Research On Bulk Material Inventory Management For Major Projects

Some bulk materials are usually required by multiple activities with massive demand,and constitute a large proportion of total budget of the project.The timely,quality,quantitative,and economic organization and management of material supply can help achieve the schedule,cost,and quality performance of the project.In some large-scale projects,a centralized mode is implemented to address the material supply issues.Under this mode,the material inventory is also controlled in a centralized way.In this centralized inventory system,the cycle inventory and safety stock will go down.But influenced by the demand nonstationary and supply uncertainy,there still exist some challenges for the centralized inventory system.Motivated by the observations in project practices,this thesis will investigate the safety stock determination,material allocation policies and incentive schemes by using the simulation optimization and mechanism design methods.The main research works are as follows:Firstly,we consider the nonstationary stochastic demand and random supply yield,and develops general safety-stock determination approaches under both the base-stock replenishment policy with unit and nonunit review period.The main process of safety-stock determination approaches can be summarized as three steps,which are deriving the inventory balance equation,building a coverage random variable and using the fixed-point iteration method is used to calculate the safety stock under the predefined nonstockout probability.As formulating the complete information of outstanding orders,the proposed approaches can solve the supply and demand matching problem by an accurate safety stock level.A numerical analysis demonstrates a considerable inventory decrease of the safetystock approaches when compared with the DOS rule.Secondly,we study the material allocation policies by using a simulation optimization method.This thesis develops a framework to model inventory replenishment and allocation decisions jointly,and propose five allocation policies on the basis of the activity feature information(e.g.,schedule,cost,and demand),which are chedule-based,cost-based,demand-based,schedule-cost-based,and schedule-demand-based policies.Meanwhile,a new quantitative description indicator of project network,path difference(PD),is proposed.Based on a large set of fictitious project networks with different PD,a computational analysis is conducted to make detailed interpolicy comparisons and find the most appropriate policy for project networks with different characteristics.Thirdly,we investigate the integrated project scheduling and material supply planning under nonstationary stochastic demand and random supply yield.This thesis develops model to simultaneously 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 solve the integrated optimization model by traditional simulation optimization method.Therefore,a surrogate-based optimization method is adopted to cope with this issues.A significant amount of computation time can be saved with this method.The numerical analysis demonstrates the effectiveness of the surrogate-based optimization method and the integrated optimization of project schedule and material supply plans.Finally,we investigate the incentive schemes for centralized material planning and allocation with asymmetric information.The cases of having prior information and no prior information about the demands are considered in the incentives problems.Under the case of having prior information,an incentive scheme is designed on the basis of Groves payment rule.This Groves incentive scheme is truthful,efficient,and voluntary-participation under both the priority allocation and proportional allocation policies.Under the case of no prior information,two incentive schemes are designed on the basis of proper scoring rule.the first scoring-rule-based incentive scheme is truthful,efficient,and participatory only under the priority policy,while the second scoring-rule-based incentive scheme can do that under both the two allocation policies.The results demonstrate that the prior information is not necessary for coordinating the construction supply chain.Even without prior information,the coordination issue can be solved by using the scoring rule-based incentive schemes.