Components Of Measurement Uncertainty Research Articles

Measurement uncertainty of ethyl alcohol concentration in the exhaled breath of drivers and determination of sobriety at the time of incident.

The aim of the study was to determine the components of measurement uncertainty in the concentration of alcohol in exhaled breath and to determine the state of sobriety at the time of incident. Based on the literature review and the authors' experience in providing opinions for law enforcement and the judiciary, the influence of various factors on the final interpretation of sobriety state is described on the basis of measurement uncertainty of breath analyzers, uncertainty of retrospective and prospective calculations, and uncertainty related to the conversion of alcohol concentrations detected during breath and blood tests. The paper pays particular attention to interpreting the concentrations of ethanol in exhaled breath close to the legal limits of the state of sobriety and the state after alcohol use, or the state after alcohol use and the state of insobriety. Analyzing the results of an exhaled breath test concerning concentrations close to the values of 0.1 mg/dm3 and 0.25 mg/dm3, it is necessary to take into account the factors affecting the measurements obtained, including the measurement uncertainty of the determination of alcohol in exhaled breath, the processes of absorption, distribution and metabolism of ethyl alcohol, and the possibility of the presence of alcohol lingering in the oral cavity. The incorrect execution of measurements of the tested person's alcohol concentration is also a problematic issue. When determining sobriety state by means of retrospective and prospective calculations, it is important to remember that the uncertainty of the result is affected by a number of factors and depends, among other things, on the information provided by the suspect. Hence, the expert should draw conclusions particularly cautiously and any overestimation or underestimation of the components of uncertainty can lead to erroneous conclusions. Awareness of the uncertainties inherent in the results of a sobriety test or alcohol calculation allows for meaningful interpretation of test results and determination of the sobriety state of the person tested.

Traceable frequency measurements with counters

Received signals from Global Navigation Satellite Systems (GNSS) are nowadays widely used by industry laboratories for ensuring metrological traceability for their respective range of calibration services in the field of time and frequency. Usually, a local frequency standard is steered by continuous GNSS signal reception providing at its output stable and accurate reference signals for the laboratory measurement equipment, in general for synthesizers and counters. Reception of GNSS signals is surely an adequate and practical tool for the purpose, however further steps are needed to establish traceability in a strict metrological sense. Based on already available guidelines and publications, this paper is a contribution to the discussion how metrological traceability to internationally accepted standards can be established in a calibration laboratory. We restrict the discussion to equipment in common use which may not necessarily be of the highest sophistication. In this spirit, we develop a detailed scheme for an uncertainty budget comprising all links of the traceability chain from the device under test to the SI second, the scale-unit of Coordinated Universal Time. Then we go through and apply this scheme step by step to a demonstration setup for frequency measurements with a counter with varying operational parameters. In this framework, a novel approach to distinguish between components of statistical measurement uncertainty is introduced. Furthermore, the limiting uncertainty contributions are discussed and based on a suitable set of parameters an expression for the best measurement capability is given. With this scheme at hand a user may develop an uncertainty budget adapted to his own setup, especially if acceptance from a national accreditation body is sought.

The evaluation of the measurement uncertainty of the thousand-seed weight in accredited testing laboratories

The evaluation of the measurement uncertainty of the seed quality indicators is an integral part of testing in accredited testing laboratories. The thousand-seed weight is one of the essential indicators, the limit values of which are not standardized, but are taken into account when determining the cost of a lot of seeds or seeding rates.
 The developed method for evaluating the measurement uncertainty of the thousand-seed weight by measuring two weights of 500 seeds is presented in the paper. According to the analysis of a basic calculation formula, the impact of correctness and accuracy on the measurement uncertainty was assessed. It was shown that the major measurement uncertainty components are uncertainties of weighting and repeatability. The repeatability is advisable to be evaluated by Type В using the limit of repeatability, if the national standard specifies the testing method. The authors have analysed the conditions when other components can be neglected. The uncertainty budget and an example of its calculation were received.

