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Vérification Efficace Et Nouvelles Techniques De Raisonnement Pour La Programmation Concurrente Par Contraintes
No full textConcurrent constraint programming (CCP) is a mature linguistic formalism from the family of process calculi and hence it treats processes much like the lambda-calculus treats computable functions. CCP is based on shared-memory communication where processes interact by adding and querying partial information represented as constraints (e.g., "x > 42") in a global store. This dissertation is focused on the development of novel reasoning techniques for program equivalence in CCP and their efficient verification.The first part of the thesis describes an algorithm for deciding strong bisimilarity for finite CCP processes. This is accomplished by first showing that the standard partition refinement approach does not work for CCP. Then it is shown how to adapt the standard approach for the case of CCP. Furthermore, it is proven that this procedure suffers from the state explosion, common in the verification of concurrent systems, due mostly to the presence of non-deterministic choices.The second part is devoted to the development of a weak semantics for CCP. As pointed out in the literature, one can use the procedure for strong bisimilarity to decide weak bisimilarity. The idea is to define a new transition relation based on the operational semantics. This method is known as saturation. The standard saturation is defined by omitting the silent transitions in the calculus. This works for CCS and other calculi, however in the case of CCP, because of its involved labeled transitions, it is shown that the standard technique is not complete. Then a new saturation is defined called weak semantics for CCP. It consists of the reflexive and transitive closure under any constraint in CCP instead of just closing with respect to the silent transitions. Most importantly, it is proven that the proposed weak semantics is sound and complete for CCP. As a consequence, the new saturation can be used for checking weak bisimilarity.In the third part the focus is shifted toward efficiency on the verification of weak bisimilarity. To achieve this, a representative sub-language of CCP is considered: the choice-free fragment (CCP\+). First, it is shown that the verification algorithms described above have an exponential-time complexity even for programs from CCP\+. Then by exploiting confluence, a distinctive feature from this fragment, two alternative polynomial-time decision procedures for CCP\+ weak bisimilarity are proposed. Each of these two procedures has an advantage over the other. One has a better time complexity, while the other can be easily adapted for the full language of CCP to produce significant state space reductions. The relevance of both procedures derives from the importance of CCP\+. This fragment, which has been the subject of much theoretical study, has strong ties to first-order logic and an elegant denotational semantics, and it can be used to model real-world situations. Most importantly, previously it was proven that weak bisimilarity in CCP\+ coincides with the standard observational equivalence for CCP\+. Hence from the results presented in this part, two efficient algorithms for checking program equivalence in CCP\+ are obtained.The last part addresses the congruence issue for the full language of CCP. It is shown that weak saturated barbed bisimilarity is not a congruence for CCP, as is the case for weak bisimilarity in CCS. This problem is tackled by introducing a new notion that characterizes the weakest equivalence included in the congruence induced by weak bisimilarity for CCP. We call this new notion weak full bisimilarity. More importantly, it is proven that weak full bisimilarity is a congruence for the full language of CCP. It is also shown that weak full bisimilarity coincides with the standard notion of observational equivalence in CCP\+. To the best of our knowledge, this is the first notion of weak bisimilarity that is a congruence for the full language of CCP.This dissertation contributes to the study of program equivalence in CCP. It provides an exponential-time decision procedure for strong bisimilarity in finite CCP as well as its adaptation to checking weak bisimilarity. Furthermore, this dissertation proposes two alternative polynomial-time algorithms for the verification of observational equivalence in the absence of nondeterministic choice. It concludes by proving that the existing notions of bisimilarity are not adequate for CCP