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Displaying 24601 - 24625 of 73697

Generation of Ultrastable microwaves via optical frequency division

June 26, 2011
Author(s)
Tara Fortier, Matthew S. Kirchner, Jennifer A. Taylor, James C. Bergquist, Yanyi Jiang, Andrew Ludlow, Christopher W. Oates, Till P. Rosenband, Scott Diddams, Franklyn Quinlan, Nathan D. Lemke
A frequency-stabilized femtosecond laser optical frequency comb serves as a source of microwave signals having very low close-to-carrier phase noise. Comparison of two independent systems shows combined absolute phase noise of -100 dBc/Hz at an offset of 1

Understanding the Fire Hazards of Grouped Electrical Cables

June 26, 2011
Author(s)
Kevin B. McGrattan, David Stroup
CHRISTIFIRE (Cable Heat Release, Ignition, and Spread in Tray Installations during FIRE) is an Office of Nuclear Regulatory Research (RES, US NRC) program to quantify the mass and energy released from burning electrical cables. The experimental program has

Antiferromagnetic Spin Excitations in Single Crystals of Nonsuperconducting Li 1-x FeAs

June 24, 2011
Author(s)
Meng Wang, X. C. Wang, D. L. Abernathy, L. W. Harriger, H. Q. Luo, Yang Zhao, Jeffrey W. Lynn, Q. Q. Liu, C. Q. Jin, Chen Fang, Jianping Hu, Pengcheng Dai
We use neutron scattering to determine spin excitations in single crystals of nonsuperconducting Li 1¿xFeAs throughout the Brillouin zone. Although angle resolved photoemission experiments and local density approximation calculations suggest poor Fermi

Self-Assembly of Dendronized Perylene Bisimides into Complex Helical Columns

June 24, 2011
Author(s)
Virgil Percec, Mihai Peterca, Timur Tadjiev, Xiangbing Zeng, Goran Ungar, Pawaret Leowanawat, Emad Aqad, Mohammad Imam, Brad Rosen, Umit Akbey, Robert Graf, Sivakumar Sekharan, Daniel Sebastiani, Hans -. Spiess, Paul A. Heiney, Steven Hudson
The synthesis of perylene 3,4:9,10-tetracarboxylic acid bisimides (PBIs) dendronized with first generation dendrons containing 0 to 4 methylenic units (m) between the imide group and the dendron, (3,4,5)12G1-m-PBI, is reported. Structural analysis of their

Who wrote What Where: Analyzing the content of human and automatic summaries

June 23, 2011
Author(s)
Karolina K. Owczarzak, Hoa T. Dang
Abstractive summarization has been a long-standing and long-term goal in automatic summarization, because systems that can generate abstracts demonstrate a deeper understanding of language and the meaning of documents than systems that merely extract

Conformance Test Architecture and Test Suite for ANSI/NIST-ITL 1-2007

June 22, 2011
Author(s)
Fernando L. Podio, Dylan J. Yaga, Christofer J. McGinnis
The Computer Security Division of NIST/ITL supports the development of biometric conformance testing methodology standards and other conformity assessment efforts through active technical participation in the development of these standards and the

An Analysis of the Performance of Smoke Alarms

June 21, 2011
Author(s)
Thomas G. Cleary
Test results from the NIST 2008 Smoke Alarm Sensitivity Study were used in a smoke alarm performance analysis to examine the effects of pre-movement time, reduced travel speeds through smoke, and smoke optical density limit on occupant survivability given

APPLICATIONS OF HIGH-THROUGHPUT SCREENING TOOLS FOR THERMOELECTRIC MATERIALS

June 21, 2011
Author(s)
Winnie K. Wong-Ng, Howard L. Joress, Joshua B. Martin, Yonggao Y. Yan, Jihui Yang, Makoto Otani, Evan L. Thomas, Martin L. Green, Jason Hattrick-Simpers
The increased research and development on thermoelectric materials in recent years has been driven primarily by the need for improved efficiency in the global utilization of energy resources. To facilitate the search for new thermoelectric materials, we

Phase Equilibria, Crystal Chemistry and Thermoelectric Properties of Compounds in the Ca-Co-Zn-O System

