Round Robin Test Research Articles

National round robin test (RRT) for delamination strength testing YBCO HTS wires at room temperature (RT) and 77K

Second generation high temperature superconducting coated conductors (2G HTS CCs) have become indispensable wires for high-field superconducting magnets. The transverse mechanical delamination strength (MDS) is a key parameter due to the multilayer structure of CCs. Determination of the MDS value is thus significant. In this study, we report the MDS results of national round robin test (RRT) conducted in china by the institutions of Lanzhou University, Institute of Plasma Physic, and Shanghai Superconductor Technology Co., Ltd at room temperature (RT) and 77 K, respectively, for the determination of 2G HTS CCs (copper-stabilized) transverse MDS by a standardized procedure. Data at RT and 77 K all showed good consistency, with the relative standard uncertainty of 2.22% and 2.35%, respectively, illustrating the reliability of the established procedure, which can be used as a reference for engineering CC manufacturing and design of application magnets.

Validation of a Qualification Procedure Applied to the Verification of Partial Discharge Analysers Used for HVDC or HVAC Networks

The insulation condition of HVDC grids consisting of cable systems, GIS, and converters should be monitored by partial discharge (PD) analysers using artificial intelligence (AI) tools for efficient insulation diagnosis. Although there are many experiences of PD monitoring solutions developed for the supervision of the insulation condition of HVAC grids using PD analysers, there are no standardised requirements for their qualification available yet. The international technical specification TS IEC 62478 provides general rules for PD measurements using electromagnetic methods but does not define performance requirements for qualification tests. HVDC and HVAC PD analysers must be tested by unambiguous test procedures. This paper compiles experiences of using PD analysers with HFCT sensors in HVAC grids (cable systems, GIS, and AIS) to define a qualification procedure for HVAC systems. This procedure is applicable to HVDC grids (cable systems, GIS, AIS, and converters) because the particularities related to the insulation behaviour under HVDC voltage are also considered. Representative PD sources are discussed in HVAC and HVDC positive and negative polarity. The PD pulse trend of representative insulation defects in HVDC cable systems is quite different from that of HVAC grids. Special attention should be paid to the acquisition of PD signals in HVDC grids since few pulses appear in solid insulations, mainly during voltage changes (polarity reversals or surges), but rarely in continuous operation with constant direct voltage. A synthetic PD simulator has been developed to reproduce trains of PD pulses or noise signals, similar to those that can appear in the power network. A set of three functionality tests has been developed for qualification of the diagnostic capabilities of PD analysers working up to 30 MHz addressed to HVDC or HVAC grids: (1) PD recognition test, (2) PD clustering test, and (3) PD location test. This qualification procedure has been validated by means of a round-robin test performed by five research institutes (RISE, FFII, TUDelft, TAU, and UPM) using commercial and in-development AI PD recognition and clustering tools to demonstrate its robustness and applicability. Applying this qualification procedure, two PD methods for electrical detection and prevention of insulation defects have been approved, one for HVAC and the other for HVDC grids.

Metrological Qualification of PD Analysers for Insulation Diagnosis of HVDC and HVAC Grids.

On-site partial discharge (PD) measurements have turned out to be a very efficient technique for determining the insulation condition in high-voltage electrical grids (AIS, cable systems, GIS, HVDC converters, etc.); however, there is not any standardised procedure for determining the performances of PD measuring systems. In on-line and on-site PD measurements, high-frequency current transformers (HFCTs) are commonly used as sensors as they allow for monitoring over long distances in high-voltage installations. To ensure the required performances, a metrological qualification of the PD analysers by applying an evaluation procedure is necessary. A novel evaluation procedure was established to specify the quantities to be measured (electrical charge and PD repetition rate) and to describe the evaluation tests considering the measured influence parameters: noise, charge amplitude, pulse width and time interval between consecutive pulses. This procedure was applied to different types of PD analysers used for off-line measurements, sporadic on-line measurements and continuous PD monitoring. The procedure was validated in a round-robin test involving two metrological institutes (RISE from Sweden and FFII from Spain) and three universities (TUDelft from the Netherlands, TAU from Finland and UPM from Spain). With this round-robin test, the effectiveness of the proposed qualification procedure for discriminating between efficient and inappropriate PD analysers was demonstrated. Furthermore, it was shown that the PD charge quantity can be properly determined for on-line measurements and continuous monitoring by integrating the pulse signals acquired with HFCT sensors. In this case, these sensors must have a flat frequency spectrum in the range between several tens of kHz and at least two tens of MHz, where the frequency pulse content is more significant. The proposed qualification procedure can be useful for improving the future versions of the technical specification TS IEC 62478 and the standard IEC 60270.

