I would like to express my sincere thanks to my supervisor Prof. J. Fidler for his encouragement, guidance, support and fruitful discussions throughout this work.
I am very grateful to Univ. Doz. Dr. Thomas Schrefl for many stimulating discussions, his advice related to all aspects of this work, and his patience in answering all my questions and concerns. He supported me with many references to important literature, tips for implementing the finite difference model, and his implementation of the finite element model, which I adapted for my needs.
Prof. Fidler initiated this work and gave me the opportunity for a short term visit to the ``Computational Magnetism'' group of Prof. Roy W. Chantrell at the University of Wales, Bangor. Thus, I wish to express my sincere thanks to Prof. Chantrell for his invitation to Bangor, where I learned a lot from his knowledge on thermal activation in micromagnetics and started the finite difference model.
Special thanks to Dieter Süss for many helpful discussions and support.
Finally I would like to express my sincere thanks to my parents, who made my studies possible, for their continuous support and encouragement.