1. Department of Applied Mathematics, National Yang Ming Chiao Tung University, Hsinchu, 300093, Taiwan, Republic of China.
2. Department of Mathematics, National Taiwan Normal University, Taipei, 116325, Taiwan, Republic of China, and Chinese Air Force Academy, Kaohsiung, 820009, Taiwan, Republic of China.
3. Department of Applied Mathematics, National Pingtung University, Pingtung, 900391, Taiwan, Republic of China.
4. Department of Mathematics, National Taiwan Normal University, Taipei, 116325, Taiwan, Republic of China.