Metrology Issues Research Articles

The Behaviour of Consumer and Strategy of Development of Legal Metrology Performance

This study explores the knowledge, attitude, and practice (KAP) in legal metrology since there is very little information on knowledge, attitude, and practice concerning legal metrology. The survey data gathered from 24.360 respondents across 34 provinces in Indonesia assessed the understanding concerning legal metrology by applying descriptive statistics, correlation, and multinomial regression analysis. The results show the consumers generally have better knowledge in legal metrology, an excellent attitude about the importance of legal metrology, and critical behaviour in mitigating fraudulence risk when doing trade transactions at the marketplace. Variable of gender and age tends to impact knowledge, attitude, and practice concerning legal metrology issues. The study also found that the relationship between knowledge, attitude, and practice is likely to be non-linear. The outcomes of exploring the behaviour of consumers through knowledge, attitude, and practice in legal metrology can be beneficial for legal metrology authorities to analyze the impact of setting policies and programs. Also, to develop a strategy to increase public awareness in legal metrology so that the consumers can be more critical in protecting themselves from various fraudulence in measurement in trade transactions.

METROLOGICAL ISSUES OF MATERIALS SCIENCE AND NEW APPROACHES TO THEIR SOLUTIONS

METROLOGICAL ISSUES OF MATERIALS SCIENCE AND NEW APPROACHES TO THEIR SOLUTIONS

Reliability of Body Temperature Measurements Obtained with Contactless Infrared Point Thermometers Commonly Used during the COVID-19 Pandemic.

During the COVID-19 pandemic, there has been a significant increase in the use of non-contact infrared devices for screening the body temperatures of people at the entrances of hospitals, airports, train stations, churches, schools, shops, sports centres, offices, and public places in general. The strong correlation between a high body temperature and SARS-CoV-2 infection has motivated the governments of several countries to restrict access to public indoor places simply based on a person’s body temperature. Negating/allowing entrance to a public place can have a strong impact on people. For example, a cancer patient could be refused access to a cancer centre because of an incorrect high temperature measurement. On the other hand, underestimating an individual’s body temperature may allow infected patients to enter indoor public places where it is much easier for the virus to spread to other people. Accordingly, during the COVID-19 pandemic, the reliability of body temperature measurements has become fundamental. In particular, a debated issue is the reliability of remote temperature measurements, especially when these are aimed at identifying in a quick and reliable way infected subjects. Working distance, body–device angle, and light conditions and many other metrological and subjective issues significantly affect the data acquired via common contactless infrared point thermometers, making the acquisition of reliable measurements at the entrance to public places a challenging task. The main objective of this work is to sensitize the community to the typical incorrect uses of infrared point thermometers, as well as the resulting drifts in measurements of body temperature. Using several commercial contactless infrared point thermometers, we performed four different experiments to simulate common scenarios in a triage emergency room. In the first experiment, we acquired several measurements for each thermometer without measuring the working distance or angle of inclination to show that, for some instruments, the values obtained can differ by 1 °C. In the second and third experiments, we analysed the impacts of the working distance and angle of inclination of the thermometers, respectively, to prove that only a few cm/degrees can cause drifts higher than 1 °C. Finally, in the fourth experiment, we showed that the light in the environment can also cause changes in temperature up to 0.5 °C. Ultimately, in this study, we quantitatively demonstrated that the working distance, angle of inclination, and light conditions can strongly impact temperature measurements, which could invalidate the screening results.

30 years to COOMET: results and prospects for cooperation

The history of Euro-Asian Cooperation of National Metrological Institutions (COOMET) has already spanned three decades (12 June 1991 is considered the date of its establishment – the day when the COOMET Memorandum of Understanding was signed). COOMET is an officially recognized regional metrology organization, as well as a regional legal metrology organization. Cooperation in COOMET and its outcomes allow member countries to successfully tackle metrological issues, faced by the national economy under market globalization, as well as to ingrate in the international metrological system. A brief overview of the history of creation and results of activity of COOMET is provided. The effectiveness of cooperation is evaluated, the promising areas of COOMET's activities are outlined.

