zur Erlangung des akademischen Grades eines DOKTOR-INGENIEURS

his support, his encouragement, and guidance during my research. I am also very grateful to Dr. Eric Walter for being supervisor of my doctoral thesis and for his careful reading of the manuscript and for his valuable advices. Furthermore I would like to thank my former colleague Dr.-Ing. Andreas Rauh for the many precious discussions and suggestions and for the great collaboration during my time at the Institute. I would also like to thank Prof.-Dr.-Ing. Harald Aschemann for his support. Special thanks to my friend Dr.-Ing. Felix Antritter for a very fruitful cooperation and making it possible to extend my field of research. Also thanks to all of my students for their excellent work. My deepest gratitude belongs to my beloved wife Jane. Her constant support helped me also through difficult times. And I also thank my three little children for being patient with their Dad, when he was too busy to play with them. For my beloved wife Jane ”Many women have done excellently