596 resultados para tuna
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Uma análise de dados publicados sobre dietas de aves marinhas oceânicas mostra a predominância de cefalópodes musculares e de distribuição mais superficial nas camadas oceânicas, mas também são importantes as espécies gelatinosas e amoniacais restritas a camadas abaixo dos 300 m da superfície. A princípio, não deveria se esperar que cefalópodes de profundidade fossem considerados presas comuns de aves marinhas oceânicas como reportados por muitos autores. É proposto neste estudo que uma fonte indireta, importante e de fácil obtenção, surgiu com o início das atividades dos barcos atuneiros que operam com espinhel. O hábito de ingerir restos de vísceras de peixes capturados em barcos espinheleiros pode explicar as prováveis conclusões equivocadas de que cefalópodes de profundidade são presas naturais de aves marinhas oceânicas.
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Diet composition of the blue marlin, Makaira nigricans, from the southwestern equatorial Atlantic Ocean was analyzed between October 2004 and November 2005. In the 226 stomachs of fish ranging between 100 and 311 cm lower jaw -fork length (LJFL), 44 items were identified, including 31 fishes and 13 cephalopods. Seventy stomachs were empty (23.6 %). M. nigricans fed preferentially on heavy and muscular scombrid fishes especially upon the skipjack tuna, Katsuwonus pelamis (Linnaeus, 1758), probably to sustain their high metabolism, and on a variety of other items composed mainly by epipelagic species of fish and cephalopods.
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This article presents an thermoeconomic analysis of cogeneration plants, applied as a rational technique to produce electric power and saturated steam. The aim of this new methodology is the minimum exergetic manufacturing cost (EMC), based on the Second Law of Thermodynamics. The decision variables selected for the optimization are the pressure and the temperature of the steam leaving the boiler in the case of using steam turbine, and the pressure ratio, turbine exhaust temperature and mass flow in the case of using gas turbines. The equations for calculating the capital costs of the components and products are formulated as a function of these decision variables. An application of the method using real data of a multinational chemical industry located in São Paulo state is presented. The conditions which establish the minimum cost are presented as finals conclusions.
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In this paper, a thermoeconomic functional analysis method based on the Second Law of Thermodynamics and applied to analyze four cogeneration systems is presented. The objective of the developed technique is to minimize the operating costs of the cogeneration plant, namely exergetic production cost (EPC), assuming fixed rates of electricity production and process steam in exergy base. In this study a comparison is made between the same four configurations of part I. The cogeneration system consisting of a gas turbine with a heat recovery steam generator, without supplementary firing, has the lowest EPC. (C) 2004 Published by Elsevier Ltd.
Ecological impacts from syngas burning in internal combustion engine: Technical and economic aspects
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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This work aims with an approach for cogeneration plants evaluation based on thermoeconomic functional diagram analysis. The second law of thermodynamics is used to develop a methodology to analyse cogeneration systems, based on exergoeconomics evaluation. The thermoeconomic optimisation method developed is applied to allow a better configuration of the cogeneration plant associated to a university hospital. Also ecological efficiency is evaluated. The method was efficient and contributes for thermoeconomics modelling and analysis and can be applied to any sort of thermal system, especially those with combined heat and power in thermal parity. (C) 2012 Elsevier Ltd. All rights reserved.
Resumo:
This work presents a thermoeconomic optimization methodology for the analysis and design of energy systems. This methodology involves economic aspects related to the exergy conception, in order to develop a tool to assist the equipment selection, operation mode choice as well as to optimize the thermal plants design. It also presents the concepts related to exergy in a general scope and in thermoeconomics which combines the thermal sciences principles (thermodynamics, heat transfer, and fluid mechanics) and the economic engineering in order to rationalize energy systems investment decisions, development and operation. Even in this paper, it develops a thermoeconomic methodology through the use of a simple mathematical model, involving thermodynamics parameters and costs evaluation, also defining the objective function as the exergetic production cost. The optimization problem evaluation is developed for two energy systems. First is applied to a steam compression refrigeration system and then to a cogeneration system using backpressure steam turbine. (C) 2010 Elsevier Ltd. All rights reserved.
