1. School of Electrical and Computer Engineering, Oklahoma State University, Stillwater, OK 74078 USA.
2. Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 USA. He is now with the Electric Power Research Institute, Palo Alto, CA 94304 USA.
3. Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180 USA.
4. Department of Electrical Engineering and Computer Science, The University of Tennessee, Knoxville, TN 37996 USA.