Round Robin Test Research Articles

Round‐robin test of all‐solid‐state battery with sulfide electrolyte assembly in coin‐type cell configuration

AbstractThe replacement of conventional lithium‐ion batteries with solid‐state batteries is currently under investigation by many players both from academia and industry. Sulfide‐based electrolytes are among the materials that are regarded as most promising, especially for application in the transport sector. The performance of anode, cathode, and solid electrolyte materials of this type of solid electrolyte is typically evaluated using manually assembled cells such as Swagelok cells, EL‐CELLs, and in‐house built pressure devices. Coin cells, however, are often disregarded. Though coin cells cannot accurately predict how a material will perform in an end‐use application battery cell format, they are easy to assemble and can provide reproducible data compared to the other cell types, which make them an interesting option for testing the materials under conditions more relevant for their envisioned application. The coin cell preparation method presented in this work has been evaluated interlaboratory for reproducibility and, in addition, can be modified depending on the optimization parameters of the solid electrolyte, cathode material, bilayer comprised on cathode and solid electrolyte, lithium metal anode, and cell in general. Besides, an interlab round‐robin test (RRT) is carried out between four laboratories, measuring defined electrochemical tests of sulfide solid‐state batteries in coin cell configuration. This RRT for the preparation of coin cell solid‐state batteries with sulfide solid electrolyte, lithium nickel manganese cobalt oxides cathode, and lithium metal anode is intended for academic researchers and provides guidelines of research in this field.

Measurement Method for Contact Wire Wear Based on Stereovision.

The contact wire wear is an important parameter to ensure the safety operation of electric railways. The contact wire may break if the wear is serious, which leads to transportation interruptions. This study proposes an optical measurement method of contact wire wear, using stereovision technology. The matching method of stereovision based on line-scan cameras is proposed. A lookup-table method is developed to exactly determine the image resolution caused by the contact wire being in different spatial positions. The wear width of the contact wire is extracted from catenaries' images, and the residual thickness of the contact wire is calculated. The method was verified by field tests. The round-robin tests of the residual thickness at the same location present excellent measurement repetitiveness. The maximum difference value between dynamic test results and ground measurement results is 0.13 mm. This research represents a potential way to implement condition-based maintenance for contact wire wear in the future in order to improve the maintenance efficiency and ensure the safety of catenary infrastructure.

Round Robin Test of Absorptance and Emittance of Particles for CSP

Precise knowledge of particle optical properties is crucial to the advancement and success of directly-irradiated particle receiver technologies. This work presents the results of a Round Robin Test (RRT) that was conducted between seven laboratories, where each participant measured the absorptance and emittance for a set of five different particle types. This research was performed within the framework of the SolarPACES Task III group, and the results helped establish a guideline for evaluating the optical properties of particles. The guideline was published on the SolarPACES Task III website in May 2022.

Precision of diamond turning sinusoidal structures as measurement standards used to assess topography fidelity

In optical surface metrology, it is crucial to assess the fidelity of the topography measuring signals. One parameter to quantify this is the small-scale fidelity limit T FIL defined in ISO 25 178-600:2019. To determine this parameter, sinusoidal structures are generated, where the wavelengths are modulated according to a discrete chirp series. The objects are produced by means of ultra-precision diamond face turning. Planar areas and regions with slopes below 4° could be produced with form deviations of ≲10 nm. An initial estimate of the cutting tool’s nose radius resulted in a deviation that caused the ridges of the structures to be too narrow by approximately 150 nm, while the trenches were too wide. At the bottom of narrow trenches, deviations are observed in the form of elevations with heights of about 20 to 100 nm. The measurement standard investigated in this study has also been used to characterise optical instruments in a round-robin test within the European project TracOptic, which requires precise knowledge of the geometry of all structures. The geometry of the topography, cosine structures superimposed with form deviations, was measured using the Met. LR-AFM metrological long-range atomic force microscope of the German National Metrology Institute.

