1. Faculty of Mechanical and Precision Instrument Engineering; Faculty of Printing, Packing and Digital Media Engineering, Xi'an University of Technology, Xi'an 710048, China e-mail:
2. Faculty of Mechanical and Precision Instrument Engineering, Xi'an University of Technology, Xi'an 710048, China e-mail:
3. School of Civil Engineering and Architecture, Xi'an University of Technology, Xi'an 710048, China e-mail:
4. Faculty of Printing, Packing and Digital Media Engineering, Xi'an University of Technology, Xi'an 710048, China e-mail: