1. Agricultural Engineer, Av. Santa Fe 2271, 8th Floor B, 1123 Buenos Aires, Argentina. E-mail: gabrielvazquez@alumni.purdue.edu
2. Professor, Agricultural and Biological Engineering Dept., Purdue Univ., ABE Bldg., 225 University St., West Lafayette, IN 47907-2093. E-mail: engelb@purdue.edu