14,018 research outputs found

    User's guide for atmospheric carbon monoxide transport model

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    In the winter months of Fairbanks, Alaska, a highly stable air temperature inversion creates high levels of carbon monoxide (CO) concentrations. As an aid to understanding this problem, a CO transport computer model has been created which provides a useful tool when used in conjunction with other measurement and analytic studies of traffic, meteorology, emissions control, zoning, and parking management. The model is completely documented and illustrated with several examples. Named ACOSP (Atmospheric CO Simulation Program), it predicts expected CO concentrations within a specific geographic area for a defined set of CO sources. At the present time, the model is programmed to consider automobile emissions as the major CO source and may include estimates of stationary sources. The model is coded for computer solution in the FORTRAN programming language and uses the finite-element method of numerical solution of the basic convective-diffusion equations. Although it has a potential for real-time analysis and control, at the present time the model will be most valuable for investigating and understanding the physical processes which are responsible for high CO levels and for testing remedial control measures at high speed and low cost

    Operational applications of NOAA-VHRR imagery in Alaska

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    Near-real time operational applications of NOAA satellite enhanced thermal infrared imagery to snow monitoring for river flood forecasts, and a photographic overlay technique of imagery to enhance snowcover are presented. Ground truth comparisons show a thermal accuracy of approximately + or - 1 C for detection of surface radiative temperatures. The application of NOAA imagery to flood mapping is also presented

    Break-up characteristics of the Chena River watershed, central Alaska

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    The author has identified the following significant results. The snow melt for a small watershed (5130 sq km) in Central Alaska was successfully monitored with ERTS-1 imagery. Aerial photography was used as supporting data for periods without satellite coverage. Comparison both with actual measurements and with a computer model showed good agreement

    Importance of Baryon-Baryon Coupling in Hypernuclei

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    The ΛN−ΣN\Lambda N - \Sigma N coupling in Λ\Lambda--hypernuclei and ΛΛ−ΞN\Lambda \Lambda - \Xi N coupling in ΛΛ\Lambda \Lambda--hypernuclei produce novel physics not observed in the conventional, nonstrange sector. Effects of Λ↔Σ\Lambda \leftrightarrow \Sigma conversion in Λ3^3_{\Lambda}H are reviewed. The role of ΛN−ΣN\Lambda N - \Sigma N coupling suppression in the A=4,5A=4,5 Λ\Lambda--hypernuclei due to Pauli blocking is highlighted, and the implications for the structure of    Λ10^{10}_{\;\, \Lambda}B are explored. Suppression of ΛΛ−ΞN\Lambda \Lambda - \Xi N conversion in ΛΛ     6^{\;\;\, 6}_{\Lambda \Lambda}He is hypothesized as the reason that the matrix element is small. Measurement of ΛΛ     4^{\;\;\, 4}_{\Lambda \Lambda}H is proposed to investigate the full ΛΛ−ΞN\Lambda \Lambda - \Xi N interaction. The implication for ΛΛ\Lambda \Lambda analog states is discussed.Comment: 17 pages LATEX, 1 figure uuencoded postscrip

    The Cohomology of the Sylow 2-subgroup of the Higman-Sims Group

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    In this paper we compute the mod 2 cohomology of the Sylow 2-subgroup of the Higman-Sims group HS, one of the 26 sporadic simple groups. We obtain its Poincare series as well as an explicit description of it as a ring with 17 generators and 79 relation

    Effective Widths and Effective Number of Phonons of Multiphonon Giant Resonances

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    We discuss the origin of the difference between the harmonic value of the width of the multiphonon giant resonances and the smaller observed value. Analytical expressions are derived for both the effective width and the average cross-section. The contribution of the Brink-Axel mechanism in resolving the discrepancy is pointed out.Comment: 9 pages, 4 figure
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