Távara Mendoza, Luis Arístides; Mantic, Vladislav; Graciani Díaz, Enrique; Blázquez Gámez, Antonio; París Carballo, Federico
2011-01-01
En el presente trabajo se estudia el inicio y crecimiento de una grieta de interfaz entre fibra y matriz bajo cargas transversales biaxiales de tracción - tracción y tracción - compresión. Se considera un problema simplificado en relación a una lámina unidireccional real, con una fibra inmersa en una matriz cuyas dimensiones externas son mucho más grandes que el radio de la fibra. El objetivo es predecir por un lado las cargas de fallo (cargas criticas) que originan el despegue en ...
Carga crítica en cimientos superficiales continuos
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Álvaro J. González García
1987-01-01
Full Text Available Se presenta un método para evaluar la carga crítica en cimientos superficiales continuos. Se denomina carga crítica (q crit de un cimiento la carga máxima que es posible aplicar a este sin exceder en ningún punto bajo el cimiento la resistencia del suelo de fundación. La carga última (q ult, por otro lado, es la carga máxima aplicable al cimiento antes de que se presente flujo plástico total del suelo. La relación entre carga última y carga critica sería el factor de seguridad mínimo utilizable para no inducir fallas puntuales, que pueden llevar a colapso total por medio de falla progresiva en el caso de suelos frágiles, metaestables, etc.
Gricelda Medina Veloz; Francisco Javier Luna Rosas; Jaime Muñoz Arteaga; Julio César Martínez Romo
2008-01-01
El enfoque del uso de patrones en el desarrollo de software se ha popularizado a nivel mundial y dentro de la ingeniería de software se ha extendido cada vez más su uso, a tal grado que se han creado y se siguen creando catálogos de patrones para solucionar problemas en el desarrollo de software a distintos niveles de abstracción. Este trabajo se centra en destacar el diseño mediante patrones de software de un servicio de balanceo de carga para aplicaciones distribuidas desarrolladas bajo el ...
Análisis comparativo de esquemas de balanceo de carga en ambientes de procesamiento distribuido
Scarpa, Diego; Baraldi, Waldemar A.; Vázquez, Gustavo Esteban; Ponzoni, Ignacio; Ardenghi, Jorge Raúl
2001-01-01
En este trabajo se presentan distintos enfoques para resolver el problema de balanceo de carga sobre ambientes de procesamiento distribuido. Las arquitecturas propuestas están organizadas bajo un filosofía Master-Worker y su implementación fue realizada en C++ utilizando la librería de pasaje de mensajes PVM. Las distintas políticas de balanceo de carga fueron comparadas para una amplia variedad de casos de estudio con el objetivo de estableces los alcances y limitaciones que cada alternativa...
Determinación del comportamiento bajo cargas concentradas de perfiles de lámina delgada ( MM
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Maritzabel Molina Herrera
2006-09-01
Full Text Available En el campo de la lámina delgada continuamente aparecen nuevos tipos de perfiles que son desarrollados con el objeto de mejorar los ya existentes. Un ejemplo de esto es la aparición del perfil M, elaborado para melorar la eficiencia a corte del perfil C y su resistencia al arrugamiento del alma por efecto de cargas concentradas. Teóricamente, se logra el objetivo de mejorar la resistencia a corte del perfil C y de algún modo su resistencia al arrugamiento del alma, pero debido a los dobleces generados en el alma (rigidizadores intermedios para acortar la longitud de pandeo, se producen comportamientos que desde el punto de vista de esfuerzos por flexión y deflexiones no pueden ser analizados con los fundamentos teóricos de la mecánica tradicional. Este comporta- miento se ve acentuado con la presencia de cargas concentradas. Por la razón expuesta anteriormente, a parte de la determinación de la resistencia teórica del perfil M (basada en el AISI 1996, se desarrollan pruebas sobre cuatro modelos de los que se obtienen tópicos como: carga máxima resistida, identificación visual del posible tipo de falla, deflexiones (centro de la luz y deformaciones unitarias (x, y, xy, y adicionalmente se elaboran modelos matemáticos simplificados y por elementos finitos (en el programa COSMOS/M, con el fin de hacer una revisión detallada del comportamiento de los esfuerzos y deformaciones en el perfil. La calibración de estos modelos se lleva a cabo con base en los resultados obtenidos de los ensayos. De otra parte, se hacen pruebas cíclicas balo cargas pseudoestáticas, con el objeto de estudiar el comportamiento histerético del perfil MM, con y sin rigidizadores.
Imagenología y distribución de cargas en la muñeca normal y postquirúrgica
Márquez Flórez, Kalenia María
2014-01-01
En este trabajo se determinó la distribución de cargas en la articulación radio-carpiana en la muñeca, bajo condiciones de carga y geometría, asociadas a tratamientos de artrodesis en estado estático. Para esto, se empleó el método discreto Rigid Body Spring Model (RBSM) en un modelo tridimensional de una muñeca sana. El método RBSM también se aplicó a modelos en los cuales se simularon condiciones de la muñeca luego de algún tratamiento de artrodesis, y los resultados obtenido...
Diseño de celda de carga optoelectrónica
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Francisco J. Martínez Serrano
2008-01-01
Full Text Available Los sistemas de medición representan una herramienta indispensable en todas las actividades productivas, y en el caso de empresas que aprovechan los avances del desarrollo tecnológico para mejorar la calidad de sus productos éstos son fundamentales. Frecuentemente en la industria de la manufactura metalmecánica se requiere controlar con gran precisión el ajuste de dos piezas ensambladas a presión, los materiales de ingeniería deben someterse constantemente a pruebas de resistencia, los equipos de pruebas de balanceo y vibraciones mecánicas funcionan bajo el principio de medición de fuerzas. Los métodos de medición más precisos utilizan dispositivos electromecánicos conocidos como celdas de carga, que consisten básicamente en una fina resistencia eléctrica adherida a un elemento mecánico sometido directamente o no, a las cargas de trabajo. Las cargas cíclicas que sufre el elemento mecánico afectan igualmente a la resistencia eléctrica, y debido a que está hecha de un alambre muy delgado, su capacidad a resistir elásticamente deformación es limitada. Con este proyecto se pretende construir una celda de carga opto-mecatrónica, cuyo principio de funcionamiento está basado en que gracias a la aplicación de carga en un elemento mecánico, se produce en éste cierta deformación. Esta deformación reduce la distancia entre el emisor y el receptor, provocando un cambio en la señal eléctrica. Cabe señalar que la distribución de intensidad luminosa varía entre el emisor y el receptor debido al desplazamiento generado (R. Jones, 1985; Martínez, 2004. A la celda de carga se le adaptó un emisor de infrarrojo cuya señal es recibida por el detector en el otro extremo. Se pretende demostrar que este sistema optoelectrónico es capaz de medir cargas externas sobre un elemento mecánico a través de un método indirecto para medir esfuerzos. Se ha implementado un prototipo sensible a deformación inducida a un elemento mec
Análisis del amortiguamiento en vidrio estructural bajo cargas de impacto
Ramos, Alberto; Pelayo, F.; Lamela, María Jesús; Fernández Canteli, Alfonso; Huerta Gómez de Merodio, María Consuelo; Pacios Alvarez, Antonia
2013-01-01
Los últimos avances tecnológicos y las tendencias arquitectónicas actuales han impulsado notablemente el uso de una gran variedad de productos de vidrio en la construcción que, en función de sus propias características, permiten diseñar y calcular elementos estructurales de este material bajo condiciones de seguridad. Este trabajo presenta la evaluación y el análisis de las propiedades de amortiguamiento de placas rectangulares de vidrio laminado de 1938 mm x 876 mm con distinto espesor, segú...
Modelización de Terrenos Granulares Sometidos a Gran Número de Ciclos de Carga
Illueca Jové, Manuel
2011-01-01
El presente trabajo describe el proceso llevado a cabo para la obtención de los asientos producidos por la cimentación de un equipo dinámico sobre un terreno granular. En primer lugar, comenzamos obteniendo los esfuerzos dinámicos transmitidos por el equipo y la cimentación al terreno. Posteriormente, modelizaremos el comportamiento del terreno bajo esta carga dinámica para obtener los asientos producidos. Principalmente este trabajo se centra en la obtención de la deformación que sufre un te...
Revelando el signo de las cargas eléctricas usando un detector de polaridad entretenido
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Francisco Vera
2018-01-01
Full Text Available En este trabajo discutiremos la construcción, uso y funcionamiento de un detector de polaridad electrostática que fue diseñado con el propósito de hacer interesante y entretenida una clase introductoria acerca de la existencia de cargas eléctricas y sus interacciones. El detector de polaridad usa un circuito simple y un diseño que puede imprimirse en una impresora 3D. Así el lector puede armar su propio detector luego de comprar y ensamblar de manera fácil algunos componentes electrónicos de bajo costo. El cuerpo del detector tiene la forma de un tiburón martillo cuyos ojos se encienden de acuerdo al signo de la carga del objeto que se quiere medir. Esta forma divertida de tiburón permite construir actividades entretenidas en donde los estudiantes puedan investigar las propiedades fundamentales de las interacciones entre objetos cargados eléctricamente.
Proposta para estimar curva carga-recalque e capacidade de carga em estacas de madeira
Segundinho, Pedro Gutemberg de Alcântara; Miná, Alexandre José Soares; Dias, Antonio Alves; Regazzi, Adair José; Carreira, Marcelo Rodrigo
2014-01-01
Este trabalho teve como objetivo propor um método para estimar a curva carga-recalque e a capacidade de carga de estacas de madeira a partir do ajuste de equações de regressão não lineares utilizando o método de Gauss Newton modificado. Para isso, foram utilizados dados experimentais obtidos para 12 estacas de madeira, curvas carga-recalque durante a cravação e capacidade de carga determinada no ensaio de carregamento dinâmico, utilizando modelo teórico. Nesta pesquisa, realizada de forma pio...
Análisis de tensiones en árboles de geometría compleja bajo cargas debido al efecto giroscópico.
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M. Sánchez Noa
2005-09-01
Full Text Available En el presente trabajo se exponen los resultados del análisis realizado en árboles de compleja geometríapertenecientes a un multiplicador planetario tipo 2KH-A destinado a emplearse en aerogeneradores deelectricidad. En el mismo, se presentan los modelos físico-matemáticos de dichos árboles para seranalizados mediante el método de los elementos finitos, considerando el estado de carga que surge alfuncionar el mecanismo y contemplando el efecto adicional de las cargas giroscópicas. Se muestran laszonas de conflicto de tensiones y se analizan propuestas de diseño que permitan, garantizando laresistencia y rigidez, realizar variaciones dimensionales y mejorar la compacidad de los elementos,disminuyendo a la vez el peso de los mismos.
Proposta para estimar curva carga-recalque e capacidade de carga em estacas de madeira
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Pedro Gutemberg de Alcântara Segundinho
Full Text Available Este trabalho teve como objetivo propor um método para estimar a curva carga-recalque e a capacidade de carga de estacas de madeira a partir do ajuste de equações de regressão não lineares utilizando o método de Gauss Newton modificado. Para isso, foram utilizados dados experimentais obtidos para 12 estacas de madeira, curvas carga-recalque durante a cravação e capacidade de carga determinada no ensaio de carregamento dinâmico, utilizando modelo teórico. Nesta pesquisa, realizada de forma pioneira no Brasil, fez-se a análise do comportamento de estacas de madeira imersas no solo durante a cravação delas. As médias do erro percentual absoluto médio foram 4,0% e 29,3%, obtidas a partir das equações não lineares ajustadas via método de Gauss Newton modificado e proposto por Van Der Veen respectivamente. Concluiu-se que as equações ajustadas via método de Gauss Newton modificado conduziram a uma maior exatidão nas estimativas, apresentando boa concordância com os dados experimentais obtidos nos ensaios de carregamento dinâmico, indicando sua utilização para estimar a curva carga-recalque e a capacidade de carga em estacas de madeira.
Carga inmediata en implantes dentales Immediate loading of dental implants
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C. Concejo Cútoli
2005-10-01
Full Text Available El protocolo de carga convencional en una o dos fases quirúrgicas ha sido evaluado durante los últimos 30 años bajo todas las condiciones clínicas posibles. En comparación, la carga inmediata es un protocolo relativamente nuevo que necesita de una estricta evaluación clínica. Realizamos una búsqueda bibliográfica sobre los ensayos clínicos publicados de carga inmediata en función de las diferentes opciones terapéuticas que se pueden plantear. Se hallaron resultados comparables para las dos estrategias de carga en mandíbulas edéntulas. Para el tratamiento con prótesis inmediata de maxilares totalmente edéntulos, restauraciones parciales e unitarias es todavía necesaria una selección adecuada de pacientes y un diseño conservador de la prótesis provisional. La necesidad de ensayos clínicos sencillos aleatorizados de doble ciego, con suficiente número de pacientes y adecuado seguimiento, que comparen una determinada situación clínica con un patrón oclusal de la prótesis provisional bien definido, son imprescindibles para acabar de confirmar la seguridad de la técnica.The protocol for conventional loading in one or two surgical stages has been evaluated over the last 30 years under all the possible clinical conditions. By comparison, immediate loading is a relatively new protocol that requires strict clinical evaluation. We conducted a search of the literature published concerning clinical trials on immediate loading according to the different therapeutic options that could be considered. Comparable results were found for both loading strategies in edentulous mandibles. For treatment involving an immediate prosthesis for totally edentulous mandibles, partial and single tooth restorations, patients have to be selected adequately and provisional prostheses have to be designed conservatively. In order to completely confirm the safety of the technique, double-blind, simple, randomized clinical trials have to be carried out with
PRUEBAS DE CARGA NO DESTRUCTIVAS EN PILOTES
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LUIS IBAÑEZ MORA
2008-01-01
Full Text Available En el presente trabajo se abordan las experiencias en la utilización de la modelación matemática y la realización de pruebas de carga no destructivas en cimentaciones sobre pilotes para evaluar su capacidad de carga. Para ello se exponen los resultados obtenidos en pruebas de carga de más de 200 Toneladas, y la distribución de cargas en una estructura portuaria, evaluando su capacidad resistente. Se establecen comparaciones entre los métodos teóricos de calculo de la capacidad de carga del pilote aislado y modelos matemáticos, así como los resultados de la pruebas de carga a escala real.
EVALUACIÓN DE LA CARGA FÍSICA POSTURAL Y LA CARGA MENTAL DE UN PARRILLERO-CHEF
Ariza-Zambrano, Andrea
2015-01-01
El presente trabajo de fin de Máster se realizó con el objetivo de evaluar los riesgos de la carga física postural y carga mental a los que se ve expuesto el cargo del Parrillero-chef de un restaurante de comidas rápidas, es un caso real del centro de trabajo Burguer Parrilla & Company en la ciudad de Bogotá, Colombia. Trabajo que se realizó con el interés personal de conocer el nivel de riesgo de carga postural y carga mental al que se encuentra expuesto, ya que el sector de la industria ...
Análisis de sistemas de distribución radiales bajo condiciones de polución armónica
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Ramón Alfonso Gallego Rendón
2005-11-01
Full Text Available Los sistemas de distribución presentan un alto contenido de armónicos debido a la presencia de cargas no lineales tales como equipos electrónicos y elementos ferromagnéticos en saturación. El análisis de este tipo de sistemas es el objetivo del flujo de carga armónico. En este artículo se muestra una metodología de flujo de carga armónico adaptado a los sistemas de distribución dadas las particularidades propias de estos sistemas como es la topología radial. Igualmente se muestra una implementación computacional desarrollada bajo el esquema de programación orientada a objetos usando el sistema operativo Windows. Se presentan ejemplos de prueba IEEE. / Distribution systems can present a high harmonic level due to existence of non linear loads such as electronic equipment. The analysis of these systems is the objective of harmonic load flow. This document shows a new methodology of harmonic load flow which considers the distribution systems characteristics. Likewise it shows an object oriented software developed in Windows. IEEE test systems are presented.
Montalvo Ramírez, Luis
1991-01-01
Se presenta la concepción, diseño y construcción de unidades terminales romotas simples, modulares y de bajo costo, apropiadas para las necesidades de los sistemas de supervisión y control de cargas eléctricas en estacione urbanas de distribución de los países en vías de desarrollo.
Fatiga de cimentaciones bajo cargas cíclicas: aplicación al caso de la eólica marina
Serret i Magaz, Jordi
2012-01-01
En primer lugar se pretende ilustrar como el concepto de fatiga puede servir para dar un tratamiento unificado a distintas metodologías existentes para el cálculo de los efectos de cargas cíclicas en geotecnia. Para ello se usan dos métodos de orígenes y aplicación distinta: el método NGI para cimentaciones superficiales y el método Leblanc para pilotes cargados lateralmente. En segundo lugar se trata de explorar los resultados que ambos métodos proporcionan cuando se aplica...
Peñarrocha Oltra, David
2014-01-01
Comparación de carga inmediata frente a carga convencional de implantes inmediatos con prótesis fijas de arco completo. OBJETIVOS El propósito del estudio fue evaluar las diferencias entre los protocolos de carga inmediata y carga convencional para rehabilitar a pacientes con el maxilar o la mandíbula parcialmente desdentados en los que esté indicada la extracción de todos los dientes remanentes, con prótesis fijas de arco completo sobre implantes dentales inmediatos y no inmediatos, e...
Diseño y operación de sistemas de distribución bajo un ambiente de redes inteligentes de tensión
Grisales Noreña, Luis Fernando
2015-01-01
En este trabajo se presenta una metodología para el diseño y operación de sistemas de distribución bajo un ambiente de redes inteligentes, considerando como elementos de análisis la ubicación y dimensionamiento de generación distribuida, elementos almacenadores de energía y elementos de protección para aislamiento de fallas y transferencia de carga (reconectadores normalmente cerrados y abiertos, respectivamente). Como técnicas de solución se emplearon tres algoritmos de optimización: algorit...
Análise de cargas acidentais em pavimentos de garagem
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D. A. Tenório
Full Text Available O trabalho tem como foco a análise das cargas acidentais utilizadas para pavimentos de garagem, considerando as recomendações de normas nacionais e internacionais para a definição do valor das cargas a serem aplicadas nas lajes nervuradas. A norma brasileira NBR 6120/1980 [1], que trata do assunto, não especifica nada em relação a cargas concentradas, enquanto normas internacionais como Euro Code [2] e IBC [3], recomendam considerar cargas distribuídas e concentradas. Atualmente, as lajes nervuradas são utilizadas amplamente em pavimentos de garagem. Neste contexto, considerando os padrões de veículos mais utilizados no país, será que os valores de cargas distribuídas das normas são adequados para o dimensionamento das lajes nervuradas? Ou é necessário fazer uma correção destas cargas para levar em consideração as cargas concentradas da ordem de 8,5 kN por pneu correspondente a um veículo utilitário. O objetivo deste trabalho é procurar as respostas para estas duas perguntas através de uma análise paramétrica envolvendo os principais parâmetros de uma laje nervurada, que são: a relação (lambda entre os lados, a distância entre as nervuras principais e o esquema de apoio da laje (uni ou bidirecional. De uma forma geral o conjunto das simulações mostra que as cargas recomendadas pelas normas citadas precisariam de correção quando utilizadas em pavimento de garagem para reproduzir o efeito das cargas concentradas das rodas de veículos tipo utilitário.
Cargas críticas de pandeo de columnas fisuradas
Moreno Fernández-Cañadas, Lorena María
2012-01-01
El presente trabajo tiene por objeto realizar un análisis de la carga crítica de pandeo de columnas sometidas a diversas condiciones de sustentación. A su vez, se estudiarán los efectos de la presencia de una fisura en la columna sobre dicha carga crítica en función de su tamaño y posición. Actualmente, el cálculo de dicha carga crítica por medio de programas comerciales que aplican el método de elementos finitos requiere un gran número de elementos por barra para conseguir ...
La Representación de las Cargas y el Análisis de los circuitos de Distribución
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Leonardo Casas Fernández
2011-03-01
Full Text Available Los nodos de las redes de alta tensión mantienen voltajes prácticamente balanceados desde donde se alimentan lascargas a través de transformadores con cambia taps bajo carga, los que conservan un voltaje por secundario sensiblementeconstante independientemente de la demanda. A los nodos de las redes de distribución, por el contrario, se conectan lostransformadores de distribución, los que se ven afectados por las variaciones de voltaje que ocurre en los circuitos, conlas correspondientes influencias sobre la demanda.Otra característica de las cargas en la distribución es la combinación o mezcla de consumidores domésticos,mayoritariamente monofásicas, y de clientes con instalaciones trifásicas formadas estas últimas casi exclusivamente pormotores asincrónicos, lo que ha hecho muy popular el uso de bancos de transformadores asimétricos, generadores decorrientes desbalanceadas.En este artículo se hace un estudio de la influencia que tiene la representación de las cargas sobre los resultados de losanálisis de los circuitos, fundamentalmente sobre las pérdidas. Voltages at high voltage buses are practically balanced and from them loads are connected through tap changeunder load transformers. So secondary voltages are perceptibly constant independent of the power demanded byloads. On the other hand, distribution transformers are connected at distribution buses, where voltage varies, and thepower demanded by loads also changes, as does the voltage.Another characteristic of distribution loads is the mixture of home applications, single phase loads; with three phaseones, basically induction motors, which need asymmetric transformer banks, associated to unbalanced currents.In this paper, an analysis on the influence of load representations about the results of circuit analysis is made, relatedto power and energy losses.
Tributación del Sector Transporte de Carga en Uruguay
Pedro Buonomo
2004-01-01
El objetivo general de este estudio es determinar la carga tributaria efectiva que incide sobre el transporte de cargas, en particular para los modos transporte terrestre (camión) y transporte aéreo, en la República Oriental del Uruguay.
Comportamiento de un puente histórico de arco de albañilería ante cargas dinámicas
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Yesid Mauricio Ospina
2009-09-01
Full Text Available En el presente artículo se describe el proceso de análisis al que fue sometido un puente histórico de arco de ladrillo construido en Colombia durante el siglo XVIII con el fin de predecir su comportamiento ante cargas producidas por sismos y determinar su vulnerabilidad. Dos estudios previos al análisis sísmico fueron realizados para obtener así información básica acerca del com- portamiento global de la estructura: un análisis estático lineal y un análisis modal, ambos a partir de un modelo tridimensional que se elaboró haciendo uso del método de elementos finitos. Se simuló la excitación sísmica bajo las condiciones propuestas en la norma sismorresistente del año 1998 (NSR-98. Los resultados obtenidos fueron coherentes con la historia del puente y sus respuestas frente a terremotos; la comparación entre las cargas sísmicas y la capacidad resistente de los materiales que constitu- yen la estructura confirma la vulnerabilidad de este tipo de edificios frente a daños localizados y posibilidades de colapso. Final- mente, los resultados sugieren la aplicabilidad del procedimiento desarrollado a otras estructuras históricas en Colombia.
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Edgar Giovanny Dias Segura
2013-01-01
Full Text Available La respuesta de diferentes pilotes sometidos a carga vertical axial fue estudiada empleando una serie de análisis mediante elementos finitos, considerando como suelo de fundación diez tipos de arenas en condición seca y saturada. A partir de los resultados obtenidos, se propone un método simplificado para estimar la carga última en pilotes preexcavados sobre arenas, en términos del diámetro y enterramiento del pilote, peso unitario del suelo, condiciones de saturación, y mediciones indirectas de la resistencia al corte del suelo, obtenidas a partir de la densidad relativa y el índice de penetración SPT. El método propuesto, basado en 180 casos analizados, ofrece una precisión de 92%, y constituye una herramienta complementaría de diseño para estimar la carga última de pilotes preexcavados en arenas.
Carga Imediata oclusal vs Carga Imediata no sector posterior
Veiga, Hélia
2014-01-01
Trabalho final do 5º ano com vista à atribuição do grau de mestre no âmbito do ciclo de estudos de Mestrado Integrado em Medicina Dentária apresentado à Faculdade de Medicina da Universidade de Coimbra. No âmbito da implantologia existem diversos estudos clínicos abordando carga imediata. Contudo, este tópico está ainda envolto em alguma controvérsia, ocorrendo, igualmente, interpretação subjectiva na utilização do papel de articulação na aferição de contactos em muitos desses estudos. At...
Cargas actuantes en túneles de Moa
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Roberto Blanco-Torrens
2000-03-01
Full Text Available Para la confección del presente trabajo se realizó un estudio que abarcó 2 km de túneles del municipio Moa a los que se les hizo un análisis detallado del macizo rocoso que los circunda, y se determinaron las propiedades físico-mecánica de las rocas, agrietamiento, afluencia de agua y sus consecuencias, etc. Se valoró la estabilidad por varias metodologías (Barton, Bieniawsky, Bulichev y otras y fueron usados, por sus resultados, los valores obtenidos del empleo de la de Barton. Se estableció el mecanismo de acción de la presión minera y se caracterizó en dos casos típicos, a partir de los cuales se determinan los valores de las cargas estáticas que se pueden producir. Se consideró el macizo como un cuerpo elástico, homogéneo e isotrópico para establecer el estado tensional inicial y así calcular las cargas dinámicas que pueden actuar. Además se puntualizan los valores de las cargas considerados como críticos.
Radiación de cargas aceleradas y el principio de equivalencia
Sudarsky, Daniel
2012-01-01
En este artículo revisaremos, desde el punto de vista cuántico, el problema conceptual que aparece al analizar la radiación electromagnética de cargas aceleradas desde el punto de vista de observadores ca-acelerados con las cargas.
Análisis de la carga de entrenamiento en fútbol
Gómez Dotor, Guillermo
2013-01-01
En las siguientes líneas se podrá encontrar un documento perteneciente al Trabajo Fin de Grado realizado por el alumno Guillermo Gómez Dotor. Dicho trabajo tendrá un tema central de estudio y análisis, la carga de entrenamiento aplicada en fútbol. En él, podremos encontrar dos partes diferenciadas. La primera de ellas, más teórica, consistirá en un análisis de la carga de entrenamiento a nivel general y sus aplicaciones al entrenamiento de fútbol. Se analizarán los conceptos de carga de...
Control de la carga de entrenamiento en el ciclismo
Cragnulini, Franco Emmanuel
2013-01-01
El objetivo de la presente revisión bibliográfica es describir cuales son los indicadores que permiten cuantificar la carga de entrenamiento en el ciclismo. La cuantificación de la carga de entrenamiento es de suma importancia si se pretende analizar y establecer relaciones de causa-efecto entre el trabajo realizado y las adaptaciones fisiológicas provocadas. Entre los más utilizados podemos resaltar al índice de esfuerzo percibido, la frecuencia cardiaca y la producción de potencia. Comprend...
Energy Technology Data Exchange (ETDEWEB)
Ortega S, Cesar A; Pacheco A, Maria Jojutla; Orozco V, Jaime A; Cristin V, Miguel A [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)
2004-07-01
The appropriate monitoring and control of the charging of lead-acid (LAB) batteries is an increasing necessity in an industry that demands systems with low maintenance costs and high availability. The problem of extending the batteries useful life becomes more complex when the batteries are charged through photovoltaic panels. The purpose of the present article is to offer the description of the system for monitoring and control for the charging of batteries developed at the Instituto de Investigaciones Electricas (IIE). This system performs a continuous monitoring of the charging state of the battery and of the main operation parameters. With the extracted information of the data, the fine tuning algorithm control can be made. The data are acquired in a personal computer through a serial connection. Once stored, they are presented to the user in a graphical way so that they can be analyzed. [Spanish] El adecuado monitoreo y control de carga de baterias plomo-acido (BPA) es una necesidad creciente en una industria que demanda sistemas con bajos costos de mantenimiento y alta disponibilidad. El problema de extender la vida util de las baterias se vuelve mas complejo cuando las baterias son cargadas a traves de paneles fotovoltaicos. La intencion del presente articulo es ofrecer la descripcion del sistema para monitoreo y control de carga de baterias desarrollado en el Instituto de Investigaciones Electricas (IIE). Este sistema realiza un monitoreo continuo del estado de carga de la bateria y de los principales parametros de operacion. Con la informacion extraida de los datos, se puede hacer la sintonizacion fina del algoritmo de control. Los datos se adquieren en una computadora personal a traves de un enlace serial. Una vez almacenados, se presentan al usuario de manera grafica para que puedan ser analizados.
DEFF Research Database (Denmark)
Li, Y.; Nielsen, Peter V.
2011-01-01
There has been a rapid growth of scientific literature on the application of computational fluid dynamics (CFD) in the research of ventilation and indoor air science. With a 1000–10,000 times increase in computer hardware capability in the past 20 years, CFD has become an integral part...... of scientific research and engineering development of complex air distribution and ventilation systems in buildings. This review discusses the major and specific challenges of CFD in terms of turbulence modelling, numerical approximation, and boundary conditions relevant to building ventilation. We emphasize...... the growing need for CFD verification and validation, suggest on-going needs for analytical and experimental methods to support the numerical solutions, and discuss the growing capacity of CFD in opening up new research areas. We suggest that CFD has not become a replacement for experiment and theoretical...
La carga global del cáncer (The Global Cancer Burden)
Centers for Disease Control (CDC) Podcasts
2012-02-02
Este podcast describe la carga global del cáncer y los esfuerzos de los CDC y otras entidades para reducir esa carga. Created: 2/2/2012 by National Center for Chronic Disease Prevention and Health Promotion (NCCDPHP). Date Released: 3/13/2012.
Directory of Open Access Journals (Sweden)
Ismael García García
2015-03-01
Full Text Available En los últimos años, el uso de vidrio laminado como elemento estructural se ha incrementado considerablemente en construcciones arquitectónicas, sobre todo en fachadas, cubiertas, escaleras o ventanas de seguridad. El cálculo de estos elementos tipo sándwich no es sencillo debido a la combinación de las propiedades mecánicas del vidrio (elástico-lineales con las del polímero interior (viscoelástico-lineales. Recientemente, algunos autores han propuesto el concepto de espesor efectivo para el cálculo simplificado de elementos de vidrio laminado bajo carga estática, utilizando un modelo monolítico con una rigidez equivalente igual a la del elemento laminado. Debido a la variación de propiedades del laminado con la temperatura, introducidas por el polímero viscoelástico, para cada cambio de temperatura se tiene un espesor efectivo diferente, lo que conlleva un mayor número de evaluaciones para cada una de las situaciones de trabajo del elemento laminado. En este trabajo se propone el concepto de módulo de elasticidad efectivo como una alternativa más eficiente para el cálculo con modelos de elementos finitos. La metodología propuesta se valida mediante ensayos experimentales realizados en placas de vidrio laminado sometidas a una carga uniformemente distribuida.
Factores que afectan la carga electrostática en polvos cerámicos
Directory of Open Access Journals (Sweden)
Fernández, J. F.
2011-04-01
Full Text Available The phenomenon of electrostatic charge in ceramic powders takes place when the particle surfaces enter in contact between them or with the containers. The accumulation of electrostatic charge is of relevance in ceramic powders in view of their insulating character and the risk of explosions during the material handling. In this work the main factors that affect the appearance of intrinsic charge and tribo-charge in ceramic powder have been studied. In ceramic powders of alumina it has been verified that the smallest particle sizes present an increase of the electrostatic charge of negative polarity. A correlation has been observed between the nature of the OH -surface groups and the electrostatic charge. The intrinsic charge and the tribocharge in ceramic powders can be diminished by compensating the surface groups that support the charge. The dry dispersion of nanoparticles on microparticles allows surface charge compensation with a noticeable modification of the powder agglomeration.
Los fenómenos de carga electroestática en polvos cerámicos se producen cuando las superficies de los mismos entran en contacto entre sí y con los elementos que las contienen. La acumulación de cargas electrostática es importante en polvos cerámicos dado su carácter aislante y debido al riesgo de explosiones por descarga. En este trabajo se estudian los principales factores que afectan a la aparición de carga neta y la tribocarga en las partículas de polvo cerámico. En polvos cerámicos de alúmina se ha comprobado que las partículas más finas presentan un aumento de la carga electrostática con una polaridad negativa. Se ha observado una correlación entre la naturaleza de los grupos OH- superficiales y la carga electrostática. La carga neta y la tribocarga en polvos cerámicos se pueden reducir si se compensan los sitios superficiales que soportan dicha carga. La dispersión en seco de nanopartículas sobre micropartículas permite la
Os efeitos da idade na seleção de carga perceptual
Directory of Open Access Journals (Sweden)
Vanessa Coelho de Sousa
Full Text Available Algumas pesquisas sugerem a existência de momentos distintos de maturação do sistema atentivo. O presente estudo investigou os padrões de seleção da informação visual através de uma tarefa de carga perceptual executada por três grupos etários: crianças, adultos e idosos. De maneira geral os resultados obtidos indicaram uma diminuição da eficiência no processo de seleção da informação em condições de baixa carga perceptual na população de idosos e uma diminuição da eficiência da seleção em condições de alta e baixa carga perceptual na população composta por crianças. Estes resultados sugerem a existência de padrões específicos na seleção da informação visual em função da idade e da carga perceptual a ser processada pelo sistema visual.
Lifescience Database Archive (English)
Full Text Available CF (Link to library) CFD492 (Link to dictyBase) - - - Contig-U10808-1 CFD492P (Link to Original site) CFD492...F 583 CFD492Z 527 CFD492P 1110 - - Show CFD492 Library CF (Link to library) Clone ID CFD492...e URL http://dictycdb.biol.tsukuba.ac.jp/CSM/CF/CFD4-D/CFD492Q.Seq.d/ Representative seq. ID CFD492...P (Link to Original site) Representative DNA sequence >CFD492 (CFD492Q) /CSM/CF/CFD4-D/CFD492...omology vs CSM-cDNA Score E Sequences producing significant alignments: (bits) Value CFD492 (CFD492
Fco. Javier Luna Rosas; Rene Tristán Ávila; J. de Jesús Martínez Pedroza
2003-01-01
Balancear Carga significa como distribuir procesos entre procesadores conectados por una red, para equilibrar la carga de trabajo entre ellos. Los algoritmos de planeación distribuida global pueden ser divididos en dos grandes grupos: algoritmos de balanceo de carga dinámica y algoritmos de balanceo de carga estática. Los algoritmos de balanceo de carga estática, también referenciados como planeación de tareas obtienen la localización de todos sus requerimientos antes de comenzar su ...
Eleventh annual conference of the CFD Society of Canada (CFD 2003). Proceedings
International Nuclear Information System (INIS)
Ollivier-Gooch, C.
2003-01-01
The Eleventh Annual Conference of the CFD Society of Canada, CFD 2003, was held in Vancouver, British Columbia from May 28-30, 2003. The conference was attended by 125 delegates from twelve countries. In addition to traditional CFD applications in vehicle aerodynamics and turbulent flow, the conference also showcased a number of less traditional application areas, including fuel cells, biofluids, multi-phase flows, and flows in porous media
ESTIMACIÓN DE LA CARGA DE TRANSFORMADORES DE POTENCIA UTILIZANDO UNA RED NEURONAL ARTIFICIAL
Agudelo, Laura; Velilla, Esteban; López, Jesús M
2014-01-01
En este artículo se presenta una metodología para estimar la curva de carga de transformadores de potencia utilizando redes neuronales artificiales. Para implementar la metodología propuesta se utilizaron datos reales de dos transformadores ubicados en diferentes zonas geográficas y con diferentes condiciones de operación. La técnica de estimación de carga fue implementada con datos históricos de la empresa Interconexión Eléctrica S.A (ISA). Para realizar la predicción de las curvas de carga ...
Directory of Open Access Journals (Sweden)
Damià Vericat
2006-12-01
Full Text Available Este trabajo analiza el transporte de fondo (tasas y granulometría en relación con las variaciones temporales en la granulometría del lecho del río Ebro, en su tramo bajo y durante el periodo hidrológico 2002-2004. La alta magnitud de las crecidas (Q8 sucedidas en el 2002-2003 provocó una elevada actividad sedimentaria, especialmente en relación con la rotura de la coraza superficial del lecho. Dicho processo produjo un incremento progresivo en las tasas de transporte a causa de la incorporación del material subsuperficial a la carga de fondo. El flujo conjunto de materiales superficiales y subsuperficiales se considera como la causa principal que explica la elevada dispersión granulométrica de la carga de fondo durante las crecidas. Los caudales alcanzados durante las crecidas de 2003-2004 fueron de menor magnitud y con menor competencia para movilizar todas las fracciones granulométricas de la superfície del lecho. El movimiento de las partículas de mayor tamaño fue hidráulicamente limitado, lo que generó un transporte de fondo selectivo. Dicha dinánica fue la responsable del desarrollo de una nueva coraza superficial que redujo la disponibilidad de sedimentos y, consecuentemente, las tasas de transporte de fondo.
Directory of Open Access Journals (Sweden)
Pablo Emilio Rozo García
2013-09-01
Full Text Available En este documento se describe el proyecto correspondiente a el diseño e implementación de un banco de carga de tipo resistivo para pruebas de carga en Sistemas de alimentación ininterrumpidas monofásicas de capacidades comprendidas entre 1 KVA y 2 KVA. La estructura del proyecto presenta inicialmente la descripción teórica sobre los conceptos fundamentales en electrónica de potencia y en referencia con los bancos de carga que se encuentran actualmente en el mercado. Posteriormente se realiza el diseño del banco de carga resistivo con base en la investigación ya existente y finalmente se implementa el diseño, resaltando los resultados obtenidos, conclusiones, dificultades técnicas y mejoras al proyecto. A partir de los resultados obtenidos, se entrega una herramienta de trabajo para la industria de sistemas de potencia en general y material de investigación en áreas relacionadas con el análisis de la calidad de energía y electrónica de potencia.
Directory of Open Access Journals (Sweden)
Francisco Javier Moreno
2015-01-01
Full Text Available Previous studies have pointed out the convenience of taking the characteristics of the skill to be learned and the intrinsic characteristics of the learners into account when designing practice tasks. Nevertheless, few studies have manipulated the amount of variable practice. The ability to adapt, as an inherent feature of biological systems, can be an adequate framework to explain and predict motor learning processes. This paper is based on adaption processes explained under the theory of allostasis and the general adaption syndrome and shares the background of the Dynamic Systems Theory, to propose the concept of practice load as a useful tool to quantify variability of practice in motor learning. From this standpoint, the conditions of variable practice are reviewed to be a stimulus in an adequate magnitude and direction to take the learner to a higher level of performance and hence to optimize motor learning. Resumen Muchos autores han recomendado la conveniencia de ajustar los niveles de práctica variable teniendo en cuenta las características de la tarea y la variabilidad intrínseca que muestra el aprendiz en la ejecución de la habilidad. Sin embargo, no son numerosos los trabajos que han manipulado varios niveles de cantidad de variabilidad al practicar. La capacidad de adaptación, como rasgo de los sistemas biológicos puede resultar un marco adecuado para afrontar esta cuestión. En este trabajo, apoyado en los procesos de adaptación explicados bajo las teorías de alostasis y el síndrome general de adaptación (GAS, y bajo presupuestos compartidos por la Teoría General de Sistemas Dinámicos, propondrá el concepto de carga de práctica como una herramienta para cuantificar la práctica en el aprendizaje motor. Bajo esta perspectiva se revisan las condiciones en las que la práctica en variabilidad debe modularse, para suponer una estimulación que facilite al aprendiz una adaptación a un nivel de rendimiento superior y con
Tenth annual conference of the CFD Society of Canada (CFD 2002). Proceedings
International Nuclear Information System (INIS)
Barron, R.M.
2002-01-01
The Tenth Annual Conference of the CFD Society of Canada, CFD 2002, was held in Windsor, Ontario from June 9-11, 2002. Contributions and participation were from many countries including Canada, United States, United Kingdom, France, Belgium, Germany, Iran, India, Pakistan, China, Japan, Singapore, Kuwait and Russia. The proceedings are a collection of the papers received covering the spectrum of computational fluid dynamics (CFD) from fundamental advances to improved algorithms to traditional and innovative applications. There is also a special session on automotive applications
CFD Simulations of Soap Separation; CFD-simulering av avsaapning
Energy Technology Data Exchange (ETDEWEB)
Birkestad, Per
2010-07-01
A part of Vaermeforsk, the 'Skogsindustriella programmet', has identified the possibility to increase the production of tall oil, and hence the competitiveness, in Swedish pulp mills through an increase in the efficiency of the soap separation tanks. Currently, soap is extracted from the black liquor through a sedimentation process where the less dense soap rise to the top of the liquor tank where it is removed through a over-flow ducting at the top of the tank. Vaermeforsk seeks a better understanding of the detailed flow and the separation mechanisms within the liquor tanks and has initiated a study of computational fluid dynamics (CFD) of the tanks. The aim of the study has been threefold; To develop CFD-methods for use in the study of soap separation processes, to investigate the detailed flow within two Swedish liquor tanks and one North American soap skimmer and lastly to develop new design rules for use in future designs of soap separation tanks. The project shows that CFD is a useful tool for the investigation of black liquor and soap flow within a soap separation tank. The CFD simulations of three existing liquor tanks show that the previously used design-rules based on surface loads are inadequate as the actual flow velocities within the tanks are two orders of magnitude larger than those previously used as reference (the surface load). The CFD simulations also show that the black liquor flow, and hence the soap separation, is very sensitive to density variations on the black liquor inlet and temperature variations as small as 1 deg C can significantly affect the liquor flow.
