Comparison of GUF and Monte Carlo methods to evaluate task-specific uncertainty in laser tracker measurement

Measurement uncertainty plays an important role in laser tracking measurement analyses. In the present work, the guides to the expression of uncertainty in measurement(GUM) uncertainty framework(GUF) and its supplement, the Monte Carlo method, were used to estimate the uncertainty of task-specific laser tracker measurements. First, the sources of error in laser tracker measurement were analyzed in detail, including instruments, measuring network fusion, measurement strategies, measurement process factors(such as the operator), measurement environment, and task-specific data processing. Second, the GUM and Monte Carlo methods and their application to laser tracker measurement were presented. Finally, a case study involving the uncertainty estimation of a cylindricity measurement process using the GUF and Monte Carlo methods was illustrated. The expanded uncertainty results(at 95% confidence levels) obtained with the Monte Carlo method are 0.069 mm(least-squares criterion) and 0.062 mm(minimum zone criterion), respectively, while with the GUM uncertainty framework, none but the result of least-squares criterion can be got, which is 0.071 mm. Thus, the GUM uncertainty framework slightly underestimates the overall uncertainty by 10%. The results demonstrate that the two methods have different characteristics in task-specific uncertainty evaluations of laser tracker measurements. The results indicate that the Monte Carlo method is a practical tool for applying the principle of propagation of distributions and does not depend on the assumptions and limitations required by the law of propagation of uncertainties(GUF). These features of the Monte Carlo method reduce the risk of an unreliable measurement of uncertainty estimation, particularly in cases of complicated measurement models, without the need to evaluate partial derivatives. In addition, the impact of sampling strategy and evaluation method on the uncertainty of the measurement results can also be taken into account with Monte Carlo method, which plays a guiding role in measurement planning.

Model and methods for comprehensive measurement of the low-carbon status of China's oil and gas enterprises

This paper establishes a model that would allow China＇s oil and gas enterprises to scientifically evaluate and measure their low-carbon level and status. It considers various characteristics of China＇s oil and gas enterprises and the implications of low-carbon development, and is based on an overall analysis of factors that influence the reduction of carbon emissions. In view of low-carbon economic theories and the general principles of an evaluation index system, a comprehensive system for measuring the low-carbon status of China＇s oil and gas enterprises has been developed. This measurement system is comprised of four main criteria （energy structure, energy utilization, carbon emissions and utilization, and low carbon management） as well as thirty indexes. By the Delphi method and the analytical hierarchy process （AHP）, the weight of the rules hierarchy and indexes hierarchy were determined. The standardized indexes were then integrated using a linear weighted sum formula, and a comprehensive formula for index measurement was established. Taking into account the status of low- carbon development in the petroleum and petrochemical industry at home and abroad, an evaluation criterion is proposed comprising four levels： ideal low-carbon, economical low-carbon, medium-carbon and high-carbon, whose values were organized within the settings of [0, 1].

Fire risk evaluation research on fully mechanized coalface based on the uncertainty measure theory

A relatively perfect coalmine fire risk-evaluating and order-arranging model that includes sixteen influential factors was established according to the statistical information of the fully mechanized coalface ground on the uncertainty measure theory.Then the single-index measure function of sixteen influential factors and the calculation method of computing the index weight ground on entropy theory were respectively established.The value assignment of sixteen influential factors was carried out by the qualitative analysis and observational data, respectively, in succession.The sequence of fire danger class of four experimental coalfaces could be obtained by the computational aids of Matlab according to the confidence level criterion.Some conclusions that the fire danger class of the No.1, No.2 and No.3 coalface belongs to high criticality can be obtained.But the fire danger class of the No.4 coalface belongs to higher criticality.The fire danger class of the No.4 coalface is more than that of the No.2 coalface.The fire danger class of the No.2 coalface is more than that of the No.1 coalface.Finally, the fire danger class of the No.1 coalface is more than that of the No.3 coalface.

