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Displaying 52126 - 52150 of 74343

The Growth Kinetics of Nanocrystalline ZnO Colloidal Solutions

September 11, 1998
Author(s)
E M. Wong, John E. Bonevich, P C. Searson
Colloidal chemistry techniques were used to synthesize ZnO particles in the nanometer size regime. Although the synthesis and unique properties of these materials are well known, the kinetics of the growth process are not well understood. The particle

A Brief History of Early Product Data Exchange Standards

September 1, 1998
Author(s)
Barbara L. Goldstein, Sharon J. Kemmerer, Curtis H. Parks
The following paper traces the history of product data exchange standards from the physical model through electronic representations such as IGES. This paper provides an understanding of the early efforts leading to ISO 10303--Standard for the Exchange of

A New Method of Certifying Standardized Rockwell Hardness Test Blocks

September 1, 1998
Author(s)
Samuel R. Low III, Walter S. Liggett Jr, David J. Pitchure
Rockwell hardness test blocks, whether standardized at the primary national laboratory level or by secondary commercial laboratories, have been certified historically by determining an average hardness value for the test surface of the block. However

A Strain-Based Methodology for High Temperature Lifetime Prediction

September 1, 1998
Author(s)
Sheldon M. Wiederhorn, William E. Luecke, Ralph Krause
In structural materials, lifetime is often strain-determined. Once a part exceeds its allowable strain, its functional integrity is lost. Although most ceramics are designed to a brittle failure criterion, silicon nitride at the temperatures expected in

Accuracy Differences Among Photomask Metrology Tools--and Why They Matter

September 1, 1998
Author(s)
James E. Potzick
A variety of different kinds of photomask critical dimension (CD) metrology tools are available today to help meet current and future metrology challenges. These tools are based on different operating principles, and have differing cost, throughput

Acid-Assisted Consolidation of Silver Alloys for Direct Fillings

September 1, 1998
Author(s)
F Eichmiller, Kathleen M. Hoffman, A A. Guiseppetti, M M. Wray, R J. Avers
Silver-rich metal powders cold-welded by consolidation have been investigated as possible direct dental filling material. The surface of the silver powder must undergo an acid treatment to remove existing contaminants and prevent formation of new surface

Algorithms for Fresnel Diffraction at Rectangular and Circular Apertures

September 1, 1998
Author(s)
Klaus Mielenz
This paper summarizes the theory of Fresnel diffraction by plane rectangular and circular apertures with a view toward numerical computations. Approximations found in the earlier leterature, and now obsolete, have been eliminated and replaced by algorithms

Anisotropy of Interfaces in an Ordered HCP Binary Alloy

September 1, 1998
Author(s)
John W. Cahn, S C. Han, Geoffrey B. McFadden
A multiple-order parameter mean field theory of ordering on a binary hexagonal-close-packed (HCP) crystal structure is developed, and adapted to provide a continuum formulation that incorporates the underlying symmetries of the HCP crystal in both the bulk

Are the Formulas for Mode-Field Diameter Correct?

September 1, 1998
Author(s)
Ronald C. Wittmann, M. Young
We have found conceptual problems with the far-field formula 1 for mode field diameter First, the formulation is incomplete in that it ignores the obliquity factor; second, it assumes that the field at the end of a truncated fiber is identical to the mode

Basic Concepts and Methods for Keeping Autonomous Ground Vehicle Formations

September 1, 1998
Author(s)
Yigal Moscovitz, Nicholas DeClaris
A desirable basic behavior of a group of autonomous vehicles while in motion is to keep a predefined formation. Normally units are trained to move in formation according to an operational status. Past experience determines the formation for given
Displaying 52126 - 52150 of 74343
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