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Displaying 49651 - 49675 of 73898

Calibration of Dissipation Factor Standards

April 1, 1999
Author(s)
Eric D. Simmon, Gerald FitzPatrick, O. Petersons
Working standards for dissipation factor (D) standards obtained by connecting a shielded three-terminal capacitor in series with a shielded precision resistor have been developed for calibration purposes. Precision conductance boxes have been built for use

Do We Need a Roadmap?

April 1, 1999
Author(s)
Herbert S. Bennett, Joseph G. Pellegrino, D. L. Rode, Thomas J. Shaffner, David G. Seiler

Dynamical Diffraction and X-Ray Standing Waves from Atomic Planes Normal in a Twofold Symmetry Axis of the Quasicrystal A1PdMn

April 1, 1999
Author(s)
Terrence J. Jach, Yanbao Zhang, R. Colella, M. De Boissieu, M. Boudard, A. I. Goldman, T Lograsso, D W. Delaney, S. Kycia
We have observed dynamical diffraction in the [024024] and[046046] reflections of the icosahedral quasicrystal A1PdMn in the back-reflection geometry (θ B = 90 ). The x-ray fluorescence from the Al and Pd atoms exhibits strong standing wave behavior

Electron Interactions With Cl 2

April 1, 1999
Author(s)
Loucas G. Christophorou, James K. Olthoff
Low energy electron interactions with the Cl 2 molecule are reviewed. Information is synthesized and assessed on the cross sections for total electron scattering, total rotational excitation, total elastic electron scattering, momentum transfer, total

Elemental and Molecular Imaging of Human Hair Using Secondary Ion Mass Spectrometry

April 1, 1999
Author(s)
John G. Gillen, S V. Roberson, C M. Ng, M Stranick
Secondary ion mass spectrometry (SIMS) is used to image the spatial distribution of elemental and molecular species on the surface and in cross-sections of doped human hair using a magnetic sector SIMS instrument operated as an ion microprobe. Analysis of

Evaluation of Guarded High-Resistance Hamon Transfer Standards

April 1, 1999
Author(s)
Dean G. Jarrett
An improved design for a guarded transfer standard in the resistance range 1 M ω to 100 G ω is described. Existing transfer standards and their limitations are reviewed along with a description of guard circuit theory. Measurements made to evaluate the

Extension of Voltage Range for Power and Energy Calibrations

April 1, 1999
Author(s)
O. Petersons, Thomas L. Nelson, Nile M. Oldham, Gerald FitzPatrick
A special purpose ac voltage divider system with ratios of 600, 480, 360, 277, and 240 V to 120 V has been developed to extend the range of primary electric power calibrations from 120-600 V at 50 and 60 Hz. The developmental goal has been to realize ac

Fabrication of High-Value Standard Resistors

April 1, 1999
Author(s)
Ronald F. Dziuba, Dean G. Jarrett, L. L. Scott, Andrew J. Secula
The National Institute of Standards and Technology (NIST) has fabricated stable, transportable 10 MΩ} and 1 GΩ} standard resistors for use in an international comparison of high resistances. This fabrication process is being applied to the construction of

Forward

April 1, 1999
Author(s)
Norman B. Belecki
The National Institute of Standards and Technology (NIST) hosted the 1998 Conference on Precision Electromagnetic Measurements (CPEM'98) in the Washington Renaissance Hotel, Washington, DC, the week of July 6-10, 1998. In it, 506 metrologists, physicists

Frequency Comparison of 127 I 2 -Stabilized Nd: YAG Laser

April 1, 1999
Author(s)
F L. Hong, K Ishikawa, J Yoda, J Ye, L -. Ma, John L. Hall
A first international comparison of I 2 -stabilized Nd: YAG lasers has been made between the National Research Laboratory of Metrology (NRLM), Tsukuba, Japan, the Joint Institute for Laboratory Astrophysics JILA (formerly the Joint Institute for Laboratory

Generation of Different UHMWPE Particle Shape by Wear Through Surface Texturing

April 1, 1999
Author(s)
H. W. Fang, M C. Shen, U Cho, John A. Tesk, A Christou, Stephen M. Hsu
Ultra-high molecular weight polyethylene (UHMWPE) wear particles in replaced joints have been linked to biochemical reactions that eventually lead to loosening of prosthesis. Several studies have shown that UHMWPE produces a wide range of particle sizes
Displaying 49651 - 49675 of 73898