Institute Of La Francophonie Pour Linformatique Ifi

Hanoi, Vietnam

Institute Of La Francophonie Pour Linformatique Ifi

Hanoi, Vietnam

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Van Nam N.,French Institute for Research in Computer Science and Automation | Guerin-Lassous I.,French Institute for Research in Computer Science and Automation | Moraru V.,Institute Of La Francophonie Pour Linformatique Ifi | Sarr C.,University Of Thies
MSWiM'11 - Proceedings of the 14th ACM International Conference on Modeling, Analysis, and Simulation of Wireless and Mobile Systems | Year: 2011

Estimating the available bandwidth in IEEE 802.11-based multihop wireless networks is a very difficult task due to the medium sharing among contending nodes and collisions between hidden stations. Several methods have been proposed so far for these networks to compute the available bandwidth on wireless links. If some recent solutions such as ABE and IAB now take into account collisions and their impact on the mean backoff, none considers the packet retransmissions due to collisions although these retransmissions have an impact on the available bandwidth. In this article, we propose a new available bandwidth estimation for multihop wireless networks called RABE (Retransmission-based Available Bandwidth). This method integrates the average number of retransmission attempts in the available bandwidth estimation. RABE is evaluated by simulation and the obtained results show that RABE can achieve a mean error ratio of 17% in comparison with the real measurement. Furthermore RABE is at least two times more accurate than ABE and ten times more accurate than IAB. Copyright 2011 ACM.


Vu Q.-A.N.,Institute Of La Francophonie Pour Linformatique Ifi | Gaudou B.,CNRS Toulouse Institute in Information Technology | Canal R.,Institute Of La Francophonie Pour Linformatique Ifi | Hassas S.,University Claude Bernard Lyon 1 | Armetta F.,University Claude Bernard Lyon 1
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

In a distributed spatialized information collecting system managed by a swarm of agents, where some are supposed disturbed, the maintenance of the system coherence and cooperation between reliable elements is a challenge. This paper tackles the problem of finding an efficient mechanism to ensure the coherence of the system and to optimize system performance. The main contribution of this paper consists of two major steps: (i) use trust-based mechanism to ensure the coherence and the robustness of the system; (ii) allow reliable elements to create dynamic clusters based on trust. We propose two different organizations in order to manage these issues and show how they must interact: a social one in which each agent maintains a TrustSet to estimate trust on others; a spacial one in which reliable elements are grouped in an "ad hoc type" network to improve cooperation between themselves. © Springer-Verlag Berlin Heidelberg 2012.


Taillandier P.,Institute Of La Francophonie Pour Linformatique Ifi | Taillandier P.,Institute Geographique National IGN | Duchene C.,Institute Geographique National IGN | Drogoul A.,Institute Of La Francophonie Pour Linformatique Ifi | Drogoul A.,University Pierre and Marie Curie
International Journal of Geographical Information Science | Year: 2011

Automating the generalisation process, a major issue for national mapping agencies, is extremely complex. Several works have proposed to deal with this complexity using a trial and error strategy. The performance of systems based on such a strategy is directly dependent on the quality of the control knowledge (i.e. heuristics) used to guide the trials. Unfortunately, most of the time, the definition and updation of knowledge is a fastidious task. In this context, automatic knowledge revision can not only improve the performance of the generalisation, but also allow it to automatically adapt to various usages and evolve when new elements are introduced. In this article, an offline knowledge revision approach is proposed, based on a logging of the system and on the analysis of outcoming logs. This approach is dedicated to the revision of control knowledge expressed by production rules. We have implemented and tested this approach for the automated generalisation of groups of buildings within a generalisation model called AGENT, from initial data that reference a scale of approximately 1:15,000 compared with the target map's scale of 1:50,000. The results show that our approach improves the quality of the control knowledge and thus the performance of the system. Moreover, the approach proposed is generic and can be applied to other systems based on a trial and error strategy, dedicated to generalisation or not. © 2011 Copyright Taylor and Francis Group, LLC.


