Méthode de raccord multi-domaines non-conforme pour des écoulements multiphasiques

Une méthode multi-domaines non conforme, basée sur des méthodes multi-grilles développées sur des schémas ICE, est décrite. Cette méthode a été validée sur des cas test de convection de jet de gaz 2D plan. Les résultats de simulation obtenus dans le cas des simulations multi-domaines non conforme sont identiques aux cas standard. Cette méthode multi-domaines non conforme peut s'appliquer à des cas multi-domaines, des cas de raffinement local ou des cas multi-grilles. Cette méthode peut s'étendre aux autres applications pour simuler des écoulements multiphasiques

ubiSOAP: A Service Oriented Middleware for Ubiquitous Networking

International audienceThe computing and networking capacities of today's wireless portable devices allow for ubiquitous services, which are seamlessly networked. Indeed, wireless handheld devices now embed the necessary resources to act as both service clients and providers. However, the ubiquitous networking of services remains challenged by the inherent mobility and resource constraints of the devices, which make services a priori highly volatile. This paper discusses the design, implementation and experimentation of the ubiSOAP service-oriented middleware, which leverages wireless networking capacities to effectively enable the ubiquitous networking of services. ubiSOAP specifically defines a layered communication middleware that underlies standard SOAP-based middleware, hence supporting legacy Web Services while exploiting nowadays ubiquitous connectivity

Interoperability of Service Discovery Protocols: Transparent versus Explicit Approaches

International audienceDiscovering networked services in pervasive computing environments is problematic as multiple Service Discovery Protocols (SDPs), differing on their services description formats as well as advertisement and request models, have already become (de-facto) standards. This calls for a solution to SDP interoperability, enabling clients to locate networked services independent of the SDP they use to advertise their presence. In this paper, we report on our experience in developing two such solutions: the transparent approach of INDISS based on message translation, and the explicit approach of MSDA based on protocol integration. While efficient and able to support legacy clients and services, INDISS is limited by the basic service information available in existing SDPs, and assumptions about the network protocols used by the SDPs. Advanced discovery features required by pervasive environments, such as context or security management, can only be provided by more complex discovery frameworks like MSDA, but come at a price

Evolution of Bacterial Phosphoglycerate Mutases: Non-Homologous Isofunctional Enzymes Undergoing Gene Losses, Gains and Lateral Transfers

The glycolytic phosphoglycerate mutases exist as non-homologous isofunctional enzymes (NISE) having independent evolutionary origins and no similarity in primary sequence, 3D structure, or catalytic mechanism. Cofactor-dependent PGM (dPGM) requires 2,3-bisphosphoglycerate for activity; cofactor-independent PGM (iPGM) does not. The PGM profile of any given bacterium is unpredictable and some organisms such as Escherichia coli encode both forms.To examine the distribution of PGM NISE throughout the Bacteria, and gain insight into the evolutionary processes that shape their phyletic profiles, we searched bacterial genome sequences for the presence of dPGM and iPGM. Both forms exhibited patchy distributions throughout the bacterial domain. Species within the same genus, or even strains of the same species, frequently differ in their PGM repertoire. The distribution is further complicated by the common occurrence of dPGM paralogs, while iPGM paralogs are rare. Larger genomes are more likely to accommodate PGM paralogs or both NISE forms. Lateral gene transfers have shaped the PGM profiles with intradomain and interdomain transfers apparent. Archaeal-type iPGM was identified in many bacteria, often as the sole PGM. To address the function of PGM NISE in an organism encoding both forms, we analyzed recombinant enzymes from E. coli. Both NISE were active mutases, but the specific activity of dPGM greatly exceeded that of iPGM, which showed highest activity in the presence of manganese. We created PGM null mutants in E. coli and discovered the ΔdPGM mutant grew slowly due to a delay in exiting stationary phase. Overexpression of dPGM or iPGM overcame this defect.Our biochemical and genetic analyses in E. coli firmly establish dPGM and iPGM as NISE. Metabolic redundancy is indicated since only larger genomes encode both forms. Non-orthologous gene displacement can fully account for the non-uniform PGM distribution we report across the bacterial domain

