Assessment Of Measurement Uncertainty Research Articles

Scatterometric defect measurements – uncertainty assessment by means of a virtual instrument and a statistical analysis

Defects in nanostructured surfaces have to be detected in or close to the manufacturing process in the production environment. For this purpose, scatterometry promises a non-contact approach with in-process capability. However, the achievable measurement uncertainty with a scatterometric measurement principle is difficult to assess by means of experiments. Especially for nano-surfaces with stochastic features, a large sample size is required. In addition, the influence of the natural uncertainty due to the inherent surface stochastics, which causes an ultimate uncertainty limit, remains hidden. Therefore, a virtual experimentation in combination with a statistical evaluation is proposed for the uncertainty assessment of scatterometric defect measurements of nanostructured surface. One virtual experiment calculates the scattered light distribution from a randomized modelled surface. For the uncertainty assessment, (a) multiple defective surfaces with the same defect grade are modelled, (b) the surfaces’ scattered light distributions are simulated, (c) the signal processing is applied for obtaining the virtual measurement results of the defect grade, and (d) the uncertainty is determined. The proposed virtual method is realized and demonstrated for defective ZnO nanograss surfaces, where the vacancy of nanograss is the studied defect as an example. As central results for the exemplarily studied defect grade measurement, the determined achievable mean uncertainty due to the nanostructure randomness is 3.2%, and the effect of the detector shot noise is negligibly small. Furthermore, the proposed method is universally applicable for any type of nanostructure/defect, and for any scatterometric principle, to clarify the respective potential for the reliable detection of nanostructure defects.

Using analytical performance specifications in a medical laboratory.

Analytical performance specifications (APS) are used for the quantitative assessment of assay analytical performance, with the aim of providing information appropriate for clinical care of patients. One of the major locations where APS are used is in the routine clinical laboratory. These may be used to assess and monitor assays in a range of settings including method selection, method verification or validation, external quality assurance, internal quality control and assessment of measurement uncertainty. The aspects of assays that may be assessed include imprecision, bias, selectivity, sample type, analyte stability and interferences. This paper reviews the practical use of APS in a routine clinical laboratory, using the laboratory I supervise as an example.

Comparative Study on Selected Insulating Materials for Industrial Piping.

This paper describes the results of an experimental assessment of the thermal conductivity of pipe insulation. The need for reducing energy loss in industrial piping systems makes the availability of relevant and reliable insulation materials of special importance. Several specimens of pipe laggings, made of different materials, including mineral wool, polyethylene foam (PEF), expanded polystyrene (EPS), flexible elastomeric foam (FEF) and polyurethane foam (PUR), were tested in accordance with the European standard ISO 8497. The thermal conductivity of the materials was measured for a wide range of temperatures. The results were compared with the values reported in the technical specifications as well as with the literature data. The assessment of measurement uncertainty was also described. The results showed that, in a few cases, thermal conductivity turned out to be greater than that declared by the manufacturer by as much as over 10%.

Application-oriented meta-model of measurement uncertainty

This article is aimed at enhancing the meta-model of measurement, proposed by the author in 2013, in a way as to emphasise the qualitative and quantitative aspects of the assessment of measurement uncertainty. With regard to the qualitative aspect, the concept of fundamental epistemic uncertainty is interpreted from a point of view of scientific instrumentalism. With regard to the quantification of measurement uncertainty, a methodology based on comparing two mathematical models is presented and illustrated with three examples of practical importance.

Teaching and assessment of physics measurement uncertainty in remote delivery during Covid-19 Lockdown

The teaching and assessment of measurement uncertainty in physics lab class has been an ongoing challenge under the Covid-19 no-access policy, especially in a Two-year community college setting with less budget. The tactile experience as a tacit knowledge must be delivered in words and students are presumed to be able to learn from reading and following the rules in a simulation, with an analogy of the learning of emotions in a literature class with the original words in the novel and the related movies. The transference learning process offers guidance to design the remote delivery of experiential learning in a lab class. The quantitative uncertainty in physics lab is an assessment of how well we know. The misconception that a simulation lab would carry zero uncertainty was found to be the more difficult for students to eliminate. When the teaching of uncertainty percent calculation be classified as a lesson at the average difficulty level, then the teaching of the uncertainty in graphical representation would be deemed to be at the next difficulty level. For the case with a single formula in several variables, the small change concept in algebra can be used to estimate the uncertainty when the small changes are in absolute magnitudes. For the case with two or more cascade formulas, the use of simulation to estimate uncertainty from the variation of the simulation results would be practical. Teaching uncertainty examples and assessment rubric examples for experiential learning in remote delivery during Covid -19 pandemic are discussed.

