Studying Two-stage Supply Contracts Problem With Uncertain Demand

Supply contracts have been a hot research topic in supply chain management.This disser-tation deals with the contract problem from the perspective of distributors.Considering an op-timal purchase plan,distributors obtain the maximum profit under uncertain demands.Because commodities have theirs fixed production cycle,we need to book them in advance.The uncer-tainty of demands may cause stockout or inventory backlog if ordering commodities blindly.The options-futures contract is employed to reduce the risk from the uncertain demand,which will be achieved by twice decision-making in time horizon.The initial decision is to decide the quantities of ordering futures and options;and the recourse decision is to decide the quantities of exercising options after demands are realized.This strategy is very effective to reduce the risks faced by distributors.The uncertainty contains randomness and fuzziness.In the case of random uncertainty,a two-stage bi-objective mean-standard deviation model is established,where the mean profit and the standard deviation of profit are two objectives.Using the weight coefficient method to deal with the bi-objective,decision makers can adjust the share of profit and risk on the basis of their risk preference level.The two-stage bi-objective model is simplified into determinis-tic single-stage single objective models by using stochastic optimization method under some common distributions.The single-stage single objective models can be solved by commercial optimization software directly.In the case of hybrid uncertainty,the uncertain demand is char-acterized by random fuzzy variable.A two-stage expected value model is established.The two-stage model is simplified into equivalent deterministic single-stage models by using ran-dom fuzzy optimization method under some common distributions.The single-stage models can be solved by commercial optimization software directly.Finally,numerical examples and parameter analysis are presented to illustrate that the proposed models are effective.The main contributions of this paper include the following five aspects:(1)A two-stage bi-objective stochastic optimization model and a two-stage expected value random fuzzy opti-mization model for supply contracts problem are established under two types of uncertain de-mands;(2)In stochastic environment,maximizing the profit and minimizing the risk,the most concerned two objectives of decision makers,are considered in the proposed model.Using the weight coefficient method,we deal with the bi-objective optimization model;(3)The calcu-lation steps for the expected value of random fuzzy variables' function are designed,and the analytic expressions of expected profit are derived under some special distributions;(4)Under wild assumptions,the proposed two-stage models are transformed into the tractable equivalent single-stage models;(5)Numerical experiments illustrate that the proposed models are effec-tive.