
Acknowledgment
First and foremost, I would like to thank my academic advisor, Associate
Professor Phan Thanh An, for his guidance and constant encouragement.
The wonderful research environment of the Institute of Mathematics, Viet-
nam Academy of Science and Technology, and the excellence of its staff have
helped me to complete this work within the schedule. I would like to express
my special appreciation to Professor Hoang Xuan Phu, Professor Nguyen
Dong Yen, Associate Professor Ta Duy Phuong, and other members of the
weekly seminar at Department of Numerical Analysis and Scientific Com-
puting, Institute of Mathematics, as well as all the members of Associate
Professor Phan Thanh An’s research group for their valuable comments and
suggestions on my research results. In particular, I would like to express
my sincere thanks to Associate Professor Nguyen Ngoc Hai and PhD student
Nguyen Thi Le for their significant comments and suggestions concerning the
research related to Chapters 1, 2 and Chapter 3 of this dissertation.
I would like to thank the members of the Thesis Evaluation Committee at
the Department-Level and the Thesis Evaluation Committee at the Institute-
Level (Professor Nguyen Dong Yen, Professor Le Dung Muu, Associate Pro-
fessor Truong Xuan Duc Ha, Associate Professor Nguyen Nang Tam, Asso-
ciate Professor Nguyen Trung Thanh, Associate Professor Nguyen Thi Thu
Thuy, Doctor Hoang Nam Dung, Doctor Nguyen Duc Manh, Doctor Le Xuan
Thanh and Doctor Le Hai Yen), and the two anonymous referees, for their
careful readings of this dissertation and valuable comments.
Finally, I would like to thank my family for their endless love and uncon-
ditional support.
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