Affiliation: | School of Mechanical and Electronic Engineering, Northwest Polytechnic University, Xi'an 710072, China Department of Mathematics and Physics, Henan University of Science and Technology, Luoyang 471039, China;Department of Mathematics, Lanzhou University, Lanzhou 730000, China Department of Mathematics and Physics, Henan University of Science and Technology, Luoyang 471039, China School of Mechanical and Electronic Engineering, Northwest Polytechnic University, Xi'an 710072, China |