The objective of my previous book,Vibration Control of Active Struc-tures, was to cross the bridge between Structural Dynamics and Auto-matic Control. To insist on important control-structure interaction issues, the book often relied on “ad-hoc” models and intuition (e.g. a thermal analogy for piezoelectric loads), and was seriously lacking in accuracy and depth on transduction and energy conversion mechanisms which are essential in active structures. The present book project was initiated in preparation for a new edition, with the intention of redressing the imbal-ance, by including a more serious treatment of the subject. As the work developed, it appeared that this topic was broad enough to justify a book on its own.