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Displaying 32051 - 32075 of 73929

Evaluating a Ranging Protocol For 3D Imaging Systems

September 19, 2007
Author(s)
Geraldine S. Cheok, Kamel S. Saidi, Alan M. Lytle
In 2006, the ASTM E57 committee was established to develop standards for 3D imaging systems. A 3D imaging system is a non-contact instrument that is used to measure the range and bearing to and/or the 3D coordinates of points on an object or within a

Feasibility of Using a Concrete Mixing Truck as a Rheometer(Orlando, Florida)

September 19, 2007
Author(s)
Chiara F. Ferraris, Roy Cooley, Joe Grein, Max A. Peltz, Michael Topputo, Steve Verdino
The goal of the tests reported here was to further determine the feasibility of using a concrete mixing truck as a rotational rheometer. This work is the continuation of preliminary tests [ , ] that seemed to indicated that the yield stress and the plastic

Simplified motional heating rate measurements of trapped ions

September 19, 2007
Author(s)
Ryan Epstein, Signe Seidelin, Dietrich G. Leibfried, Janus Wesenberg, John J. Bollinger, Jason Amini, Brad R. Blakestad, Joseph W. Britton, Jonathan Home, Wayne M. Itano, John D. Jost, Emanuel H. Knill, C. Langer, R. Ozeri, Nobuyasu Shiga, David J. Wineland
We measure motional heating rates of trapped atomic ions, a factor that influences multi-ion quantum logic gate fidelities. Two simplified techniques are developed for this purpose: one relies on Raman sideband detection implemented with a single laser

Guided Data Capture (GDC) 5.0

September 17, 2007
Author(s)
Vladimir Diky, Robert D. Chirico, Robert N. Goldberg, Michael D. Frenkel
Guided Data Capture (GDC) 5.0 includes capture capabilities for biochemical substances and selected biothermodynamic properties. A key characteristic of data capture for much biothermodynamic data arises from the need to fully specify relatively complex

Nanowire placement with ink jet heads

September 16, 2007
Author(s)
Kristine A. Bertness, Christopher M. Dodson, Paul T. Blanchard, Norman Sanford, Ross N. Mills
We show that thermal ink jet printheads can be used to place GaN nanowires on patterned substrates. The semiconductor nanowires have diameters ranging from 70 to 300 nm and lengths from 5 υm to 20 υm. They were dispersed in alcohol-water solutions for

Nucleation and propagation mechanisms for catalyst-free growth of GaN nanowires

September 16, 2007
Author(s)
Kristine A. Bertness, Devin M. Rourke, Alexana Roshko, Lorelle Mansfield, Aric W. Sanders, Todd E. Harvey, Norman A. Sanford
Nucleation of GaN nanowires without catalysts in molecular beam epitaxy is shown to be a distinct process from nanowire propagation. Nanowire growth is relatively insensitive to starting conditions once the nanowire morphology is established, and is driven

Persistent photoconductivity studies of c-axis GaN nanowires grown by MBE

September 16, 2007
Author(s)
Norman Sanford, Paul T. Blanchard, Kristine A. Bertness, Alexana Roshko, Beau Burton, Lorelle Mansfield, John B. Schlager, Steven George, Aric Sanders
Photoconductivity (PC) and persistent photoconductivity (PPC) were measured on c-axis GaN nanowires (NWs) grown by catalyst-free nitrogen plasma assisted MBE on Si(111) substrates. Unintentionally doped n-type NWs from two separate growth batches were

Time-resolved photoluminescence study of GaN nanowires grown by catalyst-free MBE

September 16, 2007
Author(s)
John B. Schlager, Kristine A. Bertness, Paul T. Blanchard, Norman A. Sanford
We report steady-state and time-resolved photoluminescence (PL & TRPL) measurements on individual GaN nanowires that were grown by nitrogen-plasma-assisted, molecular beam epitaxy on Si(111) and subsequently dispersed onto fused quartz substrates for

6th Annual PKI R&D Workshop "Applications-Driven PKI" Proceedings

September 13, 2007
Author(s)
William T. Polk, Kent Seamons
NIST hosted the sixth Annual Public Key Infrastructure (PKI) Research Workshop on April 17-19, 2007. The two and a half day event brought together PKI experts from academia, industry, and government had a particular interest in novel approaches to

Area Measurements of Apertures for Exo-Atmospheric Solar Irradiance for JPL

September 13, 2007
Author(s)
Maritoni A. Litorja, Bettye C. Johnson, J B. Fowler
A comparison of the area measurements of the limiting apertures used for total solar irradiance measurements in the Active Cavity Radiometer Irradiance Monitor II (ACRIM II) and Active Cavity Radiometer Irradiance Monitor III (ACRIM III) were conducted

Manipulation of the Collisional Frequency Shift in Caesium Fountain Clocks

September 13, 2007
Author(s)
K Szymaniec, W Chalupczak, S Weyers, R. Wynands, Eite Tiesinga, Carl J. Williams
The frequency shift due to atomic collisions is a major, and in some cases the dominant, limitation to the accuracy of caesium fountain primary frequency standards. A correction for this shift is usually obtained by measuring the frequency of the standard

SDO EVE CCD and Thin Foil Filter Characterization and Selection

September 13, 2007
Author(s)
Matthew Triplett, David Croster, Thomas N. Woods, Francis Eparvier, Phillip Chamberlin, Gregory D. Berthiaume, David Weitz, Robert E. Vest
The NASA Solar Dynamics Observatory (SDO), scheduled for launch in 2008, incorporates a suite of instruments including the EUV Variability Experiment (EVE). The EVE instrument package contains grating spectrographs used to measure the solar extreme

SDO EVE ESP Radiometric Calibration and Results

September 13, 2007
Author(s)
Leonid Didkovsky, D L. Judge, Seth Wieman, T N. Woods, Phillip Chamberlin, Andrew Jones, Francis Eparvier, Matthew Triplett, Donald Woodraska, D R. McMullin, Mitchell L. Furst, Robert E. Vest
The Solar Dynamics Observatory (SDO) Extreme ultraviolet Solar Photometer (ESP), as a part of the Extreme ultraviolet Variability Experiment (EVE) suite of instruments, was calibrated at the National Institute of Standards and Technology (NIST) on the

Universal behaviour of silica suspensions gelled under shear

September 13, 2007
Author(s)
Howard J. Hanley, Chris Muzny, J Bartlett, E. Drabarek
The shear influenced gelation of three aqueous suspensions consisting of silica particles of nominal diameter 7, 12 and 24 nm, respectively, is reported. It is shown that the viscosity/stress of a gelling system increases with time after gel initiation
Displaying 32051 - 32075 of 73929
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