A flexible QoS-aware routing protocol for infrastructure-less B3G networks

International audienceCurrent mobile devices support multiple network technolo- gies and network composition via such devices can enable service provisioning across heterogeneous networks. One of the key challenges for realizing this view is inter-domain routing. Indeed, given the diversity of involved network technologies and infrastructures, a exible routing protocol that takes into account their quality properties and dynam- ics is an important requirement. In this paper, we present a exible quality-aware routing protocol for infrastructure-less B3G environments that enables discovery of routes with op- timal bandwidth, delay or cost according to the preference of each client. The protocol is based on the Optimized Link- State Routing (OLSR) protocol and is designed to enable computation of quality-aware routes in multi-network envi- ronments. We detail the protocol, discuss its deployment and provide experimental results

Interoperable Semantic & Syntactic Service Matching for Ambient Computing Environments

International audienceThe inherent heterogeneity of ambient computing environments and their constant evolution requires middleware platforms to manage networked components designed, developed and deployed independently. Such management must also be efficient to cater for resource-constrained devices and highly dynamic situations due to the spontaneous appearance and disappearance of networked resources. For service discovery protocols (SDP), one of the main functions of service-oriented architectures (SOA), the efficiency of the matching of syntactic service descriptions is most often opposed to the fullness of the semantic approach. As part of the PLASTIC middleware for ambient computing environments, we present in this paper an interoperable service matching and ranking platform, which is able to process service descriptions from both semantic and syntactic service description languages. To that end, we define a generic, modular description language able to record service functional properties, potentially extended with semantic annotations. An evaluation of the prototype implementation of our platform demonstrates that multi-protocols service matching supporting various levels of expressiveness can be achieved in ambient computing environments

Dos and Don'ts in Mobile Phone Sensing Middleware: Learning from a Large-Scale Experiment

International audienceMobile phone sensing contributes to changing the way we approach science: massive amount of data is being contributed across places and time, and paves the way for advanced analyses of numerous phenomena at an unprecedented scale. Still, despite the extensive research work on enabling resource-efficient mobile phone sensing with a very-large crowd, key challenges remain. One challenge is facing the introduction of a new heterogeneity dimension in the traditional middleware research landscape. The middleware must deal with the heterogeneity of the contributing crowd in addition to the system's technical heterogeneities. In order to tackle these two heterogeneity dimensions together, we have been conducting a large-scale empirical study in cooperation with the city of Paris. Our experiment revolves around the public release of a mobile app for urban pollution monitoring that builds upon a dedicated mobile crowd-sensing middleware. In this paper, we report on the empirical analysis of the resulting mobile phone sensing efficiency from both technical and social perspectives, in face of a large and highly heterogeneous population of participants. We concentrate on the data originating from the 20 most popular phone models of our user base, which represent contributions from over 2,000 users with 23 million observations collected over 10 months. Following our analysis, we introduce a few recommendations to overcome-technical and crowd-heterogeneities in the implementation of mobile phone sensing applications and supporting middleware

Efficient Context-aware Service Discovery in Multi-Protocol Pervasive Environments

International audienceService discovery is a critical functionality of emerging pervasive computing environments. In such environments, service discovery mechanisms need to (i) overcome the heterogeneity of hardware devices, software platforms, and networking infrastructures; and (ii) provide users with an accurate selection of services that meet their current requirements. To address these issues, we have developed the Multi- Protocol Service Discovery and Access (MSDA) middleware platform2, which provides context-aware service discovery and access in pervasive environments. This paper primarily focuses on the design and implementation of the context-awareness support of MSDA. Context-awareness not only provides a more accurate service selection, but also enables a more efficient dissemination of service requests across heterogeneous pervasive environments. We present the design and prototype implementation of MSDA, along with experimental results that demonstrate the advantages derived by introducing context awareness