Noureddine Zerhouni

A new industrial cooperative tele-maintenance platform

Abstract With the maturation of new telecommunication technologies, the industrial enterprises wants to integrate the advances to activate on site interventions of experts and then reduce the machines inactivity time. We propose a hardware and software solution allowing us to make a cooperative tele-maintenance: the maintenance staff can do the work remotely and also in collaboration with other experts (Cooperative Work). We emphasize network aspects (heterogeneity, dynamism) and cooperating members mobility for maintenance action achievement. The system we propose allows us to increase availability, mobility, yield and quality and to reduce the costs of equipment failures. In this paper, we show how computer innovative technologies and industrial maintenance techniques combination can offer new uses.

On the control of manufacturing lines modelled by controlled continuous Petri nets

We present a new methodology to study the control of a class of discrete event dynamic systems, opened manufacturing lines and closed manufacturing lines. Our contribution is based on the controlled variable speed continuous Petri net model. The computation of the control variables is made using a classic constrained optimization method. The resulting control solution is used to guide the real system behaviour. Some properties linked to the accessibility problem of the reference input are given. Through illustrative examples, the practical application of this approach issue will be made prominent

A New Contention Access Method for Collision Avoidance in Wireless Sensor Networks

In this paper, we present a new contention access method for scalable wireless sensor networks. In these networks, the traffic levels are often variants, particularly in monitoring applications. Sensors do not regularly have much data to send. However, when an event occurs, every sensor in a given area will send its alert to the access point simultaneously. Hence, this network suffers a huge number of communications at the same time. In fact, at an instant, only one transmission is permitted among interfering nodes. If there are more than two transmissions at the same time, there will be a collision. Therefore, this variant communication of wireless sensor networks leads to an increase in collision and energy consumption. Traditional wireless network uses an exponential back-off scheme to react to collision. However, this scheme is designed for traditional wireless networks and is not well adapted to wireless sensor networks. Our proposal uses a dynamical change of channel access probability which can reduce the number of contention times and collisions. Moreover, it can be applied in any existing MAC protocol of wireless sensor network.

Cooperative systems modeling, example of a cooperative e-maintenance system

Cooperation is an efficiency factor in many activities like design, medicine or maintenance. Several researches try to optimize cooperation activity by using tools or algorithms designed to enhance human interaction. Few researches are made on conceptual cooperation modeling. However, industrials want to compare different algorithms, organizations or cooperation modes. It is also useful to represent these systems in order to simplify design operations. We proposed our cooperating systems modeling in previous work of D. Saint-Voirin, C. Lang, and N. Zerhouni (2003). This one provides a simulation approach to answer this needs. In this paper, we present an application of our modeling principles on an existing e-maintenance system. This system is part of our work on the European PROTEUS project [ITEA 01011, http://www.proteus-iteaproject.com/] by M. Thron, J.P. Thomesse, X. Reboeuf, C. Lang, E. Garcia, J. Szymansi, T. Bangemann (2003). By using these modeling principles, industrials should be able to represent and simulate their remote maintenance systems in order to optimize them.

Structure theory of choice-free petri nets based on eigenvalues

Abstract Choice-free are a class of Petri nets where structural conflicts are forbidden. They are well-suited for modeling concurrent systems with bulk services and arrivals. A new approach, based on eigenvalues, for the study of some structural properties of Choice-free Petri nets is given in this paper. The structural results follow from the computation of eigenvalues of a square matrix with nonnegative off-diagonal elements, known as an M -matrix, obtained by a transformation of the classical incidence matrix. Theorems on M -matrices are used in this paper to prove structural boundedness, liveness, repetitiveness, conservativeness, consistency, and well-formedness of Choice-free Petri nets.

A low latency MAC scheme for event-driven wireless sensor networks

In this paper, we present a low latency media access control scheme which we call LLMAC (Low Latency MAC) for event-driven wireless sensor networks (WSN). In this kind of WSN, sensors do not regularly send data to the sink. They send a burst data only when there is an event in the monitoring area. It takes time for this burst data to arrive to the sink. Normally, these events are critical and we hope to obtain the information on the event in the shortest delay. Hence, the latency is considered to be a crucial requirement in event-driven WSN contrary to the traditional wireless networks where the fairness is the most important requirement. Our proposal LLMAC makes a trade-off between fairness and latency in order to offer a shorter latency transmission when certain events happen. The performance evaluation shows that our proposal reduces the latency in comparison to existing MAC protocols.

Over-hearing for Energy Efficient in Event-Driven Wireless Sensor Network

In this paper, we introduce a new energy efficient medium access control (MAC) protocol for event-driven sensor networks. The event-driven wireless sensor networks do not often have much data to send. When an alarm occurs, many sensors in the network send the same message at the same time. These redundant communications lead to an energy waste due to many transmissions of redundant data and collisions in the network. By using over-hearing message, we propose a new method to solve this problem in order to save energy and to maximize the lifetime of the sensor networks

Cooperative Systems Modeling, Example of a Cooperative e-maintenance System

Cooperation is an efficiency factor in many activities like design, medecine or maintenance. Several researches try to optimize cooperation activity by using tools or algorithms designed to enhance human interaction. Few researches are made on conceptual cooperation modeling. However, industrials want to compare different algorithms, organizations or cooperation modes. It is also useful to represent these systems in order to simplify design operations. We proposed our cooperating systems modeling in our previous work [12]. This one provides a simulation approach to answer to this needs. In this paper, we present an application of our modeling principles on an existing e-maintenance system. This system is part of our work on the european PROTEUS project [ITEA 01011, http://www.proteus-iteaproject.com/]. By using these modeling principles, industrials should be able to represent and simulate their remote maintenance systems in order to optimize them.

Scoop: A Complete Methodology for Cooperative Systems Modeling and Analysis

In this paper, we present our methodology proposal for cooperative remote systems modeling. Its aim is to develop models of existing or planned cooperative systems. These models are used to specify systems or to create dynamic working simulations. Comparative performances are deduced from the latter. The associated meta-model proposal is based, among other things, on the use of multi-agent systems, Petri nets and stochastics Petri nets. After having described the whole methodology concepts, we show a set of general results extracted from simulations.