Testing Membership for Timed Automata

Given a timed automata which admits thick components and a timed word $x$, we present a tester which decides if $x$ is in the language of the automaton or if $x$ is $\epsilon$-far from the language, using finitely many samples taken from the weighted time distribution $\mu$ associated with an input $x$. We introduce a distance between timed words, the {\em timed edit distance}, which generalizes the classical edit distance. A timed word $x$ is $\epsilon$-far from a timed language if its relative distance to the language is greater than $\epsilon$.Comment: 26 page

Distribution, Approximation and Probabilistic Model Checking

AbstractAPMC is a model checker dedicated to the quantitative verification of fully probabilistic systems against LTL formulas. Using a Monte-Carlo method in order to efficiently approximate the verification of probabilistic specifications, it could be used naturally in a distributed framework. We present here the tool and its distribution scheme, together with extensive performance evaluation, showing the scalability of the method, even on clusters containing 500+ heterogeneous workstations

Étude expérimentale du mélange solide-liquide : caractérisation des suspensions concentrées en milieu visqueux

Ce mémoire présente une étude expérimentale du mélange solide-liquide en milieu visqueux et pour des concentrations élevées en solides, un système de mélange encore peu connu et responsable de fortes pertes industrielles. Le mélangeur est une cuve mécaniquement agitée par une turbine à pales inclinées, un agitateur fréquemment utilisé par les industries chimiques. Dans un objectif de compréhension hydrodynamique et phénoménologique, trois paramètres ont été caractérisés: la vitesse minimale de suspension complète (Njs), la vitesse d’homogénéisation (NH) et le temps d’homogénéisation (tH). La technique de pression de jauge (PGT) et la tomographie par résistance électrique (ERT) ont été implémentées pour la détermination respective de Njs et NH et tH. L’étude est complétée par la mesure du couple et de la hauteur de suspension, ainsi que par l’utilisation d’un modèle numérique développé dans le groupe. Tout d’abord, la méthode de pression de jauge a été adaptée avec succès aux régimes laminaire et transitoire, et montre une répétabilité et une stabilité adéquates. Un plan d’expérience optimal a permis d’évaluer l’effet de cinq facteurs majeurs sur l’hydrodynamique du mélange: le diamètre des particules (dp), la fraction massique de solides (Xw), la viscosité du fluide (μ), le diamètre de l’agitateur (D) et le dégagement au fond (C). En régime transitoire, comme en régime turbulent, Njs et NH diminuent pour de larges agitateurs. Les effets de dp et de μ montrent un comportement opposé à celui observé en turbulent puisque Njs diminue lorsque dp et μ augmentent. De plus, Xw présente un impact complexe, dépendant en partie de la taille des particules. Ces observations ont été associées à un phénomène d’érosion de lit dont le mécanisme diffère largement de la suspension en régime turbulent. Ces particularités expliquent les déviations observées avec les valeurs prédites par la corrélation de Zwietering (Zwietering, 1958). Tout comme pour D/T, les effets de Xw, dp et C/T sur NH sont équivalents à ceux rapportés en régime turbulent, puisque NH augmente lorsque Xw et dp augmentent, et lorsque C/T diminue. L’étude de tH démontre que l’obtention d’une suspension homogène à partir de particules sédimentées est majoritairement contrôlée par leur mise en suspension. La coopération entre caractérisation expérimentale et étude numérique a permis d’une part d’attester de la validité phénoménologique du modèle, et d’autre part d’apporter de nouveau éléments à la compréhension hydrodynamique du système étudié. Mots-clefs: mélange solide-liquide – fluide visqueux – suspensions concentrées – cuve mécaniquement agitée – vitesse minimale de suspension ---------- To address a considerable lack of knowledge in solid-liquid mixing, the suspension of large concentrations of spherical particles in a viscous fluid is investigated through the experimental characterization of fundamental mixing parameters: the just-suspension speed (Njs), the homogenization speed (NH) and the homogenization time (tH). Known for its great efficiency for suspending particles in turbulent regime, and commonly used in the chemical industry, the pitched blade turbine is investigated. Njs is characterized by the pressure gauge technique (PGT), NH and tH are measured using a robust and simple technique of electrical resistance tomography (ERT). The description of the system is further characterized by means of power consumption and cloud height measurements, and by comparing the experimental data to numerical results. First, the PGT method was successfully adapted to laminar and transitional regimes of operation, with good reproducibility and stability. To explore the effect of particle diameter (dp), solid mass concentration (Xw), viscosity (μ), impeller diameter (D) and bottom-off clearance (C), an optimal design of experiment was carried out, from which the effects of every factor was determined. In early transitional regime with non-dilute concentration of solid particles, an increase in D causes Njs and NH to considerably decrease, as also reported in turbulent regime. Unlike the prediction of the well-known Zwietering correlation (Zwietering, 1958), it is found that increasing dp or μ leads to a decrease of Njs. In addition, the effect of solid concentration is more complex than what is predicted by the Zwietering correlation, showing a dependency on dp. The large discrepancies observed between our experimental values and Zwietering correlation values of Njs are related to the differences in hydrodynamics and suspension mechanisms regarding the operating regime. The effects of dp and μ for solid suspensions in a viscous liquid appear to correspond to the erosion of a bed of particles. The impact of Xw, dp and C/T on NH are similar to those reported on turbulent regime. The study on the homogenization time tH shows that the erosion of the particle bed is the dominating phenomenon to consider in order to achieve a fully suspended state and an uniform distribution of the particles. Finally, the numerical model developed in our group is validated by comparison with experimental data, and is used to fully understand the mixing system investigated. Keywords: solid-liquid mixing - viscous fluid - high solid loading – stirred tank – just suspended spee

