189 resultados para Taxa de queima


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The present work aims to study the characteristics of the alloy Al - 7 % Si - 0 , 3Mg ( AA356 ) , more specifically characterize the macrostructure and microstructure and mechanical properties of the alloy ingots AA356 obtained in metal molds and sand molds for power studying the structures through the difference of cooling rates . This alloy is explained by the fact of referring league has excellent combination of properties such as low solidification shrinkage and good fluidity, good weldability , high wear resistance , high strength to weight ratio, has wide application in general engineering , and particularly in the automotive and aerospace engineering . In this work we will verify this difference in properties through two different cooling rates . We monitor the solid solidification temperatures by thermocouples building with them the cooling curve as a tool that will aid us to evaluate the effectiveness of the grain refining because it achieved with some important properties of the alloy as the latent heat of solidification fraction the liquid and solid temperatures, the total solidification time, and identify the presence of inoculants for grain refinement. Thermal analysis will be supported by the study of graphic software “Origin “will be achieved where the cooling curve and its first derivative that is the cooling rate. Made thermal analysis, analysis will be made in macrographs ingots obtained for observation of macrostructures obtained in both types of ingots and also analysis of micrographs where sampling will occur in strategic positions ingots to correlate with the microstructure. Finally will be collecting data from Brinell hardness of ingots and so then correlating the properties of their respective ingots with cooling rate. We found that obtained with cast metal ingots showed superior properties to the ingots obtained with sand mold

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The objective of this study was to investigate the influence of previous active static stretch on the peak torque (PT) and rate of force development (TDF) during isokinetic concentric contractions at 60 and 180.s-1 in active individuals. Twelve active subjects with ages between 18 and 30 years participated of this study. The individuals were submitted in different days to the following tests: 1) Familiarization session to the isokinetic dynamometer; 2) Five maximal isokinetic concentric contractions for knee extensors at each angular velocity (60 and 180.s-1) to determine PT and TDF (Control), and; 3) Two active static stretching exercises for the dominant leg extensors (10 x 30 s for each exercise, with 20 s of rest). After the stretching, the isokinetic test was repeated (Post-Stretching). The conditions 2 and 3 were performed in random order. There was no significant modification after the stretch exercises on the PT, angle and time at which the PT was attained, at 60 and 180º.s-1. In the same way, there was no significant modification on the TDF and angle at which the maximal TDF was attained in both angular speeds. In other way, the time to attain maximal TDF (TTDF) at 180º.s-1 was significantly lower after the stretching (Pre - 98.3 ± 27.5 ms and Post - 86.6 ± 30.2 ms). There was significant modification on the torque (60 and 180º.s-1) and time (60º.s-1) at different delta of angle variations, obtained at 60º.s-1 at Control and Post-Stretching conditions. However, there was significant reduction of time after the stretching exercises on delta of angle variations of 90-88º (Pre - 46.6 ± 6.5 ms and Post - 44.1 ± 5.1 ms), 88-85º (Pre - 65.8 ± 7.9 ms and Post - 63.3 ± 4.9 ms) and 85-80º (Pre - 93.3 ± 7.7 ms and Post - 90.0 ± 4.2 ms) at 180º.s-1. With base on these data, it is possible to conclude that PT and TDF do not modify after static stretching, irrespectively on the speed...(Complete abstract click electronic access below)

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With the growing world energy demand mainly from developing countries like Brazil, Russia, India and China, the search for efficient sources of energy becomes a challenge for the coming years. Among the most widely used alternative sources, biomass is the one that grows in a more pronounced way. This study will assess the real possibility of having it as a heat source in an Organic Rankine Cycle, which employ heat transfer fluids as working fluids instead of water. From a regional data collection in agricultural production and their potential rice production and the resulting husk was defined as more appropriate. The availability of husks together with an amount of eucalyptus wood, provided by a company in the region on a monthly basis, were analyzed, and the low participation of the wood was discarded by the thermal contribution of little significance. Based on this, it was established the calorific value of fuel for thermodynamic calculations and the cycle to be used. It was then carried out the choice of working fluid from the literature and their availability in the library of software used for the simulations, the Engineering Equation Solver - ESS. The fluid most appropriate for the burning of biomass, Octamethyltrisiloxane (OMTS), was not included in the software and so the R227ea and R134a were selected. After the initial parameters modeling definition, as condensing temperature, efficiency and live steam conditions, the simulations were performed, and only the R227ea remained within the feasible thermodynamic and technological ranges. With this fluid the turbine power output was 265.7 [kW] for a scenario of 24 hours/day burning, 800.3 [kW] to biomass burning for 8 hours/day and 2134 [kW] for burning only 3 hours/day. The thermal efficiency of the cycle remained in the range of 6%, and for plants operating with the most... (Complete Abstract click eletronic access below)

