BI-LEVEL PROGRAMMING FOR EMERGENCY BLOOD TRANSSHIPMENT-ALLOCATION CONSIDERING SUBSTITUTION AGAINST PUBLIC HEALTH EVENTS

The emergence of major public health crises, such as the Covid-19 pandemic, has significantly impacted the blood supply chain. We developed a bi-level programming model for emergency blood transshipment-allocation under this scenario, based on a cross-regional blood transshipment allocation network with a hierarchical structure. Our model considers emergency allocation, blood acceptability limits, blood type substitution relationships, hierarchical relationships among scheduling networks, and cross-regional and multi-modal transportation. The upper-level objective of our model is to minimize the total system cost, which includes shortage and substitution penalties. The lower-level objective is to maximize blood allocation satisfaction while considering demand urgency and blood type substitution. A primal-dual algorithm based on complementary relaxation conditions is established to solve the transformed model. The efficacy of our proposed model and solution strategy is validated through numerical calculations.