U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Search Publications by: Michael R Moldover (Assoc)

Search Title, Abstract, Conference, Citation, Keyword or Author
Displaying 1 - 25 of 161

Ab initio Calculation of Fluid Properties for Precision Metrology

September 12, 2023
Author(s)
Giovanni Garberoglio, Christof Gaiser, Roberto Maria Gavioso, Allan H. Harvey, Robert Hellmann, Bogumil Jeziorski, Karsten Meier, Michael R. Moldover, Laurent Pitre, Krzysztof Szalewicz, Robin Underwood
Recent advances regarding the interplay between ab initio calculations and metrology are reviewed, with particular emphasis on gas-based techniques used for temperature and pressure measurements. Since roughly 2010, several thermophysical quantities – in

Non-nulling Protocols for Fast, Accurate, 3-D Velocity Measurements in Stacks

July 28, 2023
Author(s)
Iosif Isaakovich Shinder, Aaron Johnson, James Filla, Vladimir B. Khromchenko, Michael R. Moldover, Joey Boyd, John D. Wright, John R. Stoup
We present protocols for making fast, accurate, 3-D velocity measurements in the stacks of coal-fired power plants. The measurements are traceable to internationally-recognized standards; therefore, they provide a rigorous basis for measuring and/or

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

Facility for calibrating anemometers as a function of air velocity vector and turbulence

July 19, 2021
Author(s)
Iosif Isaakovich Shinder, Michael R. Moldover, James Filla, Aaron Johnson, Vladimir B. Khromchenko
NIST calibrates anemometers as a function of airspeed vector and turbulence intensity (Tu). The vector capability (sometimes called '3D') is particularly important for calibrating multi-hole differential-pressure probes that are often used to quantify

Acoustic measurement of the triple point of neon TNe and thermodynamic calibration of a transfer standard for accurate cryogenic thermometry

July 9, 2021
Author(s)
Changzhao Pan, Fernando Sparasci, Haiyang Zhang, Pascal Gambette, Mark Plimmer, Dario Imbraguglio, Roberto M. Gavioso, Michael R. Moldover, Bo Gao, Laurent Pitre
We used absolute primary acoustic gas thermometry (AGT) to calibrate a Pt-Co resistance thermometer on the thermodynamic temperature scale by measuring the speed of sound in helium at a temperature T* chosen to be near the temperature of the triple point

LIQUID FLOW METER CALIBRATIONS WITH NIST's 15 kg/s WATER FLOW STANDARD

June 15, 2021
Author(s)
Jodie Gail Pope, Aaron Johnson, James Filla, Vern E. Bean, Michael R. Moldover, Joey Boyd, Christopher J. Crowley, Iosif Isaakovich Shinder, Keith A. Gillis, John D. Wright
We describe the 15 kg/s water flow calibration standard operated by the Fluid Metrology Group of the National Institute of Standards and Technology (NIST) to calibrate liquid flow meters for customers. The 15 kg/s standard is a dynamic, gravimetric, liquid

Faster, More Accurate, Stack-Flow Measurements

February 25, 2020
Author(s)
Aaron N. Johnson, Iosif I. Shinder, Bernard J. Filla, Joey T. Boyd, Rodney A. Bryant, Michael R. Moldover, Thomaa D. Martz, Matthew Gentry
Exhaust flows from coal-fired electricity-generating-plants are determined by measuring the flue gas velocity at prescribed points in the stack cross section. These velocity measurements are made using EPA-approved differential pressure probes such as the

Progress Towards a Gas-Flow Standard using Microwave and Acoustic Resonances

July 15, 2019
Author(s)
Jodie Gail Pope, Keith A. Gillis, Michael R. Moldover, Eric Harman, James Mehl
We describe our progress in the development of a novel gas flow standard using the acoustic and microwave resonances of a 1.85 m3, nearly-spherical, steel vessel at pressures up to 7 MPa. For flow calibrations using pressure and acoustic frequency

Non Nulling Measurements of Flue Gas Flows in a Coal-Fired Power Plant Stack

June 28, 2019
Author(s)
Aaron N. Johnson, Iosif I. Shinder, Bernard J. Filla, Joey T. Boyd, Rodney A. Bryant, Michael R. Moldover
Exhaust flows from coal-fired stacks are determined by measuring the flue gas velocity at prescribed points in the stack cross section. During the last 30+ years these velocity measurements have been made predominantly using S-type pitot probes. These

REFRACTIVE-INDEX GAS THERMOMETRY

April 18, 2019
Author(s)
Patrick Rourke, Christof Gaiser, Roberto M. Gavioso, Michael R. Moldover, Laurent Pitre, Robin Underwood
The principles and techniques of primary refractive-index gas thermometry (RIGT) are reviewed. Absolute primary RIGT using microwave measurements of helium-filled quasi-spherical resonators has been implemented at the temperatures of the triple points of

Improving Measurement for Smokestack Emissions - Workshop Summary

September 21, 2018
Author(s)
Rodney A. Bryant, Aaron N. Johnson, John D. Wright, Tamae M. Wong, James R. Whetstone, Michael R. Moldover, Iosif I. Shinder, Scott Swiggard, Chris Gunning, David Elam, Tom Martz, Eric Harman, David Nuckols, Liang Zhang, Woong Kang, Salvator Vigil
The complex flow conditions inherent in power plant smokestacks make accurate flow measurements challenging, which in turn limits the accuracy of hazardous emissions measurements. While stack composition measurements are assessed daily via comparison to a

