Telecommunication Systems
Mostrando 13-24 de 76 artigos, teses e dissertações.
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13. Gestão de segurança da informação - uma proposta para potencializar a efetividade da segurança da informação em ambiente de pesquisa científica / Information security management a proposal to improve the effectiveness of information security in the scientific research environment
The increase of the connectivity in the business environment, combined with the growing dependency of information systems, has become the information security management an important governance tool. Information security has as main goal to protect the business transactions in order to work normally. In this way, It will be safeguarding the business continui
IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia. Publicado em: 30/11/2009
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14. Metodo de analise de trafegos VoIP sobrepostos / Method of analysis of VoIP traffic over
The behavior of VoIP traffic in network links is addressed in this work. VoIP applications have strict requirements for quality of service (QoS) that should be provided for in the network design. In this sense, the Markov Modulated Poisson Process (MMPP) is displayed as model of process of arrivals that is appropriate to characterize the behavior of superpos
Publicado em: 2009
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15. The impact of urbanization on the distribution of lightning induced voltages on overhead lines / O impacto do aumento da urbanização nos niveis das tensões induzidas por descargas atmosfericas nas proximidades de linhas de transmissão
Some of the worst damage caused by lightning is indirect, that is, it is caused by electromagnetic fields radiated from this kind of natural phenomenon resulting in electromagnetic compatibility problems or in challenges for designers of surge protection systems and shields against these interferences. This work considers one of these indirect effects, induc
Publicado em: 2009
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16. IPTV architecture with time-shift support based on peer-to-peer distribution. / Arquitetura de IPTV com suporte à apresentação deslocada no tempo baseada em distribuição peer-to-peer.
Telecommunication companies are suffering from the increasing offer of cheap and reliable voice over IP services, being forced to diversify their services looking for new revenue possibilities. Since these companies have a vast infrastructure, they are now providing TV services through the same telephony and data infrastructure, using their IP networks to of
Publicado em: 2009
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17. Study of special modulation formats for optical communication / Estudo de formatos especiais na modulação digital para comunicações ópticas
This MSc thesis investigates optical modulation formats as an alternative to the use of the traditional intensity binary format NRZ (Non-return-to-zero). Those formats, classified as advanced, represent one of the key technologies aimed to enable the high data volume and broadband, demanded by the present telecommunication market, with cost reduction of tran
Publicado em: 2009
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18. Fault detection in communication systems / Detecção de falhas em sistemas de comunicações
The present work is focused in the area of fault detection in communications systems using billing tickets archives as base of information. In most of the cases, these archives are used by the telecommunication carriers only for billing purposes. The thesis presents algorithms for fault detection and consequence alarms generation. The algorithms are analyzed
Publicado em: 2008
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19. Algoritmos heuristicos em separação cega de fontes / Heuristic algorithms applied to blind source separation
Esta dissertação se propõe a estudar um novo método para separação cega de fontes baseado no modelo Post-Nonlinear, que une uma ferramenta de busca global baseada em computação bioinspirada a uma etapa de busca local conduzida pelo algoritmo FastICA. A idéia subjacente à proposta é procurar obter soluções precisas e eficientes usando de maneira
Publicado em: 2008
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20. Criptografia quântica em redes de informação crítica - aplicação a telecomunicações aeronáuticas. / Quantum cryptography in critical information networks - application to aeronautical telecommunications.
The importance of security maintenance in critical information networks has been rising in recent times. Over the past decades, the utilization of cryptography tools, mainly those based on computationally intractable problems, was enough to ensure the security of communications systems. The development of the new information processing technique known as qua
Publicado em: 2008
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21. Distribuição generalizadas de desvanecimento de curto prazo : medições de campo e validações / Generalized short term fading distributions : field measurements and validations
This thesis provides a thorough comparison among the various short term fading distributions, which are handled so as to give their best fit over data obtained from field measurements. Such distributions include those already well known in the literature - namely Rayleigh, Rice, Nakagami, Hoyt e Weibull - as well as two recently proposed models, namely k-µ
Publicado em: 2008
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22. Performance analysis of video transmission in IEEE 802.11 networks aimed at structuring the return channel digital TV / Analise de desempenho de transmissão de video em redes IEEE 802.11 visando a estruturação de canais de retorno para TV digital
A transmissão de vídeo em redes Wireless é abordada pela pesquisa, devido o grande aumento na utilização dessas redes na ultima década. O acesso à banda larga por essas redes é feito de forma eficiente, rápida e com baixo custo de implementação e manutenção da rede. A motivação para o desenvolvimento é utilizar essas redes e a rede IPTV para
Publicado em: 2008
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23. Análise comparativa de avaliação em press releases e notícias
This dissertation aims at analyzing evaluation in the business language. Evaluation is an aspect of language related to interaction, being a field of studies that may bring a significant contribution to business since companies are entities that depend on communication systems to construct alliances both between their internal elements and with external indi
Publicado em: 2008
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24. Uma avaliação experimental e numérica do efeito da rigidez geométrica na resposta dinâmica de estruturas esbeltas sujeitas à excitação de vento. / An experimental and numerical evaluation of the geometric stiffness effect on the dynamic response of slender structures under wind excitation.
Due to a politically and economically pragmatic decision, Brazil has chosen to intensely develop its cellular phone system, in order to bypass a stage of development. Once the decision has been taken, implementation was set in an explosive pace in the 1990s decade by installing tens of thousands of stations. As the electronic systems are usually more expensi
Publicado em: 2008