582 resultados para condutividade
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Pós-graduação em Química - IQ
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Pós-graduação em Engenharia Mecânica - FEG
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Pós-graduação em Química - IQ
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Dissipadores de calor recobertos com filmes de diamante CVD foram desenvolvidos para acoplar a semicondutores, utilizando-se do Laboratório de Deposição de Filmes de Diamante CVD, na UNESP - Campus de Guaratinguetá e o Laboratório de Diamantes da Universidade São Francisco, em Itatiba, SP. Analisou-se o filme de diamante CVD sobre o silício, para emprego como dissipador de calor, porque o filme de diamante CVD pode ter o valor da condutividade térmica até cinco vezes superior ao do cobre e de dez vezes a do alumínio. Os filmes foram obtidos via deposição através de reator de filamento quente, trabalhando-se com vários filamentos retilíneos em paralelo, resultando assim em um processo que visou obter um filme mais uniforme e com grande área de deposição. Os dados para análises da composição química superficial dos filmes foram obtidos por Difração de Raios-X, Dispersão de Energia de Raios-X e para a verificação da morfologia e espessura do filme foi utilizada a Microscopia Eletrônica de Varredura. Para a verificação do comportamento da temperatura sobre o dissipador com o filme de diamante CVD foi utilizada uma câmera de imagem termográfica, marca Fluke, modelo Ti 40 FT. Foram obtidos filmes de 2 e 10 ?m sobre o silício. Estas espessuras ainda não oferecem um desempenho mecânico que o torne autosustentado. Do ponto de vista de desempenho térmico as análises mostraram que, mesmo com pequena espessura, o filme de diamante CVD apresentou bom resultado experimental. Os principais desafios de construção para esse dissipador de calor são a obtenção do filme com espessura acima de um mm e a garantia da qualidade do filme com a repetitividade do processo em cujo caso torna-se necessário definir as dimensões do dissipador antes da deposição do filme.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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The contamination of underground waters is a subject of great importance, since a lot of people use this kind of source for public supply. This paperwork manages with how gas stations can contaminate these waters and what are some remediation techniques, used nowadays to solve this problem. The contamination caused by the gas stations can have its origin in the underground storage tanks when they suffer corrosion and show leaking problems. It’s a topic of great relevance, because the hydrocarbons derivated from petroleum present in the fuels can stay for a long time in the environment. Besides that, an analyses of the risk of contamination by gas stations in the city of Rio Claro was made based on three parameters: density of the gas stations, depth of the underground water and hydraulic conductivity. To achieve such goal, maps were elaborated considering those parameters individually and considering the three of them together. Analyzing those maps, it was concluded see that the spots that represent the biggest risks of contamination in Rio Claro are located southeast and center-west.
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We conducted a study of the quality of water distributed by Artesian Well in relation to water supply served by the public for purposes of human consumption of UNESP Campus Guaratinguetá. Two sections of the network were randomly chosen and monitored for 105 days: the stretch of the pipeline started off the Water Treatment Station of the Autonomous Service of Water, Sewage and waste in the Municipality of Guaratinguetá and ended in a point consumption of the Child Family Center, while the section B began at the output of an artesian well and finished in a point of consumption of the Department of Civil Engineering. It is the deterioration of water quality in parts A and B, through comparative analysis of Bicarbonates, Total Hardness, Total Iron, free residual chlorine, pH, Total Residual, Turbidity, Conductivity, Color, Fecal Coliforms and Total Coliforms. Among the observations that can be highlighted: the Total Hardness was found in highest concentration in the extract; for Total Iron significant variations were obtained for both parts, and reduction of this parameter in two points of consumption analyzed, not the expected increase concentration, because the contact of water along the pipe, the CRL showed significant depletion to section A, which can be related to impurities in the water, the presence of biofilm on the walls of pipes, or because this is the stretch of greater extent to be covered by water for pH, this indicated that the water is alkaline and slightly acidic stretch in section B; Turbidity was found for the higher concentration to the passage, and a considerable reduction of this parameter at point consumption due to deposition of particulate matter along the stretch, the conductivity also showed a higher concentration in the extract, as well as an increase in this parameter at the point of consumption. Upon leaving ... (Complete abstract click electronic access below)
