1. School of Civil EngineeringChongqing University Chongqing 400045 China
2. College of Defense EngineeringPLA University of Science and Technology Nanjing 210007 China
3. Department of Mechanical EngineeringNorwegian University of Science and Technology Trondheim 7491 Norway
4. College of Letters and ScienceUniversity of California Los Angeles CA 90095 United States