“…Recently, the existing work on supply uncertainty can be divided into three categories: (i) the random-yield model, which models the uncertainty by assuming that the supply level is a random function of the input level (e.g. Babich, Ritchken, Burnetas [4]; Deo, Corbett [5]; Federgruen, Yang [6]; Gao, Li, Shou [7]; Kazaz [8]; Parlar, Wang [9]; Swaminathan, Shan-thikumar [10]; Wang, Gilland, Tomlin [11]; Fang & Shou [12]); (ii) the stochastic lead-time model, which models the lead-time as a random variable(e.g. Zipkin [13]), and (iii) the supply disruption model, which typically models the uncertainty of a supplier as one of two states: "up" or "down" (see Arreola-Risa, DeCroix [14]; Meyer, Rothkopf, Smith [15]; Parlar, Berkin [16]; Song, Zipkin [17]; Tomlin [18]).…”