In vitro bioaccessibility round robin testing for arsenic and lead in standard reference materials and soil samples.

In this study, we assessed the suitability of using a standard reference material (SRM) other than National Institute of Standards and Technology (NIST) 2710a or NIST 2711a in USEPA Method 1340 to determine arsenic (As) and lead (Pb) in vitro bioaccessibility (IVBA) and the capabilities of Canadian-based laboratories to perform the method. Five laboratories participated in an initial round robin study and analyzed NIST 2710a, NIST 2711a, BGS119, and Enviromat SS-2. Intra- and inter-laboratory variability were generally acceptable with percentage relative standard deviations (RSD) of less than 20%. The mean total As and Pb concentrations obtained for BGS119 (332 and 936 mg/kg, respectively) and the mean IVBA values (As = 14.3% and Pb = 78.1%) suggested it may be a suitable and acceptable SRM, whereas the concentration of As in Enviromat SS-2 as received (3.2 mg/kg) was deemed too low. Ten soil samples from sites with varying land use were analyzed in a follow-up round robin study using the modified IVBA method that included BGS119 as SRM. The concentrations of As and Pb in the IVBA extracts reported by the participating laboratories were comparable. The mean As IVBA values for the field-collected samples ranged from 0.1% to 56.4%; for Pb, they ranged from 7.0% to 121%. The lowest IVBA values were measured in mine site samples; the highest values were associated with smelter-affected soils. The low IVBA values correlated with high iron content. Intra- and interlaboratory reproducibility were acceptable (RSD < 30%). Based on the findings of the study, laboratories can use the modified method to provide reproducible and comparable As and Pb IVBA data. The use of BGS119 as an alternative SRM to assess contaminated sites in the province of British Columbia for regulatory purposes is recommended, as it is representative of As and Pb concentrations in contaminated soils in British Columbia. Integr Environ Assess Manag 2024;00:1-10. © 2024 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Reliability of VOC emission chamber testing – A round-robin test with a parquet adhesive, a parquet lacquer, and a levelling compound/Zuverlässigkeit von VOC-Emissionskammerprüfungen – Ein Ringversuch mit einem Parkettklebstoff, einem Parkettlack und einer Verlaufsspachtelmasse

The Association for the Control of Emissions in Products for Flooring Installation, Adhesives and Building Materials (GEV) organised a round-robin test in 2023 with the purpose to update its list of recommended testing laboratories based on test results. 39 laboratories from 11 countries tested the VOC emissions of 3 test products, a parquet adhesive, a parquet lacquer, and a levelling compound. The GEV round- robin test 2023 showed a similar variation of the test results as had been observed in previous round-robin tests in 2017 and 2020. The variation of the test results confirms the limited significance of single test results. This is why GEV discloses VOC emissions only in terms of broad emissions classes. The performance of 22 laboratories was rated by GEV to be good. Currently, a list of recommended testing laboratories for GEV emissions testing comprises 18 laboratories from 6 countries. These laboratories met the performance requirements of GEV in the round-robin test and presented an accreditation of this testing protocol according to ISO/IEC 17025.

Reproducibility assessment of an emulator-type load-based testing methodology

Current testing procedures for the performance rating of air conditioners (ACs) and heat pumps are conducted while maintaining the valve opening and compressor speed at fixed values, thus providing measurements that are often not representative of the actual field operation of these systems. The proposed emulator-type load-based testing methodology makes it possible to reproducibly test different units under various environmental and load conditions while maintaining the native control of the system active. This study presents and discusses the results of round-robin tests at four different facilities to assess the reproducibility of the proposed testing methodology. A 10-kW R32 ceiling-type system is tested, and promising coherence of the results is found with coefficient of performance (COP) deviation within 3 % for all the examined conditions, including consistent cycling intervals and compressor speed modulation behaviors.