Reproduction of air velocity in the entrance region of the test pipe in a wind tunnel

The airflow development in the pipe, in the entrance region of the wind tunnel located in the Lithuanian Energy Institute, the laboratory of Heat Equipment Research and Testing is investigated to analyze the conditions for the reproduction of air velocity values. The analysis is performed to reveal undeveloped flow conditions where the calibration of the devices is usually made, the entrance region of the pipes, or free stream from the nozzles. In this study, different flow regimes have been investigated using different air velocity measurement methods. Experimental and numerical results clearly show the features of the developing flow. They both demonstrate the stable core of the velocity profile up to 5 D in the pipe and ≤1 D from the entrance into the free stream in the testing chamber. Ultrasonic anemometer (UA) installed in the aerodynamic test facility shows reliable and highly comparable results with another non-intrusive device – laser Doppler velocimeter (LDA) in a range of velocities from 0.05 m/s up to 30 m/s. UA integrated into the wind tunnel is not found to be used for metrological issues for air velocity. Due to the fast response, they both enabled to analyze fluctuations in the flow. Local vortices identified in the flow have influenced the low-frequency fluctuations and the scatter of measurement results. Moreover, high-frequency fluctuations found in the flow originated from the flow turbulence and might be due to the electronic or acoustic noise. The stabilization of the entrance region in the pipe influences the mean value of air velocity, the transversal distribution of velocity and the development of axial velocity in different test sections of the pipe in a wind tunnel. Along with the recirculation zones in cavities of ultrasonic transducers, these factors are essential that make an impact on the reproduction of air velocity value.

Prognosis and Multiobjective Optimization of the Sampling Plan for Cylindricity Evaluation

The actualization of the befitting sampling strategy and the application of an appropriate evaluation algorithm have been elementary issues in the coordinate metrology. The decisions regarding their choice for a given geometrical feature customarily rely upon the user’s instinct or experience. As a consequence, the measurement results have to be accommodated between the accuracy and the inspection time. Certainly, a reliable and efficient sampling plan is imperative to accomplish a dependable inspection in minimal time, effort, and cost. This paper deals with the determination of an optimal sampling plan that minimizes the inspection cost, while still promising a measurement quality. A cylindrical-shaped component has been utilized in this work to achieve the desired objective. The inspection quality of the cylinder using a coordinate measuring machine (CMM) can be enhanced by controlling the three main parameters, which are used as input variables in the data file, namely, point distribution schemes, total number of points, and form evaluation algorithms. These factors affect the inspection output, in terms of cylindricity and measurement time, which are considered as target variables. The dataset, which comprises input and intended parameters, has been acquired through experimentation on the CMM machine. This work has utilized state-of-the-art machine learning algorithms to establish predictive models, which can predict the inspection output. The different algorithms have been examined and compared to seek for the most relevant machine learning regression method. The best performance has been observed using the support vector regression for cylindricity, with a mean absolute error of 0.000508 mm and a root-mean-squared error of 0.000885 mm. Likewise, the best prediction performance for measuring time has been demonstrated by the decision trees. Finally, the optimal parameters are estimated by employing the grey relational analysis (GRA) and the fuzzy technique for order performance by similarity to ideal solution (FTOPSIS). It has been approved that the values obtained from GRA are comparable with those of the FTOPSIS. Moreover, the quality of the optimal results is bettered by incorporating the measurement uncertainty in the outcome.

