913 resultados para Load impact load capacity
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Environmental aspects have been acknowledged as an important issue in decision making at any field during the last two decades. There are several available methodologies able to assess the environmental burden, among which the Ecological Footprint has been widely used due to its easy-to-understand final indicator. However, its theoretical base has been target of some criticisms about the inadequate representation of the sustainability concept by its final indicator. In a parallel way, efforts have been made to use the theoretical strength of the Emergy Accounting to obtain an index similar to that supplied by the Ecological Footprint. Focusing on these aspects, this work assesses the support area (SA) index for Brazilian sugarcane and American corn crop through four different approaches: Embodied Energy Analysis (SA(EE)), Ecological Footprint (SA(EF)), Renewable Empower Density (SA(R)), and Emergy Net Primary Productivity (SA(NPP)). Results indicate that the load on environment varies accordingly to the methodology considered for its calculation, in which emergy approach showed the higher values. Focusing on crops comparison, the load by producing both crops are similar with an average of 0.04 ha obtained by SA(EE), 1.86 ha by SA(EF), 4.24 ha by SA(R), and 4.32 ha by SA(NPP). Discussion indicates that support area calculated using Emergy Accounting is more eligible to represent the load on the environment due to its global scale view. Nevertheless, each methodology has its contribution depending of the study objectives, but it is important to consider the real meaning and the scope of each one. (C) 2012 Elsevier Ltd. All rights reserved.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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This work aims at presenting a no-break system for microcomputers using ultracapacitors in replacement of the conventional chemical batteries. We analyzed the most relevant data about average power consumption of microcomputers, electrical and mechanical characteristics of ultracapacitors and operation of no-break power circuits, to propose a configuration capable of working properly with a microcomputer switching mode power supply. Our solution was a sixteen-component ultracapacitor bank, with a total capacitance of 350 F and voltage of 10.8 V, adequate to integrate a low-capacity no-break system, capable of feeding a load of 180 Wh, during 75 s. Our proposed no-break increases the reliability of microcomputers by reducing the probability of user data losses, in case of a power grid failure, offering, so, a high benefit-cost ratio. The replacement of the battery by ultracapacitors allows a quick no-break recharge and low maintenance costs, since these modern components have a lifetime longer than the batteries. Moreover, this solution reduces the environmental impact and eliminates the constant recharge of the energy storage device.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Polymeric insulation is an increasing tendency in projects and maintenance of electrical networks for power distribution and transmission. Electrical power devices (e. g., insulators and surge arresters) developed by using polymeric insulation presents many advantages compared to the prior power components using ceramic insulation, such as: a better performance under high pollution environment; high hydrophobicity; high resistance to mechanical, electrical and chemical stresses. The practice with silicone insulators in polluted environments has shown that the ideal performance is directly related to insulator design and polymer formulation. One of the most common misunderstandings in the design of silicone compounds for insulators is the amount of inorganic load used in their formulation. This paper attempts to clarify how the variation of the inorganic load amount affects physicochemical characteristics of different silicone compounds. The physicochemical evaluation is performed from several measurements, such as: density, hardness, elongation, tensile strength. In addition, the evaluation of the physicochemical structure is carried out using infrared test and scanning electronic microscopy (SEM). The electrical analysis is performed from the electric tracking wheel and erosion test, in agreement with the recommendation of the International Electrotechnical Commission (IEC). (C) 2014 Elsevier Ltd. All rights reserved.
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Among all predictive maintenance techniques the oil analysis and vibration analysis are the most important for monitoring some mechanical systems. The integration of these techniques has potential to improve industrial maintenance practices and provide a better economic gain for industries. To study the integration of these two techniques, a test rig was set up to obtain an extreme working condition for the worm reducer used in this paper. The test rig was composed by a motor connected to a reducer through a flexible coupling and with an unbalanced load. The analysis of the results carried out by using a sample of the oil recommended by the manufacturer in extreme conditions, and using liquid contaminant is presented. From the results it was observed that if there is an abnormal instantaneous load in a system, the subsequent vibration analysis may not perceive what occurred if there was no permanent damage, which is not the case with the lubricant analysis.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Purpose: To evaluate the survival rate, success rate, load to fracture, and finite element analysis (FEA) of maxillary central incisors and canines restored using ceramic veneers and varying preparation designs.Methods and Materials: Thirty human maxillary central incisors and 30 canines were allocated to the following four groups (n=15) based on the preparation design and type of tooth: Gr1 = central incisor with a conservative preparation; Gr2 = central incisor with a conventional preparation with palatal chamfer; Gr3 = canine with a conservative preparation; Gr4 = canine with a conventional preparation with palatal chamfer. Ceramic veneers (lithium disilicate) were fabricated and adhesively cemented (Variolink Veneer). The specimens were subjected to 4 x 106 mechanical cycles and evaluated at every 500,000 cycles to detect failures. Specimens that survived were subjected to a load to fracture test. Bidimensional models were modeled (Rhinoceros 4.0) and evaluated (MSC.Patrans 2005r2 and MSC.Marc 2005r2) on the basis of their maximum principal stress (MPS) values. Survival rate values were analyzed using the Kaplan-Meier test (alpha = 0.05) and load to fracture values were analyzed using the Student t-test (alpha = 0.05).Results: All groups showed 100% survival rates. The Student t-test did not show any difference between the groups for load to fracture. FEA showed higher MPS values in the specimens restored using veneers with conventional preparation design with palatal chamfer.Conclusion: Preparation design did not affect the fracture load of canines and central incisors, but the veneers with conventional preparation design with palatal chamfer exhibited a tendency to generate higher MPS values.
