Desempenho de um painel fotovoltaico de baixa tensão, acoplado ao protótipo de um conversor dc/dc topologia Booster

Low voltage solar panels increase the reliability of solar panels due to reduction of in series associations the configurations of photovoltaic cells. The low voltage generation requires DCDC converters devices with high efficiency, enabling raise and regulate the output voltage. This study analyzes the performance of a photovoltaic panel of Solarex, MSX model 77, configured to generate an open circuit voltage of 10.5 V, with load voltage of 8.5 V, with short circuit current of 9 A and a power of 77 W. The solar panel was assembled in the isolated photovoltaic system configuration, with and without energy storage as an interface with a DCDC converter, Booster topology. The converter was designed and fabricated using SMD (Surface Mounted Devices) technology IC (integrated circuit) that regulates its output voltage at 14.2 V, with an efficiency of 87% and providing the load a maximum power of 20.88 W. The system was installed and instrumented for measurement and acquisition of the following data: luminosities, average global radiation (data of INPE Instituto Nacional de Pesquisas Espaciais), solar panel and environment temperatures, solar panel and DC-DC converter output voltages, panel, inverter, and battery charge output currents. The photovoltaic system was initially tested in the laboratory (simulating its functioning in ideal conditions of operation) and then subjected to testing in real field conditions. The panel inclination angle was set at 5.5°, consistent with the latitude of Natal city. Factors such as climatic conditions (simultaneous variations of temperature, solar luminosities and ra diation on the panel), values of load resistance, lower limit of the maximum power required by the load (20.88 W) were predominant factors that panel does not operate with energy efficiency levels greater than 5 to 6%. The average converter efficiency designed in the field test reached 95%

Estudo de um sistema híbrido de destilação solar para polimento de águas produzidas

The oil industry, experiencing a great economic and environmental impact, has increasingly invested in researches aiming a more satisfactory treatment of its largest effluent, i.e., produced water. These are mostly discarded at sea, without reuse and after a basic treatment. Such effluent contains a range of organic compounds with high toxicity and are difficult to remove, such as polycyclic aromatic hydrocarbons, salts, heavy metals, etc.. The main objective of this work was to study the solar distillation of produced water pre-treated to remove salts and other contaminants trough of a hybrid system with a pre-heater. This developed apparatus was called solar system, which consists of a solar heater and a conventional distillation solar still. The first device consisted of a water tank, a solar flat plate collector and a thermal reservoir. The solar distillator is of simple effect, with 1m2 of flat area and 20° of inclination. This dissertation was divided in five steps: measurements in the solar system, i.e. temperatures and distillate flow rate and weather data; modeling and simulation of the system; study of vapor-liquid equilibrium of the synthetic wastewater by the aqueous solution of p-xylene; physical and chemical analyses of samples of the feed, distillate and residue, as well as climatology pertinent variables of Natal-RN. The solar system was tested separately, with the supply water, aqueous NaCl and synthetic oil produced water. Temperature measurements were taken every minute of the thermal reservoir, water tank and distillator (liquid and vapor phases). Data of solar radiation and rainfall were obtained from INPE (National Institute for Space Research). The solar pre-heater demonstrated to be effective for the liquid systems tested. The reservoir fluid had an average temperature of 58°C, which enabled the feed to be pre-heated in the distillator. The temperature profile in the solar distillator showed a similar behavior to daily solar radiation, with temperatures near 70°C. The distillation had an average yield of 2.4 L /day, i.e., an efficiency of 27.2%. Mathematical modeling aided the identification of the most important variables and parameters in the solar system. The study of the vapor-liquid equilibrium from Total Organic Carbon (TOC) analysis indicated heteroazeotropia and the vapor phase resulted more concentrated in p-xylene. The physical-chemical analysis of pH, conductivity, Total Dissolved Solids (TDS), chlorides, cations (including heavy metals) and anions, the effluent distillate showed satisfactory results, which presents a potential for reuse. The climatological study indicates the region of Natal-RN as favorable to the operation of solar systems, but the use of auxiliary heating during periods of higher rainfall and cloud cover is also recommended

Micropartículas poliméricas à base de xilana e Eudragit® S-100 contendo mesalazina visando à liberação cólon-específica

