876 resultados para Sistemas de comunicação móvel - Comercialização


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Nos últimos anos, com o surgimento de novos serviços e equipamentos para o sistema de comunicação móvel com maiores larguras de banda de operação e ocupando espaços cada vez menores, o desenvolvimento de novas antenas de bandas largas e com dimensões pequenas se tornou um dos principais desafios das pesquisas na área de antenas. Neste trabalho, duas estruturas de antenas de bandas largas e dimensões reduzidas foram analisadas e otimizadas. Na primeira parte, a antena filamentar monopolo dobrado (Wire Built-in Folded Monopole Antenna, W-BFMA) foi investigada e teve sua largura de banda otimizada, conectada a linha de alimentação em diferentes impedâncias. Para modelar a estrutura da antena W-BFMA foi usado o método numérico dos momentos (Method of Moments - MoM), e para sua otimização os métodos: paramétrico, hill climbing e algoritmo genético (AG). Programas computacionais baseados na linguagem Matlab foram desenvolvidos para modelagem, otimização e cálculos das principais curvas características da antena W-BFMA. Na segunda parte, duas diferentes configurações de antenas monopolos planos usando a tecnologia de banda ultra-larga (Ultra- Wideband Antenna, UWB) foram investigadas e otimizadas com a ajuda do programa comercial Computer Simulation Technology (CST) Microwave Studio. Ambas as antenas UWB foram alimentadas por uma linha de microfita (microstrip line) na impedância de 50Ω. A antena UWB que apresentou melhor resultado teve o seu protótipo construído, as principais curvas características, tais como: perda de retorno, ganho, distribuição de corrente e diagrama de radiação foram analisadas. Os resultados simulados foram comparados com resultados obtidos experimentalmente.

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Esta dissertação tem como objetivo principal apresentar a implementação de um software-modem ADSL totalmente escrito em Java, utilizando o framework Ptolemy II, denominado de Hermes (de "A Handy Experimental Software Modem System"). Um software-modem é útil em ocasiões onde se precisem executar testes e simulações de sistemas de comunicação com um número grande de modens e quando os parâmetros desses sistemas precisem ser modificados com um alto grau de liberdade. Além disso, um software-modem possui características que tornam mais fácil a tarefa de acrescentar, eliminar, validar e analisar funções e algoritmos de processamento de sinais e de telecomunicações. Testes e simulações foram realizados para analisar a funcionalidade do Hermes, utilizando, inclusive, o Tracespan, um equipamento para análise não-intrusiva de redes DSL. A partir dos resultados obtidos em conjunto com o Tracespan, foi possível validar com sucesso as funções do Hermes.

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Este trabalho teve como proposta realizar pesquisa das tecnologias existentes para telefonia e integração das mesmas para concepção de um sistema inovador e projetado para a realidade Amazônida. O trabalho incluiu avaliar a implementação de um sistema GSM open source / open hardware de custo zero para a população (telefonia celular gratuita) em comunidades rurais na Amazônia, com enfoque nas comunidades isoladas e carentes onde geralmente não há cobertura celular de operadoras comerciais, devido a falta de estímulo do governo e/ou interesse comercial de prover telefonia para essas populações mais pobres.

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Pós-graduação em Desenvolvimento Humano e Tecnologias - IBRC

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Researchers in the field of Augmentative and Alternative Communication point out the lack of instruments for assessing children and young people with a complex communication needs. This study's focus is the selection of words for creating an instrument for the vocabulary range in non-speaking children aged two to eleven years and eleven months. Three studies were performed. The first study identified and described tools available for assessing receptive vocabulary and their respective word lists. The second identified and described research that presented word inventories or word lists. The third study identified the vocabulary reported by parents and teachers. The words that were identified in the three studies were analyzed according to: the number of times they occurred; the Picture Communication Symbols system classification; and a semantic and syntactic classification. Based on these studies the following criteria for vocabulary selection were established for word selection: the 45 words which appeared in all three studies, the words that occurred five times or more, considering the three studies, representing 167 (14.14%) words; the words identified in study one or two, but that had been reported by the families - 183 (19.37% out of 945 words) - or by teachers - 108 (11.43% out of 945 words). The word list was composed of 269 items, classified in 18 semantic and syntactic topics; it represents an initial tool for professionals in the field of health and education to set goals for beginning assessment of children and teenagers who are users of Augmentative and Alternative Communication systems.

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Pós-graduação em Engenharia Elétrica - FEIS

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This final paper is a reflection on mobile service of urgency by raising the main difficulties encountered by organizations, and seeking innovative solutions through new technological features like smartphones, tablets application and cloud computing to develop a scalable system and globalized, based on geolocation that is able to overcome this difficulty being accessible to the whole population

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Smart grids are the focus of major study today because of the necessity of modernization in electrical systems and reduction of greenhouse gas emissions that increases global warming. Reaching the best deployment method, you must first of all know the current electrical system and how to use them for the benefit of this new technology. Preparing the action plan we should be aware of the main points of smart grids in each step of the electricity system - generation, transmission and distribution. Analyzed these topics, this work will focus on the first step in the implementation of the smart grids: the smart meters, tool which is already being implemented in Brazil. The main characteristics and applications of these devices, as well as their communication structure with the core distributors will be showed during the paper. Finally, we present a case study which will be discussed and analyzed based in the results obtained with the implementation of smart meters in the city of Vancouver, Canada, where we have a considerable savings already in the first year, with fully paying the initial investment and still have a profit

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Changes are occurring worldwide, including the area of positioning using Global Navigation Satellite Systems in mobile devices such as mobile phones or laptops. This is due to the great improvement and availability of Internet services to these mobile devices. The accuracy and speed of data transmission for these devices makes the technology of sending / receiving data via an internet targeted for optimization. The optimization could allow obtaining, in real-time, coordinates (latitude, longitude and altitude) of suitable quality for users of GPS (Global Positioning System) devices that have wireless Internet access, such as those used to control the eet, locomotion, navigation, agriculture, etc. . The use of the protocol NTRIP (Networked Transport of RTCM via Internet Protocol) in GPS applications is growing every day. Applications are available in C, which creates an opportunity for development with a focus on multiplatform environments. In this context, we propose an application, implemented in a multiplatform environment and the use of NTRIP, able to run on a mobile device for receiving GNSS data

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Pós-graduação em Engenharia Mecânica - FEG

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This paper presents a design and construct the system of data acquisition with wireless transmission of some important parameters like motor temperature, motor rotation and velocity of Unesp Racing´s formula car prototype from Universidade Estadual Paulista, Campus Guaratinguetá. This system development presents a contribution for the electrical technical features adding important points in the competition due car´s electric, in addition, enables preventive maintenance and fine adjustment of the car with the data obtained during training and racing

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Pós-graduação em Engenharia Elétrica - FEIS

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Didactic texts compose communication and representation systems. By them societies communicate with their children, their youth, transmit them live representations, symbols, ways of understanding speeches and delimit their study fields. This article presents a discussion about the medias used by Portuguese language text books selected by the Ministry of Education Textbook National Program (PNDL – in Portuguese), in order to observe the foundation of actions, movements and media insertion at school. The analysis allows us to see the consolidation of an individualist profile among the strategies of using medias at school, among others aspects.