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Modeling of the deterioration and distributions of temperature and moisture content of stored grains in bin with aeration
No full textEste trabalho teve como objetivo geral a modelagem da distribuição de ar, de transferência de calor e de massa e da deterioração em um sistema constituído de grãos de milho armazenados em um silo metálico provido de aeração. Os objetivos específicos foram: (a) determinar, experimentalmente, os parâmetros (condutividade térmica, calor específico, difusividade térmica e massa específica) envolvidos nos modelos; (b) desenvolver, utilizando a técnica de elementos finitos, um modelo computacional, bidimensional, para predizer a distribuição de ar no interior de uma massa de grãos sob aeração; (c) desenvolver um modelo bidimensional para determinação da distribuição de temperatura e de teor de umidade no sistema durante o processo de aeração usando os resultados obtidos pelo modelo de distribuição de ar; (d) implementar um modelo para determinação da deterioração da massa de grãos utilizando os resultados obtidos pelo modelo de distribuição de temperatura e umidade e (e) obter, experimentalmente, as distribuições de temperatura e de teor de umidade, em uma massa de grãos de milho armazenada em um silo metálico cilíndrico, dotado de aeração visando à validação dos modelos de distribuição de ar e da transferência de calor e de massa. Equacionou-se a condutividade térmica de amostras de milho (w m -1 °C -1 ), com teor de umidade (U), na faixa de 11,3 a 18,4% b.u., como: k = 0,0024 U+0,127 ± 0,004302; o calor específico de amostras de milho (kJ kg -1 °C -1 ), com teor de umidade faixa de 11,3 a 18,4% b.u., como: c p = 0,0636 U + 1,0662. No modelo de distribuição de ar, o sistema modelado, consistiu de uma massa de grãos de milho (13% b.u.) contida, até uma altura de 1,6 m, em um silo metálico cilíndrico de 1,8 m de raio. O sistema foi considerado simétrico em relação ao eixo longitudinal central do silo, eixo Y. Escoamento de ar foi introduzido na parte inferior do sistema, através de uma abertura simulando um duto circular perfurado (largura de 0,2 m). A técnica de elementos finitos foi utilizada na modelagem da distribuição de ar do no silo. O sistema foi discretizado em 1550 elementos retangulares, totalizando 1632 nós. Foi considerado, nas simulações, que o produto oferece resistências ao escoamento do ar nas direções horizontal e vertical. O modelo para distribuição de ar no silo foi validado por meio de experimentos usando-se condições similares às simuladas e um fluxo de ar de 0,0157 m 3 s -1 m -2 de chapa perfurada. O sistema modelado (distribuição de ar), supracitado, foi utilizado no modelo de distribuição de temperatura, teor de umidade e deterioração dos grãos durante o processo de aeração. Desenvolveu- se um software, utilizando a linguagem Basic, para simular as variações de temperatura, teor de umidade e deterioração dos grãos de milho armazenados em silo metálicos cilíndricos durante o processo de aeração. O programa é composto de uma seção de entrada de dados e de três rotinas principais: (a) rotina para determinação da vazão de ar que aflue ou eflui de cada face dos elementos; (b) rotina para percorrer a malha de elementos; e (c) rotina para simulação das variações de temperatura, teor de umidade e deterioração dos grãos durante o processo de aeração. Visando, a validação do modelo de distribuição de temperatura e de teor de umidade, desenvolvido neste trabalho, grãos de milho (Zea mays L.), adquiridos pelo Centro de Produção da Universidade Federal de Viçosa, (safra 2000/2001), foram armazenados em um silo metálico cilíndrico, similar ao usado nas simulações. O lote continha grãos de diferentes variedades. Termopares "tipo T" (cobre-constantan) foram posicionados dentro do silo, em 11 pontos. Os valores das variáveis pertinentes ao experimento foram registrados com o auxílio de um sistema automático de aquisição de dados. Dois testes usando aeração contínua nos grãos foram executados, sendo que, antes de iniciar cada teste, a massa de grãos foi aquecida até, aproximadamente, 28 oC. Cada teste de aeração teve duração de 96 h, e durante os testes foram realizadas amostragens diárias em diversos pontos da massa de grãos, para determinação do teor de umidade. A distribuição de ar, proveniente das simulações, indicou a existência de zonas de baixa velocidade na massa de grãos, situadas na sua parte inferior, próximas ao centro do silo e à sua parede. As velocidades do ar na superfície da massa de grãos, simuladas e experimentais, tenderam a serem uniformes. A utilização da técnica de elementos finitos para a predição da distribuição do fluxo de ar, em silos providos de sistema de aeração, mostrou-se satisfatória e envolveu um erro relativo médio de 6,9%. O modelo de distribuição de temperatura, teor de umidade e deterioração dos grãos armazenados em silos metálicos cilíndricos, durante o processo de aeração, mostrou-se adequado. Os erros médios envolvidos