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NIST Authors in Bold

Displaying 37951 - 37975 of 74220

Uncertainty and Traceability for the CEESI Iowa Natural Gas Facility

September 1, 2004
Author(s)
Aaron N. Johnson, Tom Kegel
This paper presents an uncertainty analysis for the CEESI Iowa natural gas calibration facility. This facility calibrates flow meters up to flows of 10.7 actual m3/s, at nominal pressures of 174 kPa. Flow meters are calibrated by a set of nine turbine

Uncertainty Propagation for NIST Visible Spectral Standards

September 1, 2004
Author(s)
J L. Gardner
Uncertainties in the NIST spectral standards for detectors and sources in the visible wavelength range are propagated from the high-accuracy cryogenic radiometer measurements, taking correlations into account at every stage. Partial correlations between

Parallel Adaptive Multilevel Methods With Full Domain Partions

August 31, 2004
Author(s)
William F. Mitchell
aptive multilevel methods are methods for solving partial differential equations that combine adaptive grid refinement with multigrid solution techniques. These methods have been shown to be very effective on sequential computers. Recently, a technique for

A Four-Terminal Current Shunt with Calculable AC Response

August 30, 2004
Author(s)
Owen B. Laug, T. M. Souders, Bryan C. Waltrip
The design of a 0.1 Ohm, four-terminal current shunt with calculable frequency dependence up to 1 MHz is described. It is intended for use as a standard for current measurements up to 10 A rms with the primary purpose of being able to tie alternating

Hydra User's Guide

August 30, 2004
Author(s)
Matthew L. Aronoff
This document is intended to be a User's Guide to Hydra. It is aimed toward the standards development engineers and other technical users who may be interested in using Hydra. Hydra is a three-dimensional XML viewer/editor that was developed to aid in

A New Technique for Estimating Frequency from GPS Carrier-Phase Time Transfer Data

August 28, 2004
Author(s)
C Hackman, Judah Levine, Tom Parker, Dirk Piester, Juergen Becker
GPS carrier-phase time transfer (GPSCP1T) offers high frequency stability at short averaging times, approaching a fractional frequency stability of 10-15 at averaging times of one day. However, a discontinuity occurs in the time transfer estimates between

Experimental Studies of Integrated Cognitive Systems

August 26, 2004
Author(s)
P Langley, Elena R. Messina
In this paper, we examine the issues that arise in the experimental study of integrated cognitive systems. We review the reasons why such artifacts are dicult to evaluate, then consider some dependent measures that can be used to characterize their

Autonomous Road Driving Arenas for Performance Evaluation

August 24, 2004
Author(s)
Christopher J. Scrapper Jr, Stephen B. Balakirsky, Brian Weiss
The development of performance metrics is critical in the evaluation and advancement of intelligent systems. Obtaining the pinnacle of intelligence in autonomous vehicles requires evolutionary standards and community support. In order to analyze and

Comparing Algorithms: Rules of Thumb and an Example

August 24, 2004
Author(s)
Stephen B. Balakirsky, Thomas R. Kramer
This paper provides twenty rules of thumb for comparing algorithms having the same function, one of which is to be selected for use in an intelligent system. The rules are illuminated by a specific example, the comparison of three algorithms for dealing

Modeling Quantum Information Systems

August 24, 2004
Author(s)
Paul E. Black, Andrew W. Lane
A simulator for quantum information systems cannot be both general, that is, easily used for every possible system, and efficient. Therefore, some systems will have aspects which can only be simulated by cunning modeling. On the other hand, a simulation

Power dissipation in a vertically integrated chip-scale atomic clock

August 24, 2004
Author(s)
John Kitching, Svenja A. Knappe, Li-Anne Liew, P Schwindt, V Shah, John Moreland, Leo W. Hollberg
The physics package of a vertically-integrated chip-scale atomic clock based on Cs has recently been demonstrated at NIST. This device requires 69 mW of electrical power to maintain the vapor cell 34 K above the temperature of the baseplate. The physics

Improvements in NIST-F1 and a Resulting Accuracy of df/f = 0.61 * 10 -15

August 23, 2004
Author(s)
Thomas P. Heavner, Steven R. Jefferts, Elizabeth A. Donley, Jon H. Shirley, Thomas E. Parker
Over the last several years we have made many improvements to NIST-F1 (a laser-cooled cesium fountain primary frequency standard) resulting in a reduction in the uncertainty by nearly a factor of 2 in the realization of the SI second at NIST. We recently

Microfabricated Atomic Frequency References

August 23, 2004
Author(s)
Svenja A. Knappe, P Schwindt, V Shah, Leo W. Hollberg, John Kitching, Li-Anne Liew, John Moreland
We report on the fabrication of a physics package for a chip-scale atomic clock with a volume of 9.5 mm^3, consuming 75 m W of power. The design is described in detail and is strongly motivated by the goal of wafer-level fabrication and assembly. A

The Cesium Physics Package Design for the PARCS Experiment

August 23, 2004
Author(s)
Eric A. Burt, William Klipstein, Steven R. Jefferts
The Primary Atomic Reference Clock in Space (PARCS) is a collaboration between the National Institute of Standards and Technology (NIST), the Jet Propulsion Laboratory (JPL) and the University of Colorado to build a laser-cooled cesium-beam atomic clock as

Theo1 Confidence Intervals

August 23, 2004
Author(s)
T Tasset, David A. Howe, Donald B. Percival
Theoretical variance #1 (Theo1) has been developed at NIST to improve the estimation of long-term frequency stability. Its square-root (Theo1-dev) has two significant improvements over the Allan deviation XX called ¿Adev" in estimlating long-term frequency

Theo1: Characterization of very long-term frequency stability

August 23, 2004
Author(s)
David A. Howe, T Tasset
Theo1 is the first new species of variance that addresses a particularly difficult measurement problem, namely, obtaining reliable estimation of frequency stability for sample periods that are long compared to the length of a data run. Theo1 has
Displaying 37951 - 37975 of 74220