Development and Traceability Method of a 100 kA Reference Impulse Current Measuring System

In order to improve the measurement accuracy of high impulse current, this paper presents the system composition, performance improvement and, traceability method of a 100 kA impulse current measuring system. Since the scale factor of the measuring system can be determined by the product of the scale factor of the components such as the shunt and the digital recorder, a method of component quantity traceability is proposed. Based on a shunt with rated current of 100 kA, a stable measuring system is developed. In addition, a reference impulse current calibrator and a step current generator for traceability are developed, so that the impulse scale factor of the shunt considering skin effect can be accurately calibrated. A single influence quantity independent quantification method was proposed. The influence of measurement error of 100 kA impulse current measuring system is analyzed quantitatively. Based on the high current test results and theoretical analysis, the measurement uncertainty components of peak current and time parameters are evaluated. The expanded uncertainty of the scale factor and time parameters were 0.4% ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> = 2) and 0.8% ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> = 2) respectively. Evaluation results demonstrate that the developed measuring system can accurately reproduce and measure the high exponential lightning impulse current.

Economic optimization of acceptance interval in conformity assessment: 1. Process with no systematic effect

In inspections for conformity assessment, an acceptance interval smaller than the tolerance interval is often determined in order to reduce the risk of consumers obtaining non-conforming items in the market. The presence of non-conforming items in the market impairs the evaluation of items by customers and may have an impact on revenue by decreasing prices. However, setting too small an acceptance interval reduces the revenue from the process by decreasing the number of the items available in the market. We thus propose a method to determine the optimum acceptance interval in conformity assessment by means of maximization of the revenue from processes. For this purpose, we give a mathematical model for the price of an item and its cost in the production process. Through theoretical analysis and simulations, it is shown that a parameter in the price model is the key in the optimization. In this paper we report a method for processes where no systematic effect component of measurement uncertainty exists, and in part 2 of this series we will report an extended method in which systematic effects are taken into consideration.

Calibration of Ultrasonic Flaw Detectors in Accordance with ISO 22232-1:2020

This paper presents the ultrasonic flaw detectors calibration system at Standards and Calibration Laboratory (SCL) developed in accordance with the Group 2 tests of ISO 22232-1:2020. The calibration system contains a delay-pulse generator, a function generator, an amplifier, an oscilloscope and a set of tunable attenuators. The measurement setup, model and uncertainty components for each tests are presented. The difference in test parameters from the preceding international standard EN 12668-1:2010 are also reviewed and compared.

Calibration of Loop Antennas in Accordance with CISPR 16-1-6:2014+AMD1:2017 at SCL

This paper presents the ultrasonic flaw detectors calibration system at Standards and Calibration Laboratory (SCL) developed in accordance with the Group 2 tests of ISO 22232-1:2020. The calibration system contains a delay-pulse generator, a function generator, an amplifier, an oscilloscope and a set of tunable attenuators. The measurement setup, model and uncertainty components for each tests are presented. The difference in test parameters from the preceding international standard EN 12668-1:2010 are also reviewed and compared.

Instrumental Uncertainty of Conductance Transducers for Maritime Reduced-Scale Models

This paper aims to determine the instrumental measurement uncertainty of conductance transducers for maritime reduced-scale models developed in hydraulic experimental facilities. These transducers are used for the measurements of wave levels and their variations under a dynamic regime (being the measurement principle and method briefly described in the paper). Several metrological characterization methods are also presented, aiming to identify and quantify measurement uncertainty components, namely electrical stability, linearity, reversibility, repeatability, and thermal influence. The obtained results were applied in the evaluation of the transducer instrumental measurement uncertainty.

