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Displaying 26526 - 26550 of 73929

Spectroradiometric Calibration of Telescopes using Laser Illumination of Flat Field Screens

July 15, 2010
Author(s)
Steven W. Brown, Claire E. Cramer, Keith R. Lykke, Allan W. Smith, John T. Woodward IV, Peter Doherty, Emilio Falco, Christopher W. Stubbs
It is standard practice at many telescopes to take a series of flat field images prior to an observation run. Typically the flat field consists of a screen mounted inside the telescope dome that is uniformly illuminated with a broadband light source. These

COMPARISON OF NEAR-FIELD METHODS AT NIST K. MacReynolds, M.H. Francis and D. Tamura

July 14, 2010
Author(s)
Katherine MacReynolds, Michael H. Francis, Douglas T. Tamura
A comparison of the planar, spherical and cylindrical near-field techniques was completed at the National Institute of Standards and Technology (NIST) for a Ku-band Cassegrain reflector antenna. This paper discusses the measurement results for the near-to

Measuring Security Risk of Networks Using Attack Graphs

July 14, 2010
Author(s)
Steven Noel, Lingyu Wang, Anoop Singhal, Sushil Jajodia
Today's computer systems face sophisticated attackers who combine multiple vulnerabilities to penetrate networks with devastating impact. The overall security of a network cannot be determined by simply counting the number of vulnerabilities. To accurately

Thermodynamic, Transport, and Chemical Properties of Reference JP-8

July 14, 2010
Author(s)
Thomas J. Bruno, Marcia L. Huber, Arno R. Laesecke, Eric W. Lemmon, Mark O. McLinden, Stephanie L. Outcalt, Richard A. Perkins, Beverly L. Smith, Jason A. Widegren
This report contains a summary of research conducted to develop a standard or accepted set of thermophysical properties for the aviation kerosene, JP-8. This report is the culmination of a three year effort that included the participation of most of the

Active Millimeter-Wave Imaging: Standoff Detection of Concealed Weapons

July 13, 2010
Author(s)
Randy Direen, David R. Novotny, Katherine MacReynolds
A near-field planar scanner is used to construct images of a nearby scene illuminated with millimeter-wave frequencies. We present our initial work in active millimeter-wave imaging, and how it applies to the detection of concealed weapons.

Controlled nucleation of GaN nanowires grown with molecular beam epitaxy

July 13, 2010
Author(s)
Kristine A. Bertness, Aric W. Sanders, Devin M. Rourke, Todd E. Harvey, Alexana Roshko, Norman A. Sanford
The location of GaN nanowires was controlled with essentially perfect selectivity using patterned SiNx prior to molecular beam epitaxy growth. Growth was uniform within mask openings and absent on the mask surface for over 95 % of the usable area of a 76

Effect on Flow Stress of a Rapid Phase Transition in AISI 1045 Steel

July 13, 2010
Author(s)
Timothy J. Burns, Steven P. Mates, Richard L. Rhorer, Eric P. Whitenton, Debasis Basak
New experimental data on AISI 1045 steel from the NIST pulse-heated Kolsky Bar Laboratory are presented. The material is shown to exhibit a nonequilibrium phase transformation at high strain rate. An interesting feature of these data is that the material

ANALYSIS OF SEGMENT-BY-SEGMENT ? - NTU MODELLING OF A MINICHANNEL CO2 GAS COOLER

July 12, 2010
Author(s)
Santiago M. Ballester, Jose M. Corberan, Jose Gonzalvez-Macia, Piotr A. Domanski
Most of the current air-to-refrigerant heat exchanger models use the classic ε-NTU approach. These models do not account for longitudinal conduction neither in the fin nor in the tube, transverse conduction in the tube, and for the heat conduction between

Temperature-dependent dielectric relaxation in bismuch zinc niobate thin films.

July 12, 2010
Author(s)
James C. Booth, Nathan D. Orloff, Joel Cagnon, Jiwei Lu, Susanne Stemmer
We apply broadband measurement techniques to determine the dielectric permittivity of Bi1.5Zn1.0Nb1.5O7 (BZN) thin films over the frequency range 1 kHz to 40 GHz. At room temperature, the permittivity function shows relaxation at high frequencies (1 GHz)

Computational study of the dielectric properties of [La,Sc] 2 O 3 solid solutions

July 11, 2010
Author(s)
Hiroyoshi Momida, Eric J. Cockayne, Naoto Umezawa, Takahisa Ohno
First-principles calculations were used to compute the dielectric permittivities of hypothetical [La,Sc]2O3 solid solutions in the cubic (bixbyite) and hexagonal La2O3 phases. Dielectric enhancement is predicted at small Sc concentrations due to the

Preface

July 11, 2010
Author(s)
Daniel G. Friend, Marcia L. Huber, Zhuomin M. Zhang
This is a preface to the special issues of the International Journal of Thermophysics that contains selected papers presented at the 17th Symposium on Thermophysical Properties, held in Boulder Colorado 21-26 June 2009.

Residential Heat Pump Heating Performance with Single Faults Imposed

July 11, 2010
Author(s)
Seok H. Yoon, William V. Payne, Piotr A. Domanski
A heat pump equipped with a thermostatic expansion valve (TXV) was tested in environmental chambers during steady-state no-fault and imposed-fault operation. The studied system was an R410A split residential heat pump with an 8.8 kW nominal cooling

Recent Developments in Thermoelectric Metrology at NIST

July 10, 2010
Author(s)
Winnie K. Wong-Ng, Joshua B. Martin, Nathan Lowhorn, Makoto Otani, Evan L. Thomas, Martin L. Green, Jason Hattrick-Simpers, Yonggao Y. Yan, Thanh Tran, Jihui Yang
We have successfully developed several important thermoelectric metrologies in recent years at NIST. First, a low temperature (10 K to 390 K) Seebeck coefficient Standard Reference Material (SRM™), Bi2Te3, which is crucial for inter-laboratory data

2009 Performance Metrics for Intelligent Systems (PerMIS'09) Workshop

July 9, 2010
Author(s)
Rajmohan Madhavan, Elena R. Messina
The Performance Metrics for Intelligent Systems (PerMIS) workshop is dedicated to defining measures and methodologies of evaluating performance of intelligent systems. The main theme of the ninth iteration of the workshop, PerMIS'09, addressed the question
Displaying 26526 - 26550 of 73929
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