International Round Robin Test Research Articles

International Round-Robin Test of Critical Current of Superconducting Cable Sample

International Round-Robin Test of Critical Current of Superconducting Cable Sample

A practical stress-based test method for evaluating reversible stress limit for critical current degradation in rare-earth barium copper oxide (REBCO) tapes.

The superior electromechanical properties of second-generation high-temperature superconducting rare-earth barium copper oxide (REBCO) coated conductor tapes make them viable candidates for high magnetic field applications. To characterize their electromechanical properties (EMPs) under operating conditions, the critical current degradation behavior of the REBCO tapes should be evaluated. Conventional evaluation methods for EMPs usually rely on a strain-based test method that utilizes an extensometer to measure the deformation induced on the coated conductor tape. This study aims to establish a practical stress-based test method that determines the reversible stress limit for critical current (Ic) degradation in REBCO tapes without using extensometers under uniaxial tension. For an efficient test procedure, Ic measurements were initially performed with broad stress intervals and then changed to narrow stress intervals before the critical current degraded irreversibly. Four commercially available REBCO tape samples were used to validate the reliability of the proposed stress-based test method. It was then assessed by comparing them with those obtained using the conventional strain-based test method. Statistical estimations were used to determine the reproducibility of the results. These results provide a basis for an international round-robin test guideline to establish a test method for measuring the electromechanical properties of high-temperature superconducting tapes at cryogenic temperatures.

Repeatability of the European Standardized Method for Measuring Sound Reflection and Sound Insulation of Noise Barriers

The EN 1793-5 and EN 1793-6 standards have been in use for many years as a method for measuring the intrinsic characteristics of noise barriers installed along highways and railways. They require a sound source and a grid of microphones, to be placed near the barrier and in free field conditions, according to predetermined distances. In principle, small errors in positioning the sound source and microphone grid may affect the results obtained. An international round-robin test was carried out in 2012 to evaluate the repeatability and reproducibility of the method, but until now no studies have been carried out to evaluate and compare the repeatability of laboratory versus in-place measurements performed with the same equipment and its variance when an imperfect positioning of sound source and microphones is taken into account. In the present work, multiple series of sound reflection index and sound insulation index measurements performed on noise barriers of the same kind installed in the laboratory or along a highway are presented. The measurements were repeated in different ways: (1) in the laboratory, leaving the source and microphones unmoved to assess the repeatability of the results and of the measurement system under controlled conditions; (2) in the laboratory, repositioning for each measurement the source and microphone grid to assess the robustness of the method under real conditions but in a controlled environment; (3) in situ, along a highway open to traffic, repositioning for each measurement the source and microphone grid to assess the repeatability of the method under real conditions in a critical environment. In both reflection index and sound insulation index measurements, the standard deviation on single-number ratings in all cases examined is well below the value presented in EN 1793-5 and EN 1793-6, which was obtained from statistical analysis of the international round-robin test performed a dozen years ago, suggesting that expert operators with state-of-the art equipment can achieve much better results now.

Marine propeller underwater radiated noise prediction with the FWH acoustic analogy Part 1: Assessment of model scale propeller hydroacoustic performance under uniform and inclined flow conditions

This paper explores hydrodynamic performance, including cavitation and URN for the benchmark model scale propeller, The Princess Royal, operating under uniform and inclined flow conditions. In the numerical calculations, the DES method and the k-ω SST turbulence model were utilised to solve the cavitating flow around the propeller and determine the source field for the sound propagation. Also, the developed V-AMR advanced meshing technique was applied for accurately solving the tip vortex flow and hence better representation of the tip vortex cavitation in the propeller slipstream. The Schnerr-Sauer mass transfer model was used to model the cavitation on and off the propeller blades, whereas the cavitating propeller URN was predicted using the permeable formulation of the FWH equation. The numerical results were first validated with the available experimental data in model scale in a wide range of operating conditions through the propeller hydrodynamic performance characteristics, cavitation extensions and URN. Then, the numerical URN predictions were extrapolated to full-scale with the aid of the ITTC procedure to compare the CFD predictions with the extrapolated measured data obtained by different testing facilities within the scope of a recently conducted international round-robin test campaign. The results showed that the sheet and tip vortex cavitation was generally modelled successfully in the numerical calculations compared to the model-scale experimental observations in different facilities. The propeller URN predictions were in good agreement with the measured data in model scale, although some URN level discrepancies (i.e., around 5 and 10 dB) were observed between numerical predictions and model-scale measurements at certain frequencies in the low-frequency region of the noise spectrum. By taking the URN level differences measured in each facility into account, the full-scale extrapolated propeller URN predictions satisfactorily agree with the extrapolated full-scale experimental test data. Therefore, this study confirms that the CFD methods, together with the acoustic analogy, can be used for predicting the propeller URN, similar to other traditional ship hydrodynamic phenomena (e.g., resistance, self-propulsion, cavitation etc.).

