1000 resultados para Medição elétrica
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As tecnologias wireless vêm evoluindo de forma rápida nas últimas décadas, pois são uma eficiente alternativa para transmissão de informações, sejam dados, voz, vídeos e demais serviços de rede. O conhecimento do processo de propagação dessas informações em diferentes ambientes é um fator de grande importância para o planejamento e o desenvolvimento de sistemas de comunicações sem fio. Devido ao rápido avanço e popularização dessas redes, os serviços oferecidos tornaram-se mais complexos e com isso, necessitam de requisitos de qualidades para que sejam ofertados ao usuário final de forma satisfatória. Devido a isso, torna-se necessário aos projetistas desses sistemas, uma metodologia que ofereça uma melhor avaliação do ambiente indoor. Essa avaliação é feita através da análise da área de cobertura e do comportamento das métricas de serviços multimídia em qualquer posição do ambiente que está recebendo o serviço. O trabalho desenvolvido nessa dissertação objetiva avaliar uma metodologia para a predição de métricas de qualidade de experiência. Para isso, foram realizadas campanhas de medições de transmissões de vídeo em uma rede sem fio e foram avaliados alguns parâmetros da rede (jitter de pacotes/frames, perda de pacotes/frames) e alguns parâmetros de qualidade de experiência (PSNR, SSIM e VQM). Os resultados apresentaram boa concordância com os modelos da literatura e com as medições.
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The proposed of scanning of an electrical industrial substation HV is associated with a segment of the Electrotechnical area and aims the study and preliminary application of digital technologies in the protection, control, measurement and automation maneuvers aimed at a Industrial Electrical System typical High Voltage. Well intended to supervision, protection and control of major electrical and thermal quantities involved in a substation, such as voltage levels, current, temperature, power factor, loads of transformers and circuit feeders, status of interlocking devices, switching equipment maneuvers, etc
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Pós-graduação em Engenharia Elétrica - FEIS
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Pós-graduação em Engenharia Elétrica - FEIS
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Depuis que l'électricité a été découverte et que le secteur électrique s'est considérablement développé dans le XVIIIe siècle, jamais l'homme n'a pu se détacher de cette énergie. Pendant longtemps le système d'énergie électrique a fonctionné sans grand changement, mais avec le développement rapide des technologies, de nouvelles améliorations apparaissent. Ce mémoire traite des nouveaux concepts de réseaux d'énergie électrique appelés Réseaux intelligents ou Smart Grid. À travers un panorama de leurs développements dans le monde, cette étude porte d'une part, sur l'avancée des projets dans quelques pays et d'autre part, du niveau de développement de ce réseau au Brésil et de son intérêt pour le pays. L'étude a comme point central un des composants de ce réseau intelligent, le compteur communicant, qui est l'élément essentiel des interconnexions entre consommateurs et producteurs. Ce rapport apporte un éclaircissement sur les compteurs conventionnels et les compteurs intelligents et sur leur mode de fonctionnement. Enfin il aborde la question des consommateurs : par quels moyens leur transmettre tous ces changements à venir, puisque jusqu'à présent, leur seule participation était de payer l'énergie consommée. Avec le nouveau réseau, ils deviendront de véritables acteurs puisqu'ils seront informés en temps réel de leur consommation d'énergie électrique. Pour terminer, le mémoire montrera comment ils pourront s'adapter à cette nouvelle façon de gérer leur consommation en ésperant les inciter à une utilisation plus raisonnable de l'énergie et à modifier leur comportement en gérant de manière active leur consommation en intégrant notamment les énergies renouvelables
