131 resultados para centrifugal cleaner
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The use of polymeric materials has grown in recent years due to its high durability features, atoxicity, shaping versatility and environment resistance. However, while these features represent good advantages to several industry sectors, it results in one of the most serious environmental problems of contemporary society: the rising accumulation of these material, mainly due to the inadequate disposal of waste. Meanwhile, in order to minimize this problem, some mitigation techniques comes up (arises), among which the use of biodegradable polymers has been gaining attention. Because of their easily action of microorganisms, such material degrade more rapidly, becoming integrated to nature. Furthermore, due to the fact of biodegradation is a natural process, occurring through the action if micro-organisms in the environment itself, it is considered the “cleaner” alternative found so far to plastic components reincorporation in the nature. Among the micro-organisms capable of biodegradation process are the filamentous fungi. These micro-organisms have many advantages over the others, the major one being the capacity to produce a range of enzymes capable of degrading different materials. In this context, the present review made it possible to see the importance of this process as an agent of environmental preservation, suggest the use of blends to minimize the problems of cost and flexibility of biodegradable polymeric materials, as well as noting the lack of studies related to this subject nowadays
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This study is about a heating line that uses thermal oil. It is located in a facility that produces interlayers used in cars windshields. A plastic resin is melted and is sent to a matrix called DIE where the interlayers are produced. The DIE needs to receive heat from the circulation of thermal oil in four different regions of its interior, to ensure the correct thickness of the interlayer. The thermal energy is provided by electric heaters and the flow of thermal oil is impelled by four mechanically sealed centrifugal pumps (one per region). The key point of this study is the fact that these four pumps of the system have reported successive failures in the mechanical seals. Apparently, a poorly designed project has burdened the system intermittently. The pumps operation condition is located in a region of low efficiency, according to the characteristic curves. This fact is the source of the noticeable reduced time between failures. Changes in the configuration of the facility and in the number of pumps will be proposed, aiming to achieve higher operational efficiency. The proposals will be mathematically analyzed according to the Hydraulic Institute criteria. At the same time, we will also keep focus on an in-depth study of a heating system structure, starting with a detailed approach for each component and discussion about its real need and economic viability. At the end of this paper it is shown that the gain in efficiency achieved with the new proposed configuration reflects not only in the reduction of maintenance costs, but also a potential improvement in energy efficiency. It is shown that these two aspects are closely related and together form the basis for the design of a reliable and efficient pumping system
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This research has as main objective the analysis of the auto industry has done to reduce disposal of solid waste in its production process as much as to facilitate the recycling of cars after they complete their life cycle. Despite the auto industry is not one of the most polluting in terms of its production process, it produces a good that is causing major pollution. In despite of the great current concern in seeking to reduce the emissions of pollutants by vehicles, as important as the quest for cleaner fuels is the study of how to dispose of old cars. Even if the car production does not increase significantly each year in relative terms, we must consider the fleet of used cars that still circulates in the world. Ending the mammoth “cemeteries” of automobiles, however, it is not so easy, even because the car is composed of various materials, which in many cases are not easily separable. In addition to an overview, the research seeks to examine the possible advances in Brazil related to the process of auto recycling
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In Brazil, The power generation has always depended on the rivers, in other words, there are moments that the power generation can vary, which can cause variations in energy supply and even blackout according to the level of water in the reservoirs of the hydroelectric plants. For this reason, many options has been studied, like our example, which is about a combined cycle power plant in Canas. The use of combined cycle is interesting from the point o view of energy, because its efficiency is between 50 and 60%, and from the point of view of environment, because it can burn natural gas, which is cleaner than coal, it reduces the emission of gases that influence on the greenhouse effect. This work aims to perform a technical analysis of a case study of a power plant proposed to be built in Canas by the AES/AES Tietê Group. For the analysis will be used the commercial software GateCycle 6.0.0 from GE, this software has the power of simulating power generation cycles (nuclear, combined, etc.). The energy department of UNESP has the license, which makes possible the academic use of this tool. Two combined cycles were simulated, one using one pressure level HRSG, and another one closer to the real power plant, which is a combined cycle with a three pressure level HRSG. The results were close to expected, for the combined cycle with one pressure HRSG the power was 513,9 MW and a efficiency of 53,27%, in the case with the three pressure level HRSG the power was 517,1 MW and a efficiency of 53,5%. We conclude that the software requires that the user must have the knowledge about the subjects involved in the use of GateCycle in problems resolutions
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Pós-graduação em Ciência Florestal - FCA
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Pós-graduação em Agronomia (Ciência do Solo) - FCAV
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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)
Understanding the genesis of green supply chain management: lessons from leading Brazilian companies
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This work discusses the internal structuring processes of leading companies when adopting green supply chain management (GSCM) practices. A multiple case study approach was adopted as the research methodology, with four large Brazilian companies that are leaders in their market segments. The introduction of green products is a key step towards initiating concern for the environment among suppliers and customers. This study's results show the importance of having green teams, a dedicated functional area, and/or green jobs that support the discussion of environmental management among a business and beyond. The practical results of this study offer new insights into the behavior of companies that are adopting GSCM practices, thereby generating new evidence for the extension of GSCM theory. (C) 2014 Elsevier Ltd. All rights reserved.
