Resilient Supply Chain Network Design Under Uncertain Environment

For the past few years,the supply chain has been improved from several aspects,driven by various factors,such as the rapid development of economic globalization,the reaffirmation of sustainable development,the emergence of modern technologies,and the introduction of new concepts such as new retail.Several new terms have emerged,global supply chain,green supply chain,digital supply chain,and smart supply chain.The development has characterized supply chain with longer chains,wider geographic area,more complex structure,and more dynamic adjustment.Naturally,there are more and more uncertain factors during the operation of supply chain.These factors may disturb supply chain in varying forms and degrees.Driven by such challenges,how the supply chain can withstand unexpected events and return to its original state of operation quickly after being disturbed has drawn widespread attention from academics and practitioners.This ability is commonly characterized as the resilience of the supply chain.And some scholars also highlight the need to take resilience into account in the planning stages since supply chain configuration is costly and hard to reverse once being built.So this paper addresses resilient supply chain network design problem under uncertain environment from the following aspects.This paper firstly addresses supply chain network design problem under disruption and operational risks.For such a problem,we adopt an integrated approach and a hierarchical approach to present two uncertain programming models.The presented models adopt the scenario-based approach to model the disruption scenarios,each of which specifies a set of facilities that are disrupted simultaneously.Moreover,influences of disruption risks on the supply chain are reflected by the capacity loss of facilities and cost increase.And irregular changes in the market are quantified as the increase in demand.These parameters are modeled as uncertain variables using uncertainty theory since the historical data is nonexistent.Besides,to control the risk,we introduce a risk constraint by restraining the difference between the expected value and Va R of the rate of unmet demand.The study shows that disruption risks and irregular changes in the market do affect the strategic decisions of the supply chain.And the risk constraint can control the risk and losses posed by unpredictable events,at the expense of higher investment.Using the same approaches to deal with disruption and operational risks,we next attempt to enhance the resilience of the supply chain.For this purpose,proactive strategies,such as facility fortification and extra capacity are introduced.Facility fortification can improve the ability of the supply chain to prevent risks.Extra capacity is conducive to mitigate the pressure of insufficient supply capacity caused by lost capacity and increase demand.Unfortunately,these strategies also cause unnecessary redundancy.To control redundancy,we introduce a function to quantify redundancy based on the supply capacity and production capacity of the supply chain.The study shows that these two proactive strategies can reduce the total cost and redundancy of the supply chain while improving the resilience of the supply chain.And the combination of the two strategies is superior to the single strategy.Besides,disruption and operational risks will affect the decisions of facility location and proactive strategy.The higher the uncertainty,the stronger the defense capability should be.In addition to proactive strategies,we also consider responsive strategies to improve the ability of the supply chain to respond to risks.To this end,we put forward out-sourcing and emergency facilities and capacity expansion strategies.Combining proactive and responsive strategies,we consider the risk preference of decision-makers to present three uncertain programming models,which minimizing pessimistic value,expected value,and optimistic value of total costs,respectively.These models can provide the value range of the total costs.The study shows that the presented responsive strategies are effective to improve the service level of the supply chain during supply disruptions.And outsourcing strategy is superior in reducing cost,while capacity expansion strategy is superior in improving service level.The combination of proactive and responsive strategies is better than the single strategy.Finally,this paper attempts to verify whether the recovery ability of the supply chain affects the optimal decisions of the supply chain.To solve this problem,we consider the recovery time window and adopt an integrated decision-making approach to present a two-stage programming model,which identifies the decisions of design,response,and recovery plans whilst minimizing total costs.To be more realistic,the time delay of responsive strategies and recovery actions are considered in the presented models.Besides,we attempt to quantify the resilience of the supply chain.For this purpose,the metric of the ratio of supply capacity before and after disruptions is adopted.Based on this metric,we construct three resilience functions according to the prevention,response,and recovery ability of the supply chain.Then the uncertain programming models are proposed to trade off the cost and resilience of the supply chain.The study shows that the time delay of recovery actions can affect the strategic decisions of the supply chain.Longer time delay suggests more prevention ability of supply chain.And,the response time of the responsive strategy only affects the total cost of the supply chain.Besides,the resilience constraint highlighting the prevention ability is stronger than the constraint of comprehensive ability.In summary,this paper addresses resilient supply chain network design problem under uncertain environment based on several decision criteria by using different decision-making approaches.The study constructs functions to control risk,redundancy,and resilience,respectively.The influence of unpredictable events and recovery actions on the decision-making of the supply chain is discussed.The effectiveness of resilience strategies to improve the resilience of the supply chain is verified.It is expected that the research results will provide some managerial and practical insights for enterprises in the application.