Development of advanced control strategies for Adaptive Optics systems

Atmospheric turbulence is a fast disturbance that requires high control frequency. At the same time, celestial objects are faint sources of light and thus WFSs often work in a low photon count regime. These two conditions require a trade-off between high closed-loop control frequency to improve the disturbance rejection performance, and large WFS exposure time to gather enough photons for the integrated signal to increase the Signal-to-Noise ratio (SNR), making the control a delicate yet fundamental aspect for AO systems. The AO plant and atmospheric turbulence were formalized as state-space linear time-invariant systems. The full AO system model is the ground upon which a model-based control can be designed. A Shack-Hartmann wavefront sensor was used to measure the horizontal atmospheric turbulence. The experimental measurements yielded to the Cn2 atmospheric structure parameter, which is key to describe the turbulence statistics, and the Zernike terms time-series. Experimental validation shows that the centroid extraction algorithm implemented on the Jetson GPU outperforms (i.e. is faster) than the CPU implementation on the same hardware. In fact, due to the construction of the Shack-Hartmann wavefront sensor, the intensity image captured from its camera is partitioned into several sub-images, each related to a point of the incoming wavefront. Such sub-images are independent each-other and can be computed concurrently. The AO model is exploited to automatically design an advanced linear-quadratic Gaussian controller with integral action. Experimental evidence shows that the system augmentation approach outperforms the simple integrator and the integrator filtered with the Kalman predictor, and that it requires less parameters to tune

Detecting component changes at run time with behavior models

Modern software systems are composed of several services which may be developed and maintained by third parties and thus they can change independently and without notice during the system’s runtime execution. In such systems, changes may possibly be a threat to system functional correctness, and thus to its reliability. Hence, it is important to detect them as soon as they happen to enable proper reaction. Change detection can be done by monitoring system execution and comparing the observed execution traces against models of the services composing the application. Unfortunately, formal specifications for services are not usually provided and developers have to infer them. In this paper we propose a methodology which exactly addresses these issues by using software behavior models to monitor component execution and detect changes. In particular, we describe a technique to infer behavior model specifications with a dynamic black box approach, keep them up-to-date with run time observations and detect behavior changes. Finally, we present a case study to validate the effectiveness of the approach in component change detection for a component that implements a complex, real communication protocol.European Commission (Programme IDEAS-ERC, Project 227977-SMScom

A direct solution of allocation problems

AbstractThis paper deals with tree-structured networks that interconnect n given points A1,..., An in the plane through up to (n – 2) auxiliary junction points S1,..., Sn − 2. The problem of locating these auxiliary vertices is tackled to minimize the total cost of the connection network. The formulation of the problem is not bound by the condition that specific link costs are equal for all branches, in order to comprise a broader range of applications, such as distribution networks. Starting from a well-known mechanical analogy, the authors arrive at some mathematical expressions and conditions of their applicability that allow calculation of the optimal coordinates of the unknown Si points directly without resorting to the usual iterative procedures. The method is illustrated for the case of n = 3 points and its extension to more general cases is presented. The formulas obtained also apply to the particular case of determining Steiner minimal trees, specific link cost being constant. An example of application to electric distribution networks is also given

Holistic recommender systems for software engineering

The knowledge possessed by developers is often not sufficient to overcome a programming problem. Short of talking to teammates, when available, developers often gather additional knowledge from development artifacts (e.g., project documentation), as well as online resources. The web has become an essential component in the modern developer’s daily life, providing a plethora of information from sources like forums, tutorials, Q&A websites, API documentation, and even video tutorials. Recommender Systems for Software Engineering (RSSE) provide developers with assistance to navigate the information space, automatically suggest useful items, and reduce the time required to locate the needed information. Current RSSEs consider development artifacts as containers of homogeneous information in form of pure text. However, text is a means to represent heterogeneous information provided by, for example, natural language, source code, interchange formats (e.g., XML, JSON), and stack traces. Interpreting the information from a pure textual point of view misses the intrinsic heterogeneity of the artifacts, thus leading to a reductionist approach. We propose the concept of Holistic Recommender Systems for Software Engineering (H-RSSE), i.e., RSSEs that go beyond the textual interpretation of the information contained in development artifacts. Our thesis is that modeling and aggregating information in a holistic fashion enables novel and advanced analyses of development artifacts. To validate our thesis we developed a framework to extract, model and analyze information contained in development artifacts in a reusable meta- information model. We show how RSSEs benefit from a meta-information model, since it enables customized and novel analyses built on top of our framework. The information can be thus reinterpreted from an holistic point of view, preserving its multi-dimensionality, and opening the path towards the concept of holistic recommender systems for software engineering

