同时我也想感谢我的爸爸妈妈，焉得谖草，言树之背，养育之恩，无以回报，你

At the same time, I would also like to thank my parents and mothers. They have won the grass, the back of the tree, the grace of nurturing, and there is no return. You are always healthy and happy is my biggest wish. Although the thesis has been written this time, but my mood has calmed down. From the beginning of the selection of the topic to the successful completion of the graduation thesis, how many respectable teachers, classmates and friends have given me speechless help. Sincere thanks! At the same time, I would also like to thank the college for the platform provided to us. Finally, once again thank the mentor and friend who helped me in the graduation project and the classmates who studied in the same class, as well as the author of the work that I quoted or referred to in the paper. Without everyone's help, my thesis cannot go so smoothly, thank you all for your help!

At the same time, I also want to thank my parents, the grass, the back of the tree, the grace of parenting, no return, you always healthy and happy is my greatest wish. Although the thesis has been written, but my mood is quiet, from the beginning of the selection of topics to the successful completion of the graduation thesis, how many respectable teachers, classmates, friends gave me silent help, here please accept my sincere thanks! At the same time also thank the Academy for providing us with the platform, and finally, once again, thanks in the graduation design has helped my mentors and friends and classmates reading in the same window, as well as in the paper I quote or refer to the author of the thesis. Thanks to everyone for helping my papers go so smoothly!

At the same time, I also want to thank my parents. How can I have the grass, the back of the tree, the grace of nurturing, no return? Your eternal health and happiness are my greatest wish. Although this thesis has been finished, my mood is still. From the beginning of choosing a project to the successful completion of my graduation thesis, how many respectable teachers, classmates and friends have given me speechless help. Please accept my sincere thanks here! At the same time, I also thank the college for providing us with a platform. Finally, I would like to thank once again my mentor and classmates who have helped me in my graduation project, as well as the authors of the works that I quoted or referred to in my thesis. Without your help, my thesis can not go so smoothly. Thank you for your help!