na predição da temperatura e do teor de umidade foram inferiores a 9 e 6%, respectivamente. A deterioração média dos grãos, estimada pelo modelo, foi de 2,8 x10 -4 %.The general objective of this work was the modeling of the air distribution, heat and of mass transfer and deterioration in corn grains stored at a metallic bin with aeration. The specific objectives were: (a) to determine experimentally parameters involved in the models (thermal conductivity, specific heat, thermal diffusivity and bulk density); (b) to develop a finite element computational model to predict the air distribution in grains stored in a bin submitted to aeration process; (c) to develop a two-dimensional model for determination of temperature and moisture content distributions in the system during the aeration process using the results from the air distribution model; (d) to implement a model for determination of the deterioration in a mass of grains using the results obtained by the temperature and moisture content distribution model and (e) to obtain experimentally the temperature and moisture content distributions in corn grains stored at a cylindrical metallic bin with aeration seeking the validation of the models. Thermal conductivity (W m -1 °C -1 ) and specific heat (kJ kg -1 °C -1 ) of corn samples can be expressed as a function of moisture content (U, in the range of 11.3 to 18.4% w.b.) respectively by the equations: k = 0.0024 U+0.127 ± 0.004302 and c p = 0.0636 U + 1.0662. Air distribution was obtained for a system composed of a mass of corn grains (height of 1.6 m) at 13% w.b. located in a cylindrical metallic bin of 3.6 m of diameter. The system was considered symmetrical in relation to the central longitudinal axis of the bin. Airflow was introduced in the system floor through an opening simulating a perforated circular duct (width of 0.2 m). The finite element technique was used in the two-dimensional modeling of the air distribution in the bin and the system was divided in 1550 rectangular elements (1632 nodes). In the simulations it was considered that the product offers two type of airflow resistances: in the horizontal and vertical directions. The air distribution model was validated through experiments using similar conditions to the simulated ones and an airflow of 0.0157 m 3 s -1 m -2 through a perforated circular duct. The air distribution results were used as input in the model of temperature and moisture content distributions and deterioration of the grains during the aeration process. A software (Basic language) was developed to simulate temperature and moisture content variations and deterioration of the corn grains stored at cylindrical metallic bin during the aeration process. The program is composed of an input data section and three main routines: (a) routine for determination of the inlet and outlet airflow through each element face; (b) routine to travel the element mesh and (c) routine for simulation of the temperature, moisture content and deterioration of the grains during the aeration process. The temperature and moisture content distribution model was validated using experimental data. The experiments were conducted using corn grains (Zea mays L.) from the Production Center of the Universidade Federal de Viçosa (crop 2000/2001) stored at a cylindrical metallic bin similar to the used in the simulations. Termocouples " type T " (copper-constantan) were positioned inside of the bin at eleven locations. The mass of grains was submitted to a two continuous aeration tests and the values of the pertinent experimental variables were registered with the aid of a data acquisition system. The mass of grains was heated up to approximately 28 oC before each aeration test. The product in each test was aerated during 96 h and samples of the product were removed daily during the aeration for moisture content determinations. The simulated air distribution indicated the existence of low speed zones in the mass of grains located at the base of the bin (close to the center and to the wall of the bin). The simulated and experimental air velocities indicate an air distribution uniform on the surface of the mass of grains. The use of the finite element technique for airflow distribution predictions in a mass of grains stored in a bin during aeration process was shown satisfactory and it involved a average relative error of 6.9%. The temperature and moisture content distributions and deterioration model implemented in this work predicted adequately the values of temperature and moisture content in a mass of grains stored at cylindrical metallic bin during the aeration process. The average relative errors involved in the temperature and moisture content predictions were inferior to 9 and 6%, respectively. The mean deterioration value of the grains estimated using the model was of 2.8 x10 -4 %.Conselho Nacional de Desenvolvimento Científico e Tecnológic
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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