Humanitarian aid agencies usually resort to inventory prepositioning to mitigate the impact of disasters by sending emergency supplies to the affected area as quickly as possible. However, a lack of replenishment opportunity after a disaster can greatly hamper the effectiveness of the relief operation due to uncertainty in demand. In this paper, a prepositioning problem is formulated as a two-period newsvendor model where the response phase is divided into two periods. The model acknowledges the demand to be uncertain even after the disaster and utilises the Bayesian approach to revise the demand of the second period. Based on the revised demand, an order is placed at the beginning of the second period to be replenished instantaneously. A two-stage solution methodology is proposed to find the prepositioning quantity and post-disaster replenishment quantity, which minimise the total expected costs of relief operations. A numerical example is presented to demonstrate the solution methodology, and sensitivity analysis is performed to examine the effect of model parameters. The results highlight the indifferent characteristics shown by the replenishment quantity with the variation in model parameters.

人道主义援助机构通常采用库存预置的方式，通过尽快向受灾地区发送紧急物资来减轻灾害的影响。然而，由于需求的不确定性，灾后补给机会的缺乏会极大地阻碍救援行动的有效性。在本文中，一个前置问题被表述为一个两阶段报童模型，其中响应阶段被分为两个阶段。该模型承认即使在灾难发生后需求也是不确定的，并利用贝叶斯方法来修正第二期的需求。根据修改后的需求，在第二期开始时下订单，即时补货。提出了一种两阶段解决方法来寻找预置数量和灾后补给数量，从而使救援行动的总预期成本最小化。给出了一个数值例子来演示求解方法，并进行敏感性分析来检查模型参数的影响。结果突出了补货数量随模型参数变化所表现出的无差异特征。