Robust Simulation-optimization Methods Using Kriging Metamodels

Acknowledgements Now that I become closer and closer to the end of this adventure, I would like to deeply thank some people who helped me — in different ways and at different stages of my PhD — to achieve this goal. First of all, I want to thank my advisors: Carlo Meloni, for having introduced me to the fascinating world of research, for his being always so supportive to me, and for his willingness to discuss some research issues, going on until a suitable solution was found. Tiziano Politi, for having provided me the important background I needed to tackle the topic that, afterwards, evolved into the present dissertation. Jack Kleij-nen, for having given me the opportunity to visit Tilburg University and personally collaborate with him; thanks to our intensive and productive meetings, I learned so much during the year I spent working there. I would also like to thank my former roommate , Wim Van Beers, with whom I shared the office during my stay in Tilburg: he was always available to help me, no matter whether he was busy or not; I will never forget what he told me one day I felt a bit frustrated for my research having temporarily come to a stop: " Keep smiling! ". I will... Many thanks also to Dick den Hertog and Inneke Van Nieuwenhuyse for the stimulating and thorough discussions which definitely improved the outcome of my work. Besides the results discussed in this thesis, I cooperated in some research projects at the Politecnico di Bari: therefore, I wish to thank Alessandro Rizzo e Paolo Lino, who — together with Carlo Meloni — have been my first research group and initiated me into my PhD, always making me feel at ease. I am grateful to the referees of my dissertation, Alessandro Agnetis, Bill Biles and Renato De Leone, who gave me valuable remarks to improve the quality of my PhD thesis; their comments really encouraged me to keep on working on this topic. Finally, I want to thank my parents, for their discreet support and for giving me all I needed to concentrate on work whenever I had to. Thanks to my friends for their perseverance in inviting me to have fun together, despite all the times I answered 'no'. In the end, I heartily thank my fiancé, Giulio, for his infinite love, his support and encouragement and for always …