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Measure Articles 2015 (29)

 
Picture of the productA New Test System for Measuring RF Sources and Receivers
Michael Dobbert
A new test system has been developed that uses a vector network analyzer (VNA) to make RF and microwave S-Parameter, power accuracy, power linearity, harmonic distortion, intermodulation distortion, phase noise, and frequency accuracy measurements. The test system, which includes fixturing to allow connecting various devices under test (DUTs), has been deployed in a manufacturing test environment. Measurement uncertainties take into account the expected temperature range of the manufacturing environment, the impact of the fixturing, and the expected uncertainties from the measuring equipment. The environmental and fixturing characterizations were determined by repeatedly calibrating the vector network analyzer under various environmental conditions, and then analyzing the variability of the measured values when correcting for multiple calibrations. This paper discusses the test system design, the characterization of the fixturing, the effects of temperature, and the validation of the calibration process. The paper also provides a detailed discussion of power accuracy measurements.


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MS15_04_DOBB
Picture of the productA Study of Factors that Influence Micropipette Calibrations
Elsa Batista, Nelson Almeida, and Eduarda Filipe
The gravimetric method is normally used in the calibration of micropipettes, based on ISO 8655 and ISO 4787. In order to verify the influence of specific experimental details of the normalized procedure described in ISO 8655-6 (and others not described in the standard) on the delivered volume of a micropipette, several experimental tests wereperformed by the Volume Laboratory (LVO) of The Portuguese Institute of Quality (IPQ). These tests include the angle variation of aspiration and delivery of liquid, the immersion depth of the tip, aspiration and delivery time, the type of tip and altitude. The results verified that the amount of liquid delivered from a micropipette depends on very specific conditions. Some of the more relevant conclusions of this experimental study were that the delivered volume can be lower than expected if the delivery angle is larger than 60º and also if the laboratory is working at high altitudes. Higher than expected volumes can be delivered if the micropipette is immersed too deeply (more than 3 mm) into the liquid and the aspiration time is too long (> 8 s).


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MS15_01_BATIST
Picture of the productAn Analysis of ISO/IEC 17025 Nonconformities Reported
Morgana Pizzolato, Francine de Brito Nagel, and Filipe Medeiros Albano
This paper presents an analysis of nonconformities found when auditing testing and calibration laboratories in accordance with ISO/IEC 17025. The auditing was conducted by auditors from Rede Metrológica RS (RMRS), a nonprofit technical association in Brazil. The objective of this study was to identify the ISO/IEC 17025 requirements that have the highest number of non-conformities. We collected data from about 500 laboratory audits performed during the five-year period from 2008-2012. Data were analyzed by grouping the laboratories by calibration and test area, by ISO/IEC 17025 requirements, and by year. The calibration areas were: acoustic, length, electricity, force, torque and hardness, mass, optical, pressure, flow and level, temperature and humidity, time and frequency, viscosity, and volume. The testing areas were: chemistry and physical chemistry, microbiological, biological and toxicological, mechanical, and biochemistry. We considered separately the percentages of nonconformities in technical and management requirements. We also present data showing the trend of nonconformities obtained during five years of assessments.


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MS15_02_PIZZ
Picture of the productApplication of Cost Effective Enclosures to Reduce Environ.
Pieter Greeff
Length measurements are always affected by environmental conditions, of which temperature is typically a major concern. This concern can be addressed by applying error correction, uncertainty estimation, or environmental control. Control can be achieved by controlling the whole laboratory, but this can be expensive. Custom built enclosures around individual instruments, however, offers a cost effective alternative. Two different dimensional measurements (roundness and gauge blocks by interferometry) are used as examples to investigate this in a practical sense, since both are significantly influenced by the environment. This paper will focus specifically on the deviation from the reference temperature and environmental stability. The results obtained by subsequent implementation of control and isolation enclosures will be presented. Here a prototype gauge block temperature control chamber design reduced the temperature range of the measurement volume from ±1 °C to ±0.1 °C, while the introduction of a roundness enclosure reduced probe drift by 96 %.


