Copyright 1997 by Loyola College in Maryland. This work relates to NSF Cooperative Agreement ENG-9416970. The U.S. government retains a nonexclusive and nontransferable license to exercise all exclusive rights provided by copyright. The ISBN number for this report is 1-883712-46-7. This report is distributed by the National Technical Information Service (NTIS) of the U.S. Department of Commerce as NTIS report # PB98-103161. A list of available JTEC/WTEC reports and information on ordering them from NTIS is available.