A reclaimer scheduling problem arising in coal stockyard management
  We study a number of variants of an abstract scheduling problem inspired by the scheduling of reclaimers in the stockyard of a coal export terminal. We analyze the complexity of each of the variants, providing complexity proofs for some and polynomial algorithms for others. For one, especially interesting variant, we also develop a constant factor approximation algorithm. 
Enrico Angelelli, Thomas Kalinowski, Reena Kapoor, Martin W.P.   Savelsbergh
cs.DS