Pub Date : 2013-07-15DOI: 10.51843/wsproceedings.2013.34
M. Lombardi
GPS disciplined oscillators (GPSDOs) are commonly used as references for frequency calibrations. Over long intervals, a GPSDO is an inherently accurate source of frequency because it is continuously adjusted to agree with the Coordinated Universal Time (UTC) time scale maintained by the United States Naval Observatory (USNO). However, most frequency calibrations last for intervals of one day or less, and it can be difficult for metrologists to determine the uncertainty of a GPSDO during a short interval, and even more difficult to prove their uncertainty claims to skeptical laboratory assessors. This paper can serve as a guide to metrologists and laboratory assessors who work with GPSDOs as frequency standards. It describes the relationship between GPS time and Coordinated Universal Time (UTC) and explains why GPS time is traceable to the SI. It discusses how a GPSDO utilizes the GPS signals to control the frequency of its local oscillator. It explains how to estimate frequency stability, and how to apply estimates of frequency stability to determine the uncertainty of a GPSDO used as the reference for a frequency calibration.
{"title":"Determining the Uncertainty of Frequency Measurements Referenced to GPS Disciplined Oscillators","authors":"M. Lombardi","doi":"10.51843/wsproceedings.2013.34","DOIUrl":"https://doi.org/10.51843/wsproceedings.2013.34","url":null,"abstract":"GPS disciplined oscillators (GPSDOs) are commonly used as references for frequency calibrations. Over long intervals, a GPSDO is an inherently accurate source of frequency because it is continuously adjusted to agree with the Coordinated Universal Time (UTC) time scale maintained by the United States Naval Observatory (USNO). However, most frequency calibrations last for intervals of one day or less, and it can be difficult for metrologists to determine the uncertainty of a GPSDO during a short interval, and even more difficult to prove their uncertainty claims to skeptical laboratory assessors. This paper can serve as a guide to metrologists and laboratory assessors who work with GPSDOs as frequency standards. It describes the relationship between GPS time and Coordinated Universal Time (UTC) and explains why GPS time is traceable to the SI. It discusses how a GPSDO utilizes the GPS signals to control the frequency of its local oscillator. It explains how to estimate frequency stability, and how to apply estimates of frequency stability to determine the uncertainty of a GPSDO used as the reference for a frequency calibration.","PeriodicalId":445779,"journal":{"name":"NCSL International Workshop & Symposium Conference Proceedings 2013","volume":"265 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"120892889","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2013-05-08DOI: 10.51843/wsproceedings.2013.38
S. S. Bruce
A Look at its Past Decade and a Gaze towards its Future. As the National Metrology Institute (NMI) for the United States, the National Institute of Standards and Technology (NIST), formerly the National Bureau of Standards, has provided measurement services, both calibrations and reference materials, for more than 100 years. Through these services, our customers have benefitted from our measurement capabilities and expertise in many areas, including amount of substance; dimensional metrology; electricity and magnetism; ionizing radiation; mass and related quantities; photometry and radiometry; thermodynamics; and time and frequency. NIST’s customers have also had access to some of the lowest measurement uncertainties available and a dependable way to establish traceability to the International System of Units (SI) [http://www.nist.gov/pml/wmd/metric/si-units.cfm].In response to the signing of the International Committee for Weights and Measures (CIPM) Mutual Recognition Arrangement (MRA), NIST first established an institution-wide quality system for the measurement services 10 years ago [http://www.bipm.org/en/cipm-mra/objectives.html]. NIST’s Quality System for Measurement Services has advanced the quality of service and measurements we provide our customers by fostering an environment in which NIST management and staff work towards continual improvement in the development and delivery of NIST measurement services. This paper describes NIST’s Quality System for the Measurement Services and its relevance to international standards of quality, such as the International Organization for Standardization and the International Electrotechnical Commission (ISO/IEC) 17025 standard and ISO Guide 34 [http://www.nist.gov/nistqs/]. It also provides a history of this quality system and a glimpse of future goals for improving its implementation.
