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Search Results: 1 - 10 of 149776 matches for " H Bentaleb "
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Survey of Clustering Schemes in Mobile Ad hoc Networks  [PDF]
Abdelhak Bentaleb, Abdelhak Boubetra, Saad Harous
Communications and Network (CN) , 2013, DOI: 10.4236/cn.2013.52B002
Abstract: Mobile ad-hoc networks (MANETs) are a specific kind of wireless networks that can be quickly deployed without pre- existing infrastructures. They are used in different contexts such as collaborative, medical, military or embedded applications. However, MANETs raise new challenges when they are used in large scale network that contain a large number of nodes. Subsequently, many clustering algorithms have emerged. In fact, these clustering algorithms allow the structuring of the network into groups of entities called clusters creating a hierarchical structure. Each cluster contains a particular node called cluster head elected as cluster head according to a specific metric or a combination of metrics such as identity, degree, mobility, weight, density, etc. MANETs has drawbacks due to both the characteristics of the transmission medium (transmission medium sharing, low bandwidth, etc.) and the routing protocols (information diffusion, path finding, etc.). Clustering in mobile ad hoc networks plays a vital role in improving resource management and network performance (routing delay, bandwidth consumption and throughput). In this paper, we present a study and analyze of some existing clustering approaches for MANETs that recently appeared in literature, which we classify as: Identifier Neighbor based clustering, Topology based clustering, Mobility based clustering, Energy based clustering, and Weight based clustering. We also include clustering definition, review existing clustering approaches, evaluate their performance and cost, discuss their advantages, disadvantages, features and suggest a best clustering approach.
Central African biomes and forest succession stages derived from modern pollen data and plant functional types
J. Lebamba, A. Ngomanda, A. Vincens, D. Jolly, , C. Favier, H. Elenga,I. Bentaleb
Climate of the Past (CP) & Discussions (CPD) , 2009,
Abstract: New detailed vegetation reconstructions are proposed in Atlantic Central Africa from a modern pollen data set derived from 199 sites (Cameroon, Gabon and Congo) including 131 new sites. In this study, the concept of plant functional classification is improved with new and more detailed plant functional types (PFTs) and new aggregations of pollen taxa. Using the biomisation method, we reconstructed (1) modern potential biomes and (2) potential succession stages of forest regeneration, a new approach in Atlantic Central African vegetation dynamics and ecosystem functioning reconstruction. When compared to local vegetation, potential biomes are correctly reconstructed (97.5% of the sites) and tropical rain forest (TRFO biome) is well identified from tropical seasonal forest (TSFO biome). When the potential biomes are superimposed on the White's vegetation map, only 76.4% of the sites are correctly reconstructed. But using botanical data, correspondence and cluster analyses, the 43 sites from Congo (Mayombe) evidence more affinities with those of central Gabon and so they can also be considered as correctly reconstructed as TRFO biome and White's map should be revised. In terms of potential succession stages of forest regeneration, the mature forest (TMFO) is well differentiated from the secondary forest (TSFE), but inside this latter group, the young and the pioneer stages are not clearly identified due probably to their low sampling representation. Moreover, linked to their progressive and mosaic character, the boundaries between two forest biomes or two forest stages are not clearly detected and need also a more intensive sampling in such transitions.
