This thesis is the account of three years of devoted work in the field of applied electrostatics at the University Institute of Technology in Angouleme, at the Technical University of Cluj-Napoca, and at Hamos GmbH Penzberg which would not have been possible without the help of many.

A few lines are too short to make a complete account of my deep appreciation for my advisors Lucian DASCALESCU and Alexandru IUGA. It all started four years ago, when they were both my graduate advisors. As most of the present PhD thesis was completed while with the Electronics and Electrostatics Research Unit at IUT d’Angouleme, under the supervision of prof. Lucian DASCALESCU, I wish to thank him for his unflattering trust and constant encouragements which have been essential to our success through the last three years. I wish to thank him for who he is as a professor: an enthusiastic, sagacious, honest minded individual with broad interests who provides steady support in the most difficult times. His trust and honesty, his efforts in understanding a student’s personality and tailoring his approach accordingly translated for me into, although away from home, a very pleasurable 20-month stay at Angouleme. My apprentice pursuit into the world of science would not have been the same without prof. Alexandru IUGA’s approach to research and science, which made me take the decision, after long internal struggles, to embrace the amazing field of applied electrostatics. I want to extend my appreciation for his patience, for his full devotion to others, for his great understanding, and for the lessons he gave me on the importance of details for the success of an engineering or scientific project. It has been a distinct privilege for me to work with both Professor Alexandru IUGA and Professor Lucian DASCALESCU.

I am deeply honoured by the fact that the jury in front of which I shall defend my PhD thesis will be chaired by Prof. Radu MUNTEANU, member of the Romanian Academy of Technical Sciences, Rector of the Technical University of Cluj-Napoca, who has always been for me the incarnation of the utmost intellectual and academic distinction. I am also deeply indebted to him for the opportunity to prepare this co-supervised thesis, as he was the one who recommended me for an ERASMUS scholarship at the University of Poitiers, in the final year of my engineering studies.

Prof. Hubert ROMAT is a distinguished specialist in Electrostatic Processes, whom I first met during one of his visits at the Technical University of Cluj-Napoca, and with whom I also had the opportunity to discuss at the 2004 IEEE-IAS Annual Meeting, in Seattle. I wish to thank him for honouring me by accepting to Co-chair the jury that will examine my PhD thesis.

Although our meeting, 3 years ago, was rather brief, I owe Professor Olivier LESAINT, Director of LEMD-CNRS, Grenoble, France, a fruitful analysis of various measurement techniques that I was planning to approach in my thesis. His good advice helped me focus on the right issues. I am grateful for that, as well as for his acceptance to report on my work, in spite of his very busy schedule.

The other external report on my PhD thesis will be prepared by Professor Petru NOTINGER, Director of Electrotechnical Materials laboratory at the Politehnica University, Bucharest. I thank him very much for the time he will spend on this task, as well as for having recommended me, two years for the Scholarship of French Government that financed the last 12 months of my stay at Angoulême.

I would like to thank here Professor Claude TEMPLIER, Director of the Doctoral School of the University of Poitiers, and Prof. Gerard CHAMPENOIS, director of LAII for accepting me as a co-supervised PhD student at the University Institute of Technology, Angoulême.

During my stay with the Electronics and Electrostatics Research Unit in Angoulême, I have benefited of Professor Adrian SAMUILA’s rigorous and critic attitude, as well as of his accurate understanding of electrostatic phenomena. I am grateful to him for sharing with me his deep knowledge on particle charging and discharging processes, which motivated me into developing part of the measurement methods presented in the thesis.

Smail BACHIR, Associate Professor at the University Institute of Technology, Angoulême, introduced me to signal identification techniques, currently used in Automatics. I gladly acknowledge his helping me in identifying non integer function models for the charge decay of granular layers of insulating materials in contact with grounded electrodes.