Función del diafragma durante la colocación de cargas sobre el abdomen en sujetos normales
Directory of Open Access Journals (Sweden)
Sergio G. Monteiro
2012-04-01
Full Text Available Los efectos de las cargas en el abdomen con el objeto de producir entrenamiento del diafragma, no han sido suficientemente evaluados. Estudiamos la función del diafragma durante la colocación de cargas sobre el abdomen y con cambios en el patrón respiratorio. Se estudiaron 6 voluntarios normales. Se obtuvo flujo en la boca, presión gástrica (Pga, presión esofágica (Pes, movimiento torácico (TX y abdominal (AB, presión inspiratoria máxima (PImax y presión transdiafragmática media (Pdi y máxima (Pdimax. Se calculó la relación Pdi/Pdimax y el índice tensión-tiempo del diafragma (TTdi. Etapas: patrón normal (PN, patrón abdominal (PA y carga de 1, 2, 4 y 6 kg con PN y PA. El PA fue facilitado por las cargas sobre el abdomen. Solo con 6 kg (PN y PA la Pga a capacidad residual funcional aumentó significativamente (p 0.001. La Pdi siguió a las variaciones de la Pga y aumentó con todos los PA (p < 0.001. Con PA y carga el índice TTdi alcanzó un valor de 0.05 ± 0.02 (p < 0.001. Las cargas no aumentaron este índice más de lo que hizo el PA solo. Nuestros hallazgos sugieren que las cargas sobre el abdomen aumentan la propiocepción relacionada con los movimientos respiratorios y descenso del diafragma. Las cargas producen cambios leves en la mecánica del diafragma (en sujetos normales, 1/3 de la carga necesaria para desarrollar fatiga. En sujetos normales estos cambios parecen ser insuficientes para producir entrenamiento de los músculos respiratorios.
Uso público y capacidad de carga perceptual en espacios naturales protegidos
Directory of Open Access Journals (Sweden)
Felipe Leco Berrocal
2013-01-01
Full Text Available Este trabajo muestra algunos de los resultados de la investigación realizada en el Proyecto «Las áreas de uso público en la Reserva de la Biosfera de Monfragüe. Accesibilidad y capacidad de carga» (Plan Nacional de Investigación Científica, Desarrollo e Innovación Tecnológica 2004-2007. Orden MAM/321/207. Expte. 024/SGTB/2007/4.1. En líneas generales, se presenta un estudio de las principales áreas de uso público desde la perspectiva de la capacidad de carga, ya que dichas áreas polarizan por regla general los flujos de usuarios, las inversiones y son el eje principal sobre el que descansa la afluencia de usuarios al Parque, por ello es necesario evaluar no sólo la capacidad de carga sino también la intensidad de su uso.
Directory of Open Access Journals (Sweden)
G. Rivero Llerena
2003-01-01
Full Text Available El uso de los reductores de velocidad comenzó a principios del siglo xx, su extensa difusión en el mundo actual permiteadquirirlos como unidades ensambladas a un costo relativamente bajo para la calidad del producto ofertado. Losantecedentes de este trabajo están en las investigaciones realizadas desde hace más de tres décadas en el ISPJAE. Lacreación de tecnologías propias sobre la base de estas investigaciones ha permitido la producción de reductores develocidad por tornillo sinfín con índices de calidad comparables con los índices de los reductores foráneos. El método dereconversión de reductores de velocidad que han quedado fuera de servicio, es utilizado en Cuba con resultadossatisfactorios a partir de la utilización de las carcasas originales. El presente trabajo pretende destacar la influencia de loserrores de contacto en la capacidad de carga de la transmisión por tornillo sinfín. Se brinda en esta ocasión, unprocedimiento para el cálculo automatizado de la superficie activa del diente de la rueda y se ofrece una expresión decálculo propia que permite pronosticar la capacidad de carga de la transmisión, a partir de la huella de contacto, encorrespondencia con los requisitos de contacto para un grado de precisión dado.Palabras claves: Capacidad de carga, huella de contacto, tornillo sinfín._____________________________________________________________________________Abstract.The use of worm gears transmissions started at the beginning of the 20th century and its wide spread use allow to purchaseas join units with low cost according to the product quality. Investigations that for more than thirty years took place at theISPJAE are the bases of this study. The Cuban technologies have permitted to produce worm gears with a comparablequality as foreign ones. The reconversion method for worm gears out of service is used in Cuba, and satisfactory results areobtained. In this paper are exposed the contact errors influence
Alcance y limitaciones de la carga dinámica de la prueba en el proceso judicial
Montilla Rosero, Carmen Alicia; Jiménez Pascuaza, Johana Marcela
2016-01-01
La carga dinámica de la prueba hace parte del derecho probatorio que le brinda más beneficios a la parte procesal que se encuentre en mejores condiciones de hacerlo. Este tipo de carga procesal fue usada por el Consejo de Estado para resolver episodios de responsabilidad administrativa por la actividad médica entre los años 1990 a 2006, debido a las dificultades con las que contaba el paciente para probar hechos constitutivos de la falla del servicio médico estatal. Al inicio, la carga probat...
CFD for Nuclear Reactor Safety Applications (CFD4NRS-4) - Workshop Proceedings
International Nuclear Information System (INIS)
2014-01-01
Following the CFD4NRS workshops held in Garching, Germany (Sept. 2006), Grenoble, France (Sep. 2008) and Washington D.C., USA (Sept. 2010), this Workshop is intended to extend the forum created for numerical analysts and experimentalists to exchange information in the application of CFD and CMFD to NRS issues and in guiding nuclear reactor design thinking. The workshop includes single-phase and multi-phase CFD applications, and offers the opportunity to present new experimental data for CFD validation. More emphasis has been given to the experiments, especially on two-phase flow, for advanced CMFD modelling for which sophisticated measurement techniques are required. Understanding of the physics has been depen before starting numerical analysis. Single-phase and multi-phase CFD simulations with a focus on validation were performed in areas such as: single-phase heat transfer, boiling flows, free-surface flows, direct contact condensation and turbulent mixing. These relate to NRS-relevant issues, such as pressurised thermal shock, critical heat flux, pool heat exchangers, boron dilution, hydrogen distribution in containments, thermal striping, etc. The use of systematic error quantification and the application of BPGs were strongly encouraged. Experiments providing data suitable for CFD or CMFD validation were also presented. These included local measurements using multi-sensor probes, laser-based techniques (LDV, PIV or LIF), hot-film/wire anemometry, imaging, or other advanced measuring techniques. There were over 150 registered participants at the CFD4NRS-4 workshop. The programme consisted of 48 technical papers. Of these, 44 were presented orally and 4 as posters. An additional 8 posters related to the OECD/NEA-KAERI sponsored CFD benchmark exercise on turbulent mixing in a rod bundle with spacers (MATiS-H) were presented and a special session was allocated for 6 video presentations. In addition, five keynote lectures were given by distinguished experts. The
Directory of Open Access Journals (Sweden)
Floriu00E1n Rosa Martu00EDnez Perdomo
2009-01-01
Full Text Available El artículo presenta un análisis del sistema de transporte de carga en la Ciudad de México desde el punto de vista sistémico, considerando las variables económicas, políticas, técnicas, sociales que permitan comprender la problemática que actualmente enfrenta esta ciudad en la movilidad de mercancías. Es una reflexión de carácter multidisciplinario basada en el método cualitativo para explicar y comprender la situación actual del transporte de carga en México dentro del contexto de la globalización económica, para identificar así la naturaleza profunda de la estructura dinámica del transporte de carga en la Ciudad y la nueva forma de conceptualizar al transporte de mercancías. Se estudia el comportamiento de los flujos e infraestructura de las redes viales, las características urbanas, los instrumentos jurídicos en las políticas del transporte, la problemática del transporte de carga, así como la movilidad y los diferentes problemas que enfrenta el sector en relación con la ciudad. El objetivo principal de presente artículo es enunciar las razones por las que no existe un sistema de transporte articulado y se privilegia el uso del autotransporte de carga. Finalmente, de acuerdo a las diversas variables analizadas, se establece en las conclusiones que el análisis y la planificación de los transportes debe ser multi e interdisciplinario por naturaleza, con una visión integral para establecer un equilibrio entre los modos de transporte.
Estructuras de elevadores de carga. // Dumbwaiter structure stress analysis.
Directory of Open Access Journals (Sweden)
G. Escobar Travieso
2006-09-01
Full Text Available Este trabajo tiene como objetivo analizar las tensiones y deformaciones que ocurren en las estructuras del marco de carro,plataforma y cabina de elevadores de carga mediante la aplicación del Método de los Elementos Finitos, específicamentedel montaplatos de 300 Kg. de capacidad, con vista a realizar el análisis de resistencia, racionalización del peso y material ylas posibles vías de solución.Palabras claves: Elevador de carga, estructuras, análisis de tensiones, elementos finitos.________________________________________________________________________________AbstractThis paper deals with the tension and deformation analysis in structures of lifter mark, platform and cabin offreight lifters by means of the Finite Elements Method, specifically the 300 kgs capacity dumbwaiter, in orderto carry out the resistance analysis, weight and material rationalization.Key words: Dumbwaiter, structures, stress analysis, finite elements.
Estructuras de elevadores de carga. // Dumbwaiter structure stress analysis.
Directory of Open Access Journals (Sweden)
G. Escobar Travieso
2004-05-01
Full Text Available Este trabajo tiene como objetivo analizar las tensiones y deformaciones que ocurren en las estructuras del marco de carro,plataforma y cabina de elevadores de carga mediante la aplicación del Método de los Elementos Finitos, específicamentedel montaplatos de 300 Kg. de capacidad, con vista a realizar el análisis de resistencia, racionalización del peso y material ylas posibles vías de solución.Palabras claves: Elevador de carga, estructuras, análisis de tensiones, elementos finitos._______________________________________________________________________________AbstractThis paper deals with the tension and deformation analysis in structures of lifter mark, platform and cabin offreight lifters by means of the Finite Elements Method, specifically the 300 kgs capacity dumbwaiter, in orderto carry out the resistance analysis, weight and material rationalization.Key words: Dumbwaiter, structures, stress analysis, finite elements.
Reforma de edificios antiguos. El rasgado de huecos en muros de carga
Soto Pardo, M.
1985-01-01
La apertura de huecos en muros de carga es una operación frecuente en la reforma de edificios antiguos. Una correcta ejecución exige la puesta en carga de la estructura sustentante —normalmente un pórtico metálico— mediante gatos hidráulicos o algo similar, cosa que suele omitirse, dando lugar a dos problemas diferentes: uno, el desprendimiento diferido del área de descarga, con alarmantes fisuraciones y otro, sin efectos ostensibles, pero mucho más peligroso, como es la sobrecarga elevadísim...
Benson, Thomas J.
1988-01-01
Supersonic external compression inlets are introduced, and the computational fluid dynamics (CFD) codes and tests needed to study flow associated with these inlets are outlined. Normal shock wave turbulent boundary layer interaction is discussed. Boundary layer control is considered. Glancing sidewall shock interaction is treated. The CFD validation of hypersonic inlet configurations is explained. Scramjet inlet modules are shown.
Análisis de grupos de pilotes sometidos a cargas de sismo
Directory of Open Access Journals (Sweden)
Carlos Javier Sainea Vargas
2011-07-01
Full Text Available Se presentan los análisis de los resultados obtenidos al emplear la metodología p-y en el análisis de un amplio número de modelos de grupos de pilotes, en los que se aplicaron modificaciones a las curvas p-y para la inclusión de los efectos de grupo y carga sísmica; dichos modelos han sido elaborados incluyendo diferentes configuraciones geométricas de los grupos, y varios tipos de suelos de cimentación. Para el análisis de los modelos se ha empleado el software especializado FB-Multipier, que, además de incluir la metodología elegida, permite la aplicación de cargas sísmicas reales, como las dadas por señales acelerográficas. A partir de los resultados de deflexiones y momentos obtenidos en el análisis de losmodelos, se presentan algunas observaciones sobre el comportamiento de los grupos de pilotes sometidos a carga sísmica y se incluyen consideraciones referentes a su diseño.
Carga diferida en implantología Delayed loading in implantology
Directory of Open Access Journals (Sweden)
J.C. de Vicente Rodríguez
2005-10-01
Full Text Available La implantología dental se ha convertido en una práctica con bases científicas con el descubrimiento de la biología de la oseointegración. El protocolo terapéutico clásico implicaba mantener los implantes libres de carga hasta que estuviesen oseointegrados. Sin embargo, las desventajas de este procedimiento condujeron posteriormente al desarrollo de un nuevo protocolo, en el que los implantes son cargados de forma inmediata tras su colocación. Sin embargo, este nuevo abordaje suscita dudas acerca de su destino último que aún no han sido resueltas. El objetivo del presente artículo es (i revisar y analizar críticamente las bases biológicas de la carga de los implantes y (ii proponer guías orientativas para elegir el momento ideal de carga de los mismos, en función de variables clínicas. Como conclusión, se establece que si bien las cargas inmediata y diferida proporcionan los mismos resultados en diversas situaciones, la segunda es preferible en presencia de determinados factores de riesgo para el éxito de la primera.Implant dentistry has become a scientifically based practice with the discovery of the biological basis of osseointegration. In the classical protocol, implants were load-free while bone was healing around them to ensure predictable osseointegration. However, several disadvantages of this approach have lead recently to a new protocol based on loading implants immediately after their placement. But, several questions about the outcome of this approach remain unanswered. Therefore, the aim of the present review article is to (i review and analyze critically the biological basis of the load of implants, and (ii propose guidelines for choosing the ideal moment to load dental implants, based on clinical variables. As a conclusion, delayed loading of implants remains the best protocol in several clinical situations.
Carga de trabajo en tres grupos de pacientes de UCI Española según el Nursing Activities Score
Directory of Open Access Journals (Sweden)
Francisco Javier Carmona-Monge
Full Text Available Se objetivó valorizar la carga de trabajo al ingreso y al alta en tres grupos de pacientes (síndrome coronario agudo, insuficiencia respiratoria aguda y sepsis en terapia intensiva. Estudio descriptivo, prospectivo, de 27 meses, incluyéndose 563 pacientes, valorando carga de trabajo según Nursing Activities Score. Existieron diferencias significativas en la carga de trabajo al ingreso y en el alta entre los grupos de pacientes, siendo superior en ambos momentos la de pacientes con insuficiencia respiratoria aguda y sepsis frente a pacientes coronarios. Durante los siete primeros días de estancia se mantuvo esta diferencia, desapareciendo a partir del octavo día, equilibrándose la carga de trabajo para los tres grupos. Para conseguir una adecuada dotación de personal es fundamental contar con instrumentos para medir las necesidades de cuidados y conocer la carga de trabajo de los distintos grupos de enfermos que ingresan con mayor frecuencia en las unidades de terapia intensiva.
Carga de trabajo en tres grupos de pacientes de UCI Española según el Nursing Activities Score
Directory of Open Access Journals (Sweden)
Francisco Javier Carmona-Monge
2013-04-01
Full Text Available Se objetivó valorizar la carga de trabajo al ingreso y al alta en tres grupos de pacientes (síndrome coronario agudo, insuficiencia respiratoria aguda y sepsis en terapia intensiva. Estudio descriptivo, prospectivo, de 27 meses, incluyéndose 563 pacientes, valorando carga de trabajo según Nursing Activities Score. Existieron diferencias significativas en la carga de trabajo al ingreso y en el alta entre los grupos de pacientes, siendo superior en ambos momentos la de pacientes con insuficiencia respiratoria aguda y sepsis frente a pacientes coronarios. Durante los siete primeros días de estancia se mantuvo esta diferencia, desapareciendo a partir del octavo día, equilibrándose la carga de trabajo para los tres grupos. Para conseguir una adecuada dotación de personal es fundamental contar con instrumentos para medir las necesidades de cuidados y conocer la carga de trabajo de los distintos grupos de enfermos que ingresan con mayor frecuencia en las unidades de terapia intensiva.
International Nuclear Information System (INIS)
2012-01-01
The purpose of the workshop was to provide a forum for numerical analysts and experimentalists to exchange information in the field of NRS-related activities relevant to CFD validation, with the objective of providing input to WGAMA CFD experts to create a practical, state-of-the-art, web-based assessment matrix on the use of CFD for NRS applications. The workshop included single-phase and multiphase CFD applications as well as new experimental techniques, including the following: Single-phase and two-phase CFD simulations with an emphasis on validation were sought in areas such as boiling flows, free-surface flows, direct contact condensation, and turbulent mixing. These should relate to NRS-relevant issues such as pressurized thermal shock, critical heat flux, pool heat exchangers, boron dilution, hydrogen distribution, and thermal striping. The use of systematic error quantification and Best Practice Guidelines (BPGs) was encouraged. Experiments providing data suitable for CFD validation-specifically in the area of NRS-including local measurement devices such as multi-sensor optical or electrical probes, Laser Doppler Velocimetry (LDV), hot-film/wire anemometry, Particle Image Velocimetry (PIV), Laser-Induced Fluorescence (LIF), and other innovative techniques. There were over 200 registered participants at the CFD4NRS-3 workshop. The program consisted of about 75 technical papers. Of these, 57 were oral presentations and 19 were posters. An additional 20 posters related to the OECD/NEA-sponsored CFD benchmark exercise on thermal fatigue in a T-Junction were presented. In addition, five keynote lectures were given by distinguished experts. This is about a 30 pc increase with respect to the previous XCFD4NRS workshop held in Grenoble in 2008, and a 70 pc increase compared to the first CFD4NRS workshop held in Garching in 2006. This confirms that there is a real and growing need for such workshops. The papers presented in the conference tackled different topics
Cuantificación y control de la carga de entrenamiento y competición en fútbol
Recuenco Serrano, David
2016-01-01
El estudio de la carga interna y la carga externa en el fútbol ha suscitado un gran interés en los últimos años. Desde la perspectiva de la carga interna, es necesario estudiar y conocer variables que nos permitan su análisis de forma rápida y poco invasiva. Esto puede conseguirse mediante el uso de métodos subjetivos como los test psicométricos o la escala de esfuerzo percibido RPE y métodos novedosos aplicados al deporte, como el registro de la variabilidad de la frecuencia cardíaca (VFC). ...
Twelfth annual conference of the CFD Society of Canada (CFD 2004). Proceedings
International Nuclear Information System (INIS)
Khalid, M.; Chen, S.; McIlwain, S.
2004-01-01
The Twelfth Annual Conference of the CFD Society of Canada, CFD 2004, was held in Ottawa, Ontario from May 9-11, 2004. The proceedings consists of 24 sessions covering the following topics: fluid structure interactions; multiphase and multi-species flows; mesh methods; turbulence; DNS/LES; supersonic and hypersonic flows; heat transfer; combustion and detonation; flow physics; aerodynamics; applications; algorithms; environmental flows; magnetohydrodynamics and electrohydrodynamics; biofluids; and, combustion and smoke management
Análisis de grupos de pilotes sometidos a cargas de sismo
Directory of Open Access Journals (Sweden)
Carlos Javier Sainea Vargas
2012-05-01
Full Text Available Se presentan los análisis de los resultados obtenidos al emplear la metodología p-y en el análisis de un amplio número de modelos de grupos de pilotes, en los que se aplicaron modificaciones a las curvas p-y para la inclusión de los efectos de grupo y carga sísmica; dichos modelos han sido elaborados incluyendo diferentes configuraciones geométricas de los grupos, y varios tipos de suelos de cimentación. Para el análisis de los modelos se ha empleado el software especializado FB-Multipier, que, además de incluir la metodología elegida, permite la aplicación de cargas sísmicas reales, como las dadas por señales acelerográficas. A partir de los resultados de deflexiones y momentos obtenidos en el análisis de losmodelos, se presentan algunas observaciones sobre el comportamiento de los grupos de pilotes sometidos a carga sísmica y se incluyen consideraciones referentes a su diseño.
Modeling Subgrid Scale Droplet Deposition in Multiphase-CFD
Agostinelli, Giulia; Baglietto, Emilio
2017-11-01
The development of first-principle-based constitutive equations for the Eulerian-Eulerian CFD modeling of annular flow is a major priority to extend the applicability of multiphase CFD (M-CFD) across all two-phase flow regimes. Two key mechanisms need to be incorporated in the M-CFD framework, the entrainment of droplets from the liquid film, and their deposition. Here we focus first on the aspect of deposition leveraging a separate effects approach. Current two-field methods in M-CFD do not include appropriate local closures to describe the deposition of droplets in annular flow conditions. As many integral correlations for deposition have been proposed for lumped parameters methods applications, few attempts exist in literature to extend their applicability to CFD simulations. The integral nature of the approach limits its applicability to fully developed flow conditions, without geometrical or flow variations, therefore negating the scope of CFD application. A new approach is proposed here that leverages local quantities to predict the subgrid-scale deposition rate. The methodology is first tested into a three-field approach CFD model.
Estudio Psicométrico del Índice de Carga Mental NASA-TLX con una Muestra de Trabajadores Españoles
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Eva Díaz Ramiro
2010-01-01
Full Text Available El objetivo de este estudio fue evaluar las propiedades psicométricas del instrumento de evaluación de la carga mental de trabajo NASA-TLX en distintos grupos profesionales españoles. La muestra estuvo formada por 398 trabajadores que pertenecían a siete sectores profesionales diferentes. Todos los trabajadores evaluaron la carga mental percibida en sus puestos de trabajo, debida a cada una de las seis dimensiones de carga que distingue el NASA-TLX: esfuerzo, demanda mental, demanda física, demanda temporal, rendimiento y frustración. Los resultados mostraron una consistencia interna aceptable y una estructura factorial constituida por dos factores. Uno de los factores estaba formado únicamente por la dimensión "frustración", mientras que el otro factor englobaba a las cinco dimensiones restantes. Por último, se encontraron diferencias importantes en los perfiles de carga mental entre los grupos profesionales considerados, en todas las dimensiones de carga, excepto en rendimiento.
Overview of hypersonic CFD code calibration studies
Miller, Charles G.
1987-01-01
The topics are presented in viewgraph form and include the following: definitions of computational fluid dynamics (CFD) code validation; climate in hypersonics and LaRC when first 'designed' CFD code calibration studied was initiated; methodology from the experimentalist's perspective; hypersonic facilities; measurement techniques; and CFD code calibration studies.
Auscultación y pruebas de carga
Sánchez García, Ibán
2011-01-01
[ES] Trata sobre la auscultación de estructuras. Los diferentes tipos de pruebas de carga,en puentes de carretera y en puentes de ferrocarril, además de los aparatos de medida y forma de ejecutarlas. [EN] Explains auscultation of structures. The different types of load tests on road bridges and railway bridges, plus the measuring apparatus and method of executing them. Proyecto Fin de Carrera-Universidad de Salamanca, Escuela Politécnica Superior de Zamora, 2011
CFD Studies on Biomass Thermochemical Conversion
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Lifeng Yan
2008-06-01
Full Text Available Thermochemical conversion of biomass offers an efficient and economically process to provide gaseous, liquid and solid fuels and prepare chemicals derived from biomass. Computational fluid dynamic (CFD modeling applications on biomass thermochemical processes help to optimize the design and operation of thermochemical reactors. Recent progression in numerical techniques and computing efficacy has advanced CFD as a widely used approach to provide efficient design solutions in industry. This paper introduces the fundamentals involved in developing a CFD solution. Mathematical equations governing the fluid flow, heat and mass transfer and chemical reactions in thermochemical systems are described and sub-models for individual processes are presented. It provides a review of various applications of CFD in the biomass thermochemical process field.
Aplicación mediante ordenador del factor de acoplamiento en equipos de carga y transporte
Ballester Muñoz, Francisco; Peral San Emeterio, Ángel
1988-01-01
RESUMEN. La coordinación entre los equipos de carga y transporte de materiales, es muy importante en los trabajos de movimiento de tierras, siendo el número de elementos y las dimensiones de los equipos de carga y transporte los factores básicos a determinar en todo proceso de optimización de operaciones, para lo cual se presenta un programa inforrnático de aplicación práctica.
Integrating CFD and building simulation
DEFF Research Database (Denmark)
Bartak, M.; Beausoleil-Morrison, I.; Clarke, J.A.
2002-01-01
Commission, which furthered the CFD modelling aspects of the ESP-r system. The paper summarises the form of the CFD model, describes the method used to integrate the thermal and 3ow domains and reports the outcome from an empirical validation exercise. © 2002 Published by Elsevier Science Ltd....
Melcher, Kevin J.
1997-01-01
The NASA Lewis Research Center is developing analytical methods and software tools to create a bridge between the controls and computational fluid dynamics (CFD) disciplines. Traditionally, control design engineers have used coarse nonlinear simulations to generate information for the design of new propulsion system controls. However, such traditional methods are not adequate for modeling the propulsion systems of complex, high-speed vehicles like the High Speed Civil Transport. To properly model the relevant flow physics of high-speed propulsion systems, one must use simulations based on CFD methods. Such CFD simulations have become useful tools for engineers that are designing propulsion system components. The analysis techniques and software being developed as part of this effort are an attempt to evolve CFD into a useful tool for control design as well. One major aspect of this research is the generation of linear models from steady-state CFD results. CFD simulations, often used during the design of high-speed inlets, yield high resolution operating point data. Under a NASA grant, the University of Akron has developed analytical techniques and software tools that use these data to generate linear models for control design. The resulting linear models have the same number of states as the original CFD simulation, so they are still very large and computationally cumbersome. Model reduction techniques have been successfully applied to reduce these large linear models by several orders of magnitude without significantly changing the dynamic response. The result is an accurate, easy to use, low-order linear model that takes less time to generate than those generated by traditional means. The development of methods for generating low-order linear models from steady-state CFD is most complete at the one-dimensional level, where software is available to generate models with different kinds of input and output variables. One-dimensional methods have been extended
Una reseña de ensayos de carga no destructivos usados para la evaluación de puentes
Jáuregui, David
2001-01-01
El objetivo principal de este artículo es de proveer un breve repaso de la actividad relacionada con la evaluación experimental de los puentes en los Estados Unidos. Los dos métodos de evaluación de carga aplicados por AASHTO (La Asociación Americana de Oficiales de Carreteras Estatales y Transporte) son presentados incluyendo el esfuerzo permisible (AS) y el factor de carga (LF). Además, son discutidos los detalles básicos de los dos tipos de ensayos de carga más comunes para la evaluación d...
Análisis de estabilidad de una línea de transmisión con carga no lineal
Rodríguez Lozoya, Rito Javier
2006-01-01
El propósito de este trabajo es presentar un estudio sobre la estabilidad de una línea de transmisión con carga no lineal, en dos modalidades, la primera como una línea con parámetros concentrados y la segunda como una línea con parámetros distribuidos. Para ambos casos se utiliza la misma carga, un diodo tunel, ya que por sus características de ser un oscilador no lineal con múltiples puntos de equilibrio, representa un buen ejemplo para simular una carga no lineal en un...
Carga mental en la mujer trabajadora: desigualdad de género y prevalencia
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M.ª Carmen Fernández Felipe
2015-03-01
Full Text Available Introducción: La igualdad de género hay sido una preocupación introducida en los últimos años por instituciones tanto internacionales como nacionales. La cuestión de igualdad afecta también al ámbito laboral tanto en lo que se refiere a la distribución del trabajo como a la exposición a riesgos psicosociales, principalmente en economías basadas en la información y conocimiento. Los objetivos de este estudio se dirigen a identificar, entre la población trabajadora española, situaciones de desigualdad entre géneros en lo que se refiere a los diferentes componentes de la carga mental y estimar su prevalencia. Material y métodos: Se realizó un estudio observacional de tipo transversal a partir de los datos recogidos de la «VII Encuesta Nacional de Condiciones del Trabajo» con una muestra de 8.892 trabajadores. Los datos se analizaron de forma bivariante utilizándose el test de Chi-Cuadrado para las variables cualitativas y el t-test para muestras independientes en el caso de variables cuantitativas. La significación se consideró con p < 0,05. Con el objeto de analizar la influencia de distintos factores potencialmente relacionados con componentes de la carga mental y su interacción, se realizó un análisis de regresión logística binaria con el método de inclusión retroceder por paso (Wald. Resultados: Los hombres manifiestan sufrir una menor carga mental que la mujer en relación con el ritmo de trabajo, OR = 0,89 (0,8-0.9, la prevalencia de un «Alto ritmo de trabajo» fue de (0,65‰ en mujeres con respecto a un 0,63‰ en hombres. Los hombres refirieron una menor carga mental por «exceso de trabajo» con respecto a las mujeres OR = 0,9 (0,8-1,0. Las mujeres con mayor frecuencia que el hombre se encuentran fatigadas por una sobrecarga de trabajo (0,37‰ 0,35‰ respectivamente. Conclusiones: Estos resultados no corroboran nuestra hipótesis inicial de que la mujer está expuesta a una mayor carga mental que el hombre
The intangible legacy of the Indonesian Bajo
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Chandra Nuraini
2016-05-01
Full Text Available The Sama-Bajau, or Bajo diaspora, extends from the southern Philippines and Sabah (Malaysian Borneo to the eastern part of Indonesia. The Indonesian Bajo, now scattered along the coasts of Sulawesi (Celebes and East Kalimantan, the Eastern Lesser Sunda Islands and Maluku, were once mostly nomadic fishermen of the sea or ocean freight carriers. Today, the Bajo are almost all fishermen and settled. Their former and present ways of life made them favour intangible forms of culture: it is impossible to transport bulky artefacts when moving frequently by boat, or when living in stilt houses, very close to the sea or on a reef. It is therefore an intangible legacy that is the essence of the Bajo’s culture. Sandro healers have a vast range of expertise that allows them to protect and heal people when they suffer from natural or supernatural diseases. On the other hand, music and especially oral literature are very rich. In addition to song and the pantun poetry contests, the most prestigious genre is the iko-iko, long epic songs that the Bajo consider to be historical rather than fictional narratives. The Bajo’s intangible heritage is fragile, since it is based on oral transmission. In this article, I give a description of this heritage, dividing it into two areas: the knowledge that allows them to “protect and heal” on the one hand, and to “distract and relax”, on the other.
Floriu00E1n Rosa Martu00EDnez Perdomo
2009-01-01
El artículo presenta un análisis del sistema de transporte de carga en la Ciudad de México desde el punto de vista sistémico, considerando las variables económicas, políticas, técnicas, sociales que permitan comprender la problemática que actualmente enfrenta esta ciudad en la movilidad de mercancías. Es una reflexión de carácter multidisciplinario basada en el método cualitativo para explicar y comprender la situación actual del transporte de carga en México dentro del contexto de la globali...
International Nuclear Information System (INIS)
2007-01-01
Computational Fluid Dynamics (CFD) is to an increasing extent being adopted in nuclear reactor safety analyses as a tool that enables specific safety relevant phenomena occurring in the reactor coolant system to be better described. The Committee on the Safety of Nuclear Installations (CSNI), which is responsible for the activities of the Nuclear Energy Agency that support advancing the technical base of the safety of nuclear installations, has in recent years conducted an important activity in the CFD area. This activity has been carried out within the scope of the CSNI working group on the analysis and management of accidents (GAMA), and has mainly focused on the formulation of user guidelines and on the assessment and verification of CFD codes. It is in this GAMA framework that the present workshop was organized and carried out. The purpose of the workshop was to provide a forum for numerical analysts and experimentalists to exchange information in the field of NRS-related activities relevant to CFD validation, with the objective of providing input to GAMA CFD experts to create a practical, state-of-the-art, web-based assessment matrix on the use of CFD for NRS applications. Numerical simulations with a strong emphasis on validation were welcomed in such areas as heat transfer, buoyancy, stratification, natural circulation, free-surface modelling, turbulent mixing and multi-phase flow. These would relate to such NRS-relevant issues as: pressurized thermal shocks, boron dilution, hydrogen distribution, induced breaks, thermal striping, etc. The use of systematic error quantification and Best Practice Guidelines was encouraged. Papers reporting experiments providing high-quality data suitable for CFD validation, specifically in the area of NRS, were given high priority. Here, emphasis was placed on the availability of local measurements, especially multi-dimensional velocity measurements obtained using such techniques as laser-doppler velocimetry, hot
Nuevo modelo matemático para la distribución de carga en el horno alto
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Jiménez, J.
1998-05-01
Full Text Available A mathematical model for burden distribution in the blast furnace, has been developed. A set of operational variables related with the charging system (Paul Wurth plus other parameters related with the burden itself, such as ore and coke repose angles, weights discharged and the effect of the uprising gas, have been taken into account. These data are processed by modern computer tools. As a result, the burden distribution inside the blast furnace is obtained. Every time that a charge is added to the blast furnace, the model updates the burden distribution. The approach employed is based on considering each burden layer described by a set of interrelated polynomials. It has been tested comparing its results with burden layers obtained in a physical model of the blast furnace (scale 1/10. After installation in Aceralia blast furnace B control computers, the model is currently being employed as a tool for process control.
El modelo matemático desarrollado describe la distribución de carga en el tragante de un horno alto. Se ha empleado un conjunto de variables operacionales relacionadas con el sistema de carga (Paul Wurth, junto con otras obtenidas de la carga, tales como el peso descargado, los ángulos de reposo de los materiales y el efecto del gas al atravesar el horno. Estos datos se procesan mediante herramientas informáticas. Como resultado, se obtiene la distribución de carga en el horno. Cada vez que se introduce una carga, el modelo actualiza la distribución. La aproximación empleada considera el perfil de cada capa de carga, el cual está descrito por un conjunto de polinomios interrelacionados. Los resultados se comparan con la distribución obtenida en un modelo físico del horno (escala 1/10. Tras su instalación en los ordenadores de proceso del horno alto B de Aceralia, el modelo se emplea actualmente para el control del mismo.
Application of CFD in Indonesian Research: A review
Ambarita, H.; Siregar, M. R.; Kishinami, K.; Daimaruya, M.; Kawai, H.
2018-04-01
Computational Fluid Dynamics (CFD) is a numerical method that solves fluid flow and related governing equations using a computational tool. The studies on CFD, its methodology and its application as a research tool, are increasing. In this study, application of CFD by Indonesian researcher is briefly reviewed. The main objective is to explore the characteristics of CFD applications in Indonesian researchers. Considering the size and reputation, this study uses Scopus publications indexed data base. All of the documents in Scopus related to CFD which is affiliated by at least one of Indonesian researcher are collected to be reviewed. Research topics, CFD method, and simulation results are reviewed in brief. The results show that there are 260 documents found in literature indexed by Scopus. These documents divided into research articles 125 titles, conference paper 135 titles, book 1 title and review 1 title. In the research articles, only limited researchers focused on the development of CFD methodology. Almost all of the articles focus on using CFD in a particular application, as a research tool, such as aircraft application, wind power and heat exchanger. The topics of the 125 research articles can be divided into 12 specific applications and 1 miscellaneous application. The most popular application is Heating Ventilating and Air Conditioning and followed by Reactor, Transportation and Heat Exchanger applications. The most popular commercial CFD code used is ANSYS Fluent and only several researchers use CFX.
Directory of Open Access Journals (Sweden)
Arias, A.
2004-04-01
Full Text Available A polymeric material loaded with ceramic particles was developed and its static and impact behaviors were determined. A vinylester resin, used as matrix, was reinforced with alumina or silicon carbide particles. These particles, with mean sizes between 1.5 and 4.5 mm, are cheap and readily obtainable. The manufacturing process produced tiles with a high percentage of ceramic particles (up to 80% by weight and low porosity. The static compressive behavior of the composite was examined to consider various factors: ceramic fraction, particle size, material of particles and temperature. A higher volumetric fraction of particles produces an increase of stiffness and raises the yield stress of the composite; the influence of size of particles is not determinant. High temperatures produces a decrease of the mechanical properties. The efficiency of this low-cost material is halfway between that of the conventional metallic materials and the monolithic ceramic tiles used in lightweight protection.
En este trabajo se presenta el proceso de fabricación de un material compuesto de matriz polimérica y carga cer��mica, su caracterización mecánica estática y su comportamiento frente a impacto. Como matriz se ha empleado una resina viniléster y como carga cerámica se han empleado partículas de alúmina y carburo de silicio. Estas partículas, con un tamaño medio comprendido entre 1.5 mm y 4.5 mm, presentan bajo coste y alta disponibilidad. La compactación uniaxial permitió obtener losetas con un elevado porcentaje de partículas cerámicas (hasta el 80% en peso y baja porosidad. Se han realizado ensayos de compresión estática sobre el material desarrollado para analizar la influencia de varios factores: fracción volumétrica de partículas, tamaño de partícula, material de las partículas y temperatura. La resistencia a compresión cuasiestática del nuevo material compuesto se incrementa al aumentar la fracción volumétrica de part
Energy Technology Data Exchange (ETDEWEB)
Tanioka, T [Mitsubishi Heavy Industries, Ltd., Tokyo (Japan)
1990-09-01
The present and future were reviewed of CFD (computational fluid dynamics) technology in Nagoya Works, Mitsubishi Heavy Industries, Ltd., Japan. The progress of the role of CFD in aerodynamic design and progress of CFD technology were reviewed. The followings were illustrated as examples of CFD analysis: design of a main wing for transonic private aircrafts by backward analysis, analysis of an airframe shape for the MU300 jet airplane with a panel method, Navier-stokes (NS) analysis of a transonic wing section, NS analysis of pressure distributions on the surfaces of the YXX airplane and space shuttle HOPE, and NS analysis of an aerodynamic heating distribution for spaceplanes. CFD tools were outlined for every developmental item such as a main wing, and requirements and subjects in practical use were discussed of several CFD tools for a rough check, precise performance check and parametric study. Such computer performance as a main memory capacity and processing speed required for the future practical use of advanced CFD was also discussed. 20 figs.
Directory of Open Access Journals (Sweden)
Alexandre Pazetto Balsanelli
2009-02-01
Full Text Available This study aims to explore the association between nurses' leadership styles and personal and professional nursing profile and workload. The sample consisted of seven nurses and seven nursing technicians who were grouped into pairs. At the end of three months, nurses were queried regarding what leadership style would be adopted when the nursing technician under their evaluation delivered care to patients admitted to the ICU. Relevant data was analyzed by applying descriptive statistics, Tukey's multiple comparison test and Student's t-test (p0.05. The determine, persuade, and share leadership styles prevailed. However, whenever the nursing workload peaked, the determine and persuade styles were used (pEste estudio tuvo como objetivos verificar a relación que existe entre los estilos de liderazgo de los enfermeros con el perfil personal, profesional y carga de trabajo de enfermería. La muestra fue constituida por siete enfermeros y siete técnicos de enfermería que formaron parejas. Durante tres meses los enfermeros fueron cuestionados sobre cual sería el estilo de liderazgo adoptado cuando el técnico de enfermería, bajo su evaluación, prestase cuidados a los pacientes admitidos en la Unidad de Terapia Intensiva. Los datos fueron analizados aplicándose estadística descriptiva, el método de comparaciones múltiples de Tukey y la prueba t de Student (0,05. Los estilos de liderazgo: determinar, persuadir y compartir fueron los predominantes, sin embargo, cuando la carga de trabajo de enfermería era mayor, se observaron los estilos determinar y persuadir (pEste estudo teve como objetivos verificar a relação dos estilos de liderança de enfermeiros com perfil pessoal e profissional e carga de trabalho de enfermagem. A amostra foi constituída por sete enfermeiros e sete técnicos de enfermagem que formaram duplas. Durante três meses os enfermeiros foram questionados sobre qual estilo de liderança seria adotado quando o técnico de
Monitoramento da carga interna de treinamento em jogadores de futsal ao longo de uma temporada
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Bernardo Miloski
2012-10-01
Full Text Available http://dx.doi.org/10.5007/1980-0037.2012v14n6p671 Existe a necessidade de estudos sobre métodos para controle da carga e descrição da periodização em equipes de futsal. O objetivo do estudo foi descrever e analisar a carga interna de treinamento em um macrociclo de futsal utilizando-se o método de Percepção Subjetiva do Esforço da sessão. A amostra foi composta por 13 atletas de Liga Nacional. Calculou-se carga de treinamento semanal total (CTST, monotonia e strain durante 37 semanas. Utilizando Teste t de Student pareado, o período de preparação (PP apresentou CTST, strain e monotonia maiores que o competitivo (PC. Utilizando ANOVA de medidas repetidas, seguida pelo post-hoc de Bonferroni, observaram-se diferenças significativas para CTST entre mesociclos: 1 > 2, 4, 5, 6, 8, 9; 7 > 4, 5, 8, 9; 2, 3 e 6 > 5, 8, 9; 4 > 5; 8 > 5 (p>0,05. As cargas de treinamento (CT foram mais elevadas no PP com redução no PC. A CT apresenta uma característica ondulatória, adaptando-se ao calendário competitivo.
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Luis Macea
2015-01-01
Full Text Available Para el adecuado dimensionamiento de las estructuras de pavimento, se requiere la estimación de los efectos agrupados de las cargas del tránsito, por lo cual se debe conocer el número y tipo de vehículos que circularán por la vía, así como la intensidad del peso y la configuración del eje que la aplica, aspecto que es abordado cuando se hace la caracterización del tránsito a través de espectros de carga. En razón de esto en el presente artículo se construyen espectros de la capacidad por tipo de eje de camiones para diferentes rutas y departamentos de la región andina colombiana, de igual forma se Identifican los porcentajes de sobrecarga y las zonas donde se sobrepasa el límite máximo de peso permitido, así como los tipos de productos transportados en condiciones de exceso de peso. Para esto, se realizaron veintiséis (26 operativos de pesaje móvil de camiones en distintos corredores de carga de la región andina en el año 2013, con lo cual se obtuvo una muestra de 94.132 ejes pesados, a partir de los cuales se agruparon las capacidades por cada tipo de eje y se determinaron sus respectivas frecuencias de arrumaje. Los resultados encontrados indicaron que el eje sencillo direccional de llanta sencilla presenta un solo pico máximo con cierto grado de asimetría, el cual se encuentra regularmente por debajo de la carga máxima legal establecida para este tipo de eje, Por otro lado, los ejes sencillo de llanta doble presentan una bimodalidad con dos picos máximos muy parejos, uno en el sentido de las cargas bajas y el otro en el sentido de las cargas altas, mientras que los ejes tándem y tridem de llanta doble presentan una bimodalidad caracterizada por el predominio de un pico máximo absoluto del lado de las cargas altas lo que indica que los camiones están circulando con carga al límite permitido.
