共查询到20条相似文献,搜索用时 187 毫秒
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标准物质的定值就是赋予标准物质特性量值的过程,标准物质作为计量器具的一种,它能复现、保存和传递量值,保证在不同时间和空间下量值的可比性和一致性。对于比表面积标准物质,目前国内外还无法进行绝对方法测量。现阶段,国内外比表面积标准物质的定值过程均采用多家实验室协同定值的方法。本文以国家纳米科学中心研制的纳米级氧化铝比表面积标准物质为实例,对比表面积标准物质的定值过程以及不确定度评定进行了详细介绍。 相似文献
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采用专用的白细胞、红细胞和血小板3类生物粒子合成模拟人的血液,按照国家一级标准物质研制规范制备血细胞计数标准物质,采用显微图像分析法为血细胞计数标准物质定值,对该血细胞计数标准物质的定值结果及不确定度评定、均匀性检验、稳定性检验过程进行分析,将该血细胞标准物质定值结果与国际参考方法的测定结果进行比对。结果证明:本血细胞计数标准物质适于血细胞分析仪的校准与计量检定。 相似文献
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介绍了影响微量一氧化碳气体标准物质定值的因素,包括定值方法的选取、原料气的选择、纯度检验和称量的方法。分别采用气相色谱仪的FID和PD—HID检测器对标准物质进行检测,确立了该标准物质的分析方法。对称量法制备微量一氧化碳气体标准物质过程中影响测量不确定度的因素进行了分析,评定了标准物质的不确定度。 相似文献
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介绍了氯化钾电导率溶液标准物质的研制方法,采用与一级标准物质比较定值的方法对该标准物质进行了定值,利用高精度电导率仪对定值结果进行了验证,同时对该标准物质进行了均匀性检验和稳定性考察。氯化钾电导率溶液标准物质的定值结果为1408μS/cm,扩展不确定度为:Urel=0.6%,k=2。其均匀性和稳定性检验结果表明,该标准物质符合国家二级标准物质的技术要求。 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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本文根据多年的实践检定经验 ,参照JJF1 0 59- 1 999《测量不确定度评定与表示》以及《测量不确定度表达 1 0讲》 ,对卧式金属罐容量的测量结果不确定度进行了评定。 相似文献