Funding for this research was provided by:
Ministry of Communications (NHHD-201503)
Chongqing University (nil)
Chongqing Science and Technology Commission (Xm2015014, cstc2017rgzn-zdyfX0025)
Shandong Science and Technology Commission (ZR2016FQ25)
Article History
Received: 20 September 2017
Revised: 17 January 2018
Accepted: 5 February 2018
First Online: 23 February 2018