{"title":"The NIST Quality System for Measurement Services: A look at its Past Decade and a Gaze towards its Future","authors":"S. S. Bruce","doi":"10.51843/wsproceedings.2013.38","DOIUrl":"https://doi.org/10.51843/wsproceedings.2013.38","url":null,"abstract":"A Look at its Past Decade and a Gaze towards its Future. As the National Metrology Institute (NMI) for the United States, the National Institute of Standards and Technology (NIST), formerly the National Bureau of Standards, has provided measurement services, both calibrations and reference materials, for more than 100 years. Through these services, our customers have benefitted from our measurement capabilities and expertise in many areas, including amount of substance; dimensional metrology; electricity and magnetism; ionizing radiation; mass and related quantities; photometry and radiometry; thermodynamics; and time and frequency. NIST’s customers have also had access to some of the lowest measurement uncertainties available and a dependable way to establish traceability to the International System of Units (SI) [http://www.nist.gov/pml/wmd/metric/si-units.cfm].In response to the signing of the International Committee for Weights and Measures (CIPM) Mutual Recognition Arrangement (MRA), NIST first established an institution-wide quality system for the measurement services 10 years ago [http://www.bipm.org/en/cipm-mra/objectives.html]. NIST’s Quality System for Measurement Services has advanced the quality of service and measurements we provide our customers by fostering an environment in which NIST management and staff work towards continual improvement in the development and delivery of NIST measurement services. This paper describes NIST’s Quality System for the Measurement Services and its relevance to international standards of quality, such as the International Organization for Standardization and the International Electrotechnical Commission (ISO/IEC) 17025 standard and ISO Guide 34 [http://www.nist.gov/nistqs/]. It also provides a history of this quality system and a glimpse of future goals for improving its implementation.","PeriodicalId":445779,"journal":{"name":"NCSL International Workshop & Symposium Conference Proceedings 2013","volume":"122 3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2013-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131288687","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.51843/wsproceedings.2013.27
Logan Kunitz
There is no shortage of literature on how to use Agile and Scrum to speed up software development and deploy working code more frequently, however many of the concepts presented these days are geared toward pure software solutions, that are often web-based, where testing can be fully automated. This paper will address using Scrum and Agile software development practices in solutions that have hardware and/or regulatory dependencies, and a distributed development team. The hardware and regulatory dependencies, and distributed development team, can complicate the use of these development practices and limit the frequency of deploying working code due to the time consuming testing that is often involved • sometimes delaying a release for months. This is very different than with some pure software solutions, developed locally, that strive to be able to deploy working software “continuously” through the use of automated testing. This paper will attempt to reconcile the issues around using Agile and Scrum for developing HW and regulatory dependent software solutions that are not fully addressed in many agile / scrum literature and presentations. We’ll start by revisiting the core principles around agile / scrum development, and testing best practices. Then, we’ll look at examples from our own development processes at National Instruments, where we’ve adopted an agile process for the development of our software application that is used to automate the calibration of NI’s many hardware products, for both our internal service laboratory and 3rd party metrology laboratories. This application presents a number of challenges that should resonate for any software group that has a large number of hardware dependencies or regulatory requirements on their applications. For example, the broad portfolio of NI products and instrument standards that this application supports, makes regression testing for large changes an extremely time consuming task. Finally, we will address some of the challenges with using scrum with a global team, as we have developers split between Austin, TX and Hungary.
{"title":"Introduction to Agile and Testing Best Practices for Distributed Software Teams with Hardware Dependencies","authors":"Logan Kunitz","doi":"10.51843/wsproceedings.2013.27","DOIUrl":"https://doi.org/10.51843/wsproceedings.2013.27","url":null,"abstract":"There is no shortage of literature on how to use Agile and Scrum to speed up software development and deploy working code more frequently, however many of the concepts presented these days are geared toward pure software solutions, that are often web-based, where testing can be fully automated. This paper will address using Scrum and Agile software development practices in solutions that have hardware and/or regulatory dependencies, and a distributed development team. The hardware and regulatory dependencies, and distributed development team, can complicate the use of these development practices and limit the frequency of deploying working code due to the time consuming testing that is often involved • sometimes delaying a release for months. This is very different than with some pure software solutions, developed locally, that strive to be able to deploy working software “continuously” through the use of automated testing. This paper will attempt to reconcile the issues around using Agile and Scrum for developing HW and regulatory dependent software solutions that are not fully addressed in many agile / scrum literature and presentations. We’ll start by revisiting the core principles around agile / scrum development, and testing best practices. Then, we’ll look at examples from our own development processes at National Instruments, where we’ve adopted an agile process for the development of our software application that is used to automate the calibration of NI’s many hardware products, for both our internal service laboratory and 3rd party metrology laboratories. This application presents a number of challenges that should resonate for any software group that has a large number of hardware dependencies or regulatory requirements on their applications. For example, the broad portfolio of NI products and instrument standards that this application supports, makes regression testing for large changes an extremely time consuming task. Finally, we will address some of the challenges with using scrum with a global team, as we have developers split between Austin, TX and Hungary.","PeriodicalId":445779,"journal":{"name":"NCSL International Workshop & Symposium Conference Proceedings 2013","volume":"38 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125517548","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.51843/wsproceedings.2013.51
M. Schiefer, Eric J. Seller, P. Timmons
Low Frequency accelerometer calibration is generally time consuming and requires special considerations and excitation techniques. A new class of reference standard and excitation shaker for use in low frequency accelerometer calibration is introduced. This exciter and reference standard addresses these low frequency challenges and reduces uncertainty to near 1% and throughput by a factor of 3. This paper also outlines challenges of low frequency calibration and details principal sources of error. New developments in low frequency accelerometer calibration excitation technology are introduced. Comparison to manufacturer’s primary calibration of an artifact as well as comparison to primary means is presented.