Electromagnetic and magnetic methods of non-destructive testing for control of damage accumulation in structural steels and alloys (review)

Control of the stress-strain state, compressive and tension stresses, accumulated fatigue damage is one of the goals of non-destructive testing. We consider data of current research in the field of eddy current and electromagnetic methods of non-destructive testing aimed at solving the problem of monitoring the accumulated damage in structural steels and alloys. Developments for practical implementation of the coercive force method, the eddy current structurescopy of non-magnetic materials, the method of higher harmonics and remanence-based control, the method of magnetic noise (Barkhausen noise) are considered. The physical foundations of non-destructive testing methods are considered along with their brief comparative analysis. Examples of non-destructive testing of critical units, such as operating oil and gas pipelines, aircraft parts, bearing parts, pressure vessels, crane parts, etc. are given. The possibility of using the eddy current method for control of the austenitic phase of cold rolled austenitic steels (AISI 304, AISI 321, AISI 316) is analyzed. The examples of static and fatigue tests of the samples of various steels and alloys are given: St3, St20, St45, D16T, AMg6, AMg6N, 12Kh18N9T, 08Kh18N9, 40Kh, R91. Metrology issues and the impact of interfering parameters affecting the measurement error are considered. The equipment used for a number of methods is discussed. Conclusions regarding the limits of applicability and limitations of the considered methods are drawn. The review provides links to both the fundamental works in the field of electromagnetic structurescopy and to modern research in this area which is important for the practical implementation of the devices based on electromagnetic and magnetic methods of non-destructive testing.

Materials Research & Measurement Needs for Ceramics Additive Manufacturing.

We report on a recent workshop dedicated to additive manufacturing (AM) of ceramics that was held at the National Institute of Standards and Technology (NIST) in November 2019. This two-day all-invited meeting brought together experts from industry, government agencies and academia to review the state of the field and identify the most pressing applied materials research and metrology issues which, if addressed, could accelerate the incorporation of AM methods into commercial ceramic manufacturing. Besides the AM technologies, the discussions included consideration of the necessary post-processing steps. We highlight some of the successes and challenges for the adoption of ceramics AM on an industrial scale, as viewed by the workshop participants. We also propose actions for the ceramic community to facilitate the wider commercialization of these fabrication methods.

64‐2: Metrology of Non‐Planar Light Sources Using Near‐Field Goniometric Measurement Method

In this paper we study the metrology issues of non‐planar light sources (NPLSs). We use near‐field (NF) goniometric measurement method to characterize the NPLSs. By using the NF method, we obtain the luminance image, the intensity, the spectra and the color of the source as a function of the ray angle, i.e., the zenith and azimuth angles in spherical coordinate system. The NF light rays are used to obtain the characteristics of the light source at far‐fields by post processing. The results of the NPLS metrology and the features of the NF goniometric measurement system are reported.

A Form-Free and High-Precision Metrological Method for the Twist of Aeroengine Blade

In order to solve the problems in the accuracy and adaptability of the existing methods for blade twist measurement, a high-precision and form-free metrological method of blade twist based on the parameter evaluation of twist angular position and twist angle is proposed in the study, and the theoretical model, the measurement principle and the key technologies of the method are discussed in detail. Three key issues of the twist metrology of a blade are solved based on technologies of calibration, a priori planning and geometric analysis: aeroengine axis matching, high-precision coordinate acquisition of the leading edge and the trailing edge, and extraction of twist angular position of the profile. The measurement path planning, sampling strategy optimization and high-precision coordinate collection are executed automatically without theoretical model data of the measured blade, thus the form-free and high-precision metrology of the blade twist is achieved. The research results show that the metrological method of blade twist presented in this study is effective, and that its measurement uncertainty is less than 0.01°. This method is form-free, efficient and accurate, and can solve the problems of high-precision measurement and evaluation for the twist of aeroengine blade primely.

Multiobjective optimization for target design in diffraction-based overlay metrology.

Overlay target design is an important issue in overlay metrology, whose aim is to probe the optimal overlay target to achieve good performance on measurement precision and accuracy even in the presence of process variation. In this paper, the target design problem is first formulated as a multiobjective optimization problem and then solved by the multiobjective genetic algorithm. The feasibility of the proposed method is verified based on simulations carried out on two overlay targets. The results reveal that measurements with high precision, accuracy, and process robustness could be achieved on the targets designed by the proposed method.

