在MTO-MTS混合生产模式下,合理协调生产和库存是合同计划需要解决的关键问题.本文将多级库存匹配引入合同计划,同时考虑半成品库存、成品库存和多工序生产,以最小化合同的库存匹配费用、提前/拖期惩罚、交期惩罚、产能均衡惩罚和合同取消惩罚为目标建立联合优化数学模型.基于该模型,构造了PSOReM算法,采用重匹配协同策略提高搜索空间的全局性,改进粒子群算法的求解性能.通过仿真实验确定相关参数,采用某著名钢厂的多组算例分析了多级库存匹配策略对库存管理和生产计划的协调作用,并验证了本文算法的有效性.%With the global economic integration and the change of consumer demand,iron-steel enterprises need to reform and upgrade the traditional production models through advanced management modes.In order to solve the contradiction between improving the market service level and ensuring the economical efficiency of the internal production,enterprises have to consider applying both make-to-order (MTO) and make-to-stock (MTS) production modes to establish a hybrid MTO-MTS management framework,which becomes an inevitable trend for the development of the iron-steel industries.Order planning is the core area in the production planning management system of iron-steel enterprises.It combines both MTO and MTS modes effectively,considers comprehensively the inventory management and production planning,operates the various production processes,and determines whether production can be completed smoothly and efficiently.As an absolutely necessary part of the order planning,inventory matching can match the remaining inventory with the order to be delivered in the current period,thus improving the ability of timely delivery,and reducing stock funds and venues caused by inventory.However,too much inventory matching,especially the lossy matching that the products of higher steel grade being selected to meet requirement of lower grade order,may not only lead to high matching costs,but also the remaining small units resulting in increased production costs.In contrast,too little inventory matching could lead to excessive backlog of inventory,thereby increasing inventory costs.Thus,how to match the inventory is a key factor that affects the results of order planning.In this paper,we introduce the multi-level inventory matching into order planning,consider order production planning of multiple processes,and order inventory matching of both finished and unfinished products at the same time.Under the premise of satisfying inventory matching constraints,production capacity constraints,production time sequence constraints,and synergistic constraints of inventory matching and production,this paper constructs a mixed integer programming mathematical model with the goal of jointly optimizing the cost of earliness/tardiness penalty,tardiness penalty within delivery time window,production cost,inventory matching cost,and order cancelation penalty.In view of the above model,it is difficult to optimize the multi-level inventory matching and multi-process production planning at the same time by using the general Particle Swarm Optimizer(PSO) algorithm.Therefore,this paper designs an improved PSO algorithm based on rematch coordination mechanism (PSOReM) to deal with the problem.Specifically,the rematch coordination mechanism includes two parts,re-match policy for both finished and semi-finished products inventory.Each time before using the PSO algorithm to optimize the production planning,the rematch coordination mechanism adjusts multi-level inventory matching scheme according to the matching cancellation probability and the re-matching probability in order to change the searching space of the next round of PSO,thus improving the global optimization ability of the algorithm.On the basis of the further optimization of production planning by PSO,it is important to rematch the coordination mechanism.On the whole,the PSO algorithm is mainly responsible for optimizing production planning,while the rematch coordination mechanism switches the orders between the production planning and inventory matching scheme according to certain proportion,and adjusts the configuration of the order set on order planning,gradually expanding the search space in order to achieve a collaborative optimization for both inventory matching and production planning.The simulation experiment is designed to test the order sets with different scales.The experimental results show that applying multi-level inventory matching into order planning can enrich the route selection of order delivery and play the role of inventory surplus material and production capacity.The production and management idea combines MTO and MTS.In addition,particle swarm optimization algorithm by re-matching the proposed coordination mechanism (PSOReM) can improve the global search ability of the algorithm during the process of multi-level inventory matching and joint optimization of multi-process production planning,thereby improving the collaborative role of inventory and production.
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