Relative Performance Evaluation of Competing Crude Oil Prices’ Volatility Forecasting Models: A Slacks-Based Super-Efficiency DEA Model

With the increasing number of quantitative models available to forecast the volatility of crude oil prices, the assessment of the relative performance of competing models becomes a critical task. Our survey of the literature revealed that most studies tend to use several performance criteria to evaluate the performance of competing forecasting models;however, models are compared to each other using a single criterion at a time, which often leads to different rankings for different criteria—A situation where one cannot make an informed decision as to which model performs best when taking all criteria into account. In order to overcome this methodological problem, Xu and Ouenniche [1] proposed a multidimensional framework based on an input-oriented radial super-efficiency Data Envelopment Analysis (DEA) model to rank order competing forecasting models of crude oil prices’ volatility. However, their approach suffers from a number of issues. In this paper, we overcome such issues by proposing an alternative framework.

1200 kV雷电冲击电压标准测量系统

目前,冲击电压测量系统溯源所需的国家计量标准系统额定电压只有700 kV,无法满足3500 kV及以上的特高压电器的溯源需求。对研制的1200 kV电阻分压器进行结构分析,并对建立的1200 kV冲击电压测量系统进行性能测试及改进,在700 kV电压范围内与已有的700 kV冲击电压国家标准测量系统进行比对校准,在700 kV至1200 kV电压范围进行线性度实验。对1200 kV标准冲击电压测量系统进行了不确定度评定,评定结果表明研制的1200 kV雷电冲击电压标准测量系统的试验电压、波前时间、半峰值时间的测量误差均在国际标准IEC 60060及国家标准GB/T 16927允许范围内,将我国的冲击电压国家标准测量系统额定电压等级提高至1200 kV。

水流速装置比对传递标准的评价方法研究

水流速装置是各式流速仪的检定校准装置,为考察各实验室装置量值复现的准确性,可实施装置间的计量比对。拟选用两台测速原理不同的流速仪作传递标准,针对仪器的测量重复性、长期稳定性和安装条件等在传递过程中会对比对结果产生影响的因素开展实验,并完成测量结果不确定度评定。在规定的考察时间和流速范围内,两台新流速仪做相同流速点测试实验。LS1206B转子式流速仪在测试中测量重复性保持在0.1%以下,稳定性在0.5%范围内,较之于Vector性能表现更好;LS1206B的水力螺距测量不确定度在高流速下更小,其不确定度主要来源有标准装置引入的流速不确定度、测量重复性引入的不确定度和仪器安装偏角引入的不确定度;若实际安装时偏角较大,会严重影响测量结果进而影响比对结果。另一台Vector声学多普勒流速仪在良好的信噪比环境下,重复性和稳定性都在1%以内,其不确定度来源有装置引入的流速不确定度和测量重复性引入的不确定度。

基于瞬态热桥法的固体材料导热系数测量及其不确定度的评定

在Hammerschmidt建立瞬态热桥(THB)法理论的基础上,改进了恒定输入电流模式下导热系数解析模型和修正模型,对THB测量传感器进行了结构设计和仿真验证。搭建了测量范围为0.01~150 W/(m·K)的实验装置,并对修正模型进行了测量验证。对聚苯乙烯、有机玻璃和45号钢等7种固体材料进行了实验测量,对测量结果进行了不确定度的评定,并与不同仪器的测量结果进行了比较。结果表明,实验装置的测量重复性优于1.7%,与参考值的相对偏差在±5%以内,经评定测量结果的相对扩展不确定度为U_(rel)=2.94%(k=2)。

无创自动测量血压计静态压力示值误差测量结果的不确定度评定

电子血压计作为测量人体血压最常见的设备之一,不确定度的评定是判定测量值准确与否的重要指标。本文介绍示波法原理的无创自动测量血压计静态压力示值误差测量结果的不确定度评定和表达方法。

