1. Xi’an Thermal Power Research Institute 1 , Xi’an 710032, People’s Republic of China
2. Dongfang Power Plant of Huaneng Hainan Power Generation Co., Ltd. 2 , Dongfang 562700, People’s Republic of China
3. Key Laboratory of Nondestructive Testing (Ministry of Education), Nanchang Hangkong University 3 , Nanchang 330063, People’s Republic of China