with choice. Finally, it defines a novel reasoning technique which is proven to be the right notion of equivalence for the full language of CCP.La Programmation Concurrente par Contraintes (CCP) est un formalisme linguistique mature de la familledes algèbres de processus, il traite les processus de la même façon que le lambda-calcul traite lesfonctions calculables. CCP est basé sur la communication à mémoire partagée où les processus interagissenten ajoutant et en interrogeant des informations partielles représentées comme des contraintes (par exemple, "x > 42") dansune mémoire globale. Cette thèse se concentre sur le développement de nouvelles techniques de raisonnement pourl’équivalence des processus dans CCP et leur vérification efficace.La première partie de cette thèse décrit un algorithme pour calculer la bisimilarité forte pour des processusfinis du CCP. Ceci est accompli en montrant d'abord que l'approche de raffinement des partitions standard ne fonctionnepas pour CCP. Ensuite, il est montré comment adapter l'approche standard pour le cas de CCP. En outre,il est prouvé que cette procédure souffre de l'explosion combinatoire, commune à la vérification de systèmesconcurrents, principalement en raison de la présence de choix non-déterministe.La deuxième partie est consacrée à l'élaboration d'une sémantique faible pour CCP. Comme il estsouligné dans la littérature, on peut utiliser la procédure de bisimilarité forte pour décider la faible.L'idée est de définir une nouvelle relation de transition basée sur la sémantique opérationnelle, cette méthodeest connue comme la saturation. La saturation standard est définie par l'omission des transitions silencieuses dans le calcul.Cela fonctionne pour le CCS et d'autres calculs, mais dans le cas de la CCP, en raison de ses transitions plus complexes, ilest démontré que la technique standard n'est pas complète pour CCP. Ensuite, une nouvelle saturation est définie,nous l'appelons sémantique faible pour CCP. Elle consiste à la fermeture réflexive et transitive dans CCP au lieu desimplement la clôture sur les transitions silencieuses. Surtout, il est prouvé que la sémantique faible proposéeest correcte pour CCP. En conséquence, la nouvelle saturation peut être utilisée pour le calcul de la bisimilarité faible.La troisième partie est dédiée à l'efficacité de la vérification de la bisimilarité faible.Pour ce faire, un sous-langage représentant du CCP est considérée: le fragment sans choix non-déterministe (CCP\+).Tout d'abord, il est montré que les algorithmes de vérification précédents ont une complexité exponentielle même pourles processus de CCP\+. Ensuite, en exploitant la confluence, une caractéristique distinctive de ce fragment,deux algorithmes en temps polynomiales alternatifs pour la bisimilarité faible CCP\+ sont proposés.Chacune de ces deux procédures a un avantage sur l'autre. La première présente une meilleure complexitéen temps, alors que la seconde peut être facilement adaptéepour produire des importants améliorations dans l’algorithme pour tout le langage de CCP.La dernière partie aborde la question de la congruence dans tout CCP. Il est montré que la bisimilarité faiblen'est pas une congruence pour CCP, comme c'est le cas pour CCS. Ce problème est abordé par l'introduction d'unenouvelle notion qui caractérise l'équivalence la plus faible incluse dans la congruence induite par la bisimilaritéfaible pour CCP. Nous appelons cette nouvelle notion bisimilarité faible pleine. Plus important encore, il estprouvé que la bisimilarité faible pleine est une congruence pour CCP avec de choix non-déterministe.Il est également montré que la bisimilarité faible pleine coïncide avec la notion classique de l'équivalence observationnelle de CCP\+
Cytoplasmic mRNA surveillance pathways
No full textInternational audienceDuring mRNA synthesis and maturation, the introduction of errors can strongly influence the expression of certain genes and/or the activity of the proteins for which they encode. To minimise these defects, eukaryotic cells have evolved several cytoplasmic and translation-dependent quality control pathways aimed at detecting and degrading mRNAs that would lead to the production of aberrant proteins. The nonsense-mediated mRNA decay pathway (NMD) clears cells from mRNAs harbouring premature in-frame stop codons. Two other pathways (NSD for nonstop decay and NGD for No-Go decay) degrade mRNAs on which ribosomes have stalled during elongation. In this chapter, we describe the current knowledge on the biological roles and molecular mechanisms of these surveillance pathways, which were mainly unravelled using baker’s yeast as model system
