917 resultados para wireless communication technology
Resumo:
Este trabalho faz uma análise de desempenho de aplicações triple play através da tecnologia Power Line Communication, fazendo uma abordagem direcionada para qualidade de serviço e qualidade de experiência. Apresenta resultados obtidos em cenários residenciais onde o uso desta tecnologia como última milha mostra-se uma solução passível de implementação diante dos testes realizados com transmissões de chamadas VoIP, transmissões de vídeo em alta definição e dados. O conceito de rede doméstica, interligando todos os pontos de uma casa, vem representando um novo rumo na definição de um padrão global, no qual a transmissão de dados por meio da fiação elétrica será uma das tecnologias empregadas e de maior destaque. Também será mostrado o desempenho das métricas avaliadas como jitter, largura de banda, perda de pacotes, PSNR, MOS, VQM, SSIM e suas correlações.
Resumo:
Esta dissertação tem como objetivo principal propor um nodo (ou nó) sensor sem fio para ser utilizado em redes de sensores sem fio, em sistemas de aquisição de dados de extensômetros. O sistema de aquisição para os extensômetros é baseado na ponte de Wheatstone e de modo a permitir várias configurações de extensômetros. O processamento e a comunicação sem fio é realizada pelo ATmega128RFA1, composto por um microcontrolador e um transceiver Rádio-Frequência com o padrão Zigbee. O nodo foi projetado para garantir confiabilidade na aquisição de dados e ser totalmente controlado remotamente. Entre os parâmetros controláveis estão: o ganho do sinal e a taxa de amostragem. Além disso, o nodo possui recursos para efetuar o equilíbrio da ponte de Wheatstone automaticamente. A escolha de seus componentes, baseou-se em critérios relacionados ao consumo de energia do mesmo e ao custo. Foi concebida uma placa de circuito impresso (PCI) para o nodo, e sobre ela foram realizadas estimativas sobre o consumo de energia e valor agregado do protótipo, com o objetivo de analisar a sua viabilidade. Além do projeto do nodo sensor, o trabalho apresenta a proposta de integração do mesmo em uma rede de sensores sem fio (RSSF), incluindo a sugestão do hardware complementar e desenvolvimentos dos softwares. Para os testes do nodo sensor, foi construido experimentalmente um transdutor de força.
Resumo:
O avanço nas áreas de comunicação sem fio e microeletrônica permite o desenvolvimento de equipamentos micro sensores com capacidade de monitorar grandes regiões. Formadas por milhares de nós sensores, trabalhando de forma colaborativa, as Redes de Sensores sem Fio apresentam severas restrições de energia, devido à capacidade limitada das baterias dos nós que compõem a rede. O consumo de energia pode ser minimizado, permitindo que apenas alguns nós especiais, chamados de Cluster Head, sejam responsáveis por receber os dados dos nós que formam seu cluster e propagar estes dados para um ponto de coleta denominado Estação Base. A escolha do Cluster Head ideal influencia no aumento do período de estabilidade da rede, maximizando seu tempo de vida útil. A proposta, apresentada nesta dissertação, utiliza Lógica Fuzzy e algoritmo k-means com base em informações centralizadas na Estação Base para eleição do Cluster Head ideal em Redes de Sensores sem Fio heterogêneas. Os critérios usados para seleção do Cluster Head são baseados na centralidade do nó, nível de energia e proximidade para a Estação Base. Esta dissertação apresenta as desvantagens de utilização de informações locais para eleição do líder do cluster e a importância do tratamento discriminatório sobre as discrepâncias energéticas dos nós que formam a rede. Esta proposta é comparada com os algoritmos Low Energy Adaptative Clustering Hierarchy (LEACH) e Distributed energy-efficient clustering algorithm for heterogeneous Wireless sensor networks (DEEC). Esta comparação é feita, utilizando o final do período de estabilidade, como também, o tempo de vida útil da rede.
Resumo:
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Resumo:
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Resumo:
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Resumo:
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Resumo:
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Resumo:
Cognitive radio is a growing zone in wireless communication which offers an opening in complete utilization of incompetently used frequency spectrum: deprived of crafting interference for the primary (authorized) user, the secondary user is indorsed to use the frequency band. Though, scheming a model with the least interference produced by the secondary user for primary user is a perplexing job. In this study we proposed a transmission model based on error correcting codes dealing with a countable number of pairs of primary and secondary users. However, we obtain an effective utilization of spectrum by the transmission of the pairs of primary and secondary users' data through the linear codes with different given lengths. Due to the techniques of error correcting codes we developed a number of schemes regarding an appropriate bandwidth distribution in cognitive radio.