实验室内分泌项目测量不确定度的评定研究

目的 采用“自上而下”的方法评定内分泌试验检验项目的测量不确定度。方法 采用CNAS-CL01-G003:2021《医学实验室—测量不确定度的评定与表达》技术报告中的“自上而下”的方法,收集实验室的室内质控数据和2019—2021年北京市临床检验中心的室间质评结果,评定游离三碘甲状腺原氨酸(free triiodothyronine,FT_(3))、总三碘甲状腺原氨酸(total triiodothyronine,TT_(3))和游离甲状腺素(free thyroxine,FT_4)等11项内分泌试验检测指标的测量不确定度。结果 11项内分泌试验检测项目在低浓度水平时的相对扩展不确定度分别为FT_(3):12.658%、TT_(3):13.372%、FT_4:10.468%、总甲状腺素(total thyroxine,TT_4):32.382%、促甲状腺激素(thyroid stimulating hormone,TSH):8.594%、雌二醇(estradiol,E_(2)):18.656%、卵泡刺激素(follicle-stimulating hormone,FSH):14.650%、促黄体生成素(luteinizing hormone,LH):29.384%、孕酮(progesterone,PRO):28.806%、催乳素(prolactin,PRL):13.810%、睾酮(testosterone,TESTO):31.610%;在正常浓度水平时的相对扩展不确定度分别为FT_(3):12.424%、TT_(3):12.462%、FT_4:8.606%、TT_4:14.130%、TSH:12.536%、E_(2):19.586%、FSH:14.382%、LH:23.400%、PRO:38.346%、PRL:16.014%、TESTO:39.352%;在高浓度水平时的相对扩展不确定度分别为FT_(3):13.882%、TT_(3):14.096%、FT_4:11.040%、TT_4:8.614%、TSH:7.782%、E_(2):14.366%、FSH:13.436%、LH:14.804%、PRO:11.574%、PRL:17.742%、TESTO:39.322%。TT_4、LH在低浓度水平附近时、PRO在低浓度和正常浓度水平附近时、TESTO在3种浓度水平附近时的相对扩展测量不确定度高于目标不确定度(25%),其余项目均小于目标不确定度。结论 利用实验室的质控数据,可评定美国雅培i2000SR全自动化学发光免疫分析仪对FT_(3)、TT_(3)、FT_4等11个内分泌检测项目的测量不确定度,具有一定的临床应用价值。

钢砧校准方法的研究及其测量不确定度评定

钢砧作为回弹仪率定试验的重要计量器具,其量值准确与否关系到回弹仪是否合格,从而影响混凝土等建筑材料抗压强度的检测。该文通过对钢砧工作原理和校准方法的研究,建立钢砧的测量模型,并对其计量参数的测量不确定度进行评定,为钢砧校准研究提供参考。

电位法测定土壤pH值不确定度评定

土壤pH值是土壤分析中的一项重要指标,许多土壤分析项目需要根据土壤的pH值进行选择相应的分析方法,检测结果也都与土壤pH值有关联,是审核其他项目结果的重要依据。本文根据测量不确定度评定理论,结合电位法对土壤pH值测量不确定度进行全面分析。从测定的重复性、样品称重、浸提前处理、仪器示值误差、仪器校准5个方面归纳不确定度来源,对各不确定度分量详细评定,并由各不确定度分量合成得到土壤pH值测定的相对标准不确定度及扩展不确定度,得出土壤pH值的测量不确定度为8.24±0.03。在分析过程中,对比各个不确定度分量对土壤pH值测定不确定度的贡献大小,其中pH标准缓冲溶液校准引入的不确定度分量最大。

基于GUM法的城轨扣件动刚度测量不确定度评定

扣件是城市轨道交通设备设施中的重要组成部件之一,新型号的扣件在投入使用前或者在用扣件在进行日常运维检查时,需要进行多个参数的测量,以验证其是否符合相关标准。为评定城轨扣件动刚度测量不确定度,文章对该项测量结果的不确定度主要来源进行分析,采用GUM法对其关键测量不确定度分量进行评定,计算得到在符合标准要求条件下的城轨扣件动刚度测量不确定度。不确定度的加入可使该项测试结果更加准确、可信,计算过程也可为相关检测机构工作人员进行城轨扣件其他参数测量不确定度评定工作提供参考。

路基路面野外观测站土壤水分传感器标定方法研究

为探明路基路面野外观测站土壤水分传感器的有效标定方法,以准确监测不同环境条件下公路路基路面各结构层含水率的量值及变化规律,采用标准土样法对拟用于三江至柳州高速公路路基路面野外观测站的土壤水分传感器进行了标定,并以观测站钻孔施工挖出的路基土样为比对土样,将传感器法与烘干法的测量结果进行了比对分析,验证了标准土样法标定土壤水分传感器的有效性与适用性,对制定合理有效的公路工程专用土壤水分传感器校准规范具有重要的参考意义。结果表明:标准土样法是有效的路基路面野外观测站土壤水分传感器标定方法。

