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Artigos de revistas sobre o assunto "Communication 802.11p"
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Du, Lei, Nan Liu e Xiang-hui Song. "Evaluation of IEEE 802. 11p in Vehicular Communication via Simulation". Journal of Highway and Transportation Research and Development (English Edition) 8, n.º 1 (março de 2014): 95–100. http://dx.doi.org/10.1061/jhtrcq.0000370.
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Pishchin, Oleg Nickolaevich, e Dmitriy Sergeevich Puzankov. "Models for calculating the distribution of the electromagnetic field power level in mobile radio communication systems for short distances in summer". Vestnik of Astrakhan State Technical University. Series: Management, computer science and informatics 2024, n.º 2 (26 de abril de 2024): 111–19. http://dx.doi.org/10.24143/2072-9502-2024-2-111-119.
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The statement is substantiated that for the design of mobile radio communication systems at short distances up to 1 000 m, the main recommended calculation models have a significant error, since they were created for calcula-tions of long distances (as a rule, from 1 to 50 km) and have limitations in application. Due to the fact that at the present stage of development of mobile radio communication systems, the frequency ranges are in intensive research and use not only 900 and 1 800 MHz, but also 450-800 MHz sections, as well as from 2 100 to 6 000 MHz, which were not previously used for cellular communication systems, it is necessary to propose additional models necessary for the preliminary design of 3-5 generation systems in the range from 2 100 MHz. The range of radio waves in the ranges from 2 100 to 6 000 MHz is significantly reduced compared to the ranges of 1 800 or 900 MHz. The use of classical calculation models such as the Okumura and COST-231–Hata models at distances less than 1 km is characterized by significant errors and is not recommended by the authors of the models themselves for use at short distances. To solve this problem, new models have been developed for calculating the attenuation of radio signals designed to estimate attenuation at short distances.
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SMIRNOVA, ELENA, e OKSANA POPOVA. "TOPICAL ISSUES OF IMPLEMENTATION OF EXIT TAX AUDITS". Economic problems and legal practice 16, n.º 5 (20 de outubro de 2020): 110–15. http://dx.doi.org/10.33693/2541-8025-2020-16-5-110-115.
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Research writing purposes: to define the main questions of implementation of exit tax audits as important form of tax control and to allocate possibilities of increase in efficiency. The conclusions received during the research: the directions of increase in efficiency of exit tax audits are allocated. Exit tax audits are an effective form of tax control, however their quantity sharply decreases in view of high costs of carrying out. In it communication an important condition of their implementation is improvement of quality of the pretest analysis and the appointed tax control measures which taking into account practical activities of tax authorities allow to increase efficiency of conducting tax audits. The analysis of judicial practice allowing to estimate expediency of such actions as reclamation of documents, interrogation of the witness, conducting examination is made. The order of formation of the approximate sum of additional accruals on income tax of the organizations on the basis of calculation of indicators of accounting and tax reports is shown.
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Wardana, Wasis, Ahmad Almaarif e Adityas Widjajarto. "Vulnerability Assessment and Penetration Testing On The Xyz Website Using Nist 800-115 Standard". Syntax Literate ; Jurnal Ilmiah Indonesia 7, n.º 1 (11 de janeiro de 2022): 520. http://dx.doi.org/10.36418/syntax-literate.v7i1.5800.
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Currently the website has become an effective communication tool. However, it is essential to have vulnerabilities assessment and penetration testing using specific standards on released websites to the public for securing information. The problems raised in this research are conducting vulnerability testing on the XYZ website to analyze security gaps in the XYZ website, as well as conducting penetration testing on high vulnerabilities found. Testing was conducted using the NIST 800 – 115 Standard through 4 main stages: planning, discovery, attack, and report. Several tools were used: Nmap, OWASP ZAP, Burp Suite, and Foxy Proxy. This research results are presented and analyzed. There were seven vulnerabilities found, one high-level vulnerability, two medium-level vulnerabilities, and four low-level vulnerabilities. At the high level, SQL Injection types are found, at the medium level, Cross-Domains Misconfiguration and vulnerabilities are found, at the low level, Absence of Anti-CSRF Tokens, Incomplete or No Cache-control and Pragma HTTP Header Set, Server Leaks Information via “X-Powered-By” HTTP Response Header Field and X-Content-Type-Options Header Missing are found.
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Díaz Nosty, Bernardo. "Cambio climático, consenso científico y construcción mediática. Los paradigmas de la comunicación para la sostenibilidad". Revista Latina de Comunicación Social, n.º 64 (1 de janeiro de 2009): 99–119. http://dx.doi.org/10.4185/10.4185/rlcs-64-2009-808-99-119.
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El cambio climático, el calentamiento global y la sostenibilidad son conceptos integrados en la agenda de los medios, que reflejan preocupaciones y alertas amparadas en un amplio consenso científico. No obstante, el reflejo de la información sobre estos aspectos revela carencias en las técnicas constructivas del periodismo, además de aquellas que responden a cruces de intereses políticos, económicos y culturales. En este artículo se refiere la evolución y tendencias de los flujos informativos relativos al cambio climático, así como a las disonancias entre los mensajes científico y el mediático. También, se hace hincapié en el creciente interés de los estudios de comunicación, especialmente en el mundo anglosajón, sobre la crisis medioambiental, hasta el punto de sugerir el desarrollo de una corriente orientada a la comunicación periodística y la innovación sostenible.