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MS15_02_GREEF
Picture of the productCalibration of Defibrillator Analyzers
Steven Yang and Aaron Y.K. Yan
The Standards and Calibration Laboratory (SCL) in Hong Kong has set up a calibration facility for defibrillators and defibrillator analyzers. Defibrillators are medical devices designed to resume the normal heart pulse of a patient by discharging energy pulses to a person who is suffering from an emergency cardiac attack. They are commonly used in hospitals and medical institutes. At the SCL, the energy delivered by a defibrillator is measured using a high quality digital sampling system. The system includes a high voltage divider, a sampling voltmeter, an impedance analyzer, and a control computer. The sampled voltage waveform is digitally processed to derive the delivered energy. The system can also be used to check the accuracy of a defibrillator analyzer. The sampling system and its signal processing are described in this paper. To ensure the accuracy of the sampling system, it is calibrated against the laboratory’s voltage and time reference standards. A standard waveform with calculable energy is used to verify the sampling system. It is shown that the system can achieve an energy measuring uncertainty of better than 0.7 %.


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MS15_04_YANG
Picture of the productCalibration of Optical Fiber Laser Sources
Samuel C. K. Ko, Aaron Y. K. Yan, and Barry K. Y. Chan
A calibration system for optical fiber laser sources has been developed at the Government of the Hong Kong Special Administrative Region Standards and Calibration Laboratory (SCL). The measurements of wavelength, output power level and output power stability of optical fiber laser sources fitted with fiber channel/angled physical contact (FC/APC) connectors are detailed. The wavelength is directly measured by the laboratory wavelength meter. The standard measurement uncertainty obtainable by this calibration method is less than 1 picometer (pm). The output power is the summation of the measured power by the laboratory’s electrically calibrated pyroelectric radiometer (ECPR), and the insertion loss between the source and the ECPR with a standard measurement uncertainty of about 3.7 %. The output power stability is evaluated by measuring the maximum and minimum fluctuation of the measured optical power using the laboratory ECPR which has three significant digits of resolution.


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MS15_01_KO
Picture of the productCalibration of Weighing Instruments: Measurement Uncertainty
Klaus Fritsch and Ian Ciesniewski
The calibration of non-automatic weighing instruments (NAWIs) is one of the key activities in quality control and in the production area that needs to be carried out rigorously in order to accomplish pre-defined quality attributes of a weighing process. Many misconceptions and ambiguities with regards to efficient calibration of balances and scales have been prevalent in the industry for many decades. There are recent activities in the scientific community to address this issue by creating a harmonized approach for calibration of NAWIs that is based on an internationally recognized calibration guideline. This approach goes beyond traditional calibration as it addresses not only the performance of the instrument at calibration, but also provides guidance to estimate the uncertainty during day-to-day use. This approach has significant practical importance as it facilitates the assessment of the equipment’s performance against user specific weighing tolerance requirements. One of the most important implications is the definition of the so-called minimum weight and the safe weighing range, which is derived from the uncertainty in use. Weighing quantities in the safe range of the instrument ensures adherence to user-specific weighing tolerance requirements, and thus fosters compliance with the pre-defined quality attributes of a weighing process.


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MS15_03_FRITS
Picture of the productColor Mark Sensor Calibration System for Timing Devices
Ahmad Sahar Omar, Mohd Fauzi Othman, Mohd Nasir Zainal Abidin, and Erik F. Dierikx
A patent pending calibration system for timing devices with a seven-segment liquid crystal display (LCD) is presented in this paper. The prototype calibration system uses a color mark sensor, a gate controller, a toggle switch, and dual counters. It operates by directing the light spot of the color mark sensor onto an identified segment of the seven-segment LCD. When the device under test is running, the signal output from the color mark sensor, depending on the state of the chosen segment, will trigger the toggle switch to start or stop the counters to count the pulses of the 1 kHz reference frequency. By means of the toggle switch, the first counter will stop counting when the second counter starts counting, and vice versa, without halting the counting processes; thus, eliminating the elapsed time between the measurement readouts reported by the dual counters. The experimental results and bilateral comparisons showed that the new calibration system based on this technique has a measurement uncertainty of 6.8 × 10-8.


