评定

本文介绍了接地电阻表检定装置测量值不确定度评定方法。     

电子式绝缘电阻表示值误差的不确定度评定

电子式绝缘电阻表是工业生产中用于测量电气设备电阻值的常用仪表之一。文章结合检校工作实际,按照测量不确定度评定的方法和步骤,对电子式绝缘电阻表的测量结果进行不确定度评定。     

绝缘电阻表检定装置中的测量不确定度评定

绝缘电阻表检定装置的测量不确定度的来源主要是人员(读数误差)、方法(定义、测量方法等)、测量环境、测量装置(测量仪器和辅助设备等)四个方面。在评定测量不确定度时应先建立数学模型,根据数学模型的各输入量从这四个方面进行考虑,这样在评定过程中就会做到既不重复也不遗漏。一、概述1.评定依据JJF1059-1999《测量不确定度评定与表示》技术规范JJG622-1997《绝缘电阻表》检定规程2.测量标准ZX119-2型兆欧表标准可调式高阻箱[(0.01～11111.10)MΩ,±(0.2%～2%)]Q5-V型静电电压表[(0～3)kV,±1%]3.测量方法和测量过程采用直接比较法,…     

电子式绝缘电阻表测量不确定度分析报告

依据JJG 1005—2005《电子式绝缘电阻表检定规程》,采用标准电阻法,测得被测绝缘电阻表绝缘电阻示值误差,采用比较测量法。建立了测量结果的不确定度的数学模型,并计算了其测量结果的扩展不确定度。     

电子式绝缘电阻表示值误差测量结果的不确定度评定

本文根据JJG1005-2005电子式绝缘电阻表检定规程对电子式绝缘电阻表电阻示值进行测量,并对测量过程中不确定度的来源进行分析,对各分量进行了详细量化,计算出该分析方法的合成标准不确定度,并给出结果的扩展不确定度。     

模拟式绝缘电阻表读数引入的不确定度分析

在模拟式绝缘电阻表的测量不确定度评定过程中,读数的人为偏移引入的不确定度在最终的测量不确定度评定结果中具有显著的贡献。忽略读数引入的不确定度会使最终的测量不确定度偏小,近似取分辨力引入的不确定度会使最终的测量不确定度不够准确,而现有文献关于读数引入的不确定度相关研究较少。文章介绍了一种模拟式绝缘电阻表读数引入的不确定度评定方法,并对其进行简化,最后通过举例说明该方法的适用性。     

三相交直流仪表检定装置的直流电压测量结果不确定度评定

本文介绍了依据JJG124-2004《电流表、电压表、功率表及电阻表》,用三相交直流仪表检定装置,输出标准直流电压值对直流电压表进行检定的方法,以及测量结果的不确定度的评定.     

三相交直流仪表检定装置的直流电压测量结果不确定度评定

本文介绍了依据JG124-2004<电流表、电压表、功率表及电阻表>,用三相交直流仪表检定装置,输出标准直流电压值对直流电压表进行检定的方法,以及测量结果的不确定度的评定.     

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)。