Scheduling Reclaimer Operations in the Stockyard to Minimize Makespan

This paper considers a reclaimer scheduling problem in which one has to collect bulk material from stockpiles in the quay in such a way that the time used is minimized. When reclaimers are allowed to work on the same stockpile simultaneously, a fully polynomial time approximation scheme（FPTAS） is designed. Further,we present a 2-approximation algorithm in the case that any stockpile can be handled by only one reclaimer at a time. When the number of reclaimers is two, we give a 3/2-approximation algorithm. Numerical experiments show that the algorithms perform much better than our worst case analysis guarantees.