交流数字功率表测量不确定度的评定

交流数字功率表作为多用途电子测量仪器,在物理、电气、电子等测量领域得到广泛的应用,如何提高功率表校准的准确度是功率表应用的重要课题之一。本文通过对功率表的校准,对其测量结果进行不确定度评定。     

不确定度A类评定及不确定度B类评定的探讨

本文对不确定度A类评定及不确定度B类评定进行了分析.     

平板工作面平面度测量不确定度评定

本文阐述了用分度值为0.01mm/m的电子水平仪进行平板平面度测量的不确定度分析。     

测量结果不确定度评定技巧

测量结果的不确定度评定应用越来越广泛了,在校准与测量完成后,均需给出测量结果的不确定度。但很多时候,测量结果不确定度保持不变,究其原因,虽然大家明白每次都应重新计算,但因计算繁琐,计算数据太多太烦。基于此,在此介绍一种简单可行的测量结果不确定度评定技巧,可迅速解决此问题。     

钢筋抗拉强度测量结果的不确定度评定

用微机控制电液伺服式万能试验机测量钢筋的抗拉强度时,为确定测量结果的分散性即测量结果的置信区间,对影响检测结果的诸多因素进行分析,确定不确定度产生的来源,并采用A类不确定度评定和B类不确定度评定的方法,对各个不确定度分量进行评定,再根据各个量的方差和协方差算得合成标准不确定度,最终用扩展不确定表示,给出钢筋抗拉强度测量的不确定度报告。     

数字电容表校准值的不确定度评定

本文介绍了数字式电容表的校准方法,分析了校准过程中的不确定度来源,并对校准结果进行了不确定度评定。     

数字温湿度计测得值的测量不确定度评定

本文介绍了数字温湿度计测得值的不确定度评定方法。     

输入估计值的测量不确定度评定

本文所介绍的与1993年由ISO等7个国际组织联合发表的《测量不确定表示指南》（简称《指南》）完全一致，只是指南上的实用于物理测量的绝大多数领域，而本文介绍的仅适用于校准实验的测量。同时本文主要侧重于对输入估计值的A类测量不确定度和B类测量不确定度的评定的介绍，为输出估计值的测量不确定度评定奠定了良好的基础。     

不确定度评定实例分析 耐电压测试仪测量结果的不确定度评定

耐电压测试仪作为对各种电气设备、绝缘材料和绝缘结构等的抗电性能进行检测和试验的仪器,其使用已相当普遍.因此,对其在使用过程中的两个主要参数--输出电压值及击穿报警电流的测量结果不确定度进行评定非常必要.     

电能表检定装置测量不确定度评定分析

通过对电能表校验装置不确定度的分析与计算,来理解不确定度评定方法。     

一种质粒DNA标准物质的定值数据统计及不确定度评定

为研制一种质粒DNA标准物质,应用紫外分光光度法(UV)和高分辨电感耦合等离子体质谱法(HR-ICPMS)对质粒DNA标准物质候选物的浓度进行测定,统计定值结果,并对测量的不确定度进行评定。最终,质粒DNA标准物质的浓度表示为(75.1±2.1)ng/μL(k=2)。     

电流互感器比值差测量结果的不确定度评定

以一体化互感器检定装置检定电流互感器为例，依据JJF1059—1999《测量不确定度评定与表示》规定，对标准电流互感器检定装置中电流互感器比值差测量结果不确定度进行了评定，并通过计算，指出了影响其测量结果不确定度的因素和来源。     

A mathematical model for vehicle routing problem under endogenous uncertainty

In this study, a multistage stochastic programming (SP) model is presented for a variant of single-vehicle routing problem with stochastic demands from a dynamic viewpoint. It is assumed that the actual demand of a customer becomes known only when the customer is visited. This problem falls into the category of SP with endogenous uncertainty and hence, the scenario tree is decision-dependent. Therefore, nonanticipativity of decisions is ensured by conditional constraints making up a large portion of total constraints. Thus, a novel approach is proposed that considerably reduces the problem size without any effect on the solution space. Computational results on some test problems are reported.     

Data quality and uncertainty assessment methodology for pavement LCA

In performing pavement life cycle assessment (LCA), users are facing various reports of energy intensity coefficient (EIC) of pavement materials which differ considerably among data sources and therefore alter the LCA results significantly. Instead of selecting a certain EIC without or of little explanation for the current pavement LCA practices, this study proposed a methodology to build probability density function (PDF) for EIC based on available data-set and their qualities. Each data was first evaluated about the data quality indicator (DQI) through data quality pedigree matrix and converted to PDF in modified Beta distribution form. Three weighting methods, the DQI one, coefficient of variation (COV) one and analytical hierarchy process (AHP) one, were developed to assign weightings for different data. Monte Carlo simulation was run with the weighted PDF of each data as input to obtain the ultimate PDF for EIC. A case study to estimate the bitumen’s EIC with eight data samples were performed using the proposed methodology. It is found (1): the estimates by the proposed methodology is of higher reliability (lower COV) compared to any single data due to utilisation of information of the overall data samples; (2) the AHP weighting method is most favoured despite the results of the three weighting methods are close; (3) the central estimates of bitumen’s EIC are between5.4~5.8 MJ/kg. The proposed methodology is helpful in aiding calculating EICs for pavement materials and capturing uncertainties in LCA results in a statistical sense.     