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

Developing new electrode materials or electrolytes for lithium-ion batteries requires reliable electrochemical testing thereof. In academic research, coin-type cells and small pouch-type cells are commonly being assembled for this purpose. In our study [1], using commercial highly homogeneous and robust LiNi0.33Mn0.33Co0.33O2 (NMC111) cathodes, graphite anodes and 1M LiPF6 in EC/DMC with 3% VC as the electrolyte, four experienced researchers from the Institute for Applied Materials at Karlsruhe Institute of Technology assembled a variety of coin cells within a round robin test. For different cell building parameters, the battery lifetimes systematically varied from a few hundred to well over 2000 cycles before a capacity retention of 80 % was reached. As a benchmark, the same electrodes and electrolyte were incorporated as single- and multi-layer electrode stacks into pouch-type cells and reach almost 4000 cycles with a rate of 1 C.Missplacing of electrodes and varying amount of electrolyte within a coin-cell were already addressed as performance influencing factors in the literature. In this study, one clear outcome with high impact on previously collected electrochemical data on coin cells, is that the steel grade of cell parts, as well as the in-housed total height of the electrode stack have dramatic influence on cell lifetime and the quality of the acquired electrochemical data. We present our best practice for coin cell manufacturing resulting from the round robin test. Further, it is shown that inappropriate testing conditions like poor cell contacting and cycler settings have additional impact on data collection. In this regard, we emphasize essential parameters for obtaining high quality data.Additionally, using the same electrodes, we show direct rate performance differences of calendered vs. uncalendered electrodes, as well as half vs. full-cell test results by means of rate capability and long-term cycling stability. While compression of anodes is less crucial for rate capability, substantial differences are measured in case of the cathodes, highlighting the importance of sufficient cathode densification. Moreover, for long-term capacity retention studies, it is demonstrated that electrode densification of both, cathode and anode is crucial for high long-term capacity retention.Our results are bridging the gap between lab research and industry-type battery cells. It is shown how key performance parameters can be projected from corresponding lab scale battery cell data, if certain important criteria are met vs. where the projections have their limits.[1] A. Smith, P. Stüble, L. Leuthner, A. Hofmann, F. Jeschull and L. Mereacre, Batteries & Supercaps 2023, e202300080. Figure 1

Representativity of ISO test track surface based on controlled pass-by measurements

Within the Polish-Norwegian research project ELANORE, a limited Round Robin Test has been performed on four ISO tracks in Northern Europe. The basic objective of the project is to improve the EU directive on labelling of tyres for noise and rolling resistance. This directive is based on the measurement procedures proscribed in the UNECE Reg.117. Measurements on 3 ISO tracks were performed in 2021 and presented at InterNoise 2022. This paper adds results from tests conducted on a fourth ISO track as well as on trafficked roads with different conventional pavements: 2 in Norway (MA11 and SMA16) and 3 in Poland (SMA8, SMA11 and EACC). On all ISO test tracks and road test sites the same car, test tyres and test equipment as well as the same personnel were used to minimize the measurement uncertainties. Measurements were done using the controlled pass-by (CPB) method for vehicle test speeds between 40 and 90 km/h, with 2 test conditions: according to Reg.117 and with so-called "light test conditions". The main conclusion is that the noise ranking of the tyres on both, the ISO tracks and conventional pavements do not correspond to the ranking based on the label values given by tyre manufacturers.

Diffusion equation-based modelling of reverberation chambers for sound absorption measurements

Recent research in reverberation chambers has revealed unacceptably large variations resulting from round-robin tests of the standardized measurements of random-incidence absorption coefficients. These variations have prompted active research activities in architectural acoustics. This study applies a diffusion equation model (DEM) in acoustics of reverberation chambers for random incidence absorption measurements by predicting both reverberant sound energies and energy flows. The DEM is of high computational efficiency when compared with other existing geometrical acoustics and wave-based methods. The DEM modeling of the sound energy flows in a reverberation room further reveals violations of the diffuse field assumption near the boundary area of absorbing sample under test. Due to its computational efficiency and higher order of the reverberant energy prediction of the statistical room-acoustic modeling, this work investigates an estimation approach to the absorption coefficients of the sample under test. The proposed approach estimates the absorption coefficients by pursuing both the DEM simulations and the chamber-based measurements. This paper investigates sound energy flux over varied absorbing degrees of absorber samples in standardized sizes, computational efficiency of the DEM for reverberant energy decays in reverberation chambers, and potential significance applied to random-incident absorption coefficient measurements.

