1. School of Civil Engineering and Mechanics, Lanzhou University, Lanzhou, People’s Republic of China
2. National Research Center for Conservation of Ancient Wall Paintings and Earthen Sites, Dunhuang, People’s Republic of China
3. Key Laboratory of Conservation of Ancient Wall Paintings and Earthen Sites in Gansu, Dunhuang, People’s Republic of China
4. College of Cultural Heritage, Northwest University, Xi’an, People’s Republic of China