考虑供应不确定性与需求非平稳性的项目调度与材料供应集成优化

在工程建设中，项目调度与材料供应是相互关联和影响的，需要集成管理这两个决策事项.本文考虑供应不确定性与需求非平稳性，以项目总工期提前/延迟奖惩、施工活动开始时间偏离惩罚以及材料库存持有成本之和最小化为目标，研究项目调度与材料供应的集成优化.其中，材料供应主要涉及安全库存设置与分拨决策.该集成优化模型形式复杂，决策变量维度高，难以采用解析方法与传统仿真优化方法进行分析与求解.为此，设计了基于代理模型的优化方法来求解该模型.该方法的核心是采用代理模型来逼近决策变量与优化目标的函数关系，以减少方案评估时的计算成本，提高优化效率.算例分析验证了基于代理模型的优化方法的有效性，并表明项目调度与材料供应集成优化相比于独立决策可以节约成本.

Integrated scheduling and material supply planning under nonstationary stochastic demand and random supply yield

Project schedule and material supply are usually mutual interdependent, and simultaneous planning of these two tasks can improve the project execution costs. This paper develops mode to simultaneously integrating and optimizing the critical planning decisions of project schedule and material supply under nonstationary stochastic demand and random supply yield, in which the material supply planning refers to safety-stock determination and material allocation. The objective focuses on the trade-offs among several costs, such as bonus/plenty in project completion, deviate plenty in baseline schedule and material holding cost. Due to the complex form and high variable dimension, it is difficult to analytically solve the integrated optimization model. Therefore, we adopt the surrogate-based optimization method to cope with this issues, which is a novel simulation method. Compared with the traditional simulation, this method develops a surrogate model to approximate the simulation process. A significant amount of computation time can be saved with this method. Finally, the numerical analysis demonstrates the effectiveness of the surrogate-based optimization method. Results show that the simultaneously optimizing project schedule and material supply plans performs better regarding them as two separate ones.