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Rybickajasinska, Katarzyna, Zuzanna Szeptuch, Hubert Kubiszewski e Agnieszka Kowaluk. "Electrochemical Cycloaddition Reactions of Alkene Radical Cations – a Route Towards Cyclopropanes and Cyclobutanes". ECS Meeting Abstracts MA2023-01, n.º 41 (28 de agosto de 2023): 2325. http://dx.doi.org/10.1149/ma2023-01412325mtgabs.
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New methods to promote single-electron transfer reactions play an increasingly important role in driving modern organic chemistry. Significant advances have been made in the field of photoredox catalysis1 and synthetic organic electrochemistry2 to expand the utility of radicals in organic synthesis.3 While the initial developments in synthetic organic electrochemistry date as far back as the early 19th century, only recently has it undergone an explosive revival and it is now an important part of synthetic organic chemistry.4 Undeniably, it provides a green alternative to known and new reactive intermediates by the promotion of organic reactions under mild conditions without the necessity for excessive amounts of hazardous and wasteful oxidants and reductants, metals4 or catalysts, making chemical synthesis highly atom economical.5 Our work describes mild and efficient electrochemical methods for [2+1] and [2+2] cycloaddition reactions of alkene radical cations. Anodic oxidation of olefins produces electrophilic alkene radical cations, which further react with nucleophilic diazo compounds in a formal [2+1] cycloaddition towards cyclopropane synthesis. This methodology is also applicable for [2+2] cycloadditions with styrene derivatives, validating this efficient electrochemical system for both cyclopropane and cyclobutane ring synthesis. The advantages of this methods include the mild, metal and catalyst free conditions, simple setup, and scalability of the procedure, as well as its potential use for industrial applications since the method requires non-expensive graphite electrodes. References: a) Skubi, K. L., Blum, T. R., Yoon, T. P. Chem. Rev. 2016, 116, 17, 10035-10074. b) Romero, N. A., Nicewicz, D. A. Chem. Rev. 2016, 116, 17, 10075-10166 c) Prier, C. K., Rankic, D. A., MacMillan, D. W. C. Chem. Rev. 2013, 113, 7, 5322-5363. d) Donabauer, K., König, B. Chem. Res. 2021, 54,1, 242-252. Yan, M., Kawamata, Y., Baran, P. S. Chem Rev. 2017, 117, 21, 13230-13319. b) Zhu, C., Ang, N. W., Meyer, T. A., Qiu, Y., Ackermann, L. ACS Cent. Sci. 2021, 7, 3, 415-431. c) Pollok, D., Waldvogel, S. R. Sci. 2020, 11, 12386-12400. d) Meyer, T. H., Choi, I., Tian, C., Ackermann Chem 2020, 6, 2484-2496. e) Yan, M., Kawamata, Y., Baran, P. S. Angew. Chem. Int. Ed. 2018, 57, 4149-4155. Tay, N., Lehnherr, D., Rovis, T. Chem. Rev. 2022, 122, 2, 2487-2649. a) Kingston, C., Palkowitz, M. D., Takahira, Y., Vantourout, J. C., Peters., B. K., Kawamata, Y., Baran, P. S. Chem. Res. 2020, 53, 1, 72-83. b)Wirtanen, T. Prenzel, J-P. Tessonnier, S. R. Waldvogel Electroorganic Synthesis, Chem. Rev. 2021, 121, 10241–10270. c) Sbei, N., Hardwick, T., Ahmed, N. ACS Sustainable Chem. Eng. 2021, 9, 61-48-6169. Yuan, Y., Lei, A. Nature Communications. 2020, 802. Figure 1
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Niederhofer, H., e W. Staffen. "Features in Families and Family Relationships". Psychological Reports 90, n.º 3_suppl (junho de 2002): 1105–8. http://dx.doi.org/10.2466/pr0.2002.90.3c.1105.
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Standardized assessment of family features is not used routinely, although these factors may play an important role in the course of children's psychological disorders. The present study investigated the association among relationships within the families of 115 healthy children ( M = 8.2 yr., SD = 2.13; 70 boys, 45 girls). 115 mothers and fathers were asked to complete a standardized questionnaire assessing the family features (Familienklima-Testsystem by Schneewind, et al.) and another asking for their estimation of emotional relationships of the members of the family (Subjektives Familianbild-Test System by Mattejat). Analysis showed that the parents' ratings indicated significantly more empathic fathers as well as significantly more autonomous mothers in well-organized, conflict-free families. Our results indicate an association between families' organization and measured scores for fathers' empathy and mothers' autonomy. Sufficient intrafamilial communication is associated with roles of the parents within the family. Psychotherapeutic interventions might focus on the families' organization.
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Niederhofer, H., W. Staffen e A. Mair. "Features in Families and Family Relationships". Psychological Reports 90, n.º 3_part_2 (junho de 2002): 1105–8. http://dx.doi.org/10.1177/003329410209000309.2.
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Standardized assessment of family features is not used routinely, although these factors may play an important role in the course of children's psychological disorders. The present study investigated the association among relationships within the families of 115 healthy children ( M = 8.2 yr., SD = 2.13; 70 boys, 45 girls). 115 mothers and fathers were asked to complete a standardized questionnaire assessing the family features (Familienklima-Testsystem by Schneewind, et al.) and another asking for their estimation of emotional relationships of the members of the family (Subjektives Familianbild-Test System by Mattejat). Analysis showed that the parents’ ratings indicated significantly more empathic fathers as well as significantly more autonomous mothers in well-organized, conflict-free families. Our results indicate an association between families’ organization and measured scores for fathers’ empathy and mothers’ autonomy. Sufficient intrafamilial communication is associated with roles of the parents within the family. Psychotherapeutic interventions might focus on the families’ organization.
