NOTICE: Due to a lapse in annual appropriations, most of this website is not being updated. Learn more.

Form submissions will still be accepted but will not receive responses at this time. Sections of this site for programs using non-appropriated funds (such as NVLAP) or those that are excepted from the shutdown (such as CHIPS and NVD) will continue to be updated.

U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Search Publications

NIST Authors in Bold

Displaying 29126 - 29150 of 73697

Keeping time in three dimensions

December 1, 2008
Author(s)
Christopher W. Oates
Here I review a paper by Akatsuka et al. that appears in the current volume of Nature Physics. This work describes their latest experimental results on optical lattice clocks, including the first demonstration of a 3-D lattice clock.

Overview of the TREC 2007 Question Answering Track

December 1, 2008
Author(s)
Hoa T. Dang, Diane Kelly, Jimmy Lin
The TREC 2007 question answering (QA) track contained two tasks: the main task consisting of series of factoid, list, and ``Other'' questions organized around a set of targets, and the complex, interactive question answering (ciQA) task. The main task

Production of Entangled Images by Four-Wave Mixing

December 1, 2008
Author(s)
Alberto M. Marino, Vincent Boyer, Raphael C. Pooser, Paul D. Lett
One of the most important resources in quantum mechanics is entanglement, which is characterized by correlations stronger than the ones allowed classically. As a result, it is at the basis of applications such as quantum cryptography, quantum information

Progress on a portable rubidium fountain frequency standard

December 1, 2008
Author(s)
Paul D. Kunz, Thomas P. Heavner, Steven R. Jefferts
We are developing a simple and transportable laser-cooled rubidium (Rb) atomic fountain frequency standard. The optical package for this system uses DFB (distributed feedback) diode lasers and a frequency offset locking scheme to generate the optical

PTTI Capabilities of the Modernized LORAN System

December 1, 2008
Author(s)
Kirk Montgomery, Michael A. Lombardi
This paper covers the current status and future plans of the modernized LORAN systems in North America, the European Union, Asia, & Saudi Arabia. Special focus is placed on the enhanced LORAN system in North America and Europe. These modernized systems

Smokeview: A Visualization Tool for Understanding Fire Dynamics

December 1, 2008
Author(s)
Glenn P. Forney
The purpose of fire modeling is to gain a better insight into fire dynamics and how it impacts fire safety -- not to generate large amounts of data. Gaining this insight requires visualization tools that display what the numbers generated by the model

Solid State Chemistry of Proteins: II. The Correlation of Storage Stability of Freeze-Dried Human Growth Hormone (hGH) With Structure and Dynamics in the Glassy Solid

December 1, 2008
Author(s)
Michael Pikal, Daniel Rigsbee, Michael L. Roy, Dawn Galreath, Karl J. Kovach, Bingquan S. Wang, John Carpenter, Marcus T. Cicerone
This research presents storage stability of human growth hormone, hGH, in a variety of lyophilized formulations, including systems of varying sugar:hGH weight ratios for both sucrose and trehalose. Stability was assessed at multiple time points during

Steering a Time Scale

December 1, 2008
Author(s)
Judah Levine
A time scale is a procedure for combining the data from an ensemble of clocks or frequency standards. The input data to the ensemble algorithm are generally the time (or frequency) differences between each of the members and the reference device for the

The SIM Time and Frequency Network

December 1, 2008
Author(s)
Michael A. Lombardi, Andrew N. Novick, Jose M. Lopez, Francisco Jimenez, Jean-Simon Boulanger, Raymond Pelletier, Ricardo de Carvalho, Raul Solis, Carlos Donado, Harold Sanchez, Carlos A. Quevedo, Gregory Pascoe, Daniel Perez
The Sistema Interamericano de Metrologia (SIM) consists of national metrology institutes (NMIs) located in the 34 member nations of the Organization of American States (OAS), which extends throughout North, Central, and South America, and the Caribbean

