Browsing by Author "Nouali-Taboudjemat, Nadia"

Now showing 1 - 20 of 58
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    A critical review of quality of service models in mobile ad hoc networks
    (Inderscience Enterprises Ltd, 2019) Bouchama, Nadir; Aïssani, Djamil; Djellab, Natalia; Nouali-Taboudjemat, Nadia
    Quality of service (QoS) provisioning in mobile ad hoc networks (MANETs) consists of providing a complex functionality in a harsh environment where resources are scarce. Thus, it is very challenging to build an efficient solution to address this issue. The proposed solutions in the literature are broadly classified into four categories, namely: QoS routing protocols, QoS signalling, QoS-aware MAC protocols and QoS models, which are the main concern of our study. The contribution of this paper is threefold: Firstly, we propose a set of guidelines to deal with the challenges facing QoS models design in ad hoc networks. Secondly, we propose a new taxonomy for QoS models in ad hoc networks. Finally, we provide an in-depth survey and discussion of the most relevant proposed frameworks.
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    A policy-based context-aware approach for the commitment of mobile transactions
    (ACM, 2008) Nouali-Taboudjemat, Nadia; Drias, Habiba
    The transaction paradigm ensures consistency in the presence of concurrent accesses to shared data and in the presence of failures. Traditionally, the transaction semantics is defined by the ACID properties (Atomicity, Consistency, Isolation and Durability) which implementation is through such mechanisms as commitment protocols ensuring Atomicity and concurrency control protocols ensuring Isolation. Many transactional models were developed to support the diverse and variable applications needs, and more recently to overcome the constraints induced by the evolution of distributed systems environments toward wireless and mobile. Indeed, the latter are characterized by limitations in computing resources, communications and energy as well as dynamic variations in terms of resource availability and configuration. In this paper, our contribution is mainly focused on the problem of atomic commitment. We adopted an approach based on the context-aware adaptation for the management of mobile transactions. We therefore present the commit protocol aTCP (Adaptable Transaction Commit Protocol) which allows for adaptation to the requirements of applications and mobile context in terms of transactional properties and execution cost. For the implementation of aTCP we offer a context-aware architecture based on policies.
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    A Survey on Distributed Graph Pattern Matching in Massive Graphs
    (ACM, 2021-02) Bouhenni, Sarra; Yahiaoui, Saïd; Nouali-Taboudjemat, Nadia; Kheddouci, Hamamache
    Besides its NP-completeness, the strict constraints of subgraph isomorphism are making it impractical for graph pattern matching (GPM) in the context of big data. As a result, relaxed GPM models have emerged as they yield interesting results in a polynomial time. However, massive graphs generated by mostly social networks require a distributed storing and processing of the data over multiple machines, thus, requiring GPM to be revised by adopting new paradigms of big graphs processing, e.g., Think-Like-A-Vertex and its derivatives. This article discusses and proposes a classification of distributed GPM approaches with a narrow focus on the relaxed models.
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    A two-phase commit protocol for mobile wireless environment
    (ACM, 2005) Nouali-Taboudjemat, Nadia; Doucet, Anne; Drias, Habiba
    The challenges of wireless and mobile computing environments have attracted the attention of researchers to revisit the conventional implementation of distributed computing paradigms. In this paper we propose to revisit the conventional implementation of the Two Phase Commit (2PC) protocol which is a fundamental asset of transactional technology for ensuring the consistent commitment of distributed transactions. We propose a new execution framework providing an efficient extension that is aware of the mobility. The proposed M2PC (Mobile 2PC) protocol preserves the 2PC principle and the freedom of the mobile clients and servers while it minimizes the impact of unreliable wireless communications.
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    AdSIP: Decentralized SIP for Mobile Ad Hoc Networks
    (IEEE, 2012-03) Yahiaoui, Saïd; Belhoul, Yacine; Nouali-Taboudjemat, Nadia; Kheddouci, Hamamache
    SIP signaling protocol relies on centralized SIP servers deployed on the infrastructure of the network to route SIP messages in order to enable user endpoints to discover each other. However, the lack of the infrastructure in ad hoc networks requires that the network nodes support the tasks of participants discovery and SIP messages routing. In this paper, we propose AdSIP protocol which is a completely distributed architecture for SIP that implements SIP servers in selected nodes. The SIP servers are selected using a distributed algorithm constructing a connected minimal global offensive alliance. AdSIP is implemented and compared under NS-2 with TCA protocol which uses a cluster based approach. The simulation results show the advantages of AdSIP and confirm that it is adapted to mobile ad hoc networks by giving low session establishment time, low control overhead and high service availability.
