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Displaying 36526 - 36550 of 74855

In-Cavity Calibration of High Heat-Flux Sensors: Experimental Validation

June 9, 2005
Author(s)
A V. Murthy, Gerald T. Fraser, D P. DeWitt
This paper deals with the feasibility of performing primary calibration of heat-flux sensors at high irradiance levels by placing inside the cylindrical cavity of a graphite-tube blackbody. The experimental study comprised of measurements on two Schmidt

Details of the Sequential Steps in Magnetocaloric Regeneration

June 8, 2005
Author(s)
F Shir, Lawrence H. Bennett, Edward Della Torre, C Mavriplis, L Yanik, Robert D. Shull
We report on the first demonstration of the four sequential steps in magnetocaloric regeneration of a magnetocaloric material: magnetization, warm blow, demagnetization, and cold blow. The experimental results display temperature divergence due to

Microfabricated atomic frequency references

June 7, 2005
Author(s)
John E. Kitching, Svenja A. Knappe, Li-Anne Liew, John Moreland, P Schwindt, V Shah, Vladislav Gerginov, Leo W. Hollberg
Using microfabrication processes, we have been able to construct physics packages for vapour cell atomic frequency references 100¿ smaller than previously existing versions, with a corresponding reduction in power consumption. In addition, the devices

Nanometer Gaps in Gold Wires Are Formed By Thermal Migration

June 7, 2005
Author(s)
Ganesh K. Ramachandran, Monica D. Edelstein, David L. Blackburn, John S. Suehle, Eric M. Vogel, Curt A. Richter
The formation of gold wires separated by a few nanometers is reported. Such nanometer separated gaps are formed by ramping, at ambient conditions, a bias voltage across a thin gold wire until the wire breaks or fails. Externally heating the wire does not

The Measurement of Optical Frequencies

June 7, 2005
Author(s)
Leo W. Hollberg, Scott A. Diddams, A Bartels, Tara M. Fortier, Kyoungsik Kim
Even the suggestion of counting optical frequencies in the visible (~ 500 THz) must have seemed ludicrous to many in the past, because traditional methods failed to work above about 100 GHz. Nonetheless, with some vision and new ideas a few researchers had

The NIST Kolsky Bar Data Processing System

June 7, 2005
Author(s)
Eric P. Whitenton
A new dynamic testing apparatus has been built at the National Institute of Standards and Technology (NIST) to measure dynamic material properties for machining simulation and other applications. This apparatus-the NIST Pulse Heated Kolsky Bar - is based

Electrical Properties of Nb-MoSi2-Nb Josephson Junctions

June 6, 2005
Author(s)
Yonuk Chong, Paul Dresselhaus, Samuel Benz
We present a detailed study of the electrical properties of planar Nb-MoSi2-Nb Josephson junctions. The Nb-MoSi2-Nb junction is an excellent system to study proximity-coupling in junctions with rigid superconductor/normal metal boundaries by controlling

A compact double-pass acousto-optic modulator system

June 1, 2005
Author(s)
Elizabeth A. Donley, Thomas P. Heavner, F Levi, M O. Tataw, Steven R. Jefferts
A problem that arises when using acousto-optic modulators (AOMs) to scan the laser frequency is the dependence of the beam diffraction angle on the modulation frequency. Alignment problems with AOM-modulated laser beams can be effectively eliminated by

A current-density scale for characterizing nonlinearity in high-Tc superconductors

June 1, 2005
Author(s)
Kenneth Leong, James C. Booth, Susan A. Schima
In this paper, we characterize microwave nonlinearity in a high temperature superconducting (HTS) thin film sample by measurement of a geometry-independent current-density scale j o. This quanity j specifies the strenth of a material-dependent nonlinearity

A Local Oscillator for Chip-Scale Atomic Clocks at NIST

June 1, 2005
Author(s)
Alan Brannon, J Breitbarth, Z Popovic, Vladislav Gerginov, V Shah, Svenja A. Knappe, Leo W. Hollberg, John E. Kitching
We report the first local oscillator (LO) demonstrating viability in terms of performance, size, and power, for chip scale atomic clocks (CSAC) at the National Institute of Standards and Technology in Boulder, CO. This volgate-controlled oscillator (VCO)

A Web Services Community Model for Services Provisioning

June 1, 2005
Author(s)
Z Luo, J Li, Jia Zhang
The National Software Reference Library (NSRL) of the U.S. National Institute of Standards and Technology (NIST) collects software from various sources and publishes file profiles computed from this software (such as MD5 and SHA-1 hashes) as a Reference

Active Light-Shift Stabilization in Modulated CPT Clocks

June 1, 2005
Author(s)
V Shah, P Schwindt, Vladislav Gerginov, Svenja A. Knappe, Leo W. Hollberg, John E. Kitching
We demonstrate a simple technique to significantly improve the long-term frequency stability in atomic clocks vased on coherent population trapping (CPT). In this technique an additional servo is used to control the local oscillator power level to ensure

Analysis of the Step-Diagonal Test

June 1, 2005
Author(s)
Johannes A. Soons
The step-diagonal test modifies the diagonal displacement test for machine tool performance evaluation by executing a diagonal as a sequence of single-axis motions. The proposed modification has gained interest because of the claim that the obtained

Analyzing Microstructure by Rietveld Refinement

June 1, 2005
Author(s)
Davor Balzar, N C. Popa
Rietveld refinement has a primary purpose of refining crystal structure. However, this powerful technique is being increasingly used for obtaining microstructural information, such as texture, crystallite size, strain and stress, and crystalline defect

Antenna coupled niobium bolometers for 10 (mu)m radiation detection

June 1, 2005
Author(s)
Robert Hadfield, Aaron J. Miller, Sae Woo Nam, Erich N. Grossman, Robert E. Schwall,
We report on the fabrication and testing of antenna-coupled niobium bolometers for 10-micron wavelength radiation detection. We use 20 nm thick Nb films on oxidized Si substrates. The bolometer design consists of a 1 micron x 1 micron Nb microbridge
Displaying 36526 - 36550 of 74855