The Sixteenth Text REtrieval Conference (TREC 2007)

December 1, 2008
Author(s)
Ellen M. Voorhees
This report constitutes the proceedings of the 2007 Text REtrieval Conference, TREC 2007, held in Gaithersburg, Maryland November 6-9, 2007. TREC 2007 is the latest in a series of workshops designed to foster research in text retrieval and related

Time and Frequency Transfer Activities at NIST

December 1, 2008
Author(s)
Victor S. Zhang, Michael A. Lombardi
The National Institute of Standards and Technology (NIST) maintains one of the world s most accurate and stable time scales, and also developed and maintains the primary frequency standard for the United States. Various techniques are used to compare the

Vibration-induced PM Noise of A Rigid Optical Fiber Spool

December 1, 2008
Author(s)
Jennifer A. Taylor, Craig W. Nelson, Archita Hati, Neil Ashby, David A. Howe
Oscillators operating in field applications are subject to much more strenuous environmental effects than those in the laboratory. These environmental effects, like vibration and temperature fluctuation, have a great impact on the performance of the

A Novel Topology Control Scheme for Future Wireless Mesh Networks

November 30, 2008
Author(s)
Yi Qian, Kejie Lu, Tao Zhang, Shengli Fu
In this paper, we address the topology control issue for future wireless mesh networks (WMNs) based on the principle of service-oriented design. In particular, we propose a novel topology control scheme that attempts to maximize the overall throughput in

A Secure VANET MAC Protocol for DSRC Applications

November 30, 2008
Author(s)
Yi Qian, Nader Moayeri, Kejie Lu
Vehicular ad hoc networking is an important component of Intelligent Transportation Systems. The main benefit of vehicular ad hoc network (VANET) communication is seen in active safety systems that increase passenger safety by exchanging warning messages

Diversity Performance of a Practical Non-Coherent Detect-and-Forward Receiver

November 30, 2008
Author(s)
Michael R. Souryal, Huiqing You
We propose a non-coherent receiver for the fixed detect-and-forward relay channel and derive a closed-form tight upper bound on its bit error probability in Rayleigh fading channels. Using this upper bound, we show that the receiver achieves nearly full

Non-Coherent Amplify-and-Forward Generalized Likelihood Ratio Test Receiver

November 30, 2008
Author(s)
Michael R. Souryal
This paper proposes a simple non-coherent amplify-and-forward receiver for the relay channel and evaluates its diversity performance for Rayleigh fading channels. We use the generalized likelihood ratio test to obtain the decision rule in closed form

Security Challenges in Seamless Mobility - How to ``Handover'' the Keys?

November 30, 2008
Author(s)
Katrin Hoeper, Lidong Chen, Antonio Izquierdo Manzanares, Nada T. Golmie
In this paper, we discuss key management challenges for seamless handovers across heterogeneous wireless networks. We focus on fast access authentication protocols that allow expedited network entry by utilizing existing keying material from previous

Computational Parameters in Simulation of Microscope Images

November 28, 2008
Author(s)
Egon Marx, James E. Potzick
The simulation of microscope images computed from scattered fields determined using integral equations depend on a number of parameters that are not related to the scatterer or to the microscope but are choices made for the computation method. The effect

Integral Equations for 3-D Scattering: Finite Strip on a Substrate

November 28, 2008
Author(s)
Egon Marx
Singular integral equations that determine the exact fields scattered by a dielectric or conducting finite strip on a substrate are presented. The computation of the image of such a scatterer from these fields by Fourier optics methods is also shown.

Managing Materials Information in the Supply Chain

November 28, 2008
Author(s)
John V. Messina, Eric D. Simmon
One important aspect of sustainable manufacturing is the acquisition and management of product material information. This information may be used to improve the design and manufacturing process, facilitate recycling, and to help comply with regulations
Displaying 29126 - 29150 of 73697
Was this page helpful?