Metrologia最新文献

{"title":"Calibrating laser Doppler anemometers utilizing an optical chopper.","authors":"Christopher J Crowley, Iosif I Shinder, Michael R Moldover, Joey T Boyd, B James Filla, Aaron N Johnson","doi":"10.1088/1681-7575/adac64","DOIUrl":"10.1088/1681-7575/adac64","url":null,"abstract":"<p><p>Laser Doppler anemometers (LDAs) use scattered light to determine velocity components of a flowing fluid. The operating principal of LDAs is simple conceptually; however, it is impractical to trace the LDA-determined velocities to the SI by characterizing the LDA's subsystems that generate, detect, and process optical signals because these subsystems are complex and include proprietary features. To circumvent this, we calibrated the complete LDA systems utilizing an optical chopper blade as an accurate, SI-traceable velocity standard. The calibrations achieved the expanded velocity uncertainty 0.094% at a 95% confidence level. We calibrated two LDAs that differed in manufacturer, focal length (in the ratio 3.3:1), sensing volume (in the ratio 100:1), and orientation (vertical and horizontal bisectors of the LDA's crossing beams). To compare the calibrations, we measured airspeeds in NIST's wind tunnel using both LDAs. The results differed from each other by, at most, 0.2% throughout the airspeed range (0.5-30) m s^-1.</p>","PeriodicalId":18444,"journal":{"name":"Metrologia","volume":"62 2","pages":""},"PeriodicalIF":2.1,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12013214/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144034570","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Conversion of a piston-cylinder dimensional dataset to the effective area of a mechanical pressure generator.","authors":"Patrick F Egan, Eric S Stanfield, John R Stoup, Christopher W Meyer","doi":"10.1088/1681-7575/ad77db","DOIUrl":"10.1088/1681-7575/ad77db","url":null,"abstract":"<p><p>Recent developments in diameter metrology at NIST have improved the dimensional characterization of piston-cylinder assemblies (PCAs) to unprecedented precision. For the newest generation of PCAs, the standard uncertainty in the measurement of the outer diameter is 12 nm, while uncertainty in the measurement of the inner diameter is 14 nm. With a high-accuracy dimensional dataset in hand, the task of determining the pressure generated by a specific PCA is reduced to converting the diameter (and straightness and roundness) to an effective area (and distortion coefficient). The details on how this was performed for the artifact PCA2062 are described. PCA2062 was dimensioned in 2017 and 2020; the area repeated within <math><mrow><mn>0.2</mn> <mo>×</mo> <msup><mn>10</mn> <mrow><mo>-</mo> <mn>6</mn></mrow> </msup> <mo>⋅</mo> <msub><mi>A</mi> <mn>0</mn></msub> </mrow> </math> . The calculation produced estimates of fall rate and rotation decay that agreed with experimental observations within 12 %. The fall rate is proportional to the square of the gap width; therefore, the agreement between calculation and measurement validates the dimensional estimate of the gap width within (36 ± 42) nm, where the 42 nm standard uncertainty is governed by the present state of flow theory. The piston gage model is buttressed by three comparison tests against a laser barometer, which support a view that PCA2062 is linear and reproducible within 0.2 μPa Pa^-1. Finally, an estimate of uncertainty in the effective area of a dimensioned artifact is provided: as expected, the diameter measurement is the main culprit, but there are open questions regarding the flow model that preclude an accurate evaluation of the distortion coefficient. For the 530 kPa operating range of PCA2062, distortion is not a significant problem, but the effect would be dominant in assemblies operating at 1 MPa and above.</p>","PeriodicalId":18444,"journal":{"name":"Metrologia","volume":"61 6","pages":""},"PeriodicalIF":2.1,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11494611/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142503477","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluating the structural and predictive validity of a derivational morphology task with struggling adult readers.","authors":"Gal Kaldes, Elizabeth L Tighe","doi":"10.1007/s11145-023-10462-y","DOIUrl":"10.1007/s11145-023-10462-y","url":null,"abstract":"<p><p>The purpose of this study was to (a) examine the underlying assessment structure of the Derivational Morphology Task (DMORPH) and (b) investigate the relation of the DMORPH to vocabulary and reading comprehension outcomes with a sample of struggling adult