Calculation Of Measurement Uncertainty Research Articles

Determination of Uncertainty in calibration of External Micrometer

In recent years there has been a growing awareness of measurement uncertainty, mainly for two reasons. First, the ever- increasing number of laboratory accreditations requires the evaluation of measurement uncertainty, especially in the area of calibration. Second, quality system protocols get mature with process and time. This is because manufacturers ensure the reliability of their measurements through correct calibration of their test and measuring equipment. International and national regulations require calibration and testing laboratories to provide result of measurement uncertainty. Calibration of the measuring instrument is the process in which the readings obtained from the instrument are compared with the standard values in the laboratory at several points along the scale of the instruments i.e. micrometer, gauges, calipers etc. In general, a calibration without information about the uncertainty of these estimates is incomplete. Calculating measurement uncertainty is an attempt to reasonably limit the results of measurements as referring to standard operating procedures. Since each measurement only provides a result of the outcome, the main requirement of the uncertainty estimation is to make reader confident that reading is within stated range. Proper calibration involves more than just estimating measurement uncertainty. It also requires that the estimated value is small compared to the stated accuracy of the meter

Evaluation of a laser speckle interferometry-based diagnostic system for wall surface variation in tokamak device

The realization of high-parameter, long-pulse operation of a tokamak inevitably faces a number of safety and operational constraints, which need to be achieved through comprehensive in-situ monitoring and control of the wall materials. Laser speckle interferometry (LSI) has been proposed to diagnose changes in the surface topography of wall materials. An LSI-based experimental system has been established and a quantitative evaluation process has made for it. The accuracy, range, and uncertainty of measurement are determined by measuring the topography change resulting from laser ablation and pulsed laser deposition. The calculation of measurement uncertainty considers various sources of error such as measurement noise, residual flatness, measurement errors, and measurement repeatability. This evaluation provides an overview of the measurement performance and reliability of the experimental system and helps to clarify the advantages and limitations of LSI for wall surfaces diagnosis. The evaluation can also serve as a useful reference for optimizing the LSI-based measurement system for better adaption to the EAST diagnostic conditions.

Agar diffusion microbiological assay measurement using a smartphone device and its measurement uncertainty using the bootstrapping method

Usually, inhibition zone sizes in agar diffusion microbiological assay of antibiotics are measured using regular callipers. In this study, we proposed the use of a smartphone app for measuring inhibition zone sizes. The smartphone app allows for standardized measurements with a reference scale, which provides measured values comparable to those obtained using regular callipers. The main uncertainty source associated with antibiotic potency is inhibition zone size variability. Here, we suggest using the bootstrapping method, a resampling technique, to estimate measurement uncertainty without complex calculations. This simplifies the process and yields comparable results to the usual measurement uncertainty calculations. Both improvements were successfully applied to determine the potency of gentamicin, linezolid, and cefazolin. The results showed that smartphone-based measurements and the bootstrapping approach are valuable tools in agar diffusion microbiological assays.

Cohran-Horwitz Method for Within-Lab Precision Acceptability in ISO 17025 Testing Laboratories

The issue of reliability of retesting data is a growing concern among testing laboratories. This document describes how to establish the acceptability of retesting of retained items during quality assurance, determining competence and measurement uncertainty calculations. Two methods are discussed and numerical examples are also given

Uncertainty model for automated gunshot residue particle length measurements obtained from electron microscopy images.