Problems with evaluating readings of pulse oximeters used at home during the ongoing COVID-19 pandemic

The author presents the problems related to pulse oximetry, taking into account both the current state-of-the-art as well as her own long-standing experience in this field. The COVID-19 pandemic continues and has raised interest in home application of pulse oximeters due to their potential benefit, which may be warning of a drop in blood oxygenation due to lower respiratory capacity. However, it should be emphasized that these devices have limitations, both of a physiological and technical nature, and some problems related to the reliability and scope of the measurements still remain unresolved. Phenomena which limit processing reliability of the quantity to be sensed, i.e., the oxygen saturation SaO2%, are presented. Specific groups of affecting factors are distinguished in an approach of their contribution to the measurement uncertainty components. Full Text: PDF ReferencesJ.W. Severinghaus, "Crediting six discoverers of oxygen", Adv. Exp. Med. Biol. 812 (2014). CrossRef F.A. Duck, "Physical properties of tissue: a comprehensive reference book" (San Diego, Academia Press 1990). CrossRef J.G. Webster, "Design of pulse oximeters" (Bristol, IOP Publishing Ltd 1997). CrossRef A.A. Alian and K.H Shelley, "Photoplethysmography", Anesthesiology 28, 4 (2014). CrossRef N. Moukaddam and A. Shah, "Psychiatrists beware! The impact of COVID-19 and pandemics on mental health", Psychiatric Times 37, 3 (2020). CrossRef S.S. Morse, Proc Nat. Acad Sci 104, 18 (2007). CrossRef W.A. Schrading, B. McCafferty, J. Grove, and D.B. Page, "Portable, consumer‐grade pulse oximeters are accurate for home and medical use: Implications for use in the COVID‐19 pandemic and other resource‐limited environments", JACP Open, 1 (2020). CrossRef K.E.J. Philip, B. Bennet, S. Fuller, et al., "Working accuracy of pulse oximetry in COVID-19 patients stepping down from intensive care: a clinical evaluation ", BMJ Open Resp. Res. 7 (2020). CrossRef S. Seifi, A. Khatony, G. Moradi, A. Abdi, and F. Najafi, "Accuracy of pulse oximetry in detection of oxygen saturation in patients admitted to the intensive care unit of heart surgery: comparison of finger, toe, forehead and earlobe probes", BMC Nursing 17, 15 (2018). CrossRef A. Cysewska-Sobusiak, "A modern approach to the determination of expanded uncertainty in noninvasive blood oximetry", Measurement 25 (1999). CrossRef A. Cysewska-Sobusiak, "The importance of the combined teaching and research work in the education of biomedical engineering", Biocybernetics and Biomedical Engineering 22, 4 (2002). CrossRef A. Cysewska-Sobusiak, "Noninvasive optoelectronic monitoring of the living tissues vitality", 3rd Int. Workshop on Robot Motion and Control, Nov. 2002 (2002). CrossRef A. Cysewska-Sobusiak, "Examples of acquisition and application of biooptical signals", Phot. Lett. Poland 11, 2 (2019). CrossRef

Computation of epistemic uncertainty due to limited data samples in small field dosimetry using Fuzzy Set Theory.

To estimate the epistemic (or fuzzy) uncertainty, arising due to limited data samples in the measurement of the output factors (OFs) of the small fields using Fuzzy Set Theory (FST). EBT3 film samples of size 50 × 50 mm2 were used for the measurement of the OF of stereotactic radiosurgery (SRS) cones of size 4, 6, 7.5, 10, 12.5 and 15 mm diameter, normalized with respect to the output of 100 × 100 mm2 open field size. Three measurements were done per cone/field size. Red color channel was chosen for the dosimetry purpose, net optical density (NOD) was converted to the dose using non-linear relation. To estimate the epistemic uncertainty associated with the measured OFs due to limited number of data samples, a triangular fuzzy number (TFN) was assumed as the fuzziness in the dose delivered by the individual SRS cone/field. Uncertainty in the OF was estimated by applying the Fuzzy Vertex Method (FVM). The membership functions of the OF were constructed for each cone size and the nature of the uncertainty in the OF of the cones was expressed in the terms of its fuzziness. For the sake of completeness of the study, the statistical uncertainty involved in the procedure has also been calculated. The statistical and fuzzy uncertainties in the measurement of OF of cones range from 3.28 to 6.25% and 2.58 to 5.44% respectively. The smallest cone of 4 mm has the largest values of statistical and fuzzy uncertainties. The membership functions of the OF for the studied cones were triangular in nature. The epistemic uncertainty arising due to limited number of data samples holds a significant fraction of the prescribed dose, and therefore, should not be ignored in the total uncertainty estimation. This study highlights the significance of epistemic component of measurement uncertainty arising out due to the insufficient/limited number of measurements of a quantity.

