The principles and applications of ultrasound waves are described in this up-to-date book. Ultrasonic waves have applications in a variety of fields such as medicine, engineering, biology, physics, etc. This book includes contributions from prominent researchers around the globe and introduces various applications of ultrasonic waves. It discusses topics such as phased array modelling, ultrasonic thrusters, positioning systems, tomography, projection, gas hydrate bearing sediments and Doppler Velocimetry which, combined with substances characterization, mining, corrosion and gas removal by ultrasonic technology, form an interesting set of updated information. Theoretical advances on ultrasonic wave investigation are also showcased in this book, especially about topics like modelling the generation and distribution of waves, and the influence of Goldberg's number on estimation for finite amplitude acoustic waves. Readers will find this book a valuable source of knowledge where authors have explained their research works in a clear way, basing them on relevant bibliographic references and real challenges of their area of study.