readers. Specifically, participants included 218 struggling adult readers enrolled in adult literacy classes. We used item-level analyses to evaluate the underlying structure of the DMORPH. Items with phonological (e.g., \"music\" to \"musician\") and non-phonological transformations (\"teach\" to \"teacher\") were examined in relation to adult literacy students' vocabulary and reading comprehension skills. A bifactor model was the best fit to the data, suggesting that the DMORPH measured a single factor of derivational morphological awareness with some variation due to phonological and non-phonological change items. Follow-up analyses revealed that the DMORPH can essentially be considered unidimensional, which justified the use of a single scoring system for the DMORPH with adult literacy students. However, after controlling for word reading and phonological awareness, the phonological change items uniquely predicted vocabulary knowledge and reading comprehension, whereas the non-phonological change items were not significant. The results support the structural validity of the DMORPH and the need to use both phonological and non-phonological change items with adult literacy students. The present findings also provide insight into potential intervention targets for instructors in adult literacy programs who are interested in improving students' vocabulary and reading comprehension skills.</p>","PeriodicalId":18444,"journal":{"name":"Metrologia","volume":"55 1","pages":"2101-2126"},"PeriodicalIF":2.0,"publicationDate":"2024-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11544760/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82768917","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A robust time scale for space applications using the student’s t-distribution","authors":"Hamish McPhee, Jean-Yves Tourneret, David Valat, Jérôme Delporte, Yoan Grégoire and Philippe Paimblanc","doi":"10.1088/1681-7575/ad7606","DOIUrl":"https://doi.org/10.1088/1681-7575/ad7606","url":null,"abstract":"In this article, the principles of robust estimation are applied to the standard basic time scale equation to obtain a new method of assigning weights to clocks. Specifically, the Student’s t-distribution is introduced as a new statistical model for an ensemble of clocks that are experiencing phase jumps, frequency jumps or anomalies in their measurement links. The proposed robust time scale is designed to mitigate the effects of these anomalies without necessarily identifying them, but through applying a method of robust estimation for the parameters of a Student’s t-distribution. The proposed time scale algorithm using the Student’s t-distribution (ATST) is shown to achieve comparable robustness to phase jumps, frequency jumps, and anomalies in the measurements with respect to the AT1 oracle time scale. The AT1 oracle is a special realization of the AT1 time scale which corrects all anomalies by having prior knowledge of their occurrences. The similar performance of ATST and AT1 oracle suggests that the ATST algorithm is efficient for obtaining robustness with no prior knowledge or detection of the occurrences of anomalies.","PeriodicalId":18444,"journal":{"name":"Metrologia","volume":"31 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142263943","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A digital four-arm bridge for the comparison of resistance with capacitance","authors":"Yicheng Wang and Stephan Schlamminger","doi":"10.1088/1681-7575/ad7590","DOIUrl":"https://doi.org/10.1088/1681-7575/ad7590","url":null,"abstract":"We have built and demonstrated a digital four-arm bridge for the comparison of resistance with capacitance. The digital four-arm bridge mimics the classical quad bridge in the digital domain with three balances: the source balance, the detector balance, as well as the main balance. Due to correlation, the required precision of the source voltages is only of the order of the square root of the ultimate bridge precision. For the comparison of a 100 kΩ resistor with a 1 nF capacitor near 1592 Hz, the combined standard uncertainty is .","PeriodicalId":18444,"journal":{"name":"Metrologia","volume":"25 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224707","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Traceable characterisation of fibre-coupled single-photon detectors","authors":"Luke Arabskyj, Philip R Dolan, Adam L Parke, Ted S Santana, Simon R G Hall, Geiland Porrovecchio, Marek Smid, Marco Lucamarini, Christopher J Chunnilall","doi":"10.1088/1681-7575/ad70bc","DOIUrl":"https://doi.org/10.1088/1681-7575/ad70bc","url":null,"abstract":"The