Performance and Interlaboratory Reproducibility of Droplet Digital Polymerase Chain Reaction (ddPCR) and Real Time PCR for KIT D816V Mutation Detection: A Nationwide Pilot Study By the RIMA (Rete Italiana Mastocitosi) Association

Systemic Mastocytosis (SM) is a rare hematological neoplasm, but its incidence is probably underestimated because of the heterogeneity of clinical symptoms and presentation that may cause diagnostic difficulties especially outside reference centers. Detection of the activating D816V KIT mutation in the bone marrow or peripheral blood is one of the minor criteria for the diagnosis of SM, but it poses some challenges since in the indolent forms (the most frequent) the mast cell burden is very low. For this reason, the National Comprehensive Cancer Network and the European Competence Network on Mastocytosis (ECNM) recommend a high-sensitivity PCR-based assay, such as Allele-Specific Oligonucleotide-Real Time Quantitative PCR (ASO-qPCR) or ddPCR, while Sanger and Next Generation Sequencing are considered not adequate. Accurate quantitation of allele burden (AB) is also desirable since it offers diagnostic (an AB³10% qualifies as a B-finding according to the latest WHO classification) and prognostic information and might be used to monitor response to tyrosine kinase inhibitors. Despite the widespread routine availability of real time and digital PCR technologies, a map of labs across Italy offering KIT D816V testing with adequate sensitivity is lacking, nor have cooperative efforts aimed to check lab performance and reproducibility of diagnostic results ever been performed. Based on these premises, RIMA undertook, with the sponsorship of the GIMEMA Working Party on Chronic Myeloproliferative Neoplasms, a project aimed to: i) build a nationwide network of competent reference laboratories performing KIT D816V mutation testing; ii) promote harmonization of local procedures and ensure adequate proficiency and cross-comparability of results. The pilot phase of this project involved 7 labs (L) spread across the country (Milan, Bologna, Verona, Florence, Rome, Naples, Pavia) serving one or more reference clinical centers for the diagnosis and management of SM. First, a survey aimed to assess the techniques and procedures in use in each participating lab was conducted. Five labs (L2-L6) used a commercial ddPCR assay (KIT p.D816V c.2447A&amp;gt;T, Assay ID dHsaCP2000023; Bio-Rad); one lab (L7) used a home brew ASO-qPCR assay; one lab (L1) used a commercial semi-quantitative real time PCR-based assay (PlentiPlex Mastocytosis D816V kit; Pentabase). All labs performed analyses in duplicate or triplicate using DNA as input material, with amounts variable from 50 to 250ng/replicate. Reported limit of detection (LoD) was 0.0003% for the home brew method and 0.01% for the commercial methods. Subsequently, a round robin test to evaluate and compare performance in terms of sensitivity and inter-lab reproducibility was carried out. Mutated and wild-type DNA isolated from HMC-1.2 and HL-60 cells, respectively, was mixed and diluted to mimic different D816V ABs, from 10% down to 0.01%. Dilutions were externally assessed by the UK Wessex Genomics Laboratory Service, using an accredited ddPCR assay with a limit of detection (LoD) of 0.01%. Of note, the sixth dilution (D6) was scored as slightly below their LoD (0.008%; 3 positive droplets only). Identical batches of blinded vials were then distributed and analyzed in parallel by the 7 participating labs according to their own routine protocols. Positivity/negativity as scored by L1-7 and AB values as scored by L2-7 are detailed in Table 1. All the evaluated methods proved highly accurate in the detection and, for ddPCR and ASO-qPCR, in the quantitation of the KIT D816V (R 2 between 0.988 and 0.998). A very high degree of concordance was achieved, for all dilutions, across different labs and methods (CV between 0.07 and 0.8). D6 was scored borderline by L1 and positive by all other labs. This pilot experience demonstrates that the evaluated PCR-based methods may reliably identify and quantitate the KIT D816V mutation down to an AB of 0.01% with a high degree of cross-comparability of results, thus assisting clinicians in the diagnosis and monitoring of SM patients. To the best of our knowledge, this is the first cooperative effort aimed to assess the performance and reproducibility of KIT D816V mutation testing in SM. Involvement of additional Italian labs is already planned, and further implementation within the ECNM will be proposed. Definition of common SOPs, uniform sample requirements and web-based reporting following the GIMEMA LabNet model will be pursued.