A supportive architecture for CFD-based design optimisation
Li, Ni; Su, Zeya; Bi, Zhuming; Tian, Chao; Ren, Zhiming; Gong, Guanghong
2014-03-01
Multi-disciplinary design optimisation (MDO) is one of critical methodologies to the implementation of enterprise systems (ES). MDO requiring the analysis of fluid dynamics raises a special challenge due to its extremely intensive computation. The rapid development of computational fluid dynamic (CFD) technique has caused a rise of its applications in various fields. Especially for the exterior designs of vehicles, CFD has become one of the three main design tools comparable to analytical approaches and wind tunnel experiments. CFD-based design optimisation is an effective way to achieve the desired performance under the given constraints. However, due to the complexity of CFD, integrating with CFD analysis in an intelligent optimisation algorithm is not straightforward. It is a challenge to solve a CFD-based design problem, which is usually with high dimensions, and multiple objectives and constraints. It is desirable to have an integrated architecture for CFD-based design optimisation. However, our review on existing works has found that very few researchers have studied on the assistive tools to facilitate CFD-based design optimisation. In the paper, a multi-layer architecture and a general procedure are proposed to integrate different CFD toolsets with intelligent optimisation algorithms, parallel computing technique and other techniques for efficient computation. In the proposed architecture, the integration is performed either at the code level or data level to fully utilise the capabilities of different assistive tools. Two intelligent algorithms are developed and embedded with parallel computing. These algorithms, together with the supportive architecture, lay a solid foundation for various applications of CFD-based design optimisation. To illustrate the effectiveness of the proposed architecture and algorithms, the case studies on aerodynamic shape design of a hypersonic cruising vehicle are provided, and the result has shown that the proposed architecture
Safety Injection Tank Performance Analysis Using CFD
Energy Technology Data Exchange (ETDEWEB)
Cho, Jai Oan; Lee, Jeong Ik; Nietiadi Yohanes Setiawan [KAIST, Daejeon (Korea, Republic of); Addad Yacine [KUSTAR, Abu Dhabi (United Arab Emirates); Bang, Young Seok; Yoo, Seung Hun [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)
2016-10-15
This may affect the core cooling capability and threaten the fuel integrity during LOCA situations. However, information on the nitrogen flow rate during discharge is very limited due to the associated experimental measurement difficulties, and these phenomena are hardly reflected in current 1D system codes. In the current study, a CFD analysis is presented which hopefully should allow obtaining a more realistic prediction of the SIT performance which can then be reflected on 1D system codes to simulate various accident scenarios. Current Computational Fluid Dynamics (CFD) calculations have had limited success in predicting the fluid flow accurately. This study aims to find a better CFD prediction and more accurate modeling to predict the system performance during accident scenarios. The safety injection tank with fluidic device was analyzed using commercial CFD. A fine resolution grid was used to capture the vortex of the fluidic device. The calculation so far has shown good consistency with the experiment. Calculation should complete by the conference date and will be thoroughly analyzed to be discussed. Once a detailed CFD computation is finished, a small-scale experiment will be conducted for the given conditions. Using the experimental results and the CFD model, physical models can be validated to give more reliable results. The data from CFD and experiments will provide a more accurate K-factor of the fluidic device which can later be applied in system code inputs.
Martínez Perdomo, Florián Rosa
2010-01-01
El artículo presenta un análisis del sistema de transporte de carga en la Ciudad de México desde el punto de vista sistémico, considerando las variables económicas, políticas, técnicas, sociales que permitan comprender la problemática que actualmente enfrenta esta ciudad en la movilidad de mercancías. Es una reflexión de carácter multidisciplinario basada en el método cualitativo para explicar y comprender la situación actual del transporte de carga en México dentro del contexto de la globa...
CFD simulation of homogenisation time measured by radiotracers
International Nuclear Information System (INIS)
Thyn, J.; Novy, M.; Zitny, R.; Mostik, M.; Jahoda, M.
2004-01-01
A methodology for CFD (Computational Fluid Dynamics) simulation of radiotracer experiments was suggested. The most important parts of the methodology for validation of CFD results by radiotracers are: a) successful simulation of tracer experiment by CFD code (numerical solution of tracer dispersion in a stirred tank), which results in tracer concentration field at several time intervals; b) post-process data treatment, which uses detection chain description and which enables to simulate the detector measurement of homogenisation time from the tracer concentration field evaluated by CFD code. (author)
User Interface Developed for Controls/CFD Interdisciplinary Research
1996-01-01
The NASA Lewis Research Center, in conjunction with the University of Akron, is developing analytical methods and software tools to create a cross-discipline "bridge" between controls and computational fluid dynamics (CFD) technologies. Traditionally, the controls analyst has used simulations based on large lumping techniques to generate low-order linear models convenient for designing propulsion system controls. For complex, high-speed vehicles such as the High Speed Civil Transport (HSCT), simulations based on CFD methods are required to capture the relevant flow physics. The use of CFD should also help reduce the development time and costs associated with experimentally tuning the control system. The initial application for this research is the High Speed Civil Transport inlet control problem. A major aspect of this research is the development of a controls/CFD interface for non-CFD experts, to facilitate the interactive operation of CFD simulations and the extraction of reduced-order, time-accurate models from CFD results. A distributed computing approach for implementing the interface is being explored. Software being developed as part of the Integrated CFD and Experiments (ICE) project provides the basis for the operating environment, including run-time displays and information (data base) management. Message-passing software is used to communicate between the ICE system and the CFD simulation, which can reside on distributed, parallel computing systems. Initially, the one-dimensional Large-Perturbation Inlet (LAPIN) code is being used to simulate a High Speed Civil Transport type inlet. LAPIN can model real supersonic inlet features, including bleeds, bypasses, and variable geometry, such as translating or variable-ramp-angle centerbodies. Work is in progress to use parallel versions of the multidimensional NPARC code.
CFD for hypersonic airbreathing aircraft
Kumar, Ajay
1989-01-01
A general discussion is given on the use of advanced computational fluid dynamics (CFD) in analyzing the hypersonic flow field around an airbreathing aircraft. Unique features of the hypersonic flow physics are presented and an assessment is given of the current algorithms in terms of their capability to model hypersonic flows. Several examples of advanced CFD applications are then presented.
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YAMILE VALENCIA
2012-01-01
Full Text Available Generalmente las pruebas de carga no hacen parte de la rutina de obras de cimentaciones ejecutadas en Suramérica, y cuando son ejecutadas, el análisis queda restringido a la determinación o estimación de la capacidad de carga de la fundación. No obstante, pueden hacerse otros análisis de modo que el calculista cuente con mayores elementos de juicio en lo referente al comportamiento de la cimentación. El presente articulo muestra un conjunto de análisis complementarios, que pueden ser hechos a partir de los resultados obtenidos para una prueba de carga teniendo en cuenta el comportamiento característico de cada suelo y los mecanismos de interacción entre la estructura de cimentación y el suelo de soporte, a partir del análisis de los resultados de pruebas de carga realizadas sobre pilotes ejecutados con hélice continua.
CFD analysis of poison injection in AHWR calandria
International Nuclear Information System (INIS)
Kansal, A.K.; Kamble, M.T.; Maheshwari, N.K.; Vijayan, P.K.
2014-01-01
The present work intends to give details of design and performance validation of SDS-2. The performance is evaluated on the basis of dispersion of poison in calandria in a given period of time. Location of injection tube and injection holes, size of jet hole and number of holes are some of the design parameters which greatly affect dispersion of poison in calandria. A Computational Fluid Dynamic (CFD) study for axial and radial injection of poison was carried out using open source CFD code OpenFOAM. CFD benchmarking was done using experiments performed by Johari (Johari et al. 1997) to identify suitable turbulence model for this problem. An experimental facility simulating poison injection in moderator in presence of calandria tubes was used to further validate the CFD model is shown in the paper. CFD analysis was carried out for axial as well as radial injection for AHWR geometry. CFD analysis using OpenFOAM has been carried out to study high pressure poison injection for single jet of Shut Down System - 2 (SDS- 2) of Advanced Heavy Water Reactor (AHWR) for various design options. CFD model used in analysis have been validated with experimental data available in literature as well as experiments performed for AHWR specific geometry. Various turbulence models are tested and their adequacy for such flow problems has been established. The CFD model is then used to simulate poison injection for two design options for AHWR and their performance is compared. (author)
La organización social en los barrios bajos
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William Foote Whyte
2010-07-01
Full Text Available
Por mucho tiempo, los sociólogos han estudiado los barrios bajos en términos de desorganización social. El interés en los mismos parece provenir de dos fuentes: una urgencia por promover reformas sociales y un esfuerzo para comprender el proceso de urbanización. Observando el quiebre de los controles del grupo primario en la vida de ciudad, algunos sociólogos han considerado analizar la situación resultante en términos del concepto de desorganización social. Los barrios bajos han sido caracterizados por ciertos sociólogos, como áreas de almas perdidas y misiones, áreas donde individuos y familias viven en intimidad forzada con personas a las cuales normalmente rechazan y evitan; áreas donde no se aprecian estándares de decencia o buena conducta excepto los impuestos por una autoridad externa. Según la opinión de otros sociólogos, los barrios bajos son un área de libertad e individualismo. Harvey Zorbaugh dice que la política en el distrito bajo no es como la política en el distrito de clase media. Como no se ajusta a los estándares de la clase media, no es más que un juego. Más aún, la preocupación con el estudio de la desorganización familiar ha conducido a algunos sociólogos a subestimar cualquier grado de organización que se pueda encontrar en los barrios bajos.
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M. A. Alonso-Díaz
2007-01-01
Full Text Available En el trópico húmedo de Veracruz se estimó la respuesta productiva de una pastura de gramas nativas bajo pastoreo rotacional intensivo, con ganado Cebú Brahman, de junio de 1994 a mayo de 1997, con periodos variables de ocupación (1-3 días y recuperación (10-151 días. Se muestrearon seis divisiones (3.0 ± 0.5 ha/división. La MS presente, antes y después del pastoreo en sequía (marzo-junio; 2,135 y 1,402 kg/ ha, fue inferior a nortes (noviembre-febrero; 2,846 y 1,909 kg/ha y lluvias (julio-octubre; 2,844 y 1,864 kg/ha, sin diferencia entre sí. Se encontraron diferencias para peso vivo del becerro en sequía, lluvias y nortes (71, 142 y 161 kg/cabeza. La carga animal en sequía (2.0 unidades animal [UA = 450 kg de peso vivo]/ha fue inferior a la de nortes (2.4 UA/ha y lluvias (2.3 UA/ha que no difirieron entre sí. La época no afectó el contenido de: proteína cruda de la MS presente antes del pastoreo (9.3 ± 1.7%, los días de recuperación (50 ± 26, el peso vivo de la vaca (397 ± 11 kg/cabeza, la tasa absoluta de crecimiento (41 ± 33 kg MS/ ha/día, la disponibilidad de MS (5.8 ± 2.6 kg MS/100 kg PV, el consumo de materia seca (2.3 ± 1.5 kg MS/100 kg PV y grado de uso de la MS disponible (40 ± 22%. La carga animal media del presente estudio duplicó la tradicional de 1.0 UA/ha para gramas nativas, lo que sugiere un potencial productivo mayor de estas pasturas en la región.
Comparação de diferentes métodos de controle da carga interna em jogadores de voleibol
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Maurício Gattás Bara Filho
2013-04-01
Full Text Available INTRODUÇÃO: A capacidade de monitorar precisamente a carga de treinamento é um importante aspecto para a efetividade da periodização e para a prevenção de efeitos negativos, como a queda no rendimento. OBJETIVOS: Comparar e correlacionar diferentes métodos de controle de carga interna de treinamento em jogadores de voleibol. MÉTODOS: Quinze atletas profissionais de voleibol do sexo masculino, com idade entre 18 e 30 anos, que competiam em níveis estaduais e nacionais, participaram deste estudo. A carga de treino para cada sessão foi calculada utilizando três diferentes métodos: PSE da Sessão, Zonas de FC (TRIMP de Edwards e de Stagno. RESULTADOS: Verificou-se que há correlação positiva e significativa entre o método proposto por Foster, Edwards e Stagno. No entanto, os valores das correlações individuais entre PSE e Edwards (0,451 a 0,670, em geral, foram ligeiramente maiores que os da correlação entre PSE e Stagno (0,206 a 0,597. CONCLUSÃO: O método proposto por Edwards, bem como o método proposto por Foster, melhor refletem as cargas de treino no voleibol, fazendo com que o monitoramento das cargas seja realizado de maneira mais fidedigna e confiável quando realizado por esses dois métodos.
Impact of CGNS on CFD Workflow
Poinot, M.; Rumsey, C. L.; Mani, M.
2004-01-01
CFD tools are an integral part of industrial and research processes, for which the amount of data is increasing at a high rate. These data are used in a multi-disciplinary fluid dynamics environment, including structural, thermal, chemical or even electrical topics. We show that the data specification is an important challenge that must be tackled to achieve an efficient workflow for use in this environment. We compare the process with other software techniques, such as network or database type, where past experiences showed how difficult it was to bridge the gap between completely general specifications and dedicated specific applications. We show two aspects of the use of CFD General Notation System (CGNS) that impact CFD workflow: as a data specification framework and as a data storage means. Then, we give examples of projects involving CFD workflows where the use of the CGNS standard leads to a useful method either for data specification, exchange, or storage.
Aferição dos Valores dos Comprimentos Equivalentes Utilizados na Determinação da Perda de Carga
Soares, Fátima C; Teles, Guilherme C; Russi, Jumar L
2015-01-01
Este trabalho teve como objetivo comparar os resultados de perdas de carga localizadas, em tubulações de PVC, com as obtidas em tubulações com comprimento equivalente à peça. O experimento foi conduzido no Laboratório de Hidráulica da Universidade Federal do Pampa/RS, em uma bancada de tubulações, com diâmetros de 20, 25 e 32 mm, onde foram medidas as perdas de carga em curvas de 90°, cotovelos de 45° e 90° e registros de esfera. Para cada peça, foi determinada a perda de carga gerada pelos r...
Arquitectura para balancear carga dinámica por demanda adaptativa, utilizando CORBA en JAVA-IDL
Jesús Chávez Esparza; Gerardo Rentería Castillo; Francisco Javier Luna Rosas
2008-01-01
En este trabajo desglosaremos la elaboración de una nueva Arquitectura para balancear carga dinámica, por demanda adaptativa, utilizando CORBA en JAVA-IDL. Una arquitectura de balanceo de carga es un sistema que permite distribuir el trabajo computacional entre varias máquinas, con el objetivo de reducir el tiempo de respuesta global del sistema. A través de las pruebas se justifica el uso de la arquitectura y se definen los parámetros a considerar para obtener un óptimo desempeño, refiriéndo...
Requirements for effective use of CFD in aerospace design
Raj, Pradeep
1995-01-01
This paper presents a perspective on the requirements that Computational Fluid Dynamics (CFD) technology must meet for its effective use in aerospace design. General observations are made on current aerospace design practices and deficiencies are noted that must be rectified for the U.S. aerospace industry to maintain its leadership position in the global marketplace. In order to rectify deficiencies, industry is transitioning to an integrated product and process development (IPPD) environment and design processes are undergoing radical changes. The role of CFD in producing data that design teams need to support flight vehicle development is briefly discussed. An overview of the current state of the art in CFD is given to provide an assessment of strengths and weaknesses of the variety of methods currently available, or under development, to produce aerodynamic data. Effectiveness requirements are examined from a customer/supplier view point with design team as customer and CFD practitioner as supplier. Partnership between the design team and CFD team is identified as an essential requirement for effective use of CFD. Rapid turnaround, reliable accuracy, and affordability are offered as three key requirements that CFD community must address if CFD is to play its rightful role in supporting the IPPD design environment needed to produce high quality yet affordable designs.
Hybrid CFD/CAA Modeling for Liftoff Acoustic Predictions
Strutzenberg, Louise L.; Liever, Peter A.
2011-01-01
This paper presents development efforts at the NASA Marshall Space flight Center to establish a hybrid Computational Fluid Dynamics and Computational Aero-Acoustics (CFD/CAA) simulation system for launch vehicle liftoff acoustics environment analysis. Acoustic prediction engineering tools based on empirical jet acoustic strength and directivity models or scaled historical measurements are of limited value in efforts to proactively design and optimize launch vehicles and launch facility configurations for liftoff acoustics. CFD based modeling approaches are now able to capture the important details of vehicle specific plume flow environment, identifY the noise generation sources, and allow assessment of the influence of launch pad geometric details and sound mitigation measures such as water injection. However, CFD methodologies are numerically too dissipative to accurately capture the propagation of the acoustic waves in the large CFD models. The hybrid CFD/CAA approach combines the high-fidelity CFD analysis capable of identifYing the acoustic sources with a fast and efficient Boundary Element Method (BEM) that accurately propagates the acoustic field from the source locations. The BEM approach was chosen for its ability to properly account for reflections and scattering of acoustic waves from launch pad structures. The paper will present an overview of the technology components of the CFD/CAA framework and discuss plans for demonstration and validation against test data.
DEGREDATION PROPERTIES OF REINFORCED CONCRETE WALLS WITH OPENINGS
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JULIAN CARRILLO
2011-01-01
Full Text Available En este artículo se compara el comportamiento de cuatro muros aislados de concreto reforzado (CR con aberturas: dos muros prototipo ensayados bajo carga cuasi-estática cíclica (CEC y dos muros ensayados bajo excitación de mesa vibratoria. Las variables estudiadas fueron la cuantía de acero en el alma, el tipo de acero de refuerzo en el alma y el método de ensaye. A partir de la respuesta medida se verificó que la historia de carga de los ensayos CEC ignora los efectos dinámicos fundamentales observados en estructuras sometidas a cargas sísmicas. Cuando las respuestas dinámicas y CEC cíclicas se compararon, se observó que las propiedades de degradación de rigidez y resistencia dependen de la velocidad de aplicación de carga, los mecanismos de resistencia asociados a los modos de falla, el número de ciclos y los parámetros acumulados de la demanda de ductilidad y energía disipada. Por lo tanto, los datos obtenidos a partir de ensayos CEC no siempre se pueden suponer de forma segura como un límite inferior de la capacidad esperada. En el artículo también se proponen modelos de degradación de rigidez y resistencia para muros de CR con aberturas sometidos a carga del tipo sísmica.
Una estrategia evolutiva de predicción para balance de carga en entornos de sistemas distribuidos
Esquivel, Susana Cecilia; Leguizamón, Guillermo
1996-01-01
Este artículo propone. una estrategia evolutiva de predicción, en un entorno de balance de carga, en Sistemas Distribuidos. Los algoritmos de balance de carga intentan mejorar la performance del sistema recurriendo a la migración de procesos, pero presentan el problema adicional de la inestabilidad que ocurre cuando los procesos gastan.una cantidad excesiva de tiempo migrando entre los diferentes nodos del sistema. Con el fin de disminuir el tráfico de.comunicaciones generadas por la es...
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Roseli Schmoeller
2011-06-01
Full Text Available O presente estudo teve por objetivo conhecer a produção teórica sobre cargas de trabalho e condições de trabalho dos profissionais de enfermagem. Para tanto, foi realizada uma revisão integrativa que incluiu artigos científicos, teses e dissertações, indexados nas bases da Biblioteca Virtual de Saúde e Banco Digital de Teses nos últimos dez anos. Entre os 132 trabalhos identificados, foram selecionadas 27 produções. Os resultados indicaram as cargas de trabalho como responsáveis pelo desgaste dos profissionais, influenciando a ocorrência de acidentes e os problemas de saúde. Para amenizar tais cargas de trabalho, os estudos apontam algumas estratégias, como adequação do quantitativo de pessoal, educação continuada e melhores condições de trabalho. Tem-se como desafio a realização de pesquisas que revelem com mais precisão a relação entre as cargas e as condições de trabalho da equipe de enfermagem, haja vista o quanto comprometem a saúde dos trabalhadores.Estudio que objetivó conocer la producción teórica sobre las cargas de trabajo y condiciones de trabajo de profesionales de enfermería. Para eso, se realizó una revisión integradora que incluyó artículos científicos, tesis o disertaciones, indexados en bases de Biblioteca Virtual de Salud y Banco Digital de Tesis en los últimos diez años. Entre los 132 trabajos identificados, fueron seleccionadas 27 producciones. Los resultados indicaron las cargas de trabajo como responsables por el desgaste de los profesionales, influenciando la ocurrencia de accidentes y problemas de salud. Para amenizar esas cargas de trabajo los estudios apuntan algunas estrategias: adecuación del cuantitativo de personal, educación continuada y mejores condiciones de trabajo. Se tiene el desafío de la realización de pesquisas que revelen con mayor precisión la relación entre las cargas de trabajo y las condiciones de trabajo de la equipe de enfermería, consider
CARACTERIZACIÓN DE CARGAS DE BAILE EN UNA PLATAFORMA EXPERIMENTAL
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Diana Carolina Millán Yusti
2013-12-01
Full Text Available La utilización de materiales ligeros y resistentes ha permitido la construcción de sistemas de entrepisos que satisfacen condiciones ideales espaciales y geométricas para albergar grandes cantidades de personas. A pesar que estas características de peso y resistencia representan una disminución de costos en la construcción, estos entrepisos tienden a ser más susceptibles a presentar problemas de vibraciones, especialmente cuando la excitación puede ser clasificada como actividad rítmica. En este artículo se presenta la caracterización de cargas producidas por personas realizando actividades de baile, a partir de mediciones en una plataforma experimental de escala real. Se identifican los factores de impacto y coeficientes de Fourier que representan la carga debida a personas que bailan, a la que es sometida la estructura. Los resultados de la presente investigación fueron obtenidos dentro de un proyecto de investigación financiado por Colciencias y la Universidad del Valle contrato .382-2009.
Recent developments in CFD and their impact on fuel assembly optimization
International Nuclear Information System (INIS)
Lascar, Celine; Alleborn, Norbert; Leberig, Mario; Jones, J.; Martin, M.
2010-01-01
In the recent past, progress in computer hardware and in Computational Fluid Dynamics (CFD) codes has made CFD attractive for thermal-hydraulic applications of the nuclear industry. Available code systems have a separated treatment of 1-phase and 2-phase CFD. While 1-phase phenomena (relevant for example to determine pressure losses in fuel assembly) can be reliably predicted with today's CFD programs, 2-phase CFD is still in the process of strong development in modeling 2- phase phenomena. AREVA NP is investing major efforts and resources (i) to develop knowledge and mastery of CFD models, their associated parameters, and the ranges of applications; (ii) to ensure validation of the in-house CFD codes and methodologies by gathering a large experimental databank; and (iii) to build state-ofthe- art tools and hardware to support this CFD development. All CFD work presented in this paper was performed with the commercial code STAR-CD. (orig.)
Groves, Curtis E.; LLie, Marcel; Shallhorn, Paul A.
2012-01-01
There are inherent uncertainties and errors associated with using Computational Fluid Dynamics (CFD) to predict the flow field and there is no standard method for evaluating uncertainty in the CFD community. This paper describes an approach to -validate the . uncertainty in using CFD. The method will use the state of the art uncertainty analysis applying different turbulence niodels and draw conclusions on which models provide the least uncertainty and which models most accurately predict the flow of a backward facing step.
Nonlinear dynamics and numerical uncertainties in CFD
Yee, H. C.; Sweby, P. K.
1996-01-01
The application of nonlinear dynamics to improve the understanding of numerical uncertainties in computational fluid dynamics (CFD) is reviewed. Elementary examples in the use of dynamics to explain the nonlinear phenomena and spurious behavior that occur in numerics are given. The role of dynamics in the understanding of long time behavior of numerical integrations and the nonlinear stability, convergence, and reliability of using time-marching, approaches for obtaining steady-state numerical solutions in CFD is explained. The study is complemented with spurious behavior observed in CFD computations.
Metodología de la sumatoria de las curvas de cargas
Directory of Open Access Journals (Sweden)
Elena Llimó Bravo
2011-02-01
Full Text Available Se describe la metodología para la sumatoria de la curvas de carga con la cual se puede determinar lacurva de carga estimada en un equipo o cualquier punto de una red de distribución, mediante el empleo dela base de datos de las curvas diarias representativas de cada una de los diferentes tipos de consumidores( residencial, comercial e industrial , y su consumo mensual (kWh/mensual. Toda esta información esguardada en una base de datos para ser utilizada en estudios de planeamiento e ingeniería. This paper present a methodology for the aggregation load curves , to determine the expected loading inequipment or in a present part of the distribution network by using the representative daily curves database of each consumer's activity (residential, commercial and industrial and the monthly energyconsumption (kWh/monthly. All the information is stored in database and is used for planning an engineeringstudies.
Computational System For Rapid CFD Analysis In Engineering
Barson, Steven L.; Ascoli, Edward P.; Decroix, Michelle E.; Sindir, Munir M.
1995-01-01
Computational system comprising modular hardware and software sub-systems developed to accelerate and facilitate use of techniques of computational fluid dynamics (CFD) in engineering environment. Addresses integration of all aspects of CFD analysis process, including definition of hardware surfaces, generation of computational grids, CFD flow solution, and postprocessing. Incorporates interfaces for integration of all hardware and software tools needed to perform complete CFD analysis. Includes tools for efficient definition of flow geometry, generation of computational grids, computation of flows on grids, and postprocessing of flow data. System accepts geometric input from any of three basic sources: computer-aided design (CAD), computer-aided engineering (CAE), or definition by user.
Energy Technology Data Exchange (ETDEWEB)
Morales Gonzalez, Eduardo
2005-12-15
Environmental and economic reasons have been the main factors for limiting the growing of transmission power grids in many countries. In addition, the electric industry trend to de-regulation of electricity markets has forced to operate the transmission grids closer to their normal limits for secure operation. Since most of the time modern power networks operate under stressed conditions, voltage collapse has become a big concern in the daily operation of the systems. Thus, determination of reliable operating limits respect to voltage collapse is of utmost importance to guarantee an economical and secure system operation. With the aim of understanding the mechanisms of voltage stability and voltage collapse, a number of studying approaches have been proposed for the analysis of such problems. A common feature of those approaches is the importance of reliable models for representing load characteristics. As a result of this, the development of adequate mathematical models for reliable load representation has received a great deal of attention. Despite those efforts, load modeling remains as a big challenge in the analysis of power systems voltage stability. In this thesis, the influence of load modeling on voltage stability is addressed using a steady-state analysis approach. The voltage stability analysis of the system is performed from the P-V curves for different load representations and voltage sensitivity indices. Finally, numerical results from two test systems are reported and the close relationship between load modeling and voltage stability limits in a power system is highlighted. [Spanish] Las razones economicas y ambientales han sido los principales factores para limitar el crecimiento de los sistemas de transmision en muchos paises. Ademas, la tendencia a la desregulacion en la industria electrica ha forzado a operar las redes electricas mas cerca de sus limites de operacion. Debido a que la mayoria de los sistemas electricos modernos operan bajo
U.S. Environmental Protection Agency — Data associated with the development of the CFD model for spore deposition in respiratory systems of rabbits and humans. This dataset is associated with the...
Some Aspects of Nonlinear Dynamics and CFD
Yee, Helen C.; Merriam, Marshal (Technical Monitor)
1996-01-01
The application of nonlinear dynamics to improve the understanding of numerical uncertainties in computational fluid dynamics (CFD) is reviewed. Elementary examples in the use of dynamics to explain the nonlinear phenomena and spurious behavior that occur in numerics are given. The role of dynamics in the understanding of long time behavior of numerical integrations and the nonlinear stability, convergence, and reliability of using time-marching approaches for obtaining steady-state numerical solutions in CFD is explained. The study is complemented with examples of spurious behavior observed in CFD computations.
CFD for wind and tidal offshore turbines
Montlaur, Adeline
2015-01-01
The book encompasses novel CFD techniques to compute offshore wind and tidal applications. Computational fluid dynamics (CFD) techniques are regarded as the main design tool to explore the new engineering challenges presented by offshore wind and tidal turbines for energy generation. The difficulty and costs of undertaking experimental tests in offshore environments have increased the interest in the field of CFD which is used to design appropriate turbines and blades, understand fluid flow physical phenomena associated with offshore environments, predict power production or characterise offshore environments, amongst other topics.
CFD studies on thermal hydraulics of spallation targets
International Nuclear Information System (INIS)
Tak, N.I.; Batta, A.; Cheng, X.
2005-01-01
Full text of publication follows: Due to the fast advances in computer hardware as well as software in recent years, more and more interests have been aroused to use computational fluid dynamics (CFD) technology in nuclear engineering and designs. During recent many years, Forschungszentrum Karlsruhe (FZK) has been actively involved in the thermal hydraulic analysis and design of spallation targets. To understand the thermal hydraulic behaviors of spallation targets very detailed simulations are necessary because of their complex geometries, complicated boundary conditions such as spallation heat distributions, and very strict design limits. A CFD simulation is believed to be the best for this purpose even though the validation of CFD codes are not perfectly completed yet in specific topics like liquid metal heat transfer. The research activities on three spallation targets (i.e., MEGAPIE, TRADE, and XADS targets) are currently very active in Europe in order to consolidate the European ADS road-map. In the thermal hydraulics point of view, two kinds of the research activities, i.e., (1) numerical design and (2) experimental work, are required to achieve the objectives of these targets. It should be noted that CFD studies play important role on both kinds of two activities. A preliminary design of a target can be achieved by sophisticated CFD analysis and pre-and-post analyses of an experimental work using a CFD code help the design of the test section of the experiment as well as the analysis of the experimental results. The present paper gives an overview about the recent CFD studies relating to thermal hydraulics of the spallation targets recently involved in FZK. It covers numerical design studies as well as CFD studies to support experimental works. The CFX code has been adopted for the studies. Main recent results for the selected examples performed by FZK are presented and discussed with their specific lessons learned. (authors)
Directory of Open Access Journals (Sweden)
Magdalena Cortés
2014-01-01
Full Text Available La predicción de patrones de flujo de aire, velocidad, temperatura, humedad y concentración de contaminantes son requeridos para el diseño de ambientes interiores saludables y confortables. La Dinámica de Fluidos Computacional (CFD es la técnica más avanzada para modelar y predecir los flujos de aire en ambientes cerrados. Sin embargo, los principales errores en los modelos CFD y en sus resultados están relacionados con el factor humano. Los principiantes en modelación CFD no cuentan con las habilidades, experiencia y juicio ingenieril para generar modelos robustos y confiables. Este proceso no es intuitivo y los nuevos usuarios necesitan orientación. Este artículo busca proveer información más completa sobre la modelación CFD de casos básicos de convección natural, forzados y mixtos que permitirán a los nuevos usuarios adquirir las habilidades y confianza. La modelación CFD incluye la generación de malla, definición de criterios de convergencia y factores de relajación, y la evaluación de modelos de turbulencia para cada caso. Los resultados muestran que es necesaria la experiencia de los usuarios en cada paso de la modelación CFD, incluso para casos simples de convección.
Influencia de Las Cargas Térmicas Sobre Flujos de Aire Generados en Una Habitacíon
DEFF Research Database (Denmark)
Olmedo, Inés; Ruiz de Adana Santiago, Manuel; Nielsen, Peter V.
2011-01-01
El flujo de aire en el interior de un local generado con un sistema de ventilación y difusión de aire puede verse afectado por las cargas térmicas internas del local. En este trabajo, se estudia la influencia de las cargas térmicas internas debidas a personas en el flujo de aire interior de un lo...... difusor textil de baja velocidad. Los resultados obtenidos pueden resultar de interés para validar las predicciones obtenidas a partir de modelos numéricos de difusores....
Estudo da injeção de carga em nanotubos de carbono por microscopia de força elétrica
Ana Paula Moreira Barboza
2008-01-01
Neste trabalho, serão apresentados os resultados obtidos no Laboratório de Nanoscopia e no Laboratório de Espectroscopia Raman - DF/UFMG a respeito das propriedades elétricas de nanotubos de carbono de parede simples ^Ö CNT investigados por injeção de carga, Microscopia de Força Elétrica (EFM), Espectroscopia Raman e cálculos por primeiros princípios. As injeções de carga foram realizadas pressionando um dado nanotubo com a ponta de EFM com respeito ao substrato. A transferência de carga foi ...
Application of CFD methods in research of SCWR thermo-hydraulics
International Nuclear Information System (INIS)
Zeng Xiaokang; Li Yongliang; Yan Xiao; Xiao Zejun; Huang Yanping
2013-01-01
The CFD method has been an important tool in the research of SCWR thermo- hydraulics. Currently, the CFD methods uses commonly the subcritical turbulence models, which can not accurately simulate the gravity and thermal expansion acceleration effect, and CFD numerical method is not applicable when the heat flux is large. The paper summarizes the application status of the CFD methods in the research of SCWR thermo-hydraulics in RETH. (authors)
Directory of Open Access Journals (Sweden)
Ricardo Adolfo Parra Huertas
2010-06-01
Full Text Available La tecnología de tratamiento anaeróbico se ha desarrollado para el tratamiento de aguas residuales principalmente de origen alimentario. El trabajo tuvo como objetivo determinar el comportamiento del sistema de depuración anaerobio cuando se incorporaban altas cargas puntuales de lactosuero. Se utilizó lactosuero ácido el cual alimentaba un sistema de dos etapas, biofiltro anaerobio y reactor UASB. Se manejaron 3 cargas constantes de 5,200 mg DQO/L.día, 7,800 mg DQO/L.día y 10.500 mg DQO/L.día; en cada carga se aplicaron 3 cargas puntuales de lactosuero ácido: 5,700 mg DQO/L.día, 26,300 mg DQO/L.día y 34.200 mg DQO/L.día, cada una con una duración de 24 horas. El tiempo de retención hidráulico del sistema fue 2,9 días; el valor del pH para la influente de las cargas puntuales y constantes fue de 7,0 previamente añadiéndose bicarbonato de sodio, para la efluente, el pH en las cargas constantes fue 7,6 y 7,7 para las cargas puntuales. La temperatura de operación se mantuvo en un intervalo de 15-20 °C. En las cargas constantes (CC la eliminación de DQO fue 57% y en las cargas puntuales (CP 82%. En azúcares la eficiencia fue 99% en las CC y CP. En proteína la eliminación fue 64% para las CC y CP 89%. Los ácidos grasos volátiles en las CC tuvieron una concentración de 403 mg/L en el influente y en efluente una concentración de 3.156 mg/L, en las CP la influente presentó concentración de 572 mg/L y para el efluente 4.492 mg/L. El sistema de dos etapas soportó las cargas puntuales hasta 6,5 veces la carga constante sin disminuir sus eficiencias, por el contrario las eficiencias en las variable respuesta estuvieron por encima de las cargas orgánicas constantes, observándose que el sistema propuesto es una buena opción para el tratamiento de agua residual con lactosuero pudiendo soportar descargas de lactosuero puro, por lo que puede ser recomendado a los productores de queso.Anaerobic treatment technology was developed
Carga viral para citomegalovirus, en líquido de lavado bronquioalveolar, en población pediátrica
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B H Aristizabal-Bernal
2017-03-01
Full Text Available INTRODUCCIÓN: las infecciones pulmonares son comunes en los pacientes inmunocomprometidos. La carga viral de citomegalovirus se utiliza de rutina para determinar en qué momento se debe iniciar la terapia preventiva en hospederos inmunocomprometidos, diagnosticar enfermedad activa y supervisar la repuesta a una terapia implementada. OBJETIVO: describir el valor de la carga viral de citomegalovirus en líquido de lavado bronquioalveolar vs. sangre periférica en población pediátrica con signos de infección respiratoria. MATERIALES Y MÉTODOS: estudio descriptivo, observacional de 16 pacientes pediátricos y 19 episodios, a quienes se les realizó, de manera simultánea, la carga viral de citomegalovirus en sangre y lavado bronquioalveolar. RESULTADOS Y CONCLUSIONES: todas las cargas virales de citomegalovirus realizadas en lavado bronquioalveolar fueron positivas y en general se obtuvieron valores más elevados que en sangre, lo que sugiere una mayor sensibilidad de la prueba cuando se realiza en este tipo de muestra, en pacientes con sospecha clínica de infección respiratoria por citomegalovirus, lo cual la convierte en una ayuda diagnóstica importante según lo muestran los resultados obtenidos.
Loomans, M.G.L.C.; Lemaire, A.D.; Plas, van der M.
2009-01-01
The paper describes results from a reference study that focuses on the application of the Computational Fluid Dynamics (CFD-) technique for heat and smoke transport in practice. Goal of the study is to obtain insight into the amount and causes of the spread of CFD-results when applied by different
Energy Technology Data Exchange (ETDEWEB)
Rosado Tamariz, Erick
2007-06-15
basicas para el analisis de flujo y el proceso de optimizacion en las turbinas, los cuales consisten en: modelado de flujo a traves de toda la turbina (conjunto), o bien el modelado de cada componente por separado, obteniendo resultados satisfactorios por ambas metodologias. En la mayoria de los casos implementando el metodo de volumen finito (MVF), con consideraciones de flujo no viscoso, con la implementacion de los modelos de dos ecuaciones para la solucion de las ecuaciones que rigen el flujo turbulento. Asi mismo, se utilizan tecnicas de optimizacion que se basan en la parametrizacion geometrica, el planteamiento de una funcion objetivo y en la disminucion del fenomeno de cavitacion. En el presente trabajo se presenta la optimizacion de un rodete de una turbina hidraulica tipo Francis modelo, considerando tres condiciones de carga (75%, 85% y 100%) a traves de la dinamica de fluidos computacionales (CFD) como parte de un analisis hidraulico para la modernizacion de una unidad de generacion de potencia. Se realiza la optimizacion del rodete de una turbina tipo Francis, mediante un analisis previo de CFD mediante el MVF, considerando los efectos viscosos del fluido y el modelo de turbulencia Sparlat-Allmaras; modelando el distribuidor y el rodete por separado. Posteriormente se realiza la generacion de un modelo parametrico del rodete y se configura la simulacion para la generacion de la base de datos. Finalmente se plantea una funcion objetivo para con ello obtener la geometria optima de los alabes del rodete. Los resultados se presentan en forma grafica donde se muestra la distribucion de presiones del rodete original y el rodete optimizado; de igual forma, se comparan las formas geometricas y los resultados globales de desempeno (potencia y rendimiento) de ambos rodetes.
Application of CFD technique for HYFLEX aerodynamic design
Yamamoto, Yukimitsu; Watanabe, Shigeya; Ishiguro, Mitsuo; Ogasawara, Ko; 山本 行光; 渡辺 重哉; 石黒 満津夫; 小笠原 宏
1994-01-01
An overview of the application of Computational Fluid Dynamics (CFD) technique for the HYFLEX (Hypersonic Flight Experiment) aerodynamic design by using the numerical simulation codes in the supersonic and hypersonic speed ranges is presented. Roles of CFD required to make up for the short term of development and small amount of the wind tunnel test cases, application in the HYFLEX aerodynamic design and their application methods are described. The procedure of CFD code validation by the expe...
CFD Modeling of Free-Piston Stirling Engines
Ibrahim, Mounir B.; Zhang, Zhi-Guo; Tew, Roy C., Jr.; Gedeon, David; Simon, Terrence W.
2001-01-01
NASA Glenn Research Center (GRC) is funding Cleveland State University (CSU) to develop a reliable Computational Fluid Dynamics (CFD) code that can predict engine performance with the goal of significant improvements in accuracy when compared to one-dimensional (1-D) design code predictions. The funding also includes conducting code validation experiments at both the University of Minnesota (UMN) and CSU. In this paper a brief description of the work-in-progress is provided in the two areas (CFD and Experiments). Also, previous test results are compared with computational data obtained using (1) a 2-D CFD code obtained from Dr. Georg Scheuerer and further developed at CSU and (2) a multidimensional commercial code CFD-ACE+. The test data and computational results are for (1) a gas spring and (2) a single piston/cylinder with attached annular heat exchanger. The comparisons among the codes are discussed. The paper also discusses plans for conducting code validation experiments at CSU and UMN.
Modelagem e controle de cargas em movimento vertical
Terceiro, Georges Jean Bruel
2004-01-01
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-graduação em Engenharia Elétrica Vários são os aspectos envolvidos no processo de controle de movimento de veículos para deslocamento vertical que tornam o seu estudo interessante, sobretudo quando se trata de elevadores para transporte de pessoas, em que pesa sobremaneira o fato da existência de "cargas" vivas e conscientes. O controle do movimento de equipamentos elevadores é realizado a ...