{"title":"Low Frequency Accelerometer Calibration Chalenges and Improvements","authors":"M. Schiefer, Eric J. Seller, P. Timmons","doi":"10.51843/wsproceedings.2013.51","DOIUrl":"https://doi.org/10.51843/wsproceedings.2013.51","url":null,"abstract":"Low Frequency accelerometer calibration is generally time consuming and requires special considerations and excitation techniques. A new class of reference standard and excitation shaker for use in low frequency accelerometer calibration is introduced. This exciter and reference standard addresses these low frequency challenges and reduces uncertainty to near 1% and throughput by a factor of 3. This paper also outlines challenges of low frequency calibration and details principal sources of error. New developments in low frequency accelerometer calibration excitation technology are introduced. Comparison to manufacturer’s primary calibration of an artifact as well as comparison to primary means is presented.","PeriodicalId":445779,"journal":{"name":"NCSL International Workshop & Symposium Conference Proceedings 2013","volume":"22 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114139691","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.51843/wsproceedings.2013.29
M. Bailey
The design of an AC voltage reference source using a digital to analogue converter controlled by microcontroller to produce a calculable RMS AC voltage reference with accuracy suitable for calibrating high performance Digital multimeters.
{"title":"Digitally Gernerated AC Reference Source","authors":"M. Bailey","doi":"10.51843/wsproceedings.2013.29","DOIUrl":"https://doi.org/10.51843/wsproceedings.2013.29","url":null,"abstract":"The design of an AC voltage reference source using a digital to analogue converter controlled by microcontroller to produce a calculable RMS AC voltage reference with accuracy suitable for calibrating high performance Digital multimeters.","PeriodicalId":445779,"journal":{"name":"NCSL International Workshop & Symposium Conference Proceedings 2013","volume":"98 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125569268","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.51843/wsproceedings.2013.50
G. Rodrigues
With unit sales in excess of one million pieces per year, pipettes are ubiquitous devices and found in a wide variety of laboratories. Applications vary from non-quantitative uses (such as mixing or decanting) to highly quantitative uses such as dispensing of standards and preparation of accurate serial dilutions. Because pipettes are used extensively in critical laboratory tests such as quality control assay of injectable drugs and DNA analysis which results in conviction or exoneration, proper calibration of pipettes is important and the consequences of poor calibrations can be severe. There is a definite upward trend in the number of pipette calibration laboratories and service organizations which have obtained accreditation to ISO/IEC 17025:2005. Each of these laboratories will have performed an uncertainty analysis and calculated their calibration measurement capability (CMC).In this paper, the available scopes of accreditation from forty different pipette calibration laboratories are compiled, compared and contrasted. The various formats were translated into a common basis and then plotted to show how CMCs vary with pipette volume and vary between laboratories. One of the most notable differences is the significant variation in the CMCs among laboratories, which can vary by factors of 100 or more. There appears to be little correlation between a published pipette CMC and other laboratory variables such as experience in the discipline, equipment, reference standards, environmental controls, and capabilities in related disciplines such as mass or volumetrics. To understand the reasons behind these differences in CMC, pipette uncertainty budgets from some leading laboratories were compared. Based on this evaluation, the authors conclude that laboratory practices for establishing pipette calibration CMCs are not well standardized, and the largest source of variation seems to be practice in how the repeatability contribution from the pipette unit under test (UUT) is evaluated and considered. ILAC policy P-14 [1] defines CMC and establishes general policy regarding inclusion of repeatability and reproducibility of the “best existing device”. In practice, there is currently no consensus on which sources of variation in the pipette calibration process should be included in the CMC evaluation, nor is there agreement on how to apply the concept of a best existing pipette. This paper attempts to begin filling this gap by providing recommendations for a best practice in evaluating and communicating the uncertainty of a pipette calibration and for evaluating the CMC of a pipette calibration laboratory. The important questions of reporting measurement uncertainty and the impact it has on evaluating inter-laboratory comparisons and determining compliance with tolerances are also discussed.