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During the twentieth century the inorganic electronics was largely developed being present in various industrial equipment or household use. However, at the end of that century were verified electronic properties in organic compounds, giving rise to the field of organic electronics. Since then, the physical properties of elementary devices such as diodes and organic transistors have been studied. In this work was studied the properties of diode devices fabricated with a semiconductor polymer, the poly-o-methoxyaniline (POMA). Devices containing electrodes of Au and Al were fabricated with semiconductor polymer of different doping levels. We found that the rectifying behavior for the heterojunctions metal/polimer are reached only for high doping level (with conductivity greater than 1,77. 10-9 S / cm), which gives the devices characteristic of a Schottky diode. The rectifying behavior was observed for electric fields of low magnitude, below the operating field (~ 600 V/cm), while for electric field greater than 600 V/cm the a linear behavior I vs.V was obtained. We determined that this Ohmic behavior arises from the charge transport over the volume of the semiconductor material after the lowering of the metal/semiconductor barrier. In devices with weakly doped semiconductor, the electrical resistance of the volume becomes high and the process of charge transportation is dominated by the volume, for any intensity of the applied electric field
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The glassy carbon is a material with a huge technological evolution. Due to its lightness, biocompatibility and their thermal and electrical properties this material finds applications in several industrial fields such as electronics, medical, aerospace and chemical. In order to explore the conductive properties of glassy carbon for use as modified electrodes, the present work aims the processing of monolithic and reticulated glassy carbon with colloidal copper for use in electrochemical applications. First, the best parameters for the cure of furfuryl alcohol resin doped were established through viscosimetry measurements and pressurized differential scanning calorimetry. The analysis of the micrographs of the cured resins show that copper concentrations above 3% weight, generate higher porosity in the material. The characterizations of the monolithic and reticulated glassy carbon resulting from carbonization were performed by scanning electron microscopy (SEM), Raman and Electrochemical impedance spectroscopy, and although it was not possible to detect the presence of copper by SEM, the influence of these particles have been observed by Raman and FT-IR spectra and electrochemical behavior of the material. The decrease in conductivity of monolithic and reticulated glassy carbon in the presence of copper may be related to the defects caused by the presence of copper in the structure of the material.
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A large proportion of fresh water is greatly impaired due to increasing pollution; this could be minimized through the expansion of investment in sanitation programs. But the major problem faced by third world countries and developing ones in this respect, is the high cost of projects and their implementation. In an attempt to find a simple technology, efficient and inexpensive, this study aimed to verify the effectiveness of using constructed wetland systems (CWS) for removal of bacteria and nutrients from sanitary sewer effluent from the STS Piracicamirim - Piracicaba - SP. The installation of prototypes was followed, and testing prior to regularize the flow held, but due to malfunction of these and outages of the STS activity can not evaluate the effectiveness of both as to the parameters proposed: temperature, pH, dissolved oxygen, conductivity, total dissolved solids (TDS), nitrite, nitrate, ammonia, total nitrogen, total phosphorus, chemical oxygen demand (COD), sulfide, sulfate, biochemical oxygen demand (BOD), total coliform and Escherichia coli. To establish results about the effectiveness of these types if the system were conducted literature reviews of papers published with the same theme. Analysis of these results showed fairly good efficiencies in wastewater treatment, especially for nutrients and coliforms
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No reservatório de Salto Grande (22º53’53’’S / 49º59’33’’W), Rio Paranapanema (SP/PR), é realizado um tipo de manejo (redução do nível de água) para redução da biomassa da macrófita submersa Egeria densa desde 2004. Estas plantas causam perdas econômicas para o programa de geração elétrica e infortúnio para a população local. O reservatório de Salto Grande possui lagoas marginais que apresentam elevada densidade dessas macrófitas e são tidas como ambientes de alta importância para o desenvolvimento, alimentação e reprodução de muitas assembléias, principalmente as de microcrustáceos zooplanctônicos. O objetivo deste trabalho foi analisar as mudanças na estrutura (composição, riqueza, abundância e diversidade) das assembléias de microcrustáceos zooplanctônicos (Cladocera e Copepoda) e suas relações com as alterações nas condições limnológicas decorrentes da variação de nível em duas lagoas marginais (Pedra Branca e Guaritá) em função do deplecionamento. Foram realizadas amostragens mensais de abril/2005 a julho/2006, além de coletas nictemerais durante o processo de deplecionamento (agosto/05) e um mês após o mesmo. Para a análise do zooplâncton foram amostrados 150 litros de água superficial em cada lagoa (região limnética). Simultaneamente, foram medidas as variáveis físicas e químicas da água: temperatura, pH, oxigênio dissolvido, condutividade elétrica, transparência, turbidez, material em suspensão (total, frações orgânica e inorgânica) e concentração de clorofila a. As variáveis limnológicas demonstraram um padrão de variação sazonal, além da influência do deplecionamento, principalmente sobre a temperatura e oxigênio dissolvido. O valor de riqueza encontrado para Cladocera foi elevado, totalizando 49 táxons. Os Copepoda foram analisados apenas até o nível de Ordem... (Resumo completo, clicar acesso eletrônico abaixo)