This book deals with ultrasonic nondestructive evaluation (NDE) inspections where high frequency waves are used to locate and characterize dangerous flaws (such as cracks) in materials. Ultrasonic NDE flaw inspections involve a very complex combination of electrical, electromechanical, and acoustic/elastic components so that it is important to understand the behavior of those components and their interactions in order to make quantitative flaw measurements. It will be shown that through the use of models and measurements it is now possible to characterize all the elements of an ultrasonic NDE...