Currently, the use of algorithms and computer vision systems for metrological purposes has increased in different areas of knowledge to reduce human error and process deviations, consequently increasing reliability and reducing measurement uncertainties. This study presents a model for estimating the uncertainty of Feret's diameter (DF ) measurements of scanning electron microscopy (SEM) images from regular and irregular gunshot residue (GSR) particles at different magnifications. The data were extracted using the automatic measurement algorithm developed by the Brazilian Institute of Metrology, Quality and Technology (Inmetro). The proposed uncertainty model was based on the recommendations of the guide to the expression of uncertainty in measurement (GUM). The gold standard technique to identify and detect GSR particles is the SEM coupled to energy dispersive X-ray spectroscopy (SEM/EDS), which was used in the study. The low uncertainty values obtained in this study are justified by the refinement of the measurements performed at each stage of digital image procedures. The proposed uncertainty model contributes in an innovative way to the metrological evaluation of regular and irregular GSR particles at different images magnifications. The correct morphometry definition of these particles allows to study their distinction from other possible sources of GSR and, above all, their correlation with the type of ammunition used when firing the firearm. These measurement uncertainty calculations can be applied to any object images acquired by SEM, which provides more confidence in the results of measurements of the object of interest.

METROLOGICAL PROVISION OF WORKPLACE CERTIFICATION ACCORDING TO WORKING CONDITIONS

The purpose of the study is to determine the requirements for research methods, measurements with the help of FTA of harmful and dangerous production factors, which will allow to ensure a high level of attestation of workplaces according to working conditions. The task of the research includes consideration of issues related to ensuring the unity of measurements in the field of labor safety, compliance of metrological activity in the specified field with the requirements of current legislation in the field of metrology. The task of the research is also to identify problems related to the methodological support of laboratory research in the field of occupational safety, the absence of metrological requirements for laboratory research methods, metrological confirmation of FTAs, which are intended to perform workplace attestation. Currently, there are separate scientific works on the development of standard procedures for measuring dangerous or harmful factors of the production environment, there is an established norm for any harmful parameter, but there is no national order in the methodology of measuring each parameter. Individual measurement methods do not have the status of a normative legal act. Thus, at present, there are no legal acts regulating mandatory methods of measuring the parameters of harmful factors of the production environment and the labor process during workplace attestation. Analyzing regulatory documents, it can be concluded that from the main documents establishing the standardization of some factors of the working environment, the accuracy of measurements was established only for microclimate parameters. It should be concluded that in the field of labor protection, the state of ensuring the unity of measurements cannot be recognized as satisfactory. Summing up, we can come to the disappointing conclusion that for a reliable assessment of working conditions in workplaces, it is necessary to follow the methods of measurement and calculation of measurement uncertainty, which, unfortunately, are not always set out in mandatory documents. Keywords: harmful and dangerous factors, certification of the workplace, uncertainty of measurements, checking, verification.

CALCULATING THE UNCERTAINTY OF MULTI-FUNCTIONAL EQUIPMENT AND PREPARATION OF THE UNCERTAINTY BUDGET

Measuring uncertainty is not easy to calculate. Due to the large number of factors and parameters affecting the process during uncertainty assessment of complex objects, it is necessary to perform a correct assessment. In automated processes and automatically controlled systems, the factors affecting the measurement result are different. Engineers have trouble estimating uncertainty. Therefore, it is necessary to disclose an exclusive six-step process to calculate the measurement uncertainty and put together these instructions. Learn how to calculate measurement uncertainty in six easy-to-use steps. Also, what information is needed to calculate the uncertainty, how to obtain the uncertainty capability, and how to use calculations to obtain an overestimation or underestimation of the uncertainty. In addition, you can get some exclusive tips to help you calculate uncertainty like a pro with the help of the extract. Both production equipment and production systems can never be completely described or predicted. It is a contradiction for an engineer to get an accurate measurement and get the process right. Even if the engineer performs the measurement at a very high level, there will still be additional effects on the measurement result and the measurement process. Accordingly, this article can be used to estimate uncertainty. Keywords: Uncertainty, uncertainty calculation, distribution, budget, standard deviation, A and B type of uncertainty, expanded and combined uncertainty.

