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Displaying 50301 - 50325 of 74165

A New Determination of the Newtonian Constant of Gravity Using the Free Fall Method

June 1, 1999
Author(s)
J. Schwarz, D S. Robertson, T M. Niebauer, J E. Faller
We report on a recent determination of the Newtonian constant of gravity, G, using a new free fall method. This method uses a freely falling test object to sense the gravitational field of a ring-shaped mass placed alternately above and below the drop

A primary pressure standard at 100 kPa

June 1, 1999
Author(s)
James W. Schmidt, Y Q. Cen, Robert G. Driver, Walter J. Bowers Jr., J C. Houck, S A. Tison, Charles D. Ehrlich
Primary pressure standards in the atmospheric pressure range are often established using mercury manometers. To a lesser extent controlled-clearance dead-weight testers in which one component (normally the piston) has been dimensionally measured have also

A Queueing Model of a Spread Spectrum Multiple Access

June 1, 1999
Author(s)
Vladimir V. Marbukh, Nader Moayeri
We propose a queueing model of the reverse link from mobiles to the base station in a single cell of a cellular DS-CDMA system. Approximation of independent queues leads to a non-linear fixed point equation that describes globally or locally stable system

Acid-Assisted Consolidation of Powder Compacts: Cold-Welding or Cold Sintering

June 1, 1999
Author(s)
M P. Dariel, M Ratzker, F Eichmiller
Silver powder that has been treated in dilute fluoroboric acid solution and compacted at room temperature displays surprisingly elevated flexural and even tensile strength. The density and mechanical strength values increase with increasing compaction

An Overview of the Development of Technical Infrastructure in the Asia-Pacific Region: The Work of the Asia-Pacific Economic Cooperation (APEC) Sub-Committee in Standards and Conformance (SCSC) and the Specialist Regional Body (SRBS)

June 1, 1999
Author(s)
C R. DeVaux
The development and maintenance of an economy's standards and conformance technical infrastructure is critical to its economic health. By increasing the competence of its measurement and testing capabilities, in particular, an economy can provide

Analysis of Current Flow in Mono-Crystalline Electrical Linewidth Structures

June 1, 1999
Author(s)
S Smith, I. A. Lindsay, Anthony Walton, Michael W. Cresswell, Loren W. Linholm, Richard A. Allen, M. Fallon, Alan Gundlach
The current flow in lightly doped mono-crystalline silicon structures designed for use as low cost secondary reference linewidth standards is investigated. It is demonstrated that surface charge can have a significant effect upon the measurements of

Analysis of Residual Stress State in Thermal Barrier Coatings

June 1, 1999
Author(s)
Tze-Jer Chuang, Lin-Sien H. Lum
To enhance thermal efficiency of a system in high temperature structural applications, thermal barrier coatings (TBC) are often applied on the metallic substrate to protect the component from deterioration while increasing the operating temperature of the

Annealing Effects on the Coercivity of SmCo 5 Nanoparticles

June 1, 1999
Author(s)
K Chowdary, A K. Giri, K Pellerin, S. A. Majetich, J H. Scott
The enhanced coercivity of ball milled nanoparticles of SmCo 5 has been attributed to the reduced particle size, but the milling process introduces additional strain which can also affect the coercivity. Here the effects of size and strain are decoupled

Assessing Algorithms as Computational Models for Human Face Recognition

June 1, 1999
Author(s)
P J. Phillips, Alice J. O'Toole, Y Cheng, B Ross, H A. Wild
We assessed the qualitative accord between several automatic face recognition algorithms and human perceivers. By comparing model- and human-generated measures of the similarity between pairs of faces, we were able to evaluate the suitability of the

Assessment Error Sources in Rockwell Hardness Measurements

June 1, 1999
Author(s)
Walter S. Liggett Jr, Samuel Low, David J. Pitchure, Jun-Feng Song
In the use of hardness test blocks, the uncertainty due to block non-uniformity can be reduced if one is willing to make measurements at specified locations on the blocks. Statistical methods for achieving this reduction are explained in this paper. The

Behavior of a Charged Two-Level Fluctuator in Al-AlO x -Al Single-Electron Transistor

June 1, 1999
Author(s)
M. Kenyon, J. L. Cobb, A. Amar, D. Song, C. J. Lobb, Neil M. Zimmerman, F. C. Wellstood
We have studied the behavior of a charged two-level fluctuator in an Al-AlO x -Al single-electron transistor (SET) in the normal state over a temperature range from 85 mK to 3K. The fluctuator caused the SET's island charge to shift by δQ0= 0.11 0.025 e

Calibration of Thin-Film Thermocouples on Silicon Wafers

June 1, 1999
Author(s)
Kenneth G. Kreider, Dean C. Ripple, D P. DeWitt
Thin-film thermocouples (TFTCs) can be fabricated from a much broader range of electrical conductors than wire thermocouples, but even with the same composition as the wire thermocouple, the TFTCs may have different thermoelectric coefficients. Also, the

Collisions of Cold Magnesium Atoms in a Weak Laser Field

June 1, 1999
Author(s)
M Machholm, Paul S. Julienne, K A. Suominen
We calculate the laser-induced collisional loss of laser-cooled and trapped magnesium atoms for detunings up to 30 atomic linewidths to the red of 1S O -> 1P 1 cooling transition. Magnesium is an excellent test case for theoretical studies, because it can

Coplanar Transmission Lines with Meandering Center Conductors in Y-Ba-Cu-O/Au Bilayers

June 1, 1999
Author(s)
C Weber, Ronald H. Ono, James Booth, Leila R. Vale, Samuel Benz, A. M. Klushin, H. Kohlstedt, R. Semerad
We have investigated both conventional and meandering coplanar microwave transmission lines patterned in Y-Ba-Cu-O/Au bilayers on yttria-stablized zirconia and sapphire substrates. Within the meandering waveguides, the gentre conductor was deformed from a
Displaying 50301 - 50325 of 74165
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