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MS15_02_SAHAR
Picture of the productDetermination of Emissivity by Use of Reflected Thermal Rad.
Frank Liebmann
The determination of emissivity is crucial in any temperature measurement using radiation thermometry. Without this knowledge, large measurement uncertainties result. There is a lack of information on emissivity for common materials. When databases are available, they often give emissivity for a specific material in a range or give emissivity for different conditionings of the material. This information may not apply to certain uses of the material, creating considerable doubt for anyone making measurements in the field. Therefore, a method to determine emissivity for a material object in the field is needed. In 2011, Yamada and Ishii discussed a method that was set up in a fixed geometry to determine the emissivity of a specular object. In this paper, a method is discussed to determine the emissivity of both specular and diffuse objects using a thermal radiation source. The paper presents the theory plus assumptions that were made. It then discusses practical measurements that were made to verify these assumptions. These measurements are then compared to emissivity determined by other methods.


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MS15_01_LIEBM
Picture of the productEstablishing a Traceability Chain for Sound Pressure
Naveen Garg
This paper discusses the establishment and assessment of metrological traceability, including the provision of metrological references by a metrological institutional framework and the role of inter-laboratory comparisons, in the realization of the units of sound pressure level and vibration amplitude. The paper discusses the national primary and secondary standards maintained at CSIR-NPL, India for acoustic and vibration metrology; the validation of the Calibration and Measurement capabilities (CMCs) through participation in key comparisons with other national metrology institutes, and the establishment of traceability chain for government and industrial laboratories located throughout India. The work presented here describes how the measurement uncertainty of the primary and secondary standards has been reduced. It also describes a measurement chain that disseminates the units of sound pressure and vibration from the national level to industry with only a small degradation in measurement uncertainty.


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MS15_01_GARG
Picture of the productEstimating Thermal Effects for Granite Surface Plate Calib.
Gordon A. Skattum
This paper explores the sources of variation and thermal effects applied to granite surface plate calibration, and their impacts on the quality, uncertainty, and appropriate decisions about when to resurface. It will also address ASME B89.3.7-2013 and provide an approach for estimating uncertainty components due to the temperature related sources. The components, especially temperature stability, are always present and can significantly affect or dominate measurement uncertainty in the calibration of overall flatness. Examples will demonstrate that thermal effects should be included in any uncertainty analysis for the calibration of overall flatness. An important and ongoing effort related to this paper is to research, identify and document current industry practices and provide guidelines for the “best practice” calibration of granite surface plates.


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MS15_01_SKATT
Picture of the productEutectic Ga-In Melting-Point Blackbody for Radiation Therm.
Veronica Sastre-Muñoz and Daniel Cárdenas-García
The Radiation Thermometry Group at the Centro Nacional de Metrología (CENAM) is presently working with low-temperature fixed-point blackbodies to study their suitability for calibration and verification of radiation thermometers. The International Temperature Scale of 1990 specifies two fixed points in the 0 ºC to 30 ºC temperature range: the triple point of water and the melting point of gallium. We designed a eutectic Ga-In melting-point blackbody that could serve as a good candidate as a third fixed-point in the middle of those fixed points. The measured radiance temperature of the eutectic Ga-In melting-point blackbody was 15.67 ± 0.10 ºC (k = 1).


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MS15_04_SASTRE
Picture of the productEvaluating Dense 3D Surface Reconstruction Techniques
Isabella Toschi, Jean-Angelo Beraldin, Luc Cournoyer, Livio De Luca, and Alessandro Capra
This paper discusses an approach for evaluating the accuracy of dense 3D surface reconstruction techniques based on images. So far, the emergence of these novel techniques has not been supported by the definition of an internationally recognized standard which is fundamental for user confidence and market growth. In order to provide an element of reflection and solution to the different communities involved in image-based 3D modeling, we present an approach for the assessment of the metric performance of an open-source set of routines for bundle block adjustment and dense image matching (Apero/MicMac). The evaluation is performed using a metrological approach, through comparisons between image-based 3D generated data and ´reference’ data acquired with two hemispherical laser scanners, one total station, and one laser tracker. Aspects of traceability and measurement uncertainty of all these reference 3D data are discussed. The methodology is applied to two case studies, tailored to analyze the software capabilities in dealing with both outdoor and environmentally controlled conditions. Comparative data and accuracy evidence provided by both tests allow the study of some key factors affecting 3D model accuracy.