CT-Based Dimensional Metrology for Quality Assessment of the Internal Structure of Additive Manufactured Aluminum Parts

Two common types of internal defects of additively manufactured (AM) samples are lack-of-fusion and gas-entrapped porosities. These internal defects can have different physical origins and particular local characteristics (e.g., different shape, size). Thus, the use of reliable non-destructive inspection techniques is essential for the accurate assessment of integrity, allowing the applicable AM processing parameters correction. To overcome this challenge, this work aims to evaluate the accuracy of volumetric characteristics measured by computed tomography for porosity evaluations in AM samples, including assessment of measurement uncertainty. The effect of different cumulative thickness on the evaluated measurements accuracy is also assessed. The results show that deviations of defect size measurements can be below 2% if the proposed procedure is followed. In addition, the expanded uncertainty can be up to 10% of the measured magnitude when the cumulative thickness is increased to 70 mm. The physical relationships obtained between the cumulative thickness and the individual measurements are also presented.

Survey of physics reasoning on uncertainty concepts in experiments: An assessment of measurement uncertainty for introductory physics labs

Survey of physics reasoning on uncertainty concepts in experiments: An assessment of measurement uncertainty for introductory physics labs

On thresholds for controlling negative particle (PM2.5) readings in air quality reporting

Ambient PM2.5 (particles less than 2.5 μm in diameter) is monitored in many countries including Australia. Occasionally PM2.5 instruments may report negative measurements, although in realty the ambient air can never contain negative amounts of particles. Some negative readings are caused by instrument faults or procedural errors, thus can be simply invalidated from air quality reporting. There are occasions, however, when negative readings occur due to other factors including technological or procedural limitations. Treatment of such negative data requires consideration of factors such as measurement uncertainty, instrument noise and risk for significant bias in air quality reporting. There is very limited documentation on handling negative PM2.5 data in the literature. This paper demonstrates how a threshold is determined for controlling negative hourly PM2.5 readings in the New South Wales (NSW) air quality data system. The investigation involved a review of thresholds used in different data systems and an assessment of instrument measurement uncertainties, zero air test data and impacts on key reporting statistics when applying different thresholds to historical datasets. The results show that a threshold of −10.0 μg/m3 appears optimal for controlling negative PM2.5 data in public reporting. This choice is consistent with the measurement uncertainty estimates and the zero air test data statistics calculated for the NSW Air Quality Monitoring Network, and is expected not to have significant impacts on key compliance reporting statistics such as data availability and annual average pollution levels. The analysis can be useful for air quality monitoring in other Australian jurisdictions or wider context.

SUBSTANTIATION OF THE UNIVERSAL ADAPTIVE TECHNOLOGICAL SYSTEM OF COMPLEX LABORATORIES FOR QUALITY AND SAFETY ASSESSING OF GRAIN AND OIL CROPS

The materials of the article provide data on the export of domestic grain, oil crops and their processing products, the commodity structure of the export of domestic agricultural products and a dozen export countries during the operation of the grain corridor from March 2022 to August 2023. The main requirements for modern laboratories and their functions are listed. The components of a comprehensive analytical approach to assessing the quality and safety of grains and oilseeds according to modern international requirements are presented. It has been established that, in addition to the technical and economic component, the activities of complex laboratories are affected by a large number of technological limitations, among which an important place is occupied by the problems of quality control of test results. Today, the functioning of native laboratories that assess the quality and safety of grains and oilseeds has some of shortcomings that may affect the effectiveness of testing activities. In particular, there is a lack of a unified approach to addressing systemic requirements, a large number of regulators, conflicting requirements, and limited international harmonization. The requirements of industry regulations and contract specifications pose challenges for laboratories. All of this emphasizes need to develop a universal adaptive technological system for quality control of integrated laboratories for assessing the quality and safety of grains and oilseeds. The main components of quality management of laboratories for quality assessment of grains and oilseeds are considered and analyzed. It was found that only 11% of accredited domestic laboratories can comprehensively meet the current demand for conformity assessment services for agricultural raw materials. Based on the analysis, a roadmap of quality management components of laboratories for quality assessment of grains and oilseeds was developed. The development of such guidelines will help to meet diverse requirements and systematically demonstrate competence in line with current needs. Processes such as analytical method validation, measurement uncertainty assessment, metrological traceability, and accreditation support require significant financial investments. The creation and implementation of a universal adaptive technological system will help to rationalize the use of resources, thanks to logistical advantages, efficiency, reliability of results, and vertical management system. The creation and implementation of a universal adaptive technological system will help to rationalize the use of resources, thanks to logistical advantages, efficiency, reliability of results, and vertical management system.

