Modelo computacional para dimensionamento de tratores, equipamentos e operações agrícolas

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Rede Neuro-Fuzzy-Wavelet para detecção e classificação de anomalias de tensão em sistemas elétricos de potência

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estudos teóricos e experimentais da operação conjunta de um supressor eletromagnético e de um filtro ativo de potência

Pós-graduação em Engenharia Elétrica - FEIS

Localização de descargas parciais em transformadores de potência imersos em óleo mineral por meio de cápsulas piezelétricas de baixo custo e sistemas inteligentes

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Alocação ótima de equipamentos SVC e TCSC na rede de transmissão de energia elétrica

Pós-graduação em Engenharia Elétrica - FEIS

Metodologia de simulação numérica do comportamento térmico em equipamentos eletroeletrônicos

Pós-graduação em Engenharia Elétrica - FEIS

Análise matemática da potência gerada por sistemas fotovoltáicos e suas aplicações

A radiação solar constitui-se numa inesgotável fonte energética, havendo um enorme potencial de utilização por meio de sistemas de captação e conversão em outra forma de energia. Para a conversão direta da energia solar em elétrica, são utilizadas células fotovoltaicas constituídas, que associadas constituem um módulo fotovoltaico, sendo que também quando agrupados, formam painéis fotovoltaicos. Estes painéis associados a outros equipamentos que transformam ou armazenam energia elétrica para que ela possa ser utilizada é chamado de sistema fotovoltaico. Neste trabalho, foram determinadas analiticamente formas de obtenção de curvas de corrente e potência fotovoltaicas, e também o ponto de potência máxima. Tais métodos foram aplicados no sistema fotovoltaico localizado na FCA/UNESP, sendo utilizado um sistema constituído por três módulos fotovoltaicos. Para o desenvolvimento das equações que regem a potência dos sistemas fotovoltaicos, procurou-se estudar o circuito elétrico de células fotovoltaicas, sendo necessária também a aplicação de métodos numéricos iterativos para a determinação de alguns parâmetros elétricos. De acordo com os teoremas apresentados, foi possível determinar as expressões analíticas da resistência série e do ponto de potência máxima de uma célula fotovoltaica, possibilitando a geração dos gráficos de tais funções com os dados obtidos experimentalmente. Comparando-se os valores obtidos pelas funções com os valores padrões do sistema fotovoltaico instalado, o valor calculado apresentou um erro de 1,03% em relação ao dado pelo fabricante, representando uma excelente aproximação. Desta forma, pode-se concluir que os métodos e teoremas dos sistemas fotovoltaicos apresentados podem servir de auxílio a futuros dimensionamentos para aplicações destes sistemas.

Comportamento do fator de potência de uma serra de fita vertical e de um picador em uma serraria

This work aims to present the electrical behavior of two mechanical processing equipment of wood, the saw vertical tape and the wood chipper. Their characteristics in real operating conditions and the electrical behavior of devices in terms of energy efficiency is shown through the study of individual power factor are presented in this study. It was observed that both devices operate unloaded for some intervals of time and this contributes to a low power factor. It is concluded that improved production planning and better preparation of the operators in the operations of sawing wood, in order to improve the power factor in sawmills is necessary.

Topologia de gerador de distúrbios elétricos baseada em conversores de potência

Electrical disturbances such as voltage sags, interruptions and voltage unbalances might cause serious problems for the end-user and for the companies of generation and transmission of energy. Few years ago, those companies have been using methods and equipments of protection to avoid the disturbances’ presence or to mitigate their effects on the power system. Disturbances generators are used to analyse the behavior of electrical and electronic equipments affected by disturbances. The analysis of those failures allows the development of appropriated protection equipments. In this paper, the development of a disturbances generator based on power converters is presented. The disturbance generator developed is able to generate some symmetrical disturbances, such as: voltage sags, voltage swells and harmonic distortion. The control strategy used in the disturbance generator is based on discrete and repetitive control. The steps of the design of the control and of the filter used for reducing harmonic in the output, are detailed in the text. Are presented the obtained results on computational simulations and the obtained results on laboratory tests.