Estimating quality of indirect measurements of sea water sound velocity by CTD data

The publication presents the results of calculations of the uncertainty estimates for indirect measurements of the sound velocity using CTD data. The sound velocity dependence on the input parameters was analyzed. The input parameters include absolute salinity, temperature and hydrostatic pressure. The diagrams of the sensitivity coefficients of the dependence of the sound velocity on the input parameters are constructed, which are applicable for practical calculations. For various classes of measurement instruments the diagrams of the measurement uncertainty components on each of three input parameters and the diagram of the combined standard uncertainty of the indirect measurements of the sound velocity were calculated. The uncertainty estimate diagrams for the sound velocity measurement in the sea water can be used in oceanography investigations and for the work of metrological laboratories. The authors defined the potential applications of CTD probes with various precision for the indirect measurements of sound velocity.

STANDARDS IN FORCE MEASUREMENTS

Force measurement is an important aspect in testing and determining the characteristics of units, machine parts and materials, building materials and structures, the quality of metallurgical products, as well as when assessing the conformity of force and weight transducers. The purpose of this study is to select the optimal procedure and methodology for realization, storage and transferring of the unit size of force in the country, as well as to ensure its traceability to the international system of SI units. This paper analyzes existing methods of realization, storage and transferring of unit size, such as deadweight force standard machines, hydraulic amplification force standard machines, lever amplification force standard machines and systems (groups) of several force transducers (BU system) that can be used as reference by metrological institutes and calibration laboratories. The main principles of operation of the above mentioned machines of realization of a unit of force are considered, including the components of measurement uncertainty and the nature of their origin with the possibility of further consideration in the uncertainty budget. The calibration and measurement capabilities of the world's leading metrological institutions, which maintain different classes of force standard machines for reproducing the size of a unit of force, namely the measurement range, measurement uncertainty, as well as overall dimensions, operating features, etc. are analyzed. The results of the analysis of the disadvantages and advantages of the three main classes of force standard machines for reproducing the size of a unit of force are presented in this article. Conclusions are made on the creation of a national standard of the force unit based on the installation of lever amplification force standard machines, which are based on the analysis of methods of reproduction and transfer of the size of a unit of force, which will occupy positions among the world's leading metrological institutions.

Estimation of measurement uncertainty including surrogate recoveries in the study of polycyclic aromatic hydrocarbons in marine sediments

We examine the use of surrogates in the measurement of concentrations of polycyclic aromatic hydrocarbons (PAH) in marine sediment, consider shortcomings of current interpretations of the results from this widely used approach, and propose an alternative data treatment. We focus on the current common practice of accepting all data within a predefined range of acceptable recoveries as equally valid and propose treating surrogate recovery data as one component of measurement uncertainty. Our analysis leads us to conclude that the more uniform surrogate recoveries are, the more justified the assumption that they reveal measurement bias and appropriately can be used as corrections; but that the less uniform recoveries are, the greater the need to treat them as a source of measurement uncertainty. We recognize that acceptance of the ideas presented here will require much thought and refinement by the environmental analytical community. We welcome a thorough discussion.