Screening strategy for developing thermoelectric interface materials.

Thermoelectric interface materials (TEiMs) are essential to the development of thermoelectric generators. Common TEiMs use pure metals or binary alloys but have performance stability issues. Conventional selection of TEiMs generally relies on trial-and-error experimentation. We developed a TEiM screening strategy that is based on phase diagram predictions by density functional theory calculations. By combining the phase diagram with electrical resistivity and melting points of potential reaction products, we discovered that the semimetal MgCuSb is a reliable TEiM for high-performance MgAgSb. The MgCuSb/MgAgSb junction exhibits low interfacial contact resistivity (ρc <1 microhm square centimeter) even after annealing at 553 kelvin for 16 days. The fabricated two-pair MgAgSb/Mg3.2Bi1.5Sb0.5 module demonstrated a high conversion efficiency of 9.25% under a 300 kelvin temperature gradient. We performed an international round-robin testing of module performance to confirm the measurement reliability. The strategy can be applied to other thermoelectric materials, filling a vital gap in the development of thermoelectric modules.

An investigation of bond behavior between composite materials (CFRP, GWMM, KPGC) and substrates (Brick and Concrete) for strengthening existing masonry structures

The use of novel composite materials to repair and upgrade existing masonry structures is a major research topic. The Rilem Technical Committee 250-CSM (Composites for the Sustainable Strengthening of Masonry) and Assocompositi (Italian Industry Association for Composite Materials) conducted a round robin test to study the properties of up to 25 types of composite materials in terms of direct tension and bonding behavior. These research results provide a more comprehensive understanding of the mechanical properties of fabric reinforced cementitious matrix (FRCM) reinforcement systems and further improve the standardization of testing procedures. However, owing to the diversity of composite materials and substrates, these results cannot be directly applied to strengthening existing masonry structures in China.In this study, we aimed to comprehensively investigate the bonding behavior between various commonly used composite materials and substrates. Three brick types commonly used in rural areas of China were selected as substrates, namely clay solid brick, shale perforated brick, and concrete hollow block, and three mainstream composite materials were selected as reinforcement materials, namely carbon fiber-reinforced polymer (CFRP), galvanized wire mesh mortar matrix (GWMM), and knitted polyester geogrid cementitious matrix (KPGC). It should be noted that both GWMM and KPGC can be viewed as FRCMs, because they comprise both a fabric and matrix. First, the mechanical properties of the composites were determined by unidirectional tensile tests. Second, single- and double-lap tests were conducted using a specially designed test setup. A comprehensive analysis of the experimental results was conducted, including failure modes, load-global slip curves, failure loads, peak stresses, and exploitation ratios. Finally, the prediction formula for the bonding load capacity of the composite materials mentioned above was explored using the experimental results recorded in this study and relevant literature. The results not only explain the bonding behavior among CFRP, GWMM, PGCM and different substrates, but also broaden the material selection scopes in the repair process of existing masonry structures in a large number of villages and towns in China.

Reliability Analysis of PAUT Based on the Round-Robin Test for Pipe Welds with Thermal Fatigue Cracks.

