17 resultados para The electric industry
em Repositório Institucional UNESP - Universidade Estadual Paulista "Julio de Mesquita Filho"
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The main objective this article is describe a methodology for the calculation of the profile of the electric field in the level soil and proximities originated by electric energy transmission systems real and in operation in the country. It also is commented the equation used and your computational implementation in order to agile and to optimize the studies. The results of simulations were just presented for the transmission system in the voltage class 500 kV for simplify the understanding and space restriction in the article, very although five others types of configurations have also been used in the complete study with very voltages and respective classes. The results were animating and very nearby of values well-known of electric field of other and publications traditional in the area. The graphic exits of program for better visual comprehension and understanding went in accomplished in the plan and in the space © 2010 IEEE.
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This paper discusses the results of biodegradability tests of natural fibers used by the automotive industry, namely: coir, coir with latex, and sisal. The biodegradation of coir, coir with latex, and of sisal fibers was determined by monitoring the production of carbon dioxide (CO(2)) (IBAMA-E.1.1.2, 1988) and fungal growth (DIN 53739, 1984). The contents of total extractives, lignin, holocellulose, ashes, carbon, nitrogen and hydrogen of the fibers under study were determined in order to ascertain their actual content and to understand the results of the biodegradation tests. The production of CO(2) indicated low biodegradation, i.e., about 10% in mass, for all the materials after 45 days of testing; in other words, no material inhibited glucose degradation. However, the percentage of sisal fiber degradation was fourfold higher than that of coir with latex in the same period of aging. The fungal growth test showed a higher growth rate on sisal fibers, followed by coir without latex. In the case of coir with latex, we believe the fungal growth was not intense, because natural latex produces a bactericide or fungicide for its preservation during bleeding [1]. An evaluation of the materials after 90 days of aging tests revealed breaking of the fibers, particularly sisal and coir without latex, indicating fungal attack and biodegradation processes.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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This paper will present a failure analysis of a chain component, manufactured with AISI 1045 steel and used for sugarcane transport. During the fabrication process, this component is submitted to induction hardening, just on one surface, before the galvanizing process. The occurrence of surface cracks, during storage, disables the usage of these components. Chemical and metallographic analyses, tensile, fracture toughness, and hardness tests, and fractography were conducted in order to determine the causes of failure. The steel chemical composition was in accordance with AISI 1045. The metallographic analyses and fractography did not exhibit the presence of zinc into the cracks; this is an indication that the cracks occurred after the galvanizing process. Tensile and fracture toughness test results are as expected. The crack surface and the fracture toughness specimen surfaces showed two different fracture micromechanisms: dimples and intergranular. The delayed fracture associated with the predominance of intergranular fracture micromechanism at the induction hardened layer and the high hardness level is a clear indication of the hydrogen embrittlement. (c) 2008 Elsevier Ltd. All rights reserved.
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The Brazilian sugarcane industry shows a great amount of generated sludge which should be utilized adequately. Two sludge samples, aerobic and anaerobic, were collected. Both were evaluated by thermogravimetry and differential thermal analysis (DTA) as well as X-ray power diffraction. These compounds show variations of mass between 30 and 140 A degrees C due to the dehydration stage. The DTA curves show that the compounds have an exothermic reaction between 450 and 550 A degrees C, which indicates that this can be used as an energy source. Details concerning the kinetic parameters of the dehydration and thermal decomposition have also been described here. The kinetic study of these stages was evaluated in open crucibles under nitrogen atmosphere. The obtained data were evaluated with the isoconversional kinetic method. The results show that different activation energies were obtained for thermal decomposition.
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The evolution of the food sector has increased interest in the identification of new starches with distinct properties. Curcuma longa and Curcuma zedoaria rhizomes, which are already used in industry to obtain food coloring and pharmaceutical products, may become commercially interesting as starch raw materials. This work aimed to characterize the starch of two Curcuma species. The results revealed that the rhizomes of two species showed low dry matter and high starch contents. The amylose contents of the starches (22% C. longa and 21% C. zedoaria) were similar to potato starch. The results of microscopic analysis showed flat triangular shape and the size was 20-30 mum for two starches. The final viscosity of C longa was high (740 RVU) and the pasting temperature was 81 degreesC. In C. zedoaria the final viscosity was 427 RVU and the pasting temperature was 78 degreesC. These results differed from standard commercially used natural starches. (C) 2003 Elsevier Ltd. All rights reserved.
