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: Keith A Gillis (Fed)

Search Title, Abstract, Conference, Citation, Keyword or Author
Displaying 26 - 50 of 91

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

August 19, 2015
Author(s)
XiaoJuan Feng, Hong Lin, Keith A. Gillis, Michael R. Moldover, Jintao Zhang
We report progress in determining the Boltzmann constant k B 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

Measuring collected gas with microwave and acoustic resonances

April 23, 2015
Author(s)
Keith A. Gillis, James W. Schmidt, Michael R. Moldover, James B. Mehl
With calibrations of large flow meters in mind, we established the feasibility of determining the mass M of argon gas contained within a 0.3 m 3 commercially manufactured pressure vessel ("tank") with a relative standard uncertainty of u r(M) = 0.0016 at 0

"Weighing" a Gas With Microwave and Acoustic Resonances

March 24, 2015
Author(s)
Keith A. Gillis, James B. Mehl, James W. Schmidt, Michael R. Moldover
With calibrations of large flow meters in mind, we established the feasibility of determining the mass Mof argon gas contained within a 0.3 m 3 commercially manufactured pressure vessel ("tank") with a relative uncertainty of u r(M) = 0.0015 at 0.6 MPa by

Microwave Determination of the Volume of a Pressure Vessel

December 9, 2014
Author(s)
Michael R. Moldover, James W. Schmidt, Keith A. Gillis, James B. Mehl, John D. Wright
Using microwave techniques that are scalable to very large volumes, we measured the interior volume of a 0.3 m 3, commercially-manufactured, pressure vessel with an uncertainty of 0.05 %, as confirmed by independent, more-accurate, gas-expansion

Acoustic Techniques for Measuring Transport Properties of Gases

May 22, 2014
Author(s)
Keith A. Gillis, Michael R. Moldover
We describe the principles, techniques, and performance of acoustic resonators used to measure the shear viscosity, the thermal conductivity, and the bulk viscosity in gases. We developed the Greenspan acoustic viscometer at NIST, where colleagues used it

Direct measurements of mass-specific optical cross sections of single component aerosol mixtures

July 22, 2013
Author(s)
James Radney, Xiaofei Ma, Keith A. Gillis, Michael R. Zachariah, Joseph T. Hodges, Christopher D. Zangmeister
The optical properties of atmospheric aerosols vary widely, being dependent upon particle composition, morphology and mixing state. This diversity and complexity of aerosols motivates measurement techniques that can discriminate and quantify a variety of

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

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