Comparison of uncertainty estimates in international metrological and ecological guides

Comparisons have been made on the international ecological guidelines CORINAIR, IPCC, and the GHG Protocol, which implement evaluation of the uncertainties in pollution discharges to the atmosphere, greenhouse gases, and metrological guidelines on estimating the uncertainty of GUM measurements. The main sources of uncertainty are identified and their values are estimated together with their contribution to the general uncertainty in the estimation of greenhouse gas discharges. __________ Translated from Izmeritel’naya Tekhnika, No. 5, pp. 22–26, May, 2007.     

Methods of estimating hydraulic and transport parameters for the unsaturated zone

Methods of estimating hydraulic and transport parameters for the unsaturated zone are presented. Two approaches to parameter estimation are discussed. The first approach is based on inversion of the governing initial-boundary value problem for unsaturated flow and/or transport using data from transient experiments. The second approach utilizes particle size distribution data to obtain estimates of soil hydraulic properties. Example applications of the two different approaches are presented and their advantages and limitations are discussed. Procedures for identifying and quantifying sources of uncertainty in parameter estimates are examined. Ongoing research on the scale-up of parameters for applications in large-scale numerical simulations is reviewed. Financial support for this study was provided by the Electrical Power Research Institute (Contract RP2485-06), and by the American Petroleum Institute (Contract WM-5-324-7).     

扩展不确定度中包含因子的确定方法

通过分析被测量可能值的概率分布,给出展伸不确定度包含因子的确定方法,并对有效自由度的非整数值所对应的包含因子的取值进行了详细的研究.采用不同的插值函数研究了有效自由度小于5的情况,得到较为准确的结果.     

A comparison of different approaches to estimating measurement uncertainty

The inadmissibility of certain assumptions used in the procedures of the Guide to the Expression of Uncertainty in Measurement and the draft of Supplement 1 to it, which lead to an additional complication of the procedures for estimating uncertainty, which is particularly important for the approach in Supplement 1, is demonstrated. An approach based on the use of a statistical model enables these difficulties to be removed and ensures the required estimation accuracy. __________ Translated from Izmeritel’naya Tekhnika, No. 3, pp. 6–9, March, 2008.     

Multivariate receptor models and model uncertainty

Estimation of the number of major pollution sources, the source composition profiles, and the source contributions are the main interests in multivariate receptor modeling. Due to lack of identifiability of the receptor model, however, the estimation cannot be done without some additional assumptions.

A common approach to this problem is to estimate the number of sources, q, at the first stage, and then estimate source profiles and contributions at the second stage, given additional constraints (identifiability conditions) to prevent source rotation/transformation and the assumption that the q-source model is correct. These assumptions on the parameters (the number of sources and identifiability conditions) are the main source of model uncertainty in multivariate receptor modeling.

In this paper, we suggest a Bayesian approach to deal with model uncertainties in multivariate receptor models by using Markov chain Monte Carlo (MCMC) schemes. Specifically, we suggest a method which can simultaneously estimate parameters (compositions and contributions), parameter uncertainties, and model uncertainties (number of sources and identifiability conditions). Simulation results and an application to air pollution data are presented.     

Quantification of margins and uncertainties of complex systems in the presence of aleatoric and epistemic uncertainty

Performance assessment of complex systems is ideally done through full system-level testing which is seldom available for high consequence systems. Further, a reality of engineering practice is that some features of system behavior are not known from experimental data, but from expert assessment, only. On the other hand, individual component data, which are part of the full system are more readily available. The lack of system level data and the complexity of the system lead to a need to build computational models of a system in a hierarchical or building block approach (from simple components to the full system). The models are then used for performance prediction in lieu of experiments, to estimate the confidence in the performance of these systems. Central to this are the need to quantify the uncertainties present in the system and to compare the system response to an expected performance measure. This is the basic idea behind Quantification of Margins and Uncertainties (QMU). QMU is applied in decision making—there are many uncertainties caused by inherent variability (aleatoric) in materials, configurations, environments, etc., and lack of information (epistemic) in models for deterministic and random variables that influence system behavior and performance. This paper proposes a methodology to quantify margins and uncertainty in the presence of both aleatoric and epistemic uncertainty. It presents a framework based on Bayes networks to use available data at multiple levels of complexity (i.e. components, subsystem, etc.) and demonstrates a method to incorporate epistemic uncertainty given in terms of intervals on a model parameter.     

Introducing measurement uncertainty into methods of calibrating and checking measuring instruments

The letter discusses certain aspects of introducing the Guide to the Expression of Uncertainty in Measurement, and the draft of Supplement 1 to this Guide for evaluating calibration results. __________ Translated from Izmeritel’naya Tekhnika, No. 3, pp. 70–72, March, 2008.     

Some aspects of the uncertainty of a measured quantity and the uncertainty of measurements in thermometry

The use of the main concepts of the international document Guide to the Expression of Uncertainty in Measurement to estimate the uncertainty of temperature measurements is considered. Particular attention is devoted to the sequence of analyzing the accuracy of measurements: a clear definition of the measured quantity and an analysis of the method of measurement used and of the accuracy of the instruments employed for a correct and complete determination of the components of type B uncertainty. Examples of the estimation of the uncertainty of temperature measurements for standard and working measuring instruments are presented.Translated from Izmeritelnaya Tekhnika, No. 9, pp. 38–41, September, 2004.     

