1,720,955 research outputs found
Simulação off-design de um sistema ORC para recuperação de calor residual de um motor de combustão interna
Full text linkThe exhaust gases of an internal combustion engine (MCI) leave the equipment still with sufficient temperature to generate more electrical power, if a system is used for this purpose. Therefore, due to this scenario of the possibility of increasing the efficiency of the energy plant, thus reducing the emission of pollutants and fuel consumption, in this work a study was made on the use of the residual energy existing in the combustion gases of an engine diesel stationary internal combustion. For this, the ORC (Organic Rankine Cycle) was used, a thermodynamic cycle that uses an organic fluid as the working fluid. The analyzes are evaluated in three parts: 1) parametric analysis of an ORC system in permanent on-design regime (within the design conditions) to ascertain the influence of the variation of thermodynamic parameters, both in power and in the flow of working fluid , with the objective of determining the optimum point of operation of the cycle, determined “design point”; 2) parametric analysis of the same cycle, now in a permanent off-design regime (outside the design conditions), to check the influences when they are varied as a characteristic of the heat source (flow and temperature), now without varying the geometric design of the equipment constituents of the cycle, which brings the functioning of the cycle closer to reality; 3) an economic analysis of the feasibility of implantation for such an ORC plant, based on the model based on CEPCI. From the thermodynamic analyzes regarding the cycle efficiency, the system design was determined for a working fluid flow of 0.09 kg / s, evaporation and condensation pressure of 3.870 kPa and 25 kPa, respectively and with the exhaust gas (heat source) at 420 ° C and 0.1697 kg / s. From that point of operation, the geometries of the basic components of the ORC were determined: evaporator, turbine, condenser and pump. For the off-design simulations, performed with the aid of the ASPEN HYSYS® V.11 software, the evaporation pressure, the working fluid flow and the heat source inlet conditions were varied. From such simulations in different conditions, a minimum, average and maximum net power production of 8.56 kW, 15.59 kW and 26.29 kW, respectively, was observed, while in the design condition of 14.72 kW. The informative economic analysis that the initial investment for the implementation of the system is R 93.502,22 e o retorno financeiro e a taxa de retorno de chegam a uma média de 1,5 anos e 90%, respectivamente, a depender dos valores de juros tomados para o investimento. O estudo revela o sistema não requer grandes investimentos de capital e pode trazer retorno do investimento em pouco tempo e com ganhos satisfatórios a partir de então
Análise Técnica e Econômica do aproveitamento energético do Calor Residual em Motores de Combustão Interna usando o ORC.
Full text linkNeste trabalho de dissertação, fez-se uma pesquisa sobre o potencial de aproveitamento energético em um motor que utiliza um tipo de combustível fóssil (diesel). Foi realizado um estudo de caso, através de simulações no software HYSYS versão 8.6 da ASPENtech®, sobre o aproveitamento energético do calor descartado nos gases de exaustão de um motor do combustão interna (MCI). Foi realizado um estudo técnico-econômico com o objetivo de aumentar a eficiência na produção de energia elétrica e, assim, diminuir o consumo de combustível e as emissões de poluentes. Para tal, duas configurações de ORC (Organic Rankine Cycle) foram sugeridas, uma com o suprimento da água de condensação feito diretamente pela rede urbana de distribuição de água e a outra com um sistema de resfriamento para essa água, este último visa à implantação da planta ORC em locais onde há escassez ou dificuldade em obter água. Ambos os sistemas simulados conseguiram aumentar em até, aproximadamente, 20% a produção de eletricidade, com uma produção ligeiramente maior de energia pelo sistema que usa água da rede urbana. A análise econômica inclui um modelo econômico baseado no CEPCI (Chemical Egineering Plant Cost Index) e mostrou que o retorno financeiro na implantação do sistema ORC pode acontecer em no mínimo seis anos e três meses. Assim, conclui-se que o sistema ORC pode ser instalado em qualquer região, sem que haja muitas perdas em seu rendimento, e é uma solução adequada, tecnologicamente, para aproveitar o calor rejeitado nos gases de escape de um MCI, mas que ainda necessita de incentivos dos governos para que seja amplamente aplicada
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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