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Walidainy, Hubbul, Nawal Nashirah, Ramzi Adriman, Yuwaldi Away e Nasaruddin Nasaruddin. "Statistical channel model for 6G communication networks in Banda Aceh City". Radioelectronic and Computer Systems, n.º 2 (25 de maio de 2023): 65–80. http://dx.doi.org/10.32620/reks.2023.2.06.
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Wireless technology is expected to undergo considerable transformation because of the numerous services offered by 6G communication networks, which virtually entirely encompass every part of everyday life and use a variety of devices. Channel modeling is an essential factor in designing 6G communication networks. To meet the channel requirements of future 6G communication networks, it is crucial to measure the channel to consider path loss, multi-band, fading, blocking effect, multipath clustering, transmitter, and receiver moving speed/direction/time. The goal of this paper is to design and evaluate a 6G communication network in Banda Aceh City using a statistical channel model. The channel model is associated with environmental conditions such as rainfall and humidity. The method is then based on computer simulation using the NYUSIM simulator to complete the channel modeling using an operating frequency of 95 GHz with a bandwidth of 800 MHz. In the simulator, the designed 6G channel model is evaluated in both line-of-sight (LOS) and non-line-of-sight (NLOS) network environments. In addition, the designated network parameters, such as the coverage area, angle of arrival (AoA), angle of departure (AoD), and power delay profile (PDP), are simulated. The results, at AoA, the value of received power for LOS conditions ranges from -86 dBm to -101 dBm, while the value for NLOS conditions ranges from -91 dBm to -111 dBm. Under LOS conditions, the received power for AoD ranges from -86 dBm to -101 dBm, whereas under NLOS conditions, it ranges from -91 dBm to -111 dBm. In the omnidirectional PDP, the pathloss value for the LOS condition is 99.8 dB and the delay is 17.9 ns, while the pathloss value for the NLOS condition is 104.2 dB with a delay of 28.1 ns. For the directional PDP, the LOS condition yields a path loss of 106.4 dB and a delay of 2.9 ns, while the NLOS condition yields a path loss of 110.5 dB and a delay of 3 ns. Conclusions. The simulation indicated that the AoA, AoD, and PDP in terms of received power, pathloss, and propagation delay are in acceptable conditions for a 6G network in Banda Aceh City in the two observed environments. Therefore, it is conceivable to establish a 6G network in Banda Aceh City in the future.
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Yamamoto, Emiko, Maki Kanaoka, Takayuki Nemoto, Yumiko Kinoshita, Ryu Takeya e Toshihiko Yanagita. "Effectiveness of Interprofessional Education Based on the Case-and Communication-Based Approach". IAFOR Journal of Psychology & the Behavioral Sciences 9, n.º 2 (29 de março de 2024): 39–53. http://dx.doi.org/10.22492/ijpbs.9.2.03.
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Pharmacology role-playing, which follows a case and communication (C & C)-based approach, has been developed for use in medical education, and its learning effects have been reported. To cultivate team spirit among medical professionals from an early stage, we proposed developing the C & C approach for interprofessional education (IPE). Therefore, this study aimed to examine the learning effects of the C & C approach during joint classes of medical and nursing students. In December 2017, we employed the C & C approach to simulate a scenario in which drugs were explained to patients, and responses were collected from 103/115 medical (90%) and 55/60 nursing students (92%). The questionnaires used were designed to evaluate the following five items: understanding pharmacotherapy, understanding patients’ feelings, learning motivation, change in learning attitudes, and understanding IPE. Open-ended questions on learning content were analyzed based on free-text responses. Each student group acknowledged the effectiveness of the approach and the importance of cooperation. In total, 80.2% of medical students and 76.3% of nursing rated “understanding of IPE” as “very effective/effective.” Participants learned about the disparity in perspectives, with medical students gaining insight into nursing students’ approaches to patient interactions, and nursing students acquiring an understanding of doctors’ perspectives on disease and medical treatment. In conclusion, the C & C approach proved beneficial as an IPE method, raising awareness among both nursing and medical students about the significance of communication skills and patient perspectives.
Teses / dissertações sobre o assunto "Communication 802.11p"
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Gukhool, Balkrishna Sharma. "Communication continue en mode infrastructure dans les réseaux véhiculaires utilisant IEEE 802.11P". Mémoire, Université de Sherbrooke, 2009. http://savoirs.usherbrooke.ca/handle/11143/1543.
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Les handovers sont des phénomènes inévitables dans les réseaux sans-fil mobiles. Lors du passage d'une station mobile d'un point d'accès à un autre, le handover affecte la qualité des transmissions, et ainsi, il est néfaste à la performance des réseaux sans-fil. De nombreuses techniques de réduction du délai lié au handover ont été proposées, mais la plupart ne sont pas adaptées aux attentes du nouveau type de réseau sans-fil mobile qu'est le réseau véhiculaire. Ce travail propose donc l'implémentation d'une méthode de réduction du délai encouru lors d'un handover dans les réseaux véhiculaires qui opèrent sous une technologie d'accès sans-fil adaptée pour les besoins des réseaux véhiculaires. Le travail est composé de deux blocs : le premier est l'implémentation d'IEEE 802.11p, qui est une variante de la norme générique d'IEEE 802.11 et qui est développée spécialement pour l'accès dans les réseaux véhiculaires, dans un simulateur de réseaux. L'autre partie concerne le choix d'une méthode de réduction du délai lié à l'étape de la recherche du handover. En tenant compte des réalités technologiques, le choix s'est porté sur une technique préconisant l'utilisation des cache pour contenir et diffuser de l'information sur les points d'accès avoisinants. La méthode proposée a été testée et a donné de très bons résultats réalistes. L'intégration des modules complémentaires pour refléter l'ensemble de la technique proposée au niveau du simulateur s'est aussi faite sans problèmes majeurs.
