This book is useful for researchers in application of computational techniques for machine diagnosis. It may provide a fundamental idea for accessing decision making approach for engineering applications. Author focused on Transformer diagnosis application through the support of TIFAC CORE center on "Power Transformer Diagnosis" in Electrical Engineering Department, National Institute of Technology Hamirpur under the guidance of Dr.Raj Kumar Jarial. TIFAC CORE is a consultancy and research center supported by Department of science and Technology, Govt. of India. TIFAC CORE offers admissions of for M.Tech and Ph.D in the nodal areas of the center. Further details can be found at: http://tifac.nith.ac.in/