Critical view of the results of the 2nd international round-robin test on EIS measurements of organic coatings

Although electrochemical impedance spectroscopy (EIS) is a well-established and powerful technique to investigate protective properties of organic coatings, there is no comparative study to show how reliable and reproducible are the results of this technique between different laboratories. One of the tools to fill this gap is international round robin tests (RRT). Following up the conclusions of 1st international RRT, presented in 11th workshop on AETOC Valencia (Spain), this paper will present the results of 2nd international RRT. 30 laboratories have participated this RRT using various equipment (24 different electrochemical systems from 8 manufacturers). To reduce the complexity of the testing in the 2nd RRT only one well defined E-coating material on a single kind of substrate (steel) was used as sample for all participating labs.Results were analyzed in terms of estimated capacitance (RC model, at single frequencies at 1 kHz and 10 kHz, respectively) and magnitude of impedance at low frequencies (100 mHz and 10 mHz). The provided data has been evaluated in a balanced approach using equal statistical weighting for each laboratory. The general conclusion drawn from the tests performed with the coated panel is that the results in terms of repeatability and reproducibility are scattered (high variance). To understand this issue, an additional RRT was organized with 11 participating laboratories (which showed the best results in the E-coating test), using a dummy cell as a test subject. Scattered EIS Bode plots for E-coting as well as for the dummy cell were observed and will be discussed.Although the careful collection and evaluation of the EIS raw data is crucial, it became apparent that this is not always being done. The observed sources of error and measurement artifacts will be presented and discussed. Recommendations for best lab and best evaluation practices will be presented.

Optimization strategies for the German version of the soundscape affective quality instrument

Semantic differences in the soundscape circumplex instrument may have an impact on affective quality assessments of acoustic environments, hampering comparison in cross-cultural settings. Although an adopted version of the ISO/TS 12913-2 exists in Germany, it has not yet been sufficiently validated. In a listening experiment conducted as part of an international round-robin test, a total of 27 soundscapes were evaluated using alternate German translations of the English instrument. Results from two different optimiziation strategies were compared: (1) maximized circumplexity of the German scale version and (2) language invariance between German and English scale versions. Confirmatory factor analyses and invariance testing were employed to determine optimal translations and calculate resulting goodness of fit. Results demonstrate that strategy 1, with two new item translations, yields better results in terms of circumplexity and language invariance than the current DIN ISO/TS 12913-2 version. However, to allow fully unbiased cross-cultural comparisons of soundscape impressions, drawing on the instrument developed with strategy 2 is more suitable, since it produces scores strictly corresponding to those of the English scale. As the analysis demonstrates, this seemingly paradox finding results from a lack of empirical circumplexity of the English original.

International round robin test of environmentally benign lubricants for cold forging

The use of lubricants without conversion layers is a global target of the cold forging industry. Compared to conventional lubricant systems based on zinc phosphate coatings, these fluctuate more in their tribological properties. In a worldwide round robin test, thirteen different lubricants were compared in tests with six different tribometers. The results show significant differences in friction coefficients both between different lubricants and between tribometers. A multiple regression model describing the dependence of the coefficient of friction on tribological loads allows for a consistent merging of the data. The model is successfully validated by a full-forward extrusion process.

Establishment of the standard method of magnetostriction measurement of grain-oriented electrical steel strip and sheet

Standard method of magnetostriction measurement of grain-oriented electrical steel strip and sheet by means of a single sheet tester and an optical sensor was established as IEC 60404-17 Ed.1 [1] by the IEC/TC68 after intense considerations among magnetostriction experts. A new idea called “bridge” was introduced in order to minimize effects due to mechanical factors and other improvements were made. The 4th international round robin test (RRT) was carried out in 2020 and it was confirmed that the measurement reproducibility of the peak-to-peak value of magnetostriction improved from 5% or less in the 3rd RRT to 2% or less.

