This book is a sequel to two previous publications on signal analysis applications. It applies the standard tools of signal analysis, such as differential calculus, probability theory, mechanism processes, partial differential equations, group theory, and linear algebra, to a variety of problems in physics and engineering. The book is a blend of theory and practice. In some problems, a new theoretical method is developed and in others a well-known theoretical method is applied to a new practical problem. The book will be of interest to theoretical and experimental physicists, engineers and applied mathematicians. Research students of applied mathematics and engineering will find the book useful for providing new suggestions to existing problems and also for suggesting new research problems in their fields.