611 research outputs found
Feasibility and cost analysis of private aircraft transportation for the University of North Dakota
Get PDFThe purpose of this study is to determine the feasibility of private aircraft transportation for the University of North Dakota and analyze the costs involved.
Safety of private aircraft transportation is discussed with emphasis on the added safety of flying in North Dakota. This additional safety factor is attributed to the low terrain, numerous airports and suitable flying weather in North Dakota.
Economic justification is determined by comparing total operating costs, which include aircraft operating costs, depreciation and value per man hour , to transportation costs incurred while traveling by commercial airlines or by University Motor Pool automobile. Value per man hour puts a quantity cost on the lost time of the University employee, faculty or administrator.
Break-even analysis of the various transportation alternatives indicate a definite justification for the proposed private aircraft transportation. Based on the expected usage of a University aircraft, ownership, instead of lease or charter, would present optimum economy.
By acquiring a private aircraft for transportation, the University should increase its management effectiveness and produce a substantial savings in transportation costs
Assessment of Models of Galactic Thermal Dust Emission Using COBE/FIRAS and COBE/DIRBE Observations
Full text linkAccurate modeling of the spectrum of thermal dust emission at millimeter
wavelengths is important for improving the accuracy of foreground subtraction
for CMB measurements, for improving the accuracy with which the contributions
of different foreground emission components can be determined, and for
improving our understanding of dust composition and dust physics. We fit four
models of dust emission to high Galactic latitude COBE/FIRAS and COBE/DIRBE
observations from 3 millimeters to 100 microns and compare the quality of the
fits. We consider the two-level systems model because it provides a physically
motivated explanation for the observed long wavelength flattening of the dust
spectrum and the anticorrelation between emissivity index and dust temperature.
We consider the model of Finkbeiner, Davis, and Schlegel because it has been
widely used for CMB studies, and the generalized version of this model recently
applied to Planck data by Meisner and Finkbeiner. For comparison we have also
fit a phenomenological model consisting of the sum of two graybody components.
We find that the two-graybody model gives the best fit and the FDS model gives
a significantly poorer fit than the other models. The Meisner and Finkbeiner
model and the two-level systems model remain viable for use in Galactic
foreground subtraction, but the FIRAS data do not have sufficient
signal-to-noise ratio to provide a strong test of the predicted spectrum at
millimeter wavelengths.Comment: 17 pages, 7 figures. Accepted for publication in Ap
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