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Doctoral Thesis
DOI
https://doi.org/10.11606/T.18.2003.tde-19122003-185113
Document
Author
Full name
Túle Cesar Barcelos Maia
E-mail
Institute/School/College
Knowledge Area
Date of Defense
Published
São Carlos, 2003
Supervisor
Committee
Segantine, Paulo Cesar Lima (President)
Fonseca Junior, Edvaldo Simões da
Monico, Joao Francisco Galera
Romero, Roseli Aparecida Francelin
Sa, Nelsi Cogo de
Title in Portuguese
Utilização de redes neurais na determinação de modelos geoidais
Keywords in Portuguese
FFT
geóide
gravimetria
modelo geopotencial
ondulaçõa geoidal
PCA
redes GPS
redes neurais
Abstract in Portuguese
A partir de dados obtidos do modelo do geopotencial EGM96, da gravimetria, do GPS e do nivelamento geométrico, e aplicando harmônicos esféricos e FFT como técnicas de determinação geoidal, foram utilizadas neste trabalho redes neurais artificiais como ferramenta alternativa na determinação de um modelo geoidal. Procurou-se uma determinação geoidal de forma mais rápida, com precisão adequada e com menor esforço na determinação de parâmetros importantes na obtenção da referida superfície. Foram utilizados modelos de redes neurais do tipo MLP, algoritmo de treinamento backpropagation, variando o número de camadas, o número de neurônios, a função de ativação, a taxa de aprendizado e o termo momento. Os dados dos modelos mencionados foram tratados de forma a serem utilizados pelos modelos de redes neurais. Foram executadas a normalização, a análise de componentes principais e a definição dos atributos de entrada e saída para treinamento do modelo de rede neural. Foram Realizadas comparações entre os modelos geoidais existentes, os quais foram utilizados nesta pesquisa, com os resultados obtidos pelo modelo de rede neural. Tais comparações resultaram na obtenção dos erros entre as superfícies, justificando dessa forma a possibilidade de uso do referido método, com a conseqüente demonstração de suas vantagens e desvantagens.
Title in English
Using artificial neural network to obtain geoid models.
Keywords in English
FFT
geoid
geoidal ondulation
geopotencial model
GPS network
gravimetry neural networks
PCA
Abstract in English
Applying data from EGM96 geopotential model, gravimetric, GPS and geometric leveling data and using spherical harmonics and FFT as techniques of geoidal determination, this thesis has the goal to find a fast alternative tool to define a geoidal undulation model considering precision and a small effort to estimate important parameters to obtain the mentioned model. MLP neural networks, backpropagation algorithm changing the numbers of layers, neurons numbers, activation function, learning rate and momentum term have been applied. The data of the mentioned models were handling aiming to be used by the neural networks models. Normalization, analysis of the main components, definition of the input and output attributes to training the neural network model, have been also used. Comparison among existing models and the models used in this research with results obtained by the neural network have been done, showing the errors between the created surfaces. At the end, it is presented a positive argument to use the MLP neural network to generate a geoidal model with advantages and disadvantages.
 
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Tule_Tese.pdf (78.36 Mbytes)
Publishing Date
2005-04-07
 
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