Directory of Open Access Journals (Sweden)
P. Jiménez-Reyes
2011-01-01
Full Text Available El estudio de la dosificación de la carga siempre ha suscitado controversias y no está resuelta cuál es la carga óptima de entrenamiento para alcanzar el mayor rendimiento. La mayoría de estudios analizan los efectos agudos del entrenamiento y las relaciones entre las variables del entrenamiento de manera sincrónica, sin que exista, en muchos casos, una evidencia científica sobre las cargas más adecuadas y su efecto en el rendimiento. Nuestro objetivo fue proporcionar una información relevante y útil para poder controlar y organizar el entrenamiento de manera racional en atletismo, obteniendo una información más completa y real de los efectos del proceso de entrenamiento. Participaron 24 sujetos que realizaron un seguimiento del control del entrenamiento a través del "Salto con Contramovimiento" (CMJ y la carga de entrenamiento durante 71 semanas. Destacamos la evolución del CMJ y la carga de entrenamiento en las cuatro semanas previas a la competición en la que se obtenía el mejor rendimiento durante las 71 semanas de seguimiento. En conclusión, si se realiza un exhaustivo control de la carga de entrenamiento y su relación con el rendimiento físico y deportivo, permitiría ajustar las cargas de entrenamiento adecuadamente, proporcionando una información relevante y útil para poder organizar el entrenamiento de manera racional.
Condiciones de trabajo, fatiga laboral y bajo peso al nacer en vendedoras ambulantes
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Hernández-Peña Patricia
1999-01-01
Full Text Available Objetivo. Este trabajo tipifica las condiciones demográficas, socioeconómicas, laborales, de fatiga laboral y daño reproductivo en una población femenina en edad fértil que trabaja en la venta ambulante en las calles de la Ciudad de México. Material y métodos. Se entrevistaron 426 vendedoras ambulantes. Se describió a la población entrevistada y se exploró la asociación de los componentes de la fatiga laboral con el bajo peso al nacer (BPN mediante regresión logística, en un subgrupo de mujeres que laboraron en la venta ambulante durante su última gestación. Resultados. De las mujeres entrevistadas, 56% realiza jornadas de trabajo superiores a las 48 horas semanales, 87% carece de seguridad social y 68% tiene estudios no mayores de primaria. El riesgo de presentar BPN se eleva cuando se carece de control sobre la cantidad de mercancía a vender (RM 6.5, IC95% 1.3-31, se venden artículos de ocasión como refacciones y ornamentos (RM 6.3, IC95% 1.5-26, se exhibe la mercancía sobre el piso o se carga para su venta (RM 7.7, IC95% 1.8-32, y cuando los recursos para instalar el puesto por primera vez no proceden de la red social de apoyo de la vendedora (RM 7.4, IC95% 1.2-44. Conclusiones. Estos resultados contribuyen a identificar a las vendedoras con mayor riesgo de presentar un hijo con BPN, y sugerir medidas preventivas.
The Dalles Dam, Columbia River: Spillway Improvement CFD Study
Energy Technology Data Exchange (ETDEWEB)
Cook, Chris B.; Richmond, Marshall C.; Serkowski, John A.
2006-06-01
This report documents development of computational fluid dynamics (CFD) models that were applied to The Dalles spillway for the US Army Corps of Engineers, Portland District. The models have been successfully validated against physical models and prototype data, and are suitable to support biological research and operations management. The CFD models have been proven to provide reliable information in the turbulent high-velocity flow field downstream of the spillway face that is typically difficult to monitor in the prototype. In addition, CFD data provides hydraulic information throughout the solution domain that can be easily extracted from archived simulations for later use if necessary. This project is part of an ongoing program at the Portland District to improve spillway survival conditions for juvenile salmon at The Dalles. Biological data collected at The Dalles spillway have shown that for the original spillway configuration juvenile salmon passage survival is lower than desired. Therefore, the Portland District is seeking to identify operational and/or structural changes that might be implemented to improve fish passage survival. Pacific Northwest National Laboratory (PNNL) went through a sequence of steps to develop a CFD model of The Dalles spillway and tailrace. The first step was to identify a preferred CFD modeling package. In the case of The Dalles spillway, Flow-3D was as selected because of its ability to simulate the turbulent free-surface flows that occur downstream of each spilling bay. The second step in development of The Dalles CFD model was to assemble bathymetric datasets and structural drawings sufficient to describe the dam (powerhouse, non-overflow dam, spillway, fish ladder entrances, etc.) and tailrace. These datasets are documented in this report as are various 3-D graphical representations of The Dalles spillway and tailrace. The performance of the CFD model was then validated for several cases as the third step. The validated model
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Vivian Aline Mininel
2011-04-01
Full Text Available Objective: to identify the work process, the psychic workloads and the strains generated in nursing workers. Method: the study was developed in five Brazilian university hospitals. The sample was composed by 62 nursing workers and the data collection was done by focal group technique, followed by the application of a collective inquire. The data were quantitatively described and systematized according to a thematic analysis. Results: the study population represented 35,37% of the hospital workforce in national setting. The workers mentioned are exposure to several kinds of psychic workload and link them to with others workloads, highlighting the strain processes resulting from this kind of workload, such stress, fatigue, complaints of gastritis and headaches. Conclusions: nursing workers are exposed to several workloads in the hospital environment, especially psychic workloads. This exposure starts strain processes that compromise the health and quality of life, signaling the necessity of interventions in this reality.El objetivo de este estudio fue identificar el proceso de trabajo, las cargas psíquicas y los desgastes generados en trabajadores de enfermería. Se trata de un estudio desarrollado en cinco hospitales universitarios brasileños. La muestra fue compuesta por 62 trabajadores de enfermería; la recolección fue realizada por medio de la técnica de grupo focal, seguida de la aplicación de encuesta colectiva. Los datos fueron descritos numéricamente y sistematizados según análisis temático. La población de estudio representó 35,37% de la fuerza de trabajo hospitalario en el escenario nacional. Los trabajadores refirieron exposición a diversos tipos de cargas psíquicas y las relacionaron con otras cargas de trabajo, destacando los desgastes provenientes de este tipo de carga, como estrés, fatiga, gastritis y cefalea. Los trabajadores de enfermería están expuestos a las diversas cargas de trabajo en el ambiente hospitalario
Tip studies using CFD and comparison with tip loss models
DEFF Research Database (Denmark)
Hansen, Martin Otto Laver; Johansen, J.
2004-01-01
The flow past a rotating LM8.2 blade equipped with two different tips are computed using CFD. The different tip flows are analysed and a comparison with two different tip loss models is made. Keywords: tip flow, aerodynamics, CFD......The flow past a rotating LM8.2 blade equipped with two different tips are computed using CFD. The different tip flows are analysed and a comparison with two different tip loss models is made. Keywords: tip flow, aerodynamics, CFD...
Tracer dispersion - experiment and CFD
International Nuclear Information System (INIS)
Zitny, R.
2004-01-01
Description of tracer distribution by means of dispersion models is a method successfully used in process engineering for fifty years. Application of dispersion models in reactor engineering for characterization of flows in column apparatus, heat exchangers, etc. is summarized and experimental tracer techniques as well as CFD methods for dispersion coefficients evaluation are discussed. Possible extensions of thermal axial dispersion model (ADM) and a core-wall ADM model suitable for description of tracer dispersion in laminar flows are suggested as well as CFD implementation as 1D finite elements. (author)
Retooling CFD for hypersonic aircraft
Dwoyer, Douglas L.; Kutler, Paul; Povinelli, Louis A.
1987-01-01
The CFD facility requirements of hypersonic aircraft configuration design development are different from those thus far employed for reentry vehicle design, because (1) the airframe and the propulsion system must be fully integrated to achieve the desired performance; (2) the vehicle must be reusable, with minimum refurbishment requirements between flights; and (3) vehicle performance must be optimized for a wide range of Mach numbers. An evaluation is presently made of flow resolution within shock waves, transition and turbulence phenomenon tractability, chemical reaction modeling, and hypersonic boundary layer transition, with state-of-the-art CFD.
Validation of NEPTUNE-CFD two-phase flow models using experimental data
International Nuclear Information System (INIS)
Perez-Manes, Jorge; Sanchez Espinoza, Victor Hugo; Bottcher, Michael; Stieglitz, Robert; Sergio Chiva Vicent
2014-01-01
This paper deals with the validation of the two-phase flow models of the CFD code NEPTUNE-CFD using experimental data provided by the OECD BWR BFBT and PSBT Benchmark. Since the two-phase models of CFD codes are extensively being improved, the validation is a key step for the acceptability of such codes. The validation work is performed in the frame of the European NURISP Project and it was focused on the steady state and transient void fraction tests. The influence of different NEPTUNE-CFD model parameters on the void fraction prediction is investigated and discussed in detail. Due to the coupling of heat conduction solver SYRTHES with NEPTUNE-CFD, the description of the coupled fluid dynamics and heat transfer between the fuel rod and the fluid is improved significantly. The averaged void fraction predicted by NEPTUNE-CFD for selected PSBT and BFBT tests is in good agreement with the experimental data. Finally, areas for future improvements of the NEPTUNE-CFD code were identified, too. (authors)
Computational Fluid Dynamics (CFD) applications in rocket propulsion analysis and design
Mcconnaughey, P. K.; Garcia, R.; Griffin, L. W.; Ruf, J. H.
1993-01-01
Computational Fluid Dynamics (CFD) has been used in recent applications to affect subcomponent designs in liquid propulsion rocket engines. This paper elucidates three such applications for turbine stage, pump stage, and combustor chamber geometries. Details of these applications include the development of a high turning airfoil for a gas generator (GG) powered, liquid oxygen (LOX) turbopump, single-stage turbine using CFD as an integral part of the design process. CFD application to pump stage design has emphasized analysis of inducers, impellers, and diffuser/volute sections. Improvements in pump stage impeller discharge flow uniformity have been seen through CFD optimization on coarse grid models. In the area of combustor design, recent CFD analysis of a film cooled ablating combustion chamber has been used to quantify the interaction between film cooling rate, chamber wall contraction angle, and geometry and their effects of these quantities on local wall temperature. The results are currently guiding combustion chamber design and coolant flow rate for an upcoming subcomponent test. Critical aspects of successful integration of CFD into the design cycle includes a close-coupling of CFD and design organizations, quick turnaround of parametric analyses once a baseline CFD benchmark has been established, and the use of CFD methodology and approaches that address pertinent design issues. In this latter area, some problem details can be simplified while retaining key physical aspects to maintain analytical integrity.
MODELO BASEADO EM COMBINAÇÃO DE PREVISORES PARA PREVISÃO DE SÉRIES TEMPORAIS DE CARGA ELÉTRICA
Directory of Open Access Journals (Sweden)
Max Olinto Moreira
2012-03-01
Full Text Available A previsão da demanda de carga é uma tarefa fundamental para um bom funcionamento dos sistemas elétricos, pois vários processos de tomada de decisão, tais como planejamento, operação, análise de segurança e decisões de mercado, são altamente influenciados por este processo. Sabendo que o atendimento da demanda de carga é um processo estocástico, esta previsão se mostra importante para que uma empresa de distribuição promova um fornecimento de energia de forma segura, econômica e contínua. Nesta ótica, este trabalho propõe a elaboração de uma metodologia de previsão de carga à curto prazo, baseada na combinação de vários previsores distintos. Os resultados alcançados mostraram que a combinação dos previsores apresentou, na maioria dos casos analisados, resultados mais acurados quando comparados aos resultados obtidos por apenas uma componente de previsão individualmente. Neste modelo, a previsão da curva de demanda de carga baseia-se nas curvas de demanda de dias já conhecidos.
CFD validation experiments for hypersonic flows
Marvin, Joseph G.
1992-01-01
A roadmap for CFD code validation is introduced. The elements of the roadmap are consistent with air-breathing vehicle design requirements and related to the important flow path components: forebody, inlet, combustor, and nozzle. Building block and benchmark validation experiments are identified along with their test conditions and measurements. Based on an evaluation criteria, recommendations for an initial CFD validation data base are given and gaps identified where future experiments could provide new validation data.
Energy Technology Data Exchange (ETDEWEB)
Galindo G, I. F., E-mail: igalindo@iie.org.mx [Instituto de Investigaciones Electricas, Reforma No. 113, Col. Palmira, 62490 Cuernavaca, Morelos (Mexico)
2013-10-15
The scenarios simulation in nuclear power plants is usually carried out with system codes that are based on concentrated parameters networks. However situations exist in some components where the flow is predominantly 3-D, as they are the natural circulation, mixed and stratification phenomena. The simulation techniques of computational fluid dynamics (CFD) have the potential to simulate these flows numerically. The use of CFD simulations embraces many branches of the engineering and continues growing, however, in relation to its application with respect to the problems related with the safety in nuclear power plants, has a smaller development, although is accelerating quickly and is expected that in the future they play a more emphasized paper in the analyses. A main obstacle to be able to achieve a general acceptance of the CFD is that the simulations should have very complete validation studies, sometimes not available. In this article a general panorama of the state of the methods application CFD in nuclear power plants is presented and the problem associated to its routine application and acceptance, including the view point of the regulatory authorities. Application examples are revised in those that the CFD offers real benefits and are also presented two illustrative study cases of the application of CFD techniques. The case of a water recipient with a heat source in its interior, similar to spent fuel pool of a nuclear power plant is presented firstly; and later the case of the Boron dilution of a water volume that enters to a nuclear reactor is presented. We can conclude that the CFD technology represents a very important opportunity to improve the phenomena understanding with a strong component 3-D and to contribute in the uncertainty reduction. (Author)
Directory of Open Access Journals (Sweden)
Júlia Trevisan Martins
2013-01-01
Full Text Available OBJETIVO: Analisar o significado das cargas de trabalho para operacionais de limpeza de uma unidade de Emergência/Pronto Socorro e identificar as estratégias que eles utilizam como proteção as essas cargas. MÉTODOS: Estudo descritivo, exploratório qualitativo, com a participação de 12 operacionais de limpeza. A coleta de dados foi realizada por meio de entrevistas semiestruturadas e as falas submetidas à análise de conteúdo em suas etapas: leitura, determinação das unidades de registro e significações, codificação e classificação; tratamento e interpretação dos resultados obtidos. RESULTADOS: Emergiram três categorias: carga vivenciada no trabalho relacionada com a materialidade interna, carga vivenciada no trabalho relacionada com a materialidade externa e estratégias de enfrentamento utilizadas para amenizar e/ou prevenir as cargas no trabalho. CONCLUSÃO: Os profissionais conhecem parcialmente as cargas as quais estão expostos e enfrentam-nas individualmente.OBJECTIVE: To reveal the meaning of work operational loads on the operational cleaning Emergency Unit / Emergency and identify the strategies that they use as the protection these loads. METHOD: Descriptive, exploratory and qualitative, with 12 operational cleaning. Data collection was conducted through semi-structured interviews and statements submitted to content analysis in its phases: reading, register units and meanings, coding and classification; results treatment and interpreting. RESULTS: Three categories emerged: Work load related to internal materiality, work load related to external materiality, and coping strategies used to mitigate or prevent workloads. CONCLUSION: Professionals knew workloads partially and used self coping strategies.
The Role of CFD Simulation in Rocket Propulsion Support Activities
West, Jeff
2011-01-01
Outline of the presentation: CFD at NASA/MSFC (1) Flight Projects are the Customer -- No Science Experiments (2) Customer Support (3) Guiding Philosophy and Resource Allocation (4) Where is CFD at NASA/MSFC? Examples of the expanding Role of CFD at NASA/MSFC (1) Liquid Rocket Engine Applications : Evolution from Symmetric and Steady to 3D Unsteady (2)Launch Pad Debris Transport-> Launch Pad Induced Environments (a) STS and Launch Pad Geometry-steady (b) Moving Body Shuttle Launch Simulations (c) IOP and Acoustics Simulations (3)General Purpose CFD Applications (4) Turbomachinery Applications
International Nuclear Information System (INIS)
Tu, J.Y.
2004-01-01
A CFD and RTD Education Package was developed, in which lecture notes, tutorials and computer softwares for both CFD and RTD are included. A user-friendly web-based interface has been prepared to allow lecturers more effectively conducting their training courses or workshops, and to provide students or users more easily learning the CFD and RTD knowledge and practising computer softwares. This report gives an overview of the advances in development and use of CFD models and codes for industrial, particularly multiphase processing applications. Experimental needs for validation and improvement of CFD models and softwares are highlighted. Integration of advanced CFD modelling with radiotracer techniques as a complementary technology for future research and industrial applications is discussed. The features and examples of the developed CFD and RTD Education package are presented. (author)
Factores de riesgo en el bajo peso al nacer
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Guillermo Díaz Alonso
Full Text Available Se realizó un estudio retrospectivo de tipo caso control en el área del Policlínico Docente "Luis A. Turcios Lima" del municipio 10 de Octubre durante el período de 1990 a 1993, con el objetivo de identificar el comportamiento del bajo peso al nacer, establecer la existencia y la intensidad de esta entidad con los factores de riesgo seleccionados, e identificar el grado de influencia individual de dichos factores. La muestra quedó conformada por 92 recién nacidos de bajo peso y 468 con normopeso. Las variables estudiadas fueron la edad materna, la valoración ponderal, las complicaciones obstétricas, las enfermedades asociadas con la gestación, el hábito de fumar y el período intergenésico. Se aplicó el test chi-cuadrado, el odds- -ratio y el de riesgo atribuible en los nacimientos expuestos y en la población total. Todas las variables estuvieron asociadas significativamente con el bajo peso al nacer, y fueron identificadas como factores de riesgo con influencia marcada: la edad materna de 35 años o más, la amenaza de parto prematuro, la rotura prematura de membranas, la toxemia y la diabetes mellitus; con efecto moderado, el bajo peso materno, un período intergenésico menor de 1 año, la hipertensión arterial, el asma bronquial, el hábito de fumar, la sepsis urinaria, y con influencia ligera, la edad materna inferior a los 20 años.
International research progress of CFD application in analysis of nuclear power system
International Nuclear Information System (INIS)
Li Linsen; Wang Kan; Song Xiaoming
2009-01-01
This paper introduces the latest international research progress of CFD application in nuclear reactor system analysis. CFD method has been applied to a few 3-D single phase transient simulations, including flow field modeling of the reactor cores, assemblies, and vessel plenums. On the other hand, CFD method applied to reactor system still needs further validation and benchmarking, meanwhile,the application of CFD also needs to be studied, including the setup of the Best Practice Guidelines (BPG). Furthermore, CFD codes are used to couple with thermal-hydraulic system codes or neutronic codes. Eventually, in two phase field and turbulence modeling, CFD codes are still being developed. (authors)
Validating CFD Predictions of Pharmaceutical Aerosol Deposition with In Vivo Data.
Tian, Geng; Hindle, Michael; Lee, Sau; Longest, P Worth
2015-10-01
CFD provides a powerful approach to evaluate the deposition of pharmaceutical aerosols; however, previous studies have not compared CFD results of deposition throughout the lungs with in vivo data. The in vivo datasets selected for comparison with CFD predictions included fast and slow clearance of monodisperse aerosols as well as 2D gamma scintigraphy measurements for a dry powder inhaler (DPI) and softmist inhaler (SMI). The CFD model included the inhaler, a characteristic model of the mouth-throat (MT) and upper tracheobronchial (TB) airways, stochastic individual pathways (SIPs) representing the remaining TB region, and recent CFD-based correlations to predict pharmaceutical aerosol deposition in the alveolar airways. For the monodisperse aerosol, CFD predictions of total lung deposition agreed with in vivo data providing a percent relative error of 6% averaged across aerosol sizes of 1-7 μm. With the DPI and SMI, deposition was evaluated in the MT, central airways (bifurcations B1-B7), and intermediate plus peripheral airways (B8 through alveoli). Across these regions, CFD predictions produced an average relative error <10% for each inhaler. CFD simulations with the SIP modeling approach were shown to accurately predict regional deposition throughout the lungs for multiple aerosol types and different in vivo assessment methods.
Preliminary CFD Analysis for HVAC System Design of a Containment Building
Energy Technology Data Exchange (ETDEWEB)
Son, Sung Man; Choi, Choengryul [ELSOLTEC, Yongin (Korea, Republic of); Choo, Jae Ho; Hong, Moonpyo; Kim, Hyungseok [KEPCO Engineering and Construction, Gimcheon (Korea, Republic of)
2016-10-15
HVAC (Heating, Ventilation, Air Conditioning) system has been mainly designed based on overall heat balance and averaging concepts, which is simple and useful for designing overall system. However, such a method has the disadvantage that cannot predict the local flow and temperature distributions in a containment building. In this study, a CFD (Computational Fluid Dynamics) preliminary analysis is carried out to obtain detailed flow and temperature distributions in a containment building and to ensure that such information can be obtained via CFD analysis. This approach can be useful for hydrogen analysis in an accident related to hydrogen released into a containment building. In this study, CFD preliminary analysis has been performed to obtain the detailed information of the reactor containment building by using the CFD analysis techniques and to ensure that such information can be obtained via CFD analysis. We confirmed that CFD analysis can offer enough detailed information about flow patterns and temperature field and that CFD technique is a useful tool for HVAC design of nuclear power plants.
Actualización en el manejo del colesterol hdl bajo
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Rigotti R. Attilio, Dr.
2012-11-01
Full Text Available Los niveles plasmáticos bajos de colesterol transportado en las lipoproteínas de alta densidad (HDL constituyen un elemento independiente de riesgo cardiovascular ateroesclerótico. Algunos protocolos clínicos enfocados en el manejo farmacológico de los niveles bajos de colesterol HDL en pacientes de alto riesgo cardiovascular han mostrado resultados favorables. Por otro lado, existen nuevas formulaciones de la niacina, el agente farmacológico disponible más efectivo para el manejo del colesterol HDL bajo, y se están desarrollando nuevos fármacos más potentes para aumentar los niveles plasmáticos de colesterol HDL. En el futuro, nuevos medicamentos que modulen el metabolismo de HDL y demuestren beneficio sobre el control del riesgo cardiovascular ateroesclerótico, podrían mejorar aún más el manejo actual de esta condición patológica que se basa esencialmente en el uso de estatinas.
López Bula, Pedro Javier
2011-01-01
El presente trabajo, analiza las propiedades viscoelasticas de diferentes materiales asfalticos después de ser sometidos a cargas permanentes y a diferente temperatura -- Estas cargas simulan las que eventualmente se pueden presentar en la aplicacion y fabricación de productos asfalticos ampliamente utilizados en el sector de la construcción -- Para este estudio se utilizó asfalto crudo y modificado con diferentes polímeros: Cera de polietileno (CERA), caucho molido de llanta (CR), copolimero...
International Nuclear Information System (INIS)
2008-01-01
Computational Fluid Dynamics (CFD) is to an increasing extent being adopted in nuclear reactor safety analyses as a tool that enables specific safety relevant phenomena occurring in the reactor coolant system to be better described. The Committee on the Safety of Nuclear Installations (CSNI), which is responsible for the activities of the OECD Nuclear Energy Agency that support advancing the technical base of the safety of nuclear installations, has in recent years conducted an important activity in the CFD area. This activity has been carried out within the scope of the CSNI working group on the analysis and management of accidents (GAMA), and has mainly focused on the formulation of user guidelines and on the assessment and verification of CFD codes. It is in this GAMA framework that a first workshop CFD4NRS was organized and held in Garching, Germany in 2006. Following the CFD4NRS workshop, this XCFD4NRS Workshop was intended to extend the forum created for numerical analysts and experimentalists to exchange information in the field of Nuclear Reactor Safety (NRS) related activities relevant to Computational Fluid Dynamics (CFD) validation, but this time with more emphasis placed on new experimental techniques and two-phase CFD applications. The purpose of the workshop was to provide a forum for numerical analysts and experimentalists to exchange information in the field of NRS-related activities relevant to CFD validation, with the objective of providing input to GAMA CFD experts to create a practical, state-of-the-art, web-based assessment matrix on the use of CFD for NRS applications. The scope of XCFD4NRS includes: - Single-phase and two-phase CFD simulations with an emphasis on validation in areas such as: boiling flows, free-surface flows, direct contact condensation and turbulent mixing. These applications should relate to NRS-relevant issues such as: pressurized thermal shocks, critical heat flux, pool heat exchangers, boron dilution, hydrogen
Assessment of computational fluid dynamics (CFD) for nuclear reactor safety problems
International Nuclear Information System (INIS)
Smith, B. L.; Andreani, M.; Bieder, U.; Bestion, D.; Ducros, F.; Graffard, E.; Heitsch, M.; Scheuerer, M.; Henriksson, M.; Hoehne, T.; Rohde, U.; Lucas, D.; Komen, E.; Houkema, M.; Mahaffy, J.; Moretti, F.; Morii, T.; Muehlbauer, P.; Song, C.H.; Zigh, G.; Menter, F.; Watanabe, T.
2008-01-01
The basic objective of the present work was to provide documented evidence of the need to perform CFD simulations in Nuclear Reactor Safety (NRS), concentrating on single-phase applications, and to assess the competence of the present generation of CFD codes to perform these simulations reliably. The fulfilling of this objective involves multiple tasks, summarized as: to provide a classification of NRS problems requiring CFD analysis, to identify and catalogue existing CFD assessment bases, to identify shortcomings in CFD approaches, to put into place a means for extending the CFD assessment database, with an emphasis on NRS applications. The resulting document is presented here. After some introductory remarks, chapter 3 lists twenty-two NRS issues for which it is considered that the application of CFD would bring real benefits in terms of better predictive capability. This classification is followed by a short description of the safety issue, a state-of-the-art summary of what has been attempted, and what is still needed to be done to improve reliability. Chapter 4 details the assessment bases that have already been established in both the nuclear and non-nuclear domains, and discusses the usefulness and relevance of the work to NRS applications, where appropriate. This information is augmented in Chapter 5 by descriptions of the existing CFD assessment bases that have been established around specific, NRS problems. Typical examples are experiments devoted to the boron dilution issue, pressurised thermal shock, and thermal fatigue in pipes. Chapter 6 is devoted to identifying the technology gaps which need to be closed to make CFD a more trustworthy analytical tool. Some deficiencies identified are lack of a Phenomenon Identification and Ranking Table (PIRT), limitations in the range of application of turbulence models, coupling of CFD with neutronics and system codes, and computer power limitations. Most CFD codes currently being used have their own, custom
CFD analysis on heat transfer in low Prandtl number fluid flows
Energy Technology Data Exchange (ETDEWEB)
Borgohain, A.; Maheshwari, N.K.; Vijayan, P.K.; Sinha, R.K., E-mail: bananta@barc.gov.in [Bhabha Atomic Research Centre, Reactor Engineering Div., Trombay, Mumbai (India)
2011-07-01
Use of Computational Fluid Dynamics (CFD) code is helpful for designing liquid metal cooled nuclear reactor systems. Before using any CFD code proper evaluation of the code is essential for simulation of heat transfer in liquid metal flow. In this paper, a review of the literature on the correlations for liquid metal heat transfer is carried out and a comparison with experimental results is performed. CFD analysis is carried out using PHOENICS-3.6 code on heat transfer in molten Lead Bismuth Eutectic (LBE) flowing through tube. Turbulent flow analyses are carried out for the evaluation of the CFD code. The CFD results are compared with the available correlations. Assessment of various turbulence models and correlations for turbulent Prandtl number in the tube geometry are carried out. From the analysis it is found that, the CFD prediction can be improved with modified turbulent Prandtl number in the turbulence models. (author)
An Integrated Lumped Parameter-CFD approach for off-design ejector performance evaluation
International Nuclear Information System (INIS)
Besagni, Giorgio; Mereu, Riccardo; Chiesa, Paolo; Inzoli, Fabio
2015-01-01
Highlights: • We validate a CFD approach for a convergent nozzle ejector using global and local measurement. • We evaluate seven RANS turbulence models for convergent nozzle ejector. • We introduce a lumped parameter model for on-design and off-design ejector performance evaluation. • We analyze the relationship between local flow behavior and lumped parameters of the model. • We discuss how to improve predicting capabilities of the model by variable parameters calibrated on CFD simulations. - Abstract: This paper presents an Integrated Lumped Parameter Model-Computational Fluid-Dynamics approach for off-design ejector performance evaluation. The purpose of this approach is to evaluate the entrainment ratio, for a fixed geometry, in both on-design and off-design operating conditions. The proposed model is based on a Lumped Parameter Model (LPM) with variable ejector component efficiencies provided by CFD simulations. The CFD results are used for developing maps for ejector component efficiencies in a broad range of operating conditions. The ejector component efficiency maps couple the CFD and the LPM techniques for building an Integrated LPM-CFD approach. The proposed approach is demonstrated for a convergent nozzle ejector and the paper is structured in four parts. At first, the CFD approach is validated by global and local data and seven Reynolds Averaged Navier Stokes (RANS) turbulence models are compared: the k–ω SST showed good performance and was selected for the rest of the analysis. At second, a Lumped Parameter Model (LPM) for subsonic ejector is developed and the ejector component efficiencies have been defined. At third, the CFD approach is used to investigate the flow field, to analyze its influence on ejector component efficiencies and to propose efficiency correlations and maps linking ejector component efficiencies and local flow quantities. In the last part, the efficiency maps are embedded into the lumped parameter model, thus creating
Carga de trabalho de enfermagem em transplante de células-tronco hematopoiéticas: estudo de coorte
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Juliana Bastoni da Silva
2015-12-01
Full Text Available RESUMO Objetivo Mensurar a carga de trabalho de enfermagem requerida por pacientes submetidos ao transplante de células-tronco hematopoiéticas (TCTH, autólogo e alogênico e analisar as atividades do Nursing Activities Score (NAS executadas pela equipe de enfermagem durante a internação para o TCTH. Método Coorte prospectiva realizada de janeiro/2013 a abril/2014 com 62 pacientes internados na unidade de TCTH de um hospital universitário de Campinas/SP, Brasil. Mediu-se a carga de trabalho por meio do NAS e analisaram-se os dados utilizando os testes Qui-quadrado ou Exato de Fisher, Mann-Whitney e o coeficiente de correlação de Spearman; considerou-se nível de significância de 5%. Resultados A média da carga de trabalho de enfermagem foi de 67,3% (DP 8,2 em pacientes de TCTH autólogo e de 72,4% (DP 13,0 no TCTH alogênico (p=0,1380. O item Monitorização e controles apontou, em mais de 50% das observações, que os pacientes demandaram intensificação deste cuidado, exigindo duas horas ou mais em algum turno de trabalho por motivos de segurança, gravidade ou terapia. Conclusão A carga de trabalho de enfermagem e os itens do NAS mais pontuados refletem a magnitude, complexidade e especificidade dos cuidados demandados pelos pacientes submetidos ao TCTH.
Guyonvarch, Estelle; Ramin, Elham; Kulahci, Murat; Plósz, Benedek Gy
2015-10-15
The present study aims at using statistically designed computational fluid dynamics (CFD) simulations as numerical experiments for the identification of one-dimensional (1-D) advection-dispersion models - computationally light tools, used e.g., as sub-models in systems analysis. The objective is to develop a new 1-D framework, referred to as interpreted CFD (iCFD) models, in which statistical meta-models are used to calculate the pseudo-dispersion coefficient (D) as a function of design and flow boundary conditions. The method - presented in a straightforward and transparent way - is illustrated using the example of a circular secondary settling tank (SST). First, the significant design and flow factors are screened out by applying the statistical method of two-level fractional factorial design of experiments. Second, based on the number of significant factors identified through the factor screening study and system understanding, 50 different sets of design and flow conditions are selected using Latin Hypercube Sampling (LHS). The boundary condition sets are imposed on a 2-D axi-symmetrical CFD simulation model of the SST. In the framework, to degenerate the 2-D model structure, CFD model outputs are approximated by the 1-D model through the calibration of three different model structures for D. Correlation equations for the D parameter then are identified as a function of the selected design and flow boundary conditions (meta-models), and their accuracy is evaluated against D values estimated in each numerical experiment. The evaluation and validation of the iCFD model structure is carried out using scenario simulation results obtained with parameters sampled from the corners of the LHS experimental region. For the studied SST, additional iCFD model development was carried out in terms of (i) assessing different density current sub-models; (ii) implementation of a combined flocculation, hindered, transient and compression settling velocity function; and (iii
Energy Technology Data Exchange (ETDEWEB)
Scharler, R. [Bios Bioenergiesystem GmbH, Graz (Austria); Obernberger, I. [Technische Univ. Eindhoven (Netherlands). Thermochemische Biomassekonversion; Weissinger, A. [Oesterreichische Kraft und Waerme aus Biomasse GmbH (KWB), St. Margarethen/Raab (Austria). Bereich Forschung und Entwicklung; Schmidt, W. [Oesterreichische Kraft und Waerme aus Biomasse GmbH (KWB), St. Margarethen/Raab (Austria). Bereich Produktentwicklung, Umwelt- und Informationsmanagement
2005-07-01
Despite the complexity of solid biomass combustion, the Bios Bioenergiesysteme GmbH, Graz, Austria, has successfully developed and optimised several biomass furnaces in the range of 500 kW to 30 MW based on CFD (Computational Fluid Dynamics). A project carried out in co-operation with the KWB Kraft und Waerme aus Biomasse GmbH, St. Margarethen, Austria, demonstrates the application of CFD for the efficient and improved design of small-scale furnaces for solid biofuels like pellets and wood chips as basis for a series production. (orig.)
Ordenamiento y solución de flujos de carga en sistemas radiales
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Lucio Florez C.
1986-01-01
Full Text Available En estudios de planeación y operación de sistemas de distribución, es necesario efectuar gran cantidad de estudios de reparto de carga, corlo circuito y análisis de contingencias entre otros, de aquí que es muy importante para el ahorro de tiempo y memoria de cómputo, como también para la confiablidad de la solución el empleo de algoritmos adecuados. Una parte fundamental de estos algoritmos es la relacionada con el ordenamiento, factorización y solución de ecuaciones lineales. En este trabajo se plantea un algoritmo sencillo de ordenamiento, factorización y solución de ecuaciones lineales, aprovechando la estructura de los sistemas radiales (los cuales son frecuentes en distribución, lo que conlleva a una reducción en tiempo y memoria de cómputo respecto a los algoritmos tradicionalmente utilizados, teniendo una aplicación inmediata en reparto de carga y corto circuito de sistemas radiales.
The development and application of CFD technology in mechanical engineering
Wei, Yufeng
2017-12-01
Computational Fluid Dynamics (CFD) is an analysis of the physical phenomena involved in fluid flow and heat conduction by computer numerical calculation and graphical display. The numerical method simulates the complexity of the physical problem and the precision of the numerical solution, which is directly related to the hardware speed of the computer and the hardware such as memory. With the continuous improvement of computer performance and CFD technology, it has been widely applied to the field of water conservancy engineering, environmental engineering and industrial engineering. This paper summarizes the development process of CFD, the theoretical basis, the governing equations of fluid mechanics, and introduces the various methods of numerical calculation and the related development of CFD technology. Finally, CFD technology in the mechanical engineering related applications are summarized. It is hoped that this review will help researchers in the field of mechanical engineering.
Best Practices for Reduction of Uncertainty in CFD Results
Mendenhall, Michael R.; Childs, Robert E.; Morrison, Joseph H.
2003-01-01
This paper describes a proposed best-practices system that will present expert knowledge in the use of CFD. The best-practices system will include specific guidelines to assist the user in problem definition, input preparation, grid generation, code selection, parameter specification, and results interpretation. The goal of the system is to assist all CFD users in obtaining high quality CFD solutions with reduced uncertainty and at lower cost for a wide range of flow problems. The best-practices system will be implemented as a software product which includes an expert system made up of knowledge databases of expert information with specific guidelines for individual codes and algorithms. The process of acquiring expert knowledge is discussed, and help from the CFD community is solicited. Benefits and challenges associated with this project are examined.
El crecimiento y desarrollo ante la prematuridad y el bajo peso al nacer
Directory of Open Access Journals (Sweden)
Christine Baccarat de Godoy Martins
2015-09-01
Full Text Available Objetivo: Realizar una revisión bibliográfica sobre el crecimiento y desarrollo de prematuros y/o de bajo peso al nacer. Metodología: Se utilizaron las bases de datos lilacs, medline y scielo. Se encontraron 64 trabajos: 10 publicados en 2005, 10 en 2006, 12 en 2007, 16 en 2008, 8 en 2009 y 8 en 2010. Las publicaciones halladas pertenecían a las áreas de medicina (59,4%, nutrición (7,8%, enfermería (7,8%, salud pública (7,8%, psicología (6,2%, epidemiología (4,7%, fisiología (3,1% y fonoaudiología (3,1%. Resultados:Los textos encontrados permitieron la organización del conocimiento producido según las siguientes categorías de análisis: Factores asociados al bajo peso en el nacimiento/prematuridad; Repercusiones del bajo peso en el nacimiento/prematuridad para el crecimiento y desarrollo y medidas de prevención; y Supervivencia de los recién nacidos prematuros o de bajo peso. Conclusión: Los niños nacidos prematuramente y de bajo peso generalmente presentan déficit de desarrollo. Un acompañamiento postnatal centrado en el crecimiento y desarrollo es fundamental.
Rivas Trujillo, Edwin
2011-01-01
Un cambiador de tomas en carga (OLTC, en inglés” On-Load Tap Changer”, o CTC en español) o regulador es la única parte con movimiento en un transformador. Su función es realizar la operación de cambio de una toma del arrollamiento de regulación a otra, permitiendo regular la tensión de salida del transformador a los niveles requeridos sin la interrupción de la corriente de carga. La valoración del estado electro-mecánico (buen estado o con avería) de un cambiador de tomas en carga es importan...
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Jimena Obregón Iturra
2008-07-01
Full Text Available En este artículo nos proponemos cuestionar la diferenciación binaria entre indios amigos e indios enemigos, ampliamente difundida durante el siglo XVII para calificar a los distintos grupos araucano-mapuches del sur de Chile. Restringiendo el análisis al funcionamiento de esta categorización dual bajo el gobierno del Marqués de Baides, mostramos cómo el primer Parlamento de Quillín enuncia y consagra la partición entre los “enemigos” ausentes del parlamento y los “amigos” que han dado las paces, haciendo desaparecer los términos medios. Paralelamente, planteamos que retomar de manera acrítica categorías heredadas del pasado colonial, que además conllevan tal carga ideológica, dificulta la comprensión de una compleja realidad fronteriza que dista mucho de ser dicotómica. Finalmente, recalcamos los arduos problemas plan- teados por la polémica figura de Carl Schmitt que, a lo largo del siglo XX, dejó su engorrosa impronta en la conceptualización amigos/enemigos.
Directory of Open Access Journals (Sweden)
Jorge Cuadrado-Reyes
2012-01-01
Full Text Available El propósito de esta investigación es estudiar la aplicabilidad de la Percepción Subjetiva del Esfuerzo (PSE desde una doble perspectiva, en primer lugar, como apoyo al seguimiento de la cuantificación de la carga administrada en los entrenamientos en deportes colectivos, y en segundo lugar, como herramienta ad hoc para el control diario del entrenamiento sobre lo planificado por el cuerpo técnico. La frecuencia cardiaca de reserva (FCR ha sido utilizada para controlar la carga interna de cada sesión. Trece jugadores pertenecientes a un equipo de balonmano de División de Honor española participaron en la investigación llevada a cabo a lo largo de una temporada. Los resultados mostraron que la PSE es un buen indicador de la carga de entrenamiento, consiguiéndose además un procedimiento válido para comparar valores de la carga planificada por el equipo técnico (PSEp con respecto a los valores reales de entrenamiento (PSEg (rxy= .792; p < .01. Se puede concluir que la PSE junto a la FCR (rxy= .839; p < .01 son buenos marcadores para el control de la carga de entrenamiento, no invasivos, y permiten monitorizar los estados de forma de los jugadores a lo largo de la temporada.
Estudio ergonómico: Levantamiento manual de Cargas
Cruz Solis, Carolina
2014-01-01
El presente trabajo se ha realizado en BODEGAS RIERA S.A dedicada a la facturación de botellas y lotes de vinos La introducción de nuevas tecnologías para el desarrimado de botellas en la empresa, ha dado lugar a la realización de una evaluación específica de riesgos laborales en los puestos de trabajo de la sección de la LÍNEA DE ESPECIALES. Se ha identificado un posible riesgo por factores ergonómicos en la manipulación manual de cargas, por lo que se ha planificado esta valoración espec...
