Propagative Deployment of Hierarchical Components in a Dynamic Network

International audienceThis paper addresses the distribution and the deployment of hierarchical components on heterogeneous dynamic networks. Such networks may include fixed and mobile resource-constrained devices and are characterized by the volatility of their hosts and connections, which may lead to their fragmentation. We propose a propagative, hierarchically-controlled deployment process for such networks and an ADL extension allowing the specification of this context-aware deployment

Performance Evaluation of Automatically Generated Data Parallel Programs

International audienceIn this paper, the problem of evaluating the performance of parallel programs generated by data parallel compilers is studied. These compilers take as input an application written in a sequential language augmented with data distribution directives and produce a parallel version based on the specifed partitioning of data. A methodology for evaluating the relationships existing among the program characteristics, the data distribution adopted, and the performance indices measured during the program execution is described. It consists of three phases: a "static" description of the program under study, a "dynamic" description, based on the measurement and the analysis of its execution on a real system, and the construction of a workload model, by using workload characterization techniques. Following such a methodology, decisions related to the selection of the data distribution to be adopted can be facilitated. The approach is exposed through the use of the Pandore environment, designed for the execution of sequential programs on distributed memory parallel computers. It is composed of a compiler, a runtime system and tools for trace and profile generation. The results of an experiment explaining the methodology are presented

POM: a Virtual Parallel Machine Featuring Observation Mechanisms

International audienceWe describe in this paper a Parallel Observable virtual Machine (POM), which provides a homogeneous interface upon the communication kernels of parallel architectures. POM was designed so as to be ported easily and eciently on numerous parallel platforms. It provides sophisticated features for observing distributed executions

CoAP over BP for a Delay-Tolerant Internet of Things

International audienceWith the advent of the Internet of Things (IoT) a myriad of new devices will become part of our everyday life. Constrained Application Protocol (CoAP), and its extensions, are specifically designed to address the integration of these constrained devices. However, due to their limited resources, they are often unable to be fully connected and instead form intermittently connected and sparse networks in which Delay Tolerant Networking (DTN) is more appropriate, in particular through the Bundle Protocol (BP). This paper addresses the implementation of a BP binding for CoAP as a means to enable Delay Tolerant IoT. After an overview of CoAP and BP, we present a basic implementation of CoAP/BP that we developed and some first experimentation results that validate the feasibility of the approach. Several leads are then explored regarding ways to take advantage of the BP features in order to achieve an optimized CoAP/BP implementation

Automated deployment of enterprise systems in large-scale environments

International audienceThe deployment of multi-tiered applications in large-scale environments remains a difficult task: the architecture of these applications are complex and the target environment is heterogeneous, open and dynamic. In this paper, we show how the component-based approach simplifies the design, the deployment and the reconfiguration of a J2EE system. We propose an architecture description language that allows specifying the resources and location constraints and a deployment solution that handles failures

Middleware support for delay-tolerant service provision in disconnected mobile ad hoc networks

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Self-lubricating polymer composites : using numerical trbology to hightlight their design criterion

International audienceAfter the cessation of RT/Duroid 5813, manufacturing tests were performed by CNES and ESA/ESTL in order to find an alternative material. Although PGM-HT was selected as the best candidate, limitations about its tribological capabilities to replace RT/Duroid 5813 were later pointed out. Today, the predictability of the tribological behaviour of those materials is not fully overcome. The motivation to this work is to complement studies of self-lubricating materials by coupling experimental analyses with numerical modelling, in order to predict their tribological behaviour. A Discrete Element Method is chosen to construct the numerical material, because it allows to represent wear and the third body generation at the scale of the ball/retainer contact. An underlying role of the adhesion between components in controlling the tribological properties of the transfer film has been observed

Self-lubricating composite bearings: Effect of fibre length on its tribological properties by DEM modelling

International audienceSelf-lubricating polymer-based composites are used in space and in aircraft mechanisms as materials for solid lubricated systems. Such composites mostly consist of a polymeric matrix and fillers of two kinds: hard fillers (fibres made of glass, or of minerals) and solid lubricating particles (made of MoS 2). Their advantages are that they provide their own lubrication, and they can be used in both very high and very low temperatures (from −40 up to ~200 F). Precision ball bearings with these composites are manufactured since the 60's in these bearings the retainer material itself provides the lubrication. From the experimental analyses implemented (X-ray tomography, SEM observations, and experiences in a tribometer); it is possible to observe that the geometry of the fillers has a strong influence on the third body rheology. Nevertheless, the confined nature of the contact does not allow in-situ observation. To overcome this difficulty a combined numerical/experimental approach is carried out. To be able to reproduce the evolution of third-body particles within the contact, Discrete Element Methods (DEM) is used. Such an approach allows to represent wear: by the construction of an equivalent continuous medium resulting from the incorporation of interaction laws between the discrete particles. The motivation to this work is the understanding of the impact of filler geometry o tribological behaviour of these materials. More specifically, the goal is to study the influence of the fibre length in the tribological behaviour of self-lubricating composites by Discrete Element Methods (DEM)

TAO: A Time-Aware Opportunistic Routing Protocol for Service Invocation in Intermittently Connected Networks

International audienceHandheld devices owned by nomadic people can form intermittently connected mobile ad hoc networks spontaneously. Such networks appear as an attractive solution for service providers, such as local authorities, in order to extend a pre-existing infrastructure-based network composed of several infostations so as to provide nomadic people with application services in a large scale area (e.g., a city). In such hybrid networks, intermittent connections are prevalent, and end-toend paths between clients and providers cannot be maintained all the time. Service provisioning thus remains a challenging problem today in these networks. In this paper, we propose a new time-aware opportunistic routing protocol called TAO. TAO is designed for service invocation in intermittently connected hybrid networks. This protocol makes it possible to select the best next message forwarder(s) among a set of neighbor nodes based on the dates of contacts of these nodes with infostations, and tends to implicitly estimate the distance separating these mobile nodes and the infostations. This paper gives a detailed description of this protocol supported with some simulation results

Parallel Program Performance Debugging with the Pandore II Environment

International audienceIn this paper, we present the overall design of Pandore II, an Environment dedicated to the experimentation of distribution of sequential programs for their execution on distributed memory parallel architectures. The emphasis is then put on two performance analysis tools integrated in this environment