射频识别(RFID)读写器输出功率的测量不确定度评定

为了合理评定UHF频段射频识别读写器输出功率的测量不确定度,本实验室是在采用数字功率计加衰减器直接测量方法下建立的数学模型,对其测量不确定度的来源进行了分析,通过对测量列的A类评定,以及传感器系数、失配、衰减器误差等引入的不确定度分量的B类评定,从而给出了这种直接测量方法的测量合成不确定度和扩展不确定。     

测量不确定度评定及应用

对测量误差和测量不确定度的基本概念进行了分析,并举例说明了测量不确定度A类和B类评定以及测量结果给出的方法,为测量不确定度评定提供参考。     

0.02级活塞式压力计测量标准的不确定度评定

作为检定静态压力的计量标准,0.02级活塞式压力计测量标准的不确定度分析尤为重要。根据工作原理建立不确定度评定的数学模型,分析了不确定度来源,特别是对计量性能影响较大的因素进行了着重分析,最后对测量标准进行了A类和B类不确定度评定,给出测量标准的合成不确定度和扩展不确定度。     

压力变送器测量结果的不确定度分析与评定

按照JJG 882-2004《压力变送器检定规程》和JJF1059.1-2012《测量不确定度评定与表示》的要求,使用标准数字压力校验仪和标准数字多用表,对被检压力变送器检定结果进行误差分析,通过计算得到A类不确定度,通过分析得到B类不确定度,进而得到合成不确定度,对其测量结果进行了不确定度的分析与评定.     

露点仪测量结果的不确定度分析与评定

本文按照JJF 1272-2011《阻容法露点湿度计校准规范》和JJF 1059-1999《测量不确定度评定与表示》的要求,使用精密露点仪标准装置以及湿度发生器,对被检SHAW式露点仪的检定结果进行误差分析,通过计算得到A类和B类不确定度,进而得到合成不确定度,对其测量结果进行了不确定度分析与评定.     

水听器法的医用超声声场参数测量不确定度分析

提出了一种基于水听器法测量医用超声声场参数的测量装置,可通过扫描声场获取IEC 61157国际标准所要求的声场中峰值负声压等医用超声诊断设备的声输出参数.同时以一种B型超声诊断仪为例,对声场中声压的测量不确定度进行分析,分别给出A类、B类测量不确定度及标准不确定度,并对影响测量结果的主要因素进行了评定,得出当声压测定结果为1.456 4MHz时,其最小扩展不确定度可为0.215 0MHz.     

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。     

ICP-MS测定虾粉中砷含量的测量不确定度评定

建立电感耦合等离子体质谱(ICP-MS)测定虾粉中砷含量测量不确定度评定的数学模型。对数学模型中各个参数进行不确定度来源分析,分别对A类不确定度和B类不确定度进行评定。按照国际通用方法计算合成不确定度和扩展不确定度,当置信概率为95%,包含因子为k=2,其扩展不确定度为3.2 mg/kg。通过对不确定度来源的分析,指出标准曲线拟合是砷含量测量不确定度的主要来源。     

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。     

双光束激光多普勒测速实验系统的不确定度分析

激光多普勒测速技术被广泛应用于流体速度的测量。为减小双光束激光多普勒测速实验系统的测量误差,依据计量技术规范JJF 1059—1999 中规定测量不确定度的分析步骤和方法,针对系统的测量结果,从数学模型和测量方法2个方面,分析了流速测量中不确定度的主要来源。采用不确定度的A类评定和B类评定,对测量结果的各不确定度分量进行评定,得到了测量结果的合成标准不确定度和扩展不确定度。     

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)。