Preface

Wavelets are functions fulfilling certain mathematical requirements and used in representing data or other functions. The basic idea behind wavelets is to analyze according to scale. Wavelets received considerable attention in the last years because they are very appropriate for application in practical problems in areas of Engineering, Physics and Technology.

The book is organized in five main sections denoted as Signal Processing, Electrical Systems, Fault Diagnosis and Monitoring, Image Processing and Applications in Engineering.

The wavelet method is used in this book to extract more information than the standard techniques from a given complex signal and it has capabilities for the deconvolution framework. Applications of wavelet transform to the image processing, audio compression and communication systems are also reported.

The applications of wavelet transform in the field of power system dynamics and stability, in fault diagnosis of analogue electronic circuits as well as for practical condition monitoring issues are covered by this book. In addition the application of wavelet analysis combined with artificial neural networks as automatic rolling bearing fault detection and diagnosis is illustrated. The use of the wavelet transform to the denoising process is an important chapter of this book. The reader can see how the wavelet transform was used as a classification criterion applied to improve the compression of the hyper-spectral images.

The last chapter of the book presents some specific applications of the wavelet transform in engineering, e.g. to robust lossless data hiding by feature-based bit embedding algorithm, for the understanding of vortex-induced vibration, in rotorcraft UAV's integrated navigation system. Also, a constructive design methodology for multi-resolution- scalable mesh compression systems is presented.

The chapters of this book present the problems for which wavelet transform is best well-suited, indicates how to implement the corresponding algorithms efficiently, and finally show how to assign the appropriate wavelets for a specified application.

#### XIV Preface

Researchers, working in the field of the wavelet transform, will find several open problems being mentioned within this book. Both theoretical considerations as well as the corresponding applications are clearly presently in such a way to be understandable by a large variety of readers.