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Martínez, Domínguez Francisco José. "Improving Vehicular ad hoc Network Protocols to Support Safety Applications in Realistic Scenarios". Doctoral thesis, Universitat Politècnica de València, 2011. http://hdl.handle.net/10251/9195.
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La convergencia de las telecomunicaciones, la informática, la tecnología inalámbrica y los sistemas de transporte, va a facilitar que nuestras carreteras y autopistas nos sirvan tanto como plataforma de transporte, como de comunicaciones. Estos cambios van a revolucionar completamente cómo y cuándo vamos a acceder a determinados servicios, comunicarnos, viajar, entretenernos, y navegar, en un futuro muy cercano. Las redes vehiculares ad hoc (vehicular ad hoc networks VANETs) son redes de comunicación inalámbricas que no requieren de ningún tipo de infraestructura, y que permiten la comunicación y conducción cooperativa entre los vehículos en la carretera. Los vehículos actúan como nodos de comunicación y transmisores, formando redes dinámicas junto a otros vehículos cercanos en entornos urbanos y autopistas.
Las características especiales de las redes vehiculares favorecen el desarrollo de servicios y aplicaciones atractivas y desafiantes. En esta tesis nos centramos en las aplicaciones relacionadas con la seguridad. Específicamente, desarrollamos y evaluamos un novedoso protocol que mejora la seguridad en las carreteras. Nuestra propuesta combina el uso de información de la localización de los vehículos y las características del mapa del escenario, para mejorar la diseminación de los mensajes de alerta. En las aplicaciones de seguridad para redes vehiculares, nuestra propuesta permite reducir el problema de las tormentas de difusión, mientras que se mantiene una alta efectividad en la diseminación de los mensajes hacia los vehículos cercanos.
Debido a que desplegar y evaluar redes VANET supone un gran coste y una tarea dura, la metodología basada en la simulación se muestra como una metodología alternativa a la implementación real. A diferencia de otros trabajos previos, con el fin de evaluar nuestra propuesta en un entorno realista, en nuestras simulaciones tenemos muy en cuenta tanto la movilidad de los vehículos, como la transmisión de radio en entornos urbanos, especialmente cuando los edificios interfieren en la
propagación de la señal de radio. Con este propósito, desarrollamos herramientas
para la simulación de VANETs más precisas y realistas, mejorando tanto la modelización de la propagación de radio, como la movilidad de los vehículos, obteniendo
una solución que permite integrar mapas reales en el entorno de simulación. Finalmente,
evaluamos las prestaciones de nuestro protocolo propuesto haciendo uso
de nuestra plataforma de simulación mejorada, evidenciando la importancia del
uso de un entorno de simulación adecuado para conseguir resultados más realistas
y poder obtener conclusiones más significativas.Martínez Domínguez, FJ. (2010). Improving Vehicular ad hoc Network Protocols to Support Safety Applications in Realistic Scenarios [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/9195
Palancia
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Manshaei, Mohammad Hossein. "Cross layer interactions for adaptive communications in IEEE 802. 11 wireless LANs". Nice, 2005. http://www.theses.fr/2005NICE4105.
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Cette thèse a pour objectif l´étude des mécanismes d´interaction inter-couche et leurs applications pour des algorithmes adaptatifs pour contrôler les paramètres de transmission. Après une description rapide des protocoles des couches liaison et physiques du standard IEEE 802. 11, nous présentons une analyse de performance des modes de transmission spécifiés par les normes 802. 11a/b. La deuxième contribution de cette thèse porte sur la modélisation des réseaux 802. 11. Nous proposons un modèle analytique qui prend en compte la position des terminaux radio par rapport au point d´accès afin d´évaluer les performances de la couche MAC. Nous proposons ensuite de nouveaux mécanismes de sélection du débit de transmission physique. Nous avons élaboré l´algorithme AARF, basé sur l´algorithme ARF, qui s´intéresse à la classe des terminaux dits à faible latence et offre des services d´adaptation à court et à long terme. Un autre algorithme basé sur les mêmes idées que celles développées pour AARF, mais conçu pour fonctionner avec des systèmes à grande latence, a été implanté et expérimenté sur des terminaux à base du processeur Atheros. Enfin, nous avons élaboré un troisième algorithme de contrôle dynamique du mode de transmission en boucle fermée appelé CLARA qui est compatible avec les standards 802. 11a/b/g. La dernière contribution de cette thèse porte sur l´optimisation de la transmission de flots multimédias temps réel sur des réseaux 802. 11. Nous présentons MORSA, un mécanisme d´optimisation inter-couche efficace qui permet de sélectionner le mode de transmission à utiliser en fonction de l´état du canal de transmission et des caractéristiques de l´applicationThe main goal of this thesis is to propose efficient adaptive communication mechanisms using cross layer interactions in IEEE 802. 11 WLANs. First, we present a detailed performance evaluation of 802. 11a/b PHY layer transmission modes. The second contribution of the thesis concerns 802. 11 MAC/PHY layers modelling. An analytical model that accounts for the positions of stations with respect to the access point while evaluating the performance of 802. 11 MAC layer, has been proposed. The third contribution of the thesis concerns rate adaptation mechanisms and especially cross layer algorithms between MAC and PHY layers. An adaptive rate selection algorithm, called AARF for low latency systems that improves upon ARF to provide both short-term and long-term adaptation has been proposed. In this field, we also present a new rate adaptation algorithm designed for high latency systems named AMRR that has been implemented and evaluated on an AR5212-based device. We then propose a closed-loop, dynamic rate selection algorithm that can be implemented in all 802. 11a/b/g compliant wireless local area networks. This algorithm called CLARA is a culmination of the best attributes of the transmitter-based ARF and the RBAR control mechanisms with additional practical features to facilitate multipath fading channel sensing and feedback control signalling. The last contribution of the thesis is on the optimization of real time multimedia transmission over 802. 11 based networks. In particular, we propose a simple and efficient cross layer mechanism, called MORSA, for dynamically selecting the transmission mode considering both the channel conditions and characteristics of the media
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Dhoutaut, Dominique. "Etude du standard IEEE 802. 11 dans le cadre des réseaux ad hoc". Lyon, INSA, 2003. http://theses.insa-lyon.fr/publication/2003ISAL0094/these.pdf.
