“…picking sequence, picking distance, picking time, storage policy and order frequency (Bukchin, Khmelnitsky, & Yakuel, 2012;Gademann & Van de Velde, 2005;Grosse, Glock, & Jaber, 2013;Wutthisirisart, Noble, & Chang, 2015). Typically, items with high order frequencies are stored close to the P/D point to reduce the S/R activity duration (Chuang, Lee, & Laih, 2012;Goetschalckx & Ratliff, 1990;Kutzelnigg, 2011;Le-Duc & De Koster, 2005;Manzini, Gamberi, & Regattieri, 2005;Petersen, Aase, & Heiser, 2004). Assignment strategies for UL warehouses face the ULAP seeking the minimum average travelled time and distance for the S/R activities.…”