Temporal phase unwrapping using deep learning

The multi-frequency temporal phase unwrapping (MF-TPU) method, as a classical phase unwrapping algorithm for fringe projection techniques, has the ability to eliminate the phase ambiguities even while measuring spatially isolated scenes or the objects with discontinuous surfaces. For the simplest and most efficient case in MF-TPU, two groups of phase-shifting fringe patterns with different frequencies are used: the high-frequency one is applied for 3D reconstruction of the tested object and the unit-frequency one is used to assist phase unwrapping for the wrapped phase with high frequency. The final measurement precision or sensitivity is determined by the number of fringes used within the high-frequency pattern, under the precondition that its absolute phase can be successfully recovered without any fringe order errors. However, due to the non-negligible noises and other error sources in actual measurement, the frequency of the high-frequency fringes is generally restricted to about 16, resulting in limited measurement accuracy. On the other hand, using additional intermediate sets of fringe patterns can unwrap the phase with higher frequency, but at the expense of a prolonged pattern sequence. With recent developments and advancements of machine learning for computer vision and computational imaging, it can be demonstrated in this work that deep learning techniques can automatically realize TPU through supervised learning, as called deep learning-based temporal phase unwrapping (DL-TPU), which can substantially improve the unwrapping reliability compared with MF-TPU even under different types of error sources, e.g., intensity noise, low fringe modulation, projector nonlinearity, and motion artifacts. Furthermore, as far as we know, our method was demonstrated experimentally that the high-frequency phase with 64 periods can be directly and reliably unwrapped from one unit-frequency phase using DL-TPU. These results highlight that challenging issues in optical metrology can be potentially overcome through machine learning, opening new avenues to design powerful and extremely accurate high-speed 3D imaging systems ubiquitous in nowadays science, industry, and multimedia.

A metrological approach to the analysis of choroidal thickness by optical coherence tomography 3D scans in myopia research

In myopia research, changes of choroidal thickness in response to optically induced signals serve as predictor for changes in axial length that might be correlated with myopia progression. Optical coherence tomography (OCT) provides a tool for imaging the choroid, however, with certain difficulties because of a limited visibility of the scleral-choroidal interface. Considering the previously reported effect sizes of thickness change in human myopia research, this study investigated the repeatability of automated 3D choroidal segmentation across the macular area of 6 × 6 mm2. Fifteen subjects underwent nine volume scans in two OCT devices with analysis of the 95% interval of repeatability, intersubject and intrasubject variations, as well as interdevice agreement. Repeatability generally improved with increasing eccentricity from the fovea. The nasal perifoveal region exhibited the best repeatability with ±19 and ±21 μm in both OCT devices, whereas the subfovea showed a repeatability of ±57 and ±44 μm, respectively. High inter- and intrasubject variations were observed, together with a negative bias in the device agreement. Although there is still limited data on thickness changes of the nasal choroid, future studies could focus more on measuring the effect size in the nasal perifoveal area to account for metrological issues in choroidal segmentation.

Metrology Issues of a Non-Planar Light Source with Radius Comparable to that of Measurement Field

Metrology Issues of a Non-Planar Light Source with Radius Comparable to that of Measurement Field

Metrology Issues of a Non-Planar Light Source with Radius Comparable to that of Measurement Field

Metrology Issues of a Non-Planar Light Source with Radius Comparable to that of Measurement Field

Actual metrological and legal issues of non-destructive testing

The article is devoted to analyzing problems of metrological support and legal regulation in the sphere of non-destructive testing (NDT). Differences between the measurement technique and NDT have been analyzed. The necessity to apply the principles of metrological traceability to the NDT technique, equipment and test pieces has been announced. It has been suggested to view NDT as multi-parameter measurements. An example of the reference measuring system for complex calibrations of metal coatings measures on metal bases to calibrate eddy-current thickness gages of coatings has been given.

