837 resultados para Redes ad hoc veiculares (Redes de computadores)


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In this paper we investigate the problem of cache resolution in a mobile peer to peer ad hoc network. In our vision cache resolution should satisfy the following requirements: (i) it should result in low message overhead and (ii) the information should be retrieved with minimum delay. In this paper, we show that these goals can be achieved by splitting the one hop neighbours in to two sets based on the transmission range. The proposed approach reduces the number of messages flooded in to the network to find the requested data. This scheme is fully distributed and comes at very low cost in terms of cache overhead. The experimental results gives a promising result based on the metrics of studies.

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Amb aquest estudi pretenem que els nostres estudiants assoleixin els següents objectius: Conèixer recursos en línia que ofereixin recursos musicals per al treball específic de llenguatge musical i d’expressió vocal propis de l’àrea de música; aprofundir i millorar, a partir d’aquests recursos, els plantejaments interdisciplinaris del currículum d’educació infantil i primària

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El primer fallo de la Corte Penal Internacional ha confirmado que el Artículo 25(3) del Estatuto de Roma se basa en la teoría del dominio del hecho para hacer la distinción entre autoría y participación. Por el contrario, desde 2003, la jurisprudencia de los tribunales ad hoc construye el concepto de coautoría con base en la doctrina de la empresa criminal conjunta y emplea un criterio subjetivo de autor. En el presente texto analizaremos primero los problemas planteados por esta línea jurisprudencial de los tribunales ad hoc,para proseguir con el análisis del artículo del Estatuto de Roma que más parece asemejarse a la doctrina de la empresa criminal conjunta :el Artículo 25 (3) (d). El documento concluye que ninguna de las categorías de la empresa criminal conjunta tiene cabida en dicha disposición.

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Documento incluído en el volumen 'Experiències d'innovació educativa. Acció tutorial i formació'. En el crédito variable para la educación secundaria obligatoria 'Análisis demográfico de la localidad con el ordenador como herramienta de trabajo' se han repartido la materia a exponer dos profesores de dos disciplinas (ciencias sociales y tecnología administrativa). Trabajar en grupo con el objetivo de hacer un crédito, mejora la motivación del profesorado. Se explica la temporalización, justificación, objetivos, proceso de trabajo del grupo de profesores. Se sintetizan los resultados de la experiencia y se alude a la aplicabilidad para otros profesores. Se incluye en un anexo un test de evaluación del crédito.

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Resumen basado en el del autor. Resumen en castellano e ingl??s

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La 'Conferencia ah hoc sobre la educación de los emigrantes', se celebró bajo los auspicios del Consejo de Europa y de la Conferencia permanente de Ministros europeos de Educación, en Estrasburgo en noviembre de 1974, con asistencia de representantes de diecinueve países europeos y de organismos internacionales tales como la UNESCO y la OCDE. Esta Conferencia tenía como objetivos establecer unas conclusiones y recomendaciones sobre las acciones a emprender en este campo desde un punto de vista nacional, bilateral y multilateral. Las propuestas giraron en torno a: mejorar la situación de emigrantes y su familia, sobre todo en el plano educativo, a la llegada del país de acogida; dar garantías en materia de educación antes y durante el período de escolaridad obligatoria y proporcionar también garantías en materia de formación profesional, formación técnica y educación general de adultos y adolescentes. Las resoluciones adoptadas en la Conferencia a este respecto, fueron: 1. La mejora de la situación del emigrante y de su familia a su llegada al país de recepción, particularmente en el plano de la educación. 2. Garantías en materia de educación antes y después del periodo de escolaridad obligatoria en el país de recepción. 3. Garantías en materia de Formación Profesional, de Formación Técnica y de educación general de adultos y adolescentes.

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Traditionally, applications and tools supporting collaborative computing have been designed only with personal computers in mind and support a limited range of computing and network platforms. These applications are therefore not well equipped to deal with network heterogeneity and, in particular, do not cope well with dynamic network topologies. Progress in this area must be made if we are to fulfil the needs of users and support the diversity, mobility, and portability that are likely to characterise group work in future. This paper describes a groupware platform called Coco that is designed to support collaboration in a heterogeneous network environment. The work demonstrates that progress in the p development of a generic supporting groupware is achievable, even in the context of heterogeneous and dynamic networks. The work demonstrates the progress made in the development of an underlying communications infrastructure, building on peer-to-peer concept and topologies to improve scalability and robustness.

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In this paper we propose an enhanced relay-enabled distributed coordination function (rDCF) for wireless ad hoc networks. The idea of rDCF is to use high data rate nodes to work as relays for the low data rate nodes. The relay helps to increase the throughput and lower overall blocking time of nodes due to faster dual-hop transmission. rDCF achieves higher throughput over IEEE 802.11 distributed coordination function (DCF). The protocol is further enhanced for higher throughput and reduced energy. These enhancements result from the use of a dynamic preamble (i.e. using short preamble for the relay transmission) and also by reducing unnecessary overhearing (by other nodes not involved in transmission). We have modeled the energy consumption of rDCF, showing that rDCF provides an energy efficiency of 21.7% at 50 nodes over 802.11 DCF. Compared with the existing rDCF, the enhanced rDCF (ErDCF) scheme proposed in this paper yields a throughput improvement of 16.54% (at the packet length of 1000 bytes) and an energy saving of 53% at 50 nodes.

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To enhance the throughput of ad hoc networks, dual-hop relay-enabled transmission schemes have recently been proposed. Since in ad hoc networks throughput is normally related to their energy consumption, it is important to examine the impact of using relay-enabled transmissions on energy consumption. In this paper, we present an analytical energy consumption model for dual-hop relay-enabled medium access control (MAC) protocols. Based on the recently reported relay-enabled distributed coordination function (rDCF), we have shown the efficacy of the proposed analytical model. This is a generalized model and can be used to predict energy consumption in saturated relay-enabled ad hoc networks via energy decomposition. This is helpful in designing MAC protocols for cooperative communications and it is shown that using a relay results not only in a better throughput but also better energy efficiency.

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Given that the next and current generation networks will coexist for a considerable period of time, it is important to improve the performance of existing networks. One such improvement recently proposed is to enhance the throughput of ad hoc networks by using dual-hop relay-based transmission schemes. Since in ad hoc networks throughput is normally related to their energy consumption, it is important to examine the impact of using relay-based transmissions on energy consumption. In this paper, we present an analytical energy consumption model for dual-hop relay-based medium access control (MAC) protocols. Based on the recently reported relay-enabled Distributed Coordination Function (rDCF), we have shown the efficacy of the proposed analytical model. This is a generalized model and can be used to predict energy consumption in saturated relay-based ad hoc networks. This model can predict energy consumption in ideal environment and with transmission errors. It is shown that using a relay results in not only better throughput but also better energy efficiency. Copyright (C) 2009 Rizwan Ahmad et al.