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Displaying 201 - 225 of 2714

NIST Handbook 44: Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices (2023 Ed.)

January 30, 2023
Author(s)
Tina Butcher, Richard A. Harshman, Gloria Lee, Juana Williams, Jan Konijnenburg, Lisa Warfield, Katrice Lippa, Shelby Bowers, Elizabeth Benham
NIST Handbook 44 includes specifications, tolerances, and other technical requirements for weighing and measuring devices. These requirements are intended to encourage the design, installation, testing, and use of weighing and measuring devices that

Measurement of Transient Environmental Effects in GPS-Disciplined Clocks

January 23, 2023
Author(s)
Andrew Novick, Michael A. Lombardi, Demetrios Matsakis, John Clark
GPS-disciplined clocks (GPSDCs) are designed to optimize the accuracy and stability of their pulse-per-second (PPS) and frequency outputs by steering an internal oscillator to the timing solution from a GPS receiver based on the received satellite signals

What does the pixel measure?

January 11, 2023
Author(s)
David W. Flater
The pixel is often used as a unit of measurement in information technology. Unfortunately, there is not a simple, consistently-applicable answer to what it is a measure of. This report analyzes the pixel unit through the lens of metrology and shows how one

Dealing with counts and other quantal quantities in quantity calculus

January 1, 2023
Author(s)
David W. Flater
Continuity is usually assumed as a defining feature of measured quantities. This premise is false for counted quantities, amount of substance, electric charge, and others that are constrained to exist in integral multiples of a quantum. A software

Isotope Dilution Mass Spectrometry as an Independent Assessment for Mass Measurements of Milligram Quantities of Aqueous Solution

January 1, 2023
Author(s)
Richard Essex, Jacqueline L. Mann, Denis E. Bergeron, Ryan P. Fitzgerald, Svetlana Nour, Gordon A. Shaw, R. Michael Verkouteren
Isotope dilution mass spectrometry was used to independently assess the accuracy of mass measurement methods developed to quantitatively dispense milligram quantities of aqueous solution. Solutions of isotopically enriched 158Gd and enriched 155Gd were

Precise Quantum Measurement of Vacuum with Cold Atoms

December 20, 2022
Author(s)
Daniel Barker, Bishnu Acharya, James A. Fedchak, Nikolai Klimov, Eric Norrgard, Julia Scherschligt, Eite Tiesinga, Stephen Eckel
We describe the cold-atom vacuum standards (CAVS) under development at the National Institute of Standards and Technology. The CAVS measures pressure in the ultra-high and extreme-high vacuum regimes by measuring the loss rate of sub-millikelvin sensor

Crystallization Kinetics in an Immiscible Polyolefin Blend

December 12, 2022
Author(s)
Derek Huang, Anthony Kotula, Chad R. Snyder, Kalman Migler
Motivated by the problem of brittle mechanical behavior in recycled blends of high density polyethylene (HDPE) and isotactic polypropylene (iPP), we employ optical microscopy, rheo-Raman, and differential scanning calorimetry (DSC) to measure the

Determination of the Gravitational Constant Using a BIPM Balance

December 12, 2022
Author(s)
Stephan Schlamminger, Leon Chao, Vincent Lee, David B. Newell, Clive Speake
With the torsion balance developed at the Bureau International des Poids et Mesures (BIPM), the Newtonian constant of gravitation, $G$, can be measured with two methods. In the Cavendish method, the external gravitational torque is obtained from the

Development of an Improved Standard Reference Material for Folate Vitamers in Human Serum

December 12, 2022
Author(s)
Johanna Camara, Jeanita Pritchett, Yasmine Daniels, Mary Bedner, Michael Nelson, Mark Lowenthal, Zia Fazili, Christine Pfeiffer, Karen W. Phinney, Katherine E. Sharpless, Lane C. Sander, Katrice Lippa, James H. Yen, Adam Kuszak, Stephen Wise
The US National Institute of Standards and Technology (NIST) developed a Standard Reference Material® (SRM®) 3949 Folate Vitamers in Frozen Human Serum to replace SRM 1955 Homocysteine and Folate in Human Serum. The presence of increased endogenous levels

Gas Flow Standards and Their Uncertainty

December 12, 2022
Author(s)
John D. Wright, Aaron Johnson, Michael R. Moldover, Shin-ichi Nakao
We review diverse types of gas flow standards that are used to calibrate other gas flow meters. For each type of standard, we describe the principles of its operation and at least one hardware example. We identify the practical limits of the example's

Cannabis Laboratory Quality Assurance Program: Exercise 2 Moisture Final Report

November 29, 2022
Author(s)
Chuck Barber, Colleen E. Bryan Sallee, Carolyn Burdette, Shaun Kotoski, Melissa M. Phillips, Walter Brent Wilson, Laura Wood
In 2020, NIST launched Cannabis Laboratory Quality Assurance Program (CannaQAP) to improve the comparability of the analytical measurements of cannabis and cannabis-derived products in forensic and cannabis (hemp and marijuana) testing laboratories

DIMENSIONAL METROLOGY IN DETERMINATION OF G WITH BIPM'S TORSION BALANCE

November 7, 2022
Author(s)
Vincent Lee, Stephan Schlamminger, Leon Chao, David B. Newell, Jon Pratt, Craig Shakarji, Clive Speake
This paper discusses the dimensional metrology challenges encountered while performing G measurements using the BIPM torsion balance and our solutions.

Calculation of magnetic forces and torques on the Kibble coil

October 22, 2022
Author(s)
Stephan Schlamminger, Lorenz Keck, Frank Seifert, Leon Chao, Darine El Haddad, Shisong Li
Analytically the force and torques on a coil in a field of magnetic flux density can be calculated one of two ways. The line integral can be conducted along the coil's wire, summing up the differential force contribution. For each differential line segment

2022 NCWM-NIST National Survey on 20 lb LPG (Propane) Cylinders

October 19, 2022
Author(s)
David Sefcik, Katrice Lippa, N. Alan Heckert, Stephen Benjamin, Ivan Hankins, Don Onwiler
The National Conference on Weights and Measures (NCWM) in partnership and cooperation with the NIST Office of Weights and Measures (OWM) and the Weights and Measures Divisions of select U.S. States initiated the 2022 National Survey on 20 lb LPG (Propane)

The Digital NIST: Challenges and opportunities in the digital transformation of NIST's calibration services

September 21, 2022
Author(s)
Catherine Cooksey, James A. Fedchak, Robert Hanisch, Gregory (Greg) C. Cala, Damian Lauria, Raymond Plante, Benjamin Long, John S. Quintavalle, Manmohan Moodra
Early in 2022 NIST embarked on a pilot project to produce digital calibration reports and certificates of analysis for reference materials. The goal of the project was to produce a few examples of each for the purpose of assessing the scope and challenges
Displaying 201 - 225 of 2714
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