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Displaying 42526 - 42550 of 73829

Calibration of Nonreciprocal Radar Systems

November 14, 2002
Author(s)
Lorant A. Muth
The calibration of nonreciprocal radars has been studied extensively. Here we present a robust calibration procedure using Fourier analysis of back-scatter data from a rotating dihedral. We derive a set of nonlinear equations in terms of the Fourier

Calibrating Photoreceiver Response to 110 GHz

November 13, 2002
Author(s)
Tracy S. Clement, Dylan F. Williams, Paul D. Hale, Juanita M. Morgan
We have measured the magnitude and phase responses of a photoreceiver to 110 GHz using a calibrated electro-optic sampling system. The frequency range of the calibration is limited only by our 1 mm coaxial connectors.

Composition standards for III-V semiconductor epitaxial films

November 11, 2002
Author(s)
Kristine A. Bertness, Lawrence H. Robins, J T. Armstrong, Ryna B. Marinenko, Albert J. Paul, Marc L. Salit
A program is underway at NIST to establish standard reference materials (SRMs) for the calibration of instruments used to measure the chemical composition of epitaxially grown III-V semiconductor thin films. These SRMs are designed for the calibration of

Ex-situ Characterization of InGaAsP

November 11, 2002
Author(s)
Alexana Roshko, Kristine A. Bertness
An interlaboratory comparison was undertaken to assess differences in X-ray and photoluminescence measurements from different laboratories. Six InGaAsP specimens, with nominal photoluminescence peak wavelengths of 1.1, 1.3 and 1.5 υm, were measured

Trace water detection in semiconductor-grade phosphine gas

November 11, 2002
Author(s)
Kristine A. Bertness, Susan Y. Lehman, Joseph T. Hodges, H. H. Funke, Mark W. Raynor
We are applying cavity ring-down spectroscopy (CRDS) to measure water concentrations in nitrogen and, for the first time to our knowledge, in phosphine. Semiconductor-grade phosphine cylinders from different suppliers contained water in the several ppm

Analysis of Phase-Dependent RCS Measurements

November 8, 2002
Author(s)
Lorant A. Muth, Timothy Conn
Free space coherent radar cross section measurements on a moving target will trace a circle centered on the origin of the complex (I,Q) plane. Noise will introduce only small random variations in the radius of the circle. In real measurement configurations

Methods to Estimate and Reduce Leakage Bias Errors in Planar Near-Field Measurements

November 8, 2002
Author(s)
Allen C. Newell, Jeffrey R. Guerrieri, Katherine MacReynolds
This paper describes two methods that can be used to measure the leakage signals, predict the effect on the far-field pattern and correct the measured data for leakage bias errors without additional near-field measurements. One method is an extension and

Spherical Near-Field Antenna Measurements Using Nonideal Measurement Locations

November 8, 2002
Author(s)
Ronald C. Wittmann, Bradley Alpert, Michael H. Francis
We introduce a near-field spherical scanning algorithm that relaxes the usual condition requiring data points to be on a regular spherical grid. Computational complexity is of the same order as for the standard (ideal-positioning) spherical-scanning

Spherical Scanning Measurements Using Truncated Data Sets

November 8, 2002
Author(s)
Ronald C. Wittmann, Carl F. Stubenrauch, Michael H. Francis
We discuss the mitigation of truncation errors in spherical scanning measurement. The main emphasis is the spherical harmonic representation of probe transmitting and receiving functions; however, our method is applicable to near-field measurement of

SplitC Measurement Software

November 8, 2002
Author(s)
Michael D. Janezic
SplitC is a software package for measuring the permittivity and loss tangent of dielectric materials using a split-cylinder resonator. A new theoretical model for the split-sylinder resonator has been incorporated into SplitC, thereby improving the

Ultra-Wideband Antenna Pattern Characterization in a Non-Ideal EM Facility

November 8, 2002
Author(s)
Jason Veneman, David R. Novotny, Chriss A. Grosvenor, Robert T. Johnk, Seturnino Canales
We present and analyze a procedure for performing relative, ultra-wideband antenna pattern measurements in a non-ideal EM facility. Ultra-wideband, short-impulse, TEM horn transmission measurements were performed and compared with computer-modeled

Ultra-Wideband TEM-Horn Antenna Design using Numerical Methods

November 8, 2002
Author(s)
Chriss A. Grosvenor, David R. Novotny, Jason Veneman, Seturnino Canales
TEM, time-domain antennas are designed to reproduce accurately the time characteristics of an impulsive, incoming field. The response to the fields must be constant in amplitude and linear in phase for minimal distortion. Numerical techniques are employed

Optimality Conditions for Hierarchical Control

November 7, 2002
Author(s)
P Boggs, Anthony J. Kearsley, J W. Tolle
Abstract As part of the study of techniques for solving PDE-constrained optimization problems, we consider the approximate pointwise control of a linear parabolic system with multiple targets. Assuming a hierarchy among the objectives, we derive optimality

Federal S/MIME V3 Client Profile

November 5, 2002
Author(s)
C M. Chernick
S/MIME (Secure / Multipurpose Internet Mail Extensions) is a set of specifications for securing electronic mail. S/MIME is based upon the widely used MIME standard and describes a protocol for adding cryptographic security services through MIME

2002 ITL Technical Accomplishments

November 1, 2002
Author(s)
Elizabeth B. Lennon
This report describes the activities and accomplishments of the Information Technology Laboratoy at the National Institute of Technology in 2002.

Acoustophoretic Characterization of Cement Suspensions

November 1, 2002
Author(s)
Robert J. Flatt, Chiara C. Ferraris
Acoustophoresis has been used to study the evolution of the surface potential of hydrating cement suspensions because it is potentially capable of measuring zeta potentials of cement suspensions at concentrations high enough not to modify ion/particle

Analysis of [nu] 2 , [nu] 4 Infrared Hot Bands of 32 S 16 O 3 : Resolution of the Puzzle of the V 1 CARS Spectrum

November 1, 2002
Author(s)
J Barber, E T. Chrysostom, Tony Masiello, J Nibler, A G. Maki, A Weber, Thomas A. Blake, R L. Sams
Further analysis of the high-resolution (0.0015 CM -1) infrared spectrum of 32S 160 3 has led to the assignment of more than 3100 hot band transitions from Ņ2 and Ņ4 levels to the states 2Ņ 2 (1=0), {nu] 2 + Ņ 4 (l= 1), and 2Ņ 4 (l=0, 2). These levels are

Analysis of the Isoelectric Point in Moderately Concentrated Alumina Suspensions Using Electroacoustic and Streaming Potential Methods

November 1, 2002
Author(s)
Vincent A. Hackley, J Patton, Lin-Sien H. Lum, R Wasche, H Abe, M Naito, Y Hotta, H Pendse
Alumina suspended in aqueous electrolytic solution was used as a model ceramic suspension to investigate the measurement precision and influencing factors for the determination of the isoelectric point (IEP) in moderately concentrated systems. Techniques
Displaying 42526 - 42550 of 73829
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