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Search Publications by: Michael R Moldover ()

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Displaying 26 - 50 of 321

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

Advances in Thermometry

January 1, 2016
Author(s)
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