ABEJAS VISITANTES DE Mimosa pigra L. (MIMOSACEAE:COMPORTAMIENTO DE PECOREO Y CARGAS POLÍNICAS
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CLARA ISABEL AGUILAR SIERRA
2009-01-01
Full Text Available RESUMEN Se estudiaron las cargas polínicas de 13 taxones de abejas capturadas visitando a Mimosa pigra en la zona de influencia del Embalse Porce II (Antioquia, Colombia. De los 21 tipos polínicos encontrados, M. pigra presenta el mayor porcentaje acumulado de colecta; Mimosa pudica, Piper aduncum, Solanum diversifolium, Warszewiczia coccinea y Psidium guajava, en su orden, se pueden considerar fuentes alternativas de polen, para varias de las especies de abejas cuyas cargas polínicas fueron analizadas. Dentro de las especies de abejas capturadas visitando a M. pigra se pueden diferenciar varios grupos según el tipo y abundancia relativa de los tipos polínicos encontrados en sus cargas. Uno de ellos, incluye a siete especies de abejas con más del 85% de granos de polen de M. pigra; otro, con cuatro especies de abejas que colectaron más del 94,5% del polen en M. pigra y M. pudica. Adicionalmente, se encontraron especies como Trigona dorsalis con cargas de M. pigra (59,4%, de S. diversifolium (37,8% y especies de abejas como Lasioglossum sp. 113, en cuyas cargas polínicas predominan los granos de polen de P. aduncum (61,8% y de W.coccinea (36,4%, en contraste con los de M. pigra (1,3%. En cuanto a la riqueza de tipos polínicos colectados por las abejas sobresalen Trigona muzoensis (12 tipos polínicos y T. dorsalis (10 tipos, lo cual refleja nichos tróficos más amplios para estas especies y deja duda sobre su constancia floral o hábitos de limpieza. Palabras clave: Mimosa pigra, cargas polínicas, tipos polínicos, abejas, polinización. ABSTRACT We studied the pollen loads of 13 taxa of wild bees visiting the flowers of Mimosa pigra on the influence zone of the Dam Project Porce II (Antioquia, Colombia. Out of 21 different pollen types, M. pigra represents the higuest percentage; Mimosa pudica, Piper aduncum, Solanum diversifolium, Warszewiczia coccinea and Psidium guajava, in that order, were also abundant, and are alternative
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JUAN PABLO RIVERA
2009-07-01
Full Text Available El crecimiento de los sistemas de potencia y las condiciones de mercado dadas por los esquemas desregulados han evidenciado las limitantes técnicas y de operación que los sistemas eléctricos de potencia SEP tienen para abastecer la demanda bajo estrictas condiciones de seguridad, calidad de potencia y confiabilidad. Un controlador unificado de flujos de potencia UPFC (unified power flow controller es uno de los dispositivos de la tecnología FACTS (Flexible AC Transmission Systems que ofrece mayor versatilidad en términos de interacción con las variables de operación y control de un SEP y puede ser una solución óptima a las necesidades adicionales de control en un SEP moderno. Este trabajo presenta una formulación matemática y conceptual para la inclusión de un dispositivo UPFC en el análisis de flujos de carga en un SEP y una metodología para su inclusión en un software de flujos de carga en estado estable. Para validar la eficiencia de los modelos y métodos propuestos, se selecciona un sistema de potencia de prueba adecuado para ver los efectos esperados de la inclusión del UPFC en el sistema.O crescimento dos sistemas de potência e as condições de mercado dadas pelos esquemas desregulados evidenciaram as limitantes técnicas e de operação que os sistemas elétricos de potência SET têm para abastecer a demanda sob estritas condições de segurança, qualidade de potência e confiabilidade. Um controlador unificado de fluxos de potência UPFC (unified power flow controller é um dos dispositivos da tecnologia FACTS (flexible AC transmission systems que oferece maior versatilidade em termos de interação com as variáveis de operação e controle de um SET e pode ser uma solução ótima às necessidades adicionais de controle em um SET moderno. Este trabalho apresenta uma formulação matemática e conceptual para a inclusão de um dispositivo UPFC na análise de fluxos de carga em um SET e uma metodologia para sua
Diagnóstico de averías de un cambiador de tomas en carga mediante redes neuronales
Piñas García, Miguel Ángel
2010-01-01
Un cambiador de tomas en carga por sus siglas en español CTC u OLTC por sus siglas en inglés (“On-Load Tap Changer”) es la única parte con movimiento en un transformador. Su Misión es realizar la operación de cambio de una toma a otra del devanado de regulación, modificando el número de espiras en uno de los devanados, en respuesta a un cambio de tensión en la red debido a variaciones en la carga. De acuerdo a una encuesta internacional realizada por el CIGRE el 40% de los fallos del transfor...
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Francisco Javier Carmona-Monge
2013-04-01
Full Text Available Se objetivó valorizar la carga de trabajo al ingreso y al alta en tres grupos de pacientes (síndrome coronario agudo, insuficiencia respiratoria aguda y sepsis en terapia intensiva. Estudio descriptivo, prospectivo, de 27 meses, incluyéndose 563 pacientes, valorando carga de trabajo según Nursing Activities Score. Existieron diferencias significativas en la carga de trabajo al ingreso y en el alta entre los grupos de pacientes, siendo superior en ambos momentos la de pacientes con insuficiencia respiratoria aguda y sepsis frente a pacientes coronarios. Durante los siete primeros días de estancia se mantuvo esta diferencia, desapareciendo a partir del octavo día, equilibrándose la carga de trabajo para los tres grupos. Para conseguir una adecuada dotación de personal es fundamental contar con instrumentos para medir las necesidades de cuidados y conocer la carga de trabajo de los distintos grupos de enfermos que ingresan con mayor frecuencia en las unidades de terapia intensiva.O objetivo deste estudo foi avaliar a carga de trabalho na admissão e alta dos pacientes de três grupos (síndrome coronária aguda, insuficiência respiratória aguda e sepsis em cuidados intensivos. Trata-se de estudo prospectivo, descritivo, que decorreu durante 27 meses, incluindo 563 pacientes. Para a avaliação da carga de trabalho utilizou-se a escala Nursing Activities Score. A partir dos resultados do estudo parecem existir diferenças significativas na carga de trabalho no dia da admissão e alta entre os grupos de pacientes, sendo a carga maior em ambos os tempos a dos pacientes com insuficiência respiratória aguda e sepsis. Durante os primeiros sete dias de internamento essa diferença manteve-se, desaparecendo no oitavo dia, o que equilibrou a carga de trabalho para os três grupos. Conclui-se que para se conseguir os recursos adequados é essencial dispor de instrumentos para medir as necessidades de cuidados e conhecer a carga de trabalho dos
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Oscarlina Lucia dos Santos Weber
2005-12-01
Full Text Available Os solos tropicais altamente intemperizados apresentam teor significativo de colóides com carga elétrica variável. Entretanto, são poucas as referências em relação à quantificação destas cargas, principalmente em solos ácricos, que representam o extremo na escala de intemperismo. Neste estudo, foram determinadas as cargas permanentes e as variáveis de dois Latossolos Vermelhos acriférricos, um Latossolo Amarelo ácrico e um Latossolo Amarelo acriférrico, que foram comparados a um Nitossolo Vermelho eutroférrico, com carga predominantemente permanente. As amostras foram investigadas pelo método da adsorção do íon césio (Cs+, que mede a carga estrutural permanente (sigmao e baseia-se na preferência do Cs+ sobre o Li+ na superfície da siloxana de grupos de superfície ionizáveis de menor seletividade ao íon Cs+. A carga variável representou mais que 50 % da carga total dos solos estudados. Dois dos quatro Latossolos com propriedades ácricas exibiram quantidade significativa de carga permanente, provavelmente em razão da presença de vermiculita com hidróxi entrecamadas e clorita. A quantidade de carga permanente apresentada pelo Nitossolo foi até cinco vezes maior se comparada à dos Latossolos, o que pode ser atribuído à diferença na constituição mineralógica. O método da adsorção de Cs foi capaz de identificar teores significativos de carga permanente estrutural, mesmo em solos com baixo teor de minerais 2:1.Highly weathered tropical soils present high amount of colloids with variable electrical charge. However, there are few references related to the quantification of such charges, mainly in soils with acric attributes, which represent one of the extremes in the weathering scale. In this study permanent and variable charges were determined in four Oxisols and compared to an Alfisol with predominantly permanent charge. Samples were investigated using the Cs+ adsorption method, which measures the structural
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Idalberto Tamayo Ávila
2015-01-01
Full Text Available En este trabajo se obtuvieron resultados que evidencian la formación de carga de espacio en polietileno de baja densidad, LDPE, causados por la aborción de humedad. Se demostró que mientras mayor es el tiempo de exposición de las muestras a la atmósfera húmeda de vapor de agua, crece la carga acumulada en las interfaces y en el volumen del polietileno. También se pudo observar que la humedad facilita el proceso de conducción de paquetes de carga a través de los films de polietileno, empleando menos tiempo en muestras humedecidas que en las que no se humedecieron. La humedad absorbida por el LDPE contribuye a que existan mayor cantidad de centros de atrapamiento para la carga inyectada desde los electrodos y al aporte de carga volumétrica por ionización debido al efecto de campos eléctricos elevados.
CFD simulations of the MEXICO rotor
DEFF Research Database (Denmark)
Bechmann, Andreas; Sørensen, Niels N.; Zahle, Frederik
2011-01-01
The wake behind a wind turbine model is investigated using Computational Fluid Dynamics (CFD), and results are compared with measurements. The turbine investigated is the three‐bladed test rotor (D = 4.5 m) used in the Model Experiments in Controlled Conditions (MEXICO) wind tunnel experiment....... During the MEXICO experiment, particle image velocimetry measurements of the induction upstream and downstream of the rotor were performed for different operating conditions, giving a unique dataset to verify theoretical models and CFD models. The present paper first describes the efforts in reproducing...
FORMAS DE LEITO E TRANSPORTE DE CARGA DE FUNDO DO ALTO RIO PARANÁ
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Débora Pinto Martins
2005-12-01
Full Text Available O presente trabalho estima o transporte de carga de fundo no alto rio Paraná em Porto São José, PR (22º45’52”S e 53°10’34”W, num trecho de aproximadamente 2 km a jusante da Usina Hidrelétrica Engenheiro Sérgio Motta (Porto Primavera, onde o rio Paraná apresenta canal único com largura média de 1.200m e vazão média anual é de 8.912 m³/s. O cálculo da carga de fundo do canal foi baseado na determinação do tamanho das formas de leito e de sua velocidade de deslocamento linear, obtidos a partir de sucessivos levantamentos batimétricos. Foram realizadas três campanhas de levantamentos ecobatimétricos em diferentes momentos do ciclo hidrológico do rio, sendo cada campanha constituída por dois levantamentos separados em intervalos de 16 a 20 dias. O cálculo da carga de fundo baseou-se equação: Cf = (1-pH k Ud onde p é a porosidade (adimensional, H a altura média das formas de leito (m, k o coeficiente morfométrico das formas de leito (adimensional e Ud a velocidade de deslocamento das formas de leito (m/dia. As dunas são as formas de leito predominantes neste trecho do rio Paraná, com comprimento entre 50 e 100 m (média de 70,68 m e altura de 0,80 a 2,20 m (média de 1,30 m. A velocidade média de deslocamento linear das formas de fundo foi de 56,8 m/mês, para o período de maior vazão; e 45,0 m/mês para o período de menor vazão. O transporte médio de carga e fundo no rio Paraná foi estimado em 2.820,6 ton/dia, o que corresponde a 1.029.300 ton/ano. Comparando com dados anteriores, os autores sugerem que o transporte hidrossedimentar de fundo no trecho de canal estudado está sofrendo interferência da barragem de Porto Primavera.
Campo eletromagnético de uma carga em queda livre num campo gravitacional uniforme
Goto, Mario
2010-01-01
As transformações de Rindler são usadas para obter o campo eletromagnético de uma carga em queda livre num campo gravitacional uniforme. Electromagnetic field of free falling charge in an uniform gravitational field is obtained using Rindler transformations.
Aulas-laboratorios de bajo costo, usando TIC
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Silvia E. Calderón
2015-01-01
Full Text Available En este trabajo se presentan los resultados de una propuesta educativa orientada a promover el desarrollo de un pensamiento critico y un mayor interes por las ciencias experimentales. Con este fin desarrollamos propuestas de proyectos educativos susceptibles de ser destinadas a las aulas y laboratorios de las escuelas secundarias y primeros anos de la universidad, que resaltan los aspectos metodologicos de las ciencias. Aqui, realizamos una compilacion de varios proyectos, que ilustran formas de incorporar las tecnologias de la informacion y la comunicacion (TIC en diversos experimentos de ciencias, muchos de ellos publicados individualmente anteriormente, y que en conjunto se pueden utilizar para implementar un aula-laboratorio de bajo costo. Con TIC hacemos referencia a la convergencia de computadoras, sistemas audiovisuales, Internet, telefonia, y diversos equipos que se integran con algunos de ellos. Los proyectos intentan integrar areas como fisica, matematica, quimica, informatica, arte, etc. y apuntan a que los estudiantes puedan responder a las preguntas: .Como sabemos esto?, .Por que creemos en aquello? Preguntas que ilustran la naturaleza del pensamiento cientifico. Nuestra contribucion mas significativa es haber desarrollado ≪aulas-laboratorios≫ de muy bajo costo, usando TIC. Con el advenimiento de programas como ≪Una Laptop por Nino≫ que se estan implementando en varios paises de Latinoamerica, resulta oportuno utilizar este recurso como base para generar laboratorios de bajo costo, que creemos pueden ser una herramienta util para mejorar el aprendizaje de las ciencias, incentivar vocaciones y contribuir a desarrollar un pensamiento critico, a la par de desarrollar habilidades con el uso de las TIC que pueden ser de utilidad en diversos ambitos academicos y laborales.
The extensive international use of commercial computational fluid dynamics (CFD) codes
International Nuclear Information System (INIS)
Hartmut Wider
2005-01-01
What are the main reasons for the extensive international success of commercial CFD codes? This is due to their ability to calculate the fine structures of the investigated processes due to their versatility, their numerical stability and that they can guarantee the proper solution in most cases. This was made possible by the constantly increasing computer power at an ever more affordable prize. Furthermore it is much more efficient to have researchers use a CFD code rather than to develop a similar code system due to the time consuming nature of this activity and the high probability of hidden coding errors. The centralized development and upgrading makes these reliable CFD codes possible and affordable. However, the CFD companies' developments are naturally concentrated on the most profitable areas, and thus, if one works in a 'non-priority' field one cannot use them. Moreover, the prize of renting CFD codes, applications to complex systems such as whole nuclear reactors and the need to teach students gives the development of self-made codes still plenty of room. But CFD codes can model detailed aspects of large systems and subroutines generated by users can be added. Since there are only a few heavily used CFD codes such as FLUENT, STAR-CD, ANSYS CFX, these are used in many countries. Also international training courses are given and the news bulletins of these codes help to spread the news on further developments. A larger number of international codes would increase the competition but would at the same time make it harder to select the most appropriate CFD code for a given problem. Examples will be presented of uses of CFD codes as more detailed system codes for the decay heat removal from reactors, the application to aerosol physics and the application to heavy metal fluids using different turbulence models. (author)
Computational Fluid Dynamics (CFD) Technology Programme 1995- 1999
Energy Technology Data Exchange (ETDEWEB)
Haekkinen, R.J.; Hirsch, C.; Krause, E.; Kytoemaa, H.K. [eds.
1997-12-31
The report is a mid-term evaluation of the Computational Fluid Dynamics (CFD) Technology Programme started by Technology Development Centre Finland (TEKES) in 1995 as a five-year initiative to be concluded in 1999. The main goal of the programme is to increase the know-how and application of CFD in Finnish industry, to coordinate and thus provide a better basis for co-operation between national CFD activities and encouraging research laboratories and industry to establish co-operation with the international CFD community. The projects of the programme focus on the following areas: (1) studies of modeling the physics and dynamics of the behaviour of fluid material, (2) expressing the physical models in a numerical mode and developing a computer codes, (3) evaluating and testing current physical models and developing new ones, (4) developing new numerical algorithms, solvers, and pre- and post-processing software, and (5) applying the new computational tools to problems relevant to their ultimate industrial use. The report consists of two sections. The first considers issues concerning the whole programme and the second reviews each project
CFD and thermal analysis applications at General Motors
International Nuclear Information System (INIS)
Johnson, J.P.
2002-01-01
The presentation will include a brief history of the growth of CFD and thermal analysis in GM's vehicle program divisions. Its relationship to the underlying computer infrastructure will be sketched. Application results will be presented for calculations in aerodynamics, flow through heat exchangers, engine compartment thermal studies, HVAC systems and others. Current technical challenges will be outlined including grid generation, turbulence modeling, heat transfer, and solution algorithms. The introduction of CFD and heat transfer results into Virtual Vehicle Reviews, and its potential impact on a company's CAE infrastructure will be noted. Finally, some broad comments will be made on the management of CFD and heat transfer technology across a global corporate enterprise. (author)
CULTIVOS BAJO CUBIERTA EN EL SURESTE DE ESPAÑA
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Encarnación Gil Meseguer
2011-01-01
Full Text Available En España, más de 62.000 ha regadas se cultivan en ambiente controlado, bajo determinadas cubiertas. Dos tercios se localizan en Andalucía, y más de la cuarta parte, en el Sureste de la Península Ibérica. En el espacio surestino, delimitado por la coincidencia de las isolíneas climáticas (isoyeta de los 400 mm anuales e isoterma de 16ºC de TMA y la línea de costa mediterránea entre Almería y Alicante, sobresalen una serie de estructuras con cubiertas de plásticos y mallas para la producción de cultivos intensivos en las comarcas del Levante Almeriense-Bajo Almanzora, Lorca y Valle Guadalentín, Campo de Cartagena-Mar Menor, Meridional de Alicante-Vega Baja, etc. Los avances tecnológicos aplicados al riego y al ciclo natural de la planta, se incorporan al cultivo forzado bajo cubierta, logrando modificar el ciclo de cultivo, con una amplitud en los calendarios para presentar el producto en los momentos de mayor demanda. El interés de esta agricultura intensiva de invernaderos, mallas y acolchados radica en su mayor productividad, empleo y precio final del producto.
Extending the capabilities of CFD codes to assess ash related problems
DEFF Research Database (Denmark)
Kær, Søren Knudsen; Rosendahl, Lasse Aistrup; Baxter, B. B.
2004-01-01
This paper discusses the application of FLUENT? in theanalysis of grate-fired biomass boilers. A short description of theconcept used to model fuel conversion on the grate and the couplingto the CFD code is offered. The development and implementation ofa CFD-based deposition model is presented...... in the reminder of thepaper. The growth of deposits on furnace walls and super heatertubes is treated including the impact on heat transfer rates determinedby the CFD code. Based on the commercial CFD code FLUENT?,the overall model is fully implemented through the User DefinedFunctions. The model is configured...
LA INSATISFACCIÓN LABORAL COMO FACTOR DEL BAJO RENDIMIENTO DEL TRABAJADOR
Granda Carazas, Segundo Eloy
2014-01-01
El tema "la insatisfacción laboral como factor del bajo rendimiento del trabajador" es importante, ya que se puede constatar que en algunas organizaciones, pese a sus significativos esfuerzos para ampliar y modernizar su infraestructura, afrontan problemas de rendimiento laboral. Este artículo se orienta a determinar en qué medida la insatisfacción laboral se asocia al bajo rendimiento laboral en una organización. Como factores constituyentes de la insatisfacción laboral se considerar...
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Miriam Gonçalves Miguel
2001-05-01
Full Text Available No Campo Experimental de Engenharia Geotécnica (CEEG da Universidade Estadual de Londrina (UEL, Estado do Paraná, onde o perfil do subsolo se apresenta com uma camada superficial de solo argiloso, poroso e colapsível, com consistência de mole a média, foram realizadas e analisadas quatro provas de carga horizontal em pares de estacas escavadas a trado mecânico, com a finalidade de se obter o coeficiente de reação horizontal do solo (nh e sua variação quanto ao efeito da colapsibilidade. Os resultados das provas de carga horizontal são apresentados através das curvas carga versus deslocamento horizontal do solo, em duas condições: sem inundação e com pré-inundação por 48 horas. O efeito da colapsibilidade do solo é analisado pela redução da capacidade de carga horizontal, determinada pela comparação entre as cargas de ruptura e de colapso obtidas nessas provas de carga. Os resultados das provas de carga permitiram também determinar as curvas do coeficiente de reação horizontal (nh versus o deslocamento horizontal junto à superfície do terreno (yo, considerando a rigidez à flexão da estaca constante com a fissuração do concreto. Na determinação dos valores médios de (nh, foram considerados os intervalos de (yo de 6 a 12 mm (solo não inundado e de 12 a 18 mm (solo inundado
Three-dimensional modeling of pavement with dual load using finite element
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Wilson Rodríguez-Calderón
2015-01-01
Full Text Available El modelo desarrollado busca prede cir los esfuerzos y deformaci ones de un pavimento de manera más real, realizando un análisis elástico tridimensional con solicitaciones de carga de ejes dobles, cons tituyéndose en un avance respect o de modelos axisimétricos bidimensionales que s ólo representan el comportamiento bajo car gas de ejes sencillos. Etapas anteriores de esta investigación dan cuenta de modelos bidimensionales de carga simple bajo distintas hipót esis de liga entre capas y modelo s constitutivos no lineales, n o obstante, el propósito es avanzar en la met odología de análisis del estad o tensodeformacional ante cargas estándar. El modelo se implem entó en el programa Algor y se realizó una comparación con el programa multicapa de dist ribución libre Elsym5 . Los resultados advierten la existencia de concentraciones de esfuerzos de corte en la capa asfáltica que pueden ser causantes de fallas importantes que no son tenidas en cuenta en los tradicionale s métodos de diseño lo cual podría llevar a la posibilidad de revaluarlos.
A CFD study of Screw Compressor Motor Cooling Analysis
Branch, S.
2017-08-01
Screw compressors use electric motors to drive the male screw rotor. They are cooled by the suction refrigerant vapor that flows around the motor. The thermal conditions of the motor can dramatically influence the performance and reliability of the compressor. The more optimized this flow path is, the better the motor performance. For that reason it is important to understand the flow characteristics around the motor and the motor temperatures. Computational fluid dynamics (CFD) can be used to provide a detailed analysis of the refrigerant’s flow behavior and motor temperatures to identify the undesirable hot spots in the motor. CFD analysis can be used further to optimize the flow path and determine the reduction of hot spots and cooling effect. This study compares the CFD solutions of a motor cooling model to a motor installed with thermocouples measured in the lab. The compressor considered for this study is an R134a screw compressor. The CFD simulation of the motor consists of a detailed breakdown of the stator and rotor components. Orthotropic thermal conductivity material properties are used to represent the simplified motor geometry. In addition, the analysis includes the motor casings of the compressor to draw heat away from the motor by conduction. The study will look at different operating conditions and motor speeds. Finally, the CFD study will investigate the predicted motor temperature change by varying the vapor mass flow rates and motor speed. Recommendations for CFD modeling of such intricate heat transfer phenomenon have thus been proposed.
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Yenny Marcela Barreto Zorza
2017-04-01
Full Text Available Introducción: El envejecimiento poblacional dado por la transición demográfica y epidemiológica, repercute en la dependencia de las actividades de la vida diaria de los adultos mayores, requiriendo de manera constante los cuidados de personas denominadas “cuidadores”, en quienes se genera una carga que afecta su salud física y mental. Objetivo: Evaluar la efectividad de un programa en la carga de cuidado para cuidadores familiares en tres grupos culturalmente diversos. Metodología: Investigación cuantitativa, de tipo analítico, a partir de los resultados de tres estudios cuasiexperimentales de grupos de cuidadores familiares de personas ancianas dependientes funcionalmente. Participaron 88 cuidadores de tres municipios: Bogotá, Cáqueza y Guapi, en un Programa educativo con acciones de cuidado adaptadas culturalmente. La información se recolectó con la Escala de carga de Zarit, antes y después de la implementación del programa, se realizó un análisis con prueba de rango signado de Wilcoxon en cada uno de los tres grupos. Se consideró aspectos éticos. Resultados: El programa educativo para cuidadoras familiares tuvo un efecto estadísticamente significativo en la carga de cuidado de los cuidadores de Cáqueza (valor p 0.014, posiblemente porque el programa responde a una de las necesidades prioritarias de estos cuidadores que es el cuidado de sí mismos, contrario al encontrado en Bogotá y Guapi. Lo que sugiere continuar estudios con programas a cuidadores con perspectiva cultural. Conclusión: El logro de resultados estadísticamente significativos en las cuidadoras de Cáqueza sugiere que ellas cuentan con una mejor red de apoyo familiar y vecinal, por eso asumen la asistencia al programa con mayor dedicación, integralidad y disposición de tiempo.
A CFD validation roadmap for hypersonic flows
Marvin, Joseph G.
1993-01-01
A roadmap for computational fluid dynamics (CFD) code validation is developed. The elements of the roadmap are consistent with air-breathing vehicle design requirements and related to the important flow path components: forebody, inlet, combustor, and nozzle. Building block and benchmark validation experiments are identified along with their test conditions and measurements. Based on an evaluation criteria, recommendations for an initial CFD validation data base are given and gaps identified where future experiments would provide the needed validation data.
Efficient Turbulence Modeling for CFD Wake Simulations
DEFF Research Database (Denmark)
van der Laan, Paul
Wind turbine wakes can cause 10-20% annual energy losses in wind farms, and wake turbulence can decrease the lifetime of wind turbine blades. One way of estimating these effects is the use of computational fluid dynamics (CFD) to simulate wind turbines wakes in the atmospheric boundary layer. Since...... this flow is in the high Reynolds number regime, it is mainly dictated by turbulence. As a result, the turbulence modeling in CFD dominates the wake characteristics, especially in Reynolds-averaged Navier-Stokes (RANS). The present work is dedicated to study and develop RANS-based turbulence models...... verified with a grid dependency study. With respect to the standard k-ε EVM, the k-ε- fp EVM compares better with measurements of the velocity deficit, especially in the near wake, which translates to improved power deficits of the first wind turbines in a row. When the CFD metholody is applied to a large...
Capacidad de carga estática en rodamientos. Normalización y tendencias.
Directory of Open Access Journals (Sweden)
A. García Toll
2007-01-01
Full Text Available Para ilustrar la funcionalidad de la norma NC-ISO 76: 2006, establecida a partir de una adopción idéntica de la Norma ISO 76: 1987/ amd.1: 1999 (E “Cojinetes de Rodamiento – Capacidad de Carga Estática”, son mostradas las correspondencias entre las magnitudes de capacidad de carga estática declaradas en los catálogos técnicos de reconocidos fabricantes de rodamientos con los valores presentes en NC-ISO 76 y considerando diferentes geometrías de rodamientos radiales de bolas rígidos y de contacto angular, rodamientos axiales de bolas y rodamientos de rodillos cilíndricos. Adicionalmente, el estudio ha permitido establecer las dependencias entre la capacidad de carga nominal estática del rodamiento y algunos parámetros geométricos, como el diámetro del elemento rodante, el diámetro interior y la relación diámetro interior - diámetro exterior del cojinete.At the present time, Standard NC-ISO 76: 2006 is a national standard established as identical adoption of ISO standard 76:1987 / amd.1: 1999 (E "Rolling Bearings - Static Load Rating¨. In this sense, the static load rating of rolling bearings declared in technical catalogs of renowned bearing manufacturers and the basic static load rating according to calculation procedures stated in Standard NC-ISO 76 are compared. The evaluation has taken into account different geometries of radial groove ball bearings, angular contact ball bearings, thrust ball bearings and radial roller bearings. Additionally, they are established dependences between the static load rating of rolling bearings and the interior diameter of different types of radial and thrust bearings.
Análise da carga de trabalho de analistas de sistemas e dos distúrbios osteomusculares
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Bruno Maia de Guimarães
Full Text Available OBJETIVOS: O objetivo desta pesquisa foi realizar avaliação das condições ergonômicas de analistas de sistemas, com a finalidade de conhecer os fatores geradores de sobrecargas físicas e cognitivas, suas repercussões sobre os trabalhadores e propor melhorias para a diminuição dessas sobrecargas. METODOLOGIA: Foram utilizados o método SHTM (sistema homem-tarefa-máquina de avaliação ergonômica; o diagrama de Corlett, para a avaliação do desconforto corporal; o questionário de avaliação do mobiliário; e o NASA-TLX, para a avaliação de carga mental de trabalho. RESULTADOS: Foram encontradas as prevalências de dor na coluna lombar (71% e na coluna cervical (64% dos entrevistados. Após a avaliação da carga mental de trabalho, foi observado que a demanda mental foi a mais exigida entre os analistas de sistemas e a média da carga global foi de 13,23. CONCLUSÃO: Pode-se concluir que a alta prevalência de dor musculoesquelética pode ser causada pela presença de mobiliário inadequado, pela adoção de posturas incorretas e pela alta exigência mental das atividades desenvolvidas.
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Arystides Resende Silva
2011-06-01
Full Text Available A operação de baldeio florestal está relacionada ao uso de máquinas, as quais trafegam numa mesma linha várias vezes ou aleatoriamente, o que pode causar compactação do solo, alterando o meio onde o sistema radicular se desenvolve e reduzindo a produtividade. Além do número de passadas, a carga de madeira transportada pode afetar a compactação do solo quando as pressões aplicadas pelas máquinas excederem a capacidade de suporte de carga desse solo. Os objetivos deste estudo foram: a propor modelo de capacidade de suporte de carga para Latossolo Vermelho-Amarelo no Município de Santa Maria de Itabira, MG, em razão da pressão de pré-consolidação e da umidade; e b determinar, com o uso deste modelo, o efeito da intensidade de tráfego e da carga de Forwarder sobre a estrutura do solo. Para a obtenção dos modelos de capacidade de suporte de carga, 20 amostras indeformadas de solo foram coletadas nas profundidades de 0-3 e 10-13 cm no local onde não houve tráfego. Foram também coletadas 10 amostras indeformadas em cada profundidade, onde o Forwarder trafegou duas, quatro e oito vezes e no local onde o Forwarder trafegou quatro vezes com 1/3 (3 m³, 2/3 (6 m³ e 3/3 (9 m³ de sua carga. As amostras indeformadas foram utilizadas nos ensaios de compressão uniaxial. Determinaram-se também a textura, o teor de matéria orgânica e a densidade de partículas e densidade dos solos. O modelo de capacidade de suporte de carga do LVA é expresso pela equação s p = 10(2,71 - 1,36 U. Todas as intensidades de tráfego causaram compactação no solo nas duas profundidades estudadas, sendo quatro passadas as que causaram maior compactação do solo, e, à medida que a carga do Forwarder aumentou, a compactação do solo também aumentou nas duas profundidades.
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Hugo Rondón
2014-01-01
Full Text Available El artículo presenta el diseño y la construcción de un prototipo con el cual es posible medir cargas vehiculares en un pavimento flexible, a partir de las vibraciones que dichos vehículos generan cuando se movilizan sobre esta estructura vial. El principio físico es simple: cuando un vehículo circula sobre la superficie de un pavimento, éste genera vibraciones que pueden ser percatadas en zonas adyacentes a la vía en estudio, y las amplitudes de dichas deformaciones pueden dar información sobre la magnitud de la carga rodante. Adicionalmente, se reportan los resultados de un estudio de campo ejecutado con el fin de calibrar una ecuación matemática que simula las señales de vibración obtenidas con el prototipo. De manera general se concluye que el prototipo es capaz de predecir la carga que circula sobre el pavimento a partir de las vibraciones que éstos inducen cuando transitan sobre la capa de rodadura.
CFD-model of the mass transfer in the vertical settler
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E. K. Nagornaya
2013-02-01
Full Text Available Purpose. Nowadays the mathematical models of the secondary settlers are intensively developed. As a rule the engineers use the 0-D models or 1-D models to design settlers. But these models do not take into account the hydrodynamics process inside the settler and its geometrical form. That is why the CFD-models based on Navier - Stokes equations are not widely used in practice now. The use of CFD-models based on Navier - Stokes equations needs to incorporate very refine grid. It is very actually now to develop the CFD-models which permit to take into account the geometrical form of the settler, the most important physical processes and needs small computer time for calculation. That is why the development of the 2-D numerical model for the investigation of the waste waters transfer in the vertical settlers which permits to take into account the geometrical form and the constructive features of the settler is essential. Methodology. The finite - difference schemes are applied. Findings. The new 2-D-CFD-model was developed, which permits to perform the CFD investigation of the vertical settler. This model takes into account the geometrical form of the settler, the central pipe inside it and others peculiarities. The method of «porosity technique» is used to create the geometrical form of the settler in the numerical model. This technique permits to build any geometrical form of the settler for CFD investigation. Originality. Making of CFD-model which permits on the one hand to take into account the geometrical form of the settler, basic physical processes of mass transfer in construction and on the other hand requiring the low time cost in order to obtain results. Practical value. CFD-model is designed and code which is constructed on its basis allows at low cost of computer time and about the same as in the calculation of the 1-D model to solve complex multiparameter problems that arise during the design of vertical settlers with their shape and
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Santiago Correa Vélez
2013-03-01
Full Text Available Objetivo: determinar por el método de los elementos finitos la resistencia de dientes restaurados con postes prefabricados ante cargas estáticas de máxima intercuspidación y cargas cíclicas de masticación y bruxismo y analizar el efecto de la pérdida periodontal en la resistencia de las restauraciones. Métodos: se realizó una investigación in vitro mediante el método de los elementos finitos de dientes con pérdida periodontal, rehabilitados con postes prefabricados en fibra de vidrio, carbono y titanio. Los dientes fueron reconstruidos a partir de imágenes tomográficas de un paciente periodontalmente sano. Resultados: se muestra que ante cargas estáticas las rehabilitaciones no presentan tendencia a la falla, independientemente del material del poste o del grado de pérdida periodontal. En el caso de bruxismo y pérdida periodontal de 4 mm, la dentina presenta una durabilidad de 60 000 ciclos independiente del material del poste. Para cargas de masticación y periodonto sano, la falla en la dentina ocurre a los 100 000 ciclos con poste en titanio, 200 000 ciclos con poste en fibra de carbono y 1 100 000 ciclos con poste en fibra de vidrio. Para una pérdida periodontal de 2 mm la durabilidad de la dentina se reduce a 4 000 ciclos con poste en titanio, 5 000 ciclos con poste en fibra de carbono y 7 000 ciclos con poste en fibra de vidrio. Para pérdida periodontal de 4 mm, la durabilidad de la dentina se estima en 1 000 ciclos, independientemente del material del poste utilizado. Conclusiones: ante carga estática de máxima intercuspidación las rehabilitaciones con postes prefabricados en fibra de vidrio, carbono y titanio no presentan tendencia a la falla, independientemente del grado de pérdida periodontal. Ante cargas cíclicas, los postes prefabricados presentan una vida útil infinita, y es la dentina la estructura más afectada ante dichos eventos.
CFD analyses of steam and hydrogen distribution in a nuclear power plant
International Nuclear Information System (INIS)
Siccama, N.B.; Houkema, M.; Komen, E.M.J.
2003-01-01
A detailed three-dimensional Computational Fluid Dynamics (CFD) model of the containment of the nuclear power plant has been prepared in order to assess possible multidimensional phenomena. In a first code-to-code comparison step, the CFD model has been used to compute a reference accident scenario which has been analysed earlier with the lumped parameter code SPECTRA. The CFD results compare qualitatively well with the SPECTRA results. Subsequently, the actual steam jet from the primary system has been modelled in the CFD code in order to determine the hydrogen distribution for this realistically modelled source term. Based on the computed hydrogen distributions, it has been determined when use of lumped parameter codes is allowed and when use of CFD codes is required. (author)
Bajo rendimiento escolar: una perspectiva desde el desarrollo del sistema nervioso
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K. Shapiro Bruce, MD.
2011-03-01
Full Text Available El bajo rendimiento escolar es un problema frecuente y tiene múltiples causas; las alteraciones que lo caracterizan, se expresan fundamentalmente en las áreas de funcionamiento cognitivo, académico y conductual. El bajo rendimiento escolar es una vía final común de diferentes trastornos, etiologías y mecanismos. Es habitual la presencia de múltiples alteraciones, porque la disfunción cerebral en la niñez generalmente afecta a muchas funciones. Consecuente con lo anterior, los programas de manejo deben ser individualizados, comprensivos e incorporar aspectos del niño en particular, la escuela y la familia. La planificación del tratamiento incluye, educación y entrenamiento de los padres, adecuaciones académicas, técnicas para mantener la autoestima y un enfoque psicofarmacológico. Es necesario monitorear en forma continua los programas de manejo especialmente para detectar comorbilidades importantes que puedan emerger, para realizar modificaciones que se adecuen a los cambios en las demandas académicas y sociales a las diferentes edades del niño y para proveer de información actualizada. Las consecuencias que tenga el bajo rendimiento escolar para el niño dependerán en medida importante de las alteraciones subyacentes. El personal de salud tiene múltiples roles en la prevención, detección, diagnóstico y manejo del niño con bajo rendimiento escolar.
Tensão e cargas superficiais – o que Wilhelm Weber já sabia há 150 anos
Directory of Open Access Journals (Sweden)
Hermann Härtel
2012-12-01
Full Text Available http://dx.doi.org/10.5007/2175-7941.2012v29n3p1015 É apresentada uma descrição qualitativa da voltagem elétrica em termos da existência de cargas superficiais, antes de se introduzir a definição abstrata de “habilidade de realizar trabalho por uma fonte de energia” ou a definição quantitativa com “energia por unidade de carga”. Essas cargas superficiais e os campos elétricos associados a elas podem ser demonstradas experimentalmente e fornecem uma explicação causal dos processos e das leis que precisam ser compreendidos e aprendidos.
Estratificación del bajo peso al nacer desde un enfoque de determinantes sociales
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Hilda María Delgado Acosta
2013-03-01
Full Text Available Fundamento: el área materno-infantil requiere de un enfoque en sus determinantes para aumentar el alcance estratégico de sus programas. Objetivo: estratificar el bajo peso al nacer en el municipio de Cienfuegos y caracterizar el bajo peso de acuerdo a determinantes sociales seleccionadas. Métodos: se realizó un estudio epidemiológico, descriptivo, correlacional sobre la estratificación del bajo peso al nacer en los consejos populares del municipio Cienfuegos, en el período comprendido entre los años 2003 y 2007. Los estratos se definieron según el valor de la media del índice de bajo peso al nacer en este periodo. Para realizar el análisis de las variables cualitativas en muestras independientes se utilizó la prueba de independencia u homogeneidad utilizada en el caso de dos muestras con resultado dicotómico o más. El procesamiento estadístico se realizó en el programa SPSS versión 15,0 y se utilizaron como medidas matemáticas para las variables cualitativas el porcentaje, y para las variables cuantitativas la media aritmética. La técnica estadística para relacionar las variables fue la prueba Chi-cuadrado. Resultados: se mostraron diferencias estadísticamente significativas entre los estratos de bajo, mediano y alto riesgo, en el nivel de escolaridad, estado civil, ocupación, evaluación nutricional, hábito de fumar, antecedentes de bajo peso al nacer, período ínter genésico. La única enfermedad asociada que mostró diferencias entre ellos fue la hipertensión gestacional. Conclusiones: el bajo peso al nacer continúa siendo un serio problema de salud en el municipio Cienfuegos, cuestión esta que debe ser abordada desde sus determinantes para realizar intervenciones futuras y el logro de mejores resultados.
PLANIFICACIÓN JERÁRQUICA CON ANÁLISIS DE CARGA-CAPACIDAD
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Tulio Gerardo Motoa
2001-01-01
Full Text Available La planificación jerárquica de múltiples proyectos, surge como una opción robusta y potente, para resolver el problema de gestión del sistema global. La propuesta se basa en la construcción de una estructura de descomposición-agregación de los proyectos y los recursos, con múltiples niveles, en la cual, los niveles más altos presentan los datos más agregados, con horizontes de tiempo más largos y los niveles inferiores son más detallados y con horizontes más cortos. Dentro del ámbito de la planificación jerárquica, el análisis de carga-capacidad pretende fundamentalmente mejorar la relación entre la oferta y la demanda de recursos en los procesos de planificación de proyectos, de tal manera que se garantice el cumplimiento de las fechas ya establecidas. Este análisis, se implementa midiendo algunos indicadores que reflejan el estado de la relación entre la carga y la capacidad y ejecutando un procedimiento de nivelación que avanza en el equilibrio de tal estado. El procedimiento de análisis se ha experimentado mediante un conjunto de proyectos generados aleatoriamente y los resultados son bastante buenos.
Case studies from the REHVA CFD guide book
DEFF Research Database (Denmark)
Nielsen, Peter V.
2008-01-01
This paper presents CFD predictions which are used at different levels, from the evaluation of an idea to the design of a system, or for the analysing work on an existing building.......This paper presents CFD predictions which are used at different levels, from the evaluation of an idea to the design of a system, or for the analysing work on an existing building....
The application of CFD to hydrogen risk analysis in nuclear power plants
International Nuclear Information System (INIS)
Wang Hui; Han Xu; Chang Meng; Wang Xiaofeng; Wang Shuguo; Lu Xinhua; Wu Lin
2013-01-01
Status of the hydrogen risk analysis method is systemically summarized in this paper and the advantages and limits of CFD (Computational Fluid Dynamic) in hydrogen risk analysis is discussed. The international experimental programs on the CFD hydrogen risk analysis are introduced in this paper. The application of CFD to nuclear power plant (NPP) hydrogen risk analysis is introduced in detail by taking EPR and Ling'ao NPP for example. In these bases, the CFD development prospect of hydrogen risk analysis is also summarized in this paper. (authors)
CFD modeling and experience of waste-to-energy plant burning waste wood
DEFF Research Database (Denmark)
Rajh, B.; Yin, Chungen; Samec, N.
2013-01-01
Computational Fluid Dynamics (CFD) is being increasingly used in industry for in-depth understanding of the fundamental mixing, combustion, heat transfer and pollutant formation in combustion processes and for design and optimization of Waste-to-Energy (WtE) plants. In this paper, CFD modeling...... the conversion of the waste wood in the fuel bed on the grate, which provides the appropriate inlet boundary condition for the freeboard 3D CFD simulation. The CFD analysis reveals the detailed mixing and combustion characteristics in the waste wood-fired furnace, pinpointing how to improve the design...
Funciones de costos internos y externos en un modelo estratégico de transporte de carga
Directory of Open Access Journals (Sweden)
Luis Gabriel Márquez Díaz
2010-11-01
Full Text Available Se revisan las funciones de costos internos y externos,con fines de modelación estratégica del transportede carga. Se estudian el costo interno del tiempo, elcosto interno de operación y cinco componentes delcosto externo: costo externo de la congestión, costoexterno de los accidentes, costos de la polución delaire, costo del cambio climático y costo externo dela infraestructura; a partir de estos se deriva la funciónde costo marginal total. Se encuentra que es posibleestimar de forma empírica los parámetros de lasfunciones aplicables al transporte de cargainterregional en Colombia en los modos de transportecarretero, ferroviario y fluvial, y con ellos estudiarlos costos marginales sobre una red estratégica detransporte de carga.
