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Displaying 52376 - 52400 of 73893

Optical Computer Aided Tomography of an Inductively Coupled Discharge

March 1, 1998
Author(s)
Eric C. Benck, J R. Roberts
Optical computer aided tomography (CAT) is being investigated as a potential in situ diagnostic for measuring plasma uniformity without making assumptions concerning the plasma symmetry. The presence of an opaque vacuum chamber wall severely limits the

Personal Identification From Mugshot Ear Images

March 1, 1998
Author(s)
F E. McFadden
This work establishes the high value of ear images for personal identification from mugshot data, using the NIST database of police mugshots. It starts with a method for boundary analysis based on two innovations. First edge analysis is performed only

Round Robin Determination of Power Spectral Densities of Different Si Wafer Surfaces

March 1, 1998
Author(s)
Egon Marx, I J. Malik, Y Strausser, T Bristow, N Poduje, J C. Stover
Power spectral densities (PSDs) were used to characterize a set of surfaces over a wide range of lateral as well as perpendicular dimensions. Twelve 200-mm-diameter Si wafers were prepared and the surface finishes ranged from as-ground wafers to epitaxial

Small Angle Scattering by Dislocations

March 1, 1998
Author(s)
R Thomson, Lyle E. Levine, Gabrielle G. Long
It is shown that the small-angle scattering of x rays or neutrons by dislocations in a deformed metal, which are partially ordered into wall-like structures, is characterized by several structure factors. Principally there are associated with 1) a single

Spectral Reflectance

March 1, 1998
Author(s)
P Y. Barnes, Albert C. Parr, E A. Early
This document describes the instrumentation, standards, and techniques used to measure spectral reflectance over the ultraviolet, visible, and near infrared wavelength ranges. The organization is as follows. Part I describes the motivation for maintaining

Thin-Film Ellipsometry Metrology

March 1, 1998
Author(s)
P. Durgapal, James R. Ehrstein, Nhan Van Nguyen
A wide variety of commercial ellipsometers are available in the market today. They all measure the change in the state of polarization of light on reflection, but the techniques adopted vary from instrument to instrument. Further, the models used to

Through-the-Arc Detection of Weld Defects in Pulsed GTAW

March 1, 1998
Author(s)
Timothy P. Quinn, D C. Oakley
A through-the-arc sensing system was used to detect defects in the welding of thin-walled stainless-steel tubing. It measures the process current and voltage and passes the resulting signals through a signal processing algorithm. The arc condition number

Tip Characterization for Scanned Probe Microscope Width Metrology

March 1, 1998
Author(s)
Samuel Dongmo, John S. Villarrubia, Samuel N. Jones, Thomas B. Renegar, Michael T. Postek, Jun-Feng Song
Determination of the tip shape is an important prerequisite for converting the various scanning probe microscopies form imaging tools into dimensional metrology tools with sufficient accuracy to meet the critical dimension measurement requirements of the

Uncertainties in NIST Noise-Temperature Measurements

March 1, 1998
Author(s)
James P. Randa
Uncertainty analyses are presented for NIST measurements of noise temperature. All systems currently used in NIST calibrations of thermal-noise sources are treated. These include tuned systems for 30 and 60 MHz, coaxial total-power radiometers for 1 to 12

Uncertainty Analysis for Angle Calibrations Using Circle Closure

March 1, 1998
Author(s)
William T. Estler
We analyze two types of full-circle angle calibrations: a simple closure in which a single set of unknown angular segments is sequentially compared with an unknown reference angle, and a dual closure in which two divided circles are simultaneously

Workspace Variation of a Hexapod Machine Tool

March 1, 1998
Author(s)
J Conti, C Clinton, Li Zhang, Albert J. Wavering
A method is presented to evaluate the workspace variation of a Stewart platform based machine tool. Three sets of constraints, covering strut lengths, platform and base spherical joint angles, and strut collisions, are formulated using inverse kinematics

Hygrothermal Aging Studies of a Commercial Structural Adhesive

February 27, 1998
Author(s)
M Fernandez-Garcia, Martin Y. Chiang
This paper presents work in progress on the study of hygrothermal behavior of commercial structural adhesives in the Polymers Division at NIST. The work includes the disciplines of polymer science and applied mechanics, where the former addresses the
Displaying 52376 - 52400 of 73893
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