Proposta de mecanismo de lavagem em equipamentos de beneficiamento de tomate de mesa

The cleanness level in fresh market tomatoes cleaning equipment is essential for consumer acceptance and conservation of product quality. However, the washing process in cleaning current equipments demands an excessive volume of water, leading to serious economic and environmental concerns. The objective of this work was to contribute with technical information for the washing system optimization. The conventional washing system currently used in cleaning equipment, which consists of perforated PVC pipes, was compared with a proposed system which uses commercial sprays. Characteristic curves (flow rate versus pressure) for both systems were determined in lab conditions and the respective water consumptions were compared. The results confirmed the excess of water consumption in the conventional washing systems, and the proposed system proved that is possible to reduce it, and the use of sprays allowed the rational use of the water.

Caracterização de dois equipamentos de beneficiamento e classificação de tomates para mesa

On the last years, in Brazil, sorting and classifying fruits and vegetables using packing lines have increased. This work aimed at characterizing the cleaning process for fresh market tomatoes at two packing lines, one imported and one national located at Campinas, São Paulo State. Characterization included data, number, types and brushes velocity, water use, fruit standing time and cleaning efficiency. Standing time was measured correlating to fruit diameter (CEAGESP). For measuring cleaning efficiency an equipment was developed that was mainly composed of a ring involved with white cloth. Samples were taken before and after the cleaning step and evaluated using a colorimeter HUNTER Lab. The results showed a strong difference between the two equipments. The imported equipment showed lower number on brushes and rotation than national one, however a higher water consumption. For imported equipments this relation was not found. Both packing lines showed the same cleaning efficiency. Cleaning efficiency is related to be an interaction among the studies parameters, and it could be necessary a better management than the one used on both equipments.

COMPARAÇÃO DAS PROPRIEDADES REOLÓGICAS DA MASSA DE CACAU TORRADA CONVENCIONALMENTE E POR MICROONDAS

Two kinds of roasting cocoa system: conventional batch method in electrical oven, and by microwaves, in a continuous microwave rotary applicator (2450MHz), were compared with respect to viscosity. Cocoa was roasted in whole beans and in nibs. The variable used in the microwave treatment was the power density applied to the whole beans (254,45 to 290,80 Wh/kg) and to the nibs (227,27 to 262,23 Wh/kg), with a constant holding time of 10 minutes. The variable used in the conventional roasting process was the roasting time of the beans (40 to 44 min) and the nibs (34 to 38 min), with constant temperature in the jacket of electric oven (150°C). Viscosity was measured in a Brookfield rheometer (mod RV-DVIII) at 40°C. In general, the plastic viscosity of the microwaved samples was lower than that of the conventional roasted samples. Also the nibs showed lower viscosities than the whole beans when roasted in the electric oven. The viscosity of the samples roasted in the microwave oven was lower in the whole beans than in the nibs. The product was sensorially evaluated by three experts in cocoa flavour, and it was shown that the flavour of the microwave roasted products was similar to that of the conventionally roasted products, with the advantage of a reduction in process time.

Utilização de recursos ópticos e equipamentos por escolares com deficiência visual

PURPOSE: To verify perceptions and conduct of students with visual impairment regarding devices and equipment utilized in schooling process. METHODS: A transversal descriptive study on a population of 12-year-old or older students in schooling process, affected by congenital or acquired visual impairment, inserted in the government teaching system of Campinas during the year 2000. An interview quiz, created based on an exploratory study was applied. RESULTS: A group of 26 students, 46% of them with low vision and 53.8% affected by blindness was obtained. Most of the students were from fundamental teaching courses (65.4%), studying in schools with classrooms provided with devices (73.1%). Among the resources used in reading and writing activities, 94.1% of the students reported they used the Braille system and 81.8% reported that the reading subject was dictated by a colleague. Most of the students with low vision wore glasses (91.7%), and 33.3% utilized a magnifying glass as optical devices. Among the non-optical devices, the most common were the environmental ones, getting closer to the blackboard (75.0%) and to the window (66.7%) for better lighting. CONCLUSIONS: It became evident that students with low vision eye-sight made use of devices meant for bearers of blindness, such as applying the Braille system. A reduced number of low vision students making use of optical and non-optical devices applicable to their problems were observed, indicating a probable unawareness of their visual potential and the appropriate devices to improve efficiency.

Comparação entre métodos para mensuração da potência aeróbia em atletas tetraplégicos= : Comparison of methods for aerobic power assessment in athletes with tetraplegia

Universidade Estadual de Campinas . Faculdade de Educação Física

Mensuração da potência mecânica em esforços de alta intensidade na condição laboratorial de corrida atada e na condição de campo em corrida semi-atada e livre

Universidade Estadual de Campinas . Faculdade de Educação Física