Pelvoux – Haute vallée de l’Eychauda-Chambran

Identifiant de l'opération archéologique : 8520 Date de l'opération : 2007 (PR) Dans la continuité des opérations archéologiques entreprises depuis 1998 sur les hauts massifs alpins de l’Argentiérois/Vallouise dans le Parc national des Écrins, une campagne de prospection-inventaire diachronique a été réalisée en juin 2007 dans la haute vallée de l’Eychauda-Chambran (1 700 m-2 980 m d’altitude), à l’extrémité nord de la commune de Pelvoux. Aucun site archéologique n’était répertorié sur ce se..

From amines to (form)amides: a simple and successful mechanochemical approach

Two easily accessible routes for preparing an array of formylated and acetylated amines under mechanochemical conditions are presented. The two methodologies exhibit complementary features as they enable the derivatization of aliphatic and aromatic amines

Du climat à l'homme : Dynamique holocène de l'environnement dans le jura et les alpes Actes du colloque GDR JURALP organisé à Aix-en-Provence les 15 et 16 novembre 2007

L'éditeur autorise la diffusion de ce numéro dans une archive ouverte.Ce volume constitue les actes de la table ronde qui s'est tenue les 15 et 16 novembre 2007 à la Maison Méditerranéenne des Sciences de l'Homme d'Aix-en-Provence, et qui a été organisée dans le cadre du GDR 2992 du CNRS, JurAlpes, sur le thème " Dynamique holocène de l'environnement dans le Jura et les Alpes : du climat à l'homme ". Les dix huit contributions rassemblées dans cet ouvrage couvrent un large éventail de champs disciplinaires et de méthodes d'étude. Après les deux premiers chapitres dédiés successivement aux reconstitutions des fluctuations des glaciers des Alpes occidentales depuis 5000 ans (P. Deline et M. Le Roy) et à l'usage des spéléothèmes en tant que proxy de la variabilité climatique annuelle (Y. Perrette), les cinq contributions suivantes s'appuient sur l'analyse de séquences sédimentaires lacustres (E. Chapron et al. ; M. Magny et al. ; L. Millet et al. ; F. Arnaud et al. ; A. Leroux et al.). Les lacs étudiés sont des lacs d'altitude (lac de Joux dans le Jura, lacs d'Anterne, de Bramant, de Blanc Huez et de Dessus-Verney dans les Alpes), ou des grands lacs de vallées (lacs du Bourget et de Constance, ou Bodensee). Suivent quatre chapitres qui s'intéressent aux vecteurs fluviatiles, de la vallée du Rhône (J.-P. Bravard et al. ; J.-F. Berger et al.), au bassin de la Durance (C. Miramont et al.) jusqu'au delta du Rhône (C. Vella et al.). Viennent ensuite trois contributions qui sont plus particulièrement centrées sur l'histoire du couvert végétal et de la pédogénèse dans les zones d'altitude des Alpes en s'appuyant sur des données anthracologiques (B. Talon), dendrochronologiques (J.-L. Edouard et A. Thomas) et pédo-sédimentaires (B. Moulin et P.-J. Rey). Enfin, les quatre dernières contributions portent sur l'histoire de l'anthropisation des Alpes (P.J. Rey et al. ; P. Bintz et al. ; A. Marguet et al. ; F. Mocci et al.) et du Jura (E. Gauthier et H. Richard)