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    AdSIP: Decentralized SIP for Mobile Ad hoc Networks
    (CERIST, 2011-12) Nouali-Taboudjemat, Nadia; Belhoul, Yacine; Yahiaoui, Saïd
    SIP (Session Initiation Protocol) is an IETF signaling protocol designed to create, modify and terminate sessions between two or many users in multimedia applications. The implementation of SIP needs the use of proxy servers which are centralized entities to route SIP requests and responses to enable user endpoints to discover each other. However, the infrastructureless of ad hoc networks requires that the network nodes support the tasks of participants’ discovery and SIP routing messages. In this paper, we propose the AdSIP protocol which is a completely distributed architecture for SIP that implements the proxy servers in selected nodes. The proxy servers are selected using a distributed algorithm constructing a connected minimal global offensive alliance. AdSIP is implemented and compared under NS-2 with another protocol which uses a cluster based approach. The simulation results show the advantages of AdSIP and demonstrate that it is adapted to mobile ad hoc networks by giving low session establishment time, low control overhead and high service availability.
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    Les Algorithmes génétiques Application à la segmentation des images
    (CERIST, Alger, 2004) Lassouaoui, Nadia; Hamami, Latifa; Nouali-Taboudjemat, Nadia
    Les algorithmes génétiques ont des propriétés qui en font des candidats de choix pour résoudre des problèmes d’optimisation dans lesquels la taille de l’espace de recherche est importante, où les paramètres interagissent de manière complexe et où très peu d’informations sur la fonction à optimiser sont disponibles. Ces propriétés ont motivé leur application à divers domaines. Dans ce papier, nous présentons les fondements des AGs ; les travaux récents effectués en analyse d’images et plus particulièrement en segmentation ; nous étudions en détails et appliquons un algorithme non supervisé de segmentation, nous l’améliorons en proposant un nouvel opérateur de mutation. Et avec le multiseuillage par Fisher, nous l’avons adapté à la détection des corps cellulaires dans des images de cellules biologiques du col.
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    An Efficient Measure for Evaluating Association Rules
    (CERIST, 2014-06-24) Djenouri, Youcef; Gheraibai, Youcef; Mehdi, Malika; Bendjoudi, Ahcène; Nouali-Taboudjemat, Nadia
    Association rules mining (ARM) has attracted a lot of attention in the last decade. It aims to extract a set of relevant rules from a given database. In order to evaluate the quality of the resulting rules, existing measures, such as support and confidence, allow to evaluate the resulted rules of ARM process separately, missing the different dependencies between the rules. This paper addresses the problem of evaluating rules by taking into account two aspects : (1) The accuracy of the returned rules on the input data and (2) the distance between the returned rules. The rules set that covers the maximum of rules space is considered. To analyze the behavior of the proposed measure, it has been tested on two recent ARM algorithms BSO-ARM and HBSO-TS.
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    Association rules mining using evolutionary algorithms
    (LNCS, 2014-10-16) Djenouri, Youcef; Bendjoudi, Ahcène; Nouali-Taboudjemat, Nadia
    This paper deals with association rules mining using evolutionary algorithms. All previous bio-inspired based association rules mining approaches generate non admissible rules which the end-user can not exploit them. In this paper, we propose two approaches permit to avoid non admissible rules by developing new strategy called delete and decomposition strategy. If an item is appeared in the antecedent and the consequent parts of given rule, this rule is composed on two admissible rules. Then, we delete such item to the antecedent part of the first rule and we delete the same item to the consequent part of the second rule. We also proposed two approaches (IARMGA and IARMMA), the first approach uses a classical genetic algorithm in the search process. However, the second one employs a mimetic algorithm to improve the quality of returned rules. To demonstrate the suggested approaches, several experiments have been carried out using both synthetic and reals instances. The results reveal that it has a compromise between the execution time and the quality of output rules. Indeed, IARMGA is faster than IARMMA whereas the last one outperforms IARMGA in terms of rules quality.
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    Association rules mining using evolutionary algorithms 
    (CERIST, 2014-10-16) Djenouri, Youcef; Bendjoudi, Ahcène; Nouali-Taboudjemat, Nadia
    This paper deals with association rules mining using evolutionary algorithms. All previous bio-inspired based association rules mining approaches generate non admissible rules which the end-user can not exploit them. In this paper, we propose two approaches permit to avoid non admissible rules by developing new strategy called delete and decomposition strategy. If an item is appeared in the antecedent and the consequent parts of given rule, this rule is composed on two admissible rules. Then, we delete such item to the antecedent part of the first rule and we delete the same item to the consequent part of the second rule. We also proposed two approaches (IARMGA and IARMMA), the first approach uses a classical genetic algorithm in the search process. However, the second one employs a mimetic algorithm to improve the quality of returned rules. To demonstrate the suggested approaches, several experiments have been carried out using both synthetic and reals instances. The results reveal that it has a compromise between the execution time and the quality of output rules. Indeed, IARMGA is faster than IARMMA whereas the last one outperforms IARMGA in terms of rules quality.
