107 resultados para compressed air energy storage
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Pós-graduação em Agronomia (Energia na Agricultura) - FCA
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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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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Pós-graduação em Agronomia (Energia na Agricultura) - FCA
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A significant increase of surface hydrophilicity of copper and gold surfaces was obtained after atmospheric pressure plasma treatment using the surface dielectric barrier discharge with specific electrode geometry, the so-called diffuse coplanar surface barrier discharge. Surface wettability was estimated using the sessile drop method with further calculation of the surface free energy. After the plasma treatments, it was observed that the treated surfaces exhibited hydrophobic recovery (or aging effect). The aging effect was studied in different storage environments, such as air, low and high vacuum. The role of plasma and the reasons of the following aging effect are discussed with respect to the observed hydrophilic recovery after immersing the aged surfaces into deionized water. The changes in the surface morphology, composition and bond structure are presented and discussed as well. (C) 2013 Elsevier B. V. All rights reserved.
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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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Statement of problem. Removable partial dentures are affected by fatigue because of the cyclic mechanism of the masticatory system ansi frequent insertion and removal. Titanium and its alloys have been used in the manufacture of denture frameworks; however, preventive agents with fluorides are thought to attack titanium alloy surfaces.Purpose. This study evaluated, compared, analyzed the corrosion-fatigue life of commercially pure titanium and Ti-6Al-4V alloy in different storage environments.Material and methods. For each metal, 33 dumbbell rods, 2.3 mm in diameter at the central segment, were cast in the Rematitan system. Corrosion-fatigue strength test was carried out through a universal testing machine with a load 30% lon er than the 0.2% offset yield strength and a combined influence of different: environments: in air at room temperature, with synthetic saliva, and with fluoride synthetic saliva. After failure, the number of cycles were recorded, and fracture surfaces were examined with on SEM.Results. ANOVA and Tukey's multiple comparison rest indicated that Ti-6Al-4V alloy achieved 21,269 cycles (SD = 8,355) against 19,157 cycles (SD = 3,624) for the commercially purr Ti. There were no significant differences between either metal in the corrosion-fatigue life for dry specimens, but when the solutions were present, the fatigue life was significantly reduced, probably because of the product-ion of corrosion pits caused by superficial reactions.
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The use of refrigeration and air conditioning systems is of fundamental importance when it comes to air-conditioning of environments. Also important is the use of electricity for equipments’ operation related to these systems. Due to high cost of charging for this type of energy, factors economy and efficiency occupy key roles among design parameters of a system. One of the ways to get this economy is the use of a technique called thermal storage, or cold storage, which intends to move the required loads during peak time and also their equalizing, so that the energy is transferred from the peak time to non-peak time, thereby reducing the cost of energy consumed. Cold can be stored in the form of ice or ice water. This work aims to perform a technical-economic analysis of a mall located in Vale do Paraíba checking the feasibility of deploying a thermal storage system to achieve an economy in the cost of the energy used by the establishment. Through the parameters measured by the concessionaire of energy we can get the values of energy demand and power consumed, which will serve as basis for calculation for the study. The results obtained allow the development of two alternative proposals to the current configuration, one chosen by the criteria and results presented by technical-economic and energy analysis
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This study evaluated the efficiency of a toothbrush holder to prevent contamination of toothbrushes used by preschool children. For that, the sample was composed by children 6 years old, enrolled in an educational and recreational center in Araraquara/SP, and divided into 3 groups: G1: same continuing routine storage toothbrushes, G2: children received only a new toothbrush holder for storage; G3: they received new toothbrushes holder for storage and solution of chlorhexidine digluconate to 0.12% to dabble in the toothbrush after use. After brushing their teeth, toothbrushes were collected for microbiological analysis. The data were analyzed using the distribution of frequencies. It was observed that, in general, higher prevalence of the microorganism in the toothbrushes was Streptococcus viridans (58.97%), followed by Estafilococcus (35.90%), the bacillus of air (28.21%) and Neisseria mucosa (5.13%). Evaluating frequency, it was noted that the contamination presented by Streptococcus is higher in G1 when compared to G2 and G3, while for Estafilococcus, the presence was more significant in G3. Thus, it was concluded that the use of new toothbrushes holder able to avoid direct contact between brushes and allow drying without smothering could be an excellent alternative to educational institutions that require the storage group.
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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)
Analysis of oxy-fuel combustion as an alternative to combustion with air in metal reheating furnaces
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Using oxygen instead of air in a burning process is at present being widely discussed as an option to reduce CO2 emissions. One of the possibilities is to maintain the combustion reaction at the same energy release level as burning with air, which reduces fuel consumption and the emission rates of CO2. A thermal simulation was made for metal reheating furnaces, which operate at a temperature in the range of 1150-1250 degrees C, using natural gas with a 5% excess of oxygen, maintaining fixed values for pressure and combustion temperature. The theoretical results show that it is possible to reduce the consumption of fuel, and this reduction depends on the amount of heat that can be recovered during the air pre-heating process. The analysis was further conducted by considering the 2012 costs of natural gas and oxygen in Brazil. The use of oxygen showed to be economically viable for large furnaces that operate with conventional heat recovering systems (those that provide pre-heated air at temperatures near 400 degrees C). (C) 2014 Elsevier Ltd. All rights reserved.
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An interdisciplinary study was conducted to evaluate the effects of drying and storage time on changes in the quality of natural and fully washed coffees beans dried out in the yard and mechanically dried at a temperature of 60/40°C in air dryer machine. The coffee beans (Coffea arabica L.) harvested in cherries were processed by dry and wet methods, being subjected to pre-drying yard, followed by drying yard in the sun with air heated of 60/40°C until it reached the water content of 11% (wb). After reached the thermal equilibrium with the environment, the beans were packed in jute bag with a capacity of five kilograms and stored in uncontrolled environment during the period of one year, and removing material from each treatment every three months. To characterize the effect of drying and storage time on the coffee quality different methodologies was evaluated. It was observed less drying time for the fully washed coffee 60/40°C, and thus less energy consumed in the drying process until the point of storage, for the natural coffee there was significant effect of time on the chemical quality, biochemical and sensory; fully washed coffee proved to be more tolerant to drying than natural coffee, regardless of drying method, showing a better drink quality and less variation in chemical composition and biochemistry.