Bottom-up and top-down measurement uncertainty evaluation for multivariate spectrophotometric procedures

Multivariate spectrophotometric procedures are widely used in drug analysis to quantify one or more substances in a sample. Even if the analytical procedure is validated, there is always some degree of uncertainty related to the analytical results. No studies were found in the literature that evaluated the measurement uncertainty for multivariate spectrophotometric procedures. Thus, this paper aims to estimate the measurement uncertainty of the quantification of acetylsalicylic acid (ASA) and salicylic acid (SA), in an ASA samples, by a stability-indicating multivariate spectrophotometric procedure. The measurement uncertainties of ASA and SA were estimated by the top-down approach, using the Nordtest/ISO 11352 and VAM Project methodologies, and by the bottom-up approach, using the Monte Carlo method (MCM). The calculation of measurement uncertainty considered uncertainty sources related to the preparation of sample and standard solutions and the impact of these sources on the model obtained by partial least squares (PLS). The uncertainty of the spectra was estimated by bootstrap resampling method. The expanded uncertainties estimated for ASA were 3.7%, 4.1% and 3.7% calculated by MCM, Nordtest/ISO 11352 and VAM Project, respectively. The expanded uncertainties estimated for SA considering the concentration range from 2.67 to 6.67 μg/mL were 0.25, 0.36 and 0.35 μg/mL and for the concentration range from 6.67 to 18.67 μg/mL were 5.3%, 5.3% and 6.0% calculated by MCM, Nordtest/ISO 11352 respectively. It was concluded that the developed methodology allows to estimate the measurement uncertainty of a multivariate spectrophotometric analytical procedure by bottom-up and top-down approaches.

Features of measurement uncertainty evaluation during calibration of digital ohmmeters

The scheme for transferring the size of the unit of resistance during the calibration of digital ohmmeters at direct current is considered. The procedure for the measurement uncertainty evaluation is described: recording the measurement model and its refinement, evaluation of input and measured values, evaluation of standard uncertainties of the input and measured values, evaluation of the expanded uncertainty. The refined model includes the dependence of the resistance of the reference resistor on temperature and a correction to the drift of the resistance value of the reference resistor since its last calibration. To evaluate the expanded uncertainty, the kurtosis method was used. An uncertainty budget has been made, including the kurtosis of input and measured values. The use of the Excel package makes it possible to implement, based on this budget, a program for automation of measurement uncertainty calculations. An example of the measurement uncertainty evaluation during the calibration of a digital ohmmeter of type 2318 at a point of 1 mOhm using an electrical resistance coil R310 with an accuracy class of 0.01 is considered. The influence of nonlinearity of the measurement model on the estimates of the numerical value of the measurand and its combined standard uncertainty is studied. To verify the results, the distribution law of the measurand was modelled by the Monte Carlo method. An algorithm for determining the expanded uncertainty using the NIST Uncertainty Machine web application for the missing confidence level of 0.9545 is proposed. The comparison of the results of the measurement uncertainty evaluation by the kurtosis and Monte Carlo methods has shown their good agreement.

Research on analysis method of measurement uncertainty in the power performance assessment of tidal energy converters

The analysis on the measurement uncertainty of output power in the field test of tidal energy converters is an important process to evaluate the power characteristics performance of the tested tidal energy converter. Based on the field test data of the power characteristics performance assessment of a tidal energy converter, the measurement uncertainty calculation results of output power is analyzed. The research results show that: (1) The output power curve with measurement uncertainty information of the tested tidal energy converter that drawn in this paper, can reflect the discreteness and uncertainty of the output power during the field test period; (2) The sensitivity coefficient of tidal current velocity is a component that has a significant impact on the combined uncertainty of output power of tidal energy converters; (3) The change of the output power curve slope of the tested tidal energy converter can reflect the change of the sensitivity coefficient of tidal current velocity. The research results provide a reference for the field test work of power characteristics performance assessment of tidal energy converters in the future.

