1,720,972 research outputs found
Conception multi-couches (PHY/MAC/NET) pour les réseaux ad hoc véhiculaires (VANETS)
No full textVehicular communication, or vehicular ad-hoc networks (VANETs), is a wireless vehicular networking technology that can support the development of Intelligent Transportation Systems (ITS). Nowadays, ITS is not only discussing about connected cars on the road but also a fully automated smart vehicle as well. Many emerging vehicle-to-everything (V2X) applications such as collision warning, traffic management, platooning, remote vehicle control, cooperative driving, and autonomous driving are already in the implementation or development phase. The new task group IEEE 802.11bd (TGbd) was recently formed to explore the future roadmap for V2X and is working toward a new standard called next-generation V2X (NGV). NGV is expected to target larger future applications that require higher throughput, operate in a higher mobility environment, and have extended communication range. Cross-Layer design is an emerging solution that supports new NGV applications. Thus, in this thesis, we propose a new cross-layer PHY/MAC/NET architecture to improve the performance of NGV applications. We begin this research by identifying enhancements to the PHY and MAC layers of other IEEE 802.11 Wi-Fi standards that could be adopted for the 802.11bd standard. Next, we propose our first contribution using a multi-layered design at the PHY/MAC/NETlayers to improve the performance of NGV applications in a higher mobility environment. The simulation results show that our proposed cross-layer solution could achieve twice the throughput improvement at MAC layer level and also could work in environment with relative speed between vehicles of up to 500 km/h, as requested by the NGV standard. However, the throughput performance decreased in dense VANETs due to the blocking problem in the MAC layer. We propose our second contribution to solve this problem by using a cross-layer design based on the selection of transmitting antennas and the adaptation of the transmitted power. The simulation results show that the proposed cross-layer design allows more vehicles to communicate simultaneously and significantly improves the average network throughput, especially for high density VANETs.La communication véhiculaire, ou réseaux ad hoc véhiculaires (VANETs), est une technologie de réseau véhiculaire sans fil qui peut soutenir le développement de systèmes de transport intelligents (STI). De nos jours, STI ne concerne pas seulement de voitures connectées sur la route, mais _egalement le véhicule intelligent entièrement automatisé. De nombreuses applications émergentes de véhicule-à-tout (V2X) telles que l'avertissement de collision, la gestion du traffic, le peloton, le contrôle de véhicule à distance, la conduite coopérative et la conduite autonome sont déjà en phase de mise en oeuvre ou de développement. Le nouveau groupe de travail IEEE 802.11bd (TGbd) a été récemment formé pour explorer la future feuille de route pour V2X et travaille actuellement sur une nouvelle norme appelée V2X de nouvelle génération (NGV). Le NGV devrait cibler des applications futures plus larges qui nécessitent un débit plus élevé et fonctionnent dans un environnement à haute mobilité avec une portée de communication étendue. La conception transversale des couches (Cross-Layer design) est une solution émergente qui permet de supporter les nouvelles applications NGV. Ainsi, nous proposons dans cette thèse une nouvelle architecture cross-layer PHY/MAC/NET pour améliorer les performances des applications NGV. Nous commençons cette recherche en identifant les améliorations des couches PHY et MAC d'autres normes Wi-Fi IEEE 802.11 qui pourraient être adoptées pour la norme 802.11bd. Ensuite, nous proposons une première contribution originale, à savoir, une architecture cross-layer PHY/MAC/NET pour améliorer les performances des applications NGV dans un environnement à mobilité élevée. Les résultats de simulation montrent que notre solution permet d'obtenir un débit deux fois plus élevé au niveau de la couche MAC dans un environnement avec une vitesse relative entre les véhicules allant jusqu'à 500 km/h, comme l'exige la norme NGV. Néanmoins, les performances en termes de débit se dégradent dans les VANETs denses en raison du problème de blocage dans la couche MAC. Pour résoudre ce problème, nous proposons une deuxième contribution cross-layer basée sur la sélection d'antennes émettrices et l'adaptation de la puissance émise. Les résultats obtenus montrent que cette conception permet à plus de véhicules de communiquer simultanément et améliore considérablement le débit moyen du réseau, en particulier pour les VANETs à haute densité