Thermal fatigue cracks occurring in pipes in nuclear power plants pose a high degree of risk. Thermal fatigue cracks are generated when the thermal fatigue load caused by local temperature gradients is repeatedly applied. The flaws are mainly found in welds, owing to the effects of stress concentration caused by the material properties and geometric shapes of welds. Thermal fatigue pipes are classified as targets of risk-informed in-service inspection, for which ultrasonic testing, a volumetric non-destructive testing method, is applied. With the advancement of ultrasonic testing techniques, various studies have been conducted recently to apply the phased array ultrasonic testing (PAUT) method to the inspection of thermal fatigue cracks occurring on pipes. A quantitative reliability analysis of the PAUT method must be performed to apply the PAUT method to on-site thermal fatigue crack inspection. In this study, to evaluate the quantitative reliability of the PAUT method for thermal fatigue cracks, we fabricated crack specimens with the thermal fatigue mechanism applied to the pipe welds. We performed a round-robin test to collect PAUT data and determine the validity of the detection performance (probability of detection; POD) and the error in the sizing accuracy (root-mean-square error; RMSE) evaluation. The analysis results of the POD and sizing performance of the length and depth of thermal fatigue cracks were comparatively evaluated with the acceptance criteria of the American Society of Mechanical Engineers Code to confirm the effectiveness of applying the PAUT method.

On the reproducibility of extrusion-based bioprinting: round robin study on standardization in the field

The outcome of three-dimensional (3D) bioprinting heavily depends, amongst others, on the interaction between the developed bioink, the printing process, and the printing equipment. However, if this interplay is ensured, bioprinting promises unmatched possibilities in the health care area. To pave the way for comparing newly developed biomaterials, clinical studies, and medical applications (i.e. printed organs, patient-specific tissues), there is a great need for standardization of manufacturing methods in order to enable technology transfers. Despite the importance of such standardization, there is currently a tremendous lack of empirical data that examines the reproducibility and robustness of production in more than one location at a time. In this work, we present data derived from a round robin test for extrusion-based 3D printing performance comprising 12 different academic laboratories throughout Germany and analyze the respective prints using automated image analysis (IA) in three independent academic groups. The fabrication of objects from polymer solutions was standardized as much as currently possible to allow studying the comparability of results from different laboratories. This study has led to the conclusion that current standardization conditions still leave room for the intervention of operators due to missing automation of the equipment. This affects significantly the reproducibility and comparability of bioprinting experiments in multiple laboratories. Nevertheless, automated IA proved to be a suitable methodology for quality assurance as three independently developed workflows achieved similar results. Moreover, the extracted data describing geometric features showed how the function of printers affects the quality of the printed object. A significant step toward standardization of the process was made as an infrastructure for distribution of material and methods, as well as for data transfer and storage was successfully established.

Multi-performance experimental assessment of autogenous and crystalline admixture-stimulated self-healing in UHPFRCCs: Validation and reliability analysis through an inter-laboratory study

The huge benefits brought by the use of Ultra High-Performance Fibre-Reinforced Cementitious Composites (UHPFRCCs) include their high “intrinsic” durability, which is guaranteed by (1) the compact microstructure and (2) the positive interaction between stable multiple-cracking response and autogenous self-healing capability. Hence, self-healing capability must be properly characterized addressing different performances, thus providing all the tools for completely exploiting such large potential. Within this context, the need is clear for a well-established protocol for self-healing characterization. To this end, in the framework of the Cost Action CA15202 SARCOS, six Round Robin Tests involving 30 partners all around Europe were launched addressing different materials, spanning from ordinary concrete to UHPFRCC, and employing different self-healing technologies. In this paper, the tailored experimental methodology is presented and discussed for the specific case of autogenous and crystalline-admixture stimulated healing of UHPFRCC, starting from the comparison of the results from seven different laboratories. The methodology is based on chloride penetration and water permeability tests in cracked disks together with flexural tests on small beams. The latter ones are specifically aimed at assessing the flexural performance recovery of UHPFRCCs, which stands as their signature design “parameter” according to the most recent internationally recognized design approaches. This multi-fold test approach allows to address both inherent durability properties, such as through-crack chloride penetration and apparent water permeability, and more structural/mechanical aspects, such as flexural strength and stiffness.