detection of single photons plays an essential role in advancing single-photon science and technologies. Yet, within the visible/near-infrared spectral region, accurate fibre-based optical power measurements at the few-photon level are not yet well-established. In this study, we report on a fibre-based setup, enabling traceable optical power measurements at the few-photon level in this spectral region. The setup was used to calibrate the detection efficiency (DE) of four single-photon avalanche diode (SPAD) detectors. The relative standard uncertainties on the mean DE values obtained from repeat fibre-to-detector couplings ranged from 0.67% to 0.81% (<italic toggle=\"yes\">k</italic> = 2). However, the relative standard deviation of DE values, which ranged from 1.38% to 3.20% (<italic toggle=\"yes\">k</italic> = 2), poses a challenge for the metrology of these devices and applications that require high accuracy and repeatability. We investigated the source of these variations by spatially mapping the response of a detector’s fibre connector port, using a focused free-space beam, allowing us to estimate the detector’s spatial non-uniformity. In addition, we realise a novel calibration approach for fibre-coupled SPADs in a free-space configuration, enabling a direct comparison between the fibre-based setup and the National Physical Laboratory’s established free-space facility using a single SPAD. Finally, we investigated alternative coupling methods, testing the repeatability of different fibre-to-fibre connectors in addition to direct fibre-to-detector couplings: SPADs from three manufacturers were tested, with both single-mode and multi-mode fibre.","PeriodicalId":18444,"journal":{"name":"Metrologia","volume":"32 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190966","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An emf-temperature reference function for Pt–20%Rh versus Pt thermocouples in the temperature range of 0 °C to 1100 °C","authors":"F Edler, P Ederer, K Huang","doi":"10.1088/1681-7575/ad746b","DOIUrl":"https://doi.org/10.1088/1681-7575/ad746b","url":null,"abstract":"An electromotive force–temperature reference function for thermocouples made of platinum–20%rhodium versus platinum (Pt–20%Rh/Pt) was determined for the temperature range from 0 °C to 1100 °C. Three Pt–20%Rh/Pt thermocouples were constructed at the Physikalisch-Technische Bundesanstalt (PTB) and were compared with standard platinum resistance thermometers, an Au/Pt thermocouple and a Pt/Pd thermocouple, which were all calibrated at fixed points of the International Temperature Scale of 1990 (ITS-90). The comparison measurements were performed in stirred liquid baths in the range from 0 °C to 545 °C, in a sodium heat pipe from 560 °C to 980 °C, and in a five-zone furnace at temperatures between 1000 °C and 1100 °C. Furthermore, the Pt–20%Rh/Pt thermocouples were calibrated at fixed points of the ITS-90. The PTB reference function based on two of the three Pt–20%Rh/Pt thermocouples has an expanded measurement uncertainty of 0.25 K in the temperature range from 0 °C to 1100 °C.","PeriodicalId":18444,"journal":{"name":"Metrologia","volume":"42 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-09-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224709","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phase reconstruction by phase shift estimation with reliable parameter minimization","authors":"Yu Zhang, Bao Liu","doi":"10.1088/1681-7575/ad6b2f","DOIUrl":"https://doi.org/10.1088/1681-7575/ad6b2f","url":null,"abstract":"Achieving a balance between accuracy and speed in phase reconstruction is a challenging problem. In phase-shifting interferometry, increasing the speed by reducing the number of phase shifts while maintaining high accuracy is highly desirable. We propose an accurate and efficient two-step phase reconstruction method utilizing random phase shift. This method directly estimates the phase shift through reliable parameter minimization, allowing for easy and precise phase reconstruction. Simulations and experiments demonstrate the superior performance of our method across various scenarios, outperforming well-known two-step phase-shifting algorithms. We expect this paper to provide a general and powerful tool for phase reconstruction.","PeriodicalId":18444,"journal":{"name":"Metrologia","volume":"9 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-09-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190967","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"COOMET key comparison COOMET.PR-K1.a.2018 for spectral