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Displaying 1151 - 1175 of 2606

High-resolution neutron radiography of through-plane liquid water distribution in polymer electrolyte membrane and gas diffusion layer

August 14, 2012
Author(s)
Daniel S. Hussey, David L. Jacobson, Richard Fu, Ugur Pasaogullari, Takeshi Shiomi, Yuichiro Tabuchi
We re-investigate our previously studied water transport phenomena under nonisothermal conditions by measuring the through-plane liquid water distribution across PEFC components with the state-of-the-art high-resolution neutron radiography. A corrective

Characterization of Surface Accumulation and Release of Nanosilica During Irradiation of Polymer Nanocomposites with Ultraviolet Light

August 12, 2012
Author(s)
Tinh Nguyen, Bastien T. Pellegrin, Coralie Bernard, Savelas A. Rabb, Paul E. Stutzman, Justin M. Gorham, Xiaohong Gu, Lee L. Yu, Joannie W. Chin
Nanofillers are increasingly used for enhancing multiple properties of polymeric materials in many applications. However, polymers are susceptible to photodegradation by solar ultraviolet (UV) radiation Therefore, nanofillers in a polymer nanocomposite

Thermogravimetric Analysis with a Heated Quartz Crystal Microbalance

August 11, 2012
Author(s)
Ward L. Johnson, Elisabeth Mansfield
Thermogravimetric analysis with an SC-cut quartz crystal microbalance (QCM) were demonstrated at temperatures in the range from 20 C to 450 C. A measurement system was built around a crystal sensor head that was mounted in a small tube furnace. Changes in

Information Retrieval on the Blogosphere

July 30, 2012
Author(s)
Ian M. Soboroff, Rodrygo Santos, Craig Macdonald, Richard McCreadie, Iadh Ounis
Blogs have recently emerged as a new open, rapidly evolving and reac- tive publishing medium on the Web. Rather than managed by a central entity, the content on the blogosphere—the collection of all blogs on the Web—is produced by millions of independent

Information Required for Dimensional Measurement

July 27, 2012
Author(s)
John A. Horst, Curtis Brown, Robert Brown, Larry Maggiano, K Summerhays, Thomas R. Kramer
Much work has been done by standards organizations to model dimensional measurement information in digital formats, but the work done has revealed that standard digital formats from upstream processes are currently insufficient to enable the automatic

High-speed thermo-microscope for imaging thermal desorption phenomena

July 25, 2012
Author(s)
Matthew E. Staymates, John G. Gillen
In this work, we describe a new imaging system, called a thermo-microscope, that can be used to visualize atmospheric pressure thermal desorption phenomena at high heating rates and frame rates. The system consists of a zoom lens coupled to a high-speed

A New Measure in Cell Image Segmentation Data Analysis

July 24, 2012
Author(s)
Jin Chu Wu, Michael W. Halter, Raghu N. Kacker, John T. Elliott
Cell image segmentation (CIS) is critical for quantitative imaging in cytometric analyses. The data derived after segmentation can be used to infer cellular function. To evaluate CIS algorithms, first for dealing with comparisons of single cells treated as

Data Dependency on Measurement Uncertainties in Speaker Recognition Evaluation

July 11, 2012
Author(s)
Jin Chu Wu, Alvin F. Martin, Craig S. Greenberg, Raghu N. Kacker
The National Institute of Standards and Technology conducts an ongoing series of Speaker Recognition Evaluations (SRE). Speaker detection performance is measured using a detection cost function defined as a weighted sum of the probabilities of type I and

Room Temperature Acoustic Transducers for High-Temperature Thermometry

July 9, 2012
Author(s)
Dean C. Ripple, William E. Murdock, Gregory F. Strouse, Keith A. Gillis, Michael R. Moldover
We have successfully conducted highly-accurate, primary acoustic thermometry at 600 K using a sound source and a sound detector at room temperature. We describe the source, the detector, and the ducts that connected them to our cavity resonator. This

Displacement Sensor for Detecting Sub-micrometer Motion

July 6, 2012
Author(s)
Svetlana Avramov-Zamurovic1, Jae M. Yoo, Nicholas Dagalakis, Rae Duk Lee
This paper describes the design of a nano displacement sensor that detects the presence of a moving platform by using fringing electric field. Its electrodes are commercially prefabricated Teflon insulated wires. This solution provides for excellent

Traceability of high-speed electrical waveforms at NIST, NPL, and PTB

July 6, 2012
Author(s)
Paul D. Hale, Dylan F. Williams, Andrew M. Dienstfrey, Chih-Ming Wang, Jeffrey A. Jargon, David Humphreys, Matthew Harper, Heiko Fuser, Mark Bieler
Instruments for measuring high-speed waveforms typically require calibration to obtain accurate results. The national metrology institutes of the United States of America, the United Kingdom, and Germany offer measurement services based on electro-optic

The Permanent Magnet System for NIST-4

July 2, 2012
Author(s)
Stephan Schlamminger
At the National Institute of Standards and Technology a new watt balance, NIST-4, is currently being designed. This apparatus will be used to realize the base unit of mass after the redefinition of the SI has taken effect. As a realization device, NIST-4

A Digital-to-Analog Converter with a Voltage Standard Reference

July 1, 2012
Author(s)
Alain Rufenacht, Charles J. Burroughs, Samuel Benz, Paul Dresselhaus
Commercially available 20-bit digital to analog converters (DACs) have the potential to impact the field of low frequency voltage metrology. We measured a linearity of ±6 µV (±0.6 µV/V full scale) over the 10 V range for such a DAC with a Zener voltage

A Direct Comparison System for Power Calibration up to 67 GHz*

July 1, 2012
Author(s)
Thomas M. Wallis, Thomas P. Crowley, Denis X. LeGolvan, Ronald A. Ginley
A direct comparison system for calibration of power sensors with 1.85 mm precision coaxial connectors up to 67 GHz has been developed. The comparison is implemented in two frequency bands. Between 10 MHz and 50 GHz, power sensors with 2.4 mm coaxial

Calibration Techniques for Scanning Microwave Microscopy

July 1, 2012
Author(s)
Thomas M. Wallis, Atif A. Imtiaz, Alexandra Curtin, Pavel Kabos, H. P. Huber, Joseph J. Kopanski, F. Kienberger
Two techniques are described for calibrating a scanning microwave microscope (SMM). The first technique enables spatially-resolved absolute capacitance measurements on the attofarad-to-femtofarad scale. The second technique enables profiling or dopant

Flat frequency response in the electronic measurement of the Boltzmann constant

July 1, 2012
Author(s)
Jifeng Qu, Samuel Benz, Yang Fu, Jianqiang Zhang, Horst Rogalla, Alessio Pollarolo
A new quantum voltage calibrated Johnson noise thermometer (JNT) was developed at NIM to demonstrate the electrical approach that determines the Boltzmann constant k by comparing electrical and thermal noise power. A measurement with integration period of
Displaying 1151 - 1175 of 2606