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Displaying 43501 - 43525 of 74893

Statistical Uncertainty Analysis of CCEM-K2 Comparisions of Resistance Standards

June 1, 2002
Author(s)
Nien F. Zhang, N Sedransk, Dean G. Jarrett
Details of the statistical uncertainty analysis applied to key comparison CCEM-K2 are reported. Formulas were derived to determine the uncertainty of the combined difference between the measurements of multiple artifacts by an NMI and the corresponding

Statistical Uncertainty Analysis of CCEM-K2 Comparisons of Resistance Standards

June 1, 2002
Author(s)
Nien F. Zhang, N Sedransk, Dean G. Jarrett
Details of the statistical uncertainty analysis applied to key comparison CCEM-K2 are reported. Formulas were derived to determine the uncertainty of the combined difference between the measurements of multiple artifacts by an NMI and the corresponding

Structural Reliability Estimates and Database-Assisted Design for Wind

June 1, 2002
Author(s)
F Minciarelli, Fahim H. Sadek, Emil Simiu, Mircea Grigoriu
We propose a probabilistic methodology for developing improved estimates of extreme wind effects and load factors in standard provisions for wind loads. We obtained the following results: (1) the discrepancy between current estimates of safety indices for

Structural Study of Li 1+x-y Nb 1-x-3y Ti x+4y O 3 Solid Solutions

June 1, 2002
Author(s)
L Farber, Igor Levin, A Borisevich, I E. Grey, Robert S. Roth, P K. Davies
The structures of Lil+x-yNbl-,-3yTix+4yO3 solid solutions within the so-called M-phase field in the Li2O-Nb2O5-TiO2system were investigated using HRTEM and single crystal X-ray diffraction. The results demonstrated the phasefield is comprised of a

Structure and Properties of Silica Nanoclusters at High Temperatures

June 1, 2002
Author(s)
I V. Schweigert, K E. Lehtinen, Michael J. Carrier, Michael R. Zachariah
The properties of silica clusters at temperatures from 1500 to 2800 K are investigated using classical molecular dynamics simulations for particles containing up to 1152 atoms. We found that atoms in the cluster were arranged in a shell-like structure at

The Magic of Cryogenics

June 1, 2002
Author(s)
D P. Vigliotti, J B. Alcorn, B P. Marsh, N A. Neumeyer
The purpose of this presentation is to introduce teachers to a demonstration that exposes K-12 students to a variety of scientific areas through experiments using liquid nitrogen. This presentation demonstrates how changing the temperature of materials

The NIST Microforce Realization and Measurement Project

June 1, 2002
Author(s)
David B. Newell, Jon R. Pratt, John A. Kramar, Douglas T. Smith, Edwin R. Williams
The National Institute of Standards and Technology (NIST) has launched a five-year Microforce Realization and Measurement project focusing on the development of an instrument and laboratory capable of realizing and measuring the SI unit of force below

The NIST Microforce Realization and Measurement Project

June 1, 2002
Author(s)
David B. Newell, Jon R. Pratt, John A. Kramar, Douglas T. Smith, Edwin R. Williams
The National Institute of Standards and Technology (NIST) has launched a five-year Micro-force Realization and Measurement project focusing on the development of an instrument and laboratory capable of realizing and measuring the SI unit of force below

The Protein Data Bank (PDB)

June 1, 2002
Author(s)
H M. Berman, T Battistuz, Talapady N. Bhat, W Bluhm, P E. Bourne, K Burkhardt, L Iype, Sanjay Jain, P Fagan, J Marvin, D Padilla, Veerasamy Ravichandran, Barry I. Schneider, N Thanki, H Weissig, J Westbrook, C Zardecki
The Protein Data Bank (PDB) is the single worldwide repository of structural data of biological macromolecules. This paper describes the goals of the PDB, the systems in place for data deposition and access, how to obtain further information, and near-term

The Revision of Standard 62: What a Difference a Decade Makes

June 1, 2002
Author(s)
Andrew K. Persily
The American Society of heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) has been revising Standard 62,Ventilation for Acceptable Indoor Air Quality since 1991. The two primary motivations for this revision have been 1) to convert the

Thermodynamic Quantities for the Ionization Reactions of Buffers

June 1, 2002
Author(s)
Robert N. Goldberg, N Kishore, R M. Lennen
This review contains selected values of thermodynamic quantities for the aqueous ionization reactions of 63 buffers, many of which are used in biological research. Since the aim is to be able to predict values of the ionization constant at temperatures not

Understanding Part Fabrication Errors in Closed-Loop Machining Systems

June 1, 2002
Author(s)
Herbert T. Bandy, Lawrence A. Welsch
This paper presents an analysis of part fabrication errors (part dimension and form deviations) in closed-loop machining systems. Modeling methods are used to situate error components in the context of other error components to clarify the effects of error

Understanding the U.S. National Standards System

June 1, 2002
Author(s)
K J. Johnsen
This article, intended for publication in German in Germany, clarifies attributes of the U.S.standards system and its similarities and differences with European and international counterparts. In the United States, standardization is essentially a free

Unraveling the Symmetry of the Hole States Near the Fermi Level in the MgB 2 Superconductor

June 1, 2002
Author(s)
Y Zhu, A R. Moodenbaugh, G Schneider, J W. Davenport, T Vogt, Q Li, G Gu, Daniel A. Fischer, J Tafto
We use x-ray absorption spectroscopy (XAS) and electron energy loss spectroscopy (EELS) to study the near edge fine structure at the K-edge of boron in the superconductor M gB 2. We observe in XAS a peak of width 0.6 eV at the threshold of this K-edge

Using a High-Value Resistor in Single-Electron Counting Measurements

June 1, 2002
Author(s)
Randolph Elmquist, Neil M. Zimmerman, William Huber
An experiment using a high-value cryogenic resistor is proposed, with the aim of improving the experimental link between three quantum electrical standards. This technique is new in its approach and does not require feedback from either a voltage detector

Using a High-Value Resistor in Triangle Comparisons of Electrical Standards

June 1, 2002
Author(s)
Randolph Elmquist, Neil M. Zimmerman, William Huber
We propose an experiment with some advantages over other direct quantum metrology triangle comparisons. First, by using a cryogenic resistor that can be calibrated, the QHR standard needs to be used only for short periods. Second, the experiment does not

Vibrational Population Control in Liquid-Phase Metal Carbonyls

June 1, 2002
Author(s)
V D. Kleiman, Joseph S. Melinger, Edwin J. Heilweil
Broadband picosecond and femtosecond mid-infrared chirped-pulse excitation with broadband probe techniques are being explored at NIST using multi-element, mid-infrared focal plane array detectors. Ultrafast infrared chirped IR pulse generation, detection
Displaying 43501 - 43525 of 74893