I would like to extend my thanks to Dr. Rainer KÖHNLECHNER for accepting me for 6 months as a member of his research team at Hamos on the Mineral Separator project, helping me in so many occasions to keep in mind the practical engineering importance of subjects we studied and for contributing to my understanding of how those engineering constructs relate to one another and to the practical world of electrostatic separation.

My experience at Hamos would not have been such a pleasurable one without the presence of all the people working there. I wish to thank Dr. Florian AMAN for sharing with me his unstoppable taste for turning ideas into practical innovations. My thanks will go also to eng. Ufer REINHARD and eng. Petra KOBER who supported me all along my project at Hamos.

To Professor Roman MORAR I owe a welcomed acceptance into de High-Intensity Electric Fields Laboratory (HIEFL) at Technical University of Cluj-Napoca. His constant encouragements and trust hearten me.

It was a particular pleasure to work with associate professor Vasile NEAMTU whose previous work on industrial electrostatic separators was the ground of some my work and also with eng. Ilie SUARASAN, during the time I spend in Cluj. I thank them for associating me to some of their work.

I wish to extend my thanks to the whole staff either be it at University Institute of Technology in Angouleme or at Technical University Cluj-Napoca. Particularly I thank Marie-Dominique VILLARDS, Manola DUQUERROY, Valerie DOURSOUT, Chantal TASCHER and Rodica BRAD for theirs kindness and dedication to students, Marc GAUTHIER and Costel PETRU for their essential support on technical issues and prototyping.

I had the chance to participate at two “Annual Meetings” of IEEE’s, Industry Application Society under the Myron Zucker Student Travel Program. I thank Joseph SOTTILE, head of the IAS’s Educational Department, for the opportunity of meeting so many great people there, twice.

There are two of my school teachers that I would like to acknowledge here as their trust and unfaltering encouragements set me on the right track: Eugenia POP and Doina LUPU.

Without friends, life as a graduate student would not be the same.

As I got to know them during my last year in France, Subhankar DAS and Karim MEDLES become special friends of mine. The many discussions we had, be they research-related or not, were often the occasion for new discoveries and always truly agreeable moments.

I’ve known Laur CALIN and Marius BLAJAN, since preparing my graduation project. Although we have not always agreed, their friendship is valuable to me and I want to thank them for their pragmatic approach to problem solving and their honesty.

I would like to thank now Dr. Ahmed EL OUALKADI, and Dr. Faeza AMROUCH, both belonging to Electronics and Electrostatics Research Unit in Angoulême, for their help on approaching filters and signal conditioning issues. Their company was always a pleasure for me.

I can’t skip mentioning my friends from Valachia University: Oana MARIN, Iuliana ZAFIU, Mircea STANCULESCU, and Ciprian OPRESCU. We have known each other during the training period they spent in Angouleme. They contributed to various experimental parts of this research. Oana is a truly devoted person and I thank her for the time and passion she put into our work. Iuliana and Mircea proved to be as efficient in their work as they were at being the good spirit of the group. We have work together in developing some remarkable virtual instruments. I hope we will all meet again sometimes.

Gabriel SUDRET was a special person through my life as a graduate student in France. I owe him a taste of “bon et bien vivre”, and many wonderful voyages.

All my friends, I thank them for bearing my little availability, recurrent bad temper and irascibility trough those last years.

I wish to thank my family: my sister Anca and my grand parents, Paulina, Maria and Gheorghe for their prayers and their encouragements throughout my graduate work in France.

Obviously, I would not be sitting in front of my monitor typing these acknowledgement lines without my Mom and Dad. I owe my parents, Florian and Rodica MIHALCIOIU much of what I have become. I thank them for their love, their support, and their confidence throughout the past twenty-six years. My parents have always put education as a first priority in my life, and raised me to set high goals for myself. They taught me to value honesty, courage, and humility above all other virtues. I have always needed to work hard to achieve my goals in life and they have always been there for me as an unwavering support. I dedicate this work to them, to honour their love, patience, and support during these years.