1. Assistant Professor, Univ. of Nebraska–Lincoln, 241 L. W. Chase Hall, East Campus, Biological Systems Engineering, Lincoln, NE 68583 (corresponding author).
2. Professor and Orville L. and Helen L. Buchanan Chair, Oklahoma State Univ., Dept. of Biosystems and Agricultural Engineering, Stillwater, OK 74078.
3. Professor, Oklahoma State Univ., Dept. of Biosystems and Agricultural Engineering, Stillwater, OK 74078.