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Displaying 76 - 100 of 2600

New Method for Determining Time Constant of Resistors

March 21, 2023
Yicheng Wang, Dean G. Jarrett, Andrew D. Koffman, Stephan Schlamminger
We report a new method for determining the time constant of ac resistors with values around 10 kΩ, using a digital impedance bridge for comparison of two nominally equal resistors. The method involves adding a probing capacitor in parallel to one of the

Resolving Complex Photoconductivity of Perovskite and Organic Semiconductor Films Using Phase-Sensitive Microwave Interferometry

March 2, 2023
Jasleen Bindra, Pragya Shrestha, Sebastian Engmann, Chad Cruz, Lea Nienhaus, Emily Bittle, Jason Campbell
Complex transient photoconductivity (Δσ) contains rich fingerprints of charge recombination dynamics in photoactive films. However, a direct measure of both real (Δσ′) and imaginary (Δσ″) components has proven difficult using conventional cavity-based time

Preparation and Standardization of 229Th SRM 4328d

February 24, 2023
Ronald Colle, Lizbeth Laureano-Perez, Morgan DiGiorgio
The certified massic activity for 229Th in SRM 4328d was obtained by 4παβ liquid scintillation (LS) counting by comparative measurements in 2022 against SRM 4328c. Both SRMs were prepared from the identical 2007 229Th stock solution. SRM 4328c was

Checking the Net Contents of Packaged Goods

February 13, 2023
Tina G. Butcher, David Sefcik, Lisa Warfield, Elizabeth Benham, Shelby Bowers, Katrice Lippa
This handbook has been prepared as a procedural guide for the compliance testing of net content statements on packaged goods. Compliance testing of packaged goods is the determination of the conformance results of packaging, distribution, and sale of

Uniform Laws and Regulations in the Areas of Legal Metrology and Fuel Quality

February 13, 2023
Tina G. Butcher, David Sefcik, Lisa Warfield, Shelby Bowers, Katrice Lippa
NIST Handbook 130 includes a compilation of model laws and regulations and related interpretations and guidelines designed to encourage uniformity in adoption and implementation of weights and measures laws and regulations. The model laws and regulations

A Non-Intrusive Fluorescent Pattern for Internal Microscale Strain Measurements Using Digital Image Correlation

February 1, 2023
Ami Ahure Powell, William Mulhearn, Shawn Chen, Stephan J. Stranick, Jeffrey Gilman, Mark Iadicola, Jeremiah Woodcock
A non-intrusive and non-disruptive internal fluorescent pattern is designed, developed, and tested using digital image correlation (DIC), an effective non-contact optical method, to measure deformation at internal planes of a polymer matrix material. The

Specifications, Tolerances, and Other Technical Requirements for Weighing and Measuring Devices

January 30, 2023
Tina G. Butcher, Richard A. Harshman, Jan Konijnenburg, Gloria Diane Lee, Juana Williams, Lisa Warfield, Shelby Bowers, Katrice Lippa, 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
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
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
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
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
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
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

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

December 12, 2022
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
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
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

Calculation of magnetic forces and torques on the Kibble coil

October 22, 2022
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
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)
Displaying 76 - 100 of 2600