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Metrology

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Displaying 501 - 525 of 2718

Redressing grievances with the treatment of dimensionless quantities in SI

October 3, 2017
Author(s)
David W. Flater
The International System of Units (SI) and its associated methods adhere to a design principle in which all kinds of quantities are described in terms of a standard set of dimensions. It is a corollary of that principle that quantities having no extent in

Phase noise generated by vibration of bacteria adhered to a quartz resonator

September 22, 2017
Author(s)
Ward L. Johnson, Danielle C. France, F L. Walls, William T. Cordell, Nikki S. Rentz
An approach is presented for sensing mechanical fluctuations of bacteria, with potential application in monitoring microbial responses to changes in chemical environment, such as antimicrobial intervention. Bacteria are tethered to a quartz crystal

Calorimetric Determination of Enthalpies of Vaporization

September 12, 2017
Author(s)
Eugene Paulechka, Dzmitry H. Zaitsau
A review of calorimeters and experimental procedures used for measurement of enthalpies of vaporization for pure liquids is presented. The calorimetric approaches that are illustrated give an insight into direct determination of enthalpies of vaporization

Verification of Calibration Methods for Determining Photon-Counting Detection Efficiency using Superconducting Nano-Wire Single Photon Detectors

September 4, 2017
Author(s)
Igor Vayshenker, Robert D. Horansky, John H. Lehman, Malcolm G. White, Sae Woo Nam, Ingmar Mueller, Lutz Werner, G. Wuebbeler
In the recent years several ways to radiometrically calibrate optical fiber-coupled detectors have been developed. However, fiber-coupled calibration methods for single photon detectors have not been compared by national metrology institutes validating the

Metrology Outreach and Training: A Fulbright Experience in Mexico

August 30, 2017
Author(s)
Georgia L. Harris, Flora Mercader, Adriana Veraza, Salvador Echeverria Villagomez
2016 was an exciting year for international collaboration on metrology education and training. This paper provides a 3-part look at how a Fulbright Specialist grant supported collaboration between the United States and Mexico. Part 1 describes the

Surface interaction parameter measurement of solvated polymers via model end-tethered chains

August 11, 2017
Author(s)
Richard J. Sheridan, Sara V. Orski, Ronald L. Jones, Sushil K. Satija, Kathryn L. Beers
We present a method for the direct measurement of the relative energy of interaction between a solvated polymer and a solid interface. By tethering linear chains covalently to the surface, we ensured the idealized and constant configuration of polymer

Continuous Laser Scan Strategy for Faster Build Speeds in Laser Powder Bed Fusion System

August 9, 2017
Author(s)
Ho Yeung, Brandon Lane, Jason Fox, Felix Kim, Jarred C. Heigel, Jorge Neira
Research has shown significant influence of laser scan strategy on various part qualities in the laser powder bed fusion additive manufacturing process. The National Institute of Standards and Technology developed the Additive Manufacturing Metrology

Submillimeter Wavelength Scattering from Random Rough Surfaces

August 9, 2017
Author(s)
Erich N. Grossman, Richard A. Chamberlin, David R. Novotny, Joshua A. Gordon, Nina P. Basta
We describe bistatic scattering measurements on eight reference targets constructed from Al 2O 3 grit of various sizes embedded in an absorptive epoxy matrix. These samples' surface topographies were measured using focus-variation microscopy, and their

SEM/EDS Trace Analysis: Limits Imposed by Fluorescence of the Detector

August 4, 2017
Author(s)
Dale E. Newbury, Nicholas W. Ritchie, Michael J. Mengason, Keana C. Scott
Elemental trace analysis by electron-excited x-ray spectrometry performed in the scanning electron microscope (SEM) with energy dispersive x-ray spectrometry (EDS) can reach a limit of detection of 0.0005 mass fraction for many elements. Exceptions include
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