Tumeur de Buschke-L wenstein: A Propos d\'un Cas avec Revue de La Litterature
A Elhams, H Bentaleb, T Karmouni, K Tazi, K Elkhader, A Koutani, A A Ibn Attya, M Hachimi
African Journal of Urology , 2007,
Abstract:
Abord trans-symphysaire des ruptures posttramatiques de l’urètre postérieur chez l’adulte
A Bensouda, H Bentaleb, J Reffad, T Karmouni, K Tazi, K Khader, A Koutani, A Andaloussi, M Hachimi
African Journal of Urology , 2009,
Abstract: Objectif: Etudier la place de la voie trans-symphysaire dans le traitement des ruptures posttraumatiques de l’urètre postérieur vues tardivement et en évaluer ses résultats. Patients et méthodes: Cinq malades ayant une rupture complète post-traumatique de l’urètre postérieur (> 2,5 cm et/ou échec d’un traitement antérieur) ont été traités dans notre service au stade de sténose urétrale. Tous les patients ont eu une urétrorraphie termino-terminale par voie trans-symphysaire seule. Une description technique et une évaluation clinique et paraclinique des résultats sur le plan mictionnel et sexuel ont été réalisées dans ce travail. Résultats: Les résultats ont été évalués avec un suivi médian de 19 mois. Aucune complication post-opératoire immédiate (saignement, fistule, douleur) n’a été rapportée. Sur le plan mictionnel, on a constaté dans tous les cas une miction satisfaisante, sans troubles de la continence et un cas de dysfonction érectile améliorée par le traitement médical. Aucun patient ne s’est plaint de troubles de la statique pelvienne. Conclusion: La voie trans-symphysaire constitue un excellent abord pour le traitement des lésions complexes de l’urètre postérieur vues tardivement. Cette technique permet d’avoir un abord direct sur l’urètre postérieur et de réaliser une suture termino-terminale sans tension. Les résultats sont satisfaisants et les inconvénients sont plus théoriques que réels. Mots clés : Rupture de l’urètre postérieur, sténose de l’urètre postérieur, urétrorraphie, voie transsymphysaire
Prise en charge des traumatismes iatrogènes de l\'uretère: A propos de 24 cas
H Bentaleb, A Bensouda, M Kabbaj, T Karmouni, K Tazi, K El Kader, A Koutani, A I Attya, M Hachimi
African Journal of Urology , 2007,
Abstract: Objectifs: Rapporter la prise en charge diagnostique et thérapeutique d\'une série de 24 traumatismes de l\'uretère. Patients et méthodes : Il s\'agit d\'une étude rétrospective. De juin 1993 à juin 2005, 24 patients (22 femmes et 2 hommes) ont été pris en charge pour un traumatisme de l\'uretère dans notre h pital. L\'age moyen était de 41 ans (extrêmes 22 et 65 ans). Résultats: Les traumatismes de l\'uretère étaient le plus souvent liés à une chirurgie gynécologique (22/24 cas, soit 92%). Le délai moyen du traumatisme de l\'uretère et le diagnostic a été de 5 mois avec une seule découverte per-opératoire (3,8%). Le traitement endo-urologique exclusif a été adopté chez 4 patients, l\'urétéroscopie avec anastomose termino-terminale dans 5 cas, et la chirurgie à ciel ouvert dans 15 cas. Une patiente a bénéficié d\'une urétérorraphie termino-terminale après échec du traitement endoscopique par sonde double J. Il n\'a eu aucune néphrectomie dans cette série. Le suivi moyen a été de 60 mois. Quatre patients ont été perdus de vue. Sur le plan clinique, la disparition des lombalgies a été notée dans tous les cas. Sur le plan radiologique, une persistance d\'une hypotonie urétéro-pyélocalicielle résiduelle a été notée dans 5 cas et un bon passage urétéral sans sténose dans les autres cas. Conclusion: Les traumatismes de l\'uretère sont le plus souvent iatrogènes et secondaires à une chirurgie gynécologique. Leur prise en charge est avant tout endo-urologique. La prévention de ce type de lésion passe notamment par la montée de sondes urétérales en préopératoire afin de mieux repérer les uretères au cours de la chirurgie. Objectives: To evaluate the diagnosis and treatment of 24 patients with ureteral injury at our institution. Patients and Methods: In this retrospective study we evaluated 24 patients (22 females and 2 males) with ureteral injury treated at our institution between June 1993 and June 2005. The average age was 41 years (range 22 - 65 years). Results: The majority of ureteral injuries occurred during gynecological surgery (22/24 cases =92%). The time elapsed between the ureteral injury and diagnosis was 5 months on average; only in one case (3.8%), the injury was discovered during surgery. Four patients were treated endoscopically, while ureteroscopy and end-to-end anastomosis was applied in 5 and open surgery in 15 cases. End-to-end ureterorraphy with placement of a double-J catheter was necessary in one patient, where endoscopic treatment had failed. After an average follow-up period of 60 months, loin pain had resolved in all cases. On radiological evaluation, a residual uretero-pyelocalyceal hypotony was noted in 5 cases and a satisfactory ureteral passage without strictures in the others. No nephrectomy was necessary in this series. Conclusion: Ureteral injury is most often secondary to gynecological surgery. In the majority of cases endourologic repair is the treatment of choice. It is recommended to pass ureteral catheters pre-operati
