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Once is enough in radiometric calibrations
No full textThe successful development of an Optical Technology Division quality system for optical radiation measurement services has provided the opportunity to reconsider the existing calibration procedures to improve quality and reduce costs. We have instituted procedures in our calibration programs to eliminate uninformative repetitive measurements by concentrating our efforts on controlling and understanding the measurement process. The first program in our calibration services to undergo these revisions is described in this paper
Biophotonic tools in cell and tissue diagnostics
No full textIn order to maintain the rapid advance of biophotonics in the U.S. and enhance our competitiveness worldwide, key measurement tools must be in place. As part of a wide-reaching effort to improve the U.S. technology base, the National Institute of Standards and Technology sponsored a workshop titled "Biophotonic tools for cell and tissue diagnostics." The workshop focused on diagnostic techniques involving the interaction between biological systems and photons. Through invited presentations by industry representatives and panel discussion, near- and far-term measurement needs were evaluated. As a result of this workshop, this document has been prepared on the measurement tools needed for biophotonic cell and tissue diagnostics. This will become a part of the larger measurement road-mapping effort to be presented to the Nation as an assessment of the U.S. Measurement System. The information will be used to highlight measurement needs to the community and to facilitate solutions
List of Names mentioned in oral history interview of Barry Taylor, October 31, 2007 / with David Lide, Norman Belecki, Edwin Williams, and Ralph Hudson.
No full textBarry Taylor recalls his career at NIST from June 1970 untill his retirement in March 2001
(Transcript) Oral history interview of Barry Taylor, October 31, 2007 / with David Lide, Norman Belecki, Edwin Williams, and Ralph Hudson.
No full textBarry Taylor recalls his career at NIST from June 1970 untill his retirement in March 2001
Flow control through the use of topography
No full textIn this work, optimal shaft shapes for flow in the annular space between a rotating shaft with axially-periodic radius and a fixed coaxial outer circular cylinder, are investigated. Axisymmetric steady flows in this geometry are determined by solving the full Navier-Stokes equations in the actual domain. A measure of the flow field, a weighted convex combination of the volume averaged square of the L-2-norm of the velocity and vorticity vectors, is employed. It has been demonstrated that boundary shape can be used to influence the characteristics of the flow field, such as its velocity component distribution, kinetic energy, or even vorticity. This ability to influence flow fields through boundary shape may be employed to improve microfluidic mixing or, possibly, to minimize shear in biological applications
Microwave power absorption in low-reflectance, complex, lossy transmission lines
No full textSimple sets of equations have been derived to describe the absorption of microwave power in three-region, lossy transmission lines in terms of S-parameter reflection and transmission amplitudes. Each region was assumed to be homogeneous with discontinuities at the region boundaries. Different sets of equations were derived to describe different assumptions about the amplitudes of the reflection coefficients at the different boundaries. These equations, which are useful when interference effects due to multiple reflections are small, were used to analyze S-parameter measurements on a transmission line that had a microfluidic channel in its middle region. The channel was empty for one set of measurements and filled with water for a second set of measurements. Most of the reflection assumptions considered here produced similar results for the fraction of the applied microwave power that was absorbed by a water-filled microchannel. This shows that the absorbed power is relatively insensitive to the reflection details as long as energy is conserved in the analysis. Another important result of this work is that the difference between the power absorbed in a water-filled channel and the power absorbed in the same empty channel can be a poor predictor of the power absorbed in the water in the presence of competing absorption processes such as absorption by the transmission-line metal
Modeling of photochemical reactions in a focused laser beam