Exploring diffusion across permeable barriers at high gradients. I. Narrow pulse approximation
No full textInternational audienc
Measurement of differential cross sections for the production of a pair of isolated photons in pp collisions at sqrt(s) = 7 TeV
No full textReplaced with published version. Added journal reference and DOI, see paper for full list of authorsInternational audienceA measurement of differential cross sections for the production of a pair of isolated photons in proton-proton collisions at sqrt(s) = 7 TeV is presented. The data sample corresponds to an integrated luminosity of 5.0 inverse femtobarns collected with the CMS detector. A data-driven isolation template method is used to extract the prompt diphoton yield. The measured cross section for two isolated photons, with transverse energy above 40 and 25 GeV respectively, in the pseudorapidity range abs(eta) 0.45, is 17.2 +/- 0.2 (stat.) +/- 1.9 (syst.) +/- 0.4 (lum.) pb. Differential cross sections are measured as a function of the diphoton invariant mass, the diphoton transverse momentum, the azimuthal angle difference between the two photons, and the cosine of the polar angle in the Collins-Soper reference frame of the diphoton system. The results are compared to theoretical predictions at leading, next-to-leading, and next-to-next-to-leading order in quantum chromodynamics
Ingénierie des modèles dans une EPS modulaire
No full textFor the purpose of PSA (Probabilistic Safety Analysis) for complex industrial systems, often PSA models in the form of fault and event trees are developed to model the risk of unwanted situations (hazards). While the recent decades, PSA models have gained high acceptance and have been developed massively. This led to an increase in model sizes and complexity. Today, PSA models are often difficult to understand and maintain.This manuscript presents the concept of a modular PSA. A modular PSA tries to cope with the increased complexity by the techniques of modularization and instantiation. Modularization targets to treat a model by smaller pieces (the ``modules'') to regain control over models. Instantiation aims to configure a generic model to different contexts. Both try to reduce model complexity.A modular PSA enables to apply new functionality for model management. Current PSA model management is often characterized to be limited or inefficient. This manuscript shows new methods to manage the evolution (versions) and deviations (variants) of PSA models in a modular PSA.The concepts of version and variant management are presented in this thesis. In this context, a method to compare and fusion PSA models isprecised. Model comparison provides important feedback to model engineers and model fusion targets to combine the work from different model engineers (concurrent model engineering).Apart from model management, methods to understand the content of PSA models are presented. The methods focus on highlighting the dependencies between modules rather than their contents. Dependencies are automatically derived from a model structure. They express relations between model objects (for example a fault tree may have dependencies to basic events). The visualization of those dependencies (for example in form of a model cartography) can constitute a crucial aid to model engineers for understanding complex interrelations in PSA models.Within the scope of this thesis, a software named ``Andromeda'' has been developed at EDF R&D to test and evaluate the concepts around a modular PSA. Andromeda is based on a modular and extensible architecture that can be customized to specific needs of customers. Apart from research interest, it has recently gained industrial interest. Andromeda has potential to augment existing PSA tools by specific functionality they lack and to promote common modeling standards and techniques within the international PSA community.Dans le cadre de l’EPS (Étude Probabiliste de Sûreté) pour des systèmes industriels complexes, souvent les modèles EPS sont développés sous la forme d’arbres de défaillances et d‘événements pour modéliser les risques des situations non attendues (hasard). Au cours des dernières décennies, les modèles EPS ont été de plus en plus acceptés et développés. Cela a conduit à un accroissement de la taille des modèles et de leur complexité.Aujourd'hui, les modèles EPS sont souvent difficiles à comprendre et maintenir. Ce manuscrit présente le concept de l’EPS modulaire. Une EPS cherche à faire face à la complexité croissante par les