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Displaying 47651 - 47675 of 73969

Morphological Partitioning of Ethylene Defects in Random Propylene-Ethylene Copolymers

August 1, 2000
Author(s)
R G. Alamo, David L. VanderHart, Marc R. Nyden, L Mandelkern
A series of four propylene/ethylene, metallocene-catalyzed copolymer samples, with ethylene mole fractions ranging from 0.8 to 7.5 mol % and melt-crystallization histories of cooling at 1 C/min, were studied by 13C solid state NMR techniques. The principal

Multizone Modeling as an Indoor Air Quality Design Tool

August 1, 2000
Author(s)
Amy Musser
Increased public awareness and changing industry standards have highlighted the importance of indoor air quality in the building design process. At the same time, many owners would like to construct buildings that conserve energy and minimize environmental

Neutron Reflectivity Study of Diblock Formation During Reactive Blending Processes

August 1, 2000
Author(s)
Makoto Hayashi, H Grull, A R. Esker, M J. Weber, Li Piin Sung, Sushil K. Satija, Charles C. Han, TT Hashimoto
In a series of neutron reflectivity experiments, we studied the fundamental process of diblock formation during reactive blending processes of an immiscible blend comprised of normal polysulfone (hPSU) containing 30 % reactive endgroup-modified deuterated

NIST Workshop on Needs for Reference Biomaterials

August 1, 2000
Author(s)
John A. Tesk
On November 13, 1998, a workshop was held at the National Institute of Standards and Technology (NIST) to obtain a clearer assessment of the current needs for reference biomaterials (RBMs) with regard to standards, research, and regulatory purposes. In

Observation of Resonances Associated With Stereo and Regio Defects in the Crystalline Regions of Isotatic Polypropylene: Towards a Determination of Morphological Partitioning

August 1, 2000
Author(s)
David L. VanderHart, R G. Alamo, Marc R. Nyden, M S. Kim, L Mandelkern
We report defect-resonance patterns associated with 2 kinds of low-concentration defects typically found in metallocene-synthesized isotactic polypropylenes (iPPs). These defects are the simple mrrm stereo defect and the regio 2,1-erythro defect. This work

Optical Fiber Power Meter Nonlinearity Calibrations at NIST

August 1, 2000
Author(s)
Igor Vayshenker, Shao Yang, Xiaoyu X. Li, Thomas Scott, Christopher L. Cromer
We describe a system for measuring the response nonlinearity of optical fiber power meters and detectors over a wide power dynamic range at telecommunication wavelengths. The system uses optical fiber components and is designed to accommodate commonly used

Percolation Aspects of Cement Paste and Concrete - Properties and Durability

August 1, 2000
Author(s)
Edward J. Garboczi, Dale P. Bentz
Synopsis: Portland cement concrete is a composite material, where the matrix consists of portland cement paste. Cement paste forms from the hydration reaction of portland cement with water. The microstructure of cement paste changes drastically over a time

Performance Metrics for Intelligent Systems

August 1, 2000
Author(s)
John Evans, Elena R. Messina
Research into intelligent systems and intelligent control is burgeoning. However, there is no consensus on how to define or measure an intelligent system. This lack of rigor hinders the ability to measure progress in the field and to compare different

Phonons and Static Dielectric Constant in CaTiO 3 From First Principles

August 1, 2000
Author(s)
Eric J. Cockayne, Benjamin P. Burton
CaTiO 3 has a static dielectric constant that extrapolates to a value greater than 300 at zero temperature. We investigate the origin of this large dielectric response on a microscopic level, using first-principles plane-wave pseudopotential density

Possible Advantages of a Robust Evaluation of Comparisons

August 1, 2000
Author(s)
J W. Muller
Mean values, traditionally used as a location parameter in the analysis of intercomparisons, are known to lack stability against the effect of outliers. It is therefore proposed to replace (or complement) them by the use of medians, which have better

Precision Measurement With Gravity

August 1, 2000
Author(s)
J E. Faller
In this paper two questions are addressed: (1) what is precision measurement? And (2) where do ideas come from? To answer these questions, research examples are presented from the area of gravitational physics.

Pulse Transition Duration Measurements and Standards at NIST -- 1975 to 1988

August 1, 2000
Author(s)
W L. Gans, N. S. Nahman, J R. Andrews, E E. Baldwin
The techniques employed by NBS from the mid 70s through 1988 for the calibration of the pulse transition duration (TD) of a fast, step-like, electrical pulse generator are described along with the artifact requirements imposed on the pulse generator. The

Quantum Electrodynamics and the Fundamental Constants

August 1, 2000
Author(s)
Peter J. Mohr, Barry N. Taylor
The fundamental constants are evaluated by comparison of the results of critical experiments and the theoretical expressions of these results written in terms of the constants. Many of the theoretical expressions are based on quantum electrodynamics (QED)

Search Graph Formation for Minimizing the Complexity of Planning

August 1, 2000
Author(s)
Alberto Lacaze, Stephen B. Balakirsky
A large number of path planning problems are solved by the use of graph based search algorithms. There are a variety of techniques available to optimize the search within these graphs as well as thorough studies of thecomplexity involved in searching

Security for Private Branch Exchange Systems

August 1, 2000
Author(s)
David R. Kuhn
This document provides an introduction to security for private branch exchange systems (PBXs). The primary audience is agency system administrators and others responsible for the installation and operation of PBX systems. Major threat classes are explained
Displaying 47651 - 47675 of 73969
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