Automated Polyhedral Abstraction Proving

We propose an automated procedure to prove polyhedral abstractions for Petri nets. Polyhedral abstraction is a new type of state-space equivalence based on the use of linear integer constraints. Our approach relies on an encoding into a set of SMT formulas whose satisfaction implies that the equivalence holds. The difficulty, in this context, arises from the fact that we need to handle infinite-state systems. For completeness, we exploit a connection with a class of Petri nets that have Presburger-definable reachability sets. We have implemented our procedure, and we illustrate its use on several examples

Porosities accessible to HTO and iodide on water-saturated compacted clay materials and relation with the forms of water: A low field proton NMR study

International audienceThe aim of the present work was to quantify accessible porosities for iodide and for a water tracer (HTO) on water-saturated compacted clay samples (illite, montmorillonite and MX-80 bentonite) and to relate these macroscopic values to the forms of water in these porosities (surface/bulk water, external/internal water). Low field proton NMR was used to characterize and quantify the forms of water. This enabled the three different populations (structural OH, external surface and internal surface water) to be differentiated on hydrated clays by considering the difference in proton mobility. An accurate description of the water forms within the different populations did not appear possible when water molecules of these populations were in contact because of the occurrence of rapid exchange reactions. For this reason, it was not possible to use the low resolution NMR method to quantify external surface and bulk water in fully water-saturated compacted clay media at room temperature. This latter information could however be estimated when analyzing the samples at -25°C. At this temperature, a distinction based on the difference in mobility could be made since surface water remained in a semi-liquid state whereas bulk water froze. In parallel, accessible porosities for anions and HTO were determined by an isotopic dilution method using capillaries to confine the materials. HTO was shown to probe the whole pore volume (i.e. the space made of surface and bulk water). When the surface water volume was mainly composed of interlayer water (case of montmorillonite and bentonite), iodide was shown to be located in the pore space made of bulk water. When the interlayer water was not present (case of illite), the results showed that iodide could access a small fraction of the surface water volume localized at the external surface of the clay particles

From FMTV to WATERS: Lessons Learned from the First Verification Challenge at ECRTS

We present here the main features and lessons learned from the first edition of what has now become the ECRTS industrial challenge, together with the final description of the challenge and a comparative overview of the proposed solutions. This verification challenge, proposed by Thales, was first discussed in 2014 as part of a dedicated workshop (FMTV, a satellite event of the FM 2014 conference), and solutions were discussed for the first time at the WATERS 2015 workshop. The use case for the verification challenge is an aerial video tracking system. A specificity of this system lies in the fact that periods are constant but known with a limited precision only. The first part of the challenge focuses on the video frame processing system. It consists in computing maximum values of the end-to-end latency of the frames sent by the camera to the display, for two different buffer sizes, and then the minimum duration between two consecutive frame losses. The second challenge is about computing end-to-end latencies on the tracking and camera control for two different values of jitter. Solutions based on five different tools - Fiacre/Tina, CPAL (simulation and analysis), IMITATOR, UPPAAL and MAST - were submitted for discussion at WATERS 2015. While none of these solutions provided a full answer to the challenge, a combination of several of them did allow to draw some conclusions

From FMTV to WATERS: Lessons Learned from the First Verification Challenge at ECRTS

We present here the main features and lessons learned from the first edition of what has now become the ECRTS industrial challenge, together with the final description of the challenge and a comparative overview of the proposed solutions. This verification challenge, proposed by Thales, was first discussed in 2014 as part of a dedicated workshop (FMTV, a satellite event of the FM 2014 conference), and solutions were discussed for the first time at the WATERS 2015 workshop. The use case for the verification challenge is an aerial video tracking system. A specificity of this system lies in the fact that periods are constant but known with a limited precision only. The first part of the challenge focuses on the video frame processing system. It consists in computing maximum values of the end-to-end latency of the frames sent by the camera to the display, for two different buffer sizes, and then the minimum duration between two consecutive frame losses. The second challenge is about computing end-to-end latencies on the tracking and camera control for two different values of jitter. Solutions based on five different tools - Fiacre/Tina, CPAL (simulation and analysis), IMITATOR, UPPAAL and MAST - were submitted for discussion at WATERS 2015. While none of these solutions provided a full answer to the challenge, a combination of several of them did allow to draw some conclusions

Un règlement européen relatif à la gestion des espèces exotiques envahissantes : grands axes d’actions et points de débats

Face aux enjeux environnementaux et économiques représentés par les invasions biologiques, les instances européennes ont proposé un règlement aux États membres afin de coordonner leurs efforts pour développer la prévention et réduire les impacts de ces espèces à l'échelle de l'Union. Focus sur les principales orientations d'action et les points de débats

MLF : Une extension de ML avec polymorphisme de second ordre et instanciation implicite

Directeur de thèse : Didier Rémy (INRIA Rocquencourt) Rapporteur : Benjamin Pierce (Université de Pennsylvanie, USA) Rapporteur : Jacques Garrigue (Université de Kyoto, Japon) Président : Roberto Di Cosmo (Université Paris 7) Examinateur : Claude Kirchner (INRIA Lorraine) Examinateur : Dale Miller (Ecole Polytechnique)We propose a type system MLF that generalizes ML with first-classpolymorphism as in System F. Expressions may contain second-order typeannotations. Every typable expression admits a principal type, whichhowever depends on type annotations. Principal types capture all othertypes that can be obtained by implicit type instantiationand they can be inferred.All expressions of ML are well-typed without any annotations.All expressions of System F can be mechanically encoded into MLFby dropping all type abstractions and type applications,and injecting type annotations of lambda-abstractions into MLF types.Moreover, only parameters of lambda-abstractions that are usedpolymorphically need to remain annotated.Nous nous intéressons à une extension de ML avec polymorphismede première classe, à la manière du Système F.Cette extension, nommée MLF, utilise les annotations de typesd'ordre supérieur données explicitement dans le programme pour inférerde manière principale le type le plus général. Toute expression admetainsi un type principal, qui dépend des annotations présentesinitialement dans le programme.Toute expression de ML est typable dans MLF sans annotationsupplémentaire. Les expressions du Système F sont encodées demanière systématique dans MLF en supprimant les abstractionset les applications de types, et en traduisant les annotationsde types dans le langage de types de MLF.De plus, les paramètres de lambda-abstractions qui ne sont pasutilisés de manière polymorphe n'ont pas besoin d'être annotés

Applications de la résonance magnétique nucléaire (RMN) en milieu poreux Lissage des courbes de relaxation RMN du domaine du temps par une méthode discrète et continue

Dans un champ magnétique hétérogène, le signal RMN de précession libre (FID) suit une évolution gaussienne. Le traitement du signal par une méthode discrète peut donner des composantes qui ne correspondent pas à un état physique réel. Par contre l'utilisation d'une méthode de déconvolution continue nous a donné des résultats quantitatifs tout à fait satisfaisants permettant de déterminer les distributions de temps de relaxation correspondant à des états intermédiaires entre les phases solides et liquides. La RMN du domaine du temps peut ainsi être considérée comme une méthode analytique complémentaire des techniques habituellement utilisées pour l'étude de composés complexes hétérogènes ATD, ACD, isothermes de sorption, etc