1. Oak Ridge National Laboratory, Fuels, Engines, and Emissions Research Center, National Transportation Research Center, 2360 Cherahala Boulevard, Knoxville, TN 37932 e-mail:
2. Oak Ridge National Laboratory, Fuels, Engines, and Emissions Research Center, National Transportation Research Center, 2360 Cherahala Boulevard, Knoxville, TN 37932
3. Chevron Energy Technology Company, 6001 Bollinger Canyon Road, San Ramon, CA 94583