1st international round robin test on safety characteristics of hybrid mixtures

There is no applicable existing standard for the determination of safety characteristics for hybrid mixtures. While developing a new standard in a joint research project in Germany first results from parameter studies led to a standard procedure that can be adopted by laboratories that are already testing dusts in the so called 20L-sphere with as little additional effort as necessary. In fact, one of the main objectives of this research project was to keep modifications and adjustments from the generally accepted dust testing procedures as easy and minimal as possible so as to limit potential deviations from one laboratory to another.In this first round robin test on hybrid mixtures ever, with methane as gas component and a specific corn starch as dust sample, the practicality of the whole procedure, the scattering of the results and the deviation between the testing apparatuses is investigated. This paper summarizes the experimental procedure adopted and objectives of the first round-robin phase involving three of the four original German companies, plus volunteering laboratories from Australia, Belgium, Czech Republic, France, Poland and P.R. China. The results will have an impact on the new standard and may lead to robust data for later simulation purposes.

Optimisation of the uncertainty of oil spill identification from replicate comparative analyses: Comparison of standardised and novel identification methods

Oil spill identifications involve the comparison of oil fingerprints between the oil spill and suspected oil sources, defined by ratios between the abundances of oil-discriminating compounds, Diagnostic Ratios (DR). The normalised Nordtest and EN 15522-2 methodologies use Student's t statistic (S-t) or a maximum relative difference (SC) to compare mean DR from replicate sample analysis. While the S-t method assumes the normality of DR distribution, the SC method is based on controlled DR dispersion. However, when false, the assumptions and approximations adopted can lead to low true identification rates. This work presents a novel computational tool for the statistically sound oil spill identification that allows following requirements defined by EN 15522–2, the comparison of replicate DR determinations, and the use of different DR sets and formats. The tool uses the Monte Carlo Method (MCM) to describe the probability distribution of the difference of mean DR, allowing estimating the probability of the true acceptance of fingerprints equivalence. The studied methods were applied to the comparison of signals from the same oil and to a real scenario reproduced in an International Round Robin Test. The methods were compared considering the probabilities of true acceptance of oil patterns equivalence based on a single, γ, or various, δ, DR. The MCM method performs identifications with γ equivalent to the defined confidence level for the comparison, P. Since the various DR studied are not perfectly correlated, the δ is below P. The number of replicate analyses performed and the DR considered in the comparison affect identification performance. The S-t produces comparison criteria with a γ lower than P. The SC criteria for duplicate analysis is associated with a δ lower than the obtained by the MCM. A user-friendly MS-Excel spreadsheet is available to perform oil pattern comparisons using various methods and conditions.

China’s participation in the international RRT for Ic measurement of superconducting cables organized by IEC/TC90

Currently, IEC/TC90 is working on standardizing the method for measuring critical current ( I c ) in superconducting cables. At the end of 2020, an international round robin test (RRT) was organized, in which five Chinese institutions participated, and four accomplished the test. The electric-field versus current ( E - I ) curves obtained by each institution are highly repeatable. Those obtained by different institutions are nearly identical after appropriate curve averaging, indicating high reproducibility, except the last participant's inner core curves. The discrepancy was later determined to be the result of sample cable damage. After excluding highly deviated data, it is determined that the maximum relative standard uncertainty in I c is 0.7%, and the maximum relative standard uncertainty in n -value is 12.8%. The I c values are comparable to Japan's domestic RRT results, but the n -values are significantly different. The test results support the DC four-terminal method as a recommended test method, with a target relative uncertainty of less than 2% for the I c value.

International Round Robin Test of Thermoelectric Generator Modules.

The status of metrology for the characterization of thermoelectric generator modules (TEM) is investigated in this work by an international round robin (RR) test including twelve laboratories from nine countries on three continents. Measurements have been performed with three samples of a Bi2Te3-based commercial TEM type, which has prevailed over three competing types during previous tests on the short- and long-term stability. A comparison of temperature-dependent results is provided up to 200 °C hot side temperature for the maximum power output Pmax, the incident heat flow (at maximum efficiency conditions), and the maximum efficiency ηmax. Data evaluation from all RR participants reveals maximum standard deviations for these measurands of 27.2% (Pmax), 59.2% (), and 25.9% (ηmax). A comparison between RR data sets and reference data from manufacturer specifications shows high deviations of up to 46%, too. These deviations reflect the absence of measurement guidelines and reference samples and confirm the need for improvements in the standardization of TEM metrology. Accordingly, the results of the RR are presented against the background of our own investigations on the uncertainty budgets for the determination of the abovementioned TEM properties using inhouse-developed characterization facilities, which comprise reference and absolute measurement techniques for the determination of heat flow.