Framework for sensitivity and uncertainty quantification in the flutter assessment of bridges

The phenomenon of aerodynamic instability caused by wind is usually a major design criterion for long-span cable-supported bridges. If the wind speed exceeds the critical flutter speed of the bridge, this constitutes an Ultimate Limit State. The prediction of the flutter boundary therefore requires accurate and robust models. The state-of-the-art theory concerning determination of the flutter stability limit is presented. Usually bridge decks are bluff and therefore the aeroelastic forces under wind action have to be experimentally evaluated in wind tunnels or numerically computed through Computational Fluid Dynamics (CFD) simulations. The self-excited forces are modelled using aerodynamic derivatives obtained through CFD forced vibration simulations on a section model. The two-degree-of-freedom flutter limit is computed by solving the Eigenvalue problem.A probabilistic flutter analysis utilizing a meta-modelling technique is used to evaluate the effect of parameter uncertainty. A bridge section is numerically modelled in the CFD simulations. Here flutter derivatives are considered as random variables. A methodology for carrying out sensitivity analysis of the flutter phenomenon is developed. The sensitivity with respect to the uncertainty of flutter derivatives and structural parameters is considered by taking into account the probability distribution of the flutter limit. A significant influence on the flutter limit is found by including uncertainties of the flutter derivatives due to different interpretations of scatter in the CFD simulations. The results indicate that the proposed probabilistic flutter analysis provides extended information concerning the accuracy in the prediction of flutter limits.The final aim is to set up a method to estimate the flutter limit with probabilistic input parameters. Such a tool could be useful for bridge engineers at early design stages. This study shows the difficulties in this regard which have to be overcome but also highlights some interesting and promising results.     

轴承外径标准器测量的不确定度评定

不确定度评定在各行各业测量工作中十分重要 ,文章从应用的角度出发 ,着重论述不确定度的评定方法与计算过程及其在轴承外径标准器测量中的具体应用     

Democracy and the governance of uncertainty. The case of agricultural gene technologies

The use of genetically modified organisms (GMOs) in agriculture and food production is the object of an intense and divisive debate. Drawing on a study on the public perception of agricultural gene technologies carried out in five European countries, the article deals with the policy aspects of the issue, and more precisely on the relation between institutions, experts and the public in a context of deep uncertainty. A theoretical framework is developed and compared with the study findings, suggesting that issues like the GMOs one represent a strong case for a more participatory policy-making. My conclusions suggest a style of governance based on the principles of deliberative democracy, as a suitable approach to the confrontation of different viewpoints and forms of knowledge. This appears to be the best way to improve the overall quality of policy-making: in this I include its legitimacy, the degree of public trust, and also the actual quality of its products. Strengthening the role of the public sphere seems more effective than simply increasing direct decision-making by the populace, and it offers an alternative to the 'elitist' solutions to the crisis of representative democracy.     

如何评估回收率测量结果不确定度

加标回收率方法是测定复杂基体中待测物的重要而普遍适用的方法。然而,人们对回收率测量结果不确定度的评估和它对待测物测量结果不确定度评估中的贡献却关注较少。现就回收率测量结果不确定度评估及如何对待测物测量结果的修正进行讨论。     

Homogenization with uncertainty in Poisson ratio for polymers with rubber particles

The main aim of this work is dual computer analysis of probabilistic coefficients for the homogenized tensor of the polymer filled with the rubber particles having randomized Poisson ratios of both constituents. The major issue is to verify an influence of a randomness in rubber Poisson ratio close to the compressibility limit on the uncertainty of the effective tensor probabilistic characteristics. Probabilistic analysis presented here is carried out using mainly the stochastic perturbation technique provided by the common application of the traditional FEM commercial code ABAQUS and the symbolic computations package MAPLE. This FEM-based technique employs polynomial response function of the optimum order recovered from the weighted least squares method and following a set of deterministic solutions obtained for various values of the randomized input parameter. Optimization procedure is released entirely into a symbolic environment, where maximization of the correlation factor together with minimization of the fitting variance and approximation error are applied. Homogenization technique consists in equating of deformation energies for the real composite and the artificial one characterized by the effective elasticity tensor with uncertainty.     

Treatment of uncertainty in structural damage assessment

Structural damage assessment is a process that involves decision-making under uncertainty. Reasoning with or about uncertainty has been the focus of research in many fields in addition to civil engineering, such as decision analysis, philosophy, statistics and psychology. Several methods for the representation of reasoning under uncertainty have been developed. These methods, which the artificial intelligence community refers to as uncertain inference schemes, will be briefly discussed in this paper. One particular scheme, the causal network approach, will be examined in detail. Its application to post-earthquake damage assessment will be given. This particular application represents an approach that has not been used in the structural engineering field before.