Round Robin Tests for WWER Heat Exchange Tubes

One of the most affected components from the point of view of long-time operation of WWER reactors are heat exchanging tubes of steam generators. With the nominal tube wall thickness of 1,4 mm (WWER440) or 1,5 mm (WWER1000) only and significant consequences of many factors, such as; increasing units power output, the long-time operation, secondary water chemistry and, in some cases, mechanical impact due to dissimilar welds (DN1100) repair, steam generator tubing represents one of the most critical component significantly limiting overall lifetime of many units. New forms of degradations came into being in many of WWER unites, many of them specific for some units only. Therefore, there is a wide accepted need for applying new inspection techniques. As such, these techniques are now on the market, being partially used in some units. Pulled-out tubes from Jaslovske Bohunice units 1 and 2, with real defects, well documented from the point of view of historical eddy current results and results from last inspection, carefully stored and treated, provide the great opportunity for experimental verification of these new, state-of-the art inspection ET techniques (e.g., MRPC, X-Probe, High-speed MRPC etc.).

Round-robin testing for LMO2 and MYC as immunohistochemical markers to screen MYC rearrangements in aggressive large B-cell lymphoma

Aggressive large B-cell lymphomas (aLBCL) include a heterogeneous group of lymphomas with diverse biological features. One of the approaches to the diagnosis of aLBCL is based on the identification of MYC rearrangements (MYC-R), in addition to BCL2 and BCL6 rearrangements by genetic techniques, mainly fluorescent in situ hybridization (FISH). Because of the low incidence of MYC-R, the identification of useful immunohistochemistry markers to select cases for MYC FISH testing may be useful in daily practice. In a previous work, we identified a strong association between the profile CD10 positive/LMO2 negative expression and the presence of MYC-R in aLBCL and obtained good intralaboratory reproducibility. In this study, we wanted to evaluate external reproducibility. To evaluate whether LMO2 can be a reproducible marker between observers 50 aLBCL cases were circulated among 7 hematopathologists of 5 hospitals. Fleiss’ kappa index for LMO2 and MYC were 0.87 and 0.70, respectively, indicating high agreement between observers. In addition, during 2021–2022, the enrolled centers included LMO2 in their diagnostic panels to evaluate prospectively the utility of the marker, and 213 cases were analyzed. Comparing LMO2 with MYC, the group of CD10 positive cases showed higher specificity (86% vs 79%), positive predictive value (66% vs 58%), likelihood positive value (5.47 vs 3.78), and accuracy (83% vs 79%), whereas the negative predictive values remained similar (90% vs 91%). These findings place LMO2 as a useful and reproducible marker to screen MYC-R in aLBCL.

Machine learning for the classification of macroscale fracture surfaces

Abstract The characterization of fractographic surfaces typically requires experts to evaluate the characteristics of fracture surfaces. However, these evaluations are influenced by human factors, such as subjectivity, and suffer from a lack of reproducibility. In this context, machine learning (ML), which has been established in various disciplines within materials science over the past few years, is a promising field enabling a more objective and reproducible evaluation. This study will evaluate the use of ML for the evaluation of fracture surfaces of notched Charpy specimens based on digital camera images. Image sections of the two reference regions “upper shelf” (ductile) and “lower shelf” (brittle) will serve as the database. In a first step, data visualization will be performed and data separability will be verified using unsupervised ML. On this basis, supervised ML will be used to train models to distinguish brittle and ductile fractures. These models will then be applied to determine ductile und brittle portions in mixed fracture modes, with the results being in good agreement with the expert consensus achieved in the round robin test.