Characterization of Five-Hole Probes used for Flow Measurement in Stack Emission Testing

May 16, 2018
Author(s)
Iosif Isaakovich Shinder, Aaron Johnson, Michael R. Moldover, James Filla, Vladimir Khromchenko
We report progress towards the goal of reducing the errors in industrial smokestack flow measurements to 1 % by replacing S-probes with calibrated 3-D probes (i.e., probes that measure 3 components of velocity). NIST calibrated a commercially-manufactured

Progress Towards Accurate Monitoring of Flue Gas Emissions

May 16, 2018
Author(s)
Aaron Johnson, Iosif Isaakovich Shinder, Michael R. Moldover, Joey Boyd, James Filla
The amounts of CO2 and other pollutants emitted by a coal-fired power plant are measured using a continuous emissions monitoring system (CEMS) permanently installed in the exhaust smokestack. The pollutant flux is the product of the pollutant's

Characterizing Gas-Collection Volumes with Acoustic and Microwave Resonances

March 27, 2018
Author(s)
Jodie Gail Pope, Keith A. Gillis, Michael R. Moldover, J B. Mehl, Eric Harman
We characterized a 1.8 m3, nearly-spherical, steel shell at pressures up to 7 MPa for use as a gas flow standard. For pressure, volume, temperature, and time measurements, the shell's cavity will collect gas; for blow-down measurements, the shell will be a

Errors in Rate of Rise Gas Flow Measurements from Flow Work

March 20, 2018
Author(s)
John D. Wright, Aaron Johnson, Gina Kline, Michael R. Moldover
The rate of rise (RoR) method measures the time rate of change of the mass of gas in a collection volume as it is filled via a flow meter under test. The mass of gas is calculated from time-stamped pressure and temperature data gathered from the known

The Boltzmann Project

February 5, 2018
Author(s)
Samuel P. Benz, Joachim Fischer, Bernd Fellmuth, Christof Gaiser, Laurent Pitre, Fernando Sparasci, Lara Risegari, Roberto M. Gavioso, D M. Rippa, Bengt Hallstedt, Jifeng Qu, XiaoJuan Feng, Jianqiang Zhang, David R. White, L Gianfrani, A Castrillo, L Moretti, B Darquie, C Daussy, S Briaudeau, O Kozlova, J J. Segovia, M C. Martin, D del Campo, Michael R. Moldover
The International Committee for Weights and Measures (CIPM), at its meeting in October 2017 followed the recommendation of the Consultative Committee for Units (CCU) on the redefinition of the kilogram, ampere, kelvin and mole. For the redefinition of the

New measurement of the Boltzmann constant k by acoustic thermometry of helium-4 gas

September 11, 2017
Author(s)
Laurent Pitre, Fernando Sparasci, Michael R. Moldover, Cecile Guianvarch, Catherine Martin, Martin Himbert, Mark Plimmer, James B. Mehl, Giuliano Albo, Bo Gao, Lara Risegari
The SI unit of temperature will soon be redefined in terms of a fixed value of the Boltzmann constant k derived from an ensemble of measurements worldwide. We report on a new determination of k using acoustic thermometry of helium-4 gas in a 3-litre quasi

Determination of the molar mass of argon from a high precision acoustic comparison

May 18, 2017
Author(s)
XiaoJuan Feng, Jintao Zhang, Michael R. Moldover, Inseok Yang, Mark Plimmer, H. Lin
This article describes the accurate determination of the molar mass of a sample of argon gas used for a determination of the Boltzmann constant. The method due to one of the authors [Moldover et al., J. Res. Natl. Bur. Stand. 93, 85-144 (1988)] uses the

Energy accommodation coefficient extracted from acoustic resonator experiments

November 2, 2016
Author(s)
Felix Sharipov, Michael R. Moldover
We review values of the temperature jump coefficient zeta_T determined from measurements of the acoustic resonance frequencies f_acoust of helium-filled and argon-filled, metal-walled, quasi- spherical cavities near ambient temperature. We combine these

NIST Programs to Advance Accurate, Internationally-Recognized Stack Emissions Measurements

September 15, 2016
Author(s)
Aaron Johnson, Iosif Isaakovich Shinder, Rodney A. Bryant, JohnPaul R. Abbott, Keith A. Gillis, Joey Boyd, James Filla, Michael R. Moldover
Accurate flow measurements are essential to quantify the amount of greenhouse gases (GHGs) and other pollutants emitted from power plant stacks. Although protocols have been developed, the uncertainty of stack flow measurements has not been documented. 

Detecting leaks in gas-filled pressure vessels using acoustic resonances

May 6, 2016
Author(s)
Keith A. Gillis, Michael R. Moldover, James B. Mehl
We demonstrate that a leak from a large, unthermostatted pressure vessel into ambient air can be detected an order of magnitude more effectively by measuring the time dependence of the ratio p/f 2 than by measuring the ratio p/T. Here f is the resonance