共查询到20条相似文献,搜索用时 46 毫秒
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测量不确定度的A类评定的几个问题 总被引:1,自引:0,他引:1
0 引言
标准不确定度的A类评定在计量检定不确定度评定中的应用越来越广泛,正确理解和使用标准不确定度的A类评定对于评定不确定度具有重要的意义。下文根据本人的一些理解谈谈利用A类评定标准不确定度容易出现的几个问题。 相似文献
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不确定度评定对于采用相对误差的涡轮流量计及标准装置,使用相对不确定度评定公式简洁,计算方便,本文介绍了使用相对不确定度对涡轮流量计系数不确定度进行评定的数学模型的建立过程、各分项不确定度的评定过程以及合成过程。 相似文献
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在实践中,笔者感到JJF1130—2005《几何量测量设备校准中的不确定度评定指南》对测量不确定度的实际评定具有很好的指导意义,通过对它的学习,有助于加深对JJF1059—1999《测量不确定度评定与表示》给出的不确定度评定规则的理解,使具体的不确定度评定变得规范、统一,有章可循,使复杂深奥的不确定度评定得以简化。满足测量的实际需要。 相似文献
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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. 相似文献
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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. 相似文献
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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)。 相似文献
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Liebert A Wabnitz H Grosenick D Möller M Macdonald R Rinneberg H 《Applied optics》2003,42(28):5785-5792
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. 相似文献
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