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Displaying 24201 - 24225 of 73985

New Improved System for WWVB Broadcast

November 14, 2011
Author(s)
John P. Lowe, Matthew J. Deutch, Glenn K. Nelson, Douglas D. Sutton, William C. Yates, Peder Hansen, Oren Eliezer, Tom Jung, Stephen Morrison, Yingsi Liang, Dinesh Rajan, Sidharth Balasubramanian, Arun Ramasami, Waleed Khalil
The WWVB broadcast of the time-code signal has not undergone major changes in its communications protocol and modulation scheme since its introduction in 1963. Its amplitude-modulation (AM) and pulse-width based representations of its digital symbols were

Synchronizing Computer Clocks by the Use of Kalman Filters

November 14, 2011
Author(s)
Judah Levine
The National Institute of Standards and Technology (NIST) currently operates 35 public network time servers that are located at many different sites in the United States. The servers provide time messages over the public Internet in a number of different

Impact Testing - Yesterday and Today

November 13, 2011
Author(s)
Enrico Lucon, Christopher N. McCowan
The Charpy impact test is a standardized high strain rate mechanical test which determines the amount of energy absorbed by a material during impact fracture. This test is widely applied in industry, since it is easy to prepare and conduct, and results can

Capacitive readout technique for studies of dissipation in GaN nanowire mechanical resonators

November 11, 2011
Author(s)
Kristine A. Bertness, Joshua R. Montague, Norman A. Sanford, Victor Bright, Charles T. Rogers
A variable-temperature, homodyne reflectometry measurement technique for detecting nanoscale mechanical motion has recently been developed. We have extended this technique to make the first all-electrical measurements of an ensemble of as-grown, c-axis

Characterization of (1-3,1-6)-b-D-Glucan Side Chain Structure Provides the Basis for a New Model of Fungal Cell Wall Rigidity and Flexibility

November 11, 2011
Author(s)
Daniel W. Bearden, Douglas W. Lowman, Lara J. West, Michael F. Wempe, Trevor D. Power, Harry E. Ensley, Ken Haynes, David L. Williams, Michael D. Kruppa
Glucan is a (1-3)-β-linked glucose polymer with (1-6)-β-linked side chains and a major component of fungal cell walls. Glucans provide structural integrity to the fungal cell wall. The nature of the (1-6)-β-linked side chain structure of fungal (1-3,1-6)-β

Quantum-based Voltage Waveform Synthesis

November 11, 2011
Author(s)
Samuel P. Benz
More than a decade of research and development was required to practically exploit the quantum behavior of superconducting Josephson junctions for ac applications. Sine waves and arbitrary waveforms had to be synthesized with sufficiently large voltage

In situ monitoring of enzyme-catalyzed (co)polymerizations by Raman spectroscopy

November 10, 2011
Author(s)
Matthew T. Hunley, Atul Bhangale, Santanu S. Kundu, Peter M. Johnson, Michael S. Waters, Richard Gross, Kathryn Beers
In situ, fiber optic-based Raman spectroscopy provided real time monitoring of enzyme-catalyzed ring-opening homo- and copolymerizations of ε-caprolactone (ε-CL) and δ-valerolactone (δ-VL). A custom designed reactor equipped with in situ fiber optic probe

Reliability Testing of Advanced Interconnect Materials

November 10, 2011
Author(s)
Robert R. Keller, Mark C. Strus, Ann C. Chiaramonti Debay, David T. Read, Younglae Kim, Yung J. Jung
We describe the development of electrical test methods to evaluate damage that determines reliability in advanced, small-scale conductors, including damascene copper and aligned carbon nanotube networks. Rapid thermal cycling induced during high-current AC

Uncertainties of Measures in Speaker Recognition Evaluation

November 10, 2011
Author(s)
Jin Chu Wu, Alvin F. Martin, Craig S. Greenberg, Raghu N. Kacker
The National Institute of Standards and Technology (NIST) Speaker Recognition Evaluations (SRE) are an ongoing series of projects conducted by NIST. In the NIST SRE, speaker detection performance is measured using a detection cost function, which is

Response of Acoustic Phonons to Charge and Orbital order in the 50% Doped Bilayer Manganite LaSr 2 Mn 2 O 7 .

November 9, 2011
Author(s)
F. Weber, S. Rosenkranz, J.-P. Castellan, R. Osborn, H. Zheng, J. F. Mitchell, Y. Chen, Song Xue Chi, Jeffrey W. Lynn, D. Reznik
We report an inelastic neutron scattering study of acoustic phonons in the charge and orbitally ordered bilayer manganite LaSr 2. For excitation energies less than 15 meV, we observe an abrupt increase (decrease) of the phonon energies (linewidths) of a

Structure and Properties of Polymer Electrolyte Membranes Containing Phosphonic Acids for Anhydrous Fuel Cells

November 9, 2011
Author(s)
Kirt A. Page, Christopher L. Soles, Huagen H. Peng, Do Y. Yoon, Sung-Il Lee, Myeongsoo Song, Kyung-Hwan Yoon, Wolfgang Meyer
Recently, water-free, proton conducting, polymer electrolytes are attracting attention due to their possible application as fuel cell membranes at intermediate temperatures (100 ºC to 200 ºC). Phosphonic acid groups are considered feasible anhydrous proton

Site-Specific CO 2 Adsorption and Zero Thermal Expansion in an Anisotropic Pore Network

November 8, 2011
Author(s)
Wendy Queen, Craig M. Brown, David K. Britt, Matthew R. Hudson, Omar M. Yaghi
Detailed neutron powder diffraction (NPD) experiments were carried out on the bare and CO 2 adsorbed Mg-MOF 74. While low-temperature data revealed two CO 2 adsorption sites and multiple changes in the framework as a function of CO 2 loading, room

Electron Counting Capacitance Standard with an improved five-junction R-pump

November 7, 2011
Author(s)
Benedetta Camarota, Hansjoerg Scherer, Sergey Lotkhov, Gerd-Dietmar Willenberg, Franz Josef Ahlers, Mark W. Keller
The Electron Counting Capacitance Standard currently pursued at PTB, aims at the closure of the Quantum Metrological Triangle with a final precision of a few parts in 10 7. This paper reports the considerable progress recently achieved with a new
Displaying 24201 - 24225 of 73985
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