1. Department of Mathematics Taiyuan Normal University Jinzhong China
2. Institute of Advanced Forming and Intelligent Equipment Taiyuan University of Technology Taiyuan China
3. Key Laboratory for Engineering & Computational Science Taiyuan Normal University Jinzhong China
4. Hefei Innovation Research Institute of Beihang University Hefei China
5. Engineering Research Center of Ministry of education of heavy machinery Taiyuan University of Science and Technology Taiyuan China