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Depuis que l'électricité a été découverte et que le secteur électrique s'est considérablement développé dans le XVIIIe siècle, jamais l'homme n'a pu se détacher de cette énergie. Pendant longtemps le système d'énergie électrique a fonctionné sans grand changement, mais avec le développement rapide des technologies, de nouvelles améliorations apparaissent. Ce mémoire traite des nouveaux concepts de réseaux d'énergie électrique appelés Réseaux intelligents ou Smart Grid. À travers un panorama de leurs développements dans le monde, cette étude porte d'une part, sur l'avancée des projets dans quelques pays et d'autre part, du niveau de développement de ce réseau au Brésil et de son intérêt pour le pays. L'étude a comme point central un des composants de ce réseau intelligent, le compteur communicant, qui est l'élément essentiel des interconnexions entre consommateurs et producteurs. Ce rapport apporte un éclaircissement sur les compteurs conventionnels et les compteurs intelligents et sur leur mode de fonctionnement. Enfin il aborde la question des consommateurs : par quels moyens leur transmettre tous ces changements à venir, puisque jusqu'à présent, leur seule participation était de payer l'énergie consommée. Avec le nouveau réseau, ils deviendront de véritables acteurs puisqu'ils seront informés en temps réel de leur consommation d'énergie électrique. Pour terminer, le mémoire montrera comment ils pourront s'adapter à cette nouvelle façon de gérer leur consommation en ésperant les inciter à une utilisation plus raisonnable de l'énergie et à modifier leur comportement en gérant de manière active leur consommation en intégrant notamment les énergies renouvelables
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This study aims to evaluate the uncertainty associated with measurements made by aneroid sphygmomanometer, neonatal electronic balance and electrocautery. Therefore, were performing repeatability tests on all devices for the subsequent execution of normality tests using Shapiro-Wilk; identification of influencing factors that affect the measurement result of each measurement; proposition of mathematical models to calculate the measurement uncertainty associated with measuring evaluated for all equipament and calibration for neonatal electronic balance; evaluation of the measurement uncertainty; and development of a computer program in Java language to systematize the calibration uncertainty of estimates and measurement uncertainty. It was proposed and carried out 23 factorial design for aneroid sphygmomanometer order to investigate the effect of temperature factors, patient and operator and another 32 planning for electrocautery, where it investigated the effects of temperature factors and output electrical power. The expanded uncertainty associated with the measurement of blood pressure significantly reduced the extent of the patient classification tracks. In turn, the expanded uncertainty associated with the mass measurement with neonatal balance indicated a variation of about 1% in the dosage of medication to neonates. Analysis of variance (ANOVA) and the Turkey test indicated significant and indirectly proportional effects of temperature factor in cutting power values and clotting indicated by electrocautery and no significant effect of factors investigated for aneroid sphygmomanometer.
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This work presents a low cost architecture for development of synchronized phasor measurement units (PMU). The device is intended to be connected in the low voltage grid, which allows the monitoring of transmission and distribution networks. Developments of this project include a complete PMU, with instrumentation module for use in low voltage network, GPS module to provide the sync signal and time stamp for the measures, processing unit with the acquisition system, phasor estimation and formatting data according to the standard and finally, communication module for data transmission. For the development and evaluation of the performance of this PMU, it was developed a set of applications in LabVIEW environment with specific features that let analyze the behavior of the measures and identify the sources of error of the PMU, as well as to apply all the tests proposed by the standard. The first application, useful for the development of instrumentation, consists of a function generator integrated with an oscilloscope, which allows the generation and acquisition of signals synchronously, in addition to the handling of samples. The second and main, is the test platform, with capabality of generating all tests provided by the synchronized phasor measurement standard IEEE C37.118.1, allowing store data or make the analysis of the measurements in real time. Finally, a third application was developed to evaluate the results of the tests and generate calibration curves to adjust the PMU. The results include all the tests proposed by synchrophasors standard and an additional test that evaluates the impact of noise. Moreover, through two prototypes connected to the electrical installation of consumers in same distribution circuit, it was obtained monitoring records that allowed the identification of loads in consumer and power quality analysis, beyond the event detection at the distribution and transmission levels.
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Dissertação (mestrado)— Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Elétrica, 2015.
