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Full-Text Articles in Physical Sciences and Mathematics
A Study Of A Reimaging System For Correcting Large-Scale Phase Errors In Reflector Antennas, Eugene F. Lauria
A Study Of A Reimaging System For Correcting Large-Scale Phase Errors In Reflector Antennas, Eugene F. Lauria
Masters Theses 1911 - February 2014
This thesis investigates a new approach for dealing with the adverse effects of large-scale deformations in the main reflector of large Cassegrain antennas. In this method, the incident aperture distribution is imaged onto a tertiary focal plane. This is accomplished by using an optical imaging system consisting of a lens mounted behind the Cassegrain focus of the antenna. The lens forms a real image of the product of the incident aperture distribution and the pupil function of the antenna. The pupil function describes the profile of the main reflector of the antenna. If the incident aperture distribution is a plane …
Bar-Spheroid Interaction In Galaxies, Lars Hernquist, Martin D. Weinberg
Bar-Spheroid Interaction In Galaxies, Lars Hernquist, Martin D. Weinberg
Astronomy Department Faculty Publication Series
The secular evolution of barred galaxies is explored using N-body simulation and linear analysis. In particular, we examine the interaction between bars and spheroidal components of galaxies. According to our calculations, this interaction drives secular transfer of angular momentum from bars to spheroids, primarily through resonant coupling. A moderately strong bar, having mass within corotation ~0.3 times the enclosed spheroid mass, is predicted to shed all its angular momentum typically in less than ~10^9^ yr, which is quite short compared to the ages of galactic disks. Even shorter depletion time scales are found for relatively more massive bars. Given that …