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Metrology

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Displaying 1026 - 1050 of 2718

Liquid Piston Prover Uncertainty Analysis Spreadsheet

March 25, 2014
Author(s)
John D. Wright, Aaron N. Johnson, Jodie G. Pope
This publication is a spreadsheet that calculates the mass and volume flow uncertainty for a piston prover liquid flow standard based on user inputs of component uncertainties. The calculations use the basis equation and uncertainty analysis presented in

Bootstrap Variability Studies in ROC Analysis on Large Datasets

March 19, 2014
Author(s)
Jin Chu Wu, Alvin F. Martin, Raghu N. Kacker
The nonparametric two-sample bootstrap is employed to compute uncertainties of measures in receiver operating characteristic (ROC) analysis on large datasets in areas such as biometrics, and so on. In this framework, the bootstrap variability was

Performance of Coriolis Meters in Transient Gas Flows

March 17, 2014
Author(s)
Jodie G. Pope, John D. Wright
NIST evaluated the instantaneous and totalized flow measured by two commercial coriolis meters under transient flow, pressure, and temperature conditions using a Transient Flow Facility (TFF) developed for this purpose. During a simulated cascade fill of a

Are Bragg Peaks Gaussian?

March 12, 2014
Author(s)
Boualem Hammouda
It is common practice to assume that Bragg scattering peaks have Gaussian shape. The Gaussian shape function is used to perform instrumental smearing corrections. Using Monte Carlo ray tracing simulation, the resolution of a realistic small-angle neutron

Controlled Formation and Characterization of Dithiothreitol-Conjugated Gold Nanoparticle Clusters

March 5, 2014
Author(s)
De-Hao D. Tsai, Tae Joon Cho, Frank W. DelRio, Justin Gorham, Jiwen Zheng, Jiaojie Tan, Michael R. Zachariah, Vincent A. Hackley
We report a systematic study of the controlled formation of discrete-size gold nanoparticle clusters (GNCs) by interaction with the reducing agent dithiothreitol (DTT). Asymmetric-flow field flow fractionation and electrospray differential mobility

How to weigh everything from atoms to apples using the revised SI

March 3, 2014
Author(s)
Jon R. Pratt
The fact that the unit of mass might soon be derived from the Planck constant, rather than from an artifact standard, can seem daunting and downright baffling when viewed from the vantage point of our day to day perception of mass. After all, at

Certification of Total Arsenic in Blood and Urine Standard Reference Materials by Radiochemical Neutron Activation Analysis and Inductively Coupled Plasma Mass Spectrometry

March 1, 2014
Author(s)
Rick L. Paul, William C. Davis, Karen E. Murphy, Colleen E. Bryan Sallee, Lee L. Yu, William F. Guthrie, Dennis D. Leber, Thomas W. Vetter
A newly developed procedure for determination of arsenic by radiochemical neutron activation analysis was used to measure arsenic in SRM 955c Toxic Elements in Caprine Blood and SRM 2668 Toxic Elements in Frozen Human Urine for the purpose of providing

Methods for improving visibility measurement standards of powered industrial vehicles

February 28, 2014
Author(s)
Roger V. Bostelman, Jochen Teizer, Soumitry J. Ray, Mike Agronin, Dominic Albanese
Poor visibility of powered industrial vehicles, such as forklifts, used in industry is often the cause of accidents that include pedestrians. Current standards allow up to 20% non-visible regions for forklifts where measurement of these regions is

In situ temperature measurements for selective epitaxy of GaN nanowires

February 17, 2014
Author(s)
Kristine A. Bertness, Matthew D. Brubaker, Todd E. Harvey, Shannon M. Duff, Aric W. Sanders, Norman A. Sanford
We demonstrate with spatially resolved, in situ temperature measurements and ex situ reflectance measurements that differences in appearance for masked and unmasked surfaces on patterned growth substrates arise from wavelength-dependent emissivity

Metrological challenges introduced by new tolerancing standards

February 13, 2014
Author(s)
Ed Morse, Yue Peng, Vijay Srinivasan, Craig M. Shakarji
The recent release of ISO has provided designers with a richer set of specification tools for the size of part features, so that various functional requirements can be captured with greater fidelity [2]. However, these tools also bring new challenges and

Estimation of uncertainty in application profiles

February 3, 2014
Author(s)
David W. Flater
Application profiling tools are the instruments used to measure software performance at the function and application levels. The most powerful measurement method available in application profiling tools today is sampling-based profiling, where a

Estimation of the Limit of Detection Using Information Theory Measures

January 31, 2014
Author(s)
Alexander (. Vergara Tinoco, Fonollosa Jordi, Huerta Ramon, Santiago Marco
Definitions of the Limit of Detection (LoD) based on the probability of false positive and/or false negative errors have been proposed over the past years. Although such definitions are straightforward and valid for any kind of analytical system, the

Saponins: A sustainable surfactant. From its microwave-assisted extraction to the synthesis of monodisperse latices

January 21, 2014
Author(s)
Charlene Schnitt, Bruno Grassl, Julien C. Gigault, Vincent A. Hackley, Gaetane Lespes, Jacques Desbrieres, Virginie Pellerin, Stephanie Reynaud
Synthetic surfactants are widely used in emulsion polymerization, but it is increasingly desirable to replace them with naturally derived molecules with a reduced environmental burden. This study demonstrates the use of saponins as sustainable and

SPRITE: A modernized approach to scanning probe contact resonance imaging

January 20, 2014
Author(s)
Anthony B. Kos, Jason P. Killgore, Donna C. Hurley
We describe a system for contact resonance tracking called Scanning Probe Resonance Image Tracking Electronics (SPRITE). SPRITE can image two contact resonance frequencies simultaneously and thus can be used to acquire quantitative mechanical properties

Acoustic Gas Thermometry

January 16, 2014
Author(s)
Michael R. Moldover, Roberto M. Gavioso, James B. Mehl, Laurent Pitre, Michael de Podesta, Jintao Zhang
Primary acoustic gas thermometry (AGT) exploits the simple relationship between the speed of sound in a dilute gas u and the thermodynamic temperature T of the gas. For monatomic gases such as argon and helium, u2 = (5/3) kT/m, in the limit of zero

Liquid Flow Meter Calibrations with the 0.1 L/s and 2.5 L/s Piston Provers

January 15, 2014
Author(s)
Jodie G. Pope, John D. Wright, Aaron N. Johnson, Christopher J. Crowley
This document provides a description of the 2.5 L/s and 0.1 L/s liquid flow calibration standards operated by the National Institute of Standards and Technology (NIST) Fluid Metrology Group to provide flow meter calibrations for customers. The 0.1 L/s and

Fast and Reliable Spectral Response Measurements of PV Cells Using Light Emitting Diodes

January 1, 2014
Author(s)
Behrang H. Hamadani, John F. Roller, Brian P. Dougherty, Howard W. Yoon
We present a measurement system for absolute differential spectral responsivity of solar cells based on high-powered LED arrays coupled to an optical light guide capable of large area illumination. Two different measurement techniques were developed and
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