962 resultados para Digital to Analog Converter
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This article attempts to analyze the definition of "electronic literature" as given by the Electronic Literature Organization and to understand the relationship between electronic literature and digital literature. The thesis defended here is that this change of adjective hides a change in the theoretical status of the object that it attempts to define. The definition of electronic literature once concentrated on the tools used in the production of literary works and the critical analysis concentrating on the objects produced with the aid of new technologies. The move to the adjective "digital" marks a change in perception: now, from this perspective, the challenge is no longer to study works produced thanks to computers, but to understand the new status of literature in the age of the digital. To demonstrate this thesis, the article proposes to analyze one recent literary example: the 1984 trilogy by Eric Plamondon.
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Nossa intenção, na presente investigação é seguir um procedimento analógico ao da construção da competência leitora e refletir sobre as influências educacionais, sobretudo, no interesse, ou falta dele, pela leitura, competência fundamental para o desenvolvimento do indivíduo na sociedade. Iniciamos pelo processo de aprendizagem e ensino da leitura e finalizamos com as reflexões: como a prática pedagógica do docente, desperta ou reconcilia o jovem leitor com a leitura? Compreendemos que somos capazes de contribuir para o desenvolvimento e aprofundamento dos hábitos de leitura dos estudantes, principalmente escolar, a fim de “aprimorar” os níveis de leitura e promover no estudante o prazer de ler, desde que, nós enquanto figuras mediadoras e motivadoras em sala de aula, o professor, sintam verdadeiramente esse desejo de desperta no outro o prazer de ler. Como resultado, depreende-se que o próprio professor ainda não incorporou seu papel enquanto figura motivadora, importantíssima, na construção de alunos leitores. Simultaneamente constatamos que o professor é sabedor das lacunas no seu processo de formação acadêmica e da necessidade de formação continuada para “aperfeiçoamento” da sua prática e da posição que ocupam como sujeitos de suas leituras e que seu hábito de leitura, ou ausência dele, tem consequência na prática de ensino/aprendizagem e em seu posicionamento frente aos estudantes como ícone motivador da mesma. Concomitantemente, aferimos que a concepção que predomina nas práticas da leitura ainda é a noção de leitura como decodificação de palavras, essa percepção é notada não só na fala dos estudantes, mas também na do professor. Aferimos também, que a maioria dos estudantes investigados não tem o hábito da leitura e consequentemente não tem consciência das estratégias usadas nesse processo de produção de significados. Esperamos que as discussões aqui apresentadas, e os resultados obtidos nesta investigação proporcionem reflexões sobre a prática pedagógica, favorecendo alterações que colaborem para a melhoria do ensino/aprendizagem de leitura.
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Currently, there are several power converter topologies applied to wind power generation. The converters allow the use of wind turbines operating at variable speed, enabling better use of wind forces. The high performance of the converters is being increasingly demanded, mainly because of the increase in the power generation capacity by wind turbines, which gave rise to various converter topologies, such as parallel or multilevel converters. The use of converters allow effective control of the power injected into the grid, either partially, for the case using partial converter, or total control for the case of using full converter. The back-to-back converter is one of the most used topologies in the market today, due to its simple structure, with few components, contributing to robust and reliable performance. In this work, is presented the implementation of a wind cogeneration system using a permanent magnet synchronous generator (PMSG) associated with a back-to-back power converter is proposed, in order to inject active power in an electric power system. The control strategy of the active power delivered to the grid by cogeneration is based on the philosophy of indirect control
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A detector system that can measure X-ray intensity in the mammographic range of 22 to 36 kVp (equivalent photon energies ofthe beam between 11 and 15 keV) is presented. It consists of a lithium mobate detector and a high-sensitivity current-to-voltage converter.
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This paper presents the development and experimental analysis of a special input stage converter for a Trolleybus type vehicle allowing its operation in AC (two wires, single-phase) or DC distribution networks. The architecture of proposed input stage converter is composed by five interleaved boost rectifiers operating in discontinuous conduction mode. Furthermore, due to the power lines characteristics, the proposed input power structure can act as AC to DC or as DC to DC converter providing a proper DC output voltage range required to the DC bus. When operation is AC to DC, the converter is capable to provide high power factor with reduced harmonic distortion for the input current, complying with the restrictions imposed by IEC 61000-3-4 standard. Finally, the main experimental results are presented in order to verify the feasibility of the proposed converter, demonstrating the benefits and the possibility for AC feeding system for trolleybus type vehicle. © 2010 IEEE.
