J.J. Dai, PhD, is a retired physical scientist and electrical engineer. He has authored and co-authored more than 30 technical papers in the field of power system modeling and analysis. He is a registered Professional Engineer in the state of California, USA, a Member of IEEE, and a past Chairman of the Power System Analysis Subcommittee of the IEEE Industrial Applications Society (IAS). He has been actively involved in the development of IEEE standards on industrial and commercial power system analysis.