1. Nanyang Technological Univ.,Energy Research Inst.,Singapore,639798
2. Chinese Univ. of Hong Kong,School Electric. Electron. Eng.,Hong Kong,China,999077
3. Southwest Jiaotong Univ.,School Electric. Electron. Eng.,Chengdu,China,610032
4. Nanyang Technological Univ.,School Electric. Electron. Eng.,Singapore,639798