Field verification of thermal energy meters through ultrasonic clamp-on master meters

The measurement of heat consumption in buildings through thermal energy meters presents numerous metrological issues due, for example, to the installation and operational conditions (e.g. presence of plant constraints, low flow rates, low temperature differences between flow and return) leading often to unacceptable measurement errors and uncertainties. Therefore, in several EU countries, to guarantee consumer protection it is mandatory to carry out periodic inspection both in the laboratory and in the field to assess their accuracy, while in service. In this work, the authors present the results of experimental campaigns aimed at analysing the key metrological concerns for clamp-on master meters during in-field verification of thermal energy meters. The results showed that particular care should be paid to the meter configuration and installation of the transducer and that legal metrology statutes in terms of permissible error and uncertainty for fielded meters are often very difficult to comply with.

43‐2: Optical Characteristics of Curved Flexible Light Sources (FLSs) with Small Radius and Metrology Issues

Planar flexible light sources (FLSs) have a variety of features that give a boost to their applications. In this paper, we studied the effect of curvature radius on optical characteristics of convex FLS. For this purpose the properties of a cylindrical OLED as an FLS were studied theoretically and experimentally. The most fundamental characteristic of a FLS is the total luminous flux, the radiation pattern and the spectrum. Two OLED samples with barrier layer thickness of 100 nm and 150 nm were fabricated and their characteristics were measured at curvature radii of R0=∞ mm (flat), R2=143mm (curved) and R5=56.7 mm (curved). Furthermore, the measurement field contours were calculated for non‐tilted and tilted flat planes, and on inner and outer surfaces of a cylindrical FLS. Finally, the metrology issues of the curved FLS were discussed.

Metrological advances in reference measurement procedures for electrolytic conductivity

The Working Group on Electrochemical Analysis and Classical Chemical Methods (EAWG) of the Consultative Committee for Amount of Substance: Metrology in Chemistry and Biology conducts regular pilot studies and key comparisons to ensure international consistency of electric conductivity measurement results of electrolyte solutions with an uncertainty of around 0.02% at the highest level. Apart from supporting the international calibration infrastructure, comparison measurements have also been used to investigate specific metrological issues related to conductivity measurements which will be reviewed in this paper. First, two different metrological references coexist for conductivity measurements, namely the SI and recipe-based primary conductivity standards, the implications of which will be discussed. Furthermore, pilot study P142 and subsequent investigations by an EAWG expert group have revealed significant inconsistencies in the equivalence of conductance ratios. Such conductance ratios are the basis for assigning conductivity values to secondary standards and conductivity measurements in the field. The activities of the EAWG to investigate this fundamental issue will be reviewed. Finally, the metrological support for conductivity measurements of new kinds of conductivity standards will be outlined.

Silver-based plasmonics: golden material platform and application challenges [Invited

A novel material platform based on metallic thin films with ultra-low losses in the visible and near-IR range is crucial for rapid development of a wide range of new generation plasmonic devices. For many years silver has been known as potentially the best plasmonic material with the naturally lowest ohmic losses at optical frequencies. However, the widespread implementation of the silver-based material platform for plasmonics and metamaterials is limited due to technological challenges in thin film synthesis and nanoscale features fabrication techniques. This review describes the main types of silver-based plasmonic devices from the thin films point of view required for their widespread practical application. Based on comparative analysis of more than 60-year-long history of previously reported data for the silver thin films, the authors formulate the qualitative and quantitative criteria of ideal silver film (which the authors name the silver dream plasmonic film) for plasmonic devices with ultra-low loss. This paper outlines on several well-known metrology issues in plasmonic metallic films characterization and summarize the set of methods for their properties careful and precise extraction. Finally, the detailed analysis of silver synthesis techniques and quantitative comparison of the achieved silver properties is carried out.