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Caracterización de los mecanismos cinéticos y de transferencia de momentum, calor y masa en un biorreactor de fermentación en medio sólido utilizando subproductos agroindustriales
Get PDFThe objective of this work was the development and implementation of experimental and numerical methodologies that would allow characterizing: hydrodynamics (fluid dynamics), heat and mass transfer under abiotic conditions in a packed tray bioreactor with wall cooling at bench scale. using agroindustrial by-products as substrate; and kinetics (biotic experiments) using Yarrowia lipolytica 2.2ab as microorganism. The characterization was evaluated at operating conditions of industrial interest: wall temperatures of 298.15 K - 318.15 K, initial moisture content of 6 - 60% and specific volumetric air flows of 1.25 - 62.50 Laire.kgss –1 .min–1 . In fluid dynamics, a model was developed that describes the velocity profiles of the fluid, the characterization of viscous and inertial resistances due to the interaction between the solid and the fluid in the regions of the core and the wall of the packed tray: two zones model (TZM). The TZM reduced the computation time (under the same computational conditions) by describing the same velocity profiles by 3000 to 3600% compared to a conventional hydrodynamic model (Navier-Stokes-Darcy-Forchheimer equations). In heat transfer, the parameters of effective thermal conductivity (keff) and the heat transfer coefficient in the wall (hw) in steady and transient state were estimated, this through experimental temperature data, incorporating the velocity profiles obtained with the TZM. The keff results obtained for the steady state are in a range from 1.24 x10-4 to 9.05 x10-4 W.m-1 .K-1 while for the transitory state it is in the range of 6.21 x10-1 to 2.11 x10-1 W.m-1 .K-1 ; on the other hand, hw in steady state ranges from 3.10 x101 to 7.501 x101 W.m-2 .K-1 , while for the transitory state it ranges from 6.57 x100 to 4.78 x102 W.m-2 .K-1 . The parameters were also determined considering an approximation of plug flow velocity, finding results with two orders of magnitude lower than that obtained with the velocity profiles of the TZM. In mass transfer, dispersion coefficients (Deff) were estimated with O2 concentration data. The Deff results ranged from 2.59 x10-3 to 5.28 x10-3 m2 .s-1 . The biotic analysis (kinetics) was characterized by determining the specific kinetic descriptors of the growth of the microorganism with experimental data of CO2 production and O2 consumption. Results were obtained for CO2max of 213.11 mgCO2.gms -1 , of h − 2 2 YCO O/ of 0.65 mgO2.mgCO2 -1 and mO2 of 1.51x10-3 mgO2 mgCO2 -1 h -1 . Finally, the individually obtained descriptors were integrated into a two-phase pseudoheterogeneous model (fluid and solid phase), which allows to characterize the kinetics and heat and mass transport phenomena. The simulations of the process show positive results, particularly in the concentration of CO2, O2 and H2O up to 12 hours after the start of the fermentation in solid medium, an area where the maximum production of CO2 is reached.Este trabajo tuvo como objetivo el desarrollo e implementación de metodologías experimentales y numéricas que permitieran caracterizar: la hidrodinámica (dinámica de fluidos), transferencia de calor y masa en condiciones abióticas en un biorreactor de charola empacado con enfriamiento en la pared a escala de banco utilizando como sustrato subproductos agroindustriales; y cinética (experimentos bióticos) utilizando Yarrowia lipolytica 2.2ab como microorganismo. La caracterización se evaluó a condiciones de operación de interés industrial: temperaturas de pared de 298.15 K – 318.15 K, contenido de humedad inicial de 6 – 60% y flujos volumétricos específicos de aire de 1.25 – 62.50 Laire.kgss ̄¹ .min ̄¹ . En la dinámica de fluidos se desarrolló un modelo que describe los perfiles de velocidad del fluido, la caracterización de resistencias viscosas e inerciales debido a la interacción entre el sólido y el fluido en las regiones del núcleo y la pared de la bandeja empaquetada: modelo de dos zonas (TZM por sus siglas en inglés). El TZM redujo el tiempo de cálculo (bajo las mismas condiciones de cómputo) al describir los mismos perfiles de velocidad en un 3000 a 3600 % en comparación con un modelo hidrodinámico convencional (ecuaciones de NavierStokes-Darcy-Forchheimer). En transferencia de calor se estimaron los parámetros de conductividad térmica efectiva (keff) y el coeficiente de transferencia de calor en la pared (hw) en estado estacionario y transitorio, esto mediante datos experimentales de temperatura, incorporando los perfiles de velocidad obtenidos con el TZM. Los resultados de keff obtenida para el estado estacionario se encuentra en un rango de 1.24 x10-4 a 9.05 x10-4 W.m ̄¹ . K ̄¹ mientras que para el estado transitorio se encuentra en el rango de 6.21 x10 ̄¹ a 2.11 x10-1 W.m ̄¹ . K ̄¹ ; por otra parte, hw en estado estacionario oscila desde 3.10 x101 a 7.501 x101 W.m ̄⁴ . K ̄¹ , mientras que para el estado transitorio oscila desde de 6.57 x100 a 4.78 x102 W.m ̄² .K ̄¹ . Los parámetros también se determinaron considerando una aproximación de velocidad de flujo pistón, encontrando resultados con dos órdenes de magnitud menores respecto a lo obtenido con los perfiles de velocidad del TZM.En transferencia de masa se estimaron los coeficientes de dispersión (Deff) con datos de concentración de O2. Los resultados Deff oscilaron entre 2.595 x 10 -3 y 5.286 x 10 -3 m2 .s -1 . El análisis biótico (cinética) se caracterizó determinando los descriptores cinéticos específicos del crecimiento del microorganismo con datos experimentales de producción de CO₂ y consumo de O₂. Se obtuvieron resultados de CO₂max de 213.11 mgCO2.gms -1 , de h − 2 2 YCO O/ de 0.65 mgO2.mgCO2 -1 y mO2 de 1.51x10-3 mgO2 mgCO₂ -1 h -1 . Finalmente se integraron los descriptores obtenidos individualmente a un modelo pseudoheterogéneo de dos fases (fase fluida y sólida) que permite caracterizar la cinética y los fenómenos de transporte de calor y masa. Las simulaciones del proceso presentan resultados positivos, particularmente en la concentración de CO₂, O₂ y H₂O hasta las 12 horas de iniciada la fermentación en medio sólido, zona donde se alcanza la máxima producción de CO₂
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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