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The electric properties of (Sn, Ti)O-2 doped with 1.00 mol% CoO, 0.05 mol% Nb2O5 and xmol% La2O3 (0.25 less than or equal to x less than or equal to 1.00) have been studied. Sn0.25Ti0.75Co0.01Nb0.005 doped with 0.50 mol% La2O3 has a nonlinearity coefficient of 6. An increase in the concentration of La2O3 raised its resistivity, thereby altering the electric properties of the material. A thermal treatment in oxygen atmosphere increased the nonlinearity coefficient to a value of 9. (C) 2003 Elsevier B.V. All rights reserved.
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Pb1-xCaxTiO3 (0.10less than or equal toxless than or equal to0.40) thin films on Pt/Ti/SiO2/Si(100) substrates were prepared by the soft solution process and their characteristics were investigated as a function of the calcium content (x). The structural modifications in the films were studied using x-ray diffraction and micro-Raman scattering techniques. Lattice parameters calculated from x-ray data indicate a decrease in lattice tetragonality with the increasing content of calcium in these films. Raman spectra exhibited characteristic features of pure PbTiO3 thin films. Variations in the phonon mode wave numbers, especially those of lower wave numbers, of Pb1-xCaxTiO3 thin films as a function of the composition corroborate the decrease in tetragonality caused by the calcium doping. As the Ca content (x) increases from 0.10 to 0.40, the dielectric constant at room temperature abnormally increased at 1 kHz from 148 to 430. Also calcium substitution decreased the remanent polarization and coercive field from 28.0 to 5.3 muC/cm(2) and 124 to 58 kV/cm, respectively. These properties can be explained in terms of variations of phase transition (ferroelectric-paraelectric), resulting from the substitution the lead site of PbTiO(3)for the nonvolatile calcium. (C) 2002 American Institute of Physics.
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For the electric polarizability of a bound system in relativistic quantum theory, there are two definitions that have appeared in the literature. They differ depending on whether or not the vacuum background is included in the system. A recent confusion in this connection is clarified. © 1999 American Associations of Physics Teachers.
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This work deals with the effects of the series compensation on the electric power system for small-signal stability studies. Therefore, the system is modeled admitting the existence of the compensation and then, the equations are linearized and a linear model is obtained for a single machine-infinite bus power system with a compensator installed. The resulting model with nine defined constants is very similar to the Heffron & Phillips linear model widely used on the existent literature. Finally, simulations are executed for an example system, to analyze the behavior of these constants when loading the system. © 2004 IEEE.
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Replacing glass fibers with natural fibers in the automobile industry can yield economic, environmental and social benefits. This article evaluates the prospective environmental impacts of automobile applications of curauá fiber (Ananas erectifolius), which nearly equates the physical properties of glass fibers. The study identified economic and social advantages of applying curauá fiber composites in car parts. Besides costing 50% less than fiber glass, the use of curauá fibers can promote regional development in the Amazon region. In order to realize significant environmental benefits, however, the curauá-based composites would have to be lighter than their glass fiber-based counterparts. © 2006 Elsevier Ltd. All rights reserved.
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Outsourcing is related to the action which an organization deals with its suppliers through a kind of business contract where a specific activity or service has been hired to be made. The outsourcing of some activities has become a common practice in the industry, nowadays. It reduces costs, significantly, in the production process and, at the same time, adds some values to the business organization. However it is necessary to measure the performance of these activities. Data Envelopment Analysis (DEA) is a non-parametric method useful to measure comparative performance. It has a wide range of applications measuring comparative efficiency. The Analytic Hierarchy Process (AHP) is a multiple criteria decision-making method that uses hierarchic structures to represent a decision problem and then develops priorities for the alternatives based on the decision-maker's judgments. This paper presents an integrated application based on DEA and AHP to evaluate the efficiency of subcontracted companies in a Brazilian aerospace factory. © 2007 Springer-Verlag London Limited.
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The supply chain management, postponement and demand management operations are of strategic importance to the economic success of organizations because they directly influence the production process. The aim of this paper is to analyze the influence of the postponement in an enterprise production system with make-to-stock and with seasonal demand. The research method used was a case study, the instruments of data collection were semi-structured interviews, document analysis and site visits. The research is based on the following issues: Demand Management which can be understood as a practice that allows you to manage and coordinate the supply chain in reverse, in which consumers trigger actions for the delivery of products. The Supply Chain Management is able to allow the addition of value, exceeding the expectations of consumers, developing a relationship with suppliers and customer's win-win. The Postponement strategy must fit the characteristics of markets that require variety of customized products and services, lower cost and higher quality, aiming to support decision making. The production system make-to-stock shows enough interest to organizations that are operating in markets with high demand variability. © 2011 IEEE.