题目：
1. Multi-Sourcing Supply Network Design: Two-Stage Chance-Constrained Model, Tractable Approximations, and Computational Results
2. Models for Effective Deployment and Redistribution of Bicycles within Public Bicycle-Sharing Systems
主讲人：国家自然科学基金委2015年杰青、东南大学舒嘉教授
时间：2016年5月24日（星期二）10:00-11:30
地点：交通运输学院211室
讲座摘要：
1. Multi-Sourcing Supply Network Design: Two-Stage Chance-Constrained Model, Tractable Approximations, and Computational Results
In this paper, we study a multi-sourcing supply chain network design problem, in which each retailer faces uncertain demand and can source products from more than one distribution center (DC). The decisions to be simultaneously optimized include the locations and the inventory levels of DCs, the set of DCs serving each retailer, as well as the amount of shipment from DCs to retailers. We propose a nonlinear mixed integer programming model with a joint chance constraint describing a certain service level. Two approaches, namely, a set-wise approximation and a Linear Decision Rule based approximation, are constructed to robustly approximate the service level chance constraint with incomplete demand information. Both approaches yield sparse multi-sourcing distribution networks, which are effective in matching uncertain demand using on-hand inventory and hence successfully reach a high service level. We show through extensive numerical experiments that our approaches outperform other commonly adopted approximations of the chance constraint.
2. Models for Effective Deployment and Redistribution of Bicycles within Public Bicycle-Sharing Systems
We develop practical OR models to support decision making in the design and management of public bicycle-sharing systems. We develop a network flow model with proportionality constraints to estimate the flow of bicycles within the network and the number of trips supported, given an initial allocation of bicycles at each station. We also examine the effectiveness of periodic redistribution of bicycles in the network to support greater flow, and the impact on the number of docks needed.
We conduct our numerical analysis using transit data from train operators in Singapore. Given that a substantial proportion of passengers in the train system commute a short distance --- more than 16% of passengers alight within 2 stops from the origin --- this forms a latent segment of demand for a bicycle-sharing program. We argue that for a bicycle-sharing system to be most effective for this customer segment, the system must deploy the right number of bicycles at the right places, as this affects the utilization rate of the bicycles and how bicycles circulate within the system. We also identify the appropriate operational environments in which periodic redistribution of bicycles will be most effective for improving system performance.