Improvement of the Russian National Secondary Standard of the Unit of Length Using Latest Ultra-Stable Laser Equipment

Introduction. Increasing demands of precise geometry measurements by science and industry cause the necessity of improvement in an associated branch of legal and practical metrology. One of the most significant fields is the measurement of internal dimensions and so the issues with the unit of meter transfer. Now we face the situation when the current accuracies of National standards of different levels in corresponding traceability chain (reference rings measurements) get close to each other. This means that we have to make the standard of upper level more precise. One of the obvious ways is to apply the latest ultra-stable laser locked to a frequency comb.Objective. The objective is to propose possibilities for improvement of the National secondary standard of the unit of length by researching its measuring capabilities to minimize measurement uncertainty.Materials and methods. The calculation of expanded uncertainty of internal diameter measurements by the National secondary standard of the unit of length is performed according to the international document «Guide to the Expression of Uncertainty in Measurement» JCGM 100:2008 approved by BIPM. The secondary standard research results represented in previous reports and publications are also taken into consideration.Results. Detailed uncertainty budget for the proposed measuring system is given as well as graphical data representing the accuracy improvement.Conclusion. Actions for minimization of measurement uncertainty components of the National secondary standard of the unit of length in the field of reference ring internal diameter measurements in combination with state-of-the-art laser interferometer system improve it to the next frontiers of accuracy and precision.

Can the Sperm Class Analyser (SCA) CASA-Mot system for human sperm motility analysis reduce imprecision and operator subjectivity and improve semen analysis?

Semen analysis (SA) is considered mandatory for suspected male infertility although its clinical value has recently become questionable. Sperm motility is an essential parameter for SA, but is limited by high measurement uncertainty, which includes operator subjectivity. Computer-assisted sperm analysis (CASA) can reduce measurement uncertainty compared with manual SA. The objective of this study was to determine whether the Sperm Class Analyser (SCA) CASA-Mot system could reduce specific components of sperm motility measurement uncertainty compared with the World Health Organization (WHO) manual method in a single laboratory undertaking routine diagnostic SA. The study examined: (i) operator subjectivity; (ii) precision, (iii) accuracy against internal and external quality standards; and (iv) a pilot sub-study examining the potential to predict an IVF fertilisation rate. Compared with the manual WHO method of SA on 4000 semen samples, SCA reduces but does not completely eliminate operator subjectivity. Study SCA and CASA-Mot are useful tools for well-trained staff that allow rapid, high-number sperm motility categorization with less analytical variance than the manual equivalent. Our initial data suggest that SCA motility may have superior predictive potential compared with the WHO manual method for predicating IVF fertilization.

Mental Experiment in Metrology and Representation of Measurement Uncertainty in a Complex Form

The essence of the thought experiment and its use in metrology for evaluating and presenting measurement results are studied. An imaginary experiment has a hypothetical-deductive structure, carried out on the basis of the developed program, plan-scheme, is based on experience and is based on the real laws of the phenomena under study and does not go beyond the boundaries of empirical preconditions. The term «uncertainty» of measurement is considered in three aspects: quantitative knowledge of objects of the real world, the technical procedure for obtaining pragmatic measurement information, evaluation of the measured information for making informed decisions and risk management. An analyzed of the shortcomings of exis­ting methods to assess the components of measurement uncertainty, based on the specific features of the GUM concept. In this concept, all components of measurement uncertainty are grouped abstractly into two categories - A and B without sufficient justification of the classification criteria. A method for classifying the components of uncertainty based on a real or mental experiment is proposed, and the results obtained are referred to as real (standard) uncertainty «and» imagi­nary (standard) uncertainty». The total uncertainty is considered as a complex value and is calculated on the basis of orthogonal vectors of the results of real and imaginary experiments. The proposed interpretation of the uncertainty of measurement gives a better understan­ding of the nature of uncertainty, simplifies entries and calculations.

The Role of Measurement Uncertainty in Health Technology Assessments (HTAs) of In Vitro Tests.