{"title":"Best Practices for Pipette Calibration Uncertainty Budgets and CMC Determination","authors":"G. Rodrigues","doi":"10.51843/wsproceedings.2013.50","DOIUrl":"https://doi.org/10.51843/wsproceedings.2013.50","url":null,"abstract":"With unit sales in excess of one million pieces per year, pipettes are ubiquitous devices and found in a wide variety of laboratories. Applications vary from non-quantitative uses (such as mixing or decanting) to highly quantitative uses such as dispensing of standards and preparation of accurate serial dilutions. Because pipettes are used extensively in critical laboratory tests such as quality control assay of injectable drugs and DNA analysis which results in conviction or exoneration, proper calibration of pipettes is important and the consequences of poor calibrations can be severe. There is a definite upward trend in the number of pipette calibration laboratories and service organizations which have obtained accreditation to ISO/IEC 17025:2005. Each of these laboratories will have performed an uncertainty analysis and calculated their calibration measurement capability (CMC).In this paper, the available scopes of accreditation from forty different pipette calibration laboratories are compiled, compared and contrasted. The various formats were translated into a common basis and then plotted to show how CMCs vary with pipette volume and vary between laboratories. One of the most notable differences is the significant variation in the CMCs among laboratories, which can vary by factors of 100 or more. There appears to be little correlation between a published pipette CMC and other laboratory variables such as experience in the discipline, equipment, reference standards, environmental controls, and capabilities in related disciplines such as mass or volumetrics. To understand the reasons behind these differences in CMC, pipette uncertainty budgets from some leading laboratories were compared. Based on this evaluation, the authors conclude that laboratory practices for establishing pipette calibration CMCs are not well standardized, and the largest source of variation seems to be practice in how the repeatability contribution from the pipette unit under test (UUT) is evaluated and considered. ILAC policy P-14 [1] defines CMC and establishes general policy regarding inclusion of repeatability and reproducibility of the “best existing device”. In practice, there is currently no consensus on which sources of variation in the pipette calibration process should be included in the CMC evaluation, nor is there agreement on how to apply the concept of a best existing pipette. This paper attempts to begin filling this gap by providing recommendations for a best practice in evaluating and communicating the uncertainty of a pipette calibration and for evaluating the CMC of a pipette calibration laboratory. The important questions of reporting measurement uncertainty and the impact it has on evaluating inter-laboratory comparisons and determining compliance with tolerances are also discussed.","PeriodicalId":445779,"journal":{"name":"NCSL International Workshop & Symposium Conference Proceedings 2013","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115872611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.51843/wsproceedings.2013.36
Morgana Pizzolato, Filipe Medeiros Albano
This paper presents the analysis of nonconformities found in auditing of testing and calibration laboratories in accordance with ISO/IEC 17025. This International Standard specifies the general requirements for the competence to carry out tests and/or calibrations. It covers testing and calibration performed using standard methods, non-standard methods, and laboratory-developed methods. The auditing was conducted by auditors from Rede Metrológica RS (RMRS). The RMRS is a nonprofit association of technical and scientific nature that acts as an articulator in metrology and quality in Brazil. The main objective of this research was to identify the ISO/IEC 17025 requirements that have a higher number of non-conformities. We collected data on laboratory auditing performed in 2008, 2009, 2010, 2011 and 2012 years that represent about 500 laboratories audits. The data analyses were conducted clustering the laboratories by calibration and test area, by ISO/IEC 17025 requirements and by year. The areas of calibration laboratories were: acoustic; length, electricity, force, torque and hardness, mass, optical, pressure, flow and level, temperature and humidity, time and frequency, viscosity, volume. The areas of testing laboratories were: chemistry and physical chemistry, microbiological, biological and toxicological, mechanical and biochemistry. In the analysis were considered separately the percentages of non-conformities in technical and management requirements and also joint. Among the technical requirements with the highest number of non-conformities are Test and calibration methods and method validation (5.4) and Measurement traceability (5.6). Among the management requirements are Document control (4.3) and Control of records (4.13). Was also possible to identify which area of calibration or test showed a higher number of non-conformities. The calibration areas that had the highest number of non-conformities were pressure, flow and level, temperature and humidity and length. The testing areas that had the highest number of non-conformities were chemistry and physical chemistry and microbiological. Finally, one can see the trend of nonconformities in assessments of laboratories in accordance with the ISO/IEC 17025 requirements using the result of five years.