Optical Characterization of Al Island Films: A Round Robin Test

The determination of the effective optical constants of metal island films is an essential step towards the practical incorporation of this kind of films in optical coatings. In this work, the optical properties of aluminium island films deposited by electron beam evaporation on quartz substrates are investigated using different approaches employed by three research groups. The effective optical constants of the island films are inferred from optical measurements (spectrophotometry and spectroscopic ellipsometry) using: (i) a parameter-free dispersion model, (ii) a multiple oscillator model based on Gaussian line-shapes and (iii) the β distributed oscillator model. All the used approaches provide similar physical insights, i.e., an increase in the effective thickness of the metal island film, a red-shift and broadening of the plasmon resonance and an enhancement of the infrared absorption as the amount of deposited material increases. However, the optimal values of the effective optical constants and thickness significantly depend on the employed model and the experimental data used for data fitting.

RILEM TC 266-MRP: round-robin rheological tests on high performance mortar and concrete with adapted rheology—a comprehensive flow curve analysis

RILEM TC 266-MRP: round-robin rheological tests on high performance mortar and concrete with adapted rheology—a comprehensive flow curve analysis

A uniform method for the characterization of shear fracture strain for high-strength steel sheets under quasi-static and crash loading

In the conflict between lightweight design and crash safety of high-strength steel components failure models for crash simulation have to be calibrated precisely. To predict shear failure strains in a wide strain rate range shear experiments must be performed from quasi-static up to crash-relevant strain rates of about 100 s-1. In particular, asymmetric notched shear tensile specimens have proven useful for this purpose in previous investigations. Using this type of shear specimen, a characterization concept for shear loading in a wide strain rate range is presented for high strength steel sheets of different strength, ductility and sheet thickness in this contribution. Within a round robin test of different laboratories the influence of the degrees of freedom in the clamping area and the free clamping length on the kinematic of the specimens and on the deformation and failure behavior in the shear zone are investigated in detail. The main outcome is that the disadvantages of a fix clamping in terms of shear deformation, shear fracture and homogeneity of the shear zone can be compensated by a large free clamping length. An evaluation method based on digital image correlation (DIC) is presented, which enables an operator- and laboratory-independent determination of shear strains up to failure.

Recommendation of RILEM TC 271-ASC: New accelerated test procedure for the assessment of resistance of natural stone and fired-clay brick units against salt crystallization

This recommendation is devoted to testing the resistance of natural stone and fired-clay brick units against salt crystallization. The procedure was developed by the RILEM TC 271-ASC to evaluate the durability of porous building materials against salt crystallization through a laboratory method that allows for accelerated testing without compromising the reliability of the results. The new procedure is designed to replicate salt damage caused by crystallization near the surface of materials as a result of capillary transport and evaporation. A new approach is proposed that considers the presence of two stages in the salt crystallization test. In the first, the accumulation stage, salts gradually accumulate on or near the surface of the material due to evaporation. In the second, the propagation stage, damage initiates and develops due to changes in moisture content and relative humidity that trigger salt dissolution and crystallization cycles. To achieve this, two types of salt were tested, namely sodium chloride and sodium sulphate, with each salt tested separately. A methodology for assessing the salt-induced damage is proposed, which includes visual and photographical observations and measurement of material loss. The procedure has been preliminarily validated in round robin tests.

Round-Robin test for the histological diagnosis of acute colonic Graft-versus-Host disease validating established histological criteria and grading systems

Histomorpholgy is one of the mainstays of acute Graft-versus-host disease (GvHD) diagnosis. However, concerns about reproducibility and the most appropriate grading system question its usefulness. Our aim was to assess histomorphological parameters and previously reported grading systems for GvHD regarding reproducibility and validity. Moreover, we propose that sum scores, derived by combining separately scored morphological parameters into a total score, might provide a simplified but equally effective means to grade GvHD. A total of 123 colon biopsies were assessed across four pathologists for intestinal GvHD using a Round-Robin test and results were correlated with clinical findings. Interobserver reproducibility was high for histological parameters that were evaluated as indicators of acute GvHD. Published grading systems were moderately reproducible (ICC 0.679–0.769) while simplified sum scores, in comparison, showed better interrater reliability (ICC 0.818–0.896). All grading systems and sum scores were associated with clinical signs of GvHD and in part with therapy response and survival. However, they were not able to stratify patients according to the clinical severity of GvHD. In a hot-spot analysis 1 crypt apoptotic body (CAB) in 10 crypts was a reasonable cut-off value for minimal diagnostic criteria of GvHD. In conclusion, histology can contribute to the diagnosis of GvHD and is reproducible. Published grading systems are able to reflect clinical findings as are simplified sum scores, which showed improved reproducibility and might be easier to handle as they are based on adding up histological parameters rather than transferring histological findings into a separate grading system. Sum scores will have to be further tested in a prospective setting.

