\chapter*{Acknowledgments}
\addcontentsline{toc}{chapter}{Acknowledgments}

First of all, I would like to deeply thank my director of studies Prof.\ Steven
Wilcox for his scientific advice and orientation, exhaustive corrections, and endless
patience. I also would like to express my gratitude to my supervisor Prof.\ Robert
Reuben for helping setting up initial goals and his technical guidance. I am also
very grateful to Clive Monks for his aid with the experimental work on the CNC centre
and the manufacturing of some mechanical parts, and to Gareth Betteney for his help
on the electronic circuitry.

Secondly, I would like to thank the innumerable friends that I have socialized with
during the last interminable years that I have lived in Wales, London, and Portugal.


Finally, the most special thanks to my closest family: my aunts Maria Jos\'e,
Felisbina, and Maria, my two sisters (Zefa and Quela), and my mother (Madalena).