techniques de modularisation et d’instanciation. La modularisation vise à traiter les modèles en petits morceaux (les “modules”) pour mieux comprendre ces modèles. L’instanciation a pour but de configurer un modèle générique à des contextes différents. Une EPS modulaire permet d'appliquer des nouvelles fonctionnalités pour gérer les modèles. La gestion actuelle des modèles EPS a souvent ses limites. Cette thèse montre de nouvelles méthodes pour gérer les évolutions (versions) et les variations (variantes) des modèles EPS dans une EPS modulaire. Les concepts de versions et de variantes sont présentées dans cette étude. Une méthode de comparaison et fusion des modèles EPS est précisée. La comparaison des modèles apporte des informations intéressantes aux ingénieurs de modèles et la fusion des modèles permet de combiner leurs différents travaux.Des méthodes pour comprendre le contenu des modèles EPS sont également introduites. Ces dernières mettent l’accent sur les dépendances entre les modules plutôt que sur leur contenu. Les dépendances viennent automatiquement d’une structure de modèle. Elles expriment les relations entre les objets de modèle (par exemple un arbre de défaillances peut créer des dépendances vers des événements de base). Les possibilités de visualiser ces dépendances (par exemple sous la forme d’une cartographie de modèles) peuvent être une aide précieuse pour les ingénieurs de modèle afin d’analyser les corrélations complexes dans les modèles EPS.Dans le cadre de cette thèse, un logiciel nommé “Andromeda” a été développé au sein du département Recherche et Développement d’EDF pour tester et évaluer les concepts autour d’une EPS modulaire. Andromeda se base sur une architecture modulaire et extensible qui peut être adaptée aux besoins spécifiques des utilisateurs. En plus de l’intérêt de la recherche, Andromeda a gagné récemment celui de l’industrie. Il a le potentiel de compléter les outils EPS actuels par des fonctionnalités spécifiques et de faire appliquer à la communauté internationale EPS des techniques et normes de modélisation communes
BASTA : a 95GHz FM-‐CW Cloud radar
No full textInternational audienceGround-based continuous observation of non-precipitating clouds and fo
Gain dynamics in a soft-X-ray laser amplifier perturbed by a strong injected X-ray field
No full textInternational audienceSeeding soft-X-ray plasma amplifiers with high harmonics has been demonstrated to generate high-brightness soft-X-ray laser pulses with full spatial and temporal coherence. The interaction between the injected coherent field and the swept-gain medium has been modelled. However, no experiment has been conducted to probe the gain dynamics when perturbed by a strong external seed field. Here, we report the first X-ray pump–X-ray probe measurement of the nonlinear response of a plasma amplifier perturbed by a strong soft-X-ray ultra-short pulse. We injected a sequence of two time-delayed high-harmonic pulses (λ = 18.9 nm) into a collisionally excited nickel-like molybdenum plasma to measure with femtosecond resolution the gain depletion induced by the saturated amplification of the high-harmonic pump and its subsequent recovery. The measured fast gain recovery in 1.5–1.75 ps confirms the possibility to generate ultra-intense, fully phase-coherent soft-X-ray lasers by chirped pulse amplification in plasma amplifiers
Climatology of free-tropospheric humidity: extension into the SEVIRI era, evaluation and exemplary analysis
No full textA new free tropospheric humidity (FTH) data record is presented. It is based on observations of Meteosat-2-5 and Meteosat-7 Meteosat Visible and Infrared Imager (MVIRI) and Meteosat-8 and -9 Spinning Enhanced Visible and Infrared Imager (SEVIRI) at the water absorption band at 6.3 μm. With the extension to SEVIRI observations the data record now covers the period 1983-2009 with a spatial and temporal resolution of 0.625° and 3 h, respectively. The data record is referenced under digital object identifier (doi): 10.5676/EUM_SAF_CM/FTH_METEOSAT/V001 and is freely available from http://www.cmsaf.eu/wui . The relation between the observed brightness temperature (BT) and FTH is well established: the observed BT is proportional to the logarithm of the mean relative humidity (RH). Under the given assumptions, constant lapse rate and random strong line theory, it means that the observed BT is mainly a function of RH alone and not of temperature and specific humidity separately. Here, existing retrievals have been refined mainly through the consideration of relative humidity Jacobians in the