This research studies lateral transshipment of critical medical items that have low demands. Due to the high prices of medical items and their limited shelf lives, the expirations contribute significantly to the current prohibitively high cost of the healthcare system. Lateral transshipment between hospitals in a medical system provides opportunities to reduce the expiration costs. This paper studies the decision rule for lateral transshipment in a two-hospital system and extends the rule for the multiple-hospital cases. The decision rule takes the myopic best action by assuming no transshipments will be performed in the future. Numerical experiments demonstrate significant cost savings and the decision rule has a small gap from the upper bound of the total saving. The savings are more considerable when the difference of demand rates at different locations is large and the life time of the medical item is not too long or too short.

There are numerous applications of game theory in the analysis of supply chains where multiple actors interact with each other in order to reach their own objectives. In this paper we review the use of non-cooperative game theory in inventory management within the newsvendor framework describing a single period inventory control model with the focus on horizontal interactions among multiple independent newsvendors. We develop a framework for identifying these types of horizontal interactions including, for example, the models with the possibility of inventory sharing via transshipments, and situations with substitutable products sold by multiple newsvendors. Based on this framework, we discuss and relate the results of prior research and identify future research opportunities.

We study risk pooling via unidirectional lateral transshipments between two locations under local decision-making. Unidirectional transshipments can be applicable when cost structures and/or capabilities differ between locations, and it is also a common practice in dual channel supply chains with online and offline sales channels. We show that such a system cannot be coordinated only with varying transshipment prices. The transshipment receiver orders more and the transshipment giver orders less than the respective optimal centralised order quantities. In order to remove this discrepancy, we suggest horizontal coordinationmechanisms by introducing a leftover subsidy for the location providing the transshipments or a shortage subsidy for the location receiving transshipments as well as a combination of shortage and leftover subsidy. Further, we evaluate the impact of network structure by comparing the equilibrium order quantities and profits under the uni- and bidirectional systems as well as a system without transshipments. Since demand correlation is a critical aspect in risk pooling we provide a detailed numerical study to discuss its impact on our findings.

The thesis contributes to the body of knowledge in analyzing and optimizing inventories of multiple stocking locations in a supply chain system. Optimization model is developed for planning inventories with respect to the proposed inventory-pooling strategy. The model is solved under stochastic environment using a Hybrid Genetic Algorithm technique.

La logistique collaborative est récemment devenue un élément important pour beaucoup d'entreprises afin d'améliorer l'efficacité de leur chaîne logistique. Dans cette thèse, nous étudions les possibilités offertes par les problèmes de collectes et livraisons pour améliorer les performances des chaînes logistiques grâce au transport collaboratif. La thèse est inscrite dans un projet européen nommé SCALE (Step Change in Agri-food Logistics Ecosystem). Dans un premier temps, deux métaheuristiques sont proposées et étudiées pour résoudre le problème de collectes et livraisons avec transbordements. Celles-ci sont comparées aux travaux de la littérature et permettent d’améliorer les résultats sur certaines instances. Dans un deuxième temps, un modèle pour un problème de collectes et livraisons (PDVRP) est proposé. Celui-ci est utilisé pour étudier les bénéfices de la collaboration sur le transport. Il est appliqué sur des données générées aléatoirement et sur des données réelles issues du projet SCALE. Enfin troisièmement, un modèle pour un PDVRP particulier est présenté. Dans ce modèle, les marchandises doivent passer par exactement deux points de transbordement entre les points de collecte et les points de livraison. Ce problème est inspiré d'une seconde étude de cas réalisée dans le cadre du projet SCALE. Ceci permet de mettre en évidence l’intérêt de la collaboration et du transbordement dans le domaine du transport de marchandises. / Collaborative logistics have become recently an important element for many companies to improve their supply chains efficiency. In this thesis, we study pickup and delivery problems to improve supply chains efficiency thanks to collaborative transportation. The thesis was part of the European project SCALE (Step Change in Agri-food Logistics Ecosystem). Firstly, two metaheuristics are proposed and studied to solve the Pickup and Delivery Problem with Transshipments. These metaheuristics are compared with literature works and the results of several instances are improved. Secondly, a mathematical model for a pickup and delivery problem (PDVRP) is proposed. This model is used to study the benefits of collaboration on transportation. It is applied on random data and on a case study from SCALE with real data. Finally, a model for a particular PDVRP is presented. In this model, the shipments have to cross exactly two transshipments nodes between their pickup and delivery points. This problem is inspired by a second case study made during the project SCALE. This allows to highlight the importance of collaboration and transshipment in the field of goods transportations.

The highly variable demand of fast fashion causes retailers in the industry to face large uncertainties when allocating initial inventory batches across multiple locations. Further into the selling season, inventory imbalances might arise as an effect of deviations from expected demand. To mitigate these imbalances, retailers can make use of lateral transshipments of inventory from locations with excess stock to those facing the risk of a stockout. Such transshipments require models for determining what and how much to ship as well as when to ship it. This thesis investigates how such a model can be applied on replenishment warehouse level in a fast-fashion retail setting. The research was conducted through a quantitative case study at Hennes & Mauritz (H&M), one of the largest fast-fashion retailers in the world. An appropriate existing transshipment model based on the concept of service level was identified and adjusted to suit the characteristics of H&M. In contrast to the vast majority of models in literature, empirical probability distributions were used for dynamically modelling short-term demand. The proposed model was evaluated and found to suggest transshipments yielding significant revenue increase driven by lowered price reductions. This thesis differs from existing literature by providing a unique case-study of how a transshipment model can be applied in practice and how it performs on empirical data from one of the largest fast-fashion retailers in the world. / Den kraftigt varierande efterfrågan på snabbt mode gör att aktörer i branschen står inför stora osäkerheter vid initiala lagerallokeringar. Längre in i försäljningscykeln kan lagerobalanser uppstå till följd av avvikelser från den förväntade efterfrågan. För att hantera obalanserna kan företag flytta lager från de regioner med lageröverskott till de som i närtid riskerar att få slut i lager. Sådana flyttar kräver modeller för att avgöra vad och hur mycket som ska flyttas samt när det ska flyttas. Detta examensarbete undersöker hur en sådan modell kan appliceras inom branschen för snabbt mode. Studien genomfördes som en kvantitativ fallstudie i samarbete med Hennes & Mauritz (H&M), en av världens största aktörer inom snabbmodebranschen. En lämplig existerande modell som baseras på konceptet om servicenivå identifierades och anpassades efter H&M:s egenskaper. Till skillnad från majoriteten av modeller i literature användes empiriska sannolikhetsfördelningar för att dynamiskt modellera kortsiktig efterfrågan. Den föreslagna modellen utvärderades och visades föreslå flyttar som genererar signifikanta intäktsökningar drivet av lägre prisnedsättningar. Denna studie skiljer sig från existerande litteratur genom sitt bidrag med en unik fallstudie av hur en modell för lagerflyttar kan appliceras i praktiken samt hur den presterar på empirisk data från en av världens största snabbmodeaktörer.