power demand是种模型。"A special class of time varying demand is known as power demand and was presented by Naddor (1966). The power demand pattern represents an interesting demand property to show the evolution of the inventory level. It considers the possibility that the demand rate is constant during the inventory cycle, but also allows for situations where the demand units may be primarily withdrawn at the beginning of the period, or situations where a larger portion of demand occurs at the end of the inventory cycle"。