1. School of Mechanical Engineering North China University of Water Resources and Electric Power Zhengzhou China
2. Sichuan Rural Energy Office Chengdu China
3. College of Architecture and Environment Sichuan University Chengdu China
4. Biogas Institute of Ministry of Agriculture, Risk Assessment Lab of the Quality Safety of Biomass Fermentation Products (Chengdu) Ministry of Agriculture and Rurals Affairs Chengdu China
5. Department of Population Health and Reproduction, School of Veterinary Medicine University of California Davis Davis California USA