Publications Scientifiques

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    Enhanced UAVs mobility models for surveillance and intruders detection missions
    (Springer, 2022) Boutalbi, Mohammed Chaker; Riahla, Mohamed Amine; Ahriche, Aimad
    The use of chaotic solutions in designing UAVs’ (Unmanned Aerial Vehicles) mobility models for surveillance systems is becoming the trend in the last years. The substitution of the random part by a chaotic solution of a dynamic system has proven to be more effective. Therefore, this paper presents CSC (Chaotic Squad Coordination), a novel implementation scheme of UAVs mobility models in surveillance and intruders detection missions. The CSC comes as a low-cost solution to make the UAVs swarm efficiently explore the area of interest and detect malicious intruders, all in a spontaneous manner using a chaotic solution without the need for energy-consuming approaches like the ACO algorithm or deterministic group flocking rules. The used strategy guards the swarm’s movement unpredictability and offers the possibility of implementing a scalable collision avoidance flight plan. In addition, we designed a hybrid chaotic mobility model that switches between two chaotic attractors (Rossler and Ma systems). We used an iterative evolutionary algorithm to optimize its parameters in order to improve the overall delivered quality of service. Extensive simulation experiments are provided in this work to compare seven UAVs chaotic mobility models. The results confirmed the superiority of the CSC strategy that produced better quality of service concerning the swarm’s connectivity, the area coverage, and intruders detection, where the designed mobility model provides an overall reasonable trade-off in parallel with its higher area coverage fairness compared with its peers (CSC-based mobility models)
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    Cancellous bone structure assessment using a new trabecular connectivity
    (Elsevier, 2021) Harrar, Khaled
    Osteoporosis is a major public health problem; it is characterized by a loss in bone connectivity, which leads to a higher risk of fracture. The objective of this article is to develop a new connectivity parameter for bone microarchitecture characterization and osteoporosis assessment. The purpose is to discriminate 164 subjects composed of 82 healthy patients (HL) and 82 osteoporotic cases (OP). The new connectivity parameter involves several new topological features. The proposed method was compared to a traditional connectivity index, and the results reveal the superiority and the outperformance of the new parameter to discriminate the two groups of subjects with an accuracy (Acc) of 71.95 % and area under curve (AUC) of 80.03 %. Moreover, clinical parameters from patients were involved in this study, and five configurations were constructed, tested, and validated on the data using the k-fold cross-validation (CV) model with several values of k. Furthermore, support vector machine (SVM) was used and various kernels (i.e., linear, quadratic, cubic, and RBF functions) were tested in this study. The objective is to look for the configuration providing the best performance in terms of separation between the two populations. Furthermore, several classifiers (logistic regression, k-nearest neighbors, boosted trees, and naïve Bayes) were tested and a combination of these classifiers was carried out using the stacking ensemble technique to improve the accuracy of the final prediction. Moreover, several studies of state-of-the-art were compared to the proposed method. The results obtained reveal that the 10-fold CV approach combining the new trabecular connectivity index and RBF function of SVM achieved the highest accuracy with Acc = 88.41 %, and AUC = 95.24 %. In addition, the proposed ensemble Meta classifier improved the accuracy of SVM and achieved a high rate with Acc = 95.12 % and AUC = 98.40 % outperforming the existing methods in the literature
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    Gabriel graph-based connectivity and density for internal validity of clustering
    (Springer link, 2020) Boudane, Fatima; Berrichi, A.
    Clustering has an important role in data mining field. However, there is a large variety of clustering algorithms and each could generate quite different results depending on input parameters. In the research literature, several cluster validity indices have been proposed to evaluate clustering results and find the partition that best fits the input dataset. However, these validity indices may fail to achieve satisfactory results, especially in case of clusters with arbitrary shapes. In this paper, we propose a new cluster validity index for density-based, arbitrarily shaped clusters. Our new index is based on the density and connectivity relations extracted among the data points, based on the proximity graph, Gabriel graph. The incorporation of the connectivity and density relations allows achieving the best clustering results in the case of clusters with any shape, size or density. The experimental results on synthetic and real datasets, using the well-known neighborhood-based clustering (NBC) algorithm and the DBSCAN (density-based spatial clustering of applications with noise) algorithm, illustrate the superiority of the proposed index over some classical and recent indices and show its effectiveness for the evaluation of clustering algorithms and the selection of their appropriate parameters
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    Upper bounds for the forwarding indices of communication networks
    (Discrete Mathematics, 2004) El Haddad, M.; Manoussakis, Y.; Saad, R.
    The decision version of the forwarding index problem is, given a connected graph G and an integer ξ, to find a way of connecting each ordered pair of vertices by a path so that every vertex is an internal point of at most such paths. The optimization version of the problem is to find the smallest ξ for which a routing of this kind exists. Such a problem arises in the design of communication networks and distributed architectures. A model of parallel computation is represented by a network of processors, or machines processing and forwarding (synchronous) messages to each other, subject to physical constraints bearing on either the number of messages that can be processed by a single machine or the number of messages that can be sent through a connection. It was in this context that the problem was first introduced by Chung et al. (IEEE Trans. Inform. Theory 33 (1987) 224). The aim of this paper is to establish upper bounds for the optimal ξ as a function of the connectivity of the graph. © 2004 Published by Elsevier B.V
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    Properties of a hydrophone produced with porous PZT ceramic
    (2007) Boumchedda, K.; Hamadi, M.; Fantozzi, G.
    Interconnected piezoelectric porous ceramics PZT have been tested for possible use in hydrophone applications. These materials consisted of: (1) ceramics with fine porosity having pores from 50 to 100 μm and (2) cellular ceramics having cavities of the order of the millimeters. Porous ceramics are coated with flexible polymer standard polyurethane for the hydrostatics tests. The effect of the size of the pores and porous volume on the sensitivity of the sensor is studied and the performances of the hydrophones devices are presented