THE IMPORTANCE OF UNCERTAINTY DETERMINATION DURING TECHNOLOGICAL TEMPERATURE MEASUREMENTS

As we know, one of the trends in the development of metrological control activities of enterprises and organizations is the calibration of measuring instruments through the assessment of measurement uncertainty. This process is an important factor to increase the accuracy of measurements, ensuring product quality, minimize the amount of waste products and increase the competitiveness of the organization. Such a parameter can be, for example, the standard deviation (mean squared error of the measurement results) or a number that is exactly divisible by it, or the width of the confidence interval. Measurement uncertainty combines several components. Some of these components can be estimated based on the statistical distribution of the results of a series of observations and characterized by their standard deviations. Considering that more than 50% of the measurements performed during technological processes are covered by temperature measurements, then we can say that the errors occurring during temperature measurements directly affect the quality of the product significantly. In the conducted research, the uncertainty in the temperature measurements performed during the technological processes was determined and the importance of determining this uncertainty was analyzed. Keywords: Metrological assurance, temperature measurements, technological process, statistical distribution, thermodynamics, uncertainty, metrology, accuracy, error, calibration.

An experimental study on capacitive and ultrasonic measurement principles and uncertainty assessment in laboratory wave measurements

Many studies in ocean engineering and related fields need physical wave modelling in controlled environments. Monitoring the free surface elevation over time is essential to forming accurate waves. Various wave height measurement instruments can be used to determine the free surface elevation. However, measurements based on only one principle might lead to uncertain results. This study aims to compare measurements taken with capacitance-type and ultrasonic-type wave height gauges for the same wave models and analyze uncertainty in wave modelling. Nine different wave cases were tested using three-wave heights and three-wave frequencies. In a two-dimensional wave flume, the amplitude and frequency of the waves were controlled with a mechanical wave generator. The Guide on the Expression of Uncertainty in Measurement (GUM) presented by the Joint Committee for Guides in Metrology (JCGM) was used following ITTC procedures and guidelines. The processes for acquiring data, selecting data intervals, estimating amplitude and frequency, and analyzing uncertainty are presented and discussed. The measurements by the ultrasonic-type wave height gauge required a different input stroke for the wave generator and had more uncertainties associated with the amplitude of the measured waves. The findings highlight that identifying differences in measurement principles is significant for wave modelling.

Determination of Melamine Uncertainty Assessment in Frozen Drinks

The uncertainty assessment of melamine in frozen drinks by high-performance liquid chromatography, According to the basic methods and procedures stipulated in the Assessment and presentation of Measurement Uncertainties and the Guidelines for the Assessment of Uncertainty in Chemical Analysis, The main sources of influence uncertainty were analyzed, and the assessment method for determining melamine uncertainty in frozen drinks was established. The results show that the results of (0.661 mg/kg ± 0.03, <i>k</i>=2) affect the determination of melamine uncertainty in frozen drinks, Uncertainty introduced by the fitted curve, the standard curve preparation process, the measurement repeatability, the Sample volume, the standard purity, Standard weighing and the sample amount. The model provides a reference for the uncertainty assessment of melamine in frozen drinks According to it, At the same time, in the daily detection and weighing, the measurement activities can be used to control the fitting curve and the standard solution preparation process, in order to reduce the measurement uncertainty, improve the accuracy of the test results, the compliance of the measurement results is important.