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Les réseaux ad hoc constitués de mobiles ne s'appuient sur aucune infrastructure fixe et s'auto-organisent au gré des mouvements. Dans ce domaine de recherche récent, la majeure partie de l'activité est tournée vers le routage. De part sa disponibilité commerciale et sa facilité d'utilisation, la norme IEEE 802. 11(Wi-Fi) est en général choisie comme support dans de nombreux travaux de recherche sur le routage. Mais 802. 11 n'a pas été conçue pour le contexte des réseaux multi-sauts et présente des limites que nous nous attachons à mettre en lumière. Par simulation puis par expérimentation réelle, nous soulevons un certain nombre de problèmes, allant de l'équité dans l'accès au canal aux problèmes de portée et d'impact de l'environnement. Grâce à une étude détaillée de ces divers phénomènes, cette thèse a un impact en particulier sur les protocoles de routage ad hoc et la manière dont ils sont élaborés, mais aussi sur d'autres protocoles de niveau supérieur, à commencer par TCPStudy of the IEEE 802. 11 standard un ad hoc networks context: from simulation to experimentation. The mobiles composing ad hoc networks do not rely on any fixed infrastructure and organise themselves depending on nodes movements. This research area is quite recent, and most of the work concerns routing. Because of its commercial availability and its ease of use, IEEE 802. 11 standard (Wi-Fi) is generally chosen to develop and test ad hoc routing protocols. But 802. 11 has not been originally designed for multi-hops networks and has limitations in this context that we intend to highlight. Using simulations then real world experimentations, we bring up many problems ranging from medium access equity to transmission range and environment impact. With its detailed study of these phenomena, this PhD has an impact in particular over ad hoc routing protocols and the way they are designed, but also over upper layers protocols, TCP being the first of them
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Sarr, Cheikh. "De l'apport d'une évaluation précise des ressources pour la Qualité de Service des réseaux ad hoc basés sur IEEE 802. 11". Lyon, INSA, 2007. http://theses.insa-lyon.fr/publication/2007ISAL0046/these.pdf.
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L’essor des technologies sans fil offre aujourd’hui de nouvelles perspectives dans le domaine des télécommunications. L’évolution récente des moyens de communication sans fil permet la manipulation de l’information par des unités de calculs portables accédant au réseau via une interface de communication sans fil. Depuis quelques années, les réseaux ad hoc, réseaux sans fil ne possédant aucune infrastructure fixe dédiée à la gestion des communications, ont suscité un axe de recherche important. Les débits de ces réseaux sont actuellement tels que des applications contraignantes comme la diffusion de vidéos ou la téléphonie sur IP sont envisageables sur ces réseaux. La mise en place de qualité de service dans les réseaux ad hoc est donc une problématique clé. Pendant ma thèse, je me suis intéressé à l’évaluation des ressources disponibles dans les réseaux ad hoc. Cette problématique, trop souvent laissée de côté, est pourtant fondamentale si on veut pouvoir offrir des garanties aux applications de manière efficace. J’ai donc proposé une technique d’évaluation de la bande passante disponible qui présente de très bonnes performances et qui permet d’assurer avec précision les garanties demandées par les applications avec contraintes. A partir de cette estimation, je me suis intéressé à la cohabitation entre les flux QoS et les flux Best Effort, afin de pouvoir accepter le maximum de flux QoS d’une part et d’optimiser la gestion de la bande passante dans le réseau d’autre part. Enfin, cette estimation m’a aussi permis de proposer une évaluation fiable du délai moyen sur un chemin. Cette estimation peut être utilisée au sein d’un protocole de routage garantissant des délais moyen aux applicationsMobile Ad hoc Network (MANET) is an autonomous system of mobile nodes connected by wireless links. They require no fixed infrastructure such as base station to operate; therefore, it is an attractive networking option for connecting mobile devices quickly and spontaneously. The nodes themselves address topology changes due to the mobility, the arrival or the departure of nodes. Today, several applications general multimedia data or rely on the proper transmission of sensitive control traffic. These applications may benefit from a quality of service (QoS) support. Therefore, this field has been extensive/y studied and more and more QoS solutions are proposed for ad hoc networks. During my thesis, I focus on one of the fundamental resources, the bandwidth. Estimating the remaining bandwidth at a given time an in a given part of the network is tricky, as the medium is shared between close nodes in a wireless network. This implies that computation of the available bandwidth between two neighbor nodes requires identification of all the emitter's potential contenders and of all the receiver's potential jammers. I propose therefore a new technique to estimate residual bandwidth in ad hoc networks which present good performances. From this estimation, i have also developed a management scheme for QoS and Best Effort flows in order to increase the acceptance rate of QoS flows. Finally, we also compute an evaluation of end-to-end delay in these ad hoc networks
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Nivor, Frédéric. "Architecture de Communication pour les Applications Multimédia Interactives dans les Réseaux Sans Fil". Phd thesis, Université Paul Sabatier - Toulouse III, 2009. http://tel.archives-ouvertes.fr/tel-01067146.
