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 21151 - 21175 of 73930

Infrared Thermography for Laser-Based Powder Bed Fusion Additive Manufacturing Processes

July 26, 2013
Author(s)
Shawn P. Moylan, Eric P. Whitenton, Brandon M. Lane, John A. Slotwinski
Additive manufacturing (AM) has the potential to revolutionize discrete part manufacturing, but improvements in processing of metallic materials are necessary before AM will see widespread adoption. A better understanding of AM processes, resulting from

Porosity of Additive Manufacturing Parts for Process Monitoring

July 26, 2013
Author(s)
John A. Slotwinski, Edward J. Garboczi
Some metal additive manufacturing processes can produce parts with internal porosity, either intentionally (with careful selection of the process parameters) or unintentionally (if the process is not well understood.) Material porosity is undesirable for

Proposed E57.02 Range Measurement Performance Standard for Medium Range 3D Imaging Systems

July 26, 2013
Author(s)
David MacKinnon, Luc Cournoyer, Kamel Saidi, Geraldine Cheok, Robert Bridges, Darin Ingimarson
We present the proposed standard ASTM E57.02 "Test Method to Evaluate the Range Measurement Performance of 3D Imaging Systems in the Medium Range" (Work Item ASTM WK12373). The stated purpose of the standard is to provide metrics and procedures to evaluate

Where in the Internet is Congestion?

July 26, 2013
Author(s)
Daniel I. Genin
Understanding distribution of congestion in the Internet is a long-standing problem. Using data from the SamKnows US broadband access network measurement study, commissioned by the FCC, we explore patterns of congestion distribution in DSL and cable

Cancellation of Doppler Shifts in a Cold-Atom CPT Clock

July 25, 2013
Author(s)
Elizabeth A. Donley, Francois-Xavier R. Esnault, Eric M. Blanshan, John E. Kitching
A compact cold-atom clock based on coherent population trapping (CPT) is being developed. Long-term goals for the clock include achieving a fractional frequency accuracy of 1x10 -13 in a package of less than 10 cm 3 in volume. Here we present an overview

Character sums determined by low degree isogenies of elliptic curves

July 25, 2013
Author(s)
Dustin Moody, Christopher Rasmussen
We look at certain character sums determined by isogenies on elliptic curves over finite fields. We prove a congruence condition for character sums attached to arbitrary cyclic isogenies, and produce explicit formulas for isogenies of degree m

Effect of Supercritical Carbon Dioxide on the Thermodynamics of Model Styrene-Acrylonitrile Copolymer-Poly(methyl methacrylate) Blends Studied by Small-Angle Neutron Scattering

July 25, 2013
Author(s)
Sebnem Inceoglu, Nicholas P. Young, Andrew J. Jackson, Steven Kline, Stephane Costeux, Nitash P. Balsara
Small-angle neutron scattering was used to study a binary blend of styrene-acrylonitrile copolymer (SAN) and deuterated poly(methyl methacrylate) (dPMMA), as wellas a multicomponent mixture of SAN, dPMMA, and supercritical carbon dioxide (scSO 2). The

Significance Test with Data Dependency in Speaker Recognition Evaluation

July 25, 2013
Author(s)
Jin Chu Wu, Alvin F. Martin, Craig S. Greenberg, Raghu N. Kacker, Vincent M. Stanford
To evaluate the performance of speaker recognition systems, a detection cost function defined as a weighted sum of the probabilities of type I and type II errors is employed. The speaker datasets may have data dependency due to multiple uses of the same

A Chosen IV Related Key Attack on Grain-128a

July 24, 2013
Author(s)
Subhadeep Banik, Subhamoy Maitra, Santanu (. Sarkar, Meltem Sonmez Turan
Due to the symmetric padding used in the stream cipher Grain v1 and Grain-128, it is possible to find Key-IV pairs that generate shifted keystreams efficiently. Based on this observation, Lee et al. presented a related-Key chosen IV attack on Grain v1 and

CT head-scan dosimetry in an anthropomorphic phantom and associated measurement of ACR accreditation-phantom imaging metrics under clinically representative scan conditions

July 24, 2013
Author(s)
Ronaldo Minniti, Claudia Brunner, Stanley H. Stern, Marie I. Parry, Kish Chakrabarti
The purpose of this work was to measure radiation absorbed dose and its distribution in an anthropomorphic head phantom under clinically representative scan conditions in three widely-used computed tomography (CT) scanners, and to relate those dose values

Why there is no noon-midnight red shift in the GPS

July 24, 2013
Author(s)
Neil Ashby, Marc A. Weiss
Although the effects of solar and lunar gravitational potentials on the frequencies of orbiting GPS clocks are actually negligible, a naive calculation appears to show that such effects are significant, depending on whether the SV clock is between the

Absolute calibration of optical power and fluence rate for PDT: Report of AAPM TG140

July 23, 2013
Author(s)
Marla L. Dowell, Timothy Zhu, Christopher Bonnerup, Valdir Colussi, Jarod Finlay, Lothar Lilge, Thomas Slowery, claudio sibata
This report is primarily concerned with methods for optical calibration of laser power and light fluence rate for continuous wave (CW) light sources, predominantly used in photodynamic therapy (PDT). Dosimetry of light is very important for PDT, however

Cold atomic beam ion source for focused ion beam applications

July 23, 2013
Author(s)
Brenton J. Knuffman, Adam V. Steele, Jabez J. McClelland
We report measurements and modeling performed on an ion source based on ionization of a laser-cooled atomic beam. We show a high brightness and a low energy spread, suitable for use in next-generation, high-resolution focused ion beam (FIB) systems. Our

Computer Security Division 2012 Annual Report

July 22, 2013
Author(s)
Patrick D. O'Reilly
Title III of the E-Government Act of 2002, entitled the Federal Information Security Management Act (FISMA) of 2002, requires NIST to prepare an annual public report on activities undertaken in the previous year, and planned for the coming year, to carry

Direct measurements of mass-specific optical cross sections of single component aerosol mixtures

July 22, 2013
Author(s)
James Radney, Xiaofei Ma, Keith A. Gillis, Michael R. Zachariah, Joseph T. Hodges, Christopher D. Zangmeister
The optical properties of atmospheric aerosols vary widely, being dependent upon particle composition, morphology and mixing state. This diversity and complexity of aerosols motivates measurement techniques that can discriminate and quantify a variety of
Displaying 21151 - 21175 of 73930
Was this page helpful?