A QUADRATIC ASSIGNMENT / LINEAR PROGRAMMING APPROACH TO SHIP SCHEDULING FOR THE U.S. COAST GUARD

Abstract : As part of the management planning and control function, the U.S. Coast Guard's Pacific Area Commander schedules the operational missions for all High Endurance Cutters in the Pacific Area. To provide a powerful management tool to assist this scheduling process, an analytic model for this large scale problem has been developed and implemented. It contains mission requirements, restricted sequencing of missions, ships' physical limitations and crews' morale-related considerations. The modeling approach is based on the Geoffrion-Graves model for parallel production lines with significant changeover costs. The implementation solves a large (860 row) Koopmans-Beckmann fixed charge Quadratic Assignment model using a new method with an advanced, feasible starting solution provided by an imbedded network (with 1,720 nodes and 739,600 arcs). Many linear programming problems (200 row, 450 variable) are then solved with a linear programming subroutine of advanced design. The resulting model and these implementation techniques produce excellent quality working schedules with very reasonable execution time and memory requirements. Alternative solutions are easily generated.