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Search Publications by: Michael R Moldover (Assoc)

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Displaying 151 - 175 of 321

Capacitors and Electromagnetic Resonators for Gas Metrology

May 1, 2007
Author(s)
Michael R. Moldover, James W. Schmidt
Gas-filled capacitors are being used as primary thermometers and they show promise as primary pressure standards and for measuring the Boltzmann constant. With these metrological applications in mind, we discuss the advantages and disadvantages of audio

Transport Properties of Argon at Zero Density From Viscosity-Ratio Measurements

April 1, 2006
Author(s)
E May, Michael R. Moldover, Robert F. Berg, John J. Hurly
We determined the zero-density viscosity and thermal conductivity of argon with an uncertainty of only 0.039 % in the temperature range 200 K to 400 K. Our results will improve: (1) the argon-argon interatomic potential, (2) calculated boundary-layer

Acoustic Thermometry: New Results From 273 K to 77 K and Progress Towards 4 K

January 1, 2006
Author(s)
Laurent Pitre, Michael R. Moldover, Weston L. Tew
We used a quasi-spherical cavity as an acoustic and microwave resonator to measure the thermodynamic temperatures T of the triple points of mercury, argon, neon, and equilibrium hydrogen, and to measure the difference T - T90, in the range 7 K to 273 K.

Relaxation Effects in Small Critical Nozzles

January 1, 2006
Author(s)
Aaron N. Johnson, C L. Merkle, Michael R. Moldover, John D. Wright
We computed the flow of four gases (He, N 2, CO 2, and SF 6) through a critical nozzle by augmenting traditional computational fluid dynamics (CFD) with a rate equation that accounts for τ relax, a species-dependent relaxation time that characterizes the

Bulk Viscosity of Stirred Xenon Near the Critical Point

November 1, 2005
Author(s)
Keith A. Gillis, Iosif I. Shinder, Michael R. Moldover
Following Gillis, Shinder, and Moldover [Phys. Rev. E 70, 021201 (2004)], we deduce the thermophysical properties of near-critical xenon from measurements of the frequencies and half-widths of the acoustic resonances of xenon maintained at its critical

Thermoacoustic Boundary Layers Near the Liquid-Vapor Critical Point

August 1, 2004
Author(s)
Keith A. Gillis, Iosif I. Shinder, Michael R. Moldover
We measure and calculate the sound attenuation within thermoacoustic boundary layers between solid surfaces and xenon at its critical density rc as the reduced temperature t=(T -Tc)/Tc approaches zero. (Tc is the critical temperature.) Using the singular

Gas Flowmeter Calibrations with the 34 L and 677 L PVTt Standards

June 23, 2004
Author(s)
John D. Wright, Aaron N. Johnson, Michael R. Moldover, Gina M. Kline
This document provides a description of the 34 L and 677 L pressure, volume, temperature, and time (PVTt) primary gas flow standards operated by the National Institute of Standards and Technology (NIST) Fluid Flow Group. These facilities are used to

Designing Quasi-Spherical Resonators for Acoustic Thermometry

June 1, 2004
Author(s)
J B. Mehl, Michael R. Moldover, J Pitre
We describe a quasi-spherical, noble-gas-filled cavity designed to determine the thermodynamic temperature of the gas from measurements of the frequencies and the half-widths of microwave and acoustic resonances in the cavity. The quasi-spherical shape
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