1. State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou 730050, China
2. School of Science, Lanzhou University of Technology, Lanzhou 730050, China
3. School of Electronic and Information Engineering, Chongqing Three Gorges University, Chongqing, Wanzhou, 404000, China
4. Science and Technology on Vacuum Technology and Physics Laboratory, Lanzhou Institute of Physics, Gansu, Lanzhou, 730000, China