Theses and Dissertations

Date of Award

5-2020

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Physics

First Advisor

Dr. Soumya Mohanty

Second Advisor

Dr. Soma Mukherjee

Third Advisor

Dr. Teviet Creighton

Abstract

The Earth’s Vertical Gravity Gradient (VGG) can be used to map seafloor topography but presents a challenging inverse problem. A promising approach is forward modeling, in which one searches over a set of candidate topographies and selects the one whose predicted VGG best fits the observed one. The main bottleneck here is solving the associated high-dimensional and non-linear optimization problem. Yang et al (2018) demonstrated a method in which the topography is parametrized by heights of mass elements on a rectangular grid and the ≈ 104 dimensional optimization problem is tackled with simulated annealing (SA). We propose a computationally much cheaper method, using a stochastic optimization method known as Particle Swarm Optimization (PSO) and representing the topography as a linear combination of Radial Basis Functions (RBFs). First results, obtained without any tuning, show that the MATLAB code achieves an RMS error of 650 m with 500 RBFs (1500 parameters) and a 30 min run time. This is comparable to the error of 300 m from the much more expensive SA method that takes hours on a super-computer. Improvements to our method are likely to result in state of the art performance levels.

Comments

Copyright 2020 Yelbir Kazhykarim. All Rights Reserved.

https://go.openathens.net/redirector/utrgv.edu?url=https://www.proquest.com/dissertations-theses/topography-estimation-using-particle-swarm/docview/2459422175/se-2?accountid=7119

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