The P40 Cutting Tool Wear Modelization Machining Fk20MnCr5  [PDF]
Idriss Amara, Embarek Ferkous, Fay?al Bentaleb, Razika Aouad
Engineering (ENG) , 2011, DOI: 10.4236/eng.2011.39114
Abstract: This work presents an experimental study to describe a wear zone in the P40 cutting tools used during a dry lathing. Mechanics of cutting has been presented to investigate the effects of edge geometry of the cutting tool carbide cutting insert. In the field of the metals cutting, the wear of the cutting tools leads to a degradation of the cutting zone and work. It is thus important to study the evolution of the cutting criteria allowing to follow the tool degradation during a manufacturing operations and thus to decide whether to replace the tool or not. Three parameters: cutting speed, cutting feed and cutting depth are considered to modelize the tool wear. An experimental device, particularly, a work-piece in Fk20MnCr5 material was cutted on a conventional lath for shaping, a high resolution sensor (HRS), had been used for measuring wear zone. The rela- tionship between “the cutting speed, the depth of cut, the feed rate” are analysed and modelled. In order to deduce this shape the spline method to modelize the wear zone has been used and a mathematical model has been proposed.
EPS Confidentiality and Integrity mechanisms Algorithmic Approach
Ghizlane Orhanou,Said Elhajji,Youssef Bentaleb,Jalal Laassiri
International Journal of Computer Science Issues , 2010,
Abstract: The Long Term Evolution of UMTS is one of the latest steps in an advancing series of mobile telecommunications systems. Many articles have already been published on the LTE subject but these publications have viewed the subject from particular perspectives. In the present paper, a different approach has been taken. We are interested in the security features and the cryptographic algorithms used to ensure confidentiality and integrity of the transmitted data. A closer look is taken to the two EPS confidentiality and integrity algorithms based on the block cipher algorithm AES: the confidentiality algorithm EEA2 and the integrity algorithm EIA2. Furthermore, we focused on the implementation of both algorithms in C language in respect to the specifications requirements. We have tested our implementations according to the testsets given by the 3rd Generation Partnership Project (3GPP) implementation document. Some examples of the implementation tests are presented bellow.
Past environmental and climatic changes during the last 7200 cal yr BP in Adamawa plateau (Northern-Cameroun) based on fossil diatoms and sedimentary carbon isotopic records from Lake Mbalang
V. F. Nguetsop,I. Bentaleb,C. Favier,C. Martin
Climate of the Past (CP) & Discussions (CPD) , 2011, DOI: 10.5194/cp-7-1371-2011
Abstract: Past limnological conditions of Lake Mbalang (7°19′ N, 13°44′ E, altitude: 1130 m) and vegetation type were reconstructed from diatoms and sedimentary stable carbon isotope records (δ13C) since 7200 cal yr BP. The data showed that before 3600 cal yr BP, the water column was dominantly stable except around 5000–5300 cal yr BP where diatoms evidenced a mixed upper water layer and δ13C data suggest more forested vegetation in the landscape. These stable conditions can be explained by a strong monsoon flux and relatively northern position of the ITCZ that entailed high or low rainfall well distributed over the year, allowing the development of mountainous forest taxa. The decreasing trend of the monsoon flux towards the mid-Holocene was affected by several abrupt centennial to millennial-scale weakening at 6700, 5800–6000, 5000–5300, 4500 and 3600 cal yr BP. However, their impact on the vegetation is not visible, probably because rainfall distribution was favourable to forest maintenance or extension. After 3600 cal yr BP, the water column became very mixed as a result of more intense NE trade winds (Harmattan) that led at ~3000 cal yr BP to the establishment of savannah in the vegetation landscape. At that time, rainfall was probably reduced following the southward shift of the ITCZ, and the distribution of yearly rainfall was not favourable anymore to forest development. A strong seasonality with a marked dry season was established, conditions that maintained the savannah vegetation until today. Diatom data suggest the lake did not dry up during the last 7200cal yr BP; however, a low lake level observed at 2400–2100 cal yr BP is contemporaneous to a climatic event evidenced in several areas of tropical Africa and could correspond to the southernmost position of the ITCZ. Other low lake levels are observed at 1800 and 1400 cal yr BP, after which the lake rose to its present level.