{"title":"Nonconformities Analysis According to ISO/IEC 17025 in Brazil","authors":"Morgana Pizzolato, Filipe Medeiros Albano","doi":"10.51843/wsproceedings.2013.36","DOIUrl":"https://doi.org/10.51843/wsproceedings.2013.36","url":null,"abstract":"This paper presents the analysis of nonconformities found in auditing of testing and calibration laboratories in accordance with ISO/IEC 17025. This International Standard specifies the general requirements for the competence to carry out tests and/or calibrations. It covers testing and calibration performed using standard methods, non-standard methods, and laboratory-developed methods. The auditing was conducted by auditors from Rede Metrológica RS (RMRS). The RMRS is a nonprofit association of technical and scientific nature that acts as an articulator in metrology and quality in Brazil. The main objective of this research was to identify the ISO/IEC 17025 requirements that have a higher number of non-conformities. We collected data on laboratory auditing performed in 2008, 2009, 2010, 2011 and 2012 years that represent about 500 laboratories audits. The data analyses were conducted clustering the laboratories by calibration and test area, by ISO/IEC 17025 requirements and by year. The areas of calibration laboratories were: acoustic; length, electricity, force, torque and hardness, mass, optical, pressure, flow and level, temperature and humidity, time and frequency, viscosity, volume. The areas of testing laboratories were: chemistry and physical chemistry, microbiological, biological and toxicological, mechanical and biochemistry. In the analysis were considered separately the percentages of non-conformities in technical and management requirements and also joint. Among the technical requirements with the highest number of non-conformities are Test and calibration methods and method validation (5.4) and Measurement traceability (5.6). Among the management requirements are Document control (4.3) and Control of records (4.13). Was also possible to identify which area of calibration or test showed a higher number of non-conformities. The calibration areas that had the highest number of non-conformities were pressure, flow and level, temperature and humidity and length. The testing areas that had the highest number of non-conformities were chemistry and physical chemistry and microbiological. Finally, one can see the trend of nonconformities in assessments of laboratories in accordance with the ISO/IEC 17025 requirements using the result of five years.","PeriodicalId":445779,"journal":{"name":"NCSL International Workshop & Symposium Conference Proceedings 2013","volume":"17 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117108963","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.51843/wsproceedings.2013.24
Dennis W.K. Lee, Francis S.Y. Wong, C. K. Fung
A coordinate measuring machine (CMM) is a measuring system, with the means to move a probe system, to determine spatial coordinates on a work piece surface. It is a 3-dimensional measuring device for determining the physical geometrical characteristics of objects. To verify the performance of a CMM, it is essential to carry out acceptance tests and with subsequent periodic checks to it in accordance with ISO 10360-2, which is an international geometrical product specification standard for CMM testing. At Standards and Calibration Laboratory (SCL), a calibration method, meeting the requirements of the latest edition of ISO 10360-2, is developed using precision step gauges as the reference standards to calibrate CMMs with measurement results traceable to the unit of length (i.e. the metre). Method for estimation of measurement uncertainty is also developed in accordance with the JCGM 100:2008 (Guide to the Expression of Uncertainty in Measurement), ISO/TS 15530-1:2011 and ISO/TS 15530-3:2011 (Guidelines for the Evaluation of CMM Test Uncertainty).Learning Objectives: To develop methods for CMM calibration meeting ISO 10360-2:2009 and uncertainty evaluation in accordance with JCGM 100:2008.
