Formal DEVS modelling and simulation of a Flow-Shop relocation method without interrupting the production

International audienceThis paper presents an organisational method to keep the production going during the removal of a flow-shop. Assume a flow-shop system is to be moved on a new site and its production has to continue, our method can be applied to follow requests for the removal period. The method works as follows: we segment the removals in groups of machines and move them ones after the others. This method can be successfully executed provided that a prime condition is met: envisaging sufficient stocks’ plug between each group. The role of the latter stocks is to ensure operations’ production continuity between the old and the new site, when the non-operational group is being removed. Removal is then renewed until the whole line is moved and is operational on the new site. To validate this approach, we have used simulation and developed a model of the flow-shop according to coupled DEVS formalism. Our model enables to segment a production line. As a consequence, we can simulate the sequential displacement of machines’ groups towards the new site. Among the solutions suggested, those starting with the final group (finished products) and while finishing with the first group are much more effective. In this paper, we present and discuss some simulation results of an industrial case study. The results demonstrate the compared effectiveness of various strategies of removal, and make possible for the industrialist to envisage a good estimated project management

Lookahead Computation in G-DEVS/HLA Environment

International audienceIn this article, we present new methods to evaluate lookahead of DEVS/G-DEVS federates participating in a HLA federation. We propose first an algorithm to compute the lookahead according to the current state of a DEVS/G-DEVS model. This solution is designed for models with lifetime function depending on one state variable. Then, we extend this computation to models with lifetime functions defined with several state variables. We use the Dijkstra graph theory search to compute the different values of state variables and a mathematical function analysis to determine the lookahead for the model states. Finally, we illustrate with an example how this solution extends the range of DEVS/G-DEVS models that can be involved into distributed simulations and we present some simulation results

Another way to manage supply chains: holonic and multicriteria approach

International audienceToday’s suppliers are challenged to deliver quality to their customers. Managers need to create and sustain internal systems and controls to ensure that their customers-focused strategies are being implemented. Many companies increasingly turn to their core activities to improve their reactivity and to manage their costs. This paper proposes an approach for self-organized control of relations between companies in which all the members of a partnership negotiate to guarantee good quality connections between customers and suppliers. Each partner is associated with a decision- making entity named “Autonomous Control Entity” (ACE) through which he can evaluate his performance. The integration of these ACEs into a holonic control system is presented. Operations of an ACE have been modelled through the Discrete EVent system Specification (DEVS) formalism. Then, the validation of such a control system for a self-organized logistic partnership network was done through a distributed High Level Architecture (HLA) simulation environmen

Environnement G-DEVS/HLA pour la simulation distribuée de systèmes de production multiprocessus

International audienceThis paper presents a simulation environment for manufacturing systems integrating control processes and operational processes. From the operational processes specification according to the JIS Z 8206 norm and from the control processes as Workflows standards, distributed G-DEVS models are generated. At first, the transformation of a process in G-DEVS models is described. Then, the implementation of a global simulation of the set of these models via an HLA architecture allowing interconnection and interoperability between the model components is presented. An illustration of the use of this environment is given in the microelectronic field. We conclude by the application of this approach to the study of the synchronizations between production lines and to the implementation of coupling between simulation and reality

Customers-Suppliers Relationship Management in an Intelligent Supply Chain

International audienceOutsourcing is leading to more and more complex industrial organizations. This can be attributed to the fact that several decisions centres interact. As a consequence, changes in customers-suppliers relationships can be noticed. In recent years, these relations have strongly evolved to lead to better internal management of each partner and a better general performance to satisfy customers. These evolutions created a new approach of the relations between companies, called ‘industrial partnership’, in the form of a network. Networks induce a need at customers-suppliers relation control level. The contribution and participation of each of the partners are thus fundamental to make Supply Chain Management (SCM) a successful project. The control system of each actor partner must thus be adaptable enough to satisfy the production requirements. Our contribution to the improvement of customers-suppliers relationship is a decentralized self-organized control model. In this model, the decision system manages a group of actors’ operations who are in a partnership (part of companies network). In this paper, we, particularly discuss a process for the evaluation of the suppliers network

Integration of a Flat Holonic Form in an HLA Environment

International audienceManagers need to create and sustain internal systems and controls to ensure that their customer focused strategies are being implemented. Companies are currently in a spiral of permanent optimization. Accordingly, many companies turn to their core activity. In this framework, one notices the development of the concept of “industrial partnership”. In this context and to control the customer–supplier relationships (CSR), we proposed a self-organized control model in which all partner entities (customers/suppliers) negotiate to guarantee good quality connections between customers and suppliers. This means meeting customer expectations as closely as possible and respecting supplier capacities. In this proposal, self-organized control is characterized more precisely by an organizational architecture of the flat holonic form type. This flat holonic form is based on the concept of autonomous control entity (ACE). The holonic architecture, the behaviour of an ACE, the interaction mechanisms between ACEs and the self-evaluation supplier process are presented, and then the modelling of ACEs using discrete event system specification (DEVS) is described. An implementation of the simulation of such a system was done via a distributed simulation environment high level architecture (HLA). A case study illustrating the proposed approach is presented

Abstractions d'évènements Discrets de Systèmes Dynamiques

National audienceno abstrac

An introduction to Timed Sequential Machines

International audienceno abstrac

An introduction to Timed Sequential Machines

International audienceno abstrac

An introduction to Timed Sequential Machines

International audienceno abstrac