Colon-specific drug delivery systems have attracted increasing attention from the pharmaceutical industry due to their ability of treating intestinal bowel diseases (IBD), which represent a public health problem in several countries. In spite of being considered a quite effective molecule for the treatment of IBD, mesalazine (5-ASA) is rapidly absorbed in the upper gastrointestinal tract and its systemic absorption leads to risks of adverse effects. The aim of this work was to develop a microparticulate system based on xylan and Eudragit® S- 100 (ES100) for colon-specific delivery of 5-ASA and evaluate the interaction between the polymers present in the systems. Additionaly, the physicochemical and rheological properties of xylan were also evaluated. Initially, xylan was extracted from corn cobs and characterized regarding the yield and rheological properties. Afterwards, 10 formulations were prepared in different xylan and ES100 weight ratios by spray-drying the polymer solutions in 0.6N NaOH and phosphate buffer pH 7.4. In addition, 3 formulations consisting of xylan microcapsules were produced by interfacial cross-linking polymerization and coated by ES100 by means of spray-drying in different polymer weight ratios of xylan and ES100. The microparticles were characterized regarding yield, morphology, homogeneity, visual aspect, crystallinity and thermal behavior. The polymer interaction was investigated by infrared spectroscopy. The extracted xylan was presented as a very fine and yellowish powder, with mean particle size smaller than 40μm. Regarding the rheological properties of xylan, they demonstrated that this polymer has a poor flow, low density and high cohesiveness. The microparticles obtained were shown to be spherical and aggregates could not be observed. They were found to present amorphous structure and have a very high thermal stability. The yield varied according to the polymer ratios. Moreover, it was confirmed that the interaction between xylan and ES100 occurs only by means of physical aggregation

A escola de ensino médio público noturno: uma conjuntura favorável ao protagonismo estudantil coletivo em contraposição ao protagonismo juvenil via empoderamento

Ce travail etude le protagonisme juvénile en école de enseignement sécondaire publique, avec emphase a l enseignement nocturne. Considere las médiations que determinent le paradigme du protagonisme juvénile defendu pour théoriciens pos modernes et documents de reforme de enseignement sécondaire brésilien. Montre que les explications sur le protagonisme juvénile font part d une conception de pouvoir juvenile, proposé pour organismes multilatérales avec la volonté de mobiliser les jeunes pauvres pour faire actions du combat a pauvreté dans les nations sur le point de développement, conjoncture auquel sont proposées théories et pratiques que viabilizent la subsistance des jeunes pauvres en situation de risque. Discute la question de pouvoir juvenile et indique que la proposition de le protagonisme juvénile via pouvoir ont une espace favorable dans le sphère du enseignement sécondaire, niveau de la plupart de jeunes. Montre que la défense de pouvoir juvenile occulte chances de actions étudiants collectifs que permetent une intervention sociopolitique au élève de enseignement sécondaire, qui ont selement une function de homologation. Propose une recherche de possibilités de incentifs a le protagonisme juvénile collectif ou protagonisme étudiant collectif, auquel le étudiant presente suggestions pour le planification et éxecution de activités didactique pédagogiques dans l`école publique de enseignement sécondaire. Defend que la gestion démocratique, avec emphase en procès participatif, c est la principal déterminacion pour le protagonisme étudiant collectif. Méthodiquement , considere las dimensions suivantes pour le protagonisme juvénile: a) configuration de protagonisme juvénile b) protagonisme juvénile dans perspective légal/institutionel ; c) enseignement sécondaire et protagonisme juvénile ; d) possibilité de construction de protagonisme étudiant collectif dans enseignement sécondaire nocturne en Rio Grande do Norte, état choisi pour recherche. Sistematize une technique de revision de litérature sur le thème et informations d une consultation de documents, au-delà de donné constants de Banc de donées de la recherche Le Enseignement Sécondaire Publique Nocturne :registre et analyse de expérience dans l état de Rio Grande do Norte. Conclusion : il faut contribuer pour débats sur la participation politique de les jeunes dans le enseignement sécondaire nocturne, en presentant possibilités reéles de protagonisme étudiant collectif ; opinions presentées pour élèves sont très importantes a une direction d un rôle académique fait pour institutions scolaires dans ce moment , parce que des étudiants sont correspondants a interlocuteurs privilégiés ; le élève peut et deut être consulté depuis le moment de élaboration jusqu a réalisation de activités scolaires ; bien que il y a des entraves et difficultés immanents au enseignement sécondaire publique nocturne, se forment noveaux espaces de démocratisation de idées