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Search Publications by: Michael R Moldover (Assoc)

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Displaying 76 - 100 of 321

Viscosity-ratio measurements with capillary viscometers

May 20, 2014
Author(s)
Robert F. Berg, Eric F. May, Michael R. Moldover
Viscosity-ratio measurements made with capillary viscometers exploit the accurate values of the viscosity of helium resulting from ab initio calculations. Accurate values of the argon-to-helium viscosity ratio are now used for primary acoustic thermometry

Acoustic Gas Thermometry

January 16, 2014
Author(s)
Michael R. Moldover, Roberto M. Gavioso, James B. Mehl, Laurent Pitre, Michael de Podesta, Jintao Zhang
Primary acoustic gas thermometry (AGT) exploits the simple relationship between the speed of sound in a dilute gas u and the thermodynamic temperature T of the gas. For monatomic gases such as argon and helium, u2 = (5/3) kT/m, in the limit of zero

ACOUSTIC GAS THERMOMETRY

January 16, 2014
Author(s)
Michael R. Moldover, Roberto M. Gavioso, James B. Mehl, Laurent Pitre, Michael de Podesta, Jintao Zhang
We review the principles, techniques and results from primary acoustic gas thermometry (AGT). Since the establishment of ITS-90, the International Temperature Scale of 1990, spherical and quasi-spherical cavity resonators have been used to realize primary

Viscosity-ratio measurements with capillary viscometers

November 27, 2013
Author(s)
Robert F. Berg, Eric F. May, Michael R. Moldover
Viscosity-ratio measurements made with capillary viscometers exploit the accurate values of the viscosity of helium calculated ab initio. Accurate values of the argon-to-helium viscosity ratio are now used for primary acoustic gas thermometry and for the

IMPROVEMENTS TO NIST'S AIR SPEED CALIBRATION SERVICE

September 24, 2013
Author(s)
Iosif I. Shinder, Christopher J. Crowley, Bernard J. Filla, Michael R. Moldover
We discuss five significant improvements to the Air Speed Calibration Service conducted by the National Institute of Standards and Technology (NIST): 1. Reduced-uncertainty calibrations of the secondary standard [Laser Doppler Anemometer, (LDA)] using a

The Effect of Turbulence on a Multi-Hole Pitot Calibration

June 10, 2013
Author(s)
Christopher J. Crowley, Iosif I. Shinder, Michael R. Moldover
Abstract- Accurate calibrations of multi-hole Pitot tubes require thousands of measurements spanning ranges of the fluid’s velocity, and the pitch and yaw angles. When calibrating a commercially-manufactured multi-hole Pitot tube in NIST’s low-turbulence

Microwave measurements for gas thermometry up to the copper point

May 13, 2013
Author(s)
XiaoJuan Feng, Keith A. Gillis, Michael R. Moldover, James B. Mehl
We measured 5 microwave resonance frequencies f N of an argon-filled cylindrical cavity at temperatures up to 1349 K. The repeatability of both the measured frequencies u(f N) and the scaled half-widths u(g N)/ f N was better than 10 -6f N. The measurement

Recommended viscosities of 11 dilute gases at 25?degC

December 13, 2012
Author(s)
Robert F. Berg, Michael R. Moldover
Commercially manufactured meters that measure the flow of a process gas are often calibrated with a known flow of a surrogate gas. This requires an accurate model of the flow meter and accurate values of the relevant thermophysical properties for both

Room Temperature Acoustic Transducers for High-Temperature Thermometry

July 9, 2012
Author(s)
Dean C. Ripple, William E. Murdock, Gregory F. Strouse, Keith A. Gillis, Michael R. Moldover
We have successfully conducted highly-accurate, primary acoustic thermometry at 600 K using a sound source and a sound detector at room temperature. We describe the source, the detector, and the ducts that connected them to our cavity resonator. This

TESTING LONG-WAVELENGTH ACOUSTIC FLOWMETER CONCEPTS FOR FLUE GAS FLOWS

June 22, 2012
Author(s)
Lee J. Gorny, Keith A. Gillis, Michael R. Moldover
As a part of NIST’s program to standardize measurements of greenhouse gas emissions, we are developing a long-wavelength acoustic flowmeter (LWAF) for accurate, economical measurements of exhaust flows from coal-burning power plants. Measurements of the

Airspeed Calibration Services: Laser Doppler Anemometer Calibration and Its Uncertainty

June 20, 2012
Author(s)
Iosif I. Shinder, Michael R. Moldover, J. M. Hall, Mike Duncan, Joe Keck
The National Institute of Standards and Technology (NIST) and the Oak Ridge National Laboratory (ORNL) are improving their airspeed calibration services. Both laboratories use spinning disks to generate linear velocities that are traceable to NIST’s length