June 21, 2011
Author(s)
Winnie K. Wong-Ng, Tana Luo, Wenjie Xie, Weihua Tang, James A. Kaduk, Qingzhen Huang, Yonggao Y. Yan, Soma Chattopadhyay
In the Ca-Co-Zn-O system, we have determined the tie-line relationships and the thermoelectric properties, solid solution limits, and structures of two low-dimensional cobaltite series, Ca3(Co, Zn)4O9 and Ca3(Co,Zn)2O6 at 885 C in air. In Ca3(Co,Zn)4O9

PROFICIENCY TESTING IN U.S. STATE WEIGHTS AND MEASURES LABORATORIES

June 21, 2011
Author(s)
Elizabeth Benham, Georgia L. Harris, Val R. Miller
The National Institute of Standards and Technology (NIST) Weights and Measures Division (WMD) manages a program for State Weights and Measures laboratories that includes: 1) laboratory Recognition following ISO/IEC 17025:2005 [1, 8] and sponsorship of

Specification for the Asset Reporting Format 1.1

June 21, 2011
Author(s)
David A. Waltermire, Adam Halbardier, Mark Johnson
This specification describes the Asset Reporting Format (ARF), a data model for expressing the transport format of information about assets and the relationships between assets and reports. The standardized data model facilitates the reporting, correlating

A Simple Reaction Time Scale for Under-Resolved Fire Dynamics

June 20, 2011
Author(s)
Randall J. McDermott, Kevin B. McGrattan, Jason E. Floyd
A reaction time scale model is developed for use in the eddy dissipation concept (fast chemistry limit) closure of the mean chemical source term in large-eddy simulation of fires. The novel aspect of the model is to consider a scaling regime for coarse

Absolute refractometry of dry gas to +-3 parts in 10 9

June 20, 2011
Author(s)
Patrick F. Egan, Jack A. Stone Jr.
We present a method of measuring the refractive index of dry gases absolutely at 632.8 nm wavelength using a Fabry-Perot cavity with an expanded uncertainty of -9 (coverage factor k = 2. The main contribution to this uncertainty is how well vacuum-to

Data for Thermophysical Properties of Humid Gases in Power Cycles

June 20, 2011
Author(s)
Allan H. Harvey, Mark O. McLinden, Richard A. Perkins
This report summarizes the results of work performed for DOE/NETL Interagency Agreement DE-AI26-06NT42957. The key objectives for this work were to: (1) Use results of first-principles quantum mechanics to develop a description of the thermodynamics of

Experiment at NIST towards one-electron ions in circular Rydberg states

June 20, 2011
Author(s)
Joseph N. Tan, Samuel M. Brewer, Nicholas D. Guise
An experimental effort is underway at NIST to enable tests of theory with oneelectron ions synthesized in circular Rydberg states from captured bare nuclei. Problematic effects which limit the accuracy of predicted energy levels for low-lying states are

Frequency-comb based approaches to precision ranging laser radar

June 20, 2011
Author(s)
Nathan R. Newbury, Tze-Ann Liu, Ian R. Coddington, Fabrizio R. Giorgetta, Esther Baumann, William C. Swann
The output of pulsed femtosecond lasers can be controlled to generate pulse trains with very precise timing and optical frequency. This source can be used in different ways to support precision coherent LIDAR. We will discuss several implementations of

CFD Simulations on Extinction of Co-Flow Diffusion Flames

June 19, 2011
Author(s)
Randall J. McDermott, Jukka Vaari, Jason E. Floyd
An improved flame extinguishing criterion is implemented to the Fire Dynamics Simulator (FDS) for gaseous suppressants under the lumped species model with transport-limited combustion (infinitely fast chemistry). The criterion considers the total enthalpy

Microwave near-field probes for photovoltaic applications

June 19, 2011
Author(s)
Joel C. Weber
The photoresponse of three different photovoltaic Cu(In, Ga)Se 2 (CIGS) samples as well as GaAs and silicon bulk samples is measured using near-field scanning microwave microscopy (NSMM). Modeling predicts light-dependent conductivity values for bulk

Parametric study of micropillar array solar cells

June 19, 2011
Author(s)
Heayoung Yoon, Yu A. Yuwen, Haoting Shen, Nikolas J. Podraza, Thomas E. Mallouk, Elizabeth C. Dickey, Joan A. Redwing, Christopher R. Wronski, Theresa S. Mayer
Micro/nano pillar arrays can be a promising architecture for high efficiency solar cells based on less expensive photovoltaic materials with short minority carrier diffusion lengths (Ln, p). To investigate design tradeoffs of the radial junction array
Displaying 24601 - 24625 of 73697
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