This book is a sequel to the two previous books on signal analysis applications. The book applies the standard tools of signal analysis like differential calculus, probability theory, mechanism processes, partial differential equations, group theory and linear algebra to a variety of problems in physics and engineering that arise in practical applications. The book is a blend of theory and practices. In some problems, a new theoretical method is developed and in some 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 extremely useful for providing new suggestions for existing problems and also for suggesting new research problems in their fields.