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Numerical Modeling of Propagation of Sound Waves in an Inhomogeneous and Moving Medium of the Atmospheric Troposphere Layer
, M.Sc. Thesis Sharif University of Technology ; Taeibi Rahni, Mohammad (Supervisor) ; Massah, Hamid Reza (Co-Advisor)
Abstract
Troposphere layer includes complex flows which their effects in acoustic sensors are indicated as acoustic wave noise.It is essential to analyze these complex flows to recognize how to reduce the noise. In this thesis we have perused and modeled the sound wave propagation in troposphere layer.Given data are some thermal and velocity profiles of atmospheric flowsthe assumptions are: 1- gravity waves are negligible, 2- air density depends only on altitude, 3- sound waves parabolic equation assumptions are applied. Our goal Is to find the sound pressure level originated from a sound source in troposphere layer.This thesis emphasizes on analysis, recognition and modeling of the problem. Main...
Measuring Limb Darkening of Distant Stars Using Microlensing Events by Finite Element Method
, Ph.D. Dissertation Sharif University of Technology ; Rahvar, Sohrab (Supervisor)
Abstract
The finite-size effect in gravitational microlensing provides a possibility to measure the variation of surface brightness of stars from centre to limb which is called limb darkening profile. Measuring limb darkening profile provides information about star atmosphere. It is also useful in other fields of astrophysics. In this thesis we develop a numerical method to recover limb darkening of source stars from single lens microlensing light curves with finite source effect in which the lens transits the source disk. We use the Finite Element Method (FEM) as an inversion tool for discretization and inversion of the finite source effect integral equation. This method makes no explicit assumption...