Application of Simple CFD Models in Smoke Ventilation Design
DEFF Research Database (Denmark)
Brohus, Henrik; Nielsen, Peter Vilhelm; la Cour-Harbo, Hans
2004-01-01
The paper examines the possibilities of using simple CFD models in practical smoke ventilation design. The aim is to assess if it is possible with a reasonable accuracy to predict the behaviour of smoke transport in case of a fire. A CFD code mainly applicable for “ordinary” ventilation design...
Directory of Open Access Journals (Sweden)
Letícia de Lima Trindade
2013-01-01
Full Text Available Analiza la influencia de dos modelos asistenciales, que se utilizan en la atención primaria, en las cargas de trabajo de los profesionales de la salud. Investigación cualitativa realizada con los equipos de Salud de la Familia y el modelo tradicional detrabajar en Atención Primaria de Salud en el sur de Brasil. Para la obtención y procesamiento de los datos se utilizaron entrevistas, grupos focales y estudios documentales, analizados mediante la combinación de un análisis de contenido con el software AtlasTi. Los resultados mostraran que en ambos modelos, los problemas de organización y gestión de la asistencia, el exceso de demanda y la baja resolución son las principales fuentes de aumento de las cargas de trabajo, por locontrario como fuente de reducción de la carga laboral se presentaron la afinidad con el modelo de atención y el trabajo en equipo. Llegamos a la conclusión de que el aumento de la carga laboral en salud de la familia se vio afectada por la distancia entre lo prescrito y lo realizado, y en cuanto al modelo tradicional se debió a que este está basado en el modelo biomédico.
CFD analyses in regulatory practice
International Nuclear Information System (INIS)
Bloemeling, F.; Pandazis, P.; Schaffrath, A.
2012-01-01
Numerical software is used in nuclear regulatory procedures for many problems in the fields of neutron physics, structural mechanics, thermal hydraulics etc. Among other things, the software is employed in dimensioning and designing systems and components and in simulating transients and accidents. In nuclear technology, analyses of this kind must meet strict requirements. Computational Fluid Dynamics (CFD) codes were developed for computing multidimensional flow processes of the type occurring in reactor cooling systems or in containments. Extensive experience has been accumulated by now in selected single-phase flow phenomena. At the present time, there is a need for development and validation with respect to the simulation of multi-phase and multi-component flows. As insufficient input by the user can lead to faulty results, the validity of the results and an assessment of uncertainties are guaranteed only through consistent application of so-called Best Practice Guidelines. The authors present the possibilities now available to CFD analyses in nuclear regulatory practice. This includes a discussion of the fundamental requirements to be met by numerical software, especially the demands upon computational analysis made by nuclear rules and regulations. In conclusion, 2 examples are presented of applications of CFD analysis to nuclear problems: Determining deboration in the condenser reflux mode of operation, and protection of the reactor pressure vessel (RPV) against brittle failure. (orig.)
Application perspectives of simulation techniques CFD in nuclear power plants
International Nuclear Information System (INIS)
Galindo G, I. F.
2013-10-01
The scenarios simulation in nuclear power plants is usually carried out with system codes that are based on concentrated parameters networks. However situations exist in some components where the flow is predominantly 3-D, as they are the natural circulation, mixed and stratification phenomena. The simulation techniques of computational fluid dynamics (CFD) have the potential to simulate these flows numerically. The use of CFD simulations embraces many branches of the engineering and continues growing, however, in relation to its application with respect to the problems related with the safety in nuclear power plants, has a smaller development, although is accelerating quickly and is expected that in the future they play a more emphasized paper in the analyses. A main obstacle to be able to achieve a general acceptance of the CFD is that the simulations should have very complete validation studies, sometimes not available. In this article a general panorama of the state of the methods application CFD in nuclear power plants is presented and the problem associated to its routine application and acceptance, including the view point of the regulatory authorities. Application examples are revised in those that the CFD offers real benefits and are also presented two illustrative study cases of the application of CFD techniques. The case of a water recipient with a heat source in its interior, similar to spent fuel pool of a nuclear power plant is presented firstly; and later the case of the Boron dilution of a water volume that enters to a nuclear reactor is presented. We can conclude that the CFD technology represents a very important opportunity to improve the phenomena understanding with a strong component 3-D and to contribute in the uncertainty reduction. (Author)
The role of CFD computer analyses in hydrogen safety management
International Nuclear Information System (INIS)
Komen, E.M.J; Visser, D.C; Roelofs, F.; Te Lintelo, J.G.T
2014-01-01
The risks of hydrogen release and combustion during a severe accident in a light water reactor have attracted considerable attention after the Fukushima accident in Japan. Reliable computer analyses are needed for the optimal design of hydrogen mitigation systems, like e.g. passive autocatalytic recombiners (PARs), and for the assessment of the associated residual risk of hydrogen combustion. Traditionally, so-called Lumped Parameter (LP) computer codes are being used for these purposes. In the last decade, significant progress has been made in the development, validation, and application of more detailed, three-dimensional Computational Fluid Dynamics (CFD) simulations for hydrogen safety analyses. The objective of the current paper is to address the following questions: - When are CFD computer analyses needed complementary to the traditional LP code analyses for hydrogen safety management? - What is the validation status of the CFD computer code for hydrogen distribution, mitigation, and combustion analyses? - Can CFD computer analyses nowadays be executed in practical and reliable way for full scale containments? The validation status and reliability of CFD code simulations will be illustrated by validation analyses performed for experiments executed in the PANDA, THAI, and ENACCEF facilities. (authors)
CFD Analysis of the Safety Injection Tank and Fluidic Device
Energy Technology Data Exchange (ETDEWEB)
Cho, Jai Oan; Nietiadi, Yohanes Setiawan; Lee, Jeong Ik [KAIST, Daejeon (Korea, Republic of); Addad, Yacine [KUSTAR, Abu Dhabi (United Arab Emirates)
2016-05-15
One of the most important components in the ECCS is the safety injection tank (SIT). Inside the SIT, a fluidic device is installed, which passively controls the mass flow of the safety injection and eliminates the need for low pressure safety injection pumps. As more passive safety mechanisms are being pursued, it has become more important to understand flow structure and the loss mechanism within the fluidic device. Current computational fluid dynamics (CFD) calculations have had limited success in predicting the fluid flow accurately. This study proposes to find a more exact result using CFD and more realistic modeling to predict the performance during accident scenarios more accurately. The safety injection tank with fluidic device was analyzed thoroughly using CFD. The preliminary calculation used 60,000 meshes for the initial test calculation. The results fit the experimental results surprisingly despite its coarse grid. Nonetheless, the mesh resolution was increased to capture the vortex in the fluidic device precisely. Once a detailed CFD computation is finished, a small-scale experiment will be conducted for the given conditions. Using the experimental results and the CFD model, physical models can be improved to fit the results more accurately.
Martínez López, Nuria
2017-01-01
Las familias y las mujeres en particular, que trabajan fuera del hogar, necesitan conciliar no solo el trabajo y las responsabilidades familiares, también el área personal o tiempo dedicado a sí mismas. La profesión enfermera, mayoritariamente femenina y con una elevada carga física y emocional, resulta el marco idóneo para estudiar cómo se concilia el área personal, familiar y profesional, así como los aspectos que influyen en la conciliación. Hemos estudiado a las enfermeras/os con cargas ...
Álvarez Casado, Enrique
2013-01-01
El levantamiento manual de cargas es un requerimiento de trabajo muy frecuente en Europa y su exposición puede originar importantes daños a la salud, comportando un gran coste socio-económico. En esta investigación, mediante la valoración de expertos y delegados de prevención, se caracterizan las exposiciones a levantamientos manuales de cargas más presentes en las empresas y las prácticas comunes para su evaluación. Se analiza la validez, las limitaciones y la aplicabilidad de los modelos...
Danilo Costa de França
2011-01-01
Objetivou-se estudar o comportamento de estacas escavadas de grande diâmetro em uma obra de um Shopping Center na cidade de São Paulo. As estacas foram submetidas a carregamentos axiais de compressão, sendo que as estacas foram instrumentadas em profundidade. Utilizou-se de teorias amplamente conhecidas no meio técnico com o propósito de interpretar as curvas carga vs recalque, obtendo-se resultados como os diagramas de transferência de carga ao longo do fuste e atrito lateral unitário, gráfi...
Povinelli, Louis A.
1991-01-01
An overview is given of research activity on the application of computational fluid dynamics (CDF) for hypersonic propulsion systems. After the initial consideration of the highly integrated nature of air-breathing hypersonic engines and airframe, attention is directed toward computations carried out for the components of the engine. A generic inlet configuration is considered in order to demonstrate the highly three dimensional viscous flow behavior occurring within rectangular inlets. Reacting flow computations for simple jet injection as well as for more complex combustion chambers are then discussed in order to show the capability of viscous finite rate chemical reaction computer simulations. Finally, the nozzle flow fields are demonstrated, showing the existence of complex shear layers and shock structure in the exhaust plume. The general issues associated with code validation as well as the specific issue associated with the use of CFD for design are discussed. A prognosis for the success of CFD in the design of future propulsion systems is offered.
Flask fluid flow simulation using CFD
International Nuclear Information System (INIS)
Swindlehurst, W.E.; Livesey, E.; Worthington, D.
1989-01-01
BNFL and its subsidiary Company, PNTL, design and operate waterfilled LWR fuel transport flasks for the international transport of irradiated fuel. Although some 150 flasks are currently in operation, new flask designs are being developed. As part of the supporting R and D program, Computational Fluid Dynamics (CFD) codes are being investigated as a means of predicting fluid movements and temperatures within the complex internal geometry of flasks. The ability to simulate fluid flow is particularly important when convection heat transfer is significant. Although obviously relevant to water filled flasks, the technique is applicable to dry flask thermal assessments (where experience shows that convection heat transfer is often underestimated). Computational Fluid Dynamics has emerged in recent years as an important technique in engineering design and safety assessments. Cheaper computing and the development of general CFD codes allows complex engineering structures to be analyzed. However, because of this complexity, it is essential that the application and associated modeling assumptions are critically reviewed. To assess the ability of a CFD code to model flask internals, the code PHOENICS has been used to model the fluid movements in a BNFL Excellox-type flask and the results compared with test data
MODELLING MANTLE TANKS FOR SDHW SYSTEMS USING PIV AND CFD
DEFF Research Database (Denmark)
Shah, Louise Jivan; Morrison, G.L.; Behnia, Masud
1999-01-01
Characteristics of vertical mantle heat exchanger tanks for SDHW systems have been investigated experimentally and theoretically using particle image velocimetry (PIV) and CFD modelling. A glass model of a mantle heat exchanger tank was constructed so that the flow distribution in the mantle could...... be studied using the PIV test facility. Two transient three-dimensional CFD-models of the glass model mantle tank were developed using the CFD-programmes CFX and FLUENT.The experimental results illustrate that the mantle flow structure in the mantle is complicated and the distribution of flow in the mantle...
Numerical analysis for simulation of condensing vapor bubble using CFD-ACE+
International Nuclear Information System (INIS)
Goyal, P.; Dutta, Anu; Singh, R.K.
2014-01-01
The motion of bubbles is very complex. They may be subject to break-up or coalescence and may appear to move with a spiraling, zigzagging or rocking behavior. Recently, many studies have been carried out to numerically simulate the rising bubble in various conditions by using VOF approach. However, all the above studies were limited to adiabatic bubble where heat and mass transfer between the phases were not considered. In the present work, an attempt was made to capture the behaviour of condensing bubble flowing in a channel, by using commercial CFD code CFD-ACE+ through VOF model. A User-Defined Function was developed to simulate interfacial heat and mass transfer during condensation. The effect of condensation on bubble behavior was analyzed by comparing the behavior of condensing bubble with that of adiabatic bubble. For validation of CFD-ACE UDF of bubble condensation, a comparison was made with the literature quoted experimental data and it agreed well. Through this work an emphasis was put on VOF module along with the development of an UDF for bubble condensation in CFD-ACE+ code. This theoretical study is motivated by the future CFD application and the intent to investigate the capabilities of the CFD-ACE+ package. (author)
The Brent Contract for Differences (CFD)
International Nuclear Information System (INIS)
Barrera-Rey, F.; Seymour, A.
1996-01-01
The market for Brent Contracts-for-Differences (CFDs) emerged as early as 1988 but its significant development did not occur until 1992. By financial market standards, however, this span of life is fairly long. Yet the characteristics and role of this oil trading instrument have not been seriously studied. This study aims at filling a gap in research on the Brent market complex which includes spot trades, a 15-day forward and futures contracts, various derivatives and, finally, the less well documented CFD. Chapters 2 and 3 aim to describe and explain the characteristics of the CFD market, in particular the evolution in contract terms and the composition of participants. (UK)
Teoría de la carga cognitiva, diseño multimedia y aprendizaje: un estado del arte
Directory of Open Access Journals (Sweden)
Luis Alejandro Andrade-Lotero
2012-01-01
Full Text Available En este artículo de revisión se presenta un resumen de la Teoría de la Carga Cognitiva y la Teoría Cognitiva del Aprendizaje Multimedia. Se dan algunos ejemplos de investigaciones empíricas y se reflexiona acerca del valor explicativo de estas teorías del aprendizaje. Se exponen diez principios para el diseño de material instruccional. No obstante, otras investigaciones han encontrado limitaciones en el uso y práctica de estas teorías. Se refieren principalmente a la medición de la carga cognitiva, a la experiencia, al conocimiento previo de los aprendices y a la motivación y aspectos afectivos que intervienen en el proceso de aprendizaje.
Efectos del cumplimiento del Ramadán durante el embarazo sobre el peso al nacer con datos de África
Cantet, María Natalia
2014-01-01
El peso al nacer es una de las medidas más utilizada como proxy de la salud y bienestar infantil en la literatura económica. Aquellos niños con bajo peso al nacer (LBW), convencionalmente definido como menos de 2500 gramos, suelen experimentar efectos severos sobre la salud, la mortalidad, la morbilidad y la discapacidad. Por otro lado, el bajo peso al nacer también se traduce en costos sustanciales en el sector de la salud e impone una carga significativa sobre la sociedad en su conjunto. El...
Assessment of CFD Codes for Nuclear Reactor Safety Problems - Revision 2
International Nuclear Information System (INIS)
Smith, B.L.; Andreani, M.; Bieder, U.; Ducros, F.; Bestion, D.; Graffard, E.; Heitsch, M.; Scheuerer, M.; Henriksson, M.; Hoehne, T.; Houkema, M.; Komen, E.; Mahaffy, J.; Menter, F.; Moretti, F.; Morii, T.; Muehlbauer, P.; Rohde, U.; Krepper, E.; Song, C.H.; Watanabe, T.; Zigh, G.; Boyd, C.F.; Archambeau, F.; Bellet, S.; Munoz-Cobo, J.M.; Simoneau, J.P.
2015-01-01
Following recommendations made at an 'Exploratory Meeting of Experts to Define an Action Plan on the Application of Computational Fluid Dynamics (CFD) Codes to Nuclear Reactor Safety (NRS) Problems', held in Aix-en-Provence, France, 15-16 May, 2002, and a follow-up meeting 'Use of Computational Fluid Dynamics (CFD) Codes for Safety Analysis of Reactor Systems including Containment', which took place in Pisa on 11-14 Nov., 2002, a CSNI action plan was drawn up which resulted in the creation of three Writing Groups, with mandates to perform the following tasks: (1) Provide a set of guidelines for the application of CFD to NRS problems; (2) Evaluate the existing CFD assessment bases, and identify gaps that need to be filled; (3) Summarise the extensions needed to CFD codes for application to two-phase NRS problems. Work began early in 2003. In the case of Writing Group 2 (WG2), a preliminary report was submitted to Working Group on the Analysis and Management of Accidents (WGAMA) in September 2004 that scoped the work needed to be carried out to fulfil its mandate, and made recommendations on how to achieve the objective. A similar procedure was followed by the other two groups, and in January 2005 all three groups were reformed to carry out their respective tasks. In the case of WG2, this resulted in the issue of a CSNI report (NEA/CSNI/R(2007)13), issued in January 2008, describing the work undertaken. The writing group met on average twice per year during the period March 2005 to May 2007, and coordinated activities strongly with the sister groups WG1 (Best Practice Guidelines) and WG3 (Multiphase Extensions). The resulting document prepared at the end of this time still represents the core of the present revised version, though updates have been made as new material has become available. After some introductory remarks, Chapter 3 lists twenty-three (23) NRS issues for which it is considered that the application of CFD would bring real benefits
Bajo Peso al Nacer. Factores de riesgo y calidad de la atención Prenatal. Buenaventura. 2008-2009
Directory of Open Access Journals (Sweden)
Luis Enrique Gallardo-Ibarra
2012-01-01
Full Text Available Se realizó estudio descriptivo sobre Bajo Peso al Nacer, Área de Salud Buenaventura, bienio 2008-2009, sobre factores de riesgo y calidad de la atención médica recibida por las gestantes que aportaron recién nacidos bajo peso. Los datos estadísticos se obtuvieron mediante revisión de historias clínicas familiares, obstétricas y hospitalarias. Se emplearon métodos estadísticos histórico lógico, análisis y síntesis e inducción-deducción. Se obtuvo predominio del CIUR como variedad de Bajo Peso al Nacer, mostraron asociación con el bajo peso al nacer la valoración nutricional Bajo Peso materna al inicio de la gestación, insuficiente ganancia de peso, ingreso percápita bajo, malas condiciones de vivienda, antecedentes de dos o más abortos, multigestación, período intergenésico corto, HTA y sepsis cervicovaginal. La Atención Prenatal fue deficiente. No existió relación entre grupos de edades menores de 20 o mayor de 35 años y hábitos tóxicos con la aparición del bajo peso al nacer.
Assessment of Computational Fluid Dynamics (CFD) Models for Shock Boundary-Layer Interaction
DeBonis, James R.; Oberkampf, William L.; Wolf, Richard T.; Orkwis, Paul D.; Turner, Mark G.; Babinsky, Holger
2011-01-01
A workshop on the computational fluid dynamics (CFD) prediction of shock boundary-layer interactions (SBLIs) was held at the 48th AIAA Aerospace Sciences Meeting. As part of the workshop numerous CFD analysts submitted solutions to four experimentally measured SBLIs. This paper describes the assessment of the CFD predictions. The assessment includes an uncertainty analysis of the experimental data, the definition of an error metric and the application of that metric to the CFD solutions. The CFD solutions provided very similar levels of error and in general it was difficult to discern clear trends in the data. For the Reynolds Averaged Navier-Stokes methods the choice of turbulence model appeared to be the largest factor in solution accuracy. Large-eddy simulation methods produced error levels similar to RANS methods but provided superior predictions of normal stresses.
Caroff, Jildaz; Mihalea, Cristian; Da Ros, Valerio; Yagi, Takanobu; Iacobucci, Marta; Ikka, Léon; Moret, Jacques; Spelle, Laurent
2017-07-01
Recent reports have revealed a worsening of aneurysm occlusion between WEB treatment baseline and angiographic follow-up due to "compression" of the device. We utilized computational fluid dynamics (CFD) in order to determine whether the underlying mechanism of this worsening is flow related. We included data from all consecutive patients treated in our institution with a WEB for unruptured aneurysms located either at the middle cerebral artery or basilar tip. The CFD study was performed using pre-operative 3D rotational angiography. From digital subtraction follow-up angiographies patients were dichotomized into two groups: one with WEB "compression" and one without. We performed statistical analyses to determine a potential correlation between WEB compression and CFD inflow ratio. Between July 2012 and June 2015, a total of 22 unruptured middle cerebral artery or basilar tip aneurysms were treated with a WEB device in our department. Three patients were excluded from the analysis and the mean follow-up period was 17months. Eleven WEBs presented "compression" during follow-up. Interestingly, device "compression" was statistically correlated to the CFD inflow ratio (P=0.018), although not to aneurysm volume, aspect ratio or neck size. The mechanisms underlying the worsening of aneurysm occlusion in WEB-treated patients due to device compression are most likely complex as well as multifactorial. However, it is apparent from our pilot study that a high arterial inflow is, at least, partially involved. Further theoretical and animal research studies are needed to increase our understanding of this phenomenon. Copyright © 2017 Elsevier Masson SAS. All rights reserved.
International Nuclear Information System (INIS)
Ikeda, K.; Hoshi, M.
2001-01-01
Mitsubishi applied the Computational Fluid Dynamics (CFD) evaluation method for designing of the new lower pressure loss and higher DNB performance grid spacer. Reduction of pressure loss of the grid has been estimated by CFD. Also, CFD has been developed as a design tool to predict the coolant mixing ability of vane structures, that is to compare the relative peak spot temperatures around fuel rods at the same heat flux condition. These evaluations have been reflected to the new grid spacer design. The prototype grid was manufactured and some flow tests were performed to examine the thermal hydraulic performance, which were predicted by CFD. The experimental data of pressure loss was in good agreement with CFD prediction. The CFD prediction of flow behaviors at downstream of the mixing vanes was verified by detail cross-flow measurements at rod gaps by the rod LDV system. It is concluded that the applicability of the CFD evaluation method for the thermal hydraulic design of the grid is confirmed. (authors)
Perspectives on CFD analysis in nuclear reactor regulation
Energy Technology Data Exchange (ETDEWEB)
Boyd, Christopher, E-mail: christopher.boyd@nrc.gov
2016-04-01
The U.S. Nuclear Regulatory Commission is tasked with ensuring that the commercial use of nuclear materials in the United States is safe. This includes the review and evaluation of submitted analyses that support the safety justification for specific reactor-system components or scenarios. Typically these analyses involve the use of codes that have a proven history of validation and acceptance for the specific application of interest. The use of computational fluid dynamics (CFD) has not been as widespread in regulatory activities and the experience level with acceptance is more limited. The ever-increasing capacity of computers, along with the growing number of capable analysts, ensures us that CFD applications will continue to grow in usage for nuclear safety analysis. The challenge ahead is to ensure that these tools are properly validated and applied in order to build up the necessary evidence for more common acceptance in regulatory processes. The challenges include a continuation of the development and maintenance of best-practice guidance, development of problem-specific CFD-grade benchmark studies, the application of verification and validation techniques, and the development of practical treatments for uncertainties and scaling. Through these efforts, it is anticipated that CFD methods will continue to gain acceptance for use in nuclear reactor safety applications.
Coeficiente de transferência de carga nas fundações de silos verticais cilíndricos
Directory of Open Access Journals (Sweden)
Marivone Z. Fank
2015-09-01
Full Text Available RESUMOO dimensionamento das estruturas armazenadoras de grãos carece de uma norma brasileira que prescreva sobre seus projetos e ações; contudo, existem muitas lacunas no estado atual do conhecimento sendo imprescindíveis pesquisas adicionais sobre o tema. Com o objetivo de determinar a distribuição das cargas nas fundações dos silos foram instrumentadas, por meio de células de carga, quatro estacas localizadas sob o anel de um silo protótipo. O experimento ocorreu durante o período de agosto a dezembro de 2009 em Palotina, PR. As leituras das células foram realizadas por sistema automático de aquisição de dados durante o carregamento de grãos de milho e, a partir dos resultados, pode-se destacar um coeficiente de transferência médio de 0,30 para o anel até o carregamento de 44% do silo, a partir do qual ocorreu um incremento na taxa de transferência. As cargas máximas atuantes nas estacas instrumentadas foram de 800, 845, 520 e 600 kN, correspondentes a coeficientes de transferência de 0,48; 0,51; 0,31 e 0,36, respectivamente. Assim, o coeficiente regionalmente adotado de 0,30 para o dimensionamento das fundações do anel está subestimado fazendo-se necessária uma análise mais criteriosa nas taxas de transferência.
Investigation on a coupled CFD/DSMC method for continuum-rarefied flows
Tang, Zhenyu; He, Bijiao; Cai, Guobiao
2012-11-01
The purpose of the present work is to investigate the coupled CFD/DSMC method using the existing CFD and DSMC codes developed by the authors. The interface between the continuum and particle regions is determined by the gradient-length local Knudsen number. A coupling scheme combining both state-based and flux-based coupling methods is proposed in the current study. Overlapping grids are established between the different grid systems of CFD and DSMC codes. A hypersonic flow over a 2D cylinder has been simulated using the present coupled method. Comparison has been made between the results obtained from both methods, which shows that the coupled CFD/DSMC method can achieve the same precision as the pure DSMC method and obtain higher computational efficiency.
Wind Loads on Ships and Offshore Structures Estimated by CFD
DEFF Research Database (Denmark)
Aage, Christian; Hvid, S.L.; Hughes, P.H.
1997-01-01
Wind loads on ships and offshore structures could until recently be determined only by model tests, or by statistical methods based on model tests. By the development of Computational Fluid Dynamics or CFD there is now a realistic computational alternative available. In this paper, wind loads...... on a seagoing ferry and on a semisubmersible offshore platform have been estimated by CFD. The results have been compared with wind tunnel model tests and, for the ferry, a few full-scale measurements, and good agreement is obtained. The CFD method offers the possibility of a computational estimate of scale...... effects related to wind tunnel model testing. An example of such an estimate on the ferry is discussed. Due to the time involved in generating the computational mesh and in computing the solution, the CFD method is not at the moment economically competitive to routine wind tunnel model testing....
Cross cutting CFD support to innovative reactor design
International Nuclear Information System (INIS)
Roelofs, Ferry
2009-01-01
Several innovative technologies are under consideration in the world for nuclear energy production. The considered reactor systems apply either gas, sodium, lead, lead-bismuth, supercritical water, or molten salt as coolant. Therefore, methods shall be developed to determine the viability of such systems, but also to support the design of these innovative reactor systems. Computational Fluid Dynamics (CFD) is becoming more and more integrated in the daily practice of thermal-hydraulics researchers and designers. Therefore, it is very important to develop modelling approaches for the application of CFD to the specific requirements for innovative reactors. As many of these innovative reactor designs under consideration are operated using other coolants than water, one has to be careful in adopting methods which are developed for water as a coolant. Cross-cutting CFD challenges, methods and applications are presented for innovative reactors. (author)
Park, Michael A.; Krakos, Joshua A.; Michal, Todd; Loseille, Adrien; Alonso, Juan J.
2016-01-01
Unstructured grid adaptation is a powerful tool to control discretization error for Computational Fluid Dynamics (CFD). It has enabled key increases in the accuracy, automation, and capacity of some fluid simulation applications. Slotnick et al. provides a number of case studies in the CFD Vision 2030 Study: A Path to Revolutionary Computational Aerosciences to illustrate the current state of CFD capability and capacity. The authors forecast the potential impact of emerging High Performance Computing (HPC) environments forecast in the year 2030 and identify that mesh generation and adaptivity continue to be significant bottlenecks in the CFD work flow. These bottlenecks may persist because very little government investment has been targeted in these areas. To motivate investment, the impacts of improved grid adaptation technologies are identified. The CFD Vision 2030 Study roadmap and anticipated capabilities in complementary disciplines are quoted to provide context for the progress made in grid adaptation in the past fifteen years, current status, and a forecast for the next fifteen years with recommended investments. These investments are specific to mesh adaptation and impact other aspects of the CFD process. Finally, a strategy is identified to diffuse grid adaptation technology into production CFD work flows.
Enhancement of CFD validation exercise along the roof profile of a low-rise building
Deraman, S. N. C.; Majid, T. A.; Zaini, S. S.; Yahya, W. N. W.; Abdullah, J.; Ismail, M. A.
2018-04-01
The aim of this study is to enhance the validation of CFD exercise along the roof profile of a low-rise building. An isolated gabled-roof house having 26.6° roof pitch was simulated to obtain the pressure coefficient around the house. Validation of CFD analysis with experimental data requires many input parameters. This study performed CFD simulation based on the data from a previous study. Where the input parameters were not clearly stated, new input parameters were established from the open literatures. The numerical simulations were performed in FLUENT 14.0 by applying the Computational Fluid Dynamics (CFD) approach based on steady RANS equation together with RNG k-ɛ model. Hence, the result from CFD was analysed by using quantitative test (statistical analysis) and compared with CFD results from the previous study. The statistical analysis results from ANOVA test and error measure showed that the CFD results from the current study produced good agreement and exhibited the closest error compared to the previous study. All the input data used in this study can be extended to other types of CFD simulation involving wind flow over an isolated single storey house.
Social Change of Bajo Tribe Society in Karimunjawa: From "Sea Tribe" to "Land Tribe"
Directory of Open Access Journals (Sweden)
Titiek Suliyati
2017-12-01
The result of the research shows that there is a social change in Bajo society living permanently in Karimunjawa that is, the change of daily behavior in the society, social interaction with other tribes, values held by the society and social institution, structure and social classes. Social change occurring to Bajo society in Karimunjawa brings positive influences. The social changes among others are awareness towards the importance of education, Bajo society has new jobs other than fisherman, the increase of income, living standard, also modernization in fisheries system. The negative impact as a consequence of the social changes is faded culture, changes in life orientation and views of life, and consumerism in the society.
New CFD tools to evaluate nasal airflow.
Burgos, M A; Sanmiguel-Rojas, E; Del Pino, C; Sevilla-García, M A; Esteban-Ortega, F
2017-08-01
Computational fluid dynamics (CFD) is a mathematical tool to analyse airflow. As currently CFD is not a usual tool for rhinologists, a group of engineers in collaboration with experts in Rhinology have developed a very intuitive CFD software. The program MECOMLAND ® only required snapshots from the patient's cross-sectional (tomographic) images, being the output those results originated by CFD, such as airflow distributions, velocity profiles, pressure, temperature, or wall shear stress. This is useful complementary information to cover diagnosis, prognosis, or follow-up of nasal pathologies based on quantitative magnitudes linked to airflow. In addition, the user-friendly environment NOSELAND ® helps the medical assessment significantly in the post-processing phase with dynamic reports using a 3D endoscopic view. Specialists in Rhinology have been asked for a more intuitive, simple, powerful CFD software to offer more quality and precision in their work to evaluate the nasal airflow. We present MECOMLAND ® and NOSELAND ® which have all the expected characteristics to fulfil this demand and offer a proper assessment with the maximum of quality plus safety for the patient. These programs represent a non-invasive, low-cost (as the CT scan is already performed in every patient) alternative for the functional study of the difficult rhinologic case. To validate the software, we studied two groups of patients from the Ear Nose Throat clinic, a first group with normal noses and a second group presenting septal deviations. Wall shear stresses are lower in the cases of normal noses in comparison with those for septal deviation. Besides, velocity field distributions, pressure drop between nasopharynx and the ambient, and flow rates in each nostril were different among the nasal cavities in the two groups. These software modules open up a promising future to simulate the nasal airflow behaviour in virtual surgery intervention scenarios under different pressure or
CFD Modeling and Simulation in Materials Processing 2018
Nastac, Laurentiu; Pericleous, Koulis; Sabau, Adrian S.; Zhang, Lifeng; Thomas, Brian G.
2018-01-01
This book contains the proceedings of the symposium “CFD Modeling and Simulation in Materials Processing” held at the TMS 2018 Annual Meeting & Exhibition in Phoenix, Arizona, USA, March 11–15, 2018. This symposium dealt with computational fluid dynamics (CFD) modeling and simulation of engineering processes. The papers published in this book were requested from researchers and engineers involved in the modeling of multiscale and multiphase phenomena in material processing systems. The sympos...
Directory of Open Access Journals (Sweden)
Santiago Giraldo
2008-12-01
aire sobre la superficie del terreno (Dominio CFD. Datos obtenidos de la misión satelital Landsat fueron utilizados para establecer temperaturas sobre el terreno para distintos materiales y fue mapeada sobre el terreno utilizando técnicas de interpolación. Las ecuaciones de Navier–Stokes fueron solucionadas para modelos de fenómenos de convección natural con efectos de flujo turbulento de fluidos compresibles, tomando en cuenta efectos convectivos y de transferencia de calor. La simulación incluye convección y condiciones de turbulencia bajo el modelo k–epsilon utilizando las instalaciones de computaci´on de alto desempeño de Westgrid (Western Canada Research Grid. Los resultados preliminares muestran distribuciones de viento comparables a las observadas en la región de baja altitud
Fernández Sierra, Carmen; Matzumura Kasano, Juan; Gutiérrez Crespo, Hugo; Zamudio Eslava, Luisa; Melgarejo García, Giannina
2017-01-01
Objetivo: Describir las secuelas del neurodesarrollo de los recién nacidos prematuros de extremadamente bajo peso y de muy bajo peso a los dos años de edad, egresados de la Unidad de Cuidados Intensivos Neonatales del Hospital Nacional Edgardo Rebagliati Martins. Materiales y métodos: Estudio descriptivo, retrospectivo, transversal en una población de 190 prematuros de extremadamente bajo peso y de muy bajo peso que nacieron durante enero 2009 a junio del 2014, egresados de la Unidad de Cuida...
Directory of Open Access Journals (Sweden)
Denise Elvira Pires de Pires
2012-03-01
Full Text Available Trata-se de uma revisão integrativa com objetivo de rastrear a produção científica acerca da influência da inovação tecnológica nas cargas de trabalho dos profissionais de saúde. Selecionou-se 57 publicações nas bases de interesse de 2004 a 2009. Predominaram as pesquisas de campo com abordagem qualitativa, realizadas em hospitais. Nenhum estudo teve por objetivo relacionar inovação tecnológica e cargas de trabalho. Nos estudos sobre inovação tecnológica destacaram-se publicações sobre tecnologias de informação e comunicação e novas formas de organização do trabalho; no tema cargas de trabalho predominaram estudos sobre condições promotoras de estresse e Burnout. Os achados mostraram que as inovações influenciam as cargas de trabalho de modo ambíguo, podendo aumentá-las ou diminuí-las.Se trata de una revisión integradora con el fin de rastrear la literatura científica sobre la influencia de la innovación tecnológica en la carga de trabajo de los profesionales de la salud. Fueron seleccionados 57 artículos en las bases de interés 2004 y 2009. Predominaron investigaciones de campo con un enfoque cualitativo, llevado a cabo en hospitales. Ningún estudio buscó relacionar la innovación tecnológica y las cargas de trabajo. En estudios de innovación tecnológica se destacaron las publicaciones sobre tecnologías de la información y comunicación y nuevas formas de organización del trabajo, los estudios de la carga de trabajo promueve estudios sobre el estrés y el Burnout. Los resultados mostraron que las innovaciones afectan a las cargas de trabajo de forma ambigua y puede aumentarlos o reducirlos.This is an integrative review with the aim of tracing the scientific production concerning the influence of technological innovation in health care professionals' workloads. Fifty-seven (57 publications presented from 2004 to 2009 were selected from the LILACS and PubMed databases. In the selected studies field
CFD computations of the second round of MEXICO rotor measurements
DEFF Research Database (Denmark)
Sørensen, Niels N.; Zahle, Frederik; Boorsma, K.
2016-01-01
A comparison, between selected wind tunnel data from the NEW MEXICO measuring campaign and CFD computations are shown. The present work, documents that a state of the art CFD code, including a laminar turbulent transition model, can provide good agreement with experimental data. Good agreement...
Verification of supersonic and hypersonic semi-empirical predictions using CFD
International Nuclear Information System (INIS)
McIlwain, S.; Khalid, M.
2004-01-01
CFD was used to verify the accuracy of the axial force, normal force, and pitching moment predictions of two semi-empirical codes. This analysis considered the flow around the forebody of four different aerodynamic shapes. These included geometries with equal-volume straight or tapered bodies, with either standard or double-angle nose cones. The flow was tested at freestream Mach numbers of M = 1.5, 4.0, and 7.0. The CFD results gave the expected flow pressure contours for each geometry. The geometries with straight bodies produced larger axial forces, smaller normal forces, and larger pitching moments compared to the geometries with tapered bodies. The double-angle nose cones introduced a shock into the flow, but affected the straight-body geometries more than the tapered-body geometries. Both semi-empirical codes predicted axial forces that were consistent with the CFD data. The agreement between the normal forces and pitching moments was not as good, particularly for the straight-body geometries. But even though the semi-empirical results were not exactly the same as the CFD data, the semi-empirical codes provided rough estimates of the aerodynamic parameters in a fraction of the time required to perform a CFD analysis. (author)
On application of CFD codes to problems of nuclear reactor safety
International Nuclear Information System (INIS)
Muehlbauer, Petr
2005-01-01
The 'Exploratory Meeting of Experts to Define an Action Plan on the Application of Computational Fluid Dynamics (CFD) Codes to Nuclear Reactor Safety Problems' held in May 2002 at Aix-en-Province, France, recommended formation of writing groups to report the need of guidelines for use and assessment of CFD in single-phase nuclear reactor safety problems, and on recommended extensions to CFD codes to meet the needs of two-phase problems in nuclear reactor safety. This recommendations was supported also by Working Group on the Analysis and Management of Accidents and led to formation oaf three Writing Groups. The first writing Group prepared a summary of existing best practice guidelines for single phase CFD analysis and made a recommendation on the need for nuclear reactor safety specific guidelines. The second Writing Group selected those nuclear reactor safety applications for which understanding requires or is significantly enhanced by single-phase CFD analysis, and proposed a methodology for establishing assesment matrices relevant to nuclear reactor safety applications. The third writing group performed a classification of nuclear reactor safety problems where extension of CFD to two-phase flow may bring real benefit, a classification of different modeling approaches, and specification and analysis of needs in terms of physical and numerical assessments. This presentation provides a review of these activities with the most important conclusions and recommendations (Authors)
Results of a CFD benchmark for wind loads on a high-rise building
Bronkhorst, A.J.; Bentum, C.A. van; Geurts, C.P.W.
2017-01-01
In recent years, the use of computational fluid dynamics (CFD) to evaluate flow fields has become more popular in various branches of industry. In building design, there is a similar trend towards the increasing use of CFD. There are several guidelines for CFD analysis of flows in the urban
CFD applications in hypersonic flight
Edwards, T. A.
1992-01-01
Design studies are underway for a variety of hypersonic flight vehicles. The National Aero-Space Plane will provide a reusable, single-stage-to-orbit capability for routine access to low earth orbit. Flight-capable satellites will dip into the atmosphere to maneuver to new orbits, while planetary probes will decelerate at their destination by atmospheric aerobraking. To supplement limited experimental capabilities in the hypersonic regime, CFD is being used to analyze the flow about these configurations. The governing equations include fluid dynamic as well as chemical species equations, which are solved with robust upwind differencing schemes. Examples of CFD applications to hypersonic vehicles suggest an important role this technology will play in the development of future aerospace systems. The computational resources needed to obtain solutions are large, but various strategies are being exploited to reduce the time required for complete vehicle simulations.
The difference between traditional experiments and CFD validation benchmark experiments
Energy Technology Data Exchange (ETDEWEB)
Smith, Barton L., E-mail: barton.smith@usu.edu
2017-02-15
Computation Fluid Dynamics provides attractive features for design, and perhaps licensing, of nuclear power plants. The most important of these features is low cost compared to experiments. However, uncertainty of CFD calculations must accompany these calculations in order for the results to be useful for important decision making. In order to properly assess the uncertainty of a CFD calculation, it must be “validated” against experimental data. Unfortunately, traditional “discovery” experiments are normally ill-suited to provide all of the information necessary for the validation exercise. Traditionally, experiments are performed to discover new physics, determine model parameters, or to test designs. This article will describe a new type of experiment; one that is designed and carried out with the specific purpose of providing Computational Fluid Dynamics (CFD) validation benchmark data. We will demonstrate that the goals of traditional experiments and validation experiments are often in conflict, making use of traditional experimental results problematic and leading directly to larger predictive uncertainty of the CFD model.
The difference between traditional experiments and CFD validation benchmark experiments
International Nuclear Information System (INIS)
Smith, Barton L.
2017-01-01
Computation Fluid Dynamics provides attractive features for design, and perhaps licensing, of nuclear power plants. The most important of these features is low cost compared to experiments. However, uncertainty of CFD calculations must accompany these calculations in order for the results to be useful for important decision making. In order to properly assess the uncertainty of a CFD calculation, it must be “validated” against experimental data. Unfortunately, traditional “discovery” experiments are normally ill-suited to provide all of the information necessary for the validation exercise. Traditionally, experiments are performed to discover new physics, determine model parameters, or to test designs. This article will describe a new type of experiment; one that is designed and carried out with the specific purpose of providing Computational Fluid Dynamics (CFD) validation benchmark data. We will demonstrate that the goals of traditional experiments and validation experiments are often in conflict, making use of traditional experimental results problematic and leading directly to larger predictive uncertainty of the CFD model.
Prediction of ash deposition using CFD simulation combined to thermodynamic calculation
Energy Technology Data Exchange (ETDEWEB)
Takeshi Muratani; Takashi Hongo [UBE Industries, Ltd., Yamaguchi (Japan). Coal Department, Energy and Environment Division
2007-07-01
This study focused on the advanced ash deposition prediction using computational fluid dynamics (CFD) analysis combined to thermodynamic calculation, considering both combustion characteristics and ash fusibility. Combustion field in pulverised coal-fired boiler was calculated through the normal CFD process. As the post process of combustion calculation, ash particles were injected into the combustion field to calculate ash deposition by CFD, in which particle sticking sub-program was newly employed. In this post process, ash deposition condition for CFD calculation was defined with the ash fusibility data obtained from thermodynamic analysis. These results of ash deposition on the furnace wall showed good agreement with the plant observation. Furthermore, in order to improve the plant operation, some virtual cases were simulated, which might reduce ash deposition. 7 refs., 14 figs., 6 tabs.
