1,720,996 research outputs found
STOCHASTIC FRACTURED ROCK FACIES FOR GROUNDWATER FLOW MODELING
Get PDFEste artículo presenta los resultados de una simulación de flujo de agua subterránea en rocas fracturadas. Se emplea un enfoque estocástico (modelo estocástico equivalente en medio poroso fracturado) para construir el modelo conceptual y para usar este último en la roca de baja permeabilidad encontrada en el sitio elegido como caso de estudio (Olkiluoto, Finlandia). La roca que se investiga se encuentra localizada alrededor de un grupo de pozos de sondeo y cubre un área de algunas hectáreas. Las mediciones de campo de pruebas de interferencia hidráulica se utilizan para calibrar el modelo de flujo de agua subterránea. Múltiples combinaciones de facies estocásticos se consideran para evaluar el impacto de la distribución y del número de facies en las cargas hidráulicas y en los caudales. Este estudio cuantifica la variabilidad de los resultados numéricos, lo cual es importante para el análisis de la incertidumbre en los sistemas hidrogeológicos. Por otra parte, este estudio muestra que el modelo conceptual de facies estocásticos es una alternativa adecuada a los modelos conceptuales de redes de fracturas discretas
Propuesta de instalación geotérmica somera a partir de bombas de calor para la climatización de espacios en la Universidad EIA.
No full text75 páginasRESUMEN: La energía geotérmica corresponde al calor generado por núcleo terrestre, el cual puede
utilizarse de distintas formas según el grado de entalpía en el que se encuentre. Esta se
denomina somera o superficial cuando se encuentra entre los primeros 400 metros de
profundidad en la corteza terrestre con temperaturas de hasta 30 °C, las cuales pueden ser
utilizadas en procesos domésticos, agrícolas e industriales. Uno de los principales usos
que se le da a esta energía corresponde a la implementación de sistemas de climatización
de espacios a partir de suelos y acuíferos que permitan aportar y/o dispersar calor, siendo
este utilizado a través de una bomba de calor que genera calefacción o refrigeración de un
espacio específico. Existen tres tipos de instalaciones geotérmicas, principalmente, que se
clasifican según el medio que utilizan para aportar el calor: acopladas al suelo, con agua
subterránea o con agua superficial. Para la instalación de este tipo de sistemas deben
tenerse en cuenta factores de normatividad vigentes según las prácticas como el uso de
agua subterránea o las perforaciones, por lo que se listaron algunas recomendaciones y
análisis del estado legal de la geotermia somera en Colombia.
A partir de una recopilación bibliográfica se documentaron diversos conceptos y
metodologías útiles para el desarrollo de las etapas preliminares de planeación y diseño de
un sistema con Bomba de Calor Geotérmica (BCG). Se propuso un prototipo de sistema de
refrigeración para un salón de computadores de la Universidad EIA, con una carga térmica
calculada a través de hojas de cálculo de Excel dando un resultado aproximado de 9,65
kW. La bomba de calor seleccionada para suplir la demanda pertenece a la empresa
Ecoforest, con una potencia de 1-9kW. El sistema intercambiador de calor propuesto
corresponde a un sistema cerrado horizontal acoplado al subsuelo tipo slinky para el que
se calculó una longitud aproximada de tuberías de 1.301 m, configurado en tres o seis
trincheras con un área total requerida para la instalación de 911 y 952 m2
respectivamente.
Estos resultados permitieron observar las condiciones iniciales para la continuación de un
proyecto de climatización en la Universidad EIA que utilice la geotermia somera, y se
presentaron otras alternativas para los sistemas intercambiadores y consideraciones para
proyectos futuros.ABSTRACT: Geothermal energy corresponds to the heat generated by the Earth's core, which can be
used in different ways depending on its the degree of enthalpy. It is called shallow or
superficial resource when it's found between the first 400 meters deep in the Earth's crust
with temperatures up to 30 °C, and is normally used in domestic, agricultural, and industrial
processes. One of the main uses that is given to this energy corresponds to the
implementation of Heating, Ventilation and Air Conditioning (HVAC) systems, using the
ground or groundwater as a sink or source of heat. There are mainly three types of
geothermal systems, which are classified according to the medium used to exchange the
heat: ground, groundwater or surface water. For the installation of this type of systems,
current regulatory factors must be considered according to practices such as the direct use
of groundwater or drilling; therefore some recommendations and analysis of the legal status
of shallow geothermal energy in Colombia were listed.
