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Displaying 176 - 200 of 275

Power Loading Effects in Precision 1 Ohm Resistors

August 1, 2008
Author(s)
George R. Jones, Randolph E. Elmquist
Five manganin alloy Thomas-type 1 Ohm resistors serve as primary working standards at the National Institute of Standards and Technology (NIST) in the precision potentiometer direct current comparator (DCC) system used for special 1 Ohm customer

CHARACTERIZATION OF LOADING EFFECTS IN PRECISION 1 Ohm RESISTORS

June 1, 2008
Author(s)
George R. Jones Jr., Randolph Elmquist
Precision standard resistors manufactured within the last two decades using improved construction techniques and materials, such as the resistance alloy Evanohm, have been shown to have excellent environmental characteristics. Power dissipation (or loading

HIGH RESISTANCE SCALING FROM 10 k(OHM) AND QHR STANDARDS USING A CRYOGENIC CURRENT COMPARATOR

June 1, 2008
Author(s)
Randolph Elmquist, George R. Jones Jr., Brian J. Pritchard, Marcos E. Bierzychudek, Felipe L. Hernandez
We describe a cryogenic current comparator (CCC) bridge for resistance scaling that provides improved measurement uncertainty over a range of resistance values from 100 k(Ω) to 1 G(Ω). This CCC is designed for high resistance scaling based directly on a

SIM COMPARISON OF DC RESISTANCE AT 1 Ohm, 1 MOhm, AND 1 GOhm

June 1, 2008
Author(s)
Dean G. Jarrett, Randolph Elmquist, Nien F. Zhang, Alejandra Tonina, Janice Fernandes, Daniel Izquierdo, Dave Inglis, Felipe Hernandez-Marquez
A regional comparison of DC resistance standards at the nominal values of 1 Ohm, 1 MOhm, and 1 GOhm has recently been completed in the System Interamericano de Metrogia (SIM) region. The motivation, design, standards, and results of this regional

UNCERTAINTY EVALUATION IN A TWO-TERMINAL CRYOGENIC CURRENT COMPARATOR

June 1, 2008
Author(s)
Marcos E. Bierzychudek, Randolph Elmquist
In this paper we present the uncertainty evaluation of a new cryogenic current comparator (CCC) bridge designed to compare two-terminal 1M Ω} and 10M Ω} standard resistors with the quantized Hall resistance (QHR) and then scale from these values to other

The NIST Calibration Check Standards Database

June 1, 2007
Author(s)
Kevin G. Brady, Frederic J. de Vaulx, Randolph Elmquist
For several years now, NIST has been a leader in the development and use of Information Technology to process calibration information. Beginning in 1996, researchers designed and developed a calibration database, the NIST Information System to Support

Temperature and Pressure Coefficients of Thomas 1 Ohm Resistors

August 1, 2006
Author(s)
George R. Jones Jr., Randolph Elmquist
In preparing to move the precision 1 ohm measurement service to the new Advanced Measurement Laboratory (AML) in the spring of 2004, staff at the National Institute of Standards and Technology (NIST) first assembled a second precision 1 ohm measurement

Settling Times of High-Value Standard Resistors

June 1, 2004
Author(s)
Dean G. Jarrett, Randolph Elmquist
An investigation of the response of high-value resistance standards and elements to applied potential has showed that the processes used to prepare and construct high-value resistance standards can effect the settling times of these standards. Improvements

Tech Note 1458|NIST Measurement Service for DC Standard Resistors

March 8, 2004
Author(s)
Randolph Elmquist, Dean G. Jarrett, George R. Jones Jr., Marlin E. Kraft, Scott H. Shields, Ronald F. Dziuba
At the National Institute of Standards and Technology (NIST), the U.S. representation of the ohm is based on the quantum Hall effect, and it is maintained and disseminated at various resistance levels by working reference groups of standards. This document