1. School of Science, Xi'an Polytechnic University,Xi'an,China,710048
2. Engineering Research Center of Flexible Radiation Protection Technology of universities of Shaanxi Province, Xi'an Polytechnic University,Xi'an,Shaanxi,P.R. China,710048
3. Dalian Boiler and Pressure Vessel Inspection & Testing Institute Co, Ltd.,Dalian,China,116016