Logic of Negation-Complete Interactive Proofs (Formal Theory of Epistemic Deciders)

We produce a decidable classical normal modal logic of internalised negation-complete and thus disjunctive non-monotonic interactive proofs (LDiiP) from an existing logical counterpart of non-monotonic or instant interactive proofs (LiiP). LDiiP internalises agent-centric proof theories that are negation-complete (maximal) and consistent (and hence strictly weaker than, for example, Peano Arithmetic) and enjoy the disjunction property (like Intuitionistic Logic). In other words, internalised proof theories are ultrafilters and all internalised proof goals are definite in the sense of being either provable or disprovable to an agent by means of disjunctive internalised proofs (thus also called epistemic deciders). Still, LDiiP itself is classical (monotonic, non-constructive), negation-incomplete, and does not have the disjunction property. The price to pay for the negation completeness of our interactive proofs is their non-monotonicity and non-communality (for singleton agent communities only). As a normal modal logic, LDiiP enjoys a standard Kripke-semantics, which we justify by invoking the Axiom of Choice on LiiP's and then construct in terms of a concrete oracle-computable function. LDiiP's agent-centric internalised notion of proof can also be viewed as a negation-complete disjunctive explicit refinement of standard KD45-belief, and yields a disjunctive but negation-incomplete explicit refinement of S4-provability.Comment: Expanded Introduction. Added Footnote 4. Corrected Corollary 3 and 4. Continuation of arXiv:1208.184

Centre de recherches interdisciplinaires sur l’Allemagne

Jean-Louis Georget, maître de conférences à l’Université Paris-XIIIDominique Lassaigne, ingénieur d’études au CNRS L’Allemagne à l’épreuve de la Volkskunde La phase d’institutionnalisation de la Volkskunde se développe dans les années 1920 : cette dernière relève des circonstances exceptionnelles de la sortie du premier conflit mondial et du caractère conservateur au sens conceptuel de la Volkskunde. En croisant l’analyse de l’anatomie d’une génération et les œuvres de Hans Naumann, Julius Sc..

Centre de recherches interdisciplinaires sur l’Allemagne

Dominique Lassaigne, ingénieur d’études au CNRS et Jean-Louis Georget, maître de conférences à l’Université de Paris-XIII L’Allemagne à l’épreuve de la Volkskunde La Volkskunde, ou l’ethnologie allemande appliquée à l’Allemagne, est une discipline fondée au XIXe siècle par l’historien de la culture Wilhelm Heinrich Riehl (1823-1897). La discipline, qui connaît une plénitude universitaire à partir des années 20, va se trouver piégée par sa récupération par les nazis sous le IIIe Reich, comme l..

Probabilistic Model Checking of the CSMA/CD Protocol Using PRISM and APMC

AbstractCarrier Sense Multiple Access/Collision Detection (CSMA/CD) is the protocol for carrier transmission access in Ethernet networks (international standard IEEE 802.3). On Ethernet, any Network Interface Card (NIC) can try to send a packet in a channel at any time. If another NIC tries to send a packet at the same time, a collision is said to occur and the packets are discarded. The CSMA/CD protocol was designed to avoid this problem, more precisely to allow a NIC to send its packet without collision. This is done by way of a randomized exponential backoff process. In this paper, we analyse the correctness of the CSMA/CD protocol, using techniques from probabilistic model checking and approximate probabilistic model checking. The tools that we use are PRISM and APMC. Moreover, we provide a quantitative analysis of some CSMA/CD properties

Development of an unresolved CFD–DEM model for the flow of viscous suspensions and its application to solid–liquid mixing

Although viscous solid–liquid mixing plays a key role in the industry, the vast majority of the literature on the mixing of suspensions is centered around the turbulent regime of operation. However, the laminar and transitional regimes face considerable challenges. In particular, it is important to know the minimum impeller speed () that guarantees the suspension of all particles. In addition, local information on the flow patterns is necessary to evaluate the quality of mixing and identify the presence of dead zones. Multiphase computational fluid dynamics (CFD) is a powerful tool that can be used to gain insight into local and macroscopic properties of mixing processes. Among the variety of numerical models available in the literature, which are reviewed in this work, unresolved CFD–DEM, which combines CFD for the fluid phase with the discrete element method (DEM) for the solid particles, is an interesting approach due to its accurate prediction of the granular dynamics and its capability to simulate large amounts of particles. In this work, the unresolved CFD–DEM method is extended to viscous solid–liquid flows. Different solid–liquid momentum coupling strategies, along with their stability criteria, are investigated and their accuracies are compared. Furthermore, it is shown that an additional sub-grid viscosity model is necessary to ensure the correct rheology of the suspensions. The proposed model is used to study solid–liquid mixing in a stirred tank equipped with a pitched blade turbine. It is validated qualitatively by comparing the particle distribution against experimental observations, and quantitatively by compairing the fraction of suspended solids with results obtained via the pressure gauge technique

A semi-implicit immersed boundary method and its application to viscous mixing

Computational fluid dynamics (CFD) simulations in the context of single-phase mixing remain challenging notably due the presence of a complex rotating geometry within the domain. In this work, we develop a parallel semi-implicit immersed boundary method based on Open∇FOAM, which is applicable to unstructured meshes. This method is first verified on academic test cases before it is applied to single phase mixing. It is then applied to baffled and unbaffled stirred tanks equipped with a pitched blade impeller. The results obtained are compared to experimental data and those predicted with the single rotating frame and sliding mesh techniques. The proposed method is found to be of comparable accuracy in predicting the flow patterns and the torque values while being straightforwardly applicable to complex systems with multiples impellers for which the swept volumes overlap