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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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The objective of this work is to analyze the viability of incorporation in a microcomputer box of a nobreak with an ultracapacitor as energy storage device, substituting the conventional chemical battery. An advantage of this inclusion is cost reduction because a specific metallic or plastic frame won’t be necessary to protect the components of the nobreak; the microcomputer metallic frame offers the necessary protection for both equipments. Moreover, a large quantity of internal space of microcomputers box isn’t used, and is possible to use it to wrap up the nobreak. This work uses data about average power consumption of microcomputers; operation of switching mode power supplies for microcomputers; electrical and mechanical characteristics of ultracapacitors and operation of power circuits of nobreaks, with the purpose of present a study of energy storage capacity that an ultracapacitor should have to allow a safe switching off of a microcomputer in case of electrical network fail. It was noticed that the use of ultracapacitors is feasible to feed an 180 W load for 75 s, using a capacitive bank with sixteen ultracapacitors, with a total capacitance of 350 F and voltage of 10,8 V. The use of the proposed nobreak increases the reliability of the microcomputer by reducing the probability of user data losses in case of an electrical network fail, offering a high cost/benefit product. The substitution of the battery by an ultracapacitor allows a quick nobreak recharge, with low maintenance costs, since ultracapacitors have a lifetime bigger than batteries; beyond reducing the environmental impact, because they don’t use potentially toxic chemical compounds
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The aim of this study was evaluate the dental enamel after whitening treatment with Opalescence Boost PF® 38%, correlating the structural alterations in the surface of the enamel with its respective pH and verify if whitened teeth submitted to different finishing and polishing techniques show similar surface texture to healthy teeth (control group). Sixty premolars were divided in 6 groups (n = 10), which had been immersed in artificial saliva during all the experiment. Protocol whitening was performed according to the manufacturer recommendations, and then the specimens were submitted to different polishing technique with Sof-Lex Pop On® disks, Flex Diamond® felt disks using two different micrometric polishing pastes (Enamelize® and Diamond Polish®) and two nanometric polishing pastes (Lummina-E Diamond and Lummina-E Alumina), according to the groups. Representative specimens were analyzed in scanning electronic microscopy (SEM). Whitening gel used in this experiment had modified the morphologic aspect of the enamel surface. It was found that two nanometric polishing pastes (G5 and G6) promoted a less rough surface compared to control group even after the whitening process.
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In view of the low loading values commonly employed in dentistry, a load-application device (LAD) was developed as option to the universal testing machine (UTM), using strain gauge analysis. The aim of this study was to develop a load-application device (LAD) and compare the LAD with the UTM apparatus under axial and non-axial loads. An external hexagonal implant was inserted into a polyurethane block and one EsthetiCone abutment was connected to the implant. A plastic prosthetic cylinder was screwed onto the abutment and a conical pattern crown was fabricated using acrylic resin. An impression was made and ten identical standard acrylic resin patterns were obtained from the crown impression, which were cast in nickel-chromium alloy (n=10). Four strain gauges were bonded diametrically around the implant. The specimens were subjected to central (C) and lateral (L) axial loads of 30 kgf, on both devices: G1: LAD/C; G2: LAD/L; G3: UTM/C; G4: UTM/L. The data (με) were statistically analyzed by repeated measures ANOVA and Tukey's test (p<0.05). No statistically significant difference was found between the UTM and LAD devices, regardless of the type of load. It was concluded that the LAD is a reliable alternative, which induces microstrains to implants similar to those obtained with the UTM.
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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)