From a bibliographic compilation, various concepts and useful methodologies were
documented for the development of the preliminary stages of planning and designing a
system with geothermal heat pump. A prototype of a cooling system for a computer room in
the EIA University was proposed, with a thermal load calculated through Excel spreadsheets
giving an approximate result of 9.65 kW. The heat pump selected to meet the demand
belongs to "Ecoforest", with a power of 1-9kW. The proposed heat exchanger system
corresponds to a ground-coupled horizontal closed-loop slinky-type system, with an
approximate calculated length of pipes of 1,301 m, installed in a configuration of three or six
trenches with a total area required of 911 or 952 m2
, respectively.
These results provide the initial conditions for the continuation of a HVAC project at the EIA
University using shallow geothermal energy, introducing other possibilities for different heat
exchangers as suggestions and considerations for similar future projects.PregradoIngeniero(a) Geológico(a
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
STOCHASTIC FRACTURED ROCK FACIES FOR GROUNDWATER FLOW MODELING
No full textThis paper presents simulation results of groundwater flow in fractured rocks. A stochastic approach is employed to build the conceptual model, a stochastic Equivalent Porous Medium fractured rock facies model, for the low-permeability bedrock found at Olkiluoto (Finland), which is the site chosen for the case-study. The volume of rock investigated is located around a cluster of boreholes and it covers an area of 160000 square meters. Field measurements during hydraulic interference tests are used to calibrate the groundwater flow model. Multiple stochastic facies realizations are considered to evaluate the impact of distribution and number of facies on simulated hydraulic heads and flow rates. This study quantifies the variability of numerical results, which is important for uncertainty analysis of hydrogeologic systems. Moreover, it shows that the stochastic facies conceptual model is a suitable alternative to discrete fracture network conceptual models
Integration of 3D geological and numerical models based on tetrahedral meshes for hydrogeological simulations in fractured porous media
No full textUne nouvelle approche de modélisation des milieux géologiques fracturés représentés par un modèle conceptuel de fractures discrètes et déterministes est présentée dans cette thèse. L'objectif principal de l'étude est de reproduire l'hétérogénéité et la complexité des milieux poreux fracturés dans un modèle géométrique tridimensionnel afin d'effectuer des simulations numériques dans le but d'améliorer les capacités de modélisation en hydrogéologie. Ceci est réalisé à travers le couplage entre une plateforme de modélisation géologique (GOCAD) et un code numérique (HydroGeoSphere). Les principaux défis à relever sont: la représentation géométrique du réseau de fractures, la sélection d'un maillage approprié pour la discrétisation spatiale du domaine de simulation et l'adaptation du code numérique à ce maillage. La nouvelle approche est basée sur une première phase de modélisation géologique 3D, suivie par la génération d'un maillage tétraédrique 3D et par la simulation numérique de l'écoulement souterrain en conditions saturées et du transport de solutés. En général, le maillage tétraédrique s'avère plus adéquat que les maillages de blocs ou de prismes pour discrétiser les geometries complexes telles que les milieux fracturés. De plus, une définition alternative du maillage "dual", qui est essentiel pour appliquer la méthode numérique élément finis - volume de contrôle utilisée par HydroGeoSphere, est analysée et intégrée dans le code numérique. Le code numérique proposé est d'abord vérifié par l'intermédiaire de simples scénarios de simulation dont les solutions, analytiques et numériques, sont déjà connues. La complexité des simulations est augmentée de façon graduelle. L'approche de modélisation est finalement appliquée au site Olkiluoto (Finlande) où un laboratoire de recherche souterrain est en construction afin d'évaluer la faisabilité du stockage géologique profond de déchets nucléaires à haute activité. Les techniques de modélisation géologique mises au point permettent de modéliser facilement la géométrie des fractures identifiées à travers la caractérisation géologique in situ. De plus, le modèle numérique s'avère adéquat pour la simulation de l'écoulement et du transport de solutés dans ce site complexe. Ce travail de recherche présente une contribution au développement des techniques de modélisation hydrogéologique des milieux fracturés
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
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