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MS15_01_TOSCH
Picture of the productEvaluation of Heat and Moisture Exchanger Performance
Brais Vazquez, Paolo Monticelli, Alessia Nicosia, Gianni Santachiara, and Franco Belosi
This paper presents a new test apparatus for the evaluation of the humidification efficiency of heat and moisture exchangers (HMEs). These devices are widely used in invasive ventilation conditions to humidify and to heat medical gases inhaled by the patients. The new custom-made test apparatus allows simultaneous measurements with the two most common methods for in vitro tests: gravimetric, which is considered the reference method by the international standard ISO 9360, and hygrometric. In the reference method, the absolute humidity of the inhaled gas (HME moisture output) is determined by subtracting, from the absolute humidity of the exhaled gas (AHexh), the moisture loss measured with a precision balance. Consequently, AHexh is supposed to be stable throughout the test. In addition, ISO 9360 does not set a limit for the maximum value of AHexh in the measuring process. In the new experimental test apparatus, AHexh is constantly monitored and the humidification efficiency of an HME is expressed as the ratio of the HME moisture output with respect to AHexh, the so-called relative efficiency. Results show that average values of AHexh and of the relative efficiency are very similar with both methods, confirming the reliability of the new test apparatus.


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MS15_02_VAZQ
Picture of the productFiber Bragg Grating Based Thermometry
Zeeshan Ahmed, James Filla, William Guthrie, and John Quintavalle
In recent years there has been considerable interest in developing photonic temperature sensors such as the Fiber Bragg gratings (FBG) as an alternative to resistance thermometry. In this study we examine the thermal response of FBGs over the temperature range of 233 K to 393 K. We demonstrate, in a hermetically sealed dry Argon environment, that FBG devices show a quadratic dependence on temperature with expanded uncertainties (k = 2) of .500 mK. Our measurements indicate that the combined measurement uncertainty is dominated by uncertainty in determining the peak center fitting and by thermal aging of polyimide coated fibers.


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MS15_04_AHMED
Picture of the productFiber Bragg Gratings Embedded in 3D-Printed Scaffolds
Peter C. Liacouras, Gerald T. Grant, Khazar Choudhry, Gregory F. Strouse, and Zeeshan Ahmed
In recent years there has been considerable interest in utilizing embedded fiber optic based sensors for fabricating smart materials. One of the primary motivations is to provide real-time information on the structural integrity of the material so as to enable proactive actions that prevent catastrophic failure. In this preliminary study we have examined the impact of embedding on the temperature-dependent response of fiber Bragg gratings (FBG). Our results indicate that scaffold strain has a significant impact on the embedded sensor’s temperature response. Thus, the use of embedded sensors will require the development of in corpus techniques that can calibrate sensors while they are embedded.


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MS15_02_LIACO
Picture of the productLaboratory Activities for a Dimensional Metrology Class
Joseph P. Fuehne
The Purdue College of Technology in Columbus, Indiana recently offered, for the first time, a class in Dimensional Metrology. In keeping with its hands-on, project-based learning philosophy, the class mixes many laboratory activities with the lecture component of the class. The laboratory activities focus on accomplishing some engineering function that requires measurement. These activities are not just a matter of measuring a few items with the supplied tools; there is always a clear engineering or manufacturing objective with each laboratory activity. In some cases, this may also include a reverse-engineering project that incorporates a measure-manufacture-measure iterative cycle to determine the effectiveness of the manufacturing operation. This paper discusses in detail the experiments utilized in the class. Some examples include gage R&R studies, a calibration exercise, determining constants of springs, measuring threads, and measuring gears. The activities are based on the premise that adding realistic and engaging measurement activities to a class better prepares students for careers in product design and manufacturing.


