基于贝叶斯理论的测量不确定度A类评定

文章介绍了贝叶斯理论，并利用此理论对测量不确定度A类评定进行分析，与基于经典统计方法的不确定度A类评定相比，该方法能充分利用历史测量数据所提供的信息，因此评定时信息量大，使评定更加合理。最后通过实例分析说明了基于贝叶斯理论的不确定度A类评定的合理性和优越性。     

Evaluation of laboratory performance through interlaboratory comparison

This paper reports the performance of the calibration results obtained by 21 laboratories using digital pressure calibrator as an artifact in the pressure range 7–70 MPa. National Physical Laboratory (NPLI), New Delhi has coordinated this programme and also acted as a reference laboratory. The program started in May, 2006 and completed during May, 2008. The comparison was carried out at 10 equally spaced pressure points i.e. 7,14,21,28, 35,42,49,56, 63 and 70 MPa throughout the entire pressure range of 7–70 MPa. The calibration results thus obtained were analyzed as per ISO / IEC GUM document. The 92.7 % measurement results are found in agreement with the results of NPLI. The relative deviations between laboratories values and reference values are well within the 0.05 %for 123 measurement points, 0.1% for 162 measurement points and 0.25% for 177 measurement points. The difference of the laboratories values with reference values are found almost well within the uncertainty band of the reference values at 68.0 % measurement results, within their reported expanded uncertainty band at 81.5% measurement results and within the combined expanded measurement uncertainty band at 92.7 % measurement results. Overall, the results are considered to be reasonably good being the first proficiency testing for most of the participating laboratories.     

New concept of IEC standards for radiation protection dosemeters

The International Electrotechnical Commission (IEC) develops new standards for radiation protection dosemeters which follow a new concept. They are much more flexible in detail, but still ensure the same measurement quality. They are, for example, no longer specific for the detector type, but rather specific for the measurement task, e.g. for individual monitoring with active direct-reading instruments. Another example is that they are flexible with respect to the ranges of influence quantities. The conceptual changes are described in this paper, together with the advantages this new concept provides for manufacturers, users and legislators.     

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.     

Sound Pressure Level in an Infant Incubator

Currently, there are a lot of infant incubators being used in hospitals in Thailand. That situation brings about the question on whether the values of physical quantities such as sound pressure or temperature inside the incubator still conform to the requirements of the international standards. The main objective of this research was to study the sound pressure level (SPL) generated within the incubator. The measurement method was based on IEC 60601-2-19:2009. There were two measurement conditions of the SPL in the infant incubator; the measurement during power-off condition and the measurement during the operation of incubator at a controlled temperature of 36 °C with a maximum humidity setting. Both measurement conditions were carried out in an empty incubator. The average values from the three measurement results of each operating incubator subtracted by the value of background noise were reported as the result of SPL generated in the incubator. The SPL results from this study were lower than 60 dBA, which are within the tolerance limit specified in IEC 60601-2-19. The estimated measurement uncertainty was lower than 1.8 dBA. This research will benefit to an investigation of hearing loss in infants possibly caused by the operation of the infant incubators in Neonatal Intensive Care Unit (NICU). Ultimately, this research will be a great evidence to show the NICU staffs in the hospitals in Thailand and also raise their awareness that it is important to sustain the proper maintenance and calibration of the infant incubators.     

球面聚焦声场自易法从GB/T 32522-2016到IEC TS 62903-2018的技术进步

文章叙述了《球面聚焦超声换能器的电声特性和声功率测量》的自易法校准成为国家标准方法后,进而以其为基础在起草国际电工委员会技术规范的过程中,所做的主要技术进步,包括:理论叙述的改进、一些错误概念的修正、最新研究成果的吸纳、全频段实验验证、测量不确定度估计等重要方面。     

Uncertainty Evaluation of the New Setup for Measurement of Water-Vapor Permeation Rate by a Dew-Point Sensor

The measurement of the water-vapor permeation rate (WVPR) through materials is very important in many industrial applications such as the development of new fabrics and construction materials, in the semiconductor industry, packaging, vacuum techniques, etc. The demand for this kind of measurement grows considerably and thus many different methods for measuring the WVPR are developed and standardized within numerous national and international standards. However, comparison of existing methods shows a low level of mutual agreement. The objective of this paper is to demonstrate the necessary uncertainty evaluation for WVPR measurements, so as to provide a basis for development of a corresponding reference measurement standard. This paper presents a specially developed measurement setup, which employs a precision dew-point sensor for WVPR measurements on specimens of different shapes. The paper also presents a physical model, which tries to account for both dynamic and quasi-static methods, the common types of WVPR measurements referred to in standards and scientific publications. An uncertainty evaluation carried out according to the ISO/IEC guide to the expression of uncertainty in measurement (GUM) shows the relative expanded (k = 2) uncertainty to be 3.0 % for WVPR of 6.71 mg . h^?1 (corresponding to permeance of 30.4 mg . m^?2. day^?1 . hPa^?1).     