irradiance 250 nm to 2500 nmm, final report","authors":"B B Khlevnoy, M V Solodilov, S S Kolesnikova, D A Otryaskin, I V Korseko, S V Nikanenka, M V Huriev, F Sametoğlu","doi":"10.1088/0026-1394/61/1a/02001","DOIUrl":"https://doi.org/10.1088/0026-1394/61/1a/02001","url":null,"abstract":"<title>Main text</title>This report describes the Key Comparison COOMET.R-K1.a.2018 for spectral irradiance in the wavelength range of 250 nm to 2500 nm, conducted by the Regional Metrology Organization \"Euro-Asian Cooperation of National Metrological Institutions\" (COOMET). The comparison was, in fact, a combination of three bilateral comparisons with the same link/pilot laboratory - the All-Russian Research Institute for Optical and Physical Measurements (VNIIOFI), the Russian Federation. The non-link laboratories were the Belarusian State Institute of Metrology (BelGIM), Belarus, the National Scientific Centre \"Institute of Metrology\" (NSC IM), Ukraine, and the National Metrology Institute of Türkiye (TÜBİTAK UME), Türkiye.The aim of the comparison was to link the BelGIM, NSC IM and TÜBİTAK UME measurement results to the CIPM key comparison CCPR-K1.a.2017, conducted by the Consultative Committee for Photometry and Radiometry (CCPR).Tungsten quartz halogen lamps of the FEL type (1000 W) were used as artefacts. Each participant used its own set of lamps. The sequence of measurements was <italic toggle=\"yes\">participant - pilot - participant</italic>. The pilot measurements of the described here COOMET comparison were performed in a short time (within three months) after completing the measurements of CCPR-K1.a.2017, where VNIIOFI also was a pilot, which provided a high quality link.NSC IM performed measurements in the full spectral range, from 250 nm to 2500 nm, while BelGIM and TÜBİTAK UME managed to cover the range from 250 nm to 1100 nm only.The analysis of the comparison was performed following the approach described in the Appendix A of the Guidelines for CCPR and RMO Bilateral Key Comparisons (CCPR-G5). Differences from KCRV of BelGIM and TÜBİTAK UME, for the most of the measured wavelengths, do not exceed 2% and are within the expanded uncertainties. For NSC IM the differences from KCRV are within or comparable with the uncertainties in the IR range, from 900 nm to 2500 nm, but become larger with decreasing wavelength in the visible and UV reaching 9% at 250 nm.To reach the main text of this paper, click on <ext-link xlink:href=\"https://www.bipm.org/documents/d/guest/coomet-pr-k1a-2018\" xlink:type=\"simple\">Final Report</ext-link>. Note that this text is that which appears in Appendix B of the BIPM key comparison database <ext-link xlink:href=\"https://www.bipm.org/kcdb/\" xlink:type=\"simple\">https://www.bipm.org/kcdb/</ext-link>.The final report has been peer-reviewed and approved for publication by the CCPR, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).","PeriodicalId":18444,"journal":{"name":"Metrologia","volume":"18 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142224708","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Final report, ongoing key comparison BIPM.QM-K1, ozone at ambient level, comparison with CMS/ITRI, March 2024","authors":"Joële Viallon, Faraz Idrees, Philippe Moussay, Robert Wielgosz, Jim Norris, Peter Trask, Shih-Fang Chen, Yun Feng","doi":"10.1088/0026-1394/61/1a/08013","DOIUrl":"https://doi.org/10.1088/0026-1394/61/1a/08013","url":null,"abstract":"<title>Main text</title>As part of the ongoing key comparison BIPM.QM-K1, a comparison has been performed between the ozone standard of Chinese Taipei maintained by the Industrial Technology Research Institute/Center for Measurement Standards (CMS/ITRI) and the common reference standard of the key comparison, maintained by the Bureau International des Poids et Mesures (BIPM). The instruments have been compared over a nominal ozone amount fraction range of 0 nmol mol−1 to 500 nmol mol−1.To reach the main text of this paper, click on <ext-link xlink:href=\"https://www.bipm.org/documents/d/guest/bipm-qm-k1_cms_2024\" xlink:type=\"simple\">Final Report</ext-link>. Note that this text is that which appears in Appendix B of the BIPM key comparison database <ext-link xlink:href=\"https://www.bipm.org/kcdb/\" xlink:type=\"simple\">https://www.bipm.org/kcdb/</ext-link>.The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).","PeriodicalId":18444,"journal":{"name":"Metrologia","volume":"38 1","pages":""},"PeriodicalIF":2.4,"publicationDate":"2024-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142190688","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}