Arias-Rojas, Mauricio; Barrera-Ortiz, Lucy; Mabel-Carrillo, Gloria; Chaparro-Díaz, Lorena; Sánchez-Herrera, Beatriz; Vargas-Rosero, Elizabeth
2014-01-01
Antecedentes.En situaciones de enfermedad crónica, la familia es el principal apoyo para las personas enfermas. Si bien el sistema de salud no siempre reconoce a los cuidadores familiares, ellos dedican la mayor parte del tiempo al cuidado de sus seres queridos y se infiere que, en las regiones de frontera, debe ser más complejo asumir esta labor, lo cual supone una mayor carga para ellos. Objetivo. Comparar las características sociodemográficas y el nivel de carga percibido por los cuidadore...
International Nuclear Information System (INIS)
Mirza, S.A.
1999-01-01
In the present study, a two-dimensional computer code has been developed in FORTRAN using CFD technique, which is basically a numerical scheme. This computer code solves the Navier Stokes equations and continuity equation to find out the velocity and pressure fields within a given domain. This analysis has been done for the developed within a square cavity driven by the upper wall which has become a bench mark for testing and comparing the newly developed numerical schemes. Before to handle this task, different one-dimensional cases have been studied by CFD technique and their FORTRAN programs written. The cases studied are Couette flow, Poiseuille flow with and without using symmetric boundary condition. Finally a comparison between CFD results and analytical results has also been made. For the cavity flow the results from the developed code have been obtained for different Reynolds numbers which are finally presented in the form of velocity vectors. The comparison of the developed code results have been made with the results obtained from the share ware version of a commercially available code for Reynolds number of 10.0. The disagreement in the results quantitatively and qualitatively at some grid points of the calculation domain have been discussed and future recommendations in this regard have also been made. (author)
Examples of using CFD for wind turbine aerodynamics
Energy Technology Data Exchange (ETDEWEB)
Hansen, M.O.L.; Soerensen, J.N. [Technical Univ. of Denmark, Dept. of Energy Engineering (Denmark); Soerensen, N.N. [Risoe National Lab., Test Station for Wind Turbines (Denmark)
1997-12-31
Overall it is concluded that in order to improve the results from CFD (Computational Fluid Dynamics) for wind turbine aerodynamics characterized by: high angles of attack; thick airfoils; 3-D effects; instationary effects. Extreme care must be put on turbulence and transition models, and fine grids are necessary especially at the suction peak. If these precautions are taken CFD can be used as a tool for obtaining lift and drag coefficients for the BEM (Blade Element Momentum) model. (au)
Directory of Open Access Journals (Sweden)
Edgar A. Pinzón
2016-05-01
Full Text Available Resumen Objetivo: establecer la relación entre la carga del cuidado y la calidad de vida en cuidadores familiares de personas con enfermedades respiratorias crónicas. Metodología: estudio de abordaje cuantitativo descriptivo, de correlación, y corte transversal. Participaron 55 cuidadores familiares que asisten a una institución de tercer nivel de atención en salud de la ciudad de Bucaramanga. Se utilizaron los instrumentos: encuesta de caracterización del cuidador familiar de persona con enfermedad crónica, calidad de vida versión familiar de persona con enfermedad crónica y Carga del cuidado de Zarit. El análisis se realizó mediante estadística descriptiva con medidas de tendencia central y de dispersión y la determinación del coeficiente de correlación de Spearman Resultados: los cuidadores familiares son en su mayoría mujeres, de estratos socioeconómicos bajos, ocupación hogar, una mediana de 18 horas día a la asistencia y cuidado; presentan una calidad de vida global percibida media. En cuanto a la carga del cuidado el 23,7% de los cuidadores presenta una sobrecarga severa, el 27,3% sobrecarga leve y el 49%, no presentan sobrecarga de acuerdo con la clasificación establecida por Zarit. El coeficiente de correlación de Spearman obtenido fue de -0,783 estadísticamente significativo (p=0,00 Conclusión: existe una correlación inversa entre la calidad de vida y la carga de cuidado de los cuidadores familiares de personas con enfermedad respiratoria crónica. / Abstract Objective: to establish the relationship between the care burden and quality of life of family caregivers of patients with chronic respiratory diseases. Methodology: a quantitative, descriptive, correlation, and cross sectional study performed with 55 family caregivers attending a tertiary health care institution in the city of Bucaramanga. The following instruments were used: characterization survey of the family caregivers of people with chronic
CFD analysis for spacer grid mixing vane design
International Nuclear Information System (INIS)
Park, Sung-Kew; Kim, Kang-Hoon; Park, Eung-Jun; Jung, Yil-Sup; Suh, Jung-Min; Jeong, Ji-Hun
2008-01-01
A computational fluid dynamics (CFD) analysis for a rod bundle with the larger scale model (6x6 array model) has been performed to develop the base shape of mixing vane in accordance with the hydraulic and thermal performance. Explanatory parameters are span pressure drop and span average heat transfer coefficient. The concern related to hot spot is also considered as a subsidiary criterion. Of the several candidates, the final candidate was determined by using the CFD analysis code, STAR-CD. And then, the optimization for it was performed using the response surface method (RSM) that the proper tolerance was considered under the two acceptance criteria such as lower span pressure drop while maintaining the span average heat transfer coefficient with respect to the current shape. The optimized mixing vane shape was verified by the CFD analysis including the effects of allowable tolerance. (author)
Condiciones de trabajo materno y bajo peso al nacer en la Ciudad de México
Directory of Open Access Journals (Sweden)
CERÓN-MIRELES PRUDENCIA
1997-01-01
Full Text Available Objetivo. Estudiar la asociación entre condiciones de trabajo materno y bajo peso al nacer en la Ciudad de México. Material y métodos. Se encuestaron 2 623 trabajadoras que atendieron sus partos en tres grandes hospitales de la Ciudad de México en 1992. Se obtuvo información sobre los principales factores biológicos y sociales que se asocian al bajo peso al nacer; asimismo, se determinó el estrés ocupacional utilizando el instrumento desarrollado por Karasek. Se utilizaron modelos de regresión logística para evaluar la relación de las condiciones de trabajo con el bajo peso al nacer, controlando por variables confusoras. Resultados. El bajo peso al nacer fue más alto en trabajadoras con jornadas mayores a 50 horas semanales (RM= 1.6; IC= 1.17, 2.28 y con conflictos laborales (RM= 1.5; IC= 1.0, 2.25. La falta de apoyo social tangible fue identificado como un factor de riesgo de bajo peso al nacer (RM= 1.7; IC= 1.20, 2.33. Las medidas preventivas laborales como el cambio de tareas, disminución de la jornada y las salidas por enfermedad no mostraron un efecto benéfico en el peso al nacer, a excepción de la licencia de maternidad; las madres que no la tuvieron mostraron una probabilidad 2.2 veces mayor para bajo peso al nacer (IC= 1.66, 2.93. Conclusiones. Estos hallazgos resaltan la importancia de identificar los factores de riesgo ocupacional en el embarazo..
CFD modeling of fouling in crude oil pre-heaters
International Nuclear Information System (INIS)
Bayat, Mahmoud; Aminian, Javad; Bazmi, Mansour; Shahhosseini, Shahrokh; Sharifi, Khashayar
2012-01-01
Highlights: ► A conceptual CFD-based model to predict fouling in industrial crude oil pre-heaters. ► Tracing fouling formation in the induction and developing continuation periods. ► Effect of chemical components, shell-side HTC and turbulent flow on the fouling rate. - Abstract: In this study, a conceptual procedure based on the computational fluid dynamic (CFD) technique has been developed to predict fouling rate in an industrial crude oil pre-heater. According to the developed CFD concept crude oil was assumed to be composed of three pseudo-components comprising of petroleum, asphaltene and salt. The binary diffusion coefficients were appropriately categorized into five different groups. The species transport model was applied to simulate the mixing and transport of chemical species. The possibility of adherence of reaction products to the wall was taken into account by applying a high viscosity for the products in competition with the shear stress on the wall. Results showed a reasonable agreement between the model predictions and the plant data. The CFD model could be applied to new operating conditions to investigate the details of the crude oil fouling in the industrial pre-heaters.
Directory of Open Access Journals (Sweden)
García Prieto, M. A.
1999-04-01
Full Text Available A characteristic of the glass is its fragility and the scatter of the experimental mechanical strength due to the presence of defects that appear in the process of manufacturing or handling. Accordingly, investigations on this material were priorly conducted to improve the processes of manufacturing and to establish design methodologies based on probabilistic approaches. The influence of mode II of loading was traditionally ignored or considered as ratio of mode II. Recent studies have shown that when a shear-loaded crack becomes unstable a new compressive stress concentration field builds up in the notch formed between the original crack and the branch crack. This stress field affects the energy balance and also the beginning of crack extension. A procedure to design glass elements was developed jointly with CIDA of Cristalería Española, S.A. The aim of this work is to improve the model by the consideration of a mixed mode loading and its experimental contrast.
Una de las características del vidrio es su fragilidad y la gran dispersión de sus valores de resistencia mecánica, motivado fundamentalmente por la presencia de defectos procedentes de su fabricación o de su manipulación. Como consecuencia, las investigaciones en este material se han dirigido preferentemente a la mejora de los procesos de fabricación y al establecimiento de metodologías de diseño basadas en modelos probabilísticos. Tradicionalmente, en el análisis de la rotura se ha despreciado la influencia del modo II o se ha representado como un porcentaje del modo I. Recientes estudios demuestran la aparición de un nuevo campo de tensiones de compresión cuando una fisura crece bajo una carga en modo II puro situado en el codo que se forma entre la fisura original y su ramificación. Este campo de compresión influye en el equilibrio energético y, en consecuencia, en la predicción de la rotura. En colaboración con el CIDA de Cristalería Española, S.A. se ha
Coupled CFD - system-code simulation of a gas cooled reactor
International Nuclear Information System (INIS)
Yan, Yizhou; Rizwan-uddin
2011-01-01
A generic coupled CFD - system-code thermal hydraulic simulation approach was developed based on FLUENT and RELAP-3D, and applied to LWRs. The flexibility of the coupling methodology enables its application to advanced nuclear energy systems. Gas Turbine - Modular Helium Reactor (GT-MHR) is a Gen IV reactor design which can benefit from this innovative coupled simulation approach. Mixing in the lower plenum of the GT-MHR is investigated here using the CFD - system-code coupled simulation tool. Results of coupled simulations are presented and discussed. The potential of the coupled CFD - system-code approach for next generation of nuclear power plants is demonstrated. (author)
Microbiological corrosion in low carbon steels; Corrosion microbiologica en aceros de bajo carbono
Energy Technology Data Exchange (ETDEWEB)
Medina-Custodio, O; Ortiz-Prado, A; Jacobo-Armendariz, V. H; Schouwenaars-Franssens, R [Universidad Nacional Autonoma de Mexico, Mexico, D.F. (Mexico)]. E-mail: medina_1979@yahoo.com; armandoo@servidor.unam.mx; vjacobo@dgapa.unam.mx; raf_schouweenaars@yahoo.com
2009-01-15
The Microbiologically Induced Corrosion affects several industries, such as oil industry where it is estimated that 20% to 30% pipes failures are related with microorganism. The chemical reactions generate ions transfer, this validate the use of electrochemical technique for its analysis. Coupons submerged in a nutritional medium with presence and absence of three different microorganisms during two periods, 48 hours and 28 days were studied. Polarization resistance (Rp) and Electrochemical Impedance Spectroscopy (EIS) techniques were applied to determine the corrosively of the systems. The results show a greater corrosive effect of abiotic systems, this indicates a microorganisms protection effect to the metal, opposite to the first hypothesis. This result was ratified observing surface coupons by using Scanning Electron Microscopy (SEM) technique. A possible mechanism based on Evans - Tafel graph is proposed to explain inhibitor microorganism effect. [Spanish] La corrosion microbiologica es un tipo comun de deterioro que afecta diversas industrias, una de ellas es la petrolera en la que se estiman que el 20% o 30% de fallas en las tuberias de trasporte de hidrocarburos es favorecida por microorganismos. Las reacciones quimicas que sustentan estos, generan transferencia de iones, lo que justifica el empleo de tecnicas electroquimicas para su analisis. En este trabajo, se estudiaron probetas de acero de bajo carbono SAE 1018, sumergidas en un medio nutritivo rico en cloruros en presencia y ausencia de tres diferentes cargas microbianas, en tiempos de exposicion de 48 horas y 28 dias. Se realizaron ensayos de resistencia a la polarizacion (Rp) y espectroscopia de impedancia electroquimica (EIS) para determinar el efecto corrosivo de los diferentes sistemas. Los resultados muestran que el medio abiotico causa el mayor efecto corrosivo, lo que indica un efecto protector de los microorganismos al metal contradiciendo la hipotesis inicialmente propuesta. La observacion
Modelling of Air Flow trough a Slatted Floor by CFD
DEFF Research Database (Denmark)
Svidt, Kjeld; Bjerg, Bjarne; Morsing, Svend
In this paper two different CFD-approaches are investigated to model the airflow through a slatted floor. Experiments are carried out in a full-scale test room. The computer simulations are carried out with the CFD-code FLOVENT, which solves the time-averaged Navier-Stokes equations by use of the k...
CFD Simulations of Contaminant Transport between two Breathing Persons
DEFF Research Database (Denmark)
Bjørn, Erik; Nielsen, Peter V.
Experiments have shown that exhalation from one person is able to penetrate the breathing zone of another person at a distance. Computational Fluid Dynamics (CFD) is used to investigate the dependency of the personal exposure on some physical parameters, namely: Pulmonary ventilation rate......, convective heat output, exhalation temperature, and crosssectional exhalation area. Full-scale experimental results are used to calibrate/validate the CFD model....
Capacidade de Carga Turística: Um Estudo no Caminhos Rurais de Porto Alegre, RS
Directory of Open Access Journals (Sweden)
Juliane Magagnin Da Soller
2013-10-01
Full Text Available Nesse artigo, apresenta-se o contexto do turismo de base comunitária, além de breve histórico e discussão acerca do conceito e da metodologia da Capacidade de Carga Turística, assim como a adaptação da metodologia para estudo aqui relatado. Descreve-se o estudo realizado para determinar a Capacidade de Carga Turística, tendo por amostra as propriedades rurais partícipes da Associação Porto Alegre Rural (POA RURAL, mais especialmente do roteiro Caminhos Rurais de Porto Alegre, no estado do Rio Grande do Sul. Propôs-se adaptar a para o local a metodologia de cálculo de Capacidade de Carga Turística a partir de Cifuentes (1992; et al 1996, considerando suas particularidades, principalmente aquelas que dizem respeito a saúde e ao bem-estar das famílias que recebem os visitantes e aos impactos ambientais causados pelas construções de infraestrutura turística. A Capacidade de Carga Turística é uma metodologia desenvolvida para áreas preservadas de uso público. Assim, não costuma dar enfoque às questões referentes à comunidade local e aos resíduos gerados pelas instalações e pelos serviços prestados no Turismo. Tourist Carrying Capacity: A study in the Caminhos Rurais de Porto Alegre, RS - This paper presents the community based tourism and a brief history, concept and methodology of Tourist Carrying Capacity, and the adaptation of that methodology to the present case. The paper presents the study to determine the Tourist Carrying Capacity in rural proprieties that currently constitute the Porto Alegre Rural Association (RURAL POA, the tourist destination Caminhos Rurais de Porto Alegre, Rio Grande do Sul. The research proposes to adapt the methodology of Tourist Carrying Capacity from Cifuentes (1992, et al 1996, to the Caminhos Rurais, considering its particularities, especially those relate to health and well-being of families who receives visitors, and the environmental impacts caused by the construction of
CFD Analysis on the Periodic Element of a Printed Circuit Heat Exchanger
International Nuclear Information System (INIS)
Tak, Nam-il; Kim, Min-Hwan; Lee, Won-Jae
2007-01-01
A typical printed circuit heat exchanger (PCHE) is composed of a large number of flow channels with lateral corrugations. In an effort to investigate fundamental thermo-fluid characteristics of a PCHE with corrugated channels, computational fluid dynamics (CFD) analyses were previously made in. One pair of flow channels (i.e., cold and hot channels) with the entire flow path was considered for the computational domain in the previous studies. Although only one pair of flow channels with coarse meshes was used, computational loads were found to be very high to simulate the entire flow path of the PCHE. Fortunately a recent study has shown that a simplified CFD methodology with a stream wise periodic assumption (called periodic CFD analysis) is feasible for a CFD evaluation of the thermo-fluid performance of compact heat exchangers. Since the periodic CFD analysis focuses on the periodic element of a flow channel, the required computing resources are dramatically reduced. In the present paper, the periodic CFD analysis has been applied to the periodic element of the PCHE. The results are compared with those of the full elements which have an entire flow path. Based on the periodic approach the effects of the corrugation parameters on the thermo-fluid performance of the PCHE are investigated
Possible User-Dependent CFD Predictions of Transitional Flow in Building Ventilation
DEFF Research Database (Denmark)
Peng, Lei; Nielsen, Peter Vilhelm; Wang, Xiaoxue
2016-01-01
A modified backward-facing step flow with a large expansion ratio of five (5) was modelled by 19 teams without benchmark solutions or experimental data for validation in an ISHVAC-COBEE July 2015 Tianjin Workshop, entitled as “to predict low turbulent flow”. Different computational fluid dynamics...... (CFD) codes/software, turbulence models, boundary conditions, numerical schemes and convergent criteria were adopted based on the own CFD experience of each participating team. The largest coefficient of variation is larger than 50% and the largest relative maximum difference of penetration length......, is shown to be still a very challenging task. This calls for a solid approach of validation and uncertainty assessment in CFD “experiments”. The users are recommended to follow an existing guideline of uncertainty assessment of CFD predictions to minimize the errors and uncertainties in the future....
Efecto de las cargas articulares sobre el flujo y pH salival
Castro, R.J.; Bravo, C.; Alcaino, V.; Giacaman, R.A.
2011-01-01
Una alteración del flujo salival es clave en el desarrollo de caries, enfermedad periodontal e infecciones oportunistas. El flujo salival está determinado por diversos estímulos que actúan sobre receptores de distinta naturaleza, entre ellos mecanoreceptores articulares. Algunos estudios demuestran que las cargas articulares actúan sobre estos receptores, modificando cualitativa y cuantitativamente la secreción salival. El objetivo de este estudio fue determinar si existe una relación entre l...
Control de balanceo de carga de un grupo de servidores de red
Talavera Foix , Miquel; Albea , Carolina
2014-01-01
National audience; Debido al incremento de servicios en Internet y del numero de usuarios, se ha multiplicado la demanda de prestaciones de los servidores web. Si se usa adecuadamente los "clusteres", se puede llegar a una potencia correcta de procesamiento que permita satisfacer los requerimientos. El equilibrado de carga, o "load balancing", permite crear una red robusta y efciente. En este trabajo se presenta una ley de control distribuido inspirada en la "teoria deconsenso". El bucle cerr...
CFD simulation on condensation inside a Hybrid SIT
Energy Technology Data Exchange (ETDEWEB)
Jeon, Byong Guk; Ryu, Sung Uk; Kim, Seok; Euh, Dong Jin [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)
2016-10-15
The concept of Hybrid Safety Injection Tank system (Hybrid SIT) was proposed by Korea Atomic Energy Research Institute (KAERI) aiming at Advanced Power Reactor Plus. The main advantage of the system is the ready injection of coolant into the reactor coolant system at high pressure. In this paper, a CFD simulation is conducted as a preliminary study. In Hybrid SITs, condensation inside the tank affects its pressure rise and injection time. In an attempt to explore the condensation in detail, we manufactured a dedicated experimental facility for visualization of condensation-induced thermal mixing and conducted a preliminary CFD simulation. Its condensation models were validated first and then computational domain was constructed. The water region was modeled as a solid for stable calculation. The CFD results gave less condensation and excessive pressurization because of lack of steam penetration into the water. In the future, the water region will be modeled as liquid using a VOF model.
Wood, William A.; Kleb, William L.; Tang, chun Y.; Palmer, Grant E.; Hyatt, Andrew J.; Wise, Adam J.; McCloud, Peter L.
2010-01-01
Surface temperature measurements from the STS-119 boundary-layer transition experiment on the space shuttle orbiter Discovery provide a rare opportunity to assess turbulent CFD models at hypersonic flight conditions. This flight data was acquired by on-board thermocouples and by infrared images taken off-board by the Hypersonic Thermodynamic Infrared Measurements (HYTHIRM) team, and is suitable for hypersonic CFD turbulence assessment between Mach 6 and 14. The primary assessment is for the Baldwin-Lomax and Cebeci-Smith algebraic turbulence models in the DPLR and LAURA CFD codes, respectively. A secondary assessment is made of the Shear-Stress Transport (SST) two-equation turbulence model in the DPLR code. Based upon surface temperature comparisons at eleven thermocouple locations, the algebraic-model turbulent CFD results average 4% lower than the measurements for Mach numbers less than 11. For Mach numbers greater than 11, the algebraic-model turbulent CFD results average 5% higher than the three available thermocouple measurements. Surface temperature predictions from the two SST cases were consistently 3 4% higher than the algebraic-model results. The thermocouple temperatures exhibit a change in trend with Mach number at about Mach 11; this trend is not reflected in the CFD results. Because the temperature trends from the turbulent CFD simulations and the flight data diverge above Mach 11, extrapolation of the turbulent CFD accuracy to higher Mach numbers is not recommended.
Directory of Open Access Journals (Sweden)
Manuel Gutiérrez Henríquez
Full Text Available RESUMEN Los trastornos músculo-esqueléticos (TMEs se encuentran entre los principales problemas de salud laboral en Chile, así como también a nivel internacional. En este sentido, los antecedentes epidemiológicos indican que uno de los potenciales agentes causales de TMEs corresponde al manejo manual de carga. Al respecto, la normativa chilena carece de métodos para evaluar riesgos de trastornos músculo-esqueléticos asociados a la manipulación de carga con una mano. Objetivo: Determinar la capacidad de elevación y descenso de carga con una mano en trabajadores de género masculino. Material y método: El estudio se efectuó en un centro hospitalario público y una industria metalúrgica de la Provincia de Concepción. Los trabajadores que participaron en el estudio efectuaban labores asociadas al manejo de manual de carga y/o pacientes. Para la determinación de peso máximo aceptable (PMA se aplicaron pruebas psicofísicas. Se estudiaron las tareas de elevaciones y descensos entre suelo y codo, así como entre codo y alcance vertical de brazo. Se evaluaron diferentes frecuencias de manipulación de carga, siendo éstas una elevación o descenso cada 10 segundos, 1 minuto, 30 minutos, 1 hora y 8 horas. Resultados: Para las tareas analizadas, se determinaron valores de PMA que protegen al 10%, 25%, 50%, 75% y 90% del grupo estudiado. Discusión: Al comparar los resultados obtenidos en el presente estudio con referencias bibliográficas de capacidad de manipulación de carga con dos manos, se verificó que el PMA determinado para una mano es menor entre un 55% a 69% que el registrado para dos manos. Se plantea la necesidad de efectuar estudios complementarios que permitan validar los resultados obtenidos, para avanzar en el desarrollo de métodos, criterios y normativa aplicable a tareas de elevación y descenso de carga con una mano.
Energy Technology Data Exchange (ETDEWEB)
Kaiser, R.; Olesen, M. [Zeuna Staerker GmbH und Co. KG (Germany)
2002-06-01
Under the pressure of ever shorter development times and high demands on exhaust systems in terms of exhaust counterpressure, acoustic and sensory aspects and exhaust purification, Zeuna Staerker started at an early stage to use advanced CFD methods in their product development process. The contribution investigates the effects of simplified assumptions of boundary conditions, using laser optical flow measurements on a turbocharger with a catalyst near the engine. [German] Immer kuerzer werdende Entwicklungszeiten und die hohen Anforderungen an Abgasanlagen hinsichtlich Abgasgegendruck, Akustik, Sensorik und Abgasreinigung fuehrten bei Zeuna Staerker schon fruehzeitig zur Etablierung ausgereifter CFD-Methoden im Produktentwicklungsprozess. Doch wie stark werden CFD-Berechnungen durch die aufgepraegten Randbedingungen beeinflusst, wenn diese nach Abgasturbolader oft vereinfacht angenommen werden muessen? Mit Hilfe laseroptischer Stroemungsmessungen an einem Abgasturbolader mit motornahem Katalysator wird dieser Frage nachgegangen. (orig.)
Síntesis y almacenamiento de carga de la nueva aleación polipirrol/poli(ácido maleico-olefina
Directory of Open Access Journals (Sweden)
D´eramo, F.
2000-06-01
Full Text Available The influence that the electrosynthesis conditions of the polypyrrole/poly(maleic acid-co-olefin blend have on the charge storage ability (amount of electrical charge stored (mC per unit mass (mg of electrogenerated polymer has been analysed. This is the initial step for the optimisation, pyrrole and poly (maleic acid-co-olefin concentrations and the polymerisation temperature have been the studied parameters. Optimising these ones, we could obtain materials with average storage charge of 120mc.mg-1.
Se ha analizado la influencia de diversas variables de síntesis sobre la capacidad de almacenamiento de carga (mC de carga almacenada / mg de polímero electrogenerado de aleaciones poliméricas de polipirrol/poli(ácido maléico-co-olefina, como paso inicial para la optimación de este material para su aplicación en baterías todo orgánicas. Las variables de estudio han sido: el potencial y el tiempo de polimerización, las concentraciones de pirrol y poli(ácido maléico-co-olefina y la temperatura de la solución de polimerización. Optimando estos parámetros se ha logrado sintetizar materiales con una capacidad promedio de almacenamiento de carga de 120 mC. mg-1.
Practical application of a commercial CFD package in a design/build environment
Energy Technology Data Exchange (ETDEWEB)
Berkoe, J; Krag, P; Rayner, C; Imrie, W [Bechtel Corp., San Francisco, CA (United States)
1996-08-01
Some examples of how computational fluid dynamics (CFD) has been used to solve problems in the design of metallurgical plants, were presented. CFD has been used to optimize equipment for several unit operations at Bechtel Mining and Metals, and also in developing technologies to improve environmental conditions in several facilities. Some examples included mixing in a copper refining furnace, flow in copper solvent extraction settlers, the ventilation of electrowinning tank houses, and the capture of fugitive emissions from Peirce-Smith converters. Cost effective use of CFD on such projects requires substantial investment in high-end computing equipment, versatile commercial CFD software and advanced data visualization, however, in the hands of a sophisticated analyst the results are well worth the expense. 21 refs., 2 tabs., 7 figs.
Ensayo sobre endurecimiento de adhesivos estructurales sometidos a cargas dinámicas
Directory of Open Access Journals (Sweden)
Recuero, A.
2004-04-01
Full Text Available Carbon fibre reinforced polymers are increasingly replacing the steel reinforcing systems in the repair and strengthening of concrete structures thanks to their high strength/weight and stiffness/weight ratios, corrosion resistance, lightweight, and ease of handling and application. This paper presents a study on the behaviour of bridge concrete beams strengthened with CFRP sheets when the strengthening is made when traffic is acting so that the structure is subjected to dynamic loads while the adhesive is still fresh. No reduction in the effectiveness of the strengthening was observed in the tests.
Los polímeros reforzados con fibras de carbono se están utilizando cada vez más para el refuerzo de estructuras de hormigón, reemplazando a los sistemas tradicionales de refuerzo con acero. Esto es debido a sus altas resistencia y rigidez específicas, resistencia a la corrosión, ligereza y facilidad de manejo y puesta en obra. Este artículo presenta un estudio sobre el comportamiento de vigas de puentes reforzadas con bandas de CFRP mientras se mantiene el puente en servicio de manera que la estructura está sometida a cargas dinámicas con el adhesivo fresco. En los ensayos realizados se ha observado que las cargas dinámicas no afectan a la efectividad del refuerzo.
CFD Vision 2030 Study: A Path to Revolutionary Computational Aerosciences
Slotnick, Jeffrey; Khodadoust, Abdollah; Alonso, Juan; Darmofal, David; Gropp, William; Lurie, Elizabeth; Mavriplis, Dimitri
2014-01-01
This report documents the results of a study to address the long range, strategic planning required by NASA's Revolutionary Computational Aerosciences (RCA) program in the area of computational fluid dynamics (CFD), including future software and hardware requirements for High Performance Computing (HPC). Specifically, the "Vision 2030" CFD study is to provide a knowledge-based forecast of the future computational capabilities required for turbulent, transitional, and reacting flow simulations across a broad Mach number regime, and to lay the foundation for the development of a future framework and/or environment where physics-based, accurate predictions of complex turbulent flows, including flow separation, can be accomplished routinely and efficiently in cooperation with other physics-based simulations to enable multi-physics analysis and design. Specific technical requirements from the aerospace industrial and scientific communities were obtained to determine critical capability gaps, anticipated technical challenges, and impediments to achieving the target CFD capability in 2030. A preliminary development plan and roadmap were created to help focus investments in technology development to help achieve the CFD vision in 2030.
PIV-measured versus CFD-predicted flow dynamics in anatomically realistic cerebral aneurysm models.
Ford, Matthew D; Nikolov, Hristo N; Milner, Jaques S; Lownie, Stephen P; Demont, Edwin M; Kalata, Wojciech; Loth, Francis; Holdsworth, David W; Steinman, David A
2008-04-01
Computational fluid dynamics (CFD) modeling of nominally patient-specific cerebral aneurysms is increasingly being used as a research tool to further understand the development, prognosis, and treatment of brain aneurysms. We have previously developed virtual angiography to indirectly validate CFD-predicted gross flow dynamics against the routinely acquired digital subtraction angiograms. Toward a more direct validation, here we compare detailed, CFD-predicted velocity fields against those measured using particle imaging velocimetry (PIV). Two anatomically realistic flow-through phantoms, one a giant internal carotid artery (ICA) aneurysm and the other a basilar artery (BA) tip aneurysm, were constructed of a clear silicone elastomer. The phantoms were placed within a computer-controlled flow loop, programed with representative flow rate waveforms. PIV images were collected on several anterior-posterior (AP) and lateral (LAT) planes. CFD simulations were then carried out using a well-validated, in-house solver, based on micro-CT reconstructions of the geometries of the flow-through phantoms and inlet/outlet boundary conditions derived from flow rates measured during the PIV experiments. PIV and CFD results from the central AP plane of the ICA aneurysm showed a large stable vortex throughout the cardiac cycle. Complex vortex dynamics, captured by PIV and CFD, persisted throughout the cardiac cycle on the central LAT plane. Velocity vector fields showed good overall agreement. For the BA, aneurysm agreement was more compelling, with both PIV and CFD similarly resolving the dynamics of counter-rotating vortices on both AP and LAT planes. Despite the imposition of periodic flow boundary conditions for the CFD simulations, cycle-to-cycle fluctuations were evident in the BA aneurysm simulations, which agreed well, in terms of both amplitudes and spatial distributions, with cycle-to-cycle fluctuations measured by PIV in the same geometry. The overall good agreement
An introduction to chaos theory in CFD
Pulliam, Thomas H.
1990-01-01
The popular subject 'chaos theory' has captured the imagination of a wide variety of scientists and engineers. CFD has always been faced with nonlinear systems and it is natural to assume that nonlinear dynamics will play a role at sometime in such work. This paper will attempt to introduce some of the concepts and analysis procedures associated with nonlinear dynamics theory. In particular, results from computations of an airfoil at high angle of attack which exhibits a sequence of bifurcations for single frequency unsteady shedding through period doublings cascading into low dimensional chaos are used to present and demonstrate various aspects of nonlinear dynamics in CFD.
Coarse-grid-CFD. An advantageous alternative to subchannel analysis
International Nuclear Information System (INIS)
Class, A.G.; Himmel, S.R.; Viellieber, M.O.
2011-01-01
In the 1960 th to 80 th when current GEN II reactor technology was developed, the only possible approach was to use one-dimensional subchannel analysis to compute the flow inside a fuel bundle so that the subchannel scale could be resolved. For simulations of the whole reactor core either system codes or homogenization were employed. In system codes resolution of individual assemblies was the state of the art. Homogenization used porous media equations simulations and averaged the thermohydraulics on reactor core scale. Current potent computing power allows using Computational Fluid Dynamics (CFD) to simulate individual fuel assemblies. Yet the large number of fuel assemblies within the core forbids exploiting CFD for core wide simulation. We propose to combine ideas of subchannel analysis and CFD to develop a new methodology which takes advantage of the fast development of commercial CFD software and the efficiency of subchannel analysis. In this methodology was first applied to simulate a wire-wrap fuel bundle of the High Performance Light Water Reactor (HPLWR). Computations using an inviscid Euler solver on an extremely coarse grid were tuned to predict the true thermohydraulics by adding volumetric forces. These forces represent the non-resolved sub-grid physics. The volumetric forces cannot be measured directly. However, they can be accessed from detailed CFD simulations resolving all relevant physics. Parameterization of these subgrid forces can be realized analogous to models in subchannel codes. In the present work we extend the methodology to the open source solver OpenFOAM and a specific hexagonal fuel assembly which is studied in the framework of liquid metal cooled GEN IV reactor concepts. (orig.)
CFD simulation of air to air enthalpy heat exchanger
International Nuclear Information System (INIS)
Al-Waked, Rafat; Nasif, Mohammad Shakir; Morrison, Graham; Behnia, Masud
2013-01-01
Highlights: • A CFD model capable of modelling conjugate heat and mass transfer processes. • A mesh independence studies and a CFD model validation have been conducted. • Effects of flow direction on the effectiveness have been examined. • Performance parameters were sensible and latent effectiveness and pressure drop. - Abstract: A CFD model which supports conjugate heat and mass transfer problem representation across the membrane of air-to-air energy recovery heat exchangers has been developed. The model consists of one flow passage for the hot stream and another for the adjacent cold stream. Only half of each flow passage volume has been modelled on each side of the membrane surface. Three dimensional, steady state and laminar flow studies have been conducted using a commercial CFD package. The volumetric species transport model has been adopted to describe the H 2 O and air gas mixtures. Mesh dependency has been examined and followed by validation of the CFD model against published data. Furthermore, effects of flow direction at the inlet of the heat exchanger on its thermal effectiveness have been investigated. Simulation results are presented and analysed in terms of sensible effectiveness, latent effectiveness and pressure drop across the membrane heat exchanger. Results have shown that counter-flow configuration has greater sensitivity to the mesh centre perpendicular distance from the membrane when compared to the other two flow configurations (cross-/parallel-flow). However, the lateral mesh element length has shown minimal effect on the thermal effectiveness of the enthalpy heat exchanger. For the quasi-flow heat exchanger, a perpendicular flow direction to the inlets has been found to produce a higher performance in contrast to the non-perpendicular flow
Energy Technology Data Exchange (ETDEWEB)
Cristin V, Miguel A; Ortega S, Cesar A [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)
2005-07-01
The charge of lead-acid batteries (LAB), as in any other type of batteries, consists of replacing the energy consumed during the discharge. Nevertheless, as no physical or chemical process is good enough to totality recharge a battery, it is necessary to supply to it more than the 100% of the energy demanded during its discharge. A critical factor to make a suitable load control of the batteries is to determine its own state of load. That is to say, to have an efficient load control, it is necessary to count on means that allow to accurately determining the residual capacity of the battery to deliver load. This one is the one of the aspects of greater interest in the research centers around world. For this reason, in this work it was pretended to develop a calculation algorithm of the state of load of batteries based on a fuzzy-neural network that could calculate the state of load without using the battery current as an input. This is because one of the main problems for the designers of battery load controllers is the correct supervision of the current that circulates around the system in all the rank of operation of the same one because the sensors do not have a linear behavior. [Spanish] La recarga de baterias plomo-acido (BPA), como cualquier otro tipo de baterias, consiste en reponer la energia consumida durante la descarga. Sin embargo, como ningun proceso fisico o quimico es lo bastante eficiente para recargar a totalidad una bateria, es necesario suministrarle mas del 100% de la energia demandada durante su descarga. Un factor critico para realizar un adecuado control de carga de las baterias, es determinar su propio estado de carga. Es decir, para tener un control de carga eficiente, es necesario contar con un medio que permita determinar con precision la capacidad remanente de la bateria para entregar carga. Este es uno de los aspectos de mayor interes en los centros de investigacion alrededor el mundo. Por tal razon, en este trabajo se propuso
Development and acceleration of unstructured mesh-based cfd solver
Emelyanov, V.; Karpenko, A.; Volkov, K.
2017-06-01
The study was undertaken as part of a larger effort to establish a common computational fluid dynamics (CFD) code for simulation of internal and external flows and involves some basic validation studies. The governing equations are solved with ¦nite volume code on unstructured meshes. The computational procedure involves reconstruction of the solution in each control volume and extrapolation of the unknowns to find the flow variables on the faces of control volume, solution of Riemann problem for each face of the control volume, and evolution of the time step. The nonlinear CFD solver works in an explicit time-marching fashion, based on a three-step Runge-Kutta stepping procedure. Convergence to a steady state is accelerated by the use of geometric technique and by the application of Jacobi preconditioning for high-speed flows, with a separate low Mach number preconditioning method for use with low-speed flows. The CFD code is implemented on graphics processing units (GPUs). Speedup of solution on GPUs with respect to solution on central processing units (CPU) is compared with the use of different meshes and different methods of distribution of input data into blocks. The results obtained provide promising perspective for designing a GPU-based software framework for applications in CFD.
Capacidade de Carga em Cidades Históricas
Directory of Open Access Journals (Sweden)
Fernando Vicente de Oliveira
2010-08-01
Full Text Available Neste artigo são apresentados os conceitos de capacidade de carga e capacidade ambiental vinculando-os ao manejo de cidades históricas dentro dos pressupostos do turismo sustentável. A avaliação da capacidade ambiental é uma valiosa ferramenta para planejamento turístico. O principal é determinar até que ponto um meio ambiente pode suportar uma intervenção, sem que a mesma danifique ou prejudique a característica principal deste local. As cidades históricas e turísticas com desejo de fomentar o turismo devem, necessariamente, delimitar suas capacidades de crescimento, para geração de riquezas através de sua economia diversificada e, sobretudo, bem estar de sua população, principal objetivo do estudo de capacidade ambiental.
CFD simulation of crossflow mixing in a rod bundle with mixing blades
International Nuclear Information System (INIS)
In, W. K.
1999-01-01
A CFD model was developed in this study to simulate the crossflow mixing in a 4x4 square array rod bundle caused by ripped-open blades. The central subchannel and adjacent subchannels of one grid span were modeled using flow symmetry. The lateral velocity pattern within the central subchannel, lateral velocity and the turbulence intensity in the rod gap region were predicted by the CFD method, and the predictions were compared with the measurements. The CFD simulation shows a vortex flow around the fuel rod caused by a pair of blades, which is consistent with the experimental results. The CFD predictions of the lateral velocity on the mixing sections show a near symmetric profile, but the measurements present an asymmetric velocity profile leading to an inversion of lateral velocity. The predicted mixing rate between the central subchannel and the adjacent subchannels reasonably agrees with the measured one. The CFD prediction shows a parabolic distribution of the RMS velocity but the measured one shows a rather flat distribution near the blade that develops to a parabolic distribution far downstream (L=29De). The predicted average RMS velocity on a mixing section is also slightly lower than the measured one. This study confirmed that the CFD simulation can present the effect of the ripped-open blades on the crossflow mixing in a rod bundle well
Numerical CFD Simulation and Test Correlation in a Flight Project Environment
Gupta, K. K.; Lung, S. F.; Ibrahim, A. H.
2015-01-01
This paper presents detailed description of a novel CFD procedure and comparison of its solution results to that obtained by other available CFD codes as well as actual flight and wind tunnel test data pertaining to the GIII aircraft, currently undergoing flight testing at AFRC.
Comportamiento de paneles de bambú guadua laminado ante cargas paralelas al plano
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Juan Jacobo Pinilla Rodríguez
2012-05-01
Full Text Available Como un primer paso en el estudio del comportamiento ante cargas sísmicas de pórticos de bambú guadua laminados con paneles del mismo material, el Grupo de Investigación “Análisis, Diseño y Materiales, GIES”, de la Universidad Nacional de Colombia, ensayó dos tipos de paneles elaborados con bambú Guadua angustifolia Kunth y poli (vinil acetato, PVA: los paneles tipo 1 de sección transversal maciza y los paneles tipo 2 de sección transversal tipo sándwich.Se consideraron tres alturas para cada tipo de panel y se ensayaron diez réplicas por altura y por tipo, para un total de sesenta ensayos.Para cada uno de los paneles ensayados se realizó una curva carga-desplazamiento. Los paneles tipo 1, con altura de 0,34 m y 0,63 m, mostraron un comportamiento elástico inicial seguido de un comportamiento inelástico, mientras que los paneles tipo 1 y 2 de 0,98 m de altura revelaron un comportamiento casi totalmente elástico hasta la falla. Todos los paneles sufrieron aplastamiento en la base; sin embargo, el principal mecanismo de falla fue el alabeo.
