20,992 research outputs found

    The roles of kinetic theory and gas-surface interactions in measurements of upper-atmospheric density

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    Kinetic theory and gas-surface interactions in measurements of upper atmospheric densit

    Rational cuspidal curves with four cusps on Hirzebruch surfaces

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    The purpose of this article is to shed light on the question of how many and what kind of cusps a rational cuspidal curve on a Hirzebruch surface can have. We use birational transformations to construct rational cuspidal curves with four cusps on the Hirzebruch surfaces and find associated results for these curves.Comment: 26 pages, 1 figur

    A new method of determining the mean molecular mass

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    Method for determining mean molecular mass in upper atmospher

    Six reasons why thermospheric measurements and models disagree

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    The differences between thermospheric measurements and models are discussed. Sometimes the model is in error and at other times the measurements are, but it also is possible for both to be correct, yet have the comparison result in an apparent disagreement. These reasons are collected for disagreement, and, whenever possible, methods of reducing or eliminating them are suggested. The six causes of disagreement discussed are: actual errors caused by the limited knowledge of gas-surface interactions and by in-track winds; limitations of the thermospheric general circulation models due to incomplete knowledge of the energy sources and sinks as well as incompleteness of the parameterization which must be employed; and limitations imposed on the empirical models by the conceptual framework and the transient waves
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