Volume 8, Special Issue CARI'06, 2008

1. Observer design for a fish population model

El Houssine El Mazoudi ; mostafa Mrabti ; Noureddine Elalami.
Our aim is to apply some tools of control to fishing population systems. In this paper we construct a non linear observer for the continuous stage structured model of an exploited fish population, using the fishing effort as a control term, the age classes as a states and the quantity of captured fish as a measured output. Under some biological satisfied assumptions we formulate the observer corresponding to this system and show its exponential convergence. With the Lie derivative transformation, we show that the model can be transformed to a canonical observable form; then we give the explicit gain of the estimation.

2. Projections et cohérence de vues dans les grammaires algébriques

Eric Badouel ; Maurice Tchoupé Tchendji.
A complex structured document is intentionnally represented as a tree decorated with attributes. The set of legal structures is given by an abstract context-free grammar. We forget about the attributes; they are related with semantical issues that can be treated independently of the purely structural aspects that we address in this article. That intentional representation may be asynchronously manipulated by a set of independent tools each of which operates on a distinct partial view of the whole structure. In order to synchronize these various partial views, we are faced to the problem of their coherence: can we decide whether there exists some global structure corresponding to a given set of partial views and in the affirmative, can we produce such a global structure ? We solve this problem in the case where a view is given by a subset of grammatical symbols, those associated with the so-called visible syntactical categories. The proposed algorithm, that strongly relies on the mechanism of lazy evaluation, produces an answer to this problem even if partial views may correspond to an infinite set of related global structures.

3. Interoperability test generation: formal definitions and algorithm

Alexandra Desmoulin ; César Viho.
In the context of network protocols, interoperability testing is used to verify that two (or more) implementations communicate correctly while providing the services described in their respective specifications. This study is aimed at providing a method for interoperability test generation based on formal definitions. Contrary to previous works, this study takes into account quiescence of implementations that may occur during interoperability testing. This is done through the notion of interoperability criteria that give formal definitions of the different existing pragmatic interoperability notions. It is first proved that quiescence management improves non-interoperability detection. Two of these interoperability criteria are proved equivalent leading to a new method for interoperability test generation. This method avoids the well-known state explosion problem that may occur when using existing classical approaches.

4. Méthodes MCMC en interaction pour l'évaluation de ressources naturelles

Fabien Campillo ; Philippe Cantet ; Rivo Rakotozafy ; Vivien Rossi.
Markov chain Monte Carlo (MCMC) methods together with hidden Markov models are extensively used in the Bayesian inference for many scientific fields like environment and ecology. Through simulated examples we show that the speed of convergence of these methods can be very low. In order to improve the convergence properties, we propose a method to make parallel chains interact. We apply this method to a biomass evolution model for fisheries.

5. Ondes locales dans les milieux hétérogènes - Aspects numériques

Philippe Destuynder ; Olivier Wilk.
Lorsqu'un milieu présente une vitesse d'onde inférieure à celles de ceux qui l'entourent, un mécanisme de localisation d'énergie vibratoire peut apparaître. Cela provient du fait qu'une partie plus importante de l'énergie est réfléchie du côté du milieu le plus souple. Or la transition conduit à des contraintes d'interface très fortes qui sont susceptibles de créer un endommagement local. Notre ambition est de proposer une stratégie d'évaluation de l'énergie de ces surcontraintes sous forme d'un taux de restitution dynamique de l'énergie totale du système qui ne nécessite pas un calcul très précis au voisinage de l'interface.