Resumo:
Speech has been regarded as a social communicative modality required for building relationships in different contexts and cultures. Nevertheless, this is not always a readily available resource, especially for those who have developmental disorders. In this sense, Augmentative and Alternative Communication resources and strategies have been used by nonspeaking students with disabilities as useful tools to achieve greater social participation in different environments. Therefore, the present study examined the interaction between teachers and a student with cerebral palsy before and after the use of Alternative Communication strategies in the classroom. The study had a quantitative and qualitative nature and was designed as an intervention study. There were four main stages: 1) filming before the introduction of the resources in the classroom, 2) training the school teachers 3) providing technical assistance regarding the use of alternative communication to the child's teacher 4) filming teacher-student interactions using these technological resources. The interactions were transcribed and grouped into links. In this research, a link means the initiator's behavior directed to the exchange partner and the response in sequence from the interlocutor back to the initiator. It was found that the established interactions presented a maximum of four links, with greater frequency for episodes of 1st and 2nd links. After the intervention, there were different contexts with the presence of interactions up to the 6th link, often greater frequency for episodes of 1st, 2nd and 3rd links. In addition, the teacher showed a tendency to use symbols only as a tool for evaluating and teaching concepts. This perception changed as the teacher became familiarized with the Augmentative and Alternative Communication technology resources.
Resumo:
In recent decades the rise of the tools of information and communication technology (ICT) has been notorious. Currently ICTs are an important educational tool and is associated with the development of teaching methods courses in basic and higher education. Given the influence that these tools are currently engaged in several sectors, this project aimed to assess the frequency and manifestations of ICT that have been employed in the teaching of histology in the Schools of Dentistry of São Paulo. The virtual page of 43 Higher Education Institutions (HEI) was analyzed to search for links to sites of histology. With this assessment only 4 virtual domains were found which was present a narrow range of virtual tools such as hypertext, graphics, quizzes and lessons in electronic formats. Later, by sending a questionnaire to 46 teachers of histology of the Universities of São Paulo, were analyzed for the presence or absence of a site of discipline, mode and frequency of use of ICTs in education, and the value that teacher attaches to these tools. From the responses obtained were concluded that teachers who have websites in general have no interactivite tools and many seem to ignore the real representation of interactivity in teaching and the possibilities of applications of ICTs. However most teachers recognize the importance of education mediated by virtual tools
Resumo:
This work has by main objective revisit the dichotomy speech/writing from the perspective of scholars in the field of linguistics in relation to the communicative and interactional aspects of language. The research is based on the study of traditional dichotomies that classically distinguish between the oral form and the written form of the language. It is noted here the importance of the study of communication and interaction of individuals, as language being the main aspect responsible for the organization of society, and, of course, also being indispensable for the development of human being. This study shows that the distinctive peculiarities between speech and writing are not of the characteristics of a particular procedure, but differences that are necessary due to the specific moment of creation of an utterance or text, because both the oral and the mode writing may have traces of formality/informality; completeness/incompleteness, among other things. In other words, there is not a distinctive feature that is present only in speech or writing. Thus, this research shows that, by the numberless technological advances, the communication between people has gone through changes and crossed barriers. Therefore, it is clear that with the collaboration of the media, the old dichotomies recommended for speech and writing are being overcome and can no longer be treated strictly to any of the modalities
Resumo:
Due to the need of more agility, dynamism and reliability in stock management, the market has turned its attention to RFID, which offers a practical solution and live up to the big corporations' expectations. The search for continuous improvement establishes a direct link with RFID, for its technology offers accurate real time information in any monitored given place. RFID is a radio frequency communication technology. A reader communicates to a tag through waves. This tag can be active, with a battery, or passive, in which its power is supplied by currents induced by the field variation it is exposed to. The RFID technology has a well defined basic principle, but there are many constructive ways of implementing it. The adaptability as well as the flexibility regard to the several kinds of stock in industry, reaching their particular needs. RFID can lower maintenance costs in stock by collecting data more accurately, lowering human error and optimizing the item handling at its reception, exit and while it is inside the company. This paper presents an example of RFID technology applied in a company's stock management. It is possible to prove that there are, in fact, great advantages in implementing this technology, as it creates the opportunity for continuous improvement in stock management, with better application of material, labour and quality tools, since the data collected through an automatized process using RFID are more reliable and dynamic
Resumo:
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Resumo:
Pós-graduação em Engenharia Elétrica - FEIS