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    Authentification dans les réseaux sans-fils
    (Centre de Recherce sur l'Information Scientifique et Technique, 2009) Amira, Abdelouahab; Hadj arab, Samir; Nouali-Taboudjemat, Nadia
    L'authenti cation est l'un des premier rempart de la s ecurit e informatique, son but est de v eri er l'identit e dont une entit e (personne ou machine) se r eclame. Les r eseaux sans fils sont de par leur nature moins sur que les r éseaux cabl es : comme l'information est transmise dans l'air sous forme d'ondes radios elle est susceptible d'etre captur ée, alt er ée, etc. Pour les r éseaux WiFi sur lesquels nous avons travaillé , plusieurs solutions ont ét é propos ées pour les s écuriser. Parmi elles, on trouve les protocoles WEP, WPA, WPA2 et 802.1X. N éanmoins, certaines de ces solutions se sont r év él ées inaptes à assurer un niveau de s ecurit e satisfaisant. Dans ce m émoire nous avons r éalis é une synthèse sur l'authentifi cation dans les r éseaux sans fils, puis quelques tests avant de proposer une architecture sans fil s écuris ée assurant l'authentifi cation en se basant sur un serveur d’authentification RADIUS.
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    CBBC : chaining block before ciphering : chainage des blocs avant chiffrement
    (CERIST, Alger, 2003) Nouali-Taboudjemat, Nadia; Nouali, Omar; Berbar, A.; Saadi, R.
    L’échange de données ou d’information sur Internet (informations privées ou personnelles, transactions commerciales, etc.) est l’un des services le plus populaire et le plus exposé aux attaques d’origine malfaisante, d’où l’importance de la sécurité d’un tel service. La sécurité concerne la confidentialité, l’intégrité, l’authentification, et la non-répudiation. La cryptographie est considéré actuellement comme étant le mécanisme de base pour la sécurité sur Internet. Cet article s’intéresse à la protection des échanges contre les attaques qui peuvent se produire durant leur transmission sur le réseau. La technique de chiffrement est utilisé ici comme moyen pour offrir à l’utilisateur la possibilité de choisir un, parmi trois niveaux de sécurité selon ses besoins ou ceux de son application (basse, moyenne et haute sécurité). Mais la contribution la plus importante de cet article est d’avoir renforcé les techniques de chiffrement utilisées en introduisant deux nouveaux modes de chaînage que nous avons associés à l’utilisation, à la fois, de deux algorithmes de chiffrement au lieu d’un.
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    Cerist News
    (2011-03) CERIST; Nouali-Taboudjemat, Nadia
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    Data reordering for minimizing threads divergence in GPU-based evaluating association rules
    (CERIST, 2015-03-26) Djenouri, Youcef; Bendjoudi, Ahcène; Mehdi, Malika; Habbas, Zineb; Nouali-Taboudjemat, Nadia
    This last decade, the success of Graphics Processor Units (GPUs) has led researchers to launch a lot of works on solving large complex problems by using these cheap and powerful architecture. Association Rules Mining (ARM) is one of these hard problems requiring a lot of computational resources. Due to the exponential increase of data bases size, existing algorithms for ARM problem become more and more inefficient. Thus, research has been focusing on parallelizing these algorithms. Recently, GPUs are starting to be used to this task. However, their major drawback is the threads divergence problem. To deal with this issue, we propose in this paper an intelligent strategy called Transactions- based Reordering "TR" allowing an efficient evaluation of association rules on GPU by minimizing threads divergence. This strategy is based on data base re-organization. To validate our proposition, theoretical and experimental studies have been carried out using well-known synthetic data sets. The results are very promising in terms of minimizing the number of threads divergence.
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    Data reordering for minimizing threads divergence in GPU-based evaluating association rules
    (2015-06) Djenouri, Youcef; Bendjoudi, Ahcène; Mehdi, Malika; Habbas, Zineb; Nouali-Taboudjemat, Nadia
    This last decade, the success of Graphics Processor Units (GPUs) has led researchers to launch a lot of works on solving large complex problems by using these cheap and powerful architecture. Association Rules Mining (ARM) is one of these hard problems requiring a lot of computational resources. Due to the exponential increase of data bases size, existing algorithms for ARM problem become more and more inefficient.Thus, research has been focusing on parallelizing these algorithms. Recently, GPUs are starting to be used to this task. However, their major drawback is the threads divergence problem. To deal with this issue, we propose in this paper an intelligent strategy called transactions-based Reordering ”TR” allowing an efficient evaluation of association rules on GPU by minimizing threads divergence. This strategy is based on data base re-organization. To validate our proposition, theoretical and experimental studies have been carried out using well-known synthetic datasets. The results are very promising in terms of minimizing the number of threads divergence.
