La prise en compte et la correction des effets induits dans les images par les détecteurs du plan focal (CCD) a été identifié comme étant un point essentiel pour remplir les objectifs scientifiques de la collaboration LSST- Dark Energy Science Collaboration. Le groupe de travail SAWG a été crée, et des bancs optique ont été mis à contribution dans certains laboratoires de la collaboration (UC Davis, SLAC, BNL et LPNHE) afin d'adresser le problème. LSST fait partie d'une nouvelle catégorie de télescopes : les grands plans focaux. Depuis une dizaine d'années que ceux-ci sont équipés de CCD à haute résistivité, un certain nombre de nouveaux effets ont été identifiés. Une attention toute particulière est portée sur la compréhension des distorsions électrostatiques inhérentes aux propriétés du CCD qui ont un impact sur les mesures de science. Le travail de cette thèse est centré sur l'étude de l'effet brighter-fatter et des tree-rings. Il a été démontré qu'avec certains types d'illuminations, il était possible de caractériser ces effets avec précision. C'est dans le but de produire ces illuminations qu'un projecteur de franges a été développé sur le banc optique du LPNHE. Dans ce document sont ainsi présentés : une nouvelle méthode de caractérisation des tree- rings testée sur des simulations ; une nouvelle méthode de mesure de l'effet brighter-fatter basée sur la projection de profils de Ronchi ; une étude complète des différentes propriétés de l'effet brighter-fatter dans laquelle a été mis en place un modèle électrostatique simplifié. Enfin, l'efficacité d'une méthode de correction, dite de descrambling est évaluée. / The removal of the sensor signature in the science images has been identified by the LSST Dark Energy Science Collaboration as a mandatory path to fullfill its scientific goals. The SAWG working group has been put together to perform this task for the collaboration. It has access to optical benches in some of the laboratories of the collaboration (UC Davis, SLAC, BNL and LPNHE) for this purpose. LSST belongs to a new category of telescopes equiped with large focal planes. For the decade that they have been equipped with thick, high resistivity Charge Coupled Devices (CCD), new effects have been identified. A particular attention is given to the understanding of the electrostatic distortions that are inherent to the CCD properties. These electrostatic distortions have an impact on science measurements. My PhD work is centered on the study of the brighter-fatter effect and the tree-rings. It has been shown that with different kind of illuminations, it was possible to accurately characterize these effects. A fringe projector has been developed on the optical bench of the LPNHE in order to produce these particular illuminations. In this document, we present : a new method, tested on simulations, to characterize the tree-rings; a new method to measure the brighter-fatter effect based on the projection of Ronchi profiles; a complete study of the different properties of the brighter-fatter effect, where we developped a simplified electrostatic model. Finally, the efficiency of a correction method, called descrambling, is evaluated.

Service-oriented architectures are a popular architectural paradigm for building software applications from a number of loosely coupled, distributed services. Through a set of procedural rules, workflow technologies define how groups of services coordinate with one another to achieve a shared task. A problem with workflow specifications is that often the patterns of interaction between the distributed services are too complicated to predict and analyse at design-time. In certain cases, the exact patterns of message exchange and the concrete services to call cannot be predicted in advance, due to factors such as fluctuating network load or the availability of services. It is a more realistic assumption to endow software components with the ability to make decisions about the nature and scope of their interactions at runtime. Multiagent systems offer a complementary paradigm: building software applications from a number of self interested, autonomous agents. This thesis presents an investigation into fusing the agency and service-oriented architecture paradigms, in order to facilitate flexible, workflow composition. Our approach offers an agent-based solution to service choreography and is founded on the concept of shared interaction protocols. By adopting an agent-based approach to service choreography, active autonomous agents can utilise the typically passive service-oriented architectures, found in Internet and Grid systems. In contrast with statically defined, centralised service orchestrations, decentralised agents can perform service choreography at runtime, allowing them to operate in scenarios where it is not possible to define the pattern of interaction in advance. Application to real scenarios is a driving factor behind this research. By working closely with a number of active Grid projects, namely AstroGrid and the Large-Synoptic Survey Telescope (LSST), a concrete set of requirements for scientific workflow have been derived, based on realistic science problems. This research has resulted in the MultiAgent Service Choreography (MASC) language to express scientific workflow, methodology for system building and a software framework which performs agent based Web service choreography, in order to enact distributed e-Science experiments. Evaluation of this thesis is conducted through case study, applying the language, methodology and software framework to solve a motivating set of workflow scenarios.

Philosophiae Doctor - PhD / The next generation of radio telescopes will revolutionize cosmology by providing large three-dimensional surveys of the universe. This work presents forecasts using the technique 21cm intensity mapping (IM) combined with results from the cosmic microwave background, or mock data of galaxy surveys. First, we discuss prospects of constraining curvature independently of the dark energy (DE) model, finding that the radio instrument HIRAX will reach percent-level accuracy even when an arbitrary DE equation of state is assumed. This is followed by a study of the potential of the multi-tracer technique to surpass the cosmic variance limit, a crucial method to probe primordial non-Gaussianity and large scale general relativistic e↵ects. Using full sky simulations for the Square Kilometre Array phase 1 (SKA 1 MID) and the Large Synoptic Survey Telescope (LSST), including foregrounds, we demonstrate that the cosmic variance contaminated scenario can be beaten even in the noise free case. Finally, we derive the signal to noise ratio for the cosmic magnification signal from foreground HI intensity maps combined with background galaxy count maps. Instruments like SKA1 MID and HIRAX are highly complementary and well suited for this measurement. Thanks to the powerful design of the planned radio instruments, all results confirm their potential and promise an exciting future for cosmology.