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Displaying 25151 - 25175 of 74219

Statistical analysis of fiber gripping effects on Kolsky bar test

June 14, 2011
Author(s)
Jae Hyun Kim, Nathanael A. Heckert, Stefan D. Leigh, Haruki Kobayashi, Walter G. McDonough, Richard L. Rhorer, Kirk D. Rice, Gale A. Holmes
Preliminary data for testing fibers at high strain rates using the Kolsky bar test by Ming Cheng et al. 1 indicated minimal effect of strain rate on the tensile stress-strain behavior of PPTA, poly (p-phenylene terephathalamide) fibers. In a different

Cryocoolers for Aircraft Superconducting Generators and Motors

June 13, 2011
Author(s)
Ray Radebaugh
The proposal by NASA to use high temperature superconducting (HTS) generators and motors on future (2035) aircraft for turboelectric propulsion imposes difficult requirements for cryocoolers. Net refrigeration powers of about 5 kW to 10 kW at 50 K to 65 K

Division Polynomials for Jacobi Quartic Curves

June 13, 2011
Author(s)
Dustin Moody
In this paper we fi nd division polynomials for Jacobi quartics. These curves are an alternate model for elliptic curves to the more common Weierstrass equation. Division polynomials for Weierstrass curves are well known, and the division polynomials we fi

Experiments with Linear Compressors for Phase Shifting in Pulse Tube Cryocoolers

June 13, 2011
Author(s)
Michael A. Lewis, Peter E. Bradley, Ray Radebaugh
For the past year NIST has been investigating the use of mechanical phase shifters as warm expanders for pulse tube cryocoolers. Unlike inertance tubes, which have a limited phase shifting ability at low acoustic powers, mechanical phase shifters have the

Radio Frequency Measurements to Support Public Safety Wireless Communications in Large Buildings and Structures

June 13, 2011
Author(s)
William F. Young, Catherine A. Remley, Christopher L. Holloway, Galen H. Koepke, Dennis G. Camell, John M. Ladbury
The public safety community requires dependable wireless communications in buildings that often disrupt the radio frequency propagation due to the construction material, architectural features, or large physical dimensions. Here we introduce measurements

Development of a multifilament PIT V3Ga conductor for fusion applications

June 12, 2011
Author(s)
Najib Cheggour, Theodore C. Stauffer, Loren F. Goodrich, L. R. Motowidlo, J Distin, P. J. Lee, David C. Larbalestier, A. K. Ghosh
Previous studies on V3Ga assert its suitability for use in proposed fusion reactors. V3Ga may outperform Nb3Sn in a fusion reactor environment based on its relatively flat critical-current profile in the 15 T- 20 T range, resilience to applied strain, and

Measuring the Impact of Engineering Research Publications

June 12, 2011
Author(s)
Stacy M. Bruss, Susan L. Makar
The Information Services Office (ISO) of the National Institute of Standards and Technology (NIST) recently conducted a study to assess the publishing impacts for a group of engineering researchers. While the original request focused on calculating the h

Trophic Magnification Factors: Impact of Ecology, Ecosystem and Study Design

June 11, 2011
Author(s)
Katrine Borga, Karen Kidd, Olof Berglund, Jason Conder, Frank Gobas, John Kucklick, Olaf Malm, Dave Powell, Derek Muir
Recent reviews by researchers from academia, industry and government have revealed that the criteria used by the Stockholm Convention on persistent organic pollutants (POPs) under the United Nations Environmental Programme are unable to identify the actual

Examination of United States Carbon Dioxide Emission Databases

June 10, 2011
Author(s)
Robert P. Borthwick, James Whetstone, Jiann C. Yang, Antonio Possolo
This paper compared carbon dioxide emissions from plants obtained in two ways, first from the US Department of Energy, Energy Information Administration EIA-767 database and EIA-1605 Greenhouse Gas Reporting Program guidelines and second from the U.S. Envi

Proposed UNIFORMAT II Classification of Bridge Elements

June 10, 2011
Author(s)
Muthiah Kasi, Robert E. Chapman
This report presents a proposed UNIFORMAT II classification of bridge elements. Elemental classifications differ from traditional product-related classifications because their core concept is an element that performs a given function, regardless of the

Report of the 95th National Conference on Weights and Measures

June 10, 2011
Author(s)
Linda D. Crown, Tina G. Butcher, Steven E. Cook, Lisa Warfield, David A. Sefcik
The 95th Annual Meeting of the National Conference on Weights and Measures (NCWM) was held July 11 to 15, 2010, at the Crowne Plaza St. Paul Riverfront, St. Paul, Minnesota. The theme of the meeting was “Breaking Molds to Shape the Future.” Reports by the

Controlled Vapor Deposition Approach to Generating Surface Energy/Chemistry Gradients

June 9, 2011
Author(s)
Julie N. Albert, Joey D. Kim, Christopher Stafford, Thomas H. Epps
Substrate surface energy/chemistry gradients provide a means for high-throughput exploration of the surface interactions that are important for many chemical and biological processes. We describe the implementation of a controlled vapor deposition approach

Dzyaloshinskii-Moriya Interaction and Spin Re-Orientation Transition in the Frustrated Kagome Lattice Antiferromagnet

June 9, 2011
Author(s)
K. Matan, B. M. Bartlett, Joel Helton, V. Sikolenko, S. Mat'as, K. Prokes, Ying Chen, Jeffrey W. Lynn, D. Grohol, T. J. Sato, M. Tokunaga, D. G. Nocera, Y. S. Lee
Magnetization, specific heat, and neutron scattering measurements were performed to study a magnetic transition in jarosite, a spin-5/2} kagome lattice antiferromagnet. When a magnetic field is applied perpendicular to the kagome plane, magnetizations in

Strongly quadrature-dependent noise in superconducting microresonators measured at the vacuum-noise limit

June 9, 2011
Author(s)
Jiansong Gao, Kent D. Irwin, Gene C. Hilton, John A. Mates, Daniel R. Schmidt, Leila R. Vale, Konrad W. Lehnert, Francois Mallet, Jonas Zmuidzinas
We report noise measurement of superconducting micro-resonators with a Josephson parametric amplifier. These resonators show significant amount of frequency noise caused by surface two-level systems. However, in the dissipation quadrature, no excess noise

Successful Design of Biometric Tests in a Constrained Environment

June 9, 2011
Author(s)
Vladimir N. Dvornychenko
The National Institute of Standards and Technology (NIST), with participation of the biometrics community, conducts evaluations of biometrics-based verification and identification systems. Among the more challenging is testing of automated latent

Thin Film Dynamics on a Prolate Ellipsoid with Application to the Cornea

June 9, 2011
Author(s)
Richard J. Braun, R. Usha, Geoffrey B. McFadden, T. A. Driscoll, L. P. Cook, P. E. King-Smith
We study the flow of a thin fluid film on a prolate ellipsoid that is a good approximation to the shape of the human cornea. Two lubrication models for the dynamics of the film are studied in prolate spheroidal coordinates which are appropriate for this
Displaying 25151 - 25175 of 74219
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