First and foremost.1 will convey my heartfelt gratitude to mysupervisor,distinguished Professor Dai Wei dong.It is a great honor and my best luck to have him as my supervisor.I am grateful to him for hisgracious guidance,invaluable suggestions and constant encouragement,without which this book would never have been possible.Further,special gratitude goes to Professor Dai for his care about my life here.Professor Dai is not only a great scholar but also a gentleman of greatcharacter.His kindness impresses all his students deeply.