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- PublicationMétadonnées seulementA Roadmap for Research in Sustainable Ultrascale Systems(Bruxelles: EU-COST IC1305, 2018)
;Sousa, Leonel ; ;Kuonen, Pierre ;Prodan, Radu ;Trinh, Tuan AnhCarreto, JesusThe COST Action IC1305 (NESUS) proposes in this research roadmap research objectives and twelve associated recommendations, which in combination, can help bring about the notable changes required to make true the existence of sustainable ultrascale computing systems. Moreover, they are useful for industry and stakeholders to define a path towards ultrascale systems.
- PublicationMétadonnées seulementSPINET: A Parallel Computing Approach to Spine Simulations(1996-1-22)
; ;Lederer, Edgar F. A. ;Steffen, Thomas ;Guggisberg, Karl ;Schneider, Jean-GuySchwab, PeterResearch in scientitic programming enables us to realize more and more complex applications, and on the other hand, application-driven demands on computing methods and power are continuously growing. Therefore, interdisciplinary approaches become more widely used. The interdisciplinary SPINET project presented in this article applies modern scientific computing tools to biomechanical simulations: parallel computing and symbolic and modern functional programming. The target application is the human spine. Simulations of the spine help us to investigate and better understand the mechanisms of back pain and spinal injury. Two approaches have been used: the first uses the finite element method for high-performance simulations of static biomechanical models, and the second generates a simulation developmenttool for experimenting with different dynamic models. A finite element program for static analysis has been parallelized for the MUSIC machine. To solve the sparse system of linear equations, a conjugate gradient solver (iterative method) and a frontal solver (direct method) have been implemented. The preprocessor required for the frontal solver is written in the modern functional programming language SML, the solver itself in C, thus exploiting the characteristic advantages of both functional and imperative programming. The speedup analysis of both solvers show very satisfactory results for this irregular problem. A mixed symbolic-numeric environment for rigid body system simulations is presented. It automatically generates C code from a problem specification expressed by the Lagrange formalism using Maple.
- PublicationMétadonnées seulementDynamic Load Sharing in Peer-to-Peer Systems? When Some Peers Are More Equal than Others(2006-5-1)
;Serbu, Sabina ;Bianchi, Silvia ;
- PublicationAccès libreSimulation of communities of nodes in a wide area distributed system(2001)
;Yuen, Saiho ; ;Unger, HerwigBabin, GilbertThe complex structure of the Web requires decentralised, adaptive mechanisms efficiently providing access to local and global capacities. To facilitate the development of such mechanisms, it seems to be reasonable to build clusters or grids of machines with similar structures and interests. In such a manner, communities of machines can be built. In a community, every machine contributes to the overall success through a division of management work and a respective collaboration. This article presents and analyses experimental results for algorithms optimising service response times in a community. We introduce a community simulation tool, which is used to experiment with optimisation algorithms. The experimentation results are presented and analysed.
- PublicationMétadonnées seulementBalls simulator: Evaluator of a structured peer-to-peer system with integrated load balancing(2006)
;Le, Viet Dung ;Babin, GilbertSimulation is an efficient way to evaluate new peer-to-peer models. It requires two implicit properties: large scale and high dynamicity. In the context of our work that proposes a peer-to-peer structure based on partitioning a de Bruijn graph and its load balancing algorithms, we developed a simulator for evaluation purposes. This paper introduces a three- layer architecture of the simulator. This architecture allows to support simulations in two modes: centralized (where all peers are simulated on one physical machine) and decentralized (where the peers run on separate machines communicating through the underlying network).
- PublicationAccès libreTowards an agent-basedapproach for multimarket package e-procurement(2002)
;Benameur, Houssein ;Vaucher, Stéphane ;Gérin-Lajoie, Robert ;Chaib-draaa, BrahimWhile most e-commerce research focuses on one market based problems, less work has been done on mul-timarket aggregation. Nowadays it is important to address the multimarket package e-procurement problem if we want to acquire a combination of goods and services from different suppliers and service providers. To achieve this, one should address the issues pertaining to identifying of a company's needs, discovering poten-tial partners and suppliers, gathering distributed information and conducting combined negotiations, creating a seamless of information flow with different heterogeneous markets, suppliers, and partners, and finally con-cluding transactions. Several commercial e-procurement applications already automate some aspects of the procurement processes, helping decision makers and employees complete their purchasing activity. But none take into account the key aspects of combining goods and services into one aggregated package. Agent-based systems are well equipped to address the challenges of multimarket package e-procurement. Indeed, goal driven autonomous agents aim to satisfy user requirements and preferences while being flexible enough to deal with the diversity of semantics amongst markets, suppliers, service providers, partners and individual sellers. A dis-tributed common shared space, called infospace, comprised of the negotiation exchanges and states, allows for agent coordination, market aggregation, and packages construction. This paper presents some issues and chal-lenges faced in multimarket package e-procurement, and puts forward an agent-based approach to deal with them.
- PublicationAccès libreIntensional Communities(1999)
;Plaice, JohnWe describe the interaction and relation between entities in distributed systems, as proposed in the Web Operating System (WOS). Every entity in the system is a versioned object which depends on its current context, which itself is pro- grammable and can be effected by the objects circulating within it. These entities interact through mechanisms of requests/answers and negotiations. Those who exhibit functional and behavioral affinities may dynamically associate themselves to form communities. This positional paper states the basic ideas of the notion of communities in distributed systems.
- PublicationMétadonnées seulementDynamic server selection in distributed object computing systemsIn this paper, we address the problem of dynamic server selection among a set of objectservers, as the ones defined by CORBA and DCOM, providing the same service type. Theseservers are not necessarily replicas but may have different interfaces and belong to differentservice providers. As a solution, we propose a novel architecture that we call LoDACE. Thisarchitecture has been designed to allow dynamic server selection and load sharing indistributed object computing environments. Specifically, the architecture prevents theoccurrence of major load imbalances that can cause failures in distributed applications. Thearchitecture is based on both the use of a trading service and the monitoring of the servers’load. Our interest in the trader is motivated by the need to discover object serversdynamically. LoDACE allows service requests to be processed by lightly loaded serversselected dynamically. The expected results are better performances in terms of responsivenessand availability of servers.
- PublicationMétadonnées seulementLessons Learned from Applying Big Data Paradigms to a Large Scale Scientific Workflow(: CEUR-WS.org, 2016-11-14)The increasing amount of data related to the execution of scientific workflows has raised awareness of their shift towards parallel data-intensive problems. In this paper, we deliver our experience with combining the traditional high-performance computing and grid-based approaches for scientific workflows, with Big Data analytics paradigms. Our goal was to assess and discuss the suitability of such data-intensive-oriented mechanisms for production-ready workflows, especially in terms of scalability, focusing on a key element in the Big Data ecosystem: the data-centric programming model. Hence, we reproduced the functionality of a MPI-based iterative workflow from the hydrology domain, EnKF-HGS, using the Spark data analysis framework. We conducted experiments on a local cluster, and we relied on our results to discuss promising directions for further research.
- PublicationMétadonnées seulementLoDACE: une architecture de partage de charge dans les systèmes distribués objet