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Les travaux de cette thèse s'inscrivent dans le contexte des réseaux sans fil et des réseaux d'accès par Satellite en particulier, qui facilitent l'installation d'infrastructures réseau dans les zones géographiquement reculées et faiblement peuplées. Cependant, ces derniers présentent certains inconvénients lorsqu'il s'agit de déployer des applications multimédia interactives. En effet, de telles applications requièrent un délai de bout en bout aussi faible que possible et plus généralement exigent une meilleure Qualité de Service (QdS) du système de communication que le classique Meilleur-Effort (BE) afin de fonctionner correctement. Or, les réseaux d'accès par satellite géostationnaires souffrent déjà d'un délai de propagation non négligeable d'autant plus accru que la transmission des données est assurée par des mécanismes d'allocation dynamique, par exemple dans un système DVB-S2/RCS. Dans ces travaux de thèse, nous proposons d'utiliser les informations de signalisation de session des applications multimédia basées sur le protocole de session SIP afin d'ajuster le paramétrage du système de communication selon une approche " cross-layer " qui permet alors d'améliorer de façon significative la réactivité du système. Nous avons proposé plusieurs solutions pour, d'abord réduire le temps entre la demande de communication et le démarrage effectif du transfert des flux multimédia, ensuite réduire le délai de transmission des données multimédia durant la communication (tout en utilisant de manière optimale les ressources réseau disponibles sur la voie retour), et enfin accroître le nombre de flux multimédia admissibles dans le réseau satellite tout en leur garantissant un niveau de QdS satisfaisant. Afin de faciliter l'intégration et l'implémentation des solutions proposées dans un système de communication réel, un mécanisme de communication inter-couches d'optimisation est proposé et développé. De plus, une architecture orientée web services est utilisée afin de faciliter la découverte et l'invocation des différentes niveaux de services de communication présents dans de tels réseaux d'accès. Les solutions proposées ont été évaluées dans des environnements sans fil émulés et réels
Livros sobre o assunto "Communication 802.11p"
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Hotspot Networks. New York: McGraw-Hill, 2003.
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Stacey, Robert, e Eldad Perahia. Next Generation Wireless LANs: 802. 11n And 802. 11ac. Cambridge University Press, 2013.
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Stacey, Robert, e Eldad Perahia. Next Generation Wireless LANs: 802. 11n And 802. 11ac. Cambridge University Press, 2013.
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Stacey, Robert, e Eldad Perahia. Next Generation Wireless LANs: 802. 11n And 802. 11ac. Cambridge University Press, 2013.
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Next Generation Wireless LANs: 802. 11n and 802. 11ac. Cambridge University Press, 2013.
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Geier, Jim. Designing and Deploying 802. 11 Wireless Networks: A Practical Guide to Implementing 802. 11n and 802. 11ac Wireless Networks for Enterprise-Based Applications. Cisco Press, 2015.
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Geier, Jim. Designing and Deploying 802. 11 Wireless Networks: A Practical Guide to Implementing 802. 11n and 802. 11ac Wireless Networks for Enterprise-Based Applications. Cisco Press, 2015.
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Stacey, Robert, e Eldad Perahia. Next Generation Wireless Lans: Throughput, Robustness, and Reliability In 802. 11N. Cambridge University Press, 2008.
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Stacey, Robert, e Eldad Perahia. Next Generation Wireless LANs: Throughput, Robustness, and Reliability In 802. 11n. Cambridge University Press, 2008.
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Stacey, Robert, e Eldad Perahia. Next Generation Wireless LANs: Throughput, Robustness, and Reliability In 802. 11n. Cambridge University Press, 2008.
Encontre o texto completo da fonteCapítulos de livros sobre o assunto "Communication 802.11p"
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Fernandes, Joana Filipa Teixeira, Diamantino Rui Freitas e João Paulo Teixeira. "Accuracy Optimization in Speech Pathology Diagnosis with Data Preprocessing Techniques". In Communications in Computer and Information Science, 287–99. Cham: Springer Nature Switzerland, 2024. http://dx.doi.org/10.1007/978-3-031-53025-8_20.
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AbstractUsing acoustic analysis to classify and identify speech disorders non-invasively can reduce waiting times for patients and specialists while also increasing the accuracy of diagnoses. In order to identify models to use in a vocal disease diagnosis system, we want to know which models have higher success rates in distinguishing between healthy and pathological sounds. For this purpose, 708 diseased people spread throughout 19 pathologies, and 194 control people were used. There are nine sound files per subject, three vowels in three tones, for each subject. From each sound file, 13 parameters were extracted. For the classification of healthy/pathological individuals, a variety of classifiers based on Machine Learning models were used, including decision trees, discriminant analyses, logistic regression classifiers, naive Bayes classifiers, support vector machines, classifiers of closely related variables, ensemble classifiers and artificial neural network classifiers. For each patient, 118 parameters were used initially. The first analysis aimed to find the best classifier, thus obtaining an accuracy of 81.3% for the Ensemble Sub-space Discriminant classifier. The second and third analyses aimed to improve ground accuracy using preprocessing methodologies. Therefore, in the second analysis, the PCA technique was used, with an accuracy of 80.2%. The third analysis combined several outlier treatment models with several data normalization models and, in general, accuracy improved, obtaining the best accuracy (82.9%) with the combination of the Greebs model for outliers treatment and the range model for the normalization of data procedure.