The international round robin test of magnetostriction measurement of grain-oriented electrical steel by means of a single sheet tester and an optical sensor

This paper reports the results of the round robin test (hereafter RRT) of magnetostriction measurement using the test apparatus following IEC 60404-17 from April 2019 to August 2019. The main purpose of the RRT is to identify factors affecting the magnetostriction measurement, and then to estimate the reproducibility of the measurements. Nine anonymous laboratories, whose test apparatuses are a little different from the draft standard, participated in the RRT. In the progress of the RRT, we identified factors affecting the magnetostriction measurement. Finally, the reproducibility of the measurements was estimated. Doshisha Univ. acts as the reference laboratory.

A standardized biohydrogen potential protocol: An international round robin test approach

Hydrogen production by dark fermentation is an emerging technology of increasing interest due to its renewable feature. Recent scientific advances have well investigated the operational conditions to produce hydrogen through the valorization of several wastes or wastewaters. However, the development of standardized protocols to accurately assess the biohydrogen potential (BHP) is of crucial importance. This work is the first interlaboratory and international effort to validate a protocol estimating hydrogen potential using batch tests, using glucose as individual model substrate. The repeatability of the hydrogen potential (HP) increased with variations of the proposed protocol: reducing substrate concentration, increasing the buffer capacity, and using an automatic device. The interlaboratory variation of the HP was reduced from 32 to 12%, demonstrating the reproducibility and robustness of the proposed protocol. Recommendations to run BHP tests were formulated in terms of i) repeatability and reproducibility of results, ii) criteria for results validation and acceptance, iii) workload of the proposed protocols.

Analysis of Elemental Composition of Fe1−xNix and Si1−xGex Alloy Thin Films by EPMA and μ-XRF

The present study reports on measurements on thin Fe-Ni films on silicon and first-time results of analysis on Si-Ge thin films deposited on a non-conductive aluminium oxide Substrate by electron probe microanalysis (EPMA). Standard-based and standardless EPMA (with EDS) results were used in combination with the thin film analysis software Stratagem for the quantification. Further, X-ray fluorescence analysis (XRF) can be used for the determination of elemental composition and thickness of such films as well. In this case, XRF with a μ-focus X-ray source (μ-XRF) attached to a SEM was applied. For quantification, a fundamental parameter (FP) approach has been used to calculate standard-based and standardless results. Both thin film systems have been chosen as samples of an international round robin test (RRT) organised in the frame of standardisation technical committee ISO/TC 201 ‘Surface chemical analysis’, under the lead of KRISS. The main objective of the RRT is to compare the results of atomic fractions of Fe1-xNix and Si1-xGex alloy films obtained by different surface Analysis techniques, such as X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES), and secondary ion mass spectrometry (SIMS) applied in the depth-profiling operation mode. Five samples of different atomic fractions of each thin film system, i.e., Fe1-xNix and Si1-xGex, have been grown by ion beam sputter deposition on silicon and Al2O3 wafers, respectively. Reference FeNi and SiGe films with well-known elemental composition and thickness have been also supplied for standard-based analysis. An excellent agreement has been obtained between the atomic fractions determined by EPMA and µ-XRF with the KRISS certified values.zeige mehr

Interdisciplinary Round-Robin Test on Molecular Spectroscopy of the U(VI) Acetate System.

A comprehensive molecular analysis of a simple aqueous complexing system—U(VI) acetate—selected to be independently investigated by various spectroscopic (vibrational, luminescence, X-ray absorption, and nuclear magnetic resonance spectroscopy) and quantum chemical methods was achieved by an international round-robin test (RRT). Twenty laboratories from six different countries with a focus on actinide or geochemical research participated and contributed to this scientific endeavor. The outcomes of this RRT were considered on two levels of complexity: first, within each technical discipline, conformities as well as discrepancies of the results and their sources were evaluated. The raw data from the different experimental approaches were found to be generally consistent. In particular, for complex setups such as accelerator-based X-ray absorption spectroscopy, the agreement between the raw data was high. By contrast, luminescence spectroscopic data turned out to be strongly related to the chosen acquisition parameters. Second, the potentials and limitations of coupling various spectroscopic and theoretical approaches for the comprehensive study of actinide molecular complexes were assessed. Previous spectroscopic data from the literature were revised and the benchmark data on the U(VI) acetate system provided an unambiguous molecular interpretation based on the correlation of spectroscopic and theoretical results. The multimethodologic approach and the conclusions drawn address not only important aspects of actinide spectroscopy but particularly general aspects of modern molecular analytical chemistry.

