فهرست نشریات علمی دسترسی آزاد ایران

The Two-Echelon Location-Routing Problem with Simultaneous Pickup and Delivery (2E-LRPSPD) is a critical challenge in logistics and transportation, requiring the optimal placement of primary and secondary warehouses and the routing of vehicles to satisfy both pickup and delivery demands. The problem becomes more complex under uncertainty, as delivery and pickup demands can fluctuate dynamically. Traditional deterministic approaches often fail to capture this variability, limiting their applicability in real-world scenarios. In this study, we propose a novel fuzzy-based framework to address the 2E-LRPSPD under uncertain demand. A Mixed-Integer Linear Programming (MILP) model is developed to represent the two-echelon network, incorporating simultaneous pickup and delivery under uncertain conditions. To efficiently solve this complex model, we implement a Variable Neighborhood Search (VNS) algorithm, capable of exploring diverse solution spaces and generating high-quality solutions. The proposed approach is validated through extensive numerical experiments on benchmark instances and sensitivity analyses, demonstrating its effectiveness and superiority over existing methods in terms of solution quality and computational efficiency.