1. Assoc. Prof. of Mechanics and Hydraulics, Univ. of Iowa, and Research Engr., Inst. of Hydr. Research, Iowa City, Iowa
2. Research Assoc., Inst. of Hydr. Research, Iowa City, Iowa
3. Research Asst., Inst. of Hydr. Research, Iowa City, Iowa, on leave from Andhra Univ., Waltair, India