The first total reflection X-ray fluorescence round-robin test of rat tissue samples: Preliminary results

The purpose of the study was performing a round-robin test for the element analysis of mammalian tissue samples using total reflection X-ray fluorescence (TXRF). To achieve this goal, the selected rat organs (kidney, heart, spleen and lung) were subjected to microwave digestion and, in the liquid form, were sent to four European laboratories participating in the inter-comparison investigation. There, using various commercially available TXRF spectrometers, their elemental composition was determined. The carried inter-laboratory comparisons involved macroelements with the concentration above 1000 μg/g (P, S and K) as well as microelements (Ca) and trace elements (Fe, Cu, Zn and Se) occurring, respectively, in the concentrations of 100–1000 μg/g and below 100 μg/g. The validation parameters such as the detection limits of the examined elements as well as the intra-day and inter-day precision were determined. To verify the variation in the results acquired in participating laboratories, for all measured elements, the inter-laboratory precision was evaluated. The data obtained by TXRF were also compared with the ones resulting from ICP-MS (Se) and ICP-OES analysis (P, S, K, Ca, Fe, Cu and Zn).The results obtained as part of the study confirmed the high usefulness of the TXRF method in the elemental analysis of animal tissues. As expected, the best results in terms of the examined validation parameters were obtained for elements with higher atomic numbers (Fe, Cu, Zn and Se). For these analytes, the round-robin test confirmed a good accuracy (around 100% for Fe, Cu, Zn) and precision (intra-day <6%, inter-day <12% and inter-laboratory <12%) what supports the use of TXRF for their determination in the mammalian tissue samples. The obtained results allowed, moreover, to indicate potential issues that require resolving in order to increase the usefulness of the method in case of the analysis of light elements such as P, S or K. It is worth mentioning here, inter alia, the improvement of the sample preparation procedures aiming at the reduction of self-absorption in its dried residue, optimization and/or unification of the sensitivity calibration and the spectra fitting procedures in particular laboratories.

RILEM TC 266-MRP: round-robin rheological tests on high performance mortar and concrete with adapted rheology—rheometers, mixtures and procedures

Recent developments in understanding the rheology of mortar and concrete as well as applying this understanding in the practice of construction necessitate an accurate assessment of materials’ rheological properties. It is well known that different rheometers for mortar and concrete deliver different results, as this was shown over 15 years ago in two measuring campaigns comparing concrete rheometers. Considering newly developed rheometers, including those to evaluate interface rheology and structural build-up at rest, as well as additional measurement procedures and data interpretation techniques, a new comparison campaign was carried out in 2018 at the Université d’Artois, in Bethune, France. This new campaign focused on measuring workability characteristics, flow curves, static yield stress values, interface properties and tribological data. A total of 14 different devices capable of measuring one or more of the above-mentioned characteristics were employed. These devices included four ICAR rheometers, the Viskomat XL, the eBT-V, the RheoCAD (two geometries), the 4SCC rheometer (two geometries), the plate test, the sliding pipe rheometer, a tribometer and an interface tool for the ICAR rheometer. This paper describes the mixture design and rationale of the five investigated concrete and three investigated mortar mixtures, design and analysis of the experiments, and comparison of test results. The findings confirmed some of the conclusions from two previous testing campaigns and expanded the findings to more modern concrete mixtures and more diversified sets of rheological devices. The investigated rheometers yielded different absolute values for material parameters, but they all were able to similarly distinguish between mixtures qualitatively. For static yield stress and interface rheology measurements, similar conclusions were obtained as for flow curves.

