The efficient transportation network has made possible the lowering of the level of safety stock with its resultant reduction in inventory carrying cost.

有效的运输网络使降低安全库存水平，减少库存持有成本成为可能。

But the thesis only involves inventory carrying cost and order setup cost, not includes transportation cost.

但是文献只涉及订货成本、储存成本，并没有考虑运输成本。