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: Michael R Moldover (Assoc)

Search Title, Abstract, Conference, Citation, Keyword or Author
Displaying 126 - 150 of 321

Improved NIST Airspeed Calibration Facility

March 23, 2010
Author(s)
Iosif I. Shinder, J. M. Hall, Michael R. Moldover
The National Institute of Standards and Technology (NIST) uses a laser Doppler anemometer (LDA) as a working standard for airspeed calibrations in the range 0.15 m/s to 75 m/s (0.34 to 168 miles/hour). We report improved procedures for calibrating the LDA

Optimizing Acoustic Measurements of the Boltzmann Constant

November 22, 2009
Author(s)
Michael R. Moldover
We review the progress in acoustic metrology of gases that has occurred since the 1988 measurement of the universal gas constant R using a spherical acoustic resonator. The advances in understanding resonators and in calculating the thermophysical

Perturbations from Ducts on the Modes of Acoustic Thermometers

September 1, 2009
Author(s)
Keith A. Gillis, Michael R. Moldover, Hong Lin
We examine the perturbations of the modes of an acoustic thermometer caused by circular ducts used either for gas flow or as acoustic waveguides coupled to remote transducers. We calculate the acoustic admittance of circular ducts using a model based on

Dynamic Gravitational Standard for Liquid Flow: Model and Measurements

August 14, 2009
Author(s)
Iosif I. Shinder, Michael R. Moldover
We report progress in testing a dynamic gravimetric standard using both steady and unsteady water flows. For steady flows in the range 10 kg/s to 60 kg/s, the difference between the dynamic standard and NIST s static primary standard was 0.015 % with a

Reference measurements of Hydrogen's Dielectric Permittivity

August 10, 2009
Author(s)
James W. Schmidt, Michael R. Moldover, Eric F. May
We used a quasi-spherical cavity resonator to measure the relative dielectric permittivity ε r of H 2 at frequencies from 2.4 GHz to 7.3 GHz, at pressures up to 6.5 MPa, and at the temperatures 273 K and 293 K. The resonator was calibrated using auxiliary

High Definition Flow

August 1, 2009
Author(s)
John D. Wright, Michael R. Moldover
From pharmaceutical production to the natural gas market, exact flow measurements are critical. Here's how NIST helps keep us all on the same page.

Accurately Measuring Unsteady Water Flows Using A Dynamic Standard

April 1, 2009
Author(s)
Iosif I. Shinder, Michael R. Moldover
We recently presented and tested a model for a dynamic gravimetric standard for steady water flows. In the range 10 kg/s to 60 kg/s, the difference between the dynamic standard and NIST's static primary standard was 0.015 % with a standard deviation of 0

Shear Thinning Near the Critical Point of Xenon

April 17, 2008
Author(s)
Robert F. Berg, Michael R. Moldover, M Yao, G A. Zimmerli
We measured shear thinning, a viscosity decrease ordinarily associated with complex liquids, near the critical point of xenon. The data span the range of reduced shear rates: 0.001 < γτ < 700, where γτ is the shear rate scaled by the relaxation time τ of

Acoustic Thermometry Results From 271 K to 552 K

September 8, 2007
Author(s)
Dean C. Ripple, Gregory F. Strouse, Michael R. Moldover
The NIST Acoustic Thermometer determines the thermodynamic temperature from measurements of ratios of the speed of sound of argon in a spherical cavity. We report recent results for T - T90 on 12 isotherms spanning the range 271 K to 552 K. (T is the

Reference Viscosities of H 2 , CH 4 , Ar and Xe at Low Densities

August 1, 2007
Author(s)
E May, Robert F. Berg, Michael R. Moldover
We determined the zero-density viscosity eta of hydrogen, methane and argon in the temperature range 200 K to 400 K, with standard uncertainties of 0.084 % for hydrogen and argon and 0.096 % for methane. These uncertainties are dominated by the uncertainty

The Polarizability of Helium and Gas Metrology

June 22, 2007
Author(s)
James W. Schmidt, R Gavioso, E May, Michael R. Moldover
Using a quasi-spherical, microwave cavity resonator, we measured the refractive index of helium to deduce its molar polarizability A ε in the limit of zero density. We obtained (A ε,meas - A ε,theory)/A ε = (-1.8plus or minus} 8.4)× 10 -6, where the

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
Was this page helpful?