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Search Publications by

Michael R Moldover (Assoc)

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Displaying 1 - 25 of 156


June 15, 2021
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
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 16, 2019
Jodie G. 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
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


April 18, 2019
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
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 17, 2018
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 17, 2018
Aaron N. Johnson, Iosif I. Shinder, Michael R. Moldover, Joey T. Boyd, Bernard J. 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 28, 2018
Jodie G. 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 21, 2018
John D. Wright, Aaron N. Johnson, Gina M. 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
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

Determination of the Boltzmann constant with cylindrical acoustic gas thermometry: new and final results

September 11, 2017
Keith A. Gillis, XiaoJuan Feng, Jintao Zhang, H. Lin, James B. Mehl, Michael R. Moldover, K Zhang, Y.N. Duan
We report a new determination of the Boltzmann constant kB using a cylindrical acoustic gas thermometer. We determined the length of the copper cavity from measurements of its microwave resonance frequencies. This contrasts with our previous work (Zhang et

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

September 11, 2017
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
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
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
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
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/f2 than by measuring the ratio p/T. Here f is the resonance

Advances in Thermometry

January 1, 2016
Michael R. Moldover, Weston L. Tew, Howard W. Yoon
The last 25 years have seen tremendous progress in thermometry in the moderate temperature range (1 K to 1235 K). Various primary thermometers — based on different physics —have uncovered errors in the International Temperature Scale of 1990 and set the


September 9, 2015
Michael R. Moldover, Roberto M. Gavioso, David B. Newell
We review correlated uncertainties among the accurate determinations of the Boltzmann constant kB that used the techniques of primary acoustic gas thermometry (AGT). We consider uncertainty contributions from four sources: (1) resonator-dependent

Test of a virtual cylindrical acoustic resonator for determining the Boltzmann constant

August 19, 2015
XiaoJuan Feng, Hong Lin, Keith A. Gillis, Michael R. Moldover, Jintao Zhang
We report progress in determining the Boltzmann constant kB using a virtual acoustic resonator derived by combining the measured frequencies of the longitudinal acoustic modes of two argon-filled, cylindrical, cavity resonators in such a way as to minimize