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MS15_02_FUEHNE
Picture of the productMeasured Ionospheric Delay Corrections for Code-based GPS
Victor Zhang and Zhiqi Li
In Global Positioning System (GPS) time transfer measurements, all of the delays in receiving GPS timing signals, including the ionospheric delay in the signal path and the internal delay of a GPS receiver (receiver delay), must either be corrected for or included in the uncertainty analysis. For code-based GPS time transfer with single frequency receivers, the ionospheric delay can be corrected using the Klobuchar model, or using the IGS ionospheric maps. The modeled ionospheric delay correction is most effective during the nighttime hours. The IGS ionospheric map corrections have much smaller uncertainties than corrections from the Klobuchar model, especially during the daytime hours, but the effects of ionosphere variations are still noticeable in the received GPS signals due to the resolution of the map. With the use of dual-frequency multi-channel GPS receivers, the ionospheric delay can be obtained from the receiver’s dual-frequency measurements. The measured ionospheric delay correction removes nearly all of the ionospheric delays from the GPS time measurements. However, the receiver delay for the measurements on both the L1 and L2 frequencies are used in computing the ionospheric delay, and if the receiver delay is not calibrated or if the delay has changed, the error in receiver delay can propagate to the measured ionospheric delay corrections, and add uncertainty to the time transfer results. Thus, to achieve the lowest possible time transfer uncertainty, it is important to locally monitor receiver delay changes and to periodically calibrate the receiver delay.


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MS15_03_ZHANG
Picture of the productMetrology Survey Applied in Health Care Facilities
Maria do Ceu Ferreira and Ana Sofia Matos
To evaluate the role of metrology in health care facilities, we conducted a study to identify and analyze issues that arise when the concept of metrological traceability is applied to hospital facilities. Survey data were collected from 44 Portuguese hospitals. The results allowed us to identify some key metrological indicators that pertain to hospitals, and to conclude that metrological traceability is absent from the daily considerations of health care professionals and facilities.


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MS15_01_FERREI
Picture of the productNew Techniques and Methods for Managing Measurement Risk
Teruhisa Tsuru
Murata Manufacturing Co., Ltd. produces many kinds of electronic products in very large quantities, and utilizes management techniques and methods for the measurement of risk in the inspection process to guarantee the quality of these products. The AQL (Acceptable Quality Level) technique was used in production as a general sampling technique in production, but this method could not guarantee consumer’s risk in the lot. The LTPD (Lot Tolerance Percent Defective) improves upon AQL by guaranteeing consumer’s risk in the lot. However, LTPD requires a sample size more than 10 times larger than AQL. To solve this problem, we have developed a new sampling technique and method that allows a decrease in the number of required samples. It also allows us to reduce the probability, in which the consumer’s risk of the lot is greater than the designated consumer’s risk, to less than 37.5 parts per million (ppm). This paper explains the new risk calculation and sampling techniques in detail.


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MS15_03_TSURU
Picture of the productOptimizing Data Logger Setup and Use for Refrigerated Vac.
Michal J. Chojnacky, L. F. Chaves Santacruz, W. Wyatt Miller, and Gregory F. Strouse
Accidental freezing of refrigerated vaccine represents a significant public and private healthcare cost. Freeze-damaged vaccines lose their effectiveness, putting public health at risk. U.S. immunization programs have strengthened vaccine storage and handling recommendations to mitigate this danger. However, current publications describing the setup and configuration of vaccine temperature monitoring devices allow for a range of untested interpretations. In this paper, we report on our study of specific temperature monitoring setup variables, including vial size, thermal buffer type, buffer fluid concentration, and placement of the probe-in-vial setup, in an effort to provide definitive guidance on the selection of an optimal temperature monitoring setup and methodology for use in vaccine storage refrigerators.