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Cover crops are used for the purpose of land cover in order to improve the physical, chemical and biological properties of cultivated soils and improve the sustainability of grain production. The objective of this study was to evaluate the effect of different cover crops and the sowing of beans on the characteristics of three cultivars of commom bean in no tillage sistem. The research was develop in Fazenda de Ensino Pesquisa da Faculdade de Engenharia-UNESP-Campus de Ilha Solteira. The experimental design was completely randomized blocks and treatments were arranged in bands in 5x2x3 factorial design with four replications. The treatments consisted of cover crops (millet, jack bean, sunn hemp, velvet bean and fallow), sowing of beans (Perola, IAC Tuna, Carioca Precoce) grown in two years. Were evaluated: the final stand of plants, number of pods per plant, number of seeds per pod and per plant, weight of 100 seeds and seed yield. The cover crops sunn hemp and millet showed higher amount of fresh biomass in both years of cultivation, being recommended for our region. Occurring variations in the productivity of seeds depending on the years of cultivation, but the IAC Tuna was more stable in the variables analyzed.
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Effect of green manure and sowing date on the productivity of bean no-tillage in the Cerrado region. Green manure and sowing date are two important factors that influence the productivity of cultivars. The objective of this study was to evaluate the production of biomass from different vegetation covers (millet, sorghum and Brachiaria brizantha) and the accumulation of nutrients and their effects on the bean cultivars (Pearl, IAC Tuna and Carioca Precoce) at different sowing dates (6/22 and 7/6). The experiment was conducted at the experimental area of the Universidade Estadual Paulista - Unesp, located in Selviria, Mato Grosso do Sul State, in the 2006/2007 agricultural year. The randomized blocks design was used with four replications, and the evaluations of the coverage were: the biomass of fresh and dry matter and nutrients accumulated in plants; for the beans: cycle, final stand, number of pods/plant, number of seeds per pod, mass of 100 seeds, and productivity. It was observed that millet and sorghum showed higher productivity of fresh and dry mass, and accumulate greater quantity of nutrients in straw; the time most suitable for sowing was in June, and the late sowing of cv. Carioca Precoce did not affect their productivity, the use of Brachiaria brizantha straw in coverage provided better conditions for productivity in the bean no-tillage system.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Three Latin American oilseeds obtained from native fruits: nopal (tuna) (Opuntia ficus-indica), cherimoya (chirimoya) (Annona cherimola), and papaya, Chilean variety (Carica pubescens or C. candamarcensis) were studied for their fatty acid composition and bioactive compounds, such as tocols and phytosterols, looking for new sources of special oilseeds for this region. The results indicated that each species represents an interesting possibility. Nopal oilseed is a good source of linoleic acid (62%), with a good balance between SFA and MUFA (1: 1.3). Cherimoya oilseed presents quite a different composition, with 24% SFA, 43% MUFA and 33% PUFA. Palmitic and stearic acids (15% and 7.6%, respectively) are the main SFA. A good balance between oleic acid (42.7%) and linoleic acid (31%) was observed. Papaya oilseed is a highly MUFA oil (72% with 71% oleic acid), with a very interesting composition, according to the new nutritional and technological recommendations.With respect to bioactive compounds, the main tocol in these three oilseeds was gamma-tocopherol, with 136, 300 and 317 mg/kg for cherimoya, papaya and nopal oilseeds, respectively. According to the total tocol content, papaya oilseed presented the highest value with 384 mg/kg. The total amount and distribution of phytosterols was different, with values of 3092, 3554 and 5474 mg/kg for nopal, cherimoya and papaya oilseeds, respectively, with beta-sitosterol forming 47.6%, 65.0 % and 78.7% of the total phytosterol fractions, respectively. From the results obtained, Chilean papaya oilseed can be considered as a very promising new source of special plant oil for different applications, followed by cherimoya and nopal oilseeds.
