Acknowledgements

I would like to acknowledge Prof. Dr. Robert Mattheij, head of the Scientific Computing group, for offering me the possibility to work on this subject. I would also like to thank Dr. Ir. Arris Tijsseling for supervising this thesis. His advices, comments and support throughout this period were fundamental. Special thanks to Dr. Ir. Bas van der Linden, whose technical and scientific support has been extremely helpful. I would like to express my esteem for Prof. Dr. Axel Klar from Technische Universität Kaiserslautern, who kindly agreed to give his valuable comments on my thesis and whose lectures were a delight to visit in my first year in Kaiserslautern. I wish to express my gratitude to my friends and colleagues, Alexandru Mereacre