基于不确定度的精密测量结果的处理

从正确处理精密测量结果的角度出发，通过精密测量实例，分析了采用测量不确定度处理精密测量结果的方法，讨论了采用测量不确定度处理精密测量结果的意义。     

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。     

100ml容量瓶容量测量结果的不确定度评定

主要叙述了在100ml容量瓶的检定过程中,对其容量测量结果的不确定度的评定     

空气比释动能率测量不确定度评定

文章主要论述工业X射线探伤机空气比释动能率测量不确定度的评定，并详细分析了空气比释动能率不确定度的来源、标准不确定度分量的评定及自由度的计算等。     

一种新的近空间GPS信号多路径估计方法

结合GPS多路径信号模型及其相关函数的特点，在研究基于TK（Teager-Kaiser）算子的近空间多路径估计算法的基础上，提出了一种新的更为简洁的GPS信号近空间的多路径估计算法，并通过仿真验证了算法的有效性。仿真结果表明，该算法能以高分辨率准确地估计GPS信号近空间的多路径模型。     

Modern and appropriate technologies for the reduction of gaseous pollutants and their effects on the environment

Harmful effects on environment such as global warming and climate change may result from the gases emanating from fossil fuel combustion. Jordan and most Middle East countries use fossil fuels exclusively. Therefore, new technologies which could accommodate the demand for cleaner effluents, such as: combined cycles, fluidized bed combustion, magneto hydrodynamics, fuel cells, nuclear power, natural gas, renewable energy, and energy conservation have been considered. CO₂ being the most produced gas, many technical methods of reducing and reusing CO₂ have been suggested such as: Injection in oceans, storage in caverns, injection in depleted oil and gas fields, pumping during oil recovery, storage as CO₂ ice, elimination by fixation using water algae, and increasing plantation especially forestation. These methods are being used at different degrees in the Middle East countries. Reduction of formation and harmful effects of other gaseous pollutants is also discussed, with some concentration on the transportation sector, energy efficiency and fuel cells, which have special importance for the developing countries.     

分布传播及其在不确定度中的应用

论述分布传播,研究了分布传播分析,讨论了不确定度的分布传播,最后用实例说明了它在不确定度中的应用.     

智能变送器示值误差测量不确定度的评定

介绍用744过程仪表认证校准器检定智能变送器时,以国家计量技术规范JJF1059-1999《测量不确定度评定与表示》为依据,讨论了测量不确定度的几个主要来源。对智能变送器示值误差的测量不确定度进行了全面的分析评定。从而也为实验室检定、校准时选择合适的标准仪器提供依据。     

计量卧式罐容量的测量结果不确定度评定

文章对对接式半椭球顶卧式金属油罐测量结果不确定度进行了详细的分析和评定，评定方法符合JJFl059-1999和JJF1033-2001国家计量技术规范的要求。     

Quantification of margins and uncertainties: Alternative representations of epistemic uncertainty

In 2001, the National Nuclear Security Administration of the U.S. Department of Energy in conjunction with the national security laboratories (i.e., Los Alamos National Laboratory, Lawrence Livermore National Laboratory and Sandia National Laboratories) initiated development of a process designated Quantification of Margins and Uncertainties (QMU) for the use of risk assessment methodologies in the certification of the reliability and safety of the nation's nuclear weapons stockpile. A previous presentation, “Quantification of Margins and Uncertainties: Conceptual and Computational Basis,” describes the basic ideas that underlie QMU and illustrates these ideas with two notional examples that employ probability for the representation of aleatory and epistemic uncertainty. The current presentation introduces and illustrates the use of interval analysis, possibility theory and evidence theory as alternatives to the use of probability theory for the representation of epistemic uncertainty in QMU-type analyses. The following topics are considered: the mathematical structure of alternative representations of uncertainty, alternative representations of epistemic uncertainty in QMU analyses involving only epistemic uncertainty, and alternative representations of epistemic uncertainty in QMU analyses involving a separation of aleatory and epistemic uncertainty. Analyses involving interval analysis, possibility theory and evidence theory are illustrated with the same two notional examples used in the presentation indicated above to illustrate the use of probability to represent aleatory and epistemic uncertainty in QMU analyses.     

扩展不确定度分析与评定

ISO《测量不确定度表示指南》给出两种选择包含因子的方法 :韦尔奇 -萨特思韦特公式法和简便方法 .文章据此对扩展不确定度的影响因素进行分析 ,并针对使用简便方法引起的包含因子的误差、不确定度以及扩展不确定度的不确定度进行分析和评定 ,以阐明有效自由度对包含因子和扩展不确定度的影响     

Volcanism and the atmosphere: the potential role of the atmosphere in unlocking the reactivity of volcanic emissions

Recent measurements of reactive trace gas species in volcanic plumes have offered intriguing hints at the chemistry occurring in the hot environment at volcanic vents. This has led to the recognition that volcanic vents should be regarded not only as passive sources of volcanic gases to the atmosphere, but also as 'reaction vessels' that unlock otherwise inert volcanic and atmospheric gas species. The atypical conditions created by the mixing of ambient atmosphere with the hot gases emitted from magma give rise to elevated concentrations of otherwise unexpected chemical compounds. Rapid cooling of this mixture allows these species to persist into the environment, with important consequences for gas plume chemistry and impacts. This paper discusses some examples of the implications of these high-temperature interactions in terms of nitrogen, halogen and sulphur chemistry, and their consequences in terms of the global fixed nitrogen budget, volcanically induced ozone destruction and particle fluxes to the atmosphere. Volcanically initiated atmospheric chemistry was likely to have been particularly important before biological (and latterly anthropogenic) processes started to dominate many geochemical cycles, with important consequences in terms of the evolution of the nitrogen cycle and the role of particles in modulating the Earth's climate.