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MS15_03_CHOJN
Picture of the productResolving Resolution Uncertainty
Mark Kuster
ANSI/NCSLI Z540.3 redefined the “test uncertainty ratio” (TUR) measurement quality metric as a ratio of maximum permissible error to measurement process uncertainty. The definition engendered some immediate and lingering disagreement. Much of this disagreement stems from inconvenience, because including uncertainty components from the unit under test (UUT) may cloud conformity assessments when an instrument’s maximum permissible error (MPE) specification falls near its repeatability or resolution limits. The TUR then apparently loses its value as a simple measurement process validation. Some practitioners view UUT error contributions as a simple reality to address in calibration processes, others consider such inclusions, at least in some circumstances, a logical fallacy. Unfortunately, differing opinions also arise between laboratory assessors and, by implication, between accreditation bodies. This paper neutrally reviews the problem from first principles and evaluates the two positions in terms of metrological compatibility and measurement decision risk. The paper also discusses mitigation methods.


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MS15_03_KUST
Picture of the productSummary of Outside Micrometer Calibration Proficiency Test.
Yi-Ting Chen, Paul Kam-Wa Lui, Pin-Hao Wang, and Chen-Yun Hung
Proficiency testing is an established way to demonstrate a laboratory’s measurement capabilities. Accredited laboratories are usually requested to participate in proficiency testing conducted by the laboratory accreditation organizations in their countries. The Center for Measurement Standards / Industrial Technology Research Institute (CMS/ITRI) has long been committed to measurement technologies and statistical engineering in Taiwan and is one of the Proficiency Testing Providers (PTPs), with an accreditation number of P002, accredited by Taiwan Accreditation Foundation (TAF). This paper summarizes the results of a 2014 outside micrometer calibration proficiency testing scheme, number PT2014-KA02, held in Taiwan. Twentyfive TAF accredited calibration laboratories participated in the proficiency testing, and the |En| values of each participating laboratory are smaller than one. This implies that all the participants’ results are satisfactory with respect to each other and that the measurement capabilities of laboratories performing micrometer calibrations are very consistent in Taiwan.


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MS15_04_CHEN
Picture of the productThe 2014 North American Josephson Voltage Comparisons
Jonathan Harben, Yi-hua Tang, Harold Parks, and James Wachter
The 10th North American Josephson voltage standard (JVS) interlaboratory comparison (ILC) at 10 V was completed in 2014. This ILC was unique because it consisted of two parts. An on-site comparison was conducted between the National Institute of Standards and Technology (NIST) transportable JVS and the pivot laboratory’s conventional JVS (CJVS) system. A set of four traveling Zener voltage standards then served to transfer traceability from the pivot laboratory to the 12 other participants. In addition to the regular ILC activities, a second on-site comparison was conducted between the NIST transportable JVS and the programmable JVS (PJVS) provided by the National Aeronautics and Space Administration (NASA). Due to limited availability of the PJVS, only two laboratories were selected to make direct comparisons between their CJVS systems and NASA’s PJVS. The method has been used for the first time in the JVS ILC and has the advantage of using the PJVS as a transfer standard. This allowed the participating laboratory to make comparisons using its CJVS system against the 10 V PJVS in the same manner as the measurements for Zener standards are performed while overcoming limitations of the Zener noise. Results of the 2014 ILC are provided in this paper.


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MS15_04_HARB
Picture of the productThe NIST Uncertainty Machine
Thomas Lafarge and Antonio Possolo
The NIST Uncertainty Machine (http://uncertainty.nist.gov) is a web-based software application produced by the National Institute of Standards and Technology (NIST) to evaluate the measurement uncertainty associated with a scalar output quantity that is a known and explicit function of a set of input quantities for which estimates and evaluations of measurement uncertainty are available. Input and output quantities are modeled as random variables and their probability distributions are used to characterize measurement uncertainty. The NIST Uncertainty Machine implements the approximate method of uncertainty evaluation described in the “Guide to the expression of uncertainty in measurement” (GUM), and the Monte Carlo method of the GUM Supplement 1 (GUM-S1). The NIST Uncertainty Machine is freely accessible worldwide from any computer connected to the World Wide Web. Using a Web browser, the user specifies all the necessary information in an easy-to-use form. The calculations are performed on a NIST server, which returns the results to the user by posting them on a Web page that is displayed in the user’s browser, and by writing them to files that the user may download. The NIST Uncertainty Machine also produces a conventional uncertainty budget that lists the contributions that the uncertainties associated with the input quantities make to the uncertainty associated with the output quantity. We show how these contributions can be derived from the Monte Carlo samples, and in the process illustrate an interesting and informative fact that conventional uncertainty budgets ignore.


