1. Hebei Provincial Key Laboratory of Heavy Machinery Fluid Power Transmission and Control and the Key Laboratory of Advanced Forging and Stamping Technology and Science, Yanshan University, Qinhuangdao, China
2. Xuzhou Xugong Excavation Machinery Company Ltd., Xuzhou, China
3. Qinglong County Power Supply Branch and State Grid Jibei Electric Power Company Ltd., Qinhuangdao, China