Estimation of Measurement Uncertainty of the Real-Time Location System (RTLS) with Ultra-Wideband (UWB) Technology

The need to control the real-time location of assets is increasingly relevant worldwide. The Ultra-wideband (UWB) technology is an IoT solution for real-time locating systems (RTLS). The location of the asset is obtained by the signal exchange between a wireless tag (asset) and fixed anchors. The tag interacts with the fixed anchors, defining its position through the distances obtained by trilateration. This data is sent to the server through the gateway. It is well-known that this process has several sources of errors. However, the measurement uncertainty assessment of UWB technology is an important topic regarding its scope of use. This paper presents a task-specific measurement uncertainty evaluation for the UWB positioning system, according to the ISO GUM. It aims to propose a method to support decision-making regarding the possible uses of UWB technology. The position provided by the UWB is compared with reference points using Cartesian coordinates that are measured with a total station, providing metrological reliability. Using the information from the estimated uncertainty, one can define the minimum tolerance interval associated with UWB technology for a given use. A case study demonstrates the method.

Uncertainty Assessment of Wave Elevation Field Measurement Using a Depth Camera

The present study suggests a methodology for acquiring wave elevation fields using a depth camera sensor, with assessment results for the test uncertainty. The depth camera module of an Azure Kinect is calibrated using marker arrays on the optic table, to obtain a polynomial mapping function between the pixel-wise and physical position. For installation of the depth camera in a wave channel, the system is aligned using the built-in inertial measurement unit of Azure Kinect to be perpendicular to the calm water surface. The systematic and random standard uncertainties were evaluated from the analysis of calibration and repeated tests, respectively. The wave height measurement results for the depth camera were compared to those for the capacitance-type and ultrasonic wave height gauges. The test uncertainty of the depth camera increased in large wave stiffness conditions, where the time-of-flight sensor has a disadvantage in measurement.

Visualizing Uncertainty to Promote Clinicians' Understanding of Measurement Error.

Measurement error is an inherent part of any test score. This uncertainty is generally communicated in ways that can be difficult to understand for clinical practitioners. In this empirical study, we evaluate the impact of several communication formats on the interpretation of measurement accuracy and its influence on the decision-making process in clinical practice. We provided 230 clinical practitioners with score reports in five formats: textual, error bar, violin plot, diamond plot, and quantile dot plot. We found that quantile dot plots significantly increased accuracy in the assessment of measurement uncertainty compared with other formats. However, a direct relation between visualization format and decision quality could not be found. Although traditional confidence intervals and error bars were favored by many participants due to their familiarity, responses revealed several misconceptions that make the suitability of these formats for communicating uncertainty questionable. Our results indicate that new visualization formats can successfully reduce errors in interpretation.

Software for measurement uncertainty assessment and actual metrological characteristics of viscometers

The issue of implementation of software for rapid assessment of uncertainty of metrological control results of measuring instruments used in the field of state metrological control and supervision in calibration and evaluation of actual metrological characteristics of operating viscosimeters was considered. An interpretation of the application of the EXCEL program and other software for the special methodology for automating uncertainty calculations developed by us was carried out, which significantly simplified the work and reduced the time spent by specialists in the metrological laboratory. Basic requirements of comparison of software for calculation, calculation and estimation of uncertainty in the realm of mathematical models of validated techniques are determined. The experimental results of the comparative analysis taking into account the set tasks are presented, the most common and effective universal software for calculating the uncertainty of the results of the experiment. The object of the study is universal software for estimating the uncertainty of measurements and other metrological characteristics of viscometers, structured by types of measurements, in the graphic programming environment. The software can be used both in laboratories and in industrial premises. The workplace can be both a metrological laboratory, the working area of which is a table with instruments, and a production room. As a rule, accredited laboratories do not have a special staff of metrologists or specialists who perfectly understand the basics of mathematical statistics and the concept of measurement uncertainty. The complexity and necessary amounts of calculations that are carried out in assessing the uncertainty of measurements require significant laboratory resources.

A practical approach example to measurement uncertainty: Evaluation of 26 immunoassay parameters.