Nguyen T.K.,Institute Of La Francophonie Pour Linformatique Ifi | Marilleau N.,Institute Of Recherche Pour Le Developpment Ird | Ho T.V.,Institute Of La Francophonie Pour Linformatique Ifi | El Fallah A.,University Pierre and Marie Curie
ACM International Conference Proceeding Series | Year: 2013

Major researches in the domain of complex systems are interdisciplinary, collaborative/participative and geographically distributed. Therefore, the simulation of complex systems is usually a collaborative/participative work that highly demands the exchange, from distance, of participants. However, most of the actual simulators cannot support this exchange. In this paper, we will present a new method to create a participatory simulator supporting the collaboration/participation from distance in the complex system participatory simulation. The method includes: (i) a collaborative software infrastructure, named PAMS, containing common collaborative tools (videoconferencing, instant messaging, and many other communication tools) and specific tools dedicated to the simulation domain (sharing experiments, results, experience exchange and various type of manipulation tools) and (ii) a role-based meta-model facilitating the integration of actual simulators into PAMS. Copyright © 2013 ACM.


Van Minh L.,Hanoi University | Adam C.,RMIT University | Canal R.,Institute Of La Francophonie Pour Linformatique Ifi | Gaudou B.,Toulouse 1 University Capitole | And 3 more authors.
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

Nowadays, more and more emergency evacuation simulations are used to evaluate the safety level of a building during an emergency evacuation after an accident. The heart of this kind of simulations is the simulation of human behavior because simulation results depend for a big part on how this behavior is simulated. However, human behaviors in a real emergency situation are determined by a lot of cognitive mechanisms. In order to make the simulation more realistic, plenty of factors (e.g. innate characteristics, perception of the environment, internal rules, personality and even emotions) that affect human behaviors must be taken into account. This paper focuses on the influence of emotions, and more precisely on the influence of their dynamics and propagation from an agent to another. The main contribution of this work is the development of a model of emotions taking into account their dynamics and their propagation and its integration in an evacuation simulation. The first results of the simulation show the benefits of considering emotion propagation. © Springer-Verlag Berlin Heidelberg 2012.


Nguyen M.H.,Post and Telecommunication Institute of Technology | Tran D.Q.,Institute Of La Francophonie Pour Linformatique Ifi
International Journal of Innovative Computing, Information and Control | Year: 2013

Trust plays a crucial role in supporting agents to select the partners while interacting with each other in open distributed multi-agent systems. Researches on computational trust mostly focus on considering three types of trust: individual experience, inference trust from other agents in the community, and hybrid trust. Most current hybrid trust models are the combination of experience and inference trusts and make use of some propagation mechanism to enable agents to share his/her final trust with partners. However, the disadvantage of these models is that their use of such mechanism could result in high cost in computation. The problem with such a propagation based sharing may be reduced to the issue of considering which type of trusts an agent should utilize in evaluating partners and which type of trusts should be shared among agents. In this paper, we first propose a computational trust model which is a combination of experience and reference trusts. Our model may enable agents to evaluate the degree of trust on their partners, which is computed with a weighted combination based on the linguistic quantifier function of their own experiences and the trustworthiness on their partners in the agent society. Then, we investigate which types of trust should be shared among agents and how they affect the effectiveness of interaction in our model. Our experiments are performed in an e-commerce environment and the experimental results have demonstrated that: (i) Changing two internal parameters, which are the linguistic quantifier functions and weight vectors for aggregating the experience and reference trusts, may contribute to selecting the best partner for an agent but not much; (ii) combining the experience and inference trusts is better than using the single experience trust for estimating the trustworthiness of a partner; (iii) agents may share their single experience trust or combination trust with their partners and furthermore their making use of any of these sharing strategies may not affect the evaluation of product quality. © 2013 ICIC International.