Evaluating the Measurement Uncertainty of On-Road NOx Using a Portable Emission Measurement System (PEMS) Based on Real Testing Data in China

An evaluation of the measurement uncertainty of on-road NOx emissions using portable emission measurement system (PEMS) based on real local testing data collected in China was carried out as per the type B method defined in the EN 17507 standard. The aim of this work was to quantify the “absolute” measurement uncertainty of PEMSs, which excluded “PEMS relative to laboratory constant volume sampler (CVS)” uncertainty from the calculation of on-road NOx measurement uncertainty using PEMSs. PEMS instruments from three mainstream manufacturers were employed. The zero drift of the NOx analyzers was evaluated periodically during the real driving emissions (RDE) test, and it was noticed that there was neither a linear nor step model of zero drift, with no correlation with the boundary conditions or measurement principle. Additionally, from the 256 valid RDE tests, the zero drift always ranged from 3.8 ppm to −3.8 ppm, and more than 95% of the span drifts were within a range of 1.5%. Based on the laboratory testing of ten vehicles using the worldwide harmonized light-duty vehicle test cycle (WLTC), the type B uncertainty of PEMS NOx measurements corresponding to China-6a and China-6b limits was assessed. An uncertainty of 26.5% for China-6a was found (NOx limit = 60 mg/km over the WLTC), which is very close to the 22.5% from the EU evaluation results (NOx limit = 80 mg/km over the WLTC); the uncertainty with respect to China-6b was found to be 42.8% because the type-I limit was tuned down to 35 mg/km. This result indicates that, with the ever-tightening regulatory limits of vehicle NOx emissions, big challenges will be posed in terms of the reliability of PEMS measurements, which requires PEMS manufacturers to improve the performance of the instruments and policymakers to refine the test procedures and/or result calculation method to minimize the impacts.

Evaluation of DNA Extraction Methods for Reliable Quantification of Acinetobacter baumannii, Klebsiella pneumoniae, and Pseudomonas aeruginosa

Detection and quantification of DNA biomarkers relies heavily on the yield and quality of DNA obtained by extraction from different matrices. Although a large number of studies have compared the yields of different extraction methods, the repeatability and intermediate precision of these methods have been largely overlooked. In the present study, five extraction methods were evaluated, using digital PCR, to determine their efficiency in extracting DNA from three different Gram-negative bacteria in sputum samples. The performance of two automated methods (GXT NA and QuickPick genomic DNA extraction kit, using Arrow and KingFisher Duo automated systems, respectively), two manual kit-based methods (QIAamp DNA mini kit; DNeasy UltraClean microbial kit), and one manual non-kit method (CTAB), was assessed. While GXT NA extraction kit and the CTAB method have the highest DNA yield, they did not meet the strict criteria for repeatability, intermediate precision, and measurement uncertainty for all three studied bacteria. However, due to limited clinical samples, a compromise is necessary, and the GXT NA extraction kit was found to be the method of choice. The study also showed that dPCR allowed for accurate determination of extraction method repeatability, which can help standardize molecular diagnostic approaches. Additionally, the determination of absolute copy numbers facilitated the calculation of measurement uncertainty, which was found to be influenced by the DNA extraction method used.

CONFORMITY ASSESSMENT IN INFRARED EAR THERMOMETER CALIBRATION

Body temperature is a basic physiological measurement used primarily for observation and diagnosis during surgery, pandemic diseases, intensive care, recovery or treatment. Various thermometers are clinically used for these measurements and can be divided into two categories, contact or non-contact. To have maximum confidence in the clinical performance of the temperature measuring instrument, it is important to calibrate the instrument traceable to the 1990 International Temperature Scale (ITS-90). The absence of traceable calibrations accredited to ISO/IEC 17025 can lead to insecurity in temperature measurement and in some cases can have a detrimental effect on patient care.Infrared or radiation thermometers are preferred in many different sectors from health to food, from automotive to agriculture, from iron and steel industry to chemistry due to their fast measuring capabilities, reasonable prices, wide measuring ranges and ease of use. In this study, ear thermometer calibration and measurement uncertainty calculations are investigated by using the traceability method via contact thermometer. Considering the maximum permissible error value of the device, conformity assessment is made according to the measurement result.