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MS15_03_LAFARG
Picture of the productThe Redefinition of the SI: Impact on Calibration Services
Neil M. Zimmerman, Jon R. Pratt, Michael R. Moldover, David B. Newell, and Gregory F. Strouse
As most readers are probably at least vaguely aware, it is likely that the SI system of units will be redefined in 2018. This redefinition would fundamentally change the logical structure of the SI, with one result being a substantial change in how mass is realized and disseminated within national metrology institutes (NMI’s) such as the National Institute of Standards and Technology (NIST). However, we expect that the only impact on how customers see calibration services will be small step changes that NIST will document and publicize to customers in advance. In this article, we list the main areas of calibration services at NIST, describe how for most of them there will be negligible impact, discuss the impact on mass and DC electrical calibrations, and explain our best predictions as to how we expect NIST to make a seamless transition for customers in those two areas.


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MS15_02_ZIMM
Picture of the productTraceability Considerations for the Characterization and Use
Charles D. Ehrlich
There are several different ways that measuring systems (which include measuring instruments) can be characterized, including calibration, adjustment, and verification (or testing). Common elements of such characterizations include comparisons of indicated values with values obtained when using measurement standards, specification of influence quantities and operating conditions, and statements of system resolution and repeatability. Differing elements of such characterizations include whether or how measurement uncertainty is recorded during the characterization, whether any change is made to the measuring system (including in hardware and software) during the characterization process, and whether recording the measured error of indication is part of the characterization process. The way that a measuring system is characterized will typically influence how measurement results are obtained and stated when subsequently using the measuring system to perform measurements. Because a measurement result includes the measurement uncertainty as well as the measured value, the metrological traceability that is ascribed to measurement results obtained when using such characterized measuring systems can be impacted by the type of characterization that was performed. When calibration, adjustment, or verification of a measuring system results in being able to obtain explicit measurement uncertainties when using the system, metrological traceability is ensured. However, for some types of verification (or testing), such as when Test Accuracy Ratios (TARs) or Test Uncertainty Ratios (TURs) are used, the measurement result does not typically contain an explicit measurement uncertainty, which brings the metrological traceability into question. This paper takes a preliminary look at how metrologically traceable measurement results, including associated uncertainties, might be obtained in this latter case.


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MS15_04_EHRLICH
Picture of the productUncertainty Evaluation of the Calibration of Dial Indicator
Paul Kam-Wa Lui, Huay-Chung Liou, Wei-Cheng Chang, and Huang-Chi Huang
This paper describes the uncertainty evaluation procedure for a dial indicator calibrator calibration in accordance with the ISO/IEC Guide 98-3:2008. The effects of error sources on this calibration are analyzed to estimate the corresponding standard uncertainties and sensitivity coefficients. The combined standard uncertainty and effective degrees of freedom are then calculated. The coverage factor can be found by taking the t-factor corresponding to the effective degrees of freedom. Finally, the expanded uncertainty can be obtained by multiplying the coverage factor and the combined standard uncertainty. The calibration method of the dial indicator calibrator is also briefly described. For the calibration of a dial indicator calibrator with a resolution of 0.1 ìm in the measurement range of (0 to 60) mm, the expanded uncertainty is estimated to be 0.81 ìm (k = 2.05, 95 % confidence level).


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MS15_04_KAM
Picture of the productVoltage Metrology Using a Quantum AC Standard
Thomas E. Lipe, Joseph R. Kinard, Yi-hua Tang, Samuel P. Benz, Charles J. Burroughs, and Paul D. Dresselhaus
We report on the use of a quantum-based AC voltage standard for ac-dc difference metrology at the National Institute of Standards and Technology (NIST). The paper describes the characterization of the output transmission line and the methods used to correct for its errors, the use of the quantum standard in voltage scaling to calibration thermal transfer standards, and its use in the NIST calibration services for thermal voltage converters at frequencies up to 100 kHz. Plans for future use are also presented.


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MS15_03_LIPE