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Networked control systems (NCS) are distributed control system in which sensors, actuators and controllers are physically separated and connected through communication networks. NCS represent the evolution of networked control architectures providing greater modularity and control decentralization, ease maintenance and diagnosis and lower cost of implementation. A recent trend in this research topic is the development of NCS using wireless networks which enable interoperability between existing wired and wireless systems. This paper presents the feasibility analysis of using a serial RS-232 to Bluetooth converter as a wireless sensor link in NCS. In order to support this investigation, relevant performance metrics for wireless control applications such as jitter, time delay and messages lost are highlighted and calculated to evaluate the converter capabilities. In addition the control performance of an implemented motor control system using the converter is analyzed. Experimental results led to the conclusion that serial RS-232 Bluetooth converters can be used to implement wireless networked control systems (WNCS) providing transmission rates and closed control loop times which are acceptable for NCS applications. © 2011 IEEE.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Sistemas de reconhecimento e síntese de voz são constituídos por módulos que dependem da língua e, enquanto existem muitos recursos públicos para alguns idiomas (p.e. Inglês e Japonês), os recursos para Português Brasileiro (PB) ainda são escassos. Outro aspecto é que, para um grande número de tarefas, a taxa de erro dos sistemas de reconhecimento de voz atuais ainda é elevada, quando comparada à obtida por seres humanos. Assim, apesar do sucesso das cadeias escondidas de Markov (HMM), é necessária a pesquisa por novos métodos. Este trabalho tem como motivação esses dois fatos e se divide em duas partes. A primeira descreve o desenvolvimento de recursos e ferramentas livres para reconhecimento e síntese de voz em PB, consistindo de bases de dados de áudio e texto, um dicionário fonético, um conversor grafema-fone, um separador silábico e modelos acústico e de linguagem. Todos os recursos construídos encontram-se publicamente disponíveis e, junto com uma interface de programação proposta, têm sido usados para o desenvolvimento de várias novas aplicações em tempo-real, incluindo um módulo de reconhecimento de voz para a suíte de aplicativos para escritório OpenOffice.org. São apresentados testes de desempenho dos sistemas desenvolvidos. Os recursos aqui produzidos e disponibilizados facilitam a adoção da tecnologia de voz para PB por outros grupos de pesquisa, desenvolvedores e pela indústria. A segunda parte do trabalho apresenta um novo método para reavaliar (rescoring) o resultado do reconhecimento baseado em HMMs, o qual é organizado em uma estrutura de dados do tipo lattice. Mais especificamente, o sistema utiliza classificadores discriminativos que buscam diminuir a confusão entre pares de fones. Para cada um desses problemas binários, são usadas técnicas de seleção automática de parâmetros para escolher a representaçãao paramétrica mais adequada para o problema em questão.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Networked control systems (NCSs) are distributed control system in which sensors, actuators and controllers are physically separated and connected through communication networks. NCS represent the evolution of networked control architectures providing greater modularity and control decentralization, ease maintenance and diagnosis and lower cost of implementation. A recent trend in this research topic is the development of NCS using wireless networks(WNCS)which enable interoperability between existing wiredand wireless systems. This paper presents the feasibility analysis of using serial to wireless converter as a wireless sensor link in NCS. In order to support this investigation, relevant performance metrics for wireless control applications such as jitter, time delay and messages lost are highlighted and calculated to evaluate the wireless converter capabilities. In addition the control performance of an implemented motor control system using the converter is analyzed. Experimental results led to the conclusion that serial ZigBee device isrecommended against the Bluetooth as it provided better metrics for control applications. However, bothdevices can be used to implement WNCS providing transmission rates and closed control loop times which are acceptable for NCS applications.Moreoverthe use of thewireless device delay in the PID controller discretization can improve the control performance of the system.
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This paper describes the development of an Advanced Speech Communication System for Deaf People and its field evaluation in a real application domain: the renewal of Driver’s License. The system is composed of two modules. The first one is a Spanish into Spanish Sign Language (LSE: Lengua de Signos Española) translation module made up of a speech recognizer, a natural language translator (for converting a word sequence into a sequence of signs), and a 3D avatar animation module (for playing back the signs). The second module is a Spoken Spanish generator from sign-writing composed of a visual interface (for specifying a sequence of signs), a language translator (for generating the sequence of words in Spanish), and finally, a text to speech converter. For language translation, the system integrates three technologies: an example-based strategy, a rule-based translation method and a statistical translator. This paper also includes a detailed description of the evaluation carried out in the Local Traffic Office in the city of Toledo (Spain) involving real government employees and deaf people. This evaluation includes objective measurements from the system and subjective information from questionnaires. Finally, the paper reports an analysis of the main problems and a discussion about possible solutions.
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This paper presents the SAILSE Project (Sistema Avanzado de Información en Lengua de Signos Española ? Spanish Sign Language Advanced Information System). This project aims to develop an interactive system for facilitating the communication between a hearing and a deaf person. The first step has been the linguistic study, including a sentence collection, its translation into LSE (Lengua de Signos Española - Spanish Sign Language), and sign generation. After this analysis, the paper describes the interactive system that integrates an avatar to represent the signs, a text to speech converter and several translation technologies. Finally, this paper presents the set up carried out with deaf people and the main conclusions extracted from it.
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A proposal to increase the existing residential LV grid voltage from 230 V has been made in order to increase existing network capacity. A power-electronic AC-AC converter is then used to provide 230 V at each property. Several constraints such as temperature rise at the converter location lead to a converter design requiring very high efficiency. In this paper results from a recent feasibility study in terms of LV network capacity increase are presented along with the design and testing of a SiC based 1 kW, AC/AC prototype module, which forms the basis of a much larger 15 kW multi-module converter.
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A proposal to increase the existing residential LV grid voltage from 230 V to 300 V has been made in order to increase existing network capacity. A power-electronic AC-AC converter is then used to provide 230 V at each property. The equipment can also provide power-quality improvements to the network and load. Several constraints such as temperature rise at the converter location lead to a converter design requiring very high efficiency. In this paper different AC/AC converter topologies are presented which compares the power quality benefits, size and efficiency of each converter. The design and the control technique of the most suitable topology are verified using simulation and preliminary experimentally results of prototype hardware are also included. © 2013 IEEE.