Pham Q.-D.,Catholic University of Leuven | Do P.-T.,Hanoi University of Science and Technology | Deville Y.,Catholic University of Leuven | Ho T.-V.,Institute Of La Francophonie Pour Linformatique Ifi
ACM International Conference Proceeding Series | Year: 2010

Routing problems have been considered as central problems in the fields of transportation, distribution and logistics. LS(Graph) is a generic framework allowing to model and solve constrained optimum paths problems on graphs by local search where paths are known to be elementary (i.e., edges, vertices cannot be repeated on paths). In many real-world situations, the paths to be determined are not known to be neither simple nor elementary. In this paper, we extend the LS(Graph) framework by designing and implementing abstractions that allow to model and solve constrained paths problem where edges, vertices can be repeated on paths (call non-simple paths). We also propose an instance of such problem class: the routing for network covering (RNC) problem which arises in the context of rescue after a natural disaster in which we have to route a fleet of identical vehicles with limited capacity on a transportation network in order to collect the informations of the disaster. Given an undirected weighted graph G = (V, E) representing a transportation network and a vertex v 0 ε V representing the depot, the RNC problem consists of routing a fleet of unlimited number of identical vehicles with limited capacity that cannot perform a path of length > L such that each vehicle starts from and teminates at the depot and all the edges of a given set S (S ⊆ E) must be visited. The objective of the routing plan is to minimize the number of vehicles used. This paper discusses the challenge around this problem and applies the constructed framework to the resolution of this problem. The proposed model is generic; it allows to solve some variants of the problem where side constraints are required to be added. © 2010 ACM.


Bui Q.T.,Institute Of La Francophonie Pour Linformatique Ifi | Pham Q.-D.,Catholic University of Leuven | Deville Y.,Catholic University of Leuven
ACM International Conference Proceeding Series | Year: 2011

Partitioning a field into parcels is one step of the project of merging and repartitioning agricultural lands which emerges in many provinces in Vietnam. Historically, this problem has been conducted based on human experiences and without using optimization technology nor computer science. In this paper, we propose a model for the problem of fields partitioning taking into account real issues. We also propose local search algorithms for solving this problem with typical shapes of fields i.e., rectangle, trapezium, triangle. Experimental results show that our local search approach gives better solutions than those realized by human experiences. © 2011 ACM.


Grignard A.,Institute Of La Francophonie Pour Linformatique Ifi | Drogoul A.,Institute Of La Francophonie Pour Linformatique Ifi | Zucker J.-D.,Institute Of La Francophonie Pour Linformatique Ifi
Proceedings - 2013 RIVF International Conference on Computing and Communication Technologies: Research, Innovation, and Vision for Future, RIVF 2013 | Year: 2013

Agent-based Modeling is playing a key role in an increasing number of approaches addressing modeling complex systems. Historically, such models were focused on describing the system modelled dynamics but not the interaction or visualization of the model itself. The new requirements for high-level realistic visualization and online analysis tools of ABM simulations raise key issues that are yet unsolved: how to visualize interaction between entities and more generally abstracting the key information from the system dynamics. Instead of ad-hoc existing approaches that require reification in the model, we propose an approach dedicated to visualize and discover emerging dynamics from the model. In this approach, the execution of the simulation and its representation is separated and building a visualization is like building a visualization model on top of the reference model. The techniques presented here have been implemented in an Agent-based simulation platform, Gama, and illustrate the new perspective on visualization in Agent-based Modeling. © 2013 IEEE.


Nguyen M.H.,Institute Of La Francophonie Pour Linformatique Ifi | Ho T.V.,Institute Of La Francophonie Pour Linformatique Ifi | Nguyen T.N.A.,Institute Of La Francophonie Pour Linformatique Ifi | Zucker J.-D.,Institute Of La Francophonie Pour Linformatique Ifi
2012 IEEE RIVF International Conference on Computing and Communication Technologies, Research, Innovation, and Vision for the Future, RIVF 2012 | Year: 2012

A problem arises in many fire evacuations, especially in a public site like a supermarket: what is better, following the one's own path, following the crowd, or following the evacuation signs which indicate the evacuation direction? This paper presents a model and simulations of these three behaviors in the realistic environment of the Metro supermarket of Hanoi. The simulations indicate that in case of a fire evacuation of the Metro supermarket of Hanoi: the average time to escape in case of following the evacuation signs is shorter and the power lost is lower than following the own path or following the crowd. Additionally, in the general view, following the evacuation signs got higher the % of survivals and lower the % of death than following the one's own path or following the crowd. ©2012 IEEE.

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