1,720,959 research outputs found
Estimación espacio-temporal de la recarga potencial en la Cuenca Lerma, Estado de México
No full textModelación hidrometeorológica de áreas con riesgos de inundación en la cuenca del río La Sierra, en los estados Chiapas y Tabasco, México.
No full textLas inundaciones son fenómenos naturales difíciles de prevenir y controlar por el hombre. En el sureste de México, de forma cíclica se ha visto afectada por inundaciones de origen hidrometeorológico, dejando como consecuencias graves daños en las poblaciones y en el ambiente, ocasionando un gran deterioro en la producción agrícola, pecuaria, forestal, daños en la infraestructura y pérdidas humanas. En el estado de Tabasco, en la cual se encuentra asentada la ciudad de Villahermosa y las zonas aledañas, ha sufrido de inundaciones a través del tiempo en 1918, 1926, 1927, 1932 1935, 1959, 1968, 1969, 1973, 1980, 1989, 1990, 1995, 1999, 2007, 2008 y 2009. El objetivo del estudio es realizar la modelación hidrometeorológica, para determinar zonas susceptibles de riesgo de inundaciones en la cuenca del río La Sierra en el estado de Chiapas y Tabasco. Los materiales que se utilizados son: la documentación antecedente de la zona, datos diarios de estaciones convencionales meteorológicas e hidrométricas, cartografía impresa y digital, fotografías satelitales, equipo de cómputo y software para la modelación. El desarrollo del trabajo, consistió de las fases: compilación descriptiva de la región hidrológica y cartográfica, reconocimiento de campo, elaboración de mapa base, delimitación y caracterización de la cuenca, análisis hidrometeorológico, modelación hidrológica con el modelo MIKE SHE, modelación hidráulica con el modelo MIKE 11, calibración y validación del modelo. Como resultados del estudio, se modeló un área de 4,424.66 km2, con su cauce principal que se desarrolla por 245 km, con una pendiente media del 40% y una elevación media de 300 metros; presenta cauces del cuarto orden, con una densidad de drenaje de 0.29 km/km2. La geología predominante es caliza sedimentaria, el clima es cálido húmedo, con una precipitación media anual de 1550 a 5200 mm al año, la temperatura anual que oscila de 11°C hasta los 26°C, la evaporación anual en la zona que va desde los 700 hasta los 2200 mm y una evapotranspiración anual que va desde 1000 a 1700 mm. El tipo de suelo predominante en la zona es Luvisol Crómico (Lc). La cobertura vegetal predominante en la zona es del tipo pastizal, con el 30.47% de la superficie total. Se definieron áreas de influencia para las estaciones meteorológicas, utilizando la oscilación térmica, temperatura media, precipitación, evaporación, topografía, subcuencas de acuerdo a la hidrografía y uso de suelo de la zona, mediante un polígono, se digitalizaron las áreas con características semejantes. Se realizó la sincronización de los registros históricos de 8 estaciones hidrométrica y 26 estaciones meteorológicas, con datos diarios. Se eligieron los eventos del 18 al 23 de octubre de 1989 y del 29 de noviembre al 3 de diciembre de 1990, para definir las zonas de desborde, principalmente en las zonas bajas, haciendo uso del modelo hidrológico MIKE SHE acoplado al modelo hidráulico MIKE 11, generando los hidrogramas simulados, los cuales fueron comparados con los hidrogramas medidos, evaluados mediante la prueba de ajuste del método de Nash (0.84 a 0.98), coeficiente de determinación (0.87 a 0.99), el coeficiente de variación de la raíz cuadrada del cuadrado medio del error (0.09 a 0.29). Se calibró y validó el modelo, determinando las zonas vulnerables a inundación, zonificando la superficie más afectadas por inundaciones que van desde los 20 cm hasta los 5 metros de profundidad de agua en la superficie. Como alternativas de solución para disminuir los riesgos de inundación, se propuso la construcción de una presa de almacenamiento en el cañón Itzantún, la conformación de los bordos en la margen y desazolve de la zona baja, disminuyendo las zonas de inundación en un 90%. HYDROMETEOROLOGICAL MODELING OF FLOOD RISK AREAS IN LA SIERRA BASIN, IN CHIAPAS AND TABASCO STATES, MEXICO. ABSTRACT: Floods are natural phenomena difficult to prevent and control by man. In southeastern Mexico, cyclically has been affected by floods hydrometeorological, leaving serious consequences on populations and damage to the environment, resulting in a large decline in agricultural production, livestock, forestry, infrastructure damage and casualties. In the state of Tabasco, in which the city is settled in Villahermosa and surrounding areas, has suffered over time floods in 1918, 1926, 1927, 1932, 1935, 1959, 1968, 1969, 1973, 1980, 1989 , 1990, 1995, 1999, 2007, 2008 and 2009. The aim of the study is to hydrometeorological modeling to determine risk areas susceptible to flooding in the basin of the river La Sierra in the state of Chiapas and Tabasco. The materials used are documenting history of the area, daily data of meteorological and hydrometric conventional stations, print and digital mapping, satellite photography, computer equipment and software for modeling. The development work consisted of phases descriptive compilation of the hydrologic region and mapping, field survey, preparation of base map delineation and characterization of the basin hydrometeorological analysis, hydrological modeling with MIKE SHE model, hydraulic modeling with MIKE 11 model, calibration and validation of the model. As results of the study, we modeled an area of 4424.66 km2, with its main channel that develops 245 km, with an average gradient of 40% and an average elevation of 300 meters, presents the fourth-order channels, with a drainage density km/km2 0.29. The predominant sedimentary limestone geology, the climate is hot and humid, with an average annual rainfall of 1550-5200 mm per year, the annual temperature ranging from 11 °C to 26 °C, the annual evaporation in the area from 700 to 2200 mm and an annual evapotranspiration ranges from 1000-1700 mm. The predominant soil type in the area is Chromic Luvisol (Lc). The predominant vegetation in the area is grassland type, with 30.47% of the total area. Catchment areas were defined for weather stations, using the temperature variation, average temperature, precipitation, evaporation, topography, watersheds according to hydrography and land use of the area by a polygon, digitized areas with similar characteristics. Synchronization was performed historical records hydrometric stations 8 and 26 weather stations with daily data. Events were chosen from 18 to 23 October 1989 and from 29 November to 3 December 1990, to define overflow areas, mainly in the lowlands, using MIKE SHE hydrological model coupled to the hydraulic model MIKE 11 generating simulated hydrographs, which were compared with measured hydrographs, evaluated by test method setting Nash (0.84 to 0.98), coefficient of determination (0.87 to 0.99), the coefficient of variation of the square root of the square error mean (0.09 to 0.29). Was calibrated and validated the model, identifying areas vulnerable to flooding, zoning the area most affected by floods ranging from 20 cm to 5 meters depth of water on the surface. As alternative solutions to reduce flood risks, proposed the construction of a storage dam in the canyon Itzantun, forming the margin levees and dredging of the lower, reducing flood areas by 90%.Tesis (Maestría en Ciencias, especialista en Hidrociencias).- Colegio de Postgraduados, 2013.Consejo Nacional de Ciencia y Tecnología (CONACYT)
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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