No full textFluorescent materials play a prominent role in the qualitative and quantitative measurement of scientific phenomena of importance in biotechnology and biomedical applications. Photodegradation of fluorophores is a process that determines the accuracy and sensitivity of such measurements. This is the motivation for developing methods for accurately measuring fluorophore photodegradation rates. Recently, illumination consisting of short pulses has been used to examine the decay of photochemical reaction products. However, the time resolved measurements are difficult to interpret since the photodegradation process usually involves multiple time scales. The frequency domain measurement technique discussed here looks at the frequency response of a fluorescent sample to a frequency modulated illuminating light. The photodegradation rate is obtained by interpreting the frequency domain measurements in terms of traditional impedance concepts. In the measurements described in this paper, a focused laser beam is used to illuminate a sample of slowly flowing fluorescent solution. The laser beam is assumed to have a Gaussian power distribution hence illumination is spatially non-uniform in the region of interest. The photochemical reaction rates depend on power, so they will also vary with the position in the beam. However in the case of photodegradation of fluorophores, the measurement of the resulting decrease in fluorescence is given in terms of the radiation emitted from the entire illuminated region. In this work we present a mathematical description of the time evolution of the fluorescence response integrated over a non-uniformly illuminated domain. As a result of our analysis, an experimentally accessible and tractable mathematical model Eq. (19) and Eq. (30) is obtained from a more fundamental description given by Eq. (4) and Eq. (5). The model is used to create a functional form for fitting experimental measurements from a lock-in amplifier
Comparison between NIST and AF laser energy standards using high power lasers
No full textWe report the results of a high-energy laser calorimeter comparison conducted by the National Institute of Standards and Technology (NIST), Boulder, Colorado and the U.S. Air Force Primary Standards laboratory (AFPSL), Heath, Ohio. A laser power meter, used as a transfer standard, was calibrated at each laboratory, sequentially, and the measurement results were compared. These measurements were performed at a nominal power of 800 W and a wavelength of 10.6 micro-m using CO2 lasers. Excellent measurement agreement (1.02 %) was demonstrated, which was well within each of the expanded uncertainties from the two laboratories involved in this comparison
(Audio Part 2 of 3) Oral history interview of Barry Taylor, October 31, 2007 / with David Lide, Norman Belecki, Edwin Williams, and Ralph Hudson.
No full textBarry Taylor recalls his career at NIST from June 1970 untill his retirement in March 2001
David A. Didion
No full textDAVID A. DIDION
Inducted: 2007
Citation:
For enhancing U.S. competitiveness and public benefit by visionary and timely response to the fundamental research needs of the HVAC industry for energy conservation and for the development of refrigerants that are compatible with the environment.
Tenure: 1960-1962 & 1971-2002
Birth: 1937, Pittsburgh, Pennsylvania
Education:
Catholic University, BME (Mechanical Engineering), 1959
Catholic University, MME (Mechanical Engineering), 1962
Catholic University, D.Eng (Mechanical Engineering), 1972
Positions held:
Engineer, Building Research Division, 1960-1962
Research Engineer, Building Research Division and Center for Building Technology (CBT), 1971-1974
Group Leader, CBT and Building and Fire Research Laboratory, 1974-1995
NIST Fellow, Building and Fire Research Laboratory, 1995-2002
Honors:
NIST Engineer of Year, National Society of Professional Engineers (1981)
U.S. Department of Commerce Silver Medal (1981) and Gold Medal (1987)
NIST Applied Research Award (1987)
NIST Edward Uhler Condon Award (1988)
NIST William P. Slichter Award (1995)
Outstanding Services to the Industry Award, Air Conditioning and Refrigeration Institute (1995)
1st Gustav Lorentzen Prize, International Institute of Refrigeration (1999)
Hall Gold Medal, U.K. Institute of Refrigeration (2001)
Memberships:
Fellow, American Society of Heating, Refrigerating, and Air Conditioning Engineers
Fellow, American Society of Mechanical Engineers
International Institute of Refrigeration
Publications:
More than 90 publications including:
Didion, D., Garvin, D., Snell, J., “Relevance of the 2nd Law of Thermodynamics to Energy Conservation”
NBS Technical Note 1115 (1980).
McLinden, M. and Didion, D., “The Quest for Alternatives” ASHRAE Journal (December, 1987).
Domanski, P., Kim, M. S., and Didion, D., NIST Database 49 Cycle-D (2000) and NIST Database 73 Refleak (2007).
Didion, D., “The Role of Refrigerant Mixtures”, IIF/IIR Bulletin, Tome LXXIV No.3 (1994).
Didion, D., “The Influence of the Thermophysical Fluid Properties of the New Ozone-safe Refrigerants on
Performance”, Int. J. of Applied Thermodynamics, Vol. 2, No.1 pp 19-35 (1999).
Didion, D., “The Role MicroElectroMechanical Systems has in the Refrigeration Industry”, U.K. Inst. of
Refrigeration, Special Paper, 2002-3 Session