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Studies regarding the quality and quantity of water have become more and more important because of the increasing negative environmental impacts occurred and their scarcity increase as well. At the Center of Tropical Fish Research (Centro de Pesquisas de Peixes Tropicais - CEPTAlIBAMA) located in the city of Pirassununga, SP, there is a dam named Represa Velha which supplies 128 tanks that are fish hatcheries. This dam takes in part of the Barrinha stream micro-basin where it has been observed strong impacts due to the deforestation of its support forest, as well an the intensive agricultural activities in the neighboring areas. There has been established and distributed 13 points of water-collectors disposed inside the stream and the dam. The water samples were taken from the stream only from its surface because of the low depth and, inside. In the dam, the water samples were taken at the water column, at a 50cm distance over the sediment. In every point of collection inside the dam, it was placed a chamber of sedimentation, vertically in the water column at a 70% height from the total depth. The collections took place during the dry/cold and raining/warm periods of the years 2000 and 2001. Then, it were analyzed the physical, physical-chemical, chemical and micro-biological parameters of the water samples. The obtained results were statistically analyzed throughout the SAS system (Statistical Analisys System). Parameters such as total phosphate, nitrate, nitrite and turbidity were within the established limits for the Class 2 water, according to the n° 20/1986 CONAMA Resolução. However, the total and Escherichia coli coliforms, mainly inside the Barrinha stream, had showed values above of the established limits for the same... (Complete abstract click electronic access below)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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This paper consists in the evaluation of the exposure rate to ionizing radiation to which professionals working in surgical procedures which require radiological examinations are subjected. Were initially performed real-time readings of exposure rate within four distinct operating rooms during the execution of four surgical procedures that made use of fluoroscopy equipment (including three orthopedic surgeries, one in the shoulder, one in the arm, another for deployment of metal pin in the leg region, and a fourth for vascular procedure); in these surgeries were used ionization chamber detector and an electrometer. In order to check the values achieved, was made a re-evaluation of the distribution of the rate of exposure to radiation, from the surgical procedures, now with thermoluminescent dosimeters (TLDs). For this, thirty TLDs were distributed in the operating rooms, arranged in points of interest as occupation by professionals. The TLDs were prepared for thirty consecutive days, after which they were removed and replaced with new dosimeters not exposed yet. The dosimeters were subjected to reading of the rate of exposure; this procedure was repeated for four months without interruption. The quantification of the results sought primarily to convert the rate of exposure for equivalent dose rate, both in measurements with ionization chamber as in measurements with TLDs, in order to highlight the presence of the biological effect of ionizing radiation for comparisons within scientific context. Then, the results were plotted to establish the relationship between the values of equivalent dose and the distance to the central axis of the x -ray source, confirming the inverse square law for distance. Finally, the values were associated with the maximum limit recommended by the legislation for occupationally exposed individuals. The methodology for the analysis and quantification of the data in this work aims at implementing a work plan that meets ...

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Pós-graduação em Engenharia Mecânica - FEIS

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Pós-graduação em Engenharia Mecânica - FEG

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The understanding of the subfamily Landrevinae has been modified by different authors since its creation. In the neotropics three genera are known to the present: Odontogryllus Saussure, 1877 (one from México, the others amazonian), Brasilodontus de Mello, 1992 with two species (from Brazilian Atlantic Forest), e Valchica de Mello, 1992 with one species (from Costa Rica). De Mello (1992) erroneously created the tribe Odontogryllini for this cluster of neotropical genera, here suppressed. In the present paper we revise and add new species to Brasilodontus and describe two monotypic genera, Xulavuna n. gen. and Yarrubura, n. gen. An identification key to the genera of neotropical Landrevinae is presented as well as one for the species of Brasilodontus. The male fore wings of Xulavuna adenoptera n. sp. is remarkable regarding its shape and its glandular condition

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The objective of this study was to test the validity of the real exchange rate in the long run. For that five tests were performed based on equation, which relates to real exchange rate, international trade, domestic income. The main difference is that the tests when we are working with quarterly data, the parameters are significantly different from zero – i.e., the variables real exchange rate, international trade, domestic income and net exports on long term relationship – and, moreover, the signs are as expected. This implies that it is possible to increase exports with currency devaluation. Thus, based on data and tests that work we conclude that the exchange rate is an important instrument of trade policy, given that devaluations are valid even in the long term.

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The objective of this study is to examine if economic growth in Brazil was blocking due to external constraints, that is, in consequence of its Balance of Payments. We work with the approach first proposed by Thirlwall (1979) which was later modified by Lima and Carvalho (2009). We can conclude that economic growth was restricted by the external sector, which is consistent with the economic history of Brazil, and verify that the real exchange rate, and to influence the trade balance in the course run, also excerce some influence on this account balance of payments in the long run.