Management of mobile resources in Physical Internet logistic models

International audienceThis paper deals with the concept of a "Physical Internet", the idea of building large logistics systems like the very successful Digital Internet network. The idea is to handle mobile resources, such as containers, just like Internet data packets. Thus, it is possible to use the principles of encapsulation and routing to optimize the freight. The problem is that mobile resources, such as containers, are not quite similar to data packets, because they are real and not dematerialized. Thus the handling and the storing of mobile resources, such as containers, will create imbalances in the logistics network, leading to starvation or overstocking of logistic network nodes. We propose in this paper a study addressing this problem leading to some solutions

Minimum Spanning Trees in Weakly Dynamic Graphs

International audienceIn this paper, we study weakly dynamic undirected graphs, that can be used to represent some logistic networks. The goal is to deliver all the delivery points in the network. The network exists in a mostly stable environment, except for a few edges known to be non-stable. The weight of each of these non-stable edges may change at any time (bascule or lift bridge, elevator, traffic congestion...). All other edges have stable weights that never change. This problem can be now considered as a Minimum Spanning Tree (MST) problem on a dynamic graph. We propose an efficient polynomial algorithm that computes in advance alternative MSTs for all possible configurations. No additional computation is then needed after any change in the problem because the MSTs are already known in all cases. We use these results to compute critical values for the non-stable weights and to pre-compute best paths. When the non-stable weights change, the appropriate MST may then directly and immediately be used without any recomputation

A Proposal for an Open Logistics Interconnection Reference Model for a Physical Internet

International audienceThis paper presents a New Open Logistics Interconnection (NOLI) reference model for a Physical Internet, inspired by the Open Systems Interconnection (OSI) reference model for data networks. This NOLI model is compared to the OSI model, and to the Transmission Control Protocol/Internet Protocol (TCP/IP) model of Internet. It is also compared to the OLI model for a Physical Internet proposed by Montreuil. The main differences between the presented NOLI model and all the other models named above are in the appearance of definitions of physical objects in different layers and not just the lowest one. Also, the NOLI model we present locates the containerization and de-containerization operations in the topmost layer, and not in the layer below as does the OLI model. Finally, the NOLI model is closer to the TCP/IP and OSI models than the OLI model, keeping the integrity of the Link Layer that the OLI model divides in two layers, and keeping separate the Session and Transport OSI Layers that the OLI model unites in just one layer

Working Modes with a Declarative Modeler

International audienceThis paper presents the point of view of a designer about declarative modelers. We propose a model of this point of view. Our approach is based on the work we have done to develop some of our declarative modelers. It takes into account the main functions used by a designer in these modelers. We explain also the scene-building process and we present working processes that can be used with those modelers

Wear mechanisms of WC-Co drill bit inserts against alumina counterface under dry friction: Part 2 — Graded WC-Co inserts

The tribological behaviour of innovative graded cemented carbide inserts were studied by using a rotary tribometer and abrasive alumina counterfaces. This work completes the study made on commercial inserts with homogeneous cobalt content. Inserts with three types of graduation processes were considered: inserts with borides WCoB phases, imbibed inserts and inserts combining both processes (i.e. inserts with reactive imbibition). Physicochemical and mechanical measurements show that the WCoB phases increase the hardness towards the active surface and the imbibition increases the insert core fracture toughness. The wear tests indicate that the boride phases lower the friction coefficient. In addition, as for the commercial inserts, cemented carbide volumes with higher cobalt content also reduce the friction coefficient. Concerning the wear results, the boride phases improve the abrasion resistance. By applying a third body approach, the WCoB phases limit the introduction of cobalt binder in the source flow, the cohesion of alumina particles in the internal flow and the formation of an abrasive paste in the contact. The imbibition process, where the cobalt migration is controlled, does not affect the wear resistance by avoiding a cobalt enrichment of the cemented carbide near the active surface

Du courrier des lecteurs aux forums de discussion sur l’internet : retour sur la notion de genre

Les forums de discussion sur l’internet véhiculent des échanges originaux par rapport aux conversations en face-à-face et aux écrits sur support « papier ». Pour autant, des formes d’écrits plus traditionnelles, comme par exemple les courriers des lecteurs, présentent de nombreux points communs avec les messages en circulation sur les forums de discussion. Afin d’illustrer cette proximité, on prend appui sur une revue anglaise de jeux de reconstitutions historiques, Lone Warrior, dont les numéros collectés (datant de 1982) présentaient, il y a plus de vingt ans déjà, des caractéristiques formelles proches de ce que l’on observe actuellement sur l’internet. Après avoir mis au jour ces ressemblances, on compare les dispositifs énonciatifs en amont des réalisations textuelles, en interrogeant les genres « courrier des lecteurs » et « forums de discussion ». Puis on valide l’hypothèse que le caractère très spécialisé du magazine pris en exemple apparente particulièrement les échanges composant son courrier des lecteurs à ceux rencontrés dans les forums de discussion. Cela autorise une réflexion sur les notions de communauté discursive et de genre, à la lumière des variations de supports