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Item Providing Reliability for Transactional Mobile Agents(Vincent Guyot, 2013) Zeghache, Linda; Hurfin, Michel; Moise, Izabela; Badache, NadjibA transactional agent is a mobile agent that migrates from a site to another one in order to execute a distributed transaction assigned by a user. Works on transactional mobile agents have identified two prob- lems that can not be solved by the agent alone. The first one is related to the reliability. The lack of a fault tolerant infrastructure and method- ologies that address fault tolerant execution of mobile agents highlights a major drawback of this technology. The second problem for which the agent needs assistance is related to the atomic validation of the transac- tion. In this paper we address the mobile agent fault tolerance and the transactional supportItem Special Issue on Interconnections of Wireless Sensor Networks(InderScience, 2011-05) Derhab, Abdelouahid; Djenouri, Djamel; Jianguo, DingItem An Ω-Based Leader Election Algorithm for Mobile Ad Hoc Networks(Springer Berlin Heidelberg, 2012) Melit, Leila; Badache, NadjibLeader election is a fundamental control problem in both wired and wireless systems. The classical statement of the leader election problem in distributed systems is to eventually elect a unique leader from a fixed set of nodes. However, in MANETS, many complications may arise due to frequent and unpredictable topological changes. This paper presents a leader election algorithm based on the omega failures detector, where inter-node communication is allowed only among the neighboring nodes along with proofs of correctness. This algorithm ensures that every connected component of the mobile ad hoc network will eventually elect a unique leader, which is the node of the highest priority value from among all nodes within that connected component. The algorithm can tolerate intermittent failures, such as link failures, network partitions, and merging of connected network components.Item Semantic Annotations and Context Reasoning to Enhance Knowledge Reuse in e-Learning(Springer Berlin Heidelberg, 2013) Boudebza, Souad; Berkani, Lamia; Azouaou, Faiçal; Nouali, OmarWe address in this paper the need of improving knowledge reusability within online Communities of Practice of E-learning (CoPEs). Our approach is based on contextual semantic annotations. An ontological-based contextual semantic annotation model is presented. The model serves as the basis for implementing a context aware annotation system called “CoPEAnnot”. Ontological and rule-based context reasoning contribute to improving knowledge reuse by adapting CoPEAnnot’s search results, navigation and recommendation.The proposal has been experimented within a community of learners.Item A Formal Approach for a Self Organizing Protocol Inspired by Bacteria Colonies: Production System Application(Springer Berlin Heidelberg, 2010) Mellah, Hakima; Hassas, Salima; Drias, Habiba; Raiah, A.; Tiguemoumine, A.Any dysfunction in production system (PS) is likely to be very expensive; so modelling by Multi Agent Systems (MAS) makes the production system (PS) possible to have aspects of robustness, reactivity and flexibility, which allow the PS control to be powerful and to react to all the risks being able to occur. In order to have a fault-tolerant PS, we propose when and how to recourse to a self organizing protocol making the MAS capable of changing its communication structure or organization, and thus reorganizing itself without any external intervention.Item Tags Weighting Based on User Profile(Springer Berlin Heidelberg, 2011) Kichou, Saida; Mellah, Hakima; Amghar, Youssef; Dahak, FouadThe ’Collaborative Tagging’ is gaining popularity on Web 2.0, this new generation of Web which makes user reader/writer. The ’Tagging’ is a mean for users to express themselves freely through additions of label called ’Tags’ to shared resources. One of the problems encountered in current tagging systems is to define the most appropriate tag for a resource. Tags are typically listed in order of popularity, as del-icio-us. But the popularity of the tag does not always reflect its importance and representativeness for the resource to which it is associated. Starting from the assumptions that the same tag for a resource can take different meanings for different users, and a tag from a knowledgeable user would be more important than a tag from a novice user, we propose an approach for weighting resource’s tags based on user profile. For this we define a user model for his integration in the tag weight calculation and a formula for this calculation, based on three factors namely the user, the degree of approximation between his interest centers and the resource field, expertise and personal assessment for tags associated to the resource. A resource descriptor containing the best tags is created.Item Multi-Agent Liquidity Risk Management in an Interbank Net Settlement System(Springer Berlin Heidelberg, 2012) Hedjazi Dellal, Badiâa; Ahmed-Nacer, Mohamed; Aknine, Samir; Benatchba, KarimaA net settlement system is a payment system between banks, where a large number of transactions are accumulated, usually waiting until the end of each day to be settled through payment instruments like: wire transfers, direct debits, cheques, .... These systems also provide clearing functions to reduce interbank payments but are sometimes exposed to liquidity risks. Monitoring, and optimizing the interbank exchanges through suitable tools is useful for the proper functioning of these systems. The goal is to add to these systems an intelligent software layer integrated with the existing system for the improvement of transactions processing and consequently avoid deadlock situations, deficiencies and improve system efficiency. We model and develop by multi-agent an intelligent tracking system of the interbank exchanged transactions to optimize payments settlement and minimize liquidity risks.Item Reducing Thread Divergence in GPU-Based B&B Applied to the Flow-Shop Problem(Springer Berlin Heidelberg, 2012) Chakroun, Imen; Bendjoudi, Ahcène; Melab, NouredineIn this paper,we propose a pioneering work on designing and programming B&B algorithms on GPU. To the best of our knowledge, no contribution has been proposed to raise such challenge. We focus on the parallel evaluation of the bounds for the Flow-shop scheduling problem. To deal with thread divergence caused by the bounding operation, we investigate two software based approaches called thread data reordering and branch refactoring. Experiments reported that parallel evaluation of bounds speeds up execution up to 54.5 times compared to a CPU version.Item A Comparison on MANETs’ Service Replication Schemes: Interest versus Topology Prediction(Springer, 2010) Derhab, Abdelouahid; Hamdy, Mohamed; König-Ries, BirgittaMobile ad hoc networks (MANETs) are characterized by high dynamics in particular with respect to the formation of network partitions. The presence of unconnected partitions makes the deployed services inaccessible to some network participants. Service replication is employed as an approach to overcome this problem and to ensure higher service availability. Several protocols and algorithms for service replication in MANETs have been proposed. Most of these approaches apply topological analysis (like partitioning prediction) schemes to produce the required replication decisions. One approach, SDP, the Service Distribution Protocol, bases its decisions on analyzing interest in the service, an application layer concept. In this paper, we compare the performance of approaches based on these two criteria. First, we analyze protocols based on topology prediction and choose two typical representatives of this category, namely PSRP and SSRP. We then compare SDP as the only candidate using service interest to these two approaches. This comparison is based on an extensive set of simulation runs which are discussed in detail in the paper.Item Providing Reliability for Transactional Mobile Agents(Springer Berlin Heidelberg, 2013) Zeghache, Linda; Hurfin, Michel; Moise, Izabela; Badache, NadjibA transactional agent is a mobile agent that migrates from a site to another one in order to execute a distributed transaction assigned by a user. Works on transactional mobile agents have identified two problems that can not be solved by the agent alone. The first one is related to the reliability. The lack of a fault tolerant infrastructure and methodologies that address fault tolerant execution of mobile agents highlights a major drawback of this technology. The second problem for which the agent needs assistance is related to the atomic validation of the transaction. In this paper we address the mobile agent fault tolerance and the transactional support.