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    Detection and Description the Lesions in Brain Images
    (University Cadi Ayyad (Marroc), 2005-11) Lassouaoui, Nadia; Hamami, Latifa; Nouali-Taboudjemat, Nadia; Hadjar, Samir; Saadi, Hocine
    In this paper, we present the various stages for lesion recognition in brain images. We firstly apply a filtering based on geodesic reconstruction operator for increasing the quality of image. After, we use an unsupervised segmentation genetic algorithm for detecting the abnormal zones with respect of theirs morphological characteristics because they define the nature of illness (cyst, tumour, malignant, benign, …). The obtained segmented images are analyzed for computing the characteristics of illness which are necessary for the recognition stage for deducing a decision about the type of illness. So, we give also the various algorithms used for computing the morphological characteristics of lesions (size, shape, position, texture, …). Since we obtain a decision about the malignity or benignity of the lesion and a quantitative information for helping the doctors to locate the sick part.
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    Disaster Management Projects using Wireless Sensor Networks
    (Barolli et al., 2014-05-13) Benkhelifa, Imane; Nouali-Taboudjemat, Nadia; Moussaoui, Samira
    There are numerous projects dealing with disaster management and emergency response that use wireless sensor networks technologies. Indeed, WSNs offer a good alternative compared to traditional ad hoc networks. Air pollution monitoring, forest fire detection, landslide detection, natural disaster prevention, industrial sense and control applications, dangerous gas leakage, water level monitoring, vibration detection to prevent an earthquake, radiation monitoring are examples of the WSN applications related to disaster management. This paper presents an overview of the recent projects using WSN to collect data in disaster areas.
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    Disaster Management Projects using Wireless Sensor Networks: An Overview
    (CERIST, 2014-02) Benkhelifa, Imane; Nouali-Taboudjemat, Nadia
    There are numerous projects dealing with disaster management and emergency response that use wireless sensor networks technologies. Indeed, WSNs offer a good alternative compared to traditional ad hoc networks. Air pollution monitoring, forest fire detection, landslide detection, natural disaster prevention, industrial sense and control applications, dangerous gas leakage, water level monitoring, vibration detection to prevent an earthquake, radiation monitoring are examples of the WSN applications related to disaster management. This paper presents an overview of the recent projects using WSN to collect data in disaster areas.
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    Distributed graph pattern matching via bounded dual simulation
    (Elsevier, 2022-09) Bouhenni, Sarra; Yahiaoui, Saïd; Nouali-Taboudjemat, Nadia; Kheddouci, Hamamache
    Graph Pattern Matching (GPM) finds subgraphs of a large data graph that are similar to an input query graph. It has many applications, such as pattern recognition, detecting plagiarism, and finding communities in social networks. Current real-world applications generate massive amounts of data that cannot be stored on the memory of a single machine, which raises the need for distributed storage and processing. Recent relaxed GPM models, although of polynomial time complexity, are nevertheless not distributed by nature. Moreover, the existing relaxed GPM algorithms are limited in terms of scalability. In this paper, we propose Bounded Dual Simulation (BDSim) as a new relaxed model for a scalable evaluation of GPM in massive graphs. BDSim captures more semantic similarities compared to graph simulation, dual simulation, and even strong simulation. It preserves the vertices’ proximity by eliminating cycles of unbounded length from the resulting match graph. Furthermore, we propose distributed vertex-centric algorithms to evaluate BDSim. We prove their effectiveness and efficiency through detailed theoretical validation and extensive experiments conducted on real-world and synthetic datasets. To the best of our knowledge, BDSim is the first relaxed GPM model that captures the cyclic structure of the query graph while being feasible in cubic time.
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    Efficient parallel edge-centric approach for relaxed graph pattern matching
    (Springer, 2022-02) Bouhenni, Sarra; Yahiaoui, Saïd; Nouali-Taboudjemat, Nadia
    Prior algorithms on graph simulation for distributed graphs are not scalable enough as they exhibit heavy message passing. Moreover, they are dependent on the graph partitioning quality that can be a bottleneck due to the natural skew present in real-world data. As a result, their degree of parallelism becomes limited. In this paper, we propose an efficient parallel edge-centric approach for distributed graph pattern matching. We design a novel distributed data structure called ST that allows a fine-grain parallelism, and hence guarantees linear scalability. Based on ST, we develop a parallel graph simulation algorithm called PGSim. Furthermore, we propose PDSim, an edge-centric algorithm that efficiently evaluates dual simulation in parallel. PDSim combines ST and PGSim in a Split-and-Combine approach to accelerate the computation stages. We prove the effectiveness and efficiency of these propositions through theoretical guarantees and extensive experiments on massive graphs. The achieved results confirm that our approach outperforms existing algorithms by more than an order of magnitude.