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NIST Authors in Bold

Displaying 25401 - 25425 of 74684

Optimization of Cement and Fly Ash Particles to Produce Sustainable Concretes

August 1, 2011
Author(s)
Dale P. Bentz, Andrew Hansen, John Guynn
In the drive to produce more sustainable concretes, considerable emphasis has been placed on replacing cement in concrete mixtures with more sustainable materials, both from a raw materials cost and a CO2 footprint perspective. High volume fly ash

Springer Handbook of Metrology and Testing, Electrical Properties

August 1, 2011
Author(s)
Jan Obrzut, Bernd Schumacher, Heinz-Gunter Bach, Petra Spitzer
The dielectric properties of materials are used to describe electrical energy storage, dissipation and energy transfer. The most relevant physical processes in dielectric materials from the practical view point are those which result in power loss

SRM 1450d, Fibrous-Glass Board, for Thermal Conductivity from 280 K to 340 K

August 1, 2011
Author(s)
Robert R. Zarr, Amanda C. Harris, John F. Roller, Stefan D. Leigh
Thermal conductivity measurements at and near room temperature are presented as the basis for certified values of thermal conductivity for SRM 1450d, Fibrous Glass Board. The measurements have been conducted in accordance with a randomized full factorial

STR Sequence Analysis for Characterizing Normal, Variant, and Null Alleles

August 1, 2011
Author(s)
Margaret C. Kline, Carolyn R. Steffen, John M. Butler, Amy Decker
DNA sequence variation is known to exist in and around the repeat region of short tandem repeat (STR) loci used in human identity testing. While the vast majority of STR alleles measured in forensic DNA laboratories worldwide type as "normal" alleles

Trapping and Release of Citrate-Capped Gold Nanoparticles

August 1, 2011
Author(s)
Darwin R. Reyes-Hernandez, Geraldine I. Mijares, Brian J. Nablo, Kimberly A. Briggman, Michael Gaitan
An electrical method to trap and release charged gold nanoparticles on and from the surface of alkanethiol self-assembled-monolayer (SAM) modified gold electrodes is presented. Gold nanoparticle (GNP) coated electrodes were formed by immersing amine

A Bayesian Statistical Model for Hybrid Metrology to Improve Measurement Accuracy

July 31, 2011
Author(s)
Richard M. Silver, Nien F. Zhang, Bryan M. Barnes, Jing Qin, Hui Zhou, Ronald G. Dixson
We present a method to combine measurements from different techniques that reduces uncertainties and can improve measurement throughput. The approach directly integrates the measurement analysis of multiple techniques that can include different

Comparing Room Temperature and Cryogenic Cesium Fountains

July 31, 2011
Author(s)
Steven R. Jefferts, Thomas P. Heavner, Thomas E. Parker, Jon H. Shirley, Elizabeth A. Donley, Filippo Levi, Davide Calonico, C Calosso, Giovanni Costanzo, B. Mongino
We have compared the frequency of a room temperature cesium fountain primary frequency standard with that of a cryogenic (~80K) cesium fountain. This comparison yields a measurement of the blackbody frequency shift of the room temperature fountain.

Coordinating GPS Calibrations Among NIST, NRL, USNO, PTB, and OP

July 31, 2011
Author(s)
Marc A. Weiss, Victor S. Zhang, J White, K Senior, Demetrios Matsakis, S. Mitchell, P Uhrich, D Valat, W Lewandowski, G. Petit, Andreas Bauch, T. Feldman, A. Proia
Reviewing calibration results over the history since early 1980’s among several labs shows very mixed results. The best stabilities of receivers, as given by calibrations, are of the order of a few ns or better over a year, though many results are quite a

Improving the stability and accuracy of the Yb optical lattice clock

July 31, 2011
Author(s)
Andrew D. Ludlow, Yanyi Jiang, Nathan D. Lemke, Jeffrey A. Sherman, J. von Stecher, Richard W. Fox, Long-Sheng Ma, A.M. Rey, Christopher W. Oates
We report results for improving the stability and uncertainty of the NIST $^{171}$Yb lattice clock. The stability improvements derive from a significant reduction of the optical Dick effect, while the uncertainty improvements focus on improved

Limited Live-time Measurements of Frequency Spectra

July 31, 2011
Author(s)
David A. Howe, Neil Ashby, Danielle G. Lirette, Archita Hati, Craig W. Nelson
Frequency-difference-of-arrival (FDOA) can be used to monitor and track an emitter’s location by observing Doppler frequency shifts of the carrier during short pulsed transmissions. This specific application needs to consider two frequency-stability levels

MOT Loading Enhancement with Stimulated Light Forces

July 31, 2011
Author(s)
Elizabeth A. Donley, Tara C. Liebisch, Eric M. Blanshan, John E. Kitching
We demonstrate atom number enhancement in a magneto-optical trap (MOT) by use of bichromatic cooling to slow an atomic beam that is loaded into a MOT. Bichromatic cooling employs stimulated emission to apply strong cooling forces that are not limited by

Residual PM Noise Evaluation of Radio Frequency Mixers

July 31, 2011
Author(s)
Corey A. Barnes, Archita Hati, Craig W. Nelson, David A. Howe
Direct observation of phase modulated (PM) noise is often difficult due to the high dynamic range that exists between the carrier and the modulated sidebands. A common tool used to reduce the dynamic range is the phase detector, which removes the carrier

Status of a compact cold-atom CPT frequency standard

July 31, 2011
Author(s)
Elizabeth A. Donley, Francois-Xavier R. Esnault, John E. Kitching, Eugene N. Ivanov
We describe the main progress towards the realization of a cold atom frequency standard based on coherent population trapping (CPT). We explain our particular CPT configuration and give details on the experimental setup.

Synchronizing Computer Clocks Using Kalman Filters

July 31, 2011
Author(s)
Judah Levine
I have used the Kalman Filter algorithm to improve the link between the Internet Time Servers operated by the National Institute of Standards and Technology (NIST) and the primary atomic clock ensemble in Boulder, which realizes UTC(NIST) and which is used
Displaying 25401 - 25425 of 74684
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