Conception multi-couches (PHY/MAC/NET) pour les réseaux ad hoc véhiculaires (VANETS)
No full textVehicular communication, or vehicular ad-hoc networks (VANETs), is a wireless vehicular networking technology that can support the development of Intelligent Transportation Systems (ITS). Nowadays, ITS is not only discussing about connected cars on the road but also a fully automated smart vehicle as well. Many emerging vehicle-to-everything (V2X) applications such as collision warning, traffic management, platooning, remote vehicle control, cooperative driving, and autonomous driving are already in the implementation or development phase. The new task group IEEE 802.11bd (TGbd) was recently formed to explore the future roadmap for V2X and is working toward a new standard called next-generation V2X (NGV). NGV is expected to target larger future applications that require higher throughput, operate in a higher mobility environment, and have extended communication range. Cross-Layer design is an emerging solution that supports new NGV applications. Thus, in this thesis, we propose a new cross-layer PHY/MAC/NET architecture to improve the performance of NGV applications. We begin this research by identifying enhancements to the PHY and MAC layers of other IEEE 802.11 Wi-Fi standards that could be adopted for the 802.11bd standard. Next, we propose our first contribution using a multi-layered design at the PHY/MAC/NETlayers to improve the performance of NGV applications in a higher mobility environment. The simulation results show that our proposed cross-layer solution could achieve twice the throughput improvement at MAC layer level and also could work in environment with relative speed between vehicles of up to 500 km/h, as requested by the NGV standard. However, the throughput performance decreased in dense VANETs due to the blocking problem in the MAC layer. We propose our second contribution to solve this problem by using a cross-layer design based on the selection of transmitting antennas and the adaptation of the transmitted power. The simulation results show that the proposed cross-layer design allows more vehicles to communicate simultaneously and significantly improves the average network throughput, especially for high density VANETs.La communication véhiculaire, ou réseaux ad hoc véhiculaires (VANETs), est une technologie de réseau véhiculaire sans fil qui peut soutenir le développement de systèmes de transport intelligents (STI). De nos jours, STI ne concerne pas seulement de voitures connectées sur la route, mais _egalement le véhicule intelligent entièrement automatisé. De nombreuses applications émergentes de véhicule-à-tout (V2X) telles que l'avertissement de collision, la gestion du traffic, le peloton, le contrôle de véhicule à distance, la conduite coopérative et la conduite autonome sont déjà en phase de mise en oeuvre ou de développement. Le nouveau groupe de travail IEEE 802.11bd (TGbd) a été récemment formé pour explorer la future feuille de route pour V2X et travaille actuellement sur une nouvelle norme appelée V2X de nouvelle génération (NGV). Le NGV devrait cibler des applications futures plus larges qui nécessitent un débit plus élevé et fonctionnent dans un environnement à haute mobilité avec une portée de communication étendue. La conception transversale des couches (Cross-Layer design) est une solution émergente qui permet de supporter les nouvelles applications NGV. Ainsi, nous proposons dans cette thèse une nouvelle architecture cross-layer PHY/MAC/NET pour améliorer les performances des applications NGV. Nous commençons cette recherche en identifant les améliorations des couches PHY et MAC d'autres normes Wi-Fi IEEE 802.11 qui pourraient être adoptées pour la norme 802.11bd. Ensuite, nous proposons une première contribution originale, à savoir, une architecture cross-layer PHY/MAC/NET pour améliorer les performances des applications NGV dans un environnement à mobilité élevée. Les résultats de simulation montrent que notre solution permet d'obtenir un débit deux fois plus élevé au niveau de la couche MAC dans un environnement avec une vitesse relative entre les véhicules allant jusqu'à 500 km/h, comme l'exige la norme NGV. Néanmoins, les performances en termes de débit se dégradent dans les VANETs denses en raison du problème de blocage dans la couche MAC. Pour résoudre ce problème, nous proposons une deuxième contribution cross-layer basée sur la sélection d'antennes émettrices et l'adaptation de la puissance émise. Les résultats obtenus montrent que cette conception permet à plus de véhicules de communiquer simultanément et améliore considérablement le débit moyen du réseau, en particulier pour les VANETs à haute densité
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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