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The goal of this study is to present and test a conceptual framework that describes the technical aspects (TA), human/organizational aspects (HOA) of the adoption of green product development (GPD) practices and the effect of these practices on firms'environmental (EP), operational (OP) and market performance (MP). To this end, after reviewing the literature on these themes, a conceptual framework with 5 hypotheses is proposed. These hypotheses were tested on 62 Brazilian companies through structural equation modeling using SmartPLS 2.0M3. The main results of this study are as follows: (a) in general, the proposed framework obtained adequate goodness of fit statistics (GoF); (b) technological factors are shown to have an influence on the adoption of GPD practices, and those practices are related to company EP, OP and MP, thus confirming 4 hypotheses of the study; and (c) one of the study's hypotheses is not validated, indicating that the relationship of human/organizational aspects to GPD must be further analyzed. This work extends the literature because: (a) the conceptual framework tested in this study establishes several concepts that have been only partially tested in the previous literature; (b) this work presents evidence about Brazil, where the themes addressed herein have not been yet been thoroughly investigated; and (c) the non-validation of the hypothesis regarding the relationship between human/ organizational aspects with respect to the adoption of product-related environmental practices requires attention. (C) 2014 Elsevier Ltd. All rights reserved.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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In epidemiological surveys, the evaluation of soil contamination by Toxocara canis eggs requires a quick and easy method for the isolation of parasite eggs from soil samples. The efficiency of flotation methods is influenced by sample size, soil texture, degree of soil contamination, pretreatment, flotation solutions and time of flotation. This investigation was designed to evaluate the influence of soil texture in the recovery of T. canis eggs with the centrifugal flotation technique of Dada (Dada, B.J.O., 1979. A new technique for the recovery of Toxocara eggs from soil. J. Helminthol., 53: 141-144). Four types of soil (clay silt, sandy, silty clay and sand) were artificially contaminated with T. canis eggs (200 eggs per gram). Zinc sulphate (specific gravity 1.20) and sodium dichromate (specific gravity 1.35) were used as flotation solutions. Twenty replicated examinations were performed for each type of soil and flotation solution. There was a statistically significant difference in the results depending on soil type. The highest recovery percentages were observed in soils rich in sand (62.5% for sand and 38.0% for sandy soil). Differences were also observed with different flotation solutions. Sodium dichromate solution was more efficient for recovering T. canis eggs, regardless of the soil texture. © 1994.
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Most work on supersingular potentials has focused on the study of the ground state. In this paper, a global analysis of the ground and excited states for the successive values of the orbital angular momentum of the supersingular plus quadratic potential is carried out, making use of centrifugal plus quadratic potential eigenfunction bases. First, the radially nodeless states are variationally analyzed for each value of the orbital angular momentum using the corresponding functions of the bases; the output includes the centrifugal and frequency parameters of the auxiliary potentials and their eigenfunction bases. In the second stage, these bases are used to construct the matrix representation of the Hamiltonian of the system, and from its diagonalization the energy eigenvalues and eigenvectors of the successive states are obtained. The systematics of the accuracy and convergence of the overall results are discussed with emphasis on the dependence on the intensity of the supersingular part of the potential and on the orbital angular momentum.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Conselho Nacional de Desevolvimento Científico e Tecnológico (CNPq)