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"TRADE AND COMMUNICATION IN EASTERN EUROPE, A.D. 800-1200". In Travel & Travellers Middle Ages, 124–43. Routledge, 2013. http://dx.doi.org/10.4324/9780203040157-11.
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El Louadi, Mohamed. "The Arab World, Culture and Information Technology". In Information Communication Technologies, 151–59. IGI Global, 2008. http://dx.doi.org/10.4018/978-1-59904-949-6.ch012.
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In 801, Harun Rashid offered Charlemagne a water clock, the like of which was inexistent in all of Europe at that time; the King’s court thought that a little devil was hidden inside the clock. In the 1930s, King Abdulaziz of Saudi Arabia had to convince his people that the radio was not the making of the devil and that it could in fact be used to broadcast and spread the Quran. In 2003, the Arab region is found to be still lagging in modern technologies adoption (UNDP, 2003). Thus, in a little more than 11 centuries, the Arabs were transformed from leaders to adopters, then to late adopters as far as technologies are concerned.
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Bruce, Steve. "Style and Presentation in the 18th Century". In Communicating Science, 68–91. Oxford University PressNew York, NY, 2002. http://dx.doi.org/10.1093/oso/9780195134544.003.0005.
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Abstract The 80th issue of Philosophical Transactions features a 12-page article by an up-and-coming young scientist, Isaac Newton—his first scientific publication and the first major scientific article in English. The Transactions editor received this article on 6 February 1672 and published it with minor revisions less than two weeks later. The initial reception of Newton’s article was largely positive: it had an early impact on thinking about light and color in England and on the Continent, and though hotly contested on many fronts (see Bazerman 1988, pp. 80-127; Gross 1990, pp. 111-128; Westfall 1993, pp. 85-109), it was taken seriously by the prominent natural philosophers in England and Europe. Newton’s main contention was that white light, far from being simple, as previously believed, was a compound of all the colors of the spectrum, a compound that could be decomposed by passing white light through a prism and recomposed through reversing that passage in a second prism.
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Chow, C., H. Leong e A. Chan. "Peer-to-Peer Cooperative Caching in Mobile Environments". In Encyclopedia of Mobile Computing and Commerce, 749–53. IGI Global, 2007. http://dx.doi.org/10.4018/978-1-59904-002-8.ch126.
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An infrastructure-based mobile environment is formed with a wireless network connecting mobile hosts (MHs) and mobile support stations (MSSs). MHs are clients equipped with portable devices, such as laptops, personal digital assistants, cellular phones, and so on, while MSSs are stationary servers providing information access for the MHs residing in their service areas. With the recent widespread deployment of contemporary peer-to-peer (known as P2P throughout this chapter) wireless communication technologies, such as IEEE 802.11 (IEEE Standard 802-11, 1997) and Bluetooth (Bluetooth SIG, 2004), coupled with the fact that the computation power and storage capacity of most portable devices have been improving at a fast pace, a new information sharing paradigm known as P2P information access has rapidly taken shape. The MHs can share information among themselves rather than having to rely solely on their connections to the MSS. This article reviews a hybrid communication framework - that is, mobile cooperative caching - which combines the P2P information access paradigm into the infrastructure-based mobile environment.
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El Louadi, Mohamed. "The Arab World, Culture and Information Technology". In Encyclopedia of Developing Regional Communities with Information and Communication Technology, 21–27. IGI Global, 2005. http://dx.doi.org/10.4018/978-1-59140-575-7.ch005.
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In 801, Harun Rashid offered Charlemagne a water clock, the like of which was inexistent in all of Europe at that time; the King’s court thought that a little devil was hidden inside the clock. In the 1930s, King Abdulaziz of Saudi Arabia had to convince his people that the radio was not the making of the devil and that it could in fact be used to broadcast and spread the Quran. In 2003, the Arab region is found to be still lagging in modern technologies adoption (UNDP, 2003). Thus, in a little more than 11 centuries, the Arabs were transformed from leaders to adopters, then to late adopters as far as technologies are concerned.
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"Fishery Resources, Environment, and Conservation in the Mississippi and Yangtze (Changjiang) River Basins". In Fishery Resources, Environment, and Conservation in the Mississippi and Yangtze (Changjiang) River Basins, editado por Huatang Deng, Jiawen Ba e Daqing Chen. American Fisheries Society, 2016. http://dx.doi.org/10.47886/9781934874448.ch2.
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<em>Abstract</em>.—The Yangtze River is the largest river in China, with a drainage area encompassing a land area of 1.8 × 10<sup>6</sup> km<sup>2</sup>. The river main stem flows approximately 6,300 km from west to east through 11 provinces, eventually emptying into the East China Sea. The total basin area of the Yangtze River provides more than 40% of China’s gross domestic product, sustains nearly 500 million people, and plays a vital role in the overall socioeconomic development of China. Because of longitudinal differences in geomorphology, the Yangtze River is often divided into upper, middle, and lower reaches for the purposes of study and description. In general, the Yangtze River basin has a warm climate and abundant rainfall. The subtropical monsoon climate accounts for 70–80% of its annual rainfall, which produces predictable annual flood events during summers of each year. The Yangtze River ecosystem also has diverse aquatic habitats that support high biodiversity. The Yangtze River main stem contains more than 3,000 tributaries and approximately 4,000 lakes that provide important habitats for thousands of aquatic species, which include 378 fish species. Yet, the ecological communities of the Yangtze River have been dramatically impacted in recent decades due to high degrees of anthropogenic activities associated with the economic development of China. Significant biodiversity declines occurring throughout the basin have been largely attributed to hydropower dam construction, overexploitation of major fisheries, water pollution, and habitat fragmentation. In addition, widespread disconnection of the Yangtze River main stem from its floodplain lakes, lake reclamation projects, invasions by exotic species, and other serious ecological problems threaten the survival of the remaining aquatic resources in the basin. To offset the adverse effects of these threats, a number of nature reserves have been established. Additionally, protection and restoration measures, including spring fishing closures, artificial population enhancement strategies, and complete habitat restoration projects, have been implemented throughout the basin. Although these projects have yielded some encouraging results to date, they are still considered inadequate. It is recommended that an integrated strategy that includes cross-functional communication mechanisms, more comprehensive monitoring, ecological rehabilitation, and government legislation is still needed. This will insure that utilization and development in the Yangtze River ecosystem are sustainable and balanced with conservation and ecological needs.