Potential and Limitations of Research Battery Cell Types for Electrochemical Data Acquisition

AbstractDeveloping new electrode materials and/or electrolytes for lithium‐ion batteries requires reliable electrochemical testing thereof. For this purpose, in academic research typically hand‐made coin‐type cells are assembled. Their advantage is a rather cheap and facile assembly, and possibility to prepare full‐cells as well as half‐cells, meaning cathode‐anode or electrode‐elemental lithium configurations. Critical parameters for testing data quality and the potential and limitations of cell tests in half‐cell configuration are discussed. Further, on the basis of a round robin test, using highly homogenous commercial electrodes, where graphite is used as anode and LiNi0.33Mn0.33Co0.33O2 (NMC111) as the cathode material, it is shown that data acquired is highly influenced by assembling parameters. Besides known variables such as the amount of electrolyte or electrode positioning, the proper height of the cell stack and the steel grade of the housing material are identified as decisive variables. Finally, it is demonstrated that under proper conditions coin cells can show a great cycle stability of &gt;2200 cycles using 1 C as dis‐/charge rate while retaining a capacity of 80 %. This performance is close to pouch‐type cells containing the same electrodes and electrolyte, which were used as a benchmark system and showed &gt;3500 cycles of lifetime.

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.

Validation of High School Experiments Using a Round Robin Test: Determination of the Explosiveness of Dusts

Experiments serve different purposes in chemistry education ranging from illustrating a certain subject matter to providing data for school-based research projects. When students use these experiments to collect data and draw conclusions, it is important that these experiments are valid. In this study, a new experiment for the determination of the explosiveness of dusts using a Low-cost-Hartmann apparatus (LC-HA) was developed for high school students. Which similarities and differences can be found between the data of developers and prospective users of the experiment? What is the added value of designing and applying a round robin test to a high school experiment? A round robin test including developers (n = 5) and prospective users (n = 54) is carried out. Data are collected from experiments with two different flour dust concentrations. Accuracy, precision, and variance are calculated for each group and compared between groups. There are similarities and differences between the data of both groups. For the lower concentration of flour dust, there are significant differences between the results of the two groups. For the higher concentration, there are no significant differences. Thus, carrying out a round robin test including both developers and prospective users benefits both groups. The developers gain insights into the application of their method. The prospective users receive information about their performance and the validity of their data. In the future, participation in round robin procedures should also be used as an opportunity to promote students’ knowledge about and skills for validation.

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.

Correlation analysis with measurement conditions and peak structures in XPS spectral round-robin tests on MnO powder sample

Spectral measurements provide valuable information on the electronic states and crystal structures of materials. In particular, X-ray photoelectron spectroscopy (XPS) can facilitate the analysis of the chemical-bond states of the surfaces of materials. In the analysis of XPS spectra, the spectrum to be measured is typically compared to a reference spectrum measured from a known single-phase sample. Therefore, establishing a reference spectral database is imperative. In this study, round-robin tests (RRT) of XPS spectra are performed to obtain recommended XPS reference spectra and develop appropriate measurement conditions, including preprocessing procedures. Determining the variations in peak structures between equipment- and sample-derived spectral shapes and quantitatively discussing them through RRT of XPS spectra are challenging. Therefore, an analysis method that automatically determines the above-mentioned variations and extracts the sample-derived common spectral structures is developed in this study. This paper presents a new approach to the quantitative analysis of round-robin XPS spectral tests. The required common peak structure, a new definition of the XPS reference spectrum, is obtained. Further, a correlation between the variability of deviations in the spectral data of the RRT and the measurement condition and XPS measurement equipment used is determined. Such a framework is essential for standardizing XPS spectra and expanding the XPS reference spectral database.

Repeatability in fan sound ratings: Challenges faced in a certification program

The Air Movement and Control Association International (AMCA International) maintains a certified ratings program for published air and sound performance for fans. Sound test results can come from AMCA 300 reverberant room testing but are also accepted from manufacturers’ accredited labs using other international test standards covering in-duct, enveloping surface, and sound intensity test methods. Observed repeatability between these test methods and labs will be discussed. AMCA 301 covers sound calculation methods, including extrapolation to non-tested sizes and speeds. Requirements and practical recommendations for this conversion will be discussed. Surveillance for the program comes through periodic check tests on manufacturers’ products. The check test process provides an overall view of measurement and calculation variance, as well as inevitable manufacturing tolerances and their impact on sound. Finally, the results of round robin testing conducted on centrifugal, tube axial, and vane axial fans at various accredited sound labs will be reviewed.