983 resultados para Lamp-chimneys, globes, etc.
Resumo:
Este texto tem como objetivo básico realizar o arriscado exercício de pensar como, no Brasil das últimas décadas, desenvolveram-se o que se irá chamar de "estudos políticos". Tal designação, passível de muitas críticas e desconfianças, é reveladora da grande dificuldade em delinear o campo dos trabalhos cobertos pela reflexão, uma vez que trata-se, fundamentalmente, de situar as questões e relações, ao mesmo tempo competitivas e complementares, de uma produção que, tendo como objeto "temas políticos", pode assumir contornos teórico-metodológicos mais próximos ou distantes da história, da ciência política ou, também, de outras ciências sociais.
Resumo:
Trata dos fatores formadores e influenciadores da Imagem em seus vários aspectos: imagem de produtos, de organizações, de pessoas, etc ... Expõe a relevância do conceito de Imagem no processo de percepção humana, particularmente no contexto da ação mercadológica. Conceitua a Imagem, diferenciando-a de conceitos próximos. Apresenta a Teoria do Comportamento do Consumidor. Discute processos e programas de formação da alteração da Imagem. Relata casos de empresas e pessoas envolvidas em projetos de formação ou alteração da Imagem.
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:
This work has as objective to develop an interesting research line in the Optical Instrumentation area, that is to associate the Optical Design to the Ophthalmology area. The purpose of it is handling the optical design techniques to design a widely used ophthalmologic instrument called slit lamp. The optical and mechanical design of the slit lamp prototype was carefully projected in order to improve the best quality image, the comfort of the patient and the user, the simplicity of handling, the facility of production the availability of optical and mechanical components in the national market and the low cost of production. The main goal of this work was to realize a project using totally national technology, cheapening the cost and forming the optimum image required for the slit lamp optical system.
Resumo:
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Resumo:
An electronic ballast for multiple tubular fluorescent lamp systems is presented. The proposed structure has a high value for the power factor, a dimming capability, and soft switching of the semiconductor devices operated at high frequencies. A zero-current switching pulse width modulated SEPIC converter is used as the rectifying stage and it is controlled using the instantaneous average input current technique. The inverting stage consists of classical resonant half-bridge converter with series-resonant parallel-loaded filters. The dimming control technique is based on varying the switching frequency and monitoring the phase shift of the current drained by the filters and lamps in order to establish a closed loop control. Experimental results are presented that validate the theoretical analysis.
Fluorescent lamp model based on equivalent resistances, considering the effects of dimming operation
Resumo:
This paper presents a new methodology for the determination of fluorescent lamp models based on equivalent resistances. One important feature of the proposed methodology is concerned with the inclusion of the filaments into the model, considering the effects of dimming operation on the equivalent resistances. The classical Series-Resonant Parallel-Loaded Half-Bridge inverter is used as the power stage of the ballast. Moreover, the variation of the inverter's switching frequency is the dimming technique assumed for the analyses. Results obtained with a F32T8 lamp indicate that the accuracy of the model is very satisfactory. Thus, the lamp models obtained with the proposed methodology have the potential to serve as an important tool for ballast designers, considering the necessity for evaluating the lamp/ballast compatibility, according to issues concerned to the operating conditions of the electrodes' filaments.
Resumo:
This paper presents an improved design methodology for determining the parameters used in the classical Series-Parallel Loaded Resonant (SPLR) filter employed in the switching frequency controlled dimmable electronic ballasts. According to the analysis developed in this paper, it is possible to evaluate some characteristics of the resonant filter during the dimming process, such as: range of switching frequency, phase shift and rms value of the current drained by the resonant filter + fluorescent lamp set.
Resumo:
This paper presents an improved design methodology for the determination of the parameters used in the classical series-resonant parallel-loaded (SRPL) filter employed in the switching frequency controlled dimmable electronic ballasts. According to the analysis developed in this paper, it is possible to evaluate some important characteristics of the resonant filter during the dimming operation, such as: range of switching frequency, phase shift, and rms value of the current drained by the resonant filter + fluorescent lamp set. Experimental results are presented in order to validate the analyses developed in this paper. © 2005 IEEE.
Resumo:
This study sought to assess the pulp chamber temperature in different groups of human teeth that had been bleached using hydrogen peroxide gel activated with halogen lamps or hybrid LED/laser appliances. Four groups of ten teeth (maxillary central incisors, mandibular incisors, mandibular canines, and maxillary canines) were used. A digital thermometer with a K-type thermocouple was placed inside pulp chambers that had been filled with thermal paste. A 35% hydrogen peroxide-based red bleaching gel was applied to all teeth and photocured for a total of three minutes and 20 seconds (five activations of 40 seconds each), using light from an LED/laser device and a halogen lamp. The temperatures were gauged every 40 seconds and the data were analyzed by three-way ANOVA, followed by Tukey's test. Regardless of the light source, statistically significant differences were observed between the groups of teeth. The mean temperature values (±SD) were highest for maxillary central incisors and lowest for mandibular canines. The halogen lamp appliance produced more pulp chamber heating than the LED/laser appliance. The increase in irradiation time led to a significant increase in temperature.
Resumo:
Explica las tareas de tipo administrativo específicas de cada unidad: mantención de archivos manuales y computacionales; recepción de correspondencia, material bibliográfico, facturas; solicitud de entrega de documentos, de búsquedas por computador, etc. En anexos, incluye formularios y cartas tipo.