This first volume of a set dedicated to the reliability of high-power mechatronic systems focuses specifically on simulation, modeling and optimization in automotive and aerospace applications. In the search to improve industrial competitiveness, the development of methods and tools for the design of products is especially pertinent in the context of cost reduction. This book seeks to propose new methods that simultaneously allow for a quicker design of future mechatronic devices in the automotive and aerospace industries while guaranteeing their increased reliability. The reliability of these critical elements is further validated digitally through new multi-physical and probabilistic models that could ultimately lead to new design standards and reliable forecasting.