Flicker responses of different lamp types

Nowadays, more and more lamp types are being used. Since different lamp types have different working principles, they also have different flicker responses. This paper shows the measurement results of different flicker responses for various types of lamps. These results prove that the UIE/IEC flickermeter, which has been used widely around the world for many years, cannot be used to advise on the flicker level of all lamp types. This is because of the fact that this flickermeter is based on a 230 V, 60 W or 120 V, 60 W incandescent lamp and can be used as reference only for this type of lamp or as reference to the standard. The UIE/IEC (International Union for Electricity Applications/International Electrotechnical Committee) flickermeter and the existing standards are therefore insufficient for other lamp types. This paper describes a proposal to improve the UIE/IEC flickermeter.     

Accurate Software-Related Average Current Drain Measurements in Embedded Systems

Performing accurate average current drain measurements of digital programmable components (e.g., microcontrollers, digital signal processors, System-on-Chip, or wireless modules) is a critical and error-prone measurement problem for embedded system manufacturers due to the impulsive time-varying behavior of the current waveforms drawn from a battery in real operating conditions. In this paper, the uncertainty contributions affecting the average current measurements when using a simple and inexpensive digital multimeter are analyzed in depth. Also, a criterion to keep the standard measurement uncertainty below a given threshold is provided. The theoretical analysis is validated by means of meaningful experimental results     

Measurement of the detective quantum efficiency (DQE) of digital X-ray detectors according to the novel standard IEC 62220-1

A mobile measurement facility which complies with IEC 62220-1 has been set up to determine the detective quantum efficiency (DQE) of digital X-ray detector systems. Exemplary measurements were performed for two similar CR detector systems, a CsI-based indirect detector and an Se-based direct detector. The standardised radiation quality RQA 5 was applied for measurement and for three of these systems RQA 9 was also applied. A pronounced dependence of DQE on radiation quality was observed for the direct detector, where the DQEs for RQA 5 and RQA 9 differ by a factor of approximately 2. The uncertainty (95% confidence interval) associated with the measured DQE values is within 0.01 and 0.04 depending on, for example, the spatial frequency. Thus, it has been demonstrated that the DQE can be measured accurately and reliably with the accuracy required by the international standard IEC 62220-1. It is now possible to objectively measure and compare DQE values of digital X-ray detector systems.     

The use of a Monte Carlo method for uncertainty calculation, with an application to the measurement of neutron ambient dose equivalent rate

This paper is concerned with the use of a Monte Carlo method for uncertainty calculation as an implementation of the propagation of distributions. It reviews the basic principles of the propagation of distributions and numerical aspects of a Monte Carlo implementation. It also discusses the possible advantages in some circumstances of the propagation of distributions over the GUM uncertainty framework, and how the results obtained in any particular instance can be compared with those provided by that framework. To illustrate these various aspects, an application to the measurement of neutron dose equivalent rate is given. A key consideration in this application is the manner in which the dominant source of uncertainty, namely that associated with the field-specific correction factor, is treated. The information available concerning this factor constitutes the correction factors for a set of fields of the same type as that in which a measurement is being made. This information is encoded as a probability density function (PDF) for the correction factor. This PDF constitutes an input to both methods of evaluation.     

Validation of Calculations in a Digital Thermometer Firmware

State-of-the-art digital thermometers are arguably remarkable measurement instruments, measuring outputs from resistance thermometers and/or thermocouples. Not only that they can readily achieve measuring accuracies in the parts-per-million range, but they also incorporate sophisticated algorithms for the transformation calculation of the measured resistance or voltage to temperature. These algorithms often include high-order polynomials, exponentials and logarithms, and must be performed using both standard coefficients and particular calibration coefficients. The numerical accuracy of these calculations and the associated uncertainty component must be much better than the accuracy of the raw measurement in order to be negligible in the total measurement uncertainty. In order for the end-user to gain confidence in these calculations as well as to conform to formal requirements of ISO/IEC 17025 and other standards, a way of validation of these numerical procedures performed in the firmware of the instrument is required. A software architecture which allows a simple validation of internal measuring instrument calculations is suggested. The digital thermometer should be able to expose all its internal calculation functions to the communication interface, so the end-user can compare the results of the internal measuring instrument calculation with reference results. The method can be regarded as a variation of the black-box software validation. Validation results on a thermometer prototype with implemented validation ability show that the calculation error of basic arithmetic operations is within the expected rounding error. For conversion functions, the calculation error is at least ten times smaller than the thermometer effective resolution for the particular probe type.     