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The present paper describes the use of sugar cane bagasse as solid phase extractor for cadmium determination after complexation of the analyte with ammonium diethyldithiophosphate (ADDP) and sorption of the Cd-DDP complexes on the solid support. The concomitants were separated using a flow injection analysis (FIA) system coupled to flame atomic absorption spectrometry (FAAS) for determination. The main parameters such as ADDP concentration, acid medium, flow rate, reaction coil length, and reaction time were investigated.The results obtained with HNO3 showed good accuracy and precision. The enhancement factor was 20.5 times for a 120-second preconcentration time, and the analytical frequency was 25 determinations per hour. The calibration curve was linear over the concentration range of 1-40 mu g L-1 Cd with a LOD of 0.697 mu g L-1 Cd and a relative standard deviation of 0.96% after 12 successive measurements of 30 mu g L-1 Cd.The proposed method was evaluated for the FIA-FAAS analysis of certified reference materials (tomato leaves, spinach leaves, and bovine liver) and Cd-spiked foods (shrimp, sardine, tuna, chicken liver and bovine liver). Good recoveries (80.0-97.1%) for the Cd-spiked samples and certified reference materials were obtained. The results of bagasse-packed minicolumns were compared with Si-C,8 packed minicolumns. The F-test was applied between Si-C-18/Bagasse minicolumns, Si-C-18/certified values, and bagasse/certified values. It was found that the results were in agreement with the certified values at a 95% confidence level.
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This article presents a thermoeconomic analysis of cogeneration plants, applied as a rational technique to produce electric power and saturated steam. The aim of this new methodology is the minimum Exergetic Production Cost (EPC), based on the Second Law of Thermodynamics. The variables selected for the optimization are the pressure and the temperature of the steam leaving the boiler in the case of using steam turbine, and the pressure ratio, turbine exhaust temperature and mass flow in the case of using gas turbines. The equations for calculating the capital costs of the components and products are formulated as a function of these decision variables. An application of the method using real data of a multinational chemical industry located in São Paulo state is presented. The conditions which establish the minimum cost are presented as final output. (C) 2003 Elsevier Ltd. All rights reserved.
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The growing demand for electrical power and the limited capital invested to provide this power is forcing countries like Brazil to search for new alternatives for electrical power generation. The purpose of this paper is to present a technical and economic study on a 15 kW solar plant installed in an isolated community, highlighting the importance of the need for financial subsidy from the government. It evaluates the importance of parameters such as the annual interest rate, specific investment, the marginal cost of expanding the electrical power supply and the government subsidy on amortization time of capital invested. © 2012 Elsevier Ltd All rights reserved.
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This work developed a methodology that uses the thermoeconomic functional diagram applied for allocating the cost of products produced by a biodiesel plant. The first part of this work discusses some definitions of exergy and thermoeconomy, with a detailed description of the biodiesel plant studied, identification of the system functions through Physical Diagram, calculation of the irreversibilities of the plant, construction of the Thermoeconomic Functional Diagram and determination of the expressions for the plant's exergetic functions. In order to calculate the exergetic increments and the physical exergy of certain flows in each step, the Chemical Engineering Simulation Software HYSYS 3.2 was used. The equipments that have the highest irreversibilities in the plant were identified after the exergy calculation. It was also found that the lowest irreversibility in the system refers to the process with a molar ratio of 6:1 and a reaction temperature of 60 °C in the transesterification process. In the second part of this work (Part II), it was calculated the thermoeconomic cost of producing biodiesel and related products, including the costs of carbon credits for the CO2 that is not released into the atmosphere, when a percentage of biodiesel is added to the petroleum diesel used by Brazil's internal diesel fleet (case study). © 2013 Elsevier Ltd. All rights reserved.