Trabalhos de conferências sobre o assunto "Communication 802.11p"
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Lauder, R. D. T., A. C. Tropper, D. C. Hanna R. M. Percival, D. Szebesta e R. Wyatt. "A diode-pumped, first window optical fibre amplifier providing up to +12 dBm of output". In The European Conference on Lasers and Electro-Optics. Washington, D.C.: Optica Publishing Group, 1994. http://dx.doi.org/10.1364/cleo_europe.1994.cmm7.
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The thulium ion is one of great interest when it is doped within fluorozirconate glass due to the number of transitions available for stimulated emission. One such transition is the 3F4 to 3H6 transition at 0.8µm. This is of interest as it lies within the first window for optical communication. There is growing interest in the use of this window for local area networks, passive optical networks, or supervisory systems. Small signal amplification of up to 23 dB has been reported for this transition in a thulium-doped fluoride fibre using a Ti:sapphire laser as the pump source.1 We report here the first diodepumped operation of this optical amplifier. An intrinsic small signall gain in excess of 30 dB was achieved. With a launched 807-nm signal power of -10 dBm, intrinsic gain of 21 dB was observed, producing amplified output powers of +11 dBm. An intrinsic gain of greater than 20 dB was observed for signals over the spectral range of 802 nm to 810 nm. The greatest amplified output power obtained for this system was 12.8 dBm for 30 mW of launched diode pump power.
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Chen, Xin-Yu, Wei Ding, Ying-Ying Wang, Shou-Fei Gao, Fei-Xiang Xu, Hui-Chao Xu, Yi-Feng Hong, Yi-Zhi Sun, Pu Wang e Lijian Zhang. "Towards polarization-based, low-latency quantum communication over hollow-core conjoined-tube fibers at around 800 nm". In CLEO: Applications and Technology. Washington, D.C.: OSA, 2020. http://dx.doi.org/10.1364/cleo_at.2020.jw2a.11.
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Ajisafe, Foluke, Mark Reid, Hank Porter, Lydia George, Rhonna Wu, Kira Yudina, Alejandro Pena, Efe Ejofodomi e Pedro Artola. "Infill Well Completion Technologies Mitigate Well Interference and Optimize Production on Multiwell Pad". In SPE Hydraulic Fracturing Technology Conference and Exhibition. SPE, 2021. http://dx.doi.org/10.2118/204181-ms.
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Abstract Increased drilling of infill wells in the Bakken has led to growing concern over the effects of frac or fracture hits between parent and infill wells. Fracture hits can cause decreased production in a parent well, as well as other negative effects such as wellbore sanding, casing damage, and reduced production performance from the infill well. An operator had an objective to maximize production of infill wells and decrease the frequency and severity of frac hits to parent wells. The goal was to maintain production of the parent wells and avoid sanding, which had the potential to cause cleanouts. Infill well completion technologies were successfully implemented on multiwell pads in Mountrail County, Williston basin, to minimize parent-child well interference or negative frac hits on parent wells for optimized production. Four infill (child) wells were landed in the Three Forks formation directly below a group of six parent wells landed in the Middle Bakken. The infill well completion technologies used in this project to mitigate frac hits included far-field diverter, near-wellbore diverter, and real-time pressure monitoring. The far-field diverter design includes a blend of multimodal particles to bridge the fracture tip, preventing excessive fracture length and height growth. The near-wellbore diverter consists of a proprietary blend of degradable particles with a tetra modal size distribution and fibers used to achieve sequential stimulation of perforated clusters to maximize wellbore coverage. Hydraulic fracture modeling with a unique advanced particle transport model was used to predict the impact of the far-field diverter design on fracture geometry. Real-time pressure monitoring allowed acquisition of parent well pressure data to identify pressure communication or lack of communication and implement mitigation and contingency procedures as necessary. Real-time pressure monitoring was also used to optimize and validate the far-field diversion design during the job execution. The parent well monitored was 800 ft away from the closest infill well and at high risk for frac hits due to both the proximity to the infill well and depletion. In the early stages of the infill well stimulation, an increase in pressure up to 600 psi was observed in the parent well. The far-field diverter design was modified to combat the observed frac hit, after which a noticeable drop in both frequency and magnitude of frac hits was observed on the parent well. This is the first time the far-field diverter design optimization process was done in real time. After the infill wells stimulation treatment, production results showed a positive uplift in oil production for all parent wells at an average of 118%. Also, only two out of seven parent wells required a full cleanout, resulting in savings in well cleanup costs. Infill well production data was compared with the closest parent well landed in the same formation (Three Forks). At about a year, the best infill well production was only 10% less than the parent well with similar completion design and the average infill well production approximately 18% less than the parent well. Considering the depletion surrounding the infill wells, production performance exceeded expectations.