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Background: In pathological situations, such as acute myocardial infarction, disorders of motility of the proximal gut can trigger symptoms like nausea and vomiting. Acute myocardial infarction delays gastric emptying (GE) of liquid in rats. Objective: Investigate the involvement of the vagus nerve, α 1-adrenoceptors, central nervous system GABAB receptors and also participation of paraventricular nucleus (PVN) of the hypothalamus in GE and gastric compliance (GC) in infarcted rats. Methods: Wistar rats, N = 8-15 in each group, were divided as INF group and sham (SH) group and subdivided. The infarction was performed through ligation of the left anterior descending coronary artery. GC was estimated with pressure-volume curves. Vagotomy was performed by sectioning the dorsal and ventral branches. To verify the action of GABAB receptors, baclofen was injected via icv (intracerebroventricular). Intravenous prazosin was used to produce chemical sympathectomy. The lesion in the PVN of the hypothalamus was performed using a 1mA/10s electrical current and GE was determined by measuring the percentage of gastric retention (% GR) of a saline meal. Results: No significant differences were observed regarding GC between groups; vagotomy significantly reduced % GR in INF group; icv treatment with baclofen significantly reduced %GR. GABAB receptors were not conclusively involved in delaying GE; intravenous treatment with prazosin significantly reduced GR% in INF group. PVN lesion abolished the effect of myocardial infarction on GE. Conclusion: Gastric emptying of liquids induced through acute myocardial infarction in rats showed the involvement of the vagus nerve, alpha1- adrenergic receptors and PVN.Fundamento: Distúrbios da motilidade do intestino proximal no infarto agudo do miocárdio podem desencadear sintomas digestivos como náuseas e vômitos. O infarto do miocárdio ocasiona retardo do esvaziamento gástrico (EG) de líquido em ratos. Objetivo: Investigar se existe a influência do nervo vago (VGX), adrenoreceptores α-1, receptores GABAB do sistema nervoso central e participação do núcleo paraventricular (NPV) do hipotálamo no esvaziamento gástrico (EG) e complacência gástrica (CG) em ratos infartados. Métodos: Ratos Wistar (n = 8-15) foram divididos em: grupo infarto (INF), sham (SH) e subdivididos. O infarto foi realizado por ligadura da artéria coronária descendente anterior. A complacência gástrica foi estimada com curvas pressão-volume. Realizada vagotomia por secção dos ramos dorsal e ventral. Para verificar a ação dos receptores GABAB foi injetado baclofeno por via intra ventrículo-cerebral. Simpatectomia química foi realizada com prazosina intravenosa (iv), e na lesão do núcleo paraventricular do hipotálamo foi utilizada corrente elétrica de 1mA/10s, com esvaziamento gástrico determinado por medição da retenção gástrica (% RG) de uma refeição salina. Resultados: Não houve diferença significativa na CG. A vagotomia (VGX) reduziu significativamente a %RG; no grupo INF, o tratamento intra ventrículo-cerebral (ivc) com baclofeno reduziu significativamente a % RG; não houve conclusivamente envolvimento dos receptores GABAB em retardar o EG; o tratamento intravenoso com prazosina reduziu significativamente a %RG no grupo INF. A lesão do NPV aboliu o efeito do infarto do miocárdio no EG. Conclusão: O nervo vago, receptores α-adrenérgicos e núcleo paraventricular estão envolvidos no retardo do esvaziamento gástrico no infarto agudo do miocárdio em ratos.
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An alternative proposal for floor heating system by means of electric resistance for both chick and piggy installation is presented in this work. Several formulations of rice husk and cement mortar boards were used. An electronic device controlled all board temperature. This system presented a good efficiency design. The conventional cement mortar mixed with rice husk showed a better performance.
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Twenty-two Triceps brachii muscle obtained from 11 cows aged 3 and 4 years , killed in an experimental slaughter plant, were submitted to mechanical tenderization, injection with acetic acid 0,1M and lactic acid 0,2M, ageing for 9 and 14 days and electrical stimulation (250v - 60Hz - 90s), some of them were reserved as a control group, without treatment. The 14 days ageing time presented 21% of increase in subjective tenderness and 12% of reduction in shear force, these values were similar to the electrical stimulated meat. However the injection with acids and the ageing time 9 days did not present significant effect in the texture. Although the shear force values of mechanical tenderized meat was the shortest among all treatments, suspect of superestimation because of the fractures plan created by this process. Another analyses were carried out: pH reduction curve, R value; colour analysis; weight losses by cooking and by treatment; and microbiological analysis.
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Universidade Estadual de Campinas. Faculdade de Educação Física