1. Department of MathematicsNanjing University of Aeronautics and AstronauticsNanjingPeople's Republic of China
2. Business School, University of Shanghai for Science and TechnologyShanghaiPeople's Republic of China
3. School of Science, Dalian Jiaotong UniversityDalianPeople's Republic of China
4. Academy of Mathematics and Systems ScienceChinese Academy of SciencesBeijingPeople's Republic of China