IntroductionNumerous factors contribute to uncertainty in test measurement procedures, and this uncertainty can have a significant impact on the downstream clinical utility and cost-effectiveness of testing strategies. Currently, however, there is no clear guidance concerning if or how such factors should be considered within Health Technology Assessments (HTAs) of tests.ObjectiveThe aim was to provide an introduction to key concepts in measurement uncertainty for the HTA community and to explore, via systematic review, current methods utilised within HTAs.MethodsHTAs of in vitro tests including a model-based economic evaluation were identified via the Centre for Reviews and Dissemination (CRD) HTA database and key reimbursement authority websites. Data were extracted to explore the specific components of measurement uncertainty assessed and methods utilised. The findings were narratively synthesised.ResultsOf 107 identified HTAs, 20 (19%) attempted to assess components of measurement uncertainty: 15 did so via some form of pre-model assessment (such as a literature review or laboratory survey); four also included components within the economic model; and one considered measurement uncertainty within the model only. One study quantified the impact of measurement uncertainty on cost-effectiveness and found that this parameter significantly changed the results, but did not impact the overall decision uncertainty.ConclusionA minority of HTAs identified from this review used various approaches to assess and/or incorporate the impact of measurement uncertainty, indicating that these assessments are feasible. Uncertainty remains around best practice methodology for conducting such analyses; further research is required to ensure that future HTAs are fit for purpose.Electronic supplementary materialThe online version of this article (10.1007/s40273-018-0638-1) contains supplementary material, which is available to authorized users.

Software for visualization and analysis of signals from devices for measurement of shape deviations

The software developed at the Institute of Metrology and Biomedical Engineering is presented, which can be used for comparative analysis of rotary profiles of mechanical elements measured with FMM. The distinguishing feature of the software amongst solutions offered by the machine manufacturers is the ability to compare profiles recorded applying different measuring machines and at different times. In addition, the software allows to estimate the impact of the most important components of measurement uncertainty. As a result, it can be successfully used to evaluate the wear of mechanical components, such as motor pistons.

Uncertainty estimation of the determination of chemical sum parameters in water

Sum parameters (otherwise known as composite parameters) describe similar chemical, physicochemical or biological characteristics of different substances, substance groups or mixtures of substances. These might contain the same chemical element. Such parameters are total organic carbon or total bound nitrogen. Chemical oxygen demand is a shared chemical characteristic—the oxidizability of constituents by dichromate. The focus of the paper is on the uncertainty estimation of the determination of chemical sum parameters in water samples from method validation derived data—total organic carbon, chemical oxygen demand, biochemical oxygen demand, total bound nitrogen and total suspended solids. The results for the measurement uncertainty estimations according to ISO 21748 and ISO 11352, as only applicable to the field of water analysis, are presented and compared. Based on the results obtained and the experimental design, the use of ISO 11352 for the measurement uncertainty estimation is recommended. This international standard employs fewer determinations (a minimum number of eight measurements are required, compared to fifteen), fewer working days (one compared to five) and easier measurement uncertainty components’ calculations and even gives opportunity for routine laboratories to use standard solutions over the more expensive certified reference materials for the measurement uncertainty estimation during the method validation in water analysis.

Evaluation and optimisation of methylene blue removal measurement uncertainty in photodegradation studies

The photodegradation of carcinogenic and teratogenic organic contaminants, such as active substances of medicines or preservatives of personal care products, not removed from wastewaters by conventional treatments, is a promising solution to reduce the impact of such emissions. Nevertheless, new catalysts need to be developed to make this technology feasible. Catalysts performance can be assessed from photodegradation tests using degradation markers such as methylene blue. The difference between the photodegradation kinetic constants of two catalytic alternatives is meaningful if its absolute value is larger than the expanded uncertainty of the difference, which results from the combination of relevant measurement uncertainty components, namely pollutant concentration before and after depletion and irradiation time. This work presents algorithms for estimating differences of kinetic constants of methylene blue removal, with uncertainty, implemented in a user-friendly MS Excel spreadsheet. The developed measurement models allow the optimisation and reliable comparison of kinetic constants. This tool is particularly useful to distinguish small efficiency differences of catalysts with equivalent production and use costs. If a portion of the methylene blue solution subjected to irradiation is used to calibrate the spectrometer between 0.26 mg L−1 and 1.3 mg L−1 in a wavelength interval between 550 nm and 700 nm, if the solution irradiation time is larger than 11 min and the irradiated solution is quantified after dilution with negligible uncertainty, it is possible to distinguish the difference of kinetic constants between 0.11 ms−1 and 0.56 ms−1.