{"title":"Calibration of Coordinate Measuring Machines Meeting the Requirements of ISO 10360-2:2009 at the Standards and Calibration Laboratory","authors":"Dennis W.K. Lee, Francis S.Y. Wong, C. K. Fung","doi":"10.51843/wsproceedings.2013.24","DOIUrl":"https://doi.org/10.51843/wsproceedings.2013.24","url":null,"abstract":"A coordinate measuring machine (CMM) is a measuring system, with the means to move a probe system, to determine spatial coordinates on a work piece surface. It is a 3-dimensional measuring device for determining the physical geometrical characteristics of objects. To verify the performance of a CMM, it is essential to carry out acceptance tests and with subsequent periodic checks to it in accordance with ISO 10360-2, which is an international geometrical product specification standard for CMM testing. At Standards and Calibration Laboratory (SCL), a calibration method, meeting the requirements of the latest edition of ISO 10360-2, is developed using precision step gauges as the reference standards to calibrate CMMs with measurement results traceable to the unit of length (i.e. the metre). Method for estimation of measurement uncertainty is also developed in accordance with the JCGM 100:2008 (Guide to the Expression of Uncertainty in Measurement), ISO/TS 15530-1:2011 and ISO/TS 15530-3:2011 (Guidelines for the Evaluation of CMM Test Uncertainty).Learning Objectives: To develop methods for CMM calibration meeting ISO 10360-2:2009 and uncertainty evaluation in accordance with JCGM 100:2008.","PeriodicalId":445779,"journal":{"name":"NCSL International Workshop & Symposium Conference Proceedings 2013","volume":"88 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116268168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.51843/wsproceedings.2013.17
T. E. Lipe
Determination of ac-dc difference of thermal voltage converters has traditionally been done by range-to-range scaling techniques, beginning at the voltage level and optimal frequency of the primary standards, and continuing until the parameter space has been completed. Range-to-range scaling propagates uncertainties of the measurement process at each step, so that the uncertainties become larger at values away from the primary standards, with the magnitude determined largely from the number of scaling steps. At the National Institute of Standards and Technology (NIST), we have recently fabricated multi junction thermal converters with exceptional properties over a large range of voltages and frequencies. Coupled with the use of an ac voltage standard based on quantum effects, we have reevaluated the NIST uncertainty matrix for ac-dc voltage transfer difference, and have made significant reductions in the uncertainties at all voltage and frequency levels.
{"title":"Reevaluating the NIST Uncertainties for AC-DC Voltage Transfer Difference","authors":"T. E. Lipe","doi":"10.51843/wsproceedings.2013.17","DOIUrl":"https://doi.org/10.51843/wsproceedings.2013.17","url":null,"abstract":"Determination of ac-dc difference of thermal voltage converters has traditionally been done by range-to-range scaling techniques, beginning at the voltage level and optimal frequency of the primary standards, and continuing until the parameter space has been completed. Range-to-range scaling propagates uncertainties of the measurement process at each step, so that the uncertainties become larger at values away from the primary standards, with the magnitude determined largely from the number of scaling steps. At the National Institute of Standards and Technology (NIST), we have recently fabricated multi junction thermal converters with exceptional properties over a large range of voltages and frequencies. Coupled with the use of an ac voltage standard based on quantum effects, we have reevaluated the NIST uncertainty matrix for ac-dc voltage transfer difference, and have made significant reductions in the uncertainties at all voltage and frequency levels.","PeriodicalId":445779,"journal":{"name":"NCSL International Workshop & Symposium Conference Proceedings 2013","volume":"60 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126483059","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 1900-01-01DOI: 10.51843/wsproceedings.2013.01
B. Djokic
Calibration of Rogowski Coils at High Pulsed Currents. The many applications of Rogowski coils include their use as current sensors in AC resistance welding. Weld quality depends on monitoring/controlling the welding currents. The accuracy of these current sensors matters, and so does the accuracy of their calibration. A high-accuracy system for calibrating Rogowski coils at continuous AC currents was previously developed at NRC. However, in AC resistance welding, high pulsed currents are used. A new calibration system was developed to calibrate current sensors and related equipment under high pulsed currents.
{"title":"Calibration of Rogowski Coils at High Pulsed Currents","authors":"B. Djokic","doi":"10.51843/wsproceedings.2013.01","DOIUrl":"https://doi.org/10.51843/wsproceedings.2013.01","url":null,"abstract":"Calibration of Rogowski Coils at High Pulsed Currents. The many applications of Rogowski coils include their use as current sensors in AC resistance welding. Weld quality depends on monitoring/controlling the welding currents. The accuracy of these current sensors matters, and so does the accuracy of their calibration. A high-accuracy system for calibrating Rogowski coils at continuous AC currents was previously developed at NRC. However, in AC resistance welding, high pulsed currents are used. A new calibration system was developed to calibrate current sensors and related equipment under high pulsed currents.","PeriodicalId":445779,"journal":{"name":"NCSL International Workshop & Symposium Conference Proceedings 2013","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132570875","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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