1. Ph.D. Student, Dept. of Aerospace Engineering, Iowa State Univ., Ames, IA 50011.
2. Dept. of Aerospace Engineering, Iowa State Univ., Ames, IA 50011.
3. Ph.D. Student, Dept. of Energy Technology, Aalborg Univ., Pontoppidanstraede 111, 9220 Aalborg East, Denmark (corresponding author).