1. School of Integrated Circuits and Electronics, Beijing Institute of Technology, Beijing 100081, China
2. Hebei University of Science and Technology, 70 Yuhua Road, Shijiazhuang 050018, China
3. Department of Mechanical Engineering Science, University of Johannesburg, Kingsway Campus, Auckland Park, Johannesburg 2006, South Africa
4. Institute for Development of Energy for African Sustainability, University of South Africa, Private Bag X6, Florida 1710, South Africa