810635.fig.001a
(a) First inventory level
810635.fig.001b
(b) Second inventory level
810635.fig.001c
(c) The two items inventory limit cycle
Figure 1: (a) and (b) are the first and the second inventory levels, respectively, of the uncontrolled system, with quadratic rates of supply. (c) is the trajectory of the inventory system in 𝑥 1 𝑥 2 -plane.