training process of the statistical retrieval. The temporal coverage has been extended into the SEVIRI era, the homogenisation of the BT record has been improved and the full archive has been reprocessed using updated regression coefficients. The FTH product is compared against FTH computed on the basis of the Analysed RadioSoundings Archive (ARSA) observations. An average relative bias and root mean square difference (RMSD) of −3.2 and 16.8%, respectively, are observed. The RMSD confirms the expectation from an analysis of the total uncertainty of the FTH product. The decadal stability is 0.5 ± 0.45% per decade. As exemplary applications the inter-annual standard deviation, differences on decadal scales and the linear trend in the FTH data record and the frequency of occurrence of FTH <10% (FTHp10) are analysed per season. Maxima in inter-annual standard deviations as well as maxima in absolute differences occur in gradient areas between dry and wet regions and areas with minima in FTH and maxima in FTHp10. An analysis of the linear trends and associated uncertainty estimates has been attempted to identify possible problems with the data record. Positive trends in FTHp10 coincide with gradient areas and regions of minimum FTH, maximum FTHp10 as well as with negative differences between decadal FTHp10 averages of the 1990s and 2000s. However, they are accompanied by maximum standard deviation and are therefore hardly significant which is also valid for FTH trend estimates. These activities plus inter-comparisons to other humidity data records are part of the Global Energy and Water Exchanges Project (GEWEX) water vapor assessment (G-VAP) and will be extended to other FTH data records in the near future
FanTaaStic: Sustainable management of Future Internet testbed federations
No full textInternational audienceThe global trend of Future Internet related experimentally driven research has gained a strong momentum. In this context sustainability and the best use of developed infrastructures are highly critical. While many facilities have reached a level of maturity that allows them to be opened up to a wider use, mainly the academic sectors have been targeted. The Fanning out Testbeds-as-a-Service for the EIT ICT1 (FanTaaStic) project explores best practices, has performed a gap analysis, investigates applicable business models and works out a concept for the operation of a self-sustainable commercial testbed service offering. For defining the operational model, an analysis of available tools and frameworks from past and current Future Internet testbed projects is being carried out, based on a standard framework that defines the required processes and applications for the carrier grade operation of telecommunication infrastructures and provisioning of services. The business model is defined as a gradually growing service offering, based on categories of a framework for IT Service Management in federated e-infrastructures. The applicability of both, the developed business and operational model for such a sustainable federation will initially be implemented and evaluated in 2014
Les comportements déviants des clients dans la réclamation : une typologie des stratégies organisationnelles
No full textSoumission en coursInternational audienceLa littérature souligne qu’une bonne gestion des réclamations est cruciale dans uneoptique de satisfaction et de fidélisation des clients. Cependant, les organisationsfont également face à de nombreux comportements «déviants» de leurs clients au cours de la réclamation: fraude, agressivité, injustice, etc. Ceux-ci ont des conséquences négatives, tant sur le personnel que sur le plan financier qu’il convient d’anticiper. Or, la littérature ne donne que peu de pistes sur les stratégies que lesorganisations peuvent déployer pour gérer ces déviances au cours de la réclamation.Le but de cet article est d’approfondir la compréhension théorique des stratégies que les organisations peuvent mettre en place face aux comportements déviants dans le contexte de la réclamation. Basé sur une recherche qualitative menée auprès decinq cas d’organisations de secteurs différents, l’apport de l’article est alors de mettre en lumière qu’il existe quatre grands types de stratégies face aux comportements déviants dans la réclamation : la stratégie tolérante, la stratégie d’éducation, la stratégie de séparation et la stratégie d’expertise. L’article montre que chacune de ces stratégies est plus ou moins adaptée en fonction de la criticité du comportementdéviant et de la nature des acteurs qui sont impactés par la déviance