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Displaying 626 - 650 of 2736

Comparison of CBED and ABF Atomic Imaging for GaN Polarity Determination

November 8, 2016
Author(s)
Alexana Roshko, Matthew D. Brubaker, Paul T. Blanchard, Kristine A. Bertness, Todd E. Harvey, Igor Levin, R.H. Geiss
A comparison of two electron microscopy techniques used to determine the polarity of GaN nanowires is presented. The techniques are convergent beam electron diffraction (CBED) in TEM mode and annular bright field (ABF) imaging in aberration corrected STEM

Calibration of Time-interleaved Errors in Real-time Digital Oscilloscopes

November 1, 2016
Author(s)
Jeffrey A. Jargon, Chihyun Cho, Joo-Gwang Lee, Paul D. Hale, Peter J. Jeavons, John B. Schlager, Andrew M. Dienstfrey
A novel method is proposed for the calibration of channel mismatch in a time-interleaved real- time digital oscilloscope (RTDO). A simple simultaneous equation is derived from the Fourier transform of the time-interleaved signals requiring only a transfer

An Overview of Atom-Based SI-Traceable Electric-Field Metrology

October 30, 2016
Author(s)
Joshua A. Gordon, Christopher L. Holloway, Matthew T. Simons
We present an overview of radio frequency (RF) electric-field measurements using Rydberg atoms. This technique exploits the rich resonance response of these atoms which can occur across a large frequency range from 1 GHz-500 GHz. This measurement utilizes

Gain Comparison of a 3D?Printed Horn and an Electroformed Horn

October 29, 2016
Author(s)
Michael H. Francis, David R. Novotny, Josh Gordon, Alexandra Curtin, Ronald C. Wittmann
The National Institute of Standards and Technology (NIST) has used the three‐antenna extrapolation method to determine the on‐axis gain of several antennas in the WR8 frequency band. One antenna is an electroformed μ=±1 probe with gain of about 9 dB. The

Thermodynamic Properties at Saturation Derived from Experimental Two-Phase Isochoric Heat Capacity of 1-Hexyl-3-methylimidazolium bis[trifluoromethyl)sulfonyl]imide

October 27, 2016
Author(s)
Joe W. Magee, N. G. Polikhronidi, Rabiyat G. Batyrova, I M. Abdulagatov, J. Wu
New measurements are reported for the isochoric heat capacity of the ionic liquid substance 1- hexyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C6mim][NTf2]). These measurements extend the ranges of our earlier study [N.G. Polikhronidi et al

Transmission Electron Microscope Calibration Methods for Critical Dimension Standards

October 13, 2016
Author(s)
Ndubuisi G. Orji, Ronald G. Dixson, Domingo I. Garcia-Gutierrez, Bunday Benjamin, M R. Bishop, Michael W. Cresswell, Richard A. Allen, John Allgair
One of the key challenges in critical dimension (CD) metrology is finding suitable dimensional calibration standards. The transmission electron microscope (TEM), which produces lattice-resolved images having scale traceability to the SI (International

Cyber-physical Systems Engineering for Manufacturing

October 7, 2016
Author(s)
Allison Barnard Feeney, Simon P. Frechette, Vijay Srinivasan
There is a convergence of interests in cyber-physical systems, systems engineering, and manufacturing innovation in the United States. The U.S. National Institute of Standards and Technology (NIST) has undertaken research programs in smart manufacturing

Inertial Measurement Unit for On-Machine Diagnostics of Machine Tool Linear Axes

October 7, 2016
Author(s)
Gregory W. Vogl, Alkan Donmez, Andreas Archenti, Brian A. Weiss
Machine tools degrade during operations, yet knowledge of degradation is elusive; accurately detecting degradation of machines' components such as linear axes is typically a manual and time-consuming process. Thus, manufacturers need automated, efficient

Measurement of powder bed density in powder bed fusion additive manufacturing processes

October 5, 2016
Author(s)
Gregor Jacob, M A. Donmez, Shawn P. Moylan, John A. Slotwinski
There are many factors influencing the additive manufacturing (AM) processes resulting in high degree of variation in process outcomes. Therefore, quantifying these factors and their correlations to the process outcomes are important challenges to overcome

The rheo-Raman microscope: Simultaneous chemical, conformational, mechanical, and microstructural measures of soft materials

October 4, 2016
Author(s)
Anthony P. Kotula, Matthew Meyer, Francesca De Vito, Jan Plog, Angela R. Hight Walker, Kalman D. Migler
We describe the design and demonstrate performance of an instrument capable of simultaneous Raman spectroscopy, rheology, and optical microscopy of materials. The instrument couples a Raman microscope with a rotational rheometer through an optically

THE NIST MAGNETIC SUSPENSION MASS COMPARATOR: A LOOK AT AUTOMATION

September 29, 2016
Author(s)
Corey A. Stambaugh, Edward C. Mulhern
The magnetic suspension mass comparator at NIST is a fully automated mass comparator with the unique feature that it is able to directly compare a mass in vacuum to one in air. The technique is realized by coupling a weighing pan located in air to a mass

Bridging classical and quantum mechanics

September 28, 2016
Author(s)
Darine El Haddad, Frank C. Seifert, Leon S. Chao, Shisong Lee, David B. Newell, Jon R. Pratt, Carl J. Williams, Stephan Schlamminger
Using a watt balance and a frequency comb, a mass-energy equivalence is derived. The watt balance compares mechanical power measured in terms of the meter, the second, and the kilogram to electrical power measured in terms of the volt and the ohm. A direct
Displaying 626 - 650 of 2736
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