Round-robin tests of the different types of sensors for floor impact sounds and vibrations

Recently, floor impact noise monitoring system was introduced for residents to control making noises spontaneously using sound and vibration sensors. The present study aims to investigate the performance and characteristics of various current using sound and vibration sensors which can be eventually compatible with the floor impact noise monitoring system. For measurements of sound sensors, 7 sound microphones were used including 2 condenser types, 4 dynamic types, and 1 electro condenser type. Also, 6 vibration meters were used including 2 MEMS types, 2 Piezo types, and 2 spring types. Sound levels were measured in a semi-anechoic chamber using white noise in the frequency range from 63 Hz to 12.5 kHz. Vibrations were measured using high density wooden panel with an impact ball in the frequency range from 16 Hz to 4 KHz. Round-robin tests were done to confirm the exact performances of all the sensors under same condition. As a result, it was found that dynamic type microphones show the most similar response characterization in comparison with the reference condenser microphone especially in the air-borne sound frequency range from 250 Hz to 2 KHz. Also, it was found that spring type vibration meters show the most appropriate characterization at 63 Hz, most critical structure-borne sound frequency. Thus, the results drawn from the round-robin tests could be used for floor impact noise monitoring systems with the benefit of both economy and performance.

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.

Advances in benchmarking and round robin testing for PEM water electrolysis: Reference protocol and hardware

While the number of publications in the PEM water electrolysis community increases each year, no common ground concerning reference hardware (test cells and test bench) and testing protocols has been yet established. This would, however, be necessary for the comparability of experimental results. First attempts for such reference hardware and procedures have been made in the framework of the Task 30 Electrolysis within the Technology Collaboration Programme on Advanced Fuel Cells (AFC TCP) of the International Energy Agency (IEA). Since then, improvements of both the test hardware (test cell and components) as well as the measurement protocol were identified, and a revised methodology and key results based on a comprehensive measurement series have been obtained. A detailed protocol for testing commercial reference components with a reference laboratory test cell developed in-house by Fraunhofer ISE is presented. For evaluation of the protocol and the hardware, it was tested at three different institutions at the same time. Impedance spectroscopic and polarization data was acquired and analyzed. The obtained differences in performance were calculated to give the community an expectation window to compare own data to. Finally, the importance of a thorough temperature control and the conditioning phase are demonstrated.

CFD analysis of hydrodynamic force on a horizontal axis tidal turbine

Horizontal axis tidal turbines are similar to wind turbines in both geometry and principle of operation, yet they need to withstand much heavier loadings and extreme conditions in a harsh operating environment. Consequently, the loadings on tidal turbine blades need to be accurately evaluated within the design stage to ensure they can withstand loadings with little need for repair. With the advancement of computational capabilities, computational fluid dynamics offers a relatively inexpensive method of simulating working conditions and estimating loadings, compared to traditional physical testing, while maintaining accuracy and applicability under a range of operating conditions. In this research, a computational fluid dynamics model of a tidal turbine rotor has been developed using commercial code ANSYS CFX, where the three-dimensional blade geometry is developed from the prototype tidal turbine used in the Round Robin Tests in the framework of the H2020 MaRINET2 Infrastructures Network project. The outputs from the numerical model are validated against the experimental results, where it is revealed that with an increasing rotating speed of the tidal turbine, the thrust force that turbine experienced increases, while the torque force experiences a rise firstly, reaching a maximum value and then decreases gradually. In addition, the experimental results show that during the operation of ocean tidal turbines, the turbine blades experience frequent and large-scale fluctuation of hydrodynamic loads, including thrust and torque, which may lead to tidal turbine blade damage due to fatigue. Therefore, the next stage of development with this numerical model is fatigue loading evaluation, in order to improve the present fatigue design and testing of tidal turbine blades, while gaining a greater understanding of the damage mechanisms.