测量不确定度的分析及应用

本文对测量误差和测量不确定度的基本概念作了简单介绍,得出测量结果的可靠程度是通过分析和评定测量不确定度来确定的;本文着重介绍和探讨了测量不确定度的计算步骤和计算方法,并结合电气实验室经常遇到的电压测量给出不确定度分析和计算实例;本文还介绍了单次测量条件下如何利用已知条件进行不确定度的估计以及不确定度的应用范围。     

产品质量检测不确定度的分析及应用

本文对测量误差和测量不确定度的基本概念作了简单介绍，得出测量结果的可靠程度是通过分析和评定测量不确定度来确定的；本文着重介绍和探讨了测量不确定度的计算步骤和计算方法，并结合电气实验室经常遇到的电压测量给出不确定度分析和计算实例；本文还介绍了单次测量条件下如何利用已知条件进行不确定度的估计以及不确定度的应用范围。     

基于FFT的舍入不确定度评估

舍入不确定度是快速傅里叶算法不确定度评估中的一个重要来源。将表示成向量矩阵的FFT算法分解为稀疏矩阵,以此确定信号传递流图,从而得出舍入不确定度在每一级的传递形式。再利用GUM中的B类方法对其进行评定,评定时假设舍入测量不确定度为均匀分布,通过对FFT算法中基-2算法的舍入不确定度进行评定,最终经过算法传递后得到其舍入不确定度的结果,在此基础上建立了FFT舍入测量不确定度的通用评估方法。     

量块比较测量法的不确定度分析

1　前言长期以来 ,我们将测量结果减被测量真值定为测量误差。因而测量结果的准确度用测量误差来表示。近年来为向国际标准靠扰 ,测量结果已采用测量不确定度取而代之。因为测量误差是未知的 ,而测量不确定度是可以根据期望的置信概率来估计。因此 ,对测量结果的可靠性 ,即误差的大小的估量用不确定度比用误差来描述更确切 ,更科学。2　比较测量不确定度来源及计算方法量块比较测量不确定度来源有以下几项 :(ａ)比较测量中所用标准量块长度的不确定度 ;(ｂ)被测与标准量块的温度差 ;(ｃ)被测与标准量块的线膨胀系数差 ;(ｄ)被测量块温度偏差…     

直流电位差计示值误差测量结果的测量不确定度评定

在测量过程中,测量结果都不可避免地具有测量不确定度,直流电位差计是一种常见的测量电压的仪器,它用一个已知电压与被测电压相平衡,该已知电压可以由可调电流流过固定电阻来获得,或者由它们的组合而获得。本文主要从方法概述、确定测量中不确定度分量、建立数学模型、计算相对标准不确定度分量、合成相对标准不确定度、扩展不确定度等入手,介绍了直流电位差计测量不确定度的评定过程。     

浅谈测量结果的不确定度

文章论述了测量不确定度的应用范围以及为什么用测量不确定度来代替评定等。     

采样计数法测量信号频率的不确定度

介绍了用数字化采样计数法评价周期信号频率时,测量结果的不确定度分析和评定过程,讨论了影响测量不确定度的几个主要误差来源;给出了减小测量不确定度的主要措施;在一组实际评价例子上,给出了其不确定度分析和评定结果,该过程及结论可应用信号频率的测量不确定度评定。     

测量不确定度在烟尘测试仪检定中的应用

测量结果不确定度的应用范围很广,从原则上说,在给出任何测量结果的同时均应该给出测量结果的不确定度。不确定度按其获得的方法分为A、B两类评定分量,若要得到某测量结果的不确定度,必须根据其仪器、设备、实验方法、人员素质、环境条件等因素提出完整的数学模型。本文依照具体情况给出本实验测量结果的不确定度。     

一种适用性更强的标准不确定度A类评定

测量不确定度往往由统计方法和非统计方法分别求得A类、B类标准不确定度后再合成得到。而采用统计方法一般需要一定数量的测量数据且知道其统计分布规律,这在实际中很难做到。本文给出一种求解标准差的方法,以此来评定测量不确定度,对数据量和分布规律无特殊要求,在实际应用中取得较好效果。     

工作用辐射温度计测量结果的不确定度评定

本文参照常用测量不确定度评定方法及应用实例,依据JJC415-2001《工作用辐射温度计检定规程》和工作经验,对工作用辐射温度计测量结果的不确定度进行了评定。     

基于NTN技术的宽带取样示波器过渡时间不确定度的研究

NTN技术是一种校准宽带取样示波器的新方法，NTN技术提供的测量量是kick—out脉冲响应（显示）波形数据，而宽带取样示波器的过渡时间是对kick—out脉冲响应波形数据进行反卷积分离等处理才能获得的导出量。提出了一种基于NTN技术的宽带取样示波器过渡时间的不确定度的全面评定方法。首先分析了NTN技术引入不确定度的主要因素，给出了不确定度计算公式；然后结合数据处理过程推导出不确定度的传递算法；最后给出了宽带取样示波器过渡时间不确定度的评定结果。     

On the operational definition of processing time uncertainty

The uncertainty of processing time has been reported to have a significant effect on the performance of dispatch rules. However, one noticeable result was that dispatch rules directly related to processing times were relatively insensitive to the uncertainty of processing time, while one might have previously expected otherwise. Actual processing times were generated in previous studies in such a way that variation of actual processing time increased together with uncertainty levels. As variation and uncertainty presented as one confounded factor in experiments, one question raised here is whether processing time uncertainty really has a substantial effect on the performance of dispatch rules. A two-stage approach used here investigated the current operational definition of processing time uncertainty by previous researchers and concluded that a new operational definition is desirable?one that isolates uncertainty rather than lumping it in with variation.     