International Round Robin Test for Critical Current Measurement of RE-Ba-Cu-O Superconducting Tapes

VAMAS TWA 16 promoted an international round robin test (RRT) on critical current (I c ) measurement of RE-BaCu-O (REBCO; RE = rare earth) superconductors to establish the transport I c measurement method in liquid nitrogen bath without an external magnetic field. Ten laboratories from five countries participated in the RRT and tested commercially available REBCO superconductors. I c and measurement conditions were reported. In parallel, intrinsic I c nonuniformity of the superconductors were evaluated by reel-to-reel scanning Hall-probe microscopy for 10-m conductors. Statistical analyses of I c provided uncertainty of the measurement method. Combined standard uncertainty was analyzed considering the intrinsic nonuniformity of I c . The analysis indicated that the intrinsic nonuniformity has the largest contribution to the uncertainty of I c .

Round‐robin test for the measurement of layer thickness of multilayer films by secondary ion mass spectrometry depth profiling

An international round‐robin test (RRT) was performed to investigate a method to determine the interface location and the layer thickness of multilayer films by secondary ion mass spectrometry (SIMS) depth profiling as a preliminary study to develop a new work item proposal in ISO/TC‐201. Two types of reference materials were used in this RRT. A SiGe alloy (Si52.4Ge47.6) reference film was used to determine the relative sensitivity factors of Si and Ge. A Si/Ge multilayer reference film was used to determine the relative sputtering rates of the Si and Ge layers. The layer thicknesses were measured from the interfaces determined by a 50 atomic percent definition. Seven laboratories from 5 countries participated in this international RRT. The RRT reference expanded uncertainties for Si and Ge layers in a Si/Ge multilayer with similar thicknesses as the reference film were 0.76 and 1.17 nm, respectively. However, those in a thinner Si/Ge multilayer film were slightly larger at 1.04 and 1.59 nm, respectively. Most of the thickness ratios in the 2 Si/Ge multilayer films were consistent with the RRT reference value within their expanded uncertainties.

Iron Disilicide as High-Temperature Reference Material for Traceable Measurements of Seebeck Coefficient Between 300 K and 800 K

Thermoelectric generators (TEGs) convert heat to electrical energy by means of the Seebeck effect. The Seebeck coefficient is a central thermoelectric material property, measuring the magnitude of the thermovoltage generated in response to a temperature difference across a thermoelectric material. Precise determination of the Seebeck coefficient provides the basis for reliable performance assessment in materials development in the field of thermoelectrics. For several reasons, measurement uncertainties of up to 14% can often be observed in interlaboratory comparisons of temperature-dependent Seebeck coefficient or in error analyses on currently employed instruments. This is still too high for an industrial benchmark and insufficient for many scientific investigations and technological developments. The TESt (thermoelectric standardization) project was launched in 2011, funded by the German Federal Ministry of Education and Research (BMBF), to reduce measurement uncertainties, engineer traceable and precise thermoelectric measurement techniques for materials and TEGs, and develop reference materials (RMs) for temperature-dependent determination of the Seebeck coefficient. We report herein the successful development and qualification of cobalt-doped β-iron disilicide (β-Fe0.95Co0.05Si2) as a RM for high-temperature thermoelectric metrology. A brief survey on technological processes for manufacturing and machining of samples is presented. Focus is placed on metrological qualification of the iron disilicide, results of an international round-robin test, and final certification as a reference material in accordance with ISO-Guide 35 and the “Guide to the expression of uncertainty in measurement” by the Physikalisch-Technische Bundesanstalt, the national metrology institute of Germany.

Study on Standard Measurement Method of Magnetic Property of Fe-Based Amorphous Strip—Round Robin Test Results

In order to establish a standard measurement method for Fe-based amorphous strip, an amorphous single-sheet tester (AM-SST) has been investigated. An international round robin test (RRT) was carried out among International Electrotechnical Commission (IEC)/TC68 experts in 2014. The AM-SST based on the proposed standard measurement method was built and investigated for its adoption by IEC. In this paper, the outline and the results of the RRT are reported. The repeatability of specific total loss with $H$ coil and magnetizing current methods by using the AM-SST proposed is shown.