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Évry, France

Contejean E.,CNRS Computer Science Laboratory | Contejean E.,University Paris - Sud | Contejean E.,French Institute for Research in Computer Science and Automation | Courtieu P.,French National Conservatory of Arts and Crafts | And 5 more authors.
Leibniz International Proceedings in Informatics, LIPIcs | Year: 2011

We present the rewriting toolkit CiME3. Amongst other original features, this version enjoys two kinds of engines: to handle and discover proofs of various properties of rewriting systems, and to generate Coq scripts from proof traces given in certification problem format in order to certify them with a sceptical proof assistant like Coq. Thus, these features open the way for using CiME3 to add automation to proofs of termination or confluence in a formal development in the Coq proof assistant. © Évelyne Contejean, Pierre Courtieu, Julien Forest, Olivier Pons, Xavier Urbain. Source

Peru S.,CEA DAM Ile-de-France | Gosselin G.,CEA DAM Ile-de-France | Martini M.,CEA DAM Ile-de-France | Dupuis M.,CEA DAM Ile-de-France | And 2 more authors.
Physical Review C - Nuclear Physics | Year: 2011

Fully consistent axially-symmetric deformed quasiparticle random-phase approximation (QRPA) calculations have been performed, using the same Gogny D1S effective force for both the Hartree-Fock-Bogolyubov mean field and QRPA matrix. New implementation of this approach leads to the applicability of QRPA to heavy deformed nuclei. Giant resonances and low-energy collective states for monopole, dipole, quadrupole, and octupole modes are predicted for the heavy deformed nucleus U238 and compared with experimental data. © 2011 The American Physical Society. Source

Chendeb Taher N.,Lebanese University | Ghamri Doudane Y.,ENSIIE | El Hassan B.,Lebanese University | Agoulmine N.,University of Evry Val dEssonne
Computer Communications | Year: 2014

Supporting emergent voice/video applications in all wireless technologies is a requirement in the Next Generation Network (NGN) where Wireless Local Area Networks (WLANs) is a main component. For this type of applications, QoS needs to be fully maintained in order to assure user satisfaction. Actually, QoS control in 802.11e WLANs to support real time voice/video services remains an open problem. All the solutions that only aim to enhance the performance of the Enhanced Distributed Channel Access (EDCA) mechanism cannot resolve the performance degradation problem once the channel becomes saturated. Hence, an efficient admission control scheme in EDCA is the key to guarantee the QoS required by voice/video services in WLANs. In this paper, we propose a model-based admission control algorithm that is located within the QoS Access Point (QAP). An accurate analytical model is used to predict the QoS metrics that can be achieved once a new flow is introduced in the WLAN. Based on this prediction and on the QoS constraints of already admitted (active) flows as well as of the new flow, the QAP takes the appropriate decision for the new flow. The proposed admission control scheme is fully compatible with the legacy 802.11e EDCA MAC protocol. It is validated numerically and through simulations using several realistic usage scenarios. © 2013 Elsevier B.V. All rights reserved. Source

Haddadou K.,University Pierre and Marie Curie | Ghamri-Doudane S.,Alcatel - Lucent | Ghamri-Doudane Y.,ENSIIE | Agoulmine N.,University of Evry Val dEssonne
International Journal of Network Management | Year: 2012

Today the policy-based management (PBM) approach is recognized as an efficient solution to simplify the complex task of managing and controlling networks. To this end, the Internet Engineering Task Force (IETF) has introduced a reference framework to build PBM systems. However, this framework only addresses the provisioning of relatively long validity period services based on predefined service-level agreements. Furthermore, very little work addresses the scalability properties of the instantiation of this framework in a real network. This work aims to extend the IETF PBM framework in order to support dynamic provisioning of short-term services (end-system signalling) as well as an instantiation scheme that is scalable (distributed provisioning of edge routers). This instantiation scheme is based on the distribution of the provisioning process while keeping centralized only the parts that involve critical resources, namely bandwidth brokerage. The performance properties of the proposed scheme are then demonstrated throughout both extensive experimentation and an analytical study. The extension of this performance analysis to the case where multiple bandwidth brokers are used is also discussed. The results of this work are intended to be used as a guideline to help network operators to design a scalable PBM system in order to offer to their customers services with quality of service assurance on an on-demand basis. Copyright © 2011 John Wiley & Sons, Ltd. Source

Billionnet A.,ENSIIE
Operational Research | Year: 2010

Forest fragmentation occurs when large and continuous forests are divided into smaller patches. This fragmentation may result from natural processes, urban development, agricultural use, and timber harvesting. Many studies have shown that forest fragmentation have led to global biodiversity loss, hence forestry management needs to explicitly incorporate spatial ecology objectives. Given a set of forest patches distributed on a landscape, the fragmentation can be measured by many indicators. In this paper, we consider the three usual following indicators: the mean proximity index, the mean nearest neighbour distance, and the mean shape index. In a fragmented forest landscape, a natural objective is to select a subset of patches satisfying some constraints such as area constraint, and optimal regarding these indicators with the aim of protecting biodiversity. These optimisation problems have been already studied in the literature by heuristic methods. However, these algorithms which generally are fast and provide good solutions, have significant drawbacks. In this paper, we propose an original 0-1 linear programming formulation of the search for a subset of patches minimising the sum of the distances between every patch and its closest neighbour. Using this formulation, we show that it is possible to efficiently optimise forest patch selection in a landscape with regards to the previous metrics. The optimising procedure is based on integer fractional programming and integer linear programming. The mathematical programming models are simple. The implementations are immediate by using a mathematical programming language and integer linear programming software. And the computational experiments, carried out on simulated landscapes comprising up to 200 patches, show that the performance of this approach is excellent: A few seconds of computation are sufficient to find an optimal solution to each patch selection problem. © Springer-Verlag 2009. Source

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