基于智能分析的油水井生产预警技术研究

利用油水井勘探开发过程中的海量数据,分析并识别出生产异常的油水井,对异常变化深入查探,据此提出针对性措施,对维持油田稳定开采、产量高效保持,实现最大化生产效益具有重要意义。通过大数据分析与神经网络预测方法,利用措施数据库进行机器学习、训练模型,建立不同增产措施的神经网络模型,形成基于静态油藏数据、动态生产数据和措施方案参数的增产效果预测评价系统。

扭矩扳子计量比对及其结果分析

为了解扭矩扳子量值溯源传递实验室的环境条件和计量器具准确度,考察检测人员技术水平,开展扭矩扳子计量比对。介绍扭矩扳子比对技术方案,对比分析比对结果,发现扭矩扳子的计量检定工作中存在问题。针对扭矩扳子计量比对中存在的问题,提出改进措施,以便提高检测水平,保证量值传递工作的准确性和一致性。

扭矩套筒示值误差测得值的不确定度评定

针对风电、电力、铁路等行业对螺栓高精度装配扭矩的要求,基于数显扭矩套筒的实际测量数据,采用具体示例详细阐述分析方法,对示值误差测得值进行不确定度评定,为有效解决其量值溯源提供参考。

基于影像测量的三等标准金属线纹尺检定不确定度评定

以激光干涉仪为主标准器,结合显微镜瞄准和CCD影像采集装置检定三等金属线纹尺的实际长度,已成为目前常用的检定方法。文中从多个方面分析该方法检定三等金属线纹尺实际长度的测量不确定度来源,得到满足要求的评定结果。

铁路轨道信号在线测量仪补偿电容检定结果不确定度评定

为了保障铁路轨道信号在线测量仪测得的ZPW-2000A轨道电路补偿电容容值准确、可靠,依据JJG(铁道)702—2021《铁路轨道信号在线测量仪检定规程》,利用XHBQ-Ⅰ型轨道信号测试设备综合校验仪,检定铁路轨道信号在线测量仪。介绍检定方案,评定补偿电容检定结果不确定度,并进行验证。结果表明,检定方案满足量值传递要求,能保证铁路轨道信号在线测量仪测量的电容结果准确、可靠。

电感耦合等离子体发射光谱法测定稀土镁硅铁合金中镁含量的不确定度评定

本文对电感耦合等离子体发射光谱法测定稀土镁硅铁合金中镁元素含量的测量不确定度进行评定。根据检测方法及数学模型,从标准物质、校准拟合曲线、样品称量、定容、稀释及重复测定等方面分析不确定度来源,并计算对应的相对标准不确定度,同时将各个分量进行合成并拓展。计算得:当稀土镁硅铁合金中镁元素含量为7.12%时,其扩展不确定度为0.19%(取置信区间为95%,包含因子k=2)。通过评定结果表明,标准溶液配置过程、重复测定、校准曲线拟合及样品溶液稀释过程对测定结果影响较明显。

GF-AAS与ICP-MS测定水中总铬含量的方法比对及其不确定度评定

石墨炉原子吸收光谱(GF-AAS)法和电感耦合等离子体质谱(ICP-MS)法是灵敏度较高的2种测定水中铬含量的方法。文中采用357.9 nm与429.0 nm波长条件下GF-AAS法、52与53质核比条件下ICP-MS法测定水质铬标准物质中总铬元素含量,从标准曲线、准确性、重复性、加标回收率、检出限、定量限、测量不确定度评定多个方面进行对比分析。结果表明,4组测定条件下,标准物质测定结果均在标准值不确定度范围内。其中,429.0 nm波长GF-AAS法测定结果相对其他3组显著偏低(P<0.05);ICP-MS法在检出限、定量限方面优于GF-AAS法;GF-AAS法测定结果357.9 nm波长优于429.0 nm波长。