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A systematic approach for multidimensional, closed-form analytic modeling: Minority electron mobilities in Ga1-xAlxAs heterostructures
No full textA significant, practical challenge, which arises in developing computationally efficient physical models for use in computer simulations of microelectronic and optoelectronic devices (for example, transistors in digital cellular phones and lasers in optical networks, respectively), is to represent vast amounts of numerical data for transport properties in two or more dimensions in terms of closed form analytic expressions. In this paper, we present a general methodology to achieve the above goal for a class of numerical data in a bounded two-dimensional space. We then apply this methodology to obtain a closed-form analytic expression for the minority electron mobilities at 300 K in p-type Ga1-xAlxAs as functions of the acceptor density N-A between 10(16) cm(-3) and 10(20) cm(-3) and the mole fraction of AlAs x between 0.0 and 0.3. This methodology and its associated principles, strategies, regression analyses, and graphics are expected to be applicable to other problems beyond the specific case of minority mobilities addressed in this paper
Massic activity ratios of the NBS/NIST tritiated-water standards issued between 1954 and 1999
No full textAs part of the preparation and calibration of three new National Institute of Standards and Technology (NIST) tritiated-water radioactivity Standard Reference Materials (SRMs), the massic-activity (activity of the sample divided by the mass of the sample) ratios of all of the available NBS/ NIST tritiated-water SRMs issued between 1954 and 1999 were measured using liquid-scintillation (LS) counting. Four of the tritiated-water standards (SRMs 4361, 4926B, 4927C, and 4927D) were not available for measurement. All of the other tritiated-water standards (SRMs 4361B, 4361C, 4926, 4926C, 4926D, 4926E, 4927, 4927B, 4927E, and 4927F) were available, having been stored in flame-sealed glass ampoules. Where possible, massic-activity ratios measured by liquid-scintillation counting are compared with massic-activity ratios calculated from gravimetric dilution factors. The agreement is well within the stated uncertainties. For two of the tritiated-water standards that were not available for measurement (SRMs 4361 and 4926B), massic-activity ratios calculated from gravimetric dilution factors are available
Numerical evaluation of diffraction integrals
No full textThis paper describes a simple numerical integration method for diffraction integrals which is based on elementary geometrical considerations of the manner in which different portions of the incident wavefront contribute to the diffracted field. The method is applicable in a wide range of cases as the assumptions regarding the type of integral are minimal, and the results are accurate even when the wavefront is divided into only a relatively small number of summation elements. Higher accuracies can be achieved by increasing the number of summation elements and/or incorporating Simpson's rule into the basic integration formula. The use of the method is illustrated by numerical examples based on Fresnel's diffraction integrals for circular apertures and apertures bounded by infinite straight lines (slits, half planes). In the latter cases, the numerical integration formula is reduced to a simple recursion formula, so that there is no need to perform repetitive summations for every point of the diffraction profile
President Bill Clinton and Secretary of Commerce William M. Daley with the Malcolm Baldrige National Quality Award winners
No full textFront row: National Quality Award winners with President Bill Clinton and Secretary of Commerce William Daley. Back row (center, left) Letitia Baldrige. Various NIST staff in the group: Barbara Silcox and Harry Hertz (Baldrige Program Office); Karen Brown, Acting NIST Director. This image is part of the Malcolm Baldrige Portrait File collection. The Malcolm Baldrige File collection contains photographs of the annual national award given by the President of the United States for industrial excellence. The award was named for Secretary of Commerce Malcolm Baldrige who died in 1987. The collection also includes photographs of the Malcolm 'Mac' Baldrige National Oceanic and Atmospheric Administration (NOAA) Ship
President Bill Clinton delivers an address at the Malcolm Baldrige National Quality Award Ceremony
No full textThis image is part of the Malcolm Baldrige Portrait File collection. The Malcolm Baldrige File collection contains photographs of the annual national award given by the President of the United States for industrial excellence. The award was named for Secretary of Commerce Malcolm Baldrige who died in 1987. The collection also includes photographs of the Malcolm 'Mac' Baldrige National Oceanic and Atmospheric Administration (NOAA) Ship
Marilyn E. Jacox
No full textMARILYN E. JACOX
NBS/NIST: 1962 ‑ 1995
Birth: April 26, 1929, Utica, New York
Education:
Syracuse University: BA (Chemistry), 1951; ScD (Hon.), 1993
Cornell University, PhD (Physical Chemistry), 1956
Principal fields:
Molecular spectroscopy; photochemistry
Positions held at NBS/NIST:
Research Chemist
Chief, Photochemistry Section
Chief, Environmental Chemical Processes Section
Fellow
Post‑retirement: Scientist Emeritus
Honors:
U.S. Department of Commerce Gold Medal, 1970
Washington Academy of Sciences Award in Physical Sciences, 1968
Federal Women's Award, 1973
NBS Stratton Award, 1973
Coblentz Society Lippincott Award, 1989
Chemical Society of Washington Hillebrand Award, 1990
Interagency Committee of Women in Science and Engineering WISE Lifetime Achievement Award, 1991
Elected to Sigma Xi
Memberships:
American Physical Society (Fellow)
American Association for the Advancement of Science (Fellow)
Inter‑American Photochemical Society (Executive Committee)
Executive Women in Government (Secretary; Vice‑chairman)
American Chemical Society
Washington Academy of Sciences (Fellow)
Publications:
Authored over 155 scientific papers on the chemistry and molecular spectroscopy of free radicals and molecular ions, and one book of spectroscopic tables
Treasure of the Past: IV. The standard-cell comparator. A specialized potentiometer
No full textThe standard cell plays a very important role in the maintenance of the electrical units and in correlating the units of the various national laboratories. Modern standard cells have obtained such a high degree of reproducibility and permanence as to warrant the use of apparatus of the utmost precision and reliability in their intercomparison. The paper describes a new potentiometer developed especially for this purpose. Although it actually measures the small difference between the known emf of a reference cell and that of the cell under test, it contains a simple mechanical computing feature which automatically adds this small difference algebraically to the emf of the reference cell and thereby indicates directly the value of the emf under measurement. The design of the instrument is such that no readjustment of its coils will be required when the impending changes in the ohm and the volt are accomplished. The new instrument has been given the distinctive name, ""standard-cell comparator""