An image recognition measurement approach and uncertainty for overspeed governors employed in elevator safety

Elevator safety is closely related to public safety. Overspeed governor is a crucial part of the elevator safety system. Its inspection and calibration involve the measurement of tripping velocity. The frequently-used contact-type measurement method has risks. This paper proposes a non-contact image-recognizing measurement method by the camera, which includes the processes of rotor centre recognition, feature points matching, and tripping switches recognition. The velocity curve can be obtained by feature points displacement based on the rotor centre. Tripping switches recognition can determine the electrical and mechanical tripping velocities in the speed curve. The experimental results demonstrate that the proposed method has no significant difference from the common contact-type measurement method, while it significantly eliminates the risks of physical damage and improves measurement safety. Moreover, this paper proposes the deduction and calculation of measurement uncertainty decided by camera performance. Due to the enhancement of measuring safety, the proposed method will have further application in the field of elevator inspection. Practical application: The research on tripping velocity measurement for overspeed governor in this paper is principally based on image recognition with the help of a camera. The experiment result indicates that the proposed method is capable of completing the speed measurement for the overspeed governor without contact. The proposed method significantly mitigates the risks of physical damage and improves measurement safety rather than the contact-type measurement method. The proposed non-contact image-recognizing method can substitute for the existing contact-type method and contributes to the inspection, maintenance, and management of elevators, which will have further application prospects.

Calculation of measurement uncertainty of 20 Clinical Chemistry Analytes according to the practical ISO approach

Purpose: Measurement Uncertainty (MU) is a valuable tool for evaluating analytical performance and interpreting results in clinical laboratories. The International Organization for Standardization (ISO) has proposed a practical approach for MU calculation in its ISO/TS 20914:2019 guide. This study aimed to calculate the MU values of 20 clinical chemistry analyses per the ISO guideline and compare them with the Maximum expanded allowable measurement uncertainty (MAU) values.
 Methods: The study was performed using 6-month internal quality control (IQC) values (uRw) and calibrator uncertainty (ucal) in line with the recommendations of the ISO/TS 20914:2019 guideline. The common MU value was calculated for 20 clinical chemistry tests on two identical devices, Roche Cobas 6000 c501 (Roche Diagnostics, Mannheim, Germany) analyzers. The calculated MU values for the tests were compared with the current MAU values in the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) Biological Variation database (the current Clinical Laboratory Improvement Amendments/CLIA recommendation for Ethanol has been selected). 
 Results: MU values for Alanine aminotransferase, C-reactive Protein, Iron, Ethanol, Total Bilirubin, Triglyceride, and Blood urea nitrogen remained within the MAU limits. The MU values of the other 13 tests (excluding Aspartate aminotransferase, Glucose, and Potassium Level 2 IQC) exceeded the MAU values. 
 Conclusion: It was observed that the uRw value affected the MU value the most. Close monitoring and evaluation of uRw and thus IQC and implementation of corrective and preventive actions may reduce MU.

A Review of Effectiveness on Quality Management System for Calibration Activity (ISO 9001:2015, ISO/IEC 17025:2017 and Conventional Method)

Non-destructive test (NDT) is well-known testing and acts as an important and mandatory part of the quality system for the automotive, aerospace, and oil & gas industry. There are several available non-destructive tests (NDT) methods such as ultrasonic, magnetic, eddy current, and radiographic that intend to provide a measurement for the NDT inspector to interpret the reading of the equipment. The result of interpretation will determine the quality and defect detection. The calibration process of NDT equipment is a major element to make sure the equipment is precise and accurate. The calibration process will help to detect any failure of components in the NDT equipment. However, the current normal practice in the industry does not follow the best quality management system to perform calibration activities. Therefore, this paper (review) aims to extract the resulting traceability, competency of the calibrator, and calculation of measurement uncertainty. The 3 main procedures as reference are ISO 9001:2015, ISO/IEC 17025:2017, and the conventional method. All the 3 mentioned quality management systems will be compared, and the best quality management system will be identified to support the calibration activity.

