Rochdi Sarraj

Interconnected logistic networks and protocols: simulation-based efficiency assessment

Logistic networks intensely use means of transportation and storage facilities to deliver goods. However, these logistic networks are still poorly interconnected and this fragmentation is responsible for a lack of consolidation and thus efficiency. To cope with the seeming contradiction of just-in-time deliveries and challenging emissions targets, a major improvement in supply networks is sought here. This new organisation is based on the universal interconnection of logistics services, namely a Physical Internet where goods travel in modular containers for the sake of interconnection in open networks. If from a logical point of view, merging container flows should improve efficiency, no demonstration of its potential has been carried out prior to the here reported research. To reach this potentiality assessment goal, we model the asynchronous shipment and creation of containers within an interconnected network of services, find the best path routing for each container and minimise the use of transportations means. To carry out the demonstration and assess the associated stakes, we use a set of actual flows from the fast-moving consumer goods sector in France. Various transportation protocols and scenarios are tested, revealing encouraging results for efficiency indicators such as CO2 emissions, cost, lead time, delivery travel time, and so forth. As this is a first work in the field of flows transportation, the simulation model and experiment exposes many further research avenues.

Perspectives of inventory control models in the Physical Internet

We reveal a new research field of inventory management in the Physical Internet Network.We identify the particularities of inventory management in the Physical Internet Network.We define the initial criteria for selecting replenishment point in the Physical Internet Network.We assess the performance of the criteria under (Q,R) policy via simulation study.The results show that criteria have very different performance and sensitivity to the logistics cost. Classical supply chain design relies on a hierarchical organization to store and distribute products over a given geographical area. Within this framework, a stock shortage affects the entire downstream section of the supply chain, regardless of the stocks kept in other locations. With the implementation of the Physical Internet (PI) approach, of which the aim is to integrate logistics networks into a universal, interconnected system, inventories can be divided among shared hubs that serve the market and allow for Source Substitution. This contribution measures the impact of such an organization on inventory levels and costs, with service level being set as a constraint. The analysis focuses on the resource levels (transportation and inventory) required by the current supply model and by the Physical Internet system to serve a market with a (Q,R) stock policy. Starting with two supply models and with the definition of cost models, as well as inventory policy, the work is based on computer simulation. The analysis tested three different categories of criteria to allow dynamic source selection when an order is placed: Source Substitution, Minimum Ratio and Minimum Sum. Source Substitution, one of the simplest criteria, was determined to be the most efficient and stable according to different scenarios. The main intent of this paper is to define the new research question related to inventory management in a Physical Internet Network and to provide a view of how the PI affects traditional inventory control policies.