IntroductionMeasurement uncertainty is a non-negative parameter that characterizes the distribution of all values appropriate to the measured size and is associated with the measured result. In this study, we aimed to compare the results with various suggestions and produce more qualified results by calculating the measurement uncertainties of the immunoassays like fertility hormones, drug concentration tests, cardiac markers, thyroid function tests and tumour markers.Materials and methodsUncertainty calculation was made in accordance with the top-down approach according to Nordtest guide. The 12-month study of internal and external quality assessment results were used. The parameters of drug concentration tests were performed on the Abbott Architect c8000, other hormones/markers on the i2000 of the same brand.ResultsFactors that increased the measurement uncertainty of a test were due to external quality control data. The calculations showed that 13 of 26 parameters satisfied quality requirements. The highest uncertainty value, with 28% belonged to cancer antigen 19-9 test. The lowest value was calculated for prolactin with 8.3%. Dehydroepiandrosterone sulfate and phenytoin performed poorly in terms of measurement uncertainty, although internal and external quality control assessment results were considered favourable for both.ConclusionIt is recommended that the concept of measurement uncertainty, which plays an important role in the total quality performance of the laboratory, should be followed up by the clinical laboratory experts at certain time intervals and should be increased the awareness of clinicians about the subject.

Uncertainty Assessment of Differential Absorption Lidar Measurements of Industrial Emissions Concentrations

Differential absorption lidar (DIAL) has been shown to be a very effective technique for the location and quantification of emissions of pollutants and greenhouse gases at industrial facilities. Several field trials have demonstrated the DIAL system performances and contributed to the development of the DIAL methodology, which is the basis of the protocols described in the European Standard EN 17628. While numerous papers have focused on different aspects of DIAL uncertainties, a rigorous propagation of the uncertainties in the DIAL equation has not been found. In this study, all the uncertainty sources contributing to a DIAL concentration measurement are assessed and the impact they have on the calculation of the mass emission rate. We derive the equations for both a DIAL system path-concentration integral and concentration uncertainties. The results from a methane measurement are presented, showing that for a signal to noise ratio on the backscattered lidar signals of 500, the path-concentration integral standard uncertainty is 2.3 ppb km and the concentration standard uncertainty is 92 ppb over a sampling spacing of 45 m. An equation is also presented enabling calculation of the contribution of the concentration uncertainty to the mass emission rate uncertainty.

To the Editor.

To the Editor: We read with interest the article by Tababa et al1 describing differences between recommended surgical margins and measured histological margins in melanoma. In the discussion, they do mention in passing that among other factors, discordance between histologic and surgical margins may be due to differences in interpretation of histological margins between pathologists. We would like to highlight the importance of measurement uncertainty in histopathologic margin measurement. There are no measurements, especially in medicine, which are exact—every laboratory measurement, whether it is sodium measured in plasma, the number of white cells in a smear, Breslow depth,2 or histological measurement to margins has some degree of error. In clinical chemistry and laboratory medicine, measurement uncertainty assessment is required in accordance with ISO 17025 and ISO 151893 but seems often ignored in anatomical pathology measurements. For example, we have recently shown that there is measurement uncertainty in measuring margins for basal cell carcinoma and that this uncertainty is dependent on pathologist factors such as which pathologist measures the margins and specimen factors, for example, which actual cross-section is being examined.4 The different methods used to measure margins, for example, graticule, stage micrometer, or eyepiece field diameter may also contribute to error. We have no reason to believe that melanoma margin assessment would be any different. Melanoma margins, especially the in situ component, are more complicated by the fact that there is often debate about what is the “last”' malignant cell and that this assessment could potentially bring about a large variation in assessed margins. We note that 2 different dermatopathologists measured the margins in this study, but no estimates of measurement uncertainty (including differences between pathologist measurements of the same slide) were made. In addition, the number quoted in the current article for specimen shrinkage (15%) seems not to be an absolute number but a range. In the report referenced, the actual range for width change after immersion in formalin was 18.75% (indicating expansion) to 37.50%,5 again adding to the uncertainty of the real histological margins. In summary, it is difficult to interpret the measurement made by 1 pathologist, and how close to the margin it actually is in truth, and how this relates statistically to the clinical (surgical) measurement. It behoves pathologists in any laboratory specialty to appreciate that no measurement is exact, including histologic measurements. Measures of uncertainty should be established for appropriate interpretation of histopathologic margin measurements and included in studies such as the current one.

Measurement uncertainty assessment for potentiometric determination of trace anionic impurities in graphite post ultrasonic extraction: A bottom-up approach

Measurement uncertainty assessment for potentiometric determination of trace anionic impurities in graphite post ultrasonic extraction: A bottom-up approach