Controle pela carga de trabalho de um sistema flexível de manufatura
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Daniel Battaglia
2016-04-01
Full Text Available O objetivo deste artigo foi calcular tempos de atravessamento e inventário médios em um sistema de manufatura flexível, que atende muitas ordens, de tamanho e mix variado. Foi aplicado o workload control (controle por carga de trabalho para o cálculo da situação atual, e simulação computacional (software ProModel para avaliar duas situação alternativas: aumento na demanda e redução na demanda. O método de pesquisa foi a modelagem quantitativa. Os resultados apontam que atualmente há excesso de inventário, provocado por desequilíbrio entre demanda e entrega da manufatura, o que é típico em sistemas de filas. Seria necessário sincronizar melhor entradas e saídas. Os cenários simulados apontam que a manufatura não suporta aumento de carga, crescendo continuamente o inventário, até a operação tornar-se inviável. Para estabilidade do inventário, seria necessário reduzir a demanda, se for mantido o atual regime de trabalho, com entradas aleatórias e independentes.
Directory of Open Access Journals (Sweden)
Juan Manuel Yañez Arauz
2016-05-01
Full Text Available Introducción La reducción y osteosíntesis de las fracturas del tobillo, permiten una recuperación precoz. Sin embargo, clásicamente no se permite la carga del peso durante casi 6 semanas. El objetivo del presente estudio, es analizar si la carga inmediata del peso en fracturas de peroné, produce complicaciones y/o desplazamientos secundarios. Material y métodos Se analizaron 21 pacientes operados de fracturas 44AOB1, y se les dio carga inmediata. Se evaluó clínica y radiográficamente la evolución de los mismos. El seguimiento fue a más de 3 meses. Resultados La carga del peso con protección con bota “Walker”, fue ejecutada por los pacientes a los 2 días promedio. El puntaje AOFAS para tobillo evaluado a los 3 meses del post-operatorio fue de 99 puntos promedio. El retorno a la actividad laboral fue promedio 2,1 meses; y el retorno a la actividad deportiva previa, fue promedio de 2,95 meses. En la radiología del POP a más de 90 días de seguimiento, la reducción no sufrió desplazamientos secundarios. Discusión Aun existe controversia sobre el manejo postoperatorio en las fracturas de tobillo. Actualmente se sabe que el movimiento temprano luego de la fijación interna, es beneficioso para disminuir la enfermedad del yeso. La carga de peso temprana facilitaron la restauración de la amplitud de movimiento de la articulación lesionada, disminuyeron la hinchazón, la atrofia de los tejidos blandos, y previnieron el desarrollo de osteoporosis. Conclusiones Las fracturas tipo AO 44B1 de baja energía, tratados mediante reducción y osteosíntesis, pueden realizar carga de peso precoz, sin riesgo de desplazamientos secundarios. La carga precoz junto a la movilización temprana, presenta muy buena evolución clínica, y no incide en un mayor índice de complicaciones.
Study of tip loss corrections using CFD rotor computations
DEFF Research Database (Denmark)
Shen, Wen Zhong; Zhu, Wei Jun; Sørensen, Jens Nørkær
2014-01-01
Tip loss correction is known to play an important role for engineering prediction of wind turbine performance. There are two different types of tip loss corrections: tip corrections on momentum theory and tip corrections on airfoil data. In this paper, we study the latter using detailed CFD...... computations for wind turbines with sharp tip. Using the technique of determination of angle of attack and the CFD results for a NordTank 500 kW rotor, airfoil data are extracted and a new tip loss function on airfoil data is derived. To validate, BEM computations with the new tip loss function are carried out...... and compared with CFD results for the NordTank 500 kW turbine and the NREL 5 MW turbine. Comparisons show that BEM with the new tip loss function can predict correctly the loading near the blade tip....
OpenFOAM: Open source CFD in research and industry
Jasak, Hrvoje
2009-12-01
The current focus of development in industrial Computational Fluid Dynamics (CFD) is integration of CFD into Computer-Aided product development, geometrical optimisation, robust design and similar. On the other hand, in CFD research aims to extend the boundaries ofpractical engineering use in "non-traditional " areas. Requirements of computational flexibility and code integration are contradictory: a change of coding paradigm, with object orientation, library components, equation mimicking is proposed as a way forward. This paper describes OpenFOAM, a C++ object oriented library for Computational Continuum Mechanics (CCM) developed by the author. Efficient and flexible implementation of complex physical models is achieved by mimicking the form ofpartial differential equation in software, with code functionality provided in library form. Open Source deployment and development model allows the user to achieve desired versatility in physical modeling without the sacrifice of complex geometry support and execution efficiency.
Análisis de falla en cable de acero Análisis de falla en cable de acero
Directory of Open Access Journals (Sweden)
E. A. Ossa
2005-12-01
Full Text Available Este artículo describe el análisis de falla realizado en dos muestras de cables de acero que sufrieron falla súbita bajo condiciones de carga de trabajo normales. La falla fue causada por una carga menor a la capacidad nominal. Luego de inspección óptica se evidenció que la falla fue ocasionada por fatiga del material de uno de los cables.This paper describes the failure analysis of two wire ropes fractured during normal working conditions. The failure was caused by a load well below the nominal maximum resistance of the ropes. Optical microscopy indicated fatigue failure of one of the cables.
Respostas cardiovasculares ao exercício resistido são afetadas pela carga e intervalos entre séries
Directory of Open Access Journals (Sweden)
Antonio Gil Castinheiras-Neto
2010-10-01
Full Text Available FUNDAMENTO: O controle das respostas cardiovasculares durante exercício resistido (ER é importante para a segurança do paciente. OBJETIVO: Investigar a influência do número de repetições máximas (RM e dos intervalos de recuperação entre séries (IR sobre a frequência cardíaca (FC, pressão arterial sistólica (PAS e duplo produto (DP durante ER. MÉTODOS: Vinte sujeitos saudáveis (26 ± 5 anos realizaram protocolos de ER envolvendo três séries do leg press (6 e 12 RM e IR proporcional ao tempo de contração (1:3 e 1:5. Aferiu-se a FC continuamente com cardiofrequencímetro e a PAS foi verificada ao final das séries, por meio de protocolo validado com método auscultatório. RESULTADOS: A FC sofreu influência da carga (p = 0,008 e das séries (p < 0,001, mas não do IR (p = 0,087. A PAS sofreu efeito isolado do número de séries (p < 0,001 e do IR (p = 0,017, mas não da carga (p = 0,95. O DP elevou-se em relação direta com a carga (p = 0,036 e com as séries (p < 0,001, mas inversamente ao IR (p = 0,006. Nos protocolos de 6 RM, a variação da FC foi maior para IR = 1:3 (Δ = 11,2 ± 1,1 bpm do que para IR = 1:5 (Δ = 4,5 ± 0,2 bpm; p = 0,002, mas não houve diferença para 12 RM (Δ 1:3 = 21,1 ± 2,2 bpm; Δ 1:5 = 18,9 ± 2,0 bpm, p = 0,83. O IR influenciou a variação da PAS em todas as cargas (6 RM - Δ 1:3 = 10,6 ± 0,9 mmHg, Δ 1:5 = 6,6 ± 0,7 mmHg; p = 0,02 e 12 RM - Δ 1:3 = 15,2 ± 1,1 mmHg, Δ 1:5 = 8,4 ± 0,7 mmHg; p = 0,04. O DP elevou-se proporcionalmente à carga (p = 0,036 e para séries (p < 0,001, mas inversamente ao IR (p = 0,006. Com IR = 1:3, houve diferença de DP para 6 RM (Δ = 2.892 ± 189 mmHg.bpm e 12 RM (Δ = 4.587 ± 300 mmHg.bpm; p = 0,018, mas não com IR = 1:5 (6 RM: Δ = 1.224 ± 141 mmHg.bpm, 12 RM: Δ = 2.332 ± 194 mmHg.bpm; p = 0,58. CONCLUSÃO: Independentemente da carga, um maior IR associou-se a menores respostas cardiovasculares durante ER, especialmente de PAS.
CFD Modeling in Development of Renewable Energy Applications
Maher A.R. Sadiq Al-Baghdadi
2013-01-01
Chapter 1: A Multi-fluid Model to Simulate Heat and Mass Transfer in a PEM Fuel Cell. Torsten Berning, Madeleine Odgaard, Søren K. Kær Chapter 2: CFD Modeling of a Planar Solid Oxide Fuel Cell (SOFC) for Clean Power Generation. Meng Ni Chapter 3: Hydrodynamics and Hydropower in the New Paradigm for a Sustainable Engineering. Helena M. Ramos, Petra A. López-Jiménez Chapter 4: Opportunities for CFD in Ejector Solar Cooling. M. Dennis Chapter 5: Three Dimensional Modelling of Flow Field Around a...
CFD optimization of a pellet burner
Directory of Open Access Journals (Sweden)
Westerlund Lars B.
2012-01-01
Full Text Available Increased capacity of computers has made CFD technology attractive for the design of different apparatuses. Optimization of a pellet burner using CFD was investigated in this paper. To make the design tool work fast, an approach with only mixing of gases was simulated. Other important phenomena such as chemical reactions were omitted in order to speed up the design process. The original design of the burner gave unsatisfactory performance. The optimized design achieved from simulation was validated and the results show a significant improvement. The power output increased and the emission of unburned species decreased but could be further reduced. The contact time between combustion gases and secondary air was probably too short. An increased contact time in high temperature conditions would possibly improve the design further.
SIMULACIÓN DE PRUEBAS DE CARGA EN PILOTES USANDO UN MODELO CONSTITUTIVO HIPOPLÁSTICO
Directory of Open Access Journals (Sweden)
Juan Carlos Ruge Cárdenas
Full Text Available La presente investigación tuvo como objetivo principal, simular mediante el empleo de un programa basado en el método de elementos finitos, los resultados obtenidos de pruebas de carga en pilotes individuales fundados en arcillas porosas de Brasilia DF (Brasil, las cuales poseen características metaestables. Para las simulaciones se empleó la ecuación constitutiva hipoplástica. Los parámetros del suelo fueron obtenidos por medio de ensayos de laboratorio que permitieron estimar propiedades geotécnicas del suelo, así como parámetros de resistencia, deformabilidad e identificación estratigráfica. Como conclusión general se reporta que la predicción aportada por el modelo hipoplástico en relación a las pruebas de carga en el tramo antes de la ruptura es aceptable, sin embargo debido a la pérdida de adhesión en la interface suelo-pilote en el momento de la prueba, se nota la incapacidad del modelo para simular este efecto de manera adecuada, ya que existen condiciones de metaestabilidad y de parcial saturación presentes en el problema geotécnico.
Development of a three-dimensional CFD model for rotary lime kilns
Energy Technology Data Exchange (ETDEWEB)
Lixin Tao; Blom, Roger (FS Dynamics Sweden AB, Goeteborg (Sweden)); Nordgren, Daniel (Innventia, Stockholm (Sweden))
2010-11-15
In the calcium loop of the recovery cycle in a Kraft process of pulp and paper production, rotary lime kilns are used to convert the lime mud, mainly CaCO3, back to quick lime, CaO, for re-use in the causticizing process. The lime kilns are one of the major energy consumption devices for paper and pulp industry. Because of the rising oil price and new emission limits, the pulp mills have been forced to look for alternative fuels for their lime kilns. One interesting alternative to oil, often easily available at pulp mills, is biofuels such as sawdust and bark. However the practical kiln operation often encounters some difficulties because of the uncertainties around the biofuel impact on the lime kiln performance. A deeper understanding of the flame characteristics is required when shifting from oil to biofuels. Fortunately recent advances in modern Computational Fluid Dynamics, CFD, have provided the possibility to study and predict the detailed flame characteristics regarding the lime kiln performance. In this project a three-dimensional CFD model for rotary lime kilns has been developed. To simulate a rotary lime kiln the developed CFD model integrates the three essential sub-models, i.e. the freeboard hot flow model, the lime bed model and the rotating refractory wall model and it is developed based on the modern CFD package: FLUENT which is commercially available on the market. The numerical simulations using the developed CFD model have been performed for three selected kiln operations fired with three different fuel mixtures. The predicted results from the CFD modelling are presented and discussed in order to compare the impacts on the kiln performance due to the different firing conditions. During the development, the lime kiln at the Soedra Cell Moensteraas mill has been used as reference kiln. To validate the CFD model, in-plant measurements were carried out in the Moensteraas lime kiln during an experiment campaign. The results obtained from the
Assessment of Turbulent CFD Against STS-128 Hypersonic Flight Data
Wood, William A.; Kleb, William L.; Hyatt, Andrew J.
2010-01-01
Turbulent CFD simulations are compared against surface temperature measurements of the space shuttle orbiter windward tiles at reentry flight conditions. Algebraic turbulence models are used within both the LAURA and DPLR CFD codes. The flight data are from temperature measurements obtained by seven thermocouples during the STS-128 mission (September 2009). The flight data indicate boundary layer transition onset over the Mach number range 13.5{15.5, depending upon the location on the vehicle. But the boundary layer flow appeared to be transitional down through Mach 12, based upon the flight data and CFD trends. At Mach 9 the simulations match the flight data on average within 20 F/11 C, where typical surface temperatures were approximately 1600 F/870 C.
on Ti6AL4V for biomedical applications
Directory of Open Access Journals (Sweden)
Juan José Pavón
2006-01-01
Full Text Available La fijación al tejido receptor de implantes para el reemplazo de hueso puede ser mejorada si poseen una superficie bioactiva con la capacidad de precipitar hidroxiapatita in vivo. Las aleaciones de titanio, a pesar de sus buenas propiedades mecánicas y comportamiento no-tóxico, no son bioactivas y, por tanto, no se enlazan directamente al hueso. Una de las maneras de modificar una superficie metálica bioinerte es recubriéndola con material bioactivo. En este trabajo se presenta la evaluación del comportamiento a fatiga mediante indentación hertziana (esférica de un recubrimiento de vidrio sobre Ti6Al4V. Este recubrimiento pertenece al sistema SiO2-CaO-MgO-Na2O-K2O-P2O5 y, a pesar de que puede usarse para protección contra la corrosión, ha sido específicamente diseñado para ser utilizado como capa interna de un recubrimiento bicapa bioactivo con una capa externa de bajo contenido en SiO2 para garantizar la bioactividad. Los ensayos hertzianos monotónicos permitieron obtener una secuencia de daños comenzando con tres eventos de daño tipo frágil (agrietamiento tipo anillo, cono y radial seguidos por la delaminación del recubrimiento asociada a la deformación plástica del substrato. El primer daño frágil, el agrietamiento tipo anillo, fue usado como criterio para la evaluación del agrietamiento por corrosión bajo tensión y por carga cíclica, en aire y agua destilada. Los resultados mostraron la sensibilidad del recubrimiento a la degradación bajo ambos tipos de carga, estática y cíclica, siendo esta degradación considerablemente mayor en agua destilada debido a la susceptibilidad del vidrio a la corrosión. La delaminación fue también sensible a la carga cíclica hertziana presentando dos mecanismos diferentes dependiendo de la máxima carga aplicada.
Perubahan Sosial Pada Komunitas Suku Bajo Di Pesisir Teluk Tomini
Directory of Open Access Journals (Sweden)
Muhammad Obie
2016-06-01
Full Text Available Abstract: Society and culture of human being always change as an ever –present phenomena in the world. A distinction is sometimes made then between processes of change within the social structure, which serve in part to maintain the structure, and, even the processes itself can be slow or fast through evolusion and revolusion. One of the factors that quicken the social change process is the government interventions. This study aims at analyzing the social change on the Bajo Tribe community as the impact of various government programs at Tomini bay coastal. This research used strategy of historical sociology. The kinds of data collected were primer and secondary data that were analyzed by using qualitative approac. The result showed that various government programs at Tomini bay, such as designating conservation area, granting concession license to private sectors through forest concession right (FCR, indefeasible right of use (IRU, and fishing industry at the bay had caused the loss of access of the Bajo tribe community to coastal and marine resources area. Various interventions of government programs had implication on resettlement of the Bajo tribe community, causing the Bajo tribe divided into sea Bajo and land Bajo. The loss of access of the Bajo tribe to coastal and marine resources caused traditional institution weaken which made its philosophy of living in harmony with nature, and conservation ethics fade away, its local wisdom, and self identity lose, and its social capital destructed. الملخص: كان المجتمع وحضارته متغيّرين في أيّ كان المجتمع وهذه الحضارة. ويكون الفرق في كون هذا التغيّر. قد تكون عملية التغيّر متمهّلة أو سريعة وقد تكون عن طريق التطوّر والثّورة. وأحد العناصر المسرعة في عملية هذا التغيّر هو تدخّل الحكومة. حاولت هذه
Directory of Open Access Journals (Sweden)
Lucimara Ballardin
2009-01-01
Full Text Available Este artigo mostra o método adotado e os resultados obtidos em estudo realizado com operadores de uma distribuidora de derivados de petróleo da região Sul do Brasil. O objetivo era avaliar a carga de trabalho e os fatores que interferem nessa carga, do ponto de vista dos operadores. A metodologia aplicada incluiu entrevistas e dois questionários, um adaptado do NASA-TLX e um para levantamento dos fatores que interferem na carga de trabalho. Os resultados indicaram que a maioria dos operadores percebe que a carga de trabalho é alta. Entre os componentes da carga de trabalho, o desempenho é a que tem peso maior, enquanto os problemas relacionados a equipamentos e sistemas informatizados são os que mais influenciam nessa carga. Tendo em vista os resultados obtidos, é necessário aperfeiçoar os subsistemas, técnico e organizacional, da empresa para gerar melhorias na performance, saúde e satisfação dos operadores.The aim of this study was to evaluate workloads as perceived by the operators of an oil distribution company in Southern Brazil. Workload levels were measured by a questionnaire adapted from the NASA-TLX, and the factors that impact on the workload were identified by interviews and questionnaire. The results showed that the workload level is high, mainly due to technical constraints (such as equipment and computational problems. Performance is the component which most influences workload. According to the results, it is necessary to improve the technical and organizational subsystems of the oil distribution company in order to improve human performance as well as the health and safety of the operators.
Design of 500kW grate fired test facility using CFD
DEFF Research Database (Denmark)
Rosendahl, Lasse Aistrup; Kær, Søren Knudsen; Jørgensen, K.
2005-01-01
A 500kW vibrating grate fired test facility for solid biomass fuels has been designed using numerical models including CFD. The CFD modelling has focussed on the nozzle layout and flowpatterns in the lower part of the furnace, and the results have established confidence in the chosen design...
Sellers, William L., III; Dwoyer, Douglas L.
1992-01-01
The design of a hypersonic aircraft poses unique challenges to the engineering community. Problems with duplicating flight conditions in ground based facilities have made performance predictions risky. Computational fluid dynamics (CFD) has been proposed as an additional means of providing design data. At the present time, CFD codes are being validated based on sparse experimental data and then used to predict performance at flight conditions with generally unknown levels of uncertainty. This paper will discuss the facility and measurement techniques that are required to support CFD development for the design of hypersonic aircraft. Illustrations are given of recent success in combining experimental and direct numerical simulation in CFD model development and validation for hypersonic perfect gas flows.
Directory of Open Access Journals (Sweden)
Leise Kelli de Oliveira
2016-09-01
Full Text Available A distribuição urbana de mercadorias está diretamente relacionada ao desenvolvimento econômico, apesar dos impactos negativos relacionados a esta atividade. Uma forma de minimizar tais impactos é utilizando-se políticas públicas e, para isto, os modelos de geração de viagens de carga podem ser uma estratégica para conhecer o comportamento do fluxo de carga no meio urbano. Nesse contexto, este trabalho revisa os modelos de geração de viagens de carga no contexto brasileiro e propõe modelos para importantes setores em Belo Horizonte: Bares, Restaurantes, Mercados e Supermercados. Para tanto, utilizou-se de pesquisa de campo para coleta de informações nos segmentos analisados, cujos dados foram analisados buscando determinar a melhor correlação entre as variáveis que descrevem a geração de viagens. Os resultados obtidos indicaram que a taxa de geração de viagens em relação à área do estabelecimento comercial foi o modelo que apresentou o melhor ajuste. Além disso, o desenvolvimento de modelos para as diferentes regionais da cidade, além do modelo geral, indicou a importância de análises locais para a avaliação da movimentação da carga. Por fim, a comparação dos modelos obtidos com os modelos encontrados na literatura brasileira indicou semelhanças e divergências e reforçou a necessidade de modelos locais, especializados para os diferentes setores econômicos.
CFD simulation research on residential indoor air quality.
Yang, Li; Ye, Miao; He, Bao-Jie
2014-02-15
Nowadays people are excessively depending on air conditioning to create a comfortable indoor environment, but it could cause some health problems in a long run. In this paper, wind velocity field, temperature field and air age field in a bedroom with wall-hanging air conditioning running in summer are analyzed by CFD numerical simulation technology. The results show that wall-hanging air conditioning system can undertake indoor heat load and conduct good indoor thermal comfort. In terms of wind velocity, air speed in activity area where people sit and stand is moderate, most of which cannot feel wind flow and meet the summer indoor wind comfort requirement. However, for air quality, there are local areas without ventilation and toxic gases not discharged in time. Therefore it is necessary to take effective measures to improve air quality. Compared with the traditional measurement method, CFD software has many advantages in simulating indoor environment, so it is hopeful for humans to create a more comfortable, healthy living environment by CFD in the future. Copyright © 2013 Elsevier B.V. All rights reserved.
Grid deformation strategies for CFD analysis of screw compressors
Rane, S.; Kovacevic, A.; Stosic, N.; Kethidi, M.
2013-01-01
Customized grid generation of twin screw machines for CFD analysis is widely used by the refrigeration and air-conditioning industry today, but is currently not suitable for topologies such as those of single screw, variable pitch or tri screw rotors. This paper investigates a technique called key-frame re-meshing that supplies pre-generated unstructured grids to the CFD solver at different time steps. To evaluate its accuracy, the results of an isentropic compression-expansion process in a r...
BALANCE DE CARGA DINAMICO PARA OBJETOS ACTIVOS MOVILES EN GRILLAS DE COMPUTADORES
BUSTOS JIMENEZ, JAVIER ALEJANDRO; BUSTOS JIMENEZ, JAVIER ALEJANDRO
2006-01-01
Esta tesis apunta a entregar las bases para el desarrollo de los algoritmos de balance de carga para el modelo de objetos activos definido por ProActive en el contexto de las redes a gran escala (grillas). ProActive es un middleware implementado en lenguaje Java, de código abierto, para la programación concurrente, paralela, distribuida, y móvil; basado en el modelo de objeto-activo. En ProActive, cada objeto activo tiene su propio hilo de control y puede decidir independientemente e...
Adaptive Distributed Data Structure Management for Parallel CFD Applications
Frisch, Jerome
2013-09-01
Computational fluid dynamics (CFD) simulations require a lot of computing resources in terms of CPU time and memory in order to compute with a reasonable physical accuracy. If only uniformly refined domains are applied, the amount of computing cells is growing rather fast if a certain small resolution is physically required. This can be remedied by applying adaptively refined grids. Unfortunately, due to the adaptive refinement procedures, errors are introduced which have to be taken into account. This paper is focussing on implementation details of the applied adaptive data structure management and a qualitative analysis of the introduced errors by analysing a Poisson problem on the given data structure, which has to be solved in every time step of a CFD analysis. Furthermore an adaptive CFD benchmark example is computed, showing the benefits of an adaptive refinement as well as measurements of parallel data distribution and performance. © 2013 IEEE.
OpenFOAM: Open source CFD in research and industry
Directory of Open Access Journals (Sweden)
Hrvoje Jasak
2009-12-01
Full Text Available The current focus of development in industrial Computational Fluid Dynamics (CFD is integration of CFD into Computer-Aided product development, geometrical optimisation, robust design and similar. On the other hand, in CFD research aims to extend the boundaries of practical engineering use in “non-traditional” areas. Requirements of computational flexibility and code integration are contradictory: a change of coding paradigm, with object orientation, library components, equation mimicking is proposed as a way forward. This paper describes OpenFOAM, a C++ object oriented library for Computational Continuum Mechanics (CCM developed by the author. Efficient and flexible implementation of complex physical models is achieved by mimicking the form of partial differential equation in software, with code functionality provided in library form. Open Source deployment and development model allows the user to achieve desired versatility in physical modeling without the sacrifice of complex geometry support and execution efficiency.
SFO-Project: The New Generation of Sharable, Editable and Open-Access CFD Tutorials
Javaherchi, Teymour; Javaherchi, Ardeshir; Aliseda, Alberto
2016-11-01
One of the most common approaches to develop a Computational Fluid Dynamic (CFD) simulation for a new case study of interest is to search for the most similar, previously developed and validated CFD simulation among other works. A simple search would result into a pool of written/visual tutorials. However, users should spend significant amount of time and effort to find the most correct, compatible and valid tutorial in this pool and further modify it toward their simulation of interest. SFO is an open-source project with the core idea of saving the above-mentioned time and effort. This is done via documenting/sharing scientific and methodological approaches to develop CFD simulations for a wide spectrum of fundamental and industrial case studies in three different CFD solvers; STAR-CCM +, FLUENT and Open FOAM (SFO). All of the steps and required files of these tutorials are accessible and editable under the common roof of Github (a web-based Git repository hosting service). In this presentation we will present the current library of 20 + developed CFD tutorials, discuss the idea and benefit of using them, their educational values and explain how the next generation of open-access and live resource of CFD tutorials can be built further hand-in-hand within our community.
CFD analysis of a diaphragm free-piston Stirling cryocooler
Caughley, Alan; Sellier, Mathieu; Gschwendtner, Michael; Tucker, Alan
2016-10-01
This paper presents a Computational Fluid Dynamics (CFD) analysis of a novel free-piston Stirling cryocooler that uses a pair of metal diaphragms to seal and suspend the displacer. The diaphragms allow the displacer to move without rubbing or moving seals. When coupled to a metal diaphragm pressure wave generator, the system produces a complete Stirling cryocooler with no rubbing parts in the working gas space. Initial modelling of this concept using the Sage modelling tool indicated the potential for a useful cryocooler. A proof-of-concept prototype was constructed and achieved cryogenic temperatures. A second prototype was designed and constructed using the experience gained from the first. The prototype produced 29 W of cooling at 77 K and reached a no-load temperature of 56 K. The diaphragm's large diameter and short stroke produces a significant radial component to the oscillating flow fields inside the cryocooler which were not modelled in the one-dimensional analysis tool Sage that was used to design the prototypes. Compared with standard pistons, the diaphragm geometry increases the gas-to-wall heat transfer due to the higher velocities and smaller hydraulic diameters. A Computational Fluid Dynamics (CFD) model of the cryocooler was constructed to understand the underlying fluid-dynamics and heat transfer mechanisms with the aim of further improving performance. The CFD modelling of the heat transfer in the radial flow fields created by the diaphragms shows the possibility of utilizing the flat geometry for heat transfer, reducing the need for, and the size of, expensive heat exchangers. This paper presents details of a CFD analysis used to model the flow and gas-to-wall heat transfer inside the second prototype cryocooler, including experimental validation of the CFD to produce a robust analysis.
Bajo materialismo y surrealismo. El debate Bataille-Breton
Directory of Open Access Journals (Sweden)
Noelia Denise Dunan
2015-01-01
Full Text Available Hacia 1923 Georges Bataille era un joven desconocido que comenzaba a entablar amistades y también enemistades en el núcleo del movimiento surrealista e intelectual de París. Alentado por algunos de aquellos vínculos, lee a Mauss y Durkheim, Nietzsche y Freud y, comienza a delinear un pensamiento que se plasmará en la creación de Documents. Resulta difícil comprender la relevancia de esta revista y la producción batailleana sin referir a sus primeras lecturas y al debate que tempranamente entabló con el máximo exponente del movimiento surrealista, André Breton. Bataille coordinó allí un grupo de disidentes y convirtió la publicación en una máquina contra el surrealismo. El presente artículo desarrolla la formación de Bataille para hacer hincapié en la categoría de bajo materialismo construida en tensión entre el idealismo surrealista y los distintos materialismos. Así puede verse que Documents y el bajo materialismo conjugan las preocupaciones que perseguirá toda su vida.
Influencia de Las Cargas Térmicas Sobre Flujos de Aire Generados en Una Habitación
DEFF Research Database (Denmark)
Olmedo, Inés; de Adana, Manuel Ruiz; Nielsen, Peter V.
La distribución de aire generada por los difusores en recinto interiores es crucial para obtener las características de aire y confort térmico deseadas. Los difusores de baja velocidad son altamente recomendados para muchas aplicaciones por sus numerosas ventajas. Sin embargo las cargas térmicas...
Determinação do ponto de carga zero em solos Determination of the zero point of charge in soils
Directory of Open Access Journals (Sweden)
Bernardo van Raij
1973-01-01
Full Text Available São apresentados os fundamentos e dois métodos de determinação do ponto de carga zero (PCZ em solos. Por um dos métodos o PCZ foi determinado como sendo o pH do ponto de cruzamento de curvas de titulação dos solos em soluções de NaCl 1; 0.1; 0 01; c 0,001N. Pelo outro método o PCZ foi determinado por extrapolação ou interpolação da carga líquida dos solos, determinada por retenção de íons em soluções de NaCl 0,2N, CaCl2 0,01N e MgSO4 0,01N, ao valor de pH em que a carga líquida era nula.The zero point of charge (ZPC of soils was determined by the crossing point of acid-base potenciometric titration curves in different concentrations of NaCl. Alternatively, the ZPC was found by extrapolating or interpolating the net electric charge of soils, determined by direct adsorption of ions from solution of NaCl, CaCl2 and MgSO4, to the pH of charge zero.
El papel del pastoreo en la reducción de la carga de combustible en los bosques de la Vall d'Alinyà
Forestalia (Grup de recerca)
2014-01-01
Títol variant: The role of extensive ranching in reducing fuel loads in the forests of the Alinyà Valley Este estudio pretende mostrar como una gestión mediante pastura extensiva puede ayudar entre otros beneficios ecológicos y sociales a disminuir la carga de combustible forestal, reducir el riesgo de incendios y mejorar la biodiversidad. El objetivo principal es determinar si la ganadería extensiva es una opción viable como método reductor de la carga combustible en los bosques de la Val...
Validation of NEPTUNE-CFD on ULPU-V experiments
Energy Technology Data Exchange (ETDEWEB)
Jamet, Mathieu, E-mail: mathieu.jamet@edf.fr; Lavieville, Jerome; Atkhen, Kresna; Mechitoua, Namane
2015-11-15
In-vessel retention (IVR) of molten corium through external cooling of the reactor pressure vessel is one possible means of severe accident mitigation for a class of nuclear power plants. The aim is to successfully terminate the progression of a core melt within the reactor vessel. The probability of success depends on the efficacy of the cooling strategy; hence one of the key aspects of an IVR demonstration relates to the heat removal capability through the vessel wall by convection and boiling in the external water flow. This is only possible if the in-vessel thermal loading is lower than the local critical heat flux expected along the outer wall of the vessel, which is in turn highly dependent on the flow characteristics between the vessel and the insulator. The NEPTUNE-CFD multiphase flow solver is used to obtain a better understanding at local scale of the thermal hydraulics involved in this situation. The validation of the NEPTUNE-CFD code on the ULPU-V facility experiments carried out at the University of California Santa Barbara is presented as a first attempt of using CFD codes at EDF to address such an issue. Two types of computation are performed. On the one hand, a steady state algorithm is used to compute natural circulation flow rates and differential pressures and, on the other, a transient algorithm computation reveals the oscillatory nature of the pressure data recorded in the ULPU facility. Several dominant frequencies are highlighted. In both cases, the CFD simulations reproduce reasonably well the experimental data for these quantities.
CFD analysis of cascade effects in marine propellers with trailing edge modification
DEFF Research Database (Denmark)
Shin, Keun Woo; Andersen, Poul
2015-01-01
investigated intensively by viscous flow solvers, although RANS CFD is prevalent in marine industry nowadays. In the current work, the cascade effect of a marine propeller is analyzed by CFD simulations on a threedimensional propeller model with varying the number of blades. The influence of trailing......-edge configurations on the cascade effect is also investigated by simulating CFD with varying trailingedge thickness and slope. The reason why the trailingedge is handled rather than other parts of bladegeometry is that it can be modified without altering overall blade thrust significantly, because the loading...
Study of Space Charge in SC Shield / XLPE Interface and Mid-Voltage Cable Perfomance
Directory of Open Access Journals (Sweden)
Idalberto Tamayo Ávila
2013-01-01
Full Text Available Se estudiaron tres cables experimentales de media tensión: C2, C3 y C4; con aislamiento de polietileno reticulado (XLPE denominados: Medio, Alto y Bajo en los test de perforación con tensiones sobre 150 kV. Los tres cables han sido medidos sistemáticamente mediante las técnicas del Pulso Electroacústico (PEA y de las Corrientes de Despolarización Estimuladas Térmicamente (TSDC usando un voltaje de polarización de 120 kV en muestras tal y como se reciben, tratadas térmicamente a 90 oC y 120 oC durante 672 horas. Las medidas de carga interna en el cable C4 son de un orden del doble que en los cables C2 y C3. El fenómeno de carga interfacial ha sido estudiado por espectroscopia infrarroja mediante la técnica de Reflectancia Total Atenuada (ATR y muestra que hay componentes que migran, se difunden y se trasportan desde la capa semiconductora externa hacia el aislamiento de polietileno reticulado durante el tratamiento térmico del cable. Las medidas por PEA usando un campo eléctrico de 120 KV/mm muestran la formación y propagación de paquetes de carga de espacio desde el semiconductor (SC hacia el aislamiento. Estos resultados son coherentes con las medidas mediante TSDC que muestran diferencias entre las áreas bajo la curva de corriente en función de la temperatura para los tres cables C2, C3 y C4 que es el resultado de la carga acumulada. Para resumir, la combinación de las mediciones PEA, TSDC y ATR son herramientas útiles para la comprensión de los procesos de relajación de carga de espacio y la eficiencia de los cables con aislamiento de XLPE.
Factores de riesgo de bajo peso al nacer en un hospital cubano, 1997-2000
Directory of Open Access Journals (Sweden)
Escobar José Andrés Cabrales
2002-01-01
Full Text Available Objetivo. Identificar qué factores de riesgo materno durante el embarazo se asocian a la incidencia de bajo peso al nacer (menos de 2 500 g. Métodos. Se diseñó un estudio de casos y testigos con 764 casos de nacimiento simple con un peso al nacer de menos de 2 500 g, y 1 437 testigos del Hospital Gineco-Obstétrico Provincial de Sancti Spíritus, Cuba, durante el cuatrienio de 1997-2000. Los datos se obtuvieron de historias clínicas, registros de partos y entrevistas personales con las madres. Se realizó un análisis con dos variables y se controlaron los posibles factores de confusión mediante regresión logística dicotómica con el programa SPSS. Se usó un modelo final de múltiples variables para identificar los factores de riesgo maternos asociados con el bajo peso al nacer. Resultados. El análisis con múltiples variables mostró una asociación significativa del bajo peso al nacer con la presencia de anemia en la madre cuando se detectó el embarazo, la sepsis urinaria durante el embarazo, el asma bronquial, un aumento de peso materno menor de 8 kg durante todo el embarazo, el hábito de fumar durante el mismo, antecedentes de bajo peso al nacer en partos anteriores, la presencia de hipertensión arterial desde antes de la gestación y la consulta prenatal extemporánea. Conclusiones. A partir de estos resultados se concluyó que, independientemente de la medida de impacto utilizada, es importante tratar de disminuir los factores de riesgo identificados a fin de reducir la incidencia del bajo peso al nacer en la provincia de Sancti Spíritus.
Factores de riesgo de bajo peso al nacer en un hospital cubano, 1997-2000
Directory of Open Access Journals (Sweden)
José Andrés Cabrales Escobar
2002-09-01
Full Text Available Objetivo. Identificar qué factores de riesgo materno durante el embarazo se asocian a la incidencia de bajo peso al nacer (menos de 2 500 g. Métodos. Se diseñó un estudio de casos y testigos con 764 casos de nacimiento simple con un peso al nacer de menos de 2 500 g, y 1 437 testigos del Hospital Gineco-Obstétrico Provincial de Sancti Spíritus, Cuba, durante el cuatrienio de 1997-2000. Los datos se obtuvieron de historias clínicas, registros de partos y entrevistas personales con las madres. Se realizó un análisis con dos variables y se controlaron los posibles factores de confusión mediante regresión logística dicotómica con el programa SPSS. Se usó un modelo final de múltiples variables para identificar los factores de riesgo maternos asociados con el bajo peso al nacer. Resultados. El análisis con múltiples variables mostró una asociación significativa del bajo peso al nacer con la presencia de anemia en la madre cuando se detectó el embarazo, la sepsis urinaria durante el embarazo, el asma bronquial, un aumento de peso materno menor de 8 kg durante todo el embarazo, el hábito de fumar durante el mismo, antecedentes de bajo peso al nacer en partos anteriores, la presencia de hipertensión arterial desde antes de la gestación y la consulta prenatal extemporánea. Conclusiones. A partir de estos resultados se concluyó que, independientemente de la medida de impacto utilizada, es importante tratar de disminuir los factores de riesgo identificados a fin de reducir la incidencia del bajo peso al nacer en la provincia de Sancti Spíritus.
Investigation of the condensing vapor bubble behavior through CFD simulation
International Nuclear Information System (INIS)
Sablania, Sidharth; Verma, Akash; Goyal, P.; Dutta, Anu; Singh, R.K.
2013-09-01
In nuclear systems the sub-cooled boiling flow is an important problem due to the behavior of condensing vapor bubble which has a large effect on the heat transfer characteristics as well as pressure drops and flow instability. The sub-cooled boiling flows become very complex and dynamic phenomena by the vapor bubble-water interaction. This happens due to the boiling/condensation, break-up, and coalescence of the bubble and needs to be addressed for characterizing the above mentioned flow parameters. There have been many researches to analyze the behavior of bubble experimentally and analytically. However, it is very difficult to get complete information about the behavior of bubble because of ever changing interface between vapor and water phase due to bubble condensation/evaporation Therefore, it is necessary to carry out a CFD simulation for better understanding the complex phenomenon of the bubble behavior. The present work focuses on the simulation of condensing bubble in subcooled boiling flow using (Volume of Fluid) VOF method in the CFD code CFD-ACE+. In order to simulate the heat and mass transfer through the bubble interface, CFD modeling for the bubble condensation was developed by modeling the source terms in the governing equations of VOF model using the User-Defined Function (UDF) in CFD-ACE+ code. The effect of condensation on bubble behavior was analyzed by comparing the behavior of condensing bubble with that of adiabatic bubble. It was observed that the behavior of condensing bubble was different from that of non condensing bubble in respect of bubble shape, diameter, velocity etc. The results obtained from the present simulation in terms of various parameters such as bubble velocity, interfacial area and bubble volume agreed well with the reported experimental results verified with FLUENT code in available literature. Hence, this CFD-ACE+ simulation of single bubble condensation will be a useful computational fluid dynamics tool for analyzing the
CFD Modeling of a Multiphase Gravity Separator Vessel
Narayan, Gautham
2017-05-23
The poster highlights a CFD study that incorporates a combined Eulerian multi-fluid multiphase and a Population Balance Model (PBM) to study the flow inside a typical multiphase gravity separator vessel (GSV) found in oil and gas industry. The simulations were performed using Ansys Fluent CFD package running on KAUST supercomputer, Shaheen. Also, a highlight of a scalability study is presented. The effect of I/O bottlenecks and using Hierarchical Data Format (HDF5) for collective and independent parallel reading of case file is presented. This work is an outcome of a research collaboration on an Aramco project on Shaheen.
CFD Modeling of a Multiphase Gravity Separator Vessel
Narayan, Gautham; Khurram, Rooh Ul Amin; Elsaadawy, Ehab
2017-01-01
The poster highlights a CFD study that incorporates a combined Eulerian multi-fluid multiphase and a Population Balance Model (PBM) to study the flow inside a typical multiphase gravity separator vessel (GSV) found in oil and gas industry. The simulations were performed using Ansys Fluent CFD package running on KAUST supercomputer, Shaheen. Also, a highlight of a scalability study is presented. The effect of I/O bottlenecks and using Hierarchical Data Format (HDF5) for collective and independent parallel reading of case file is presented. This work is an outcome of a research collaboration on an Aramco project on Shaheen.
Ovalle Izquierdo, Ingrid Nathalia; Sotelo Zalamea, Luis Daniel
2017-01-01
RESUMEN INTRODUCCIÓN En Colombia y el mundo entero el personal de transporte de carga es numeroso, y un grupo importante para la economía de cada país por su demandante trabajo, por lo que es necesario mejorar las condiciones del puesto de trabajo de los transportadores, para prevenir enfermedades o lesiones y controlar los factores de riesgo. Algunos de los riesgos que se han asociado a los conductores de carga son gases de escape, ruido por encima de los niveles permisibles, vibracion...
Directory of Open Access Journals (Sweden)
Benny Baskara
2014-02-01
Full Text Available On the one one hand, the Bajo people are well-known as ‘the sea people’ who have their own indigenous belief system – belief in the Lord of the Sea. On the other hand, they also acknowledge themselves as Muslims. Thus, the religious identity of the Bajo people reflects a unique combination of Islamic teachings and their indigenous beliefs. This unique combination is not only expressed in their religious life, in their rituals and worship practices, but also in the values found in their customary practices (adat as a guiding system for their life. This paper examines the construction and contestation of the religious identity of the Bajo people, especially how they construct their identities in relation to their natural, social, and religious environments. The contestation of the Bajo religious identity covers three aspects: the contestation of the Islam of ‘the sea people’ against