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Search Publications

NIST Authors in Bold

Displaying 47576 - 47600 of 73830

The NIST Model for Role-Based Access Control: Towards a Unified Standard

July 26, 2000
Author(s)
R. Sandhu, David F. Ferraiolo, D. Richard Kuhn
This paper describes a unified model for role-based access control (RBAC). RBAC is a proven technology for large-scale authorization. However, lack of a standard model results in uncertainty and confusion about its utility and meaning. The NIST model seeks

Creeping Flame Spread Along Fuel Cylinders in Forced and Natural Flows and Microgravity

July 20, 2000
Author(s)
M A. Delichatsios, R A. Altenkirch, Matthew Bundy, S Bhattacharjee, L Tang, K Sacksteder
Semianalytical expressions are developed for creeping flame spread parallel to a fuel cylinder axis so that spread rates measured or predicted for flat surfaces over the same material can be directly used for cylindrical surfaces. Two phenomena are

Temperature Dependence of the Formal Reduction Potential of Putidaredoxin

July 20, 2000
Author(s)
Vytautas Reipa, Marcia J. Holden, M P. Mayhew, V L. Vilker
Putidaredoxin (Pdx), a [2Fe-2S] redox protein of size M r transfers two electrons in two separate steps from the flavin containing putidaredoxin reductase to the heme protein, cytochrome CYP101 in the P450cam catalytic cycle. It has recently come to light

CIO Cyber Security Notes

July 19, 2000
Author(s)
J E. Frye
The CIO Cyber Security Notes will be published six times a year and distributed to the senior-level CIOs and senior-level executives within the Federal government. Its purpose is to heighten awareness of cyber security trends and issues. It will report

The Challenge of Intelligent Systems

July 19, 2000
Author(s)
A Meystel, Elena R. Messina
This paper analyzes the meaning of intelligence within the domain of intelligent control. Because of historical reasons, there are varying and diverse definitions of what constitutes an intelligent control system. Due to the multidisciplinary nature of

Flammability Properties of Polymer-Layered-Silicate Nanocomposites, Polypropylene and Polystyrene Nanocomposites

July 17, 2000
Author(s)
Jeffrey W. Gilman, C L. Jackson, A B. Morgan, Richard H. Harris Jr., E Manias, E P. Giannelis, M Wuthenow, David Hilton, S H. Phillips
Our continuing study of the mechanism of flammability reduction of polymer-layered-silicate nanocomposites has yielded results for polypropylene-graft-maleic anhydride and polystyrene-layered-silicate nanocomposites using montmorillonite and

Automated Parameter Extraction Software for Advanced IGBT Modeling

July 10, 2000
Author(s)
Allen R. Hefner Jr., Sebastien Bouche
A software package for extracting parameters used in advanced IGBT models is presented. In addition, new model equations and extraction procedures are introduced that more accurately describe a wide range of IGBT types including the recently developed Warp

1-cm Collimated Source for Use in Infrared Calibrations

July 1, 2000
Author(s)
Beverly Klemme, Timothy M. Jung, Adriaan C. Carter, Eric L. Shirley, Steven R. Lorentz, Raju V. Datla
A 1 cm collimated source has been developed and tested for calibration of detectors in the 2 m to 8 m range. This source will be used to calibrate the Transfer Radiometer (BXR) currently under development at NIST. Also, the results of the test of this

A Nanocomposite Poly(Methyl-Methacrylate) Bone Cement

July 1, 2000
Author(s)
A H. Gomoll, A Bellare, W Fitz, T S. Thornhill, R D. Scott, P R. Jemian, Gabrielle G. Long
Poly(methyl methacrylate) (PMMA) based orthopaedic bone cements contain 1-3 micro υ size radiopacifier particles. Incomplete dispersion of these particles leads to the presence of 50-200 micro υ size agglomerates. These large defects are sites of high

A Visualization Approach to Dealing with Log Data

July 1, 2000
Author(s)
Michelle P. Steves, Emile L. Morse
The CollabLogger is a visual tool that supports usability analyses of human-computer interaction in a team environment. Participants in our computer-mediated activity were engaged in a small-scale manufacturing testbed project. Interactions of the group

Abrasive Machining of Glass-Ceramics With a Dental Handpiece

July 1, 2000
Author(s)
X Dong, L Yin, S Jahanmir, L K. Ives, E D. Rekow
Machinable glass ceramics are used to prepare dental restorations with modern dental CAD/CAM systems. Unfortunately, little is understood about the influence of mahining parameters on material removal rates and any damage which could be introduced into the

Activity Model: Ship Repair and Conversion

July 1, 2000
Author(s)
Yung-Tsun Lee, Swee K. Leong, Charles R. McLean
This document presents an activity model that identifies the functions involved in the ship repair and conversion industry, and the information flows required to perform those functions. The activity model presented in this document is using the Integrated

Agent Based Services for B2B Electronic Commerce

July 1, 2000
Author(s)
Yun Peng, Nenad Ivezic, Thomas R. Rhodes, N Fong
The potential of agent-based systems has not been realized yet, in part, because of the lack of understanding how the agent technology support industrial needs and emerging standards. The area of business-to-business electronic commerce (b2b e-commerce) is

AlGaAs Composition Measurements from In Situ Optical Reflectance

July 1, 2000
Author(s)
Kristine A. Bertness, J T. Armstrong, Ryna B. Marinenko, Larry Robins, Albert J. Paul, Joseph G. Pellegrino, Paul M. Amirtharaj, Deane Chandler-Horowitz
We measure the composition of AlGaAs layers during epitaxial crystal growth using in situ normal-incidence optical reflectance supported by independent methods of measuring growth rate. The results are compared with conventional ex situ characterization.

An Auto-Focusing Method in Microscopic Testbed for Optical Discs

July 1, 2000
Author(s)
Xiao Tang, P L'Hostis, Y Xiao
An auto-focusing method is described and practically applied to an optical disc test-bed. In this application, an optical microscope was used to create clear pit images of optical discs. A CCD camera generated the graphic signals for the images. A standard

An Electrically Substituted Bolometer as a Transfer Standard Detector

July 1, 2000
Author(s)
Joseph P. Rice
We have developed an electrically substituted bolometer (ESB) to serve as a portable transfer-standard detector over the full wavelength range from 200 nm to 20 m. The ESB is designed to provide a direct transfer of the optical power scale from the NIST

An Open Architecture Inspection System

July 1, 2000
Author(s)
Elena R. Messina, Hui-Min Huang, Harry A. Scott
The benefits of open architectures are not currently available for most manufacturing equipment. We describe a testbed for experimenting with an open architecture controller for an inspection system. An initial taxonomy of categories of openness is

Analysis of Threshold Effects in Ultracold Atomic Collisions

July 1, 2000
Author(s)
F H. Mies, M -. Raoult
At the ultracold temperatures which occur in cold atom traps and Bose-Einstein condensates only a few partial waves contribute to the scattering of ground-state alkali atoms and cross sections are extremely sensitive to threshold effects. We present an
Displaying 47576 - 47600 of 73830
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