Past environmental and climatic changes during the last 7200 cal yrs BP in Adamawa Plateau (Northern-Cameroun) based on fossil diatoms and sedimentary 13C isotopic records from Lake Mbalang
V. F. Nguetsop,I. Bentaleb,C. Favier,C. Martin
Climate of the Past Discussions , 2011, DOI: 10.5194/cpd-7-305-2011
Abstract: Past limnological conditions of Lake Mbalang (7°19′ N, 13°44′ E, alt: 1130 m) and vegetation type were reconstructed from diatoms and sedimentary stable carbon isotope records (δ13C) since 7200 cal yrs BP. The data showed that before 3600 yrs cal BP the water column was preferentially cold and stable except around 5000–5300 cal yrs BP where diatom evidenced mixed upper water layer, δ13C data suggest more forested vegetation in the landscape. These stable conditions can be explained by a strong monsoonal flux and correlatively northern position of the ITCZ that entailed high/low rainfall well distributed over the year to allow the development mountainous forest taxa. The decreasing trend of the monsoonal flux towards mid-Holocene was however affected by several centennial to millennial time scale abrupt weakening at 6700, 5800–6000, 5000–5300, 4500 and 3600 cal yrs BP although their impact on vegetation is not visible probably because rainfall distribution was favourable to forest maintenance or extension. After 3600 cal yrs BP, water column became very mixed as a result of more intense NE trade winds (Harmattan) that led at ~3000 cal yrs BP to the instalment of savana in the vegetation landscape. At that time, rainfall was probably reduced following the southwards shift of the ITCZ and the distribution of yearly rainfall was no more favourable to forest development. Thus a strong seasonality with a well marked dry season was established, conditions that maintained the savana vegetation till today. Diatom data suggest the lake did not dried during the last 7200 cal yrs BP, however, a low lake level observed at 2400–2100 cal yrs BP is contemporaneous to a climatic event evidenced in several areas of tropical Africa and could correspond to the southernmost position of the ITCZ. Other low lake levels are observed at 1800 and 1400 cal yrs BP, after which lake rose to its present level.
EPS Confidentiality and Integrity mechanisms Algorithmic Approach
Ghizlane Orhanou,Said El Hajji,Youssef Bentaleb,Jalal Laassiri
Computer Science , 2011,
Abstract: The Long Term Evolution of UMTS is one of the latest steps in an advancing series of mobile telecommunications systems. Many articles have already been published on the LTE subject but these publications have viewed the subject from particular perspectives. In the present paper, a different approach has been taken. We are interested in the security features and the cryptographic algorithms used to ensure confidentiality and integrity of the transmitted data. A closer look is taken to the two EPS confidentiality and integrity algorithms based on the block cipher algorithm AES: the confidentiality algorithm EEA2 and the integrity algorithm EIA2. Furthermore, we focused on the implementation of both algorithms in C language in respect to the specifications requirements. We have tested our implementations according to the testsets given by the 3rd Generation Partnership Project (3GPP) implementation document. Some examples of the implementation tests are presented bellow.
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