Gwfish: A simulation software to evaluate parameter-estimation capabilities of gravitational-wave detector networks

An important step in the planning of future gravitational-wave (GW) detectors and of the networks they will form is the estimation of their detection and parameter-estimation capabilities, which is the basis of science-case studies. Several future GW detectors have been proposed or are under development, which might also operate and observe in parallel. These detectors include terrestrial, lunar, and space-borne detectors. In this paper, we present gwfish,11github.com/janosch314/GWFish. a new software to simulate GW detector networks and to calculate measurement uncertainties based on the Fisher-matrix approximation. gwfish models the impact of detector motion on PE and makes it possible to analyze multiband scenarios, i.e., observation of a GW signal by different detectors in different frequency bands. We showcase a few examples for the Einstein Telescope (ET) including the sky-localization of binary neutron stars, and ET’s capability to measure the polarization of GWs.

Practical Considerations for Clinical Laboratories in Top-down Approach for Assessing the Measurement Uncertainty of Clinical Chemistry Analytes.

The top-down (TD) approach using internal quality control (IQC) data is regarded a practical method for estimating measurement uncertainty (MU) in clinical laboratories. We estimated the MU of 14 clinical chemistry analytes using the TD approach and evaluated the effect of lot changes on the MU. MU values were estimated using subgrouping by reagent lot changes or using the data as a whole, and both methods were compared. Reagent lot change was simulated using randomly generated data, and the mean values and MU for two IQC datasets (different QC material lots) were compared using statistical methods. All MU values calculated using subgrouping were lower than the total values; however, the average differences were minimal. The simulation showed that the greater the increase in the extent of the average shift, the larger the difference in MU. In IQC data comparison, the mean values and MU exhibited statistically significant differences for most analytes. The MU calculation methods gave rise to minimal differences, suggesting that IQC data in clinical laboratories show no significant shift. However, the simulation results demonstrated that notable differences in the MU can arise from significant variations in IQC results before and after a reagent lot change. Additionally, IQC material lots should be treated separately when IQC data are collected for MU estimation. Lot changes in IQC data are a key factor affecting MU estimation and should not be overlooked during MU estimation.

Measurement uncertainty estimation technology: justification, conditions and experience of implementation in medical practice

In accordance with GOST R ISO 15189–2015 ‘Medical laboratories. Particular requirements for quality and competence’ for the report on the values of the measured value in the patient’s samples, the laboratory must determine and use the measurement uncertainty in the analytical phase. The article discusses in detail the differences between the general analytical error and measurement uncertainty. The authors have tested a typical algorithm for estimating measurement uncertainty. Mandatory conditions and an algorithm for calculating measurement uncertainty (at the analytical stage) in medical laboratories using quantitative immunochemiluminescence analysis are presented.

On the treatment of measurement uncertainty in stochastic modeling of basic variables

The acquisition and appropriate processing of relevant information about the considered system remains a major challenge in assessment of existing structures. Both the values and the validity of computed results such as failure probabilities essentially depend on the quantity and quality of the incorporated knowledge. One source of information are onsite measurements of structural or material characteristics to be modeled as basic variables in reliability assessment. The explicit use of (quantitative) measurement results in assessment requires the quantification of the quality of the measured information, i.e., the uncertainty associated with the information acquisition and processing. This uncertainty can be referred to as measurement uncertainty. Another crucial aspect is to ensure the comparability of the measurement results.This contribution attempts to outline the necessity and the advantages of measurement uncertainty calculations in modeling of measurement data-based random variables to be included in reliability assessment. It is shown, how measured data representing time-invariant characteristics, in this case non-destructively measured inner geometrical dimensions, can be transferred into measurement results that are both comparable and quality-evaluated. The calculations are based on the rules provided in the guide to the expression of uncertainty in measurement (GUM). The GUM-framework is internationally accepted in metrology and can serve as starting point for the appropriate processing of measured data to be used in assessment. In conclusion, the effects of incorporating the non-destructively measured data into reliability analysis are presented using a prestressed concrete bridge as case-study.