Unscented transform: a powerful tool for measurement uncertainty evaluation

An original approach for uncertainty evaluation in indirect measurements is presented hereinafter. The approach applies the unscented transform to the measurement model (i.e., the functional relationship between output and input quantities) in order to gain a reliable estimate of output expectation and standard deviation (measurement uncertainty). Thanks to some useful properties of the transform, notable limits of the current GUM recommendations can be overcome. In particular, reliable estimates are also granted in the presence of nonlinear and/or nonanalytical measurement models or complex digital signal processing algorithms. A number of numerical tests are conducted on simulated and actual measurement data. Remarkable concurrence between obtained estimates and those granted by Monte Carlo simulations confirms the efficacy of the proposed approach.     

关于影像密度测量时光谱条件的探讨

本文概括阐明了由ISO规定,通常用在不同影像技术工作中的主要几种光学密度测量的光谱条件。如:视觉密度、1类型和2类型印片密度、A状态和M状态密度。同时也介绍了光谱乘积的简明定义和教学表达式以及相关数据,且附有有关问题的简单讨论。     

心电图机内定标电压示值误差测量结果的不确定度评定

本文针对国内广泛使用的内蒙古计量所生产的EGC-1B心脑电图机检定仪，在检定心电图机内定标电压示值误差时的不确定度评定方法进行了探讨，并系统地研究了影响测量结果的各分量及函数传递关系，得出了典型心电图机内定标电压示值误差不确定度。可供从事心电图机检测工作的相关人员参考。     

A Careful Consideration of the Calibration Concept

This paper presents a detailed discussion of the technical aspects of the calibration process with emphasis on the definition of the measurand, the conditions under which the calibration results are valid, and the subsequent use of the calibration results in measurement uncertainty statements. The concepts of measurement uncertainty, error, systematic error, and reproducibility are also addressed as they pertain to the calibration process.     

采样序列长度及周波数对正弦参数拟合的影响

针对波形拟合法估计正弦参数时,测量条件对拟合参数带来的误差影响,进行了拟合误差界的搜索研究。选取的条件变量分别是A/D位数、幅度、序列所含波形的周波数、初始相位、直流分量以及序列数据点数。以两两联动的双条件组合方式进行误差界搜索,获得了幅度、频率、相位、直流分量、动态有效位数等拟合参数的误差界随不同条件变化而变化的曲线规律,筛分出了显著影响量和不显著影响量。并对A/D位数、序列所含波形的周波数、以及序列数据点数带来的影响进行了深入研究,获得了拟合参数的误差界呈现量子化阶梯特征的显著规律,并获得了量子化阶梯边界点估计的经验公式。该结果可用于拟合正弦参数的误差评价和不确定度估计,也可以用于在设定拟合误差和不确定度情况下,选择测量条件。     

X70管线钢洛氏硬度试验结果的不确定度评定

依据GB／T230．1—2009规定的试验方法,利用Wilson 2001T洛氏硬度计对某钢厂X70管线钢进行了洛氏硬度（HRB）试验,从试验重复性、硬度计复现性等多方面对洛氏硬度试验的不确定度来源进行了分析和阐述,对每个不确定度分量进行了逐一评定,最终给出了扩展不确定度及测量结果的不确定度报告。结果表明：该X70管线钢洛氏硬度测量平均值为（78．5±2．4）HRB,包含因子k=2。该方法对金属材料洛氏硬度的测量不确定度评定具有一定的参考价值。     

电压驻波比测量不确定度的评定和表述

电压驻波比是无线电领域表征反射特性的传统参量,目前仍有应用场景,然而一些实验室对电压驻波比测量不确定度的报告是不完善的。比较了GUM法线性模型、GUM法非线性模型和蒙特卡洛法对电压驻波比测量不确定度的评定结果,给出了一种在常规测量条件下可代替蒙特卡洛法的快速估算方法,并将该方法推广到一元非线性测量模型。