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1. "Weighing" a Gas With Microwave and Acoustic Resonances
Published: 3/24/2015
Authors: Keith A Gillis, James B. Mehl, James W Schmidt, Michael R Moldover
Abstract: With calibrations of large flow meters in mind, we established the feasibility of determining the mass {I}M{/I}of argon gas contained within a 0.3 m^u3^ commercially manufactured pressure vessel ("tank") with a relative uncertainty of {I}u{/I}^dr^({I ...

2. Microwave Determination of the Volume of a Pressure Vessel
Published: 12/9/2014
Authors: Michael R Moldover, James W Schmidt, Keith A Gillis, James B. Mehl, John D Wright
Abstract: Using microwave techniques that are scalable to very large volumes, we measured the interior volume of a 0.3 m^u3^, commercially-manufactured, pressure vessel with an uncertainty of 0.05 %, as confirmed by independent, more-accurate, gas-expansion me ...

3. Reference measurements of Hydrogen's Dielectric Permittivity
Published: 8/10/2009
Authors: James W Schmidt, Michael R Moldover, Eric F. May
Abstract: We used a quasi-spherical cavity resonator to measure the relative dielectric permittivity {epsilon}^dr^ of H^d2^ 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 calibrat ...

4. The Electric And Magnetic Susceptibilities Of Gaseos Oxygen: Comparisons Of New Measurements and Modern Theory
Published: 9/25/2008
Authors: Michael R Moldover, E May, James W Schmidt
Abstract: We used a cross capacitor to measure the relative dielectric permittivity {epsilon}^dr^ of O^d2^ at 273 K, 293 K, and 323 K and at pressures up to 6.5 MPa. Simultaneously we measured oxygen's complex refractive index {I}n{/I} using a quasi-spheri ...

5. The Polarizability of Helium and Gas Metrology
Published: 6/22/2007
Authors: James W Schmidt, R Gavioso, E May, Michael R Moldover
Abstract: Using a quasi-spherical, microwave cavity resonator, we measured the refractive index of helium to deduce its molar polarizability {I}A{/I}^d{epsilon}^ in the limit of zero density. We obtained ({I}A{/I}^d{epsilon},meas^ - {I}A{/I}^d{epsilon},theory^ ...

6. Capacitors and Electromagnetic Resonators for Gas Metrology
Published: 5/1/2007
Authors: Michael R Moldover, James W Schmidt
Abstract: 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 a ...

7. Primary Pressure Standards Based on Dimensionally Characterized Piston/Cylinder Assemblies
Published: 2/1/2006
Authors: James W Schmidt, K. Jain, A P. Miiller, Walter J. Bowers Jr., Douglas A Olson
Abstract: NIST has characterized two large diameter (35.8 mm) piston/cylinder assemblies as primary pressure standards in the range from 0.05 to 1.0 MPa with uncertainties approaching the best mercury manometers. The realizations of the artifacts as primary st ...

8. The Dielectric Permittivity of Saturated Liquid Carbon Dioxide and Propane Measured Using Cross Capacitors
Published: 5/1/2005
Authors: E May, Michael R Moldover, James W Schmidt
Abstract: The relative dielectric permittivities er of saturated liquid carbon dioxide (CO2) and propane (C3H8) were measured using well-characterized cross capacitors in the range 260 K < T < 300 K. We calculated the molar polarizability sat (er -1)/[(er ...

9. Quasi-Spherical Cavity Resonators for Metrology Based on the Relative Dielectric Permittivity of Gases
Published: 10/1/2004
Authors: E May, Laurent Pitre, J B. Mehl, Michael R Moldover, James W Schmidt
Abstract: We evaluate a quasi-spherical, copper, microwave cavity resonator for accurately measuring the relative dielectric permittivity {epsilon^dr^(p,T)} of helium and argon. In a simple, crude approximation the cavity s shape is a triaxial ellipsoid with a ...

10. A Primary Dead-Weight Tester for Pressures (0.05-1.0) MPa
Series: Journal of Research (NIST JRES)
Published: 4/1/2003
Authors: K. Jain, Walter J. Bowers Jr., James W Schmidt
Abstract: Recent advances in technology on two fronts, 1) the fabrication of large diameter pistons and cylinders with good geometry, and 2) the ability to measure the dimensions of these components with high accuracy, have allowed dead-weight testers at NIST ...

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