1. AML, Department of Engineering Mechanics, Tsinghua University, Beijing 100084,China
2. Institute of High Performance Computing, A*STAR, Singapore 138632, Singapore e-mail:
3. Department of Engineering Mechanics, School of Science, Wuhan University of Science and Technology, Wuhan 430065, China
4. Institute of High Performance Computing, A*STAR, Singapore 138632,Singapore
5. School of Engineering, Brown University, Providence, RI 02912