基2快速傅里叶变换引入的不确定度估算

信号处理算法的不确定度研究是一个崭新的课题，快速傅里叶变换是一种基本的数字信号处理工具。通过分析基2快速傅里叶变换原理，分析了快速傅里叶变换的不确定度来源。以理论分析和数学推导方式研究了各主要不确定度分量，因此具有数学上的严格性。其中，将相关的栅栏效应和加窗截断引入的不确定度分量综合考虑，避开了分量之间的相关性。     

A High Sensitivity Microwave Sampling System with Adaptive Time-Drift Compensation

A new microwave sampling system is presented whose sensitivity has been increased by digital processing of the measurement data. The signal processing gets more complicated due to a time drift caused by electronic circuits in the sampling oscilloscope. An adaptive method to compensate for this time drift has been developed. The influence of noise is discussed, giving the remaining time uncertainty as a function of the signal-to-noise ratio. Finally an example illustrates how this method can be applied in an automatic sampling system.     

A New Method of Processing Mach–Zehnder Interference Fringe Data in Determination of Diffusion Coefficient

Laser holographic interferometry is the newest method to measure the mass diffusion coefficient and has been widely used in recent years. The processing of interference fringe images is a critical step of getting the final precise experimental results. On the basis of Fourier transformation and phase measurements, a new method of processing Mach–Zehnder interference fringes is introduced in this article. By experimental verification and uncertainty analysis, the accuracy of this method is validated. Mass diffusion coefficients of ethylene glycol dimethyl ether and diethylene glycol dimethyl ether, two new fuel additives in air were measured with the method introduced in this study.     

Auto-evaluation of the uncertainty in virtual instruments

A numerical approach based on a Monte Carlo probabilistic method is used as an advantageous alternative to the traditional analytical methods for the evaluation of the uncertainty in measurements achieved by digitally processing sampled input data. The correctness of the approach is shown in the case of both single-channel and multichannel systems. Some practical concerns about the reliability of the proposed methodology are discussed, and suitably designed virtual instruments are presented that are able to present the measurement result along with its uncertainty.     

乳腺腺体平均剂量2种测量数据处理方法的比较研究

针对医用乳腺X射线辐射源AGD测量数据处理过程中存在的难点问题,进行了试验研究,提出了2种有效的数据处理方法:近值法和线性拟合法。经过试验和比较得到以下结论:2种数据处理方法获得的测量结果及不确定度均符合相关技术规范要求,满足3Urel≤MPE的符合性判定准则。比较而言,线性拟合法获得的测量结果更加准确,其相对扩展不确定度(k=2)在5.7%～6.5%范围内,而近值法获得的相对扩展不确定度在6.4%～10%范围内。两种数据处理方法有效解决了医用乳腺X射线辐射源检定中不同模体厚度的转化因子和不同乳房成分修正因子如何确定的问题,为国家规程的下一步修订完善提供了参考,对其它同类测量数据的分析和处理也具有一定的借鉴作用。     

Method to reduce errors of droplet sizing based on the ratio of fluorescent and scattered light intensities (laser-induced fluorescence/Mie technique)

The droplet sizing accuracy of the laser technique, based on the ratio of laser-induced fluorescence (LIF) and scattered light (Mie) intensities from droplets, is examined. We develop an analytical model of the ratio of fluorescent to scattered light intensities of droplets, which shows that the LIF/Mie technique is susceptible to sizing errors that depend on the mean droplet size and the spread of the droplet size distribution. The sizing uncertainty due to the oscillations of the scattered light intensity as a function of droplet size is first quantified. Then, a new data processing method is proposed that can improve the sizing uncertainty of the technique for the sprays that were examined in this study by more than 5% by accounting for the size spread of the measured droplets, while improvements of 25% are possible when accounting for the mean droplet size. The sizing accuracy of the technique is evaluated in terms of the refractive index of liquid, scattering angle, and dye concentration in the liquid. It is found that the proposed approach leads to sizing uncertainty of less than 14% when combined with light collection at forward scattering angles close to 60° and the lowest fluorescent dye concentration in the liquid for all refractive indices.     

Uncertainty considerations in AC loss measurement of multifilamentary superconducting wires performed via a pickup coil method

The uncertainty of AC loss measurements for multifilamentary superconducting wires by a pickup coil method is evaluated on the basis of the law of propagation of uncertainty. In this evaluation, the effects of measurement conditions, signal processing, and the division of the AC loss into its components (hysteresis loss and coupling loss) are taken into account as elements of uncertainty. The effect of the measurement conditions is evaluated using theoretical expressions of the two main components. Additionally, the effect of signal processing is considered in accordance with the actual processes of the AC loss measurement using experimental outputs. The main factors that contribute to the uncertainty in the propagation process are discussed. The estimated resultant uncertainties are compared to experimental ones for round robin tests of AC loss measurement of Nb-Ti multifilamentary wires exposed to an alternating transverse magnetic field.     

A method based on random-fuzzy variables for online estimation of the measurement uncertainty of DSP-based instruments

The evaluation of the uncertainty of the result of a measurement performed by a DSP-based instrument is usually a complex and difficult task. The sources of uncertainty are the instrument input stage and the analog-to-digital converter (ADC), so that each input sample to the instrument can be considered a measurement result with its associated uncertainty. The uncertainty on the final measurement result is obtained as the combination of the uncertainty values of each sample, according to the measurement algorithm implemented on the digital signal processing (DSP) system. This paper proposes an innovative approach, based on the representation of the measurement result and its associated uncertainty in terms of random-fuzzy variables, that, after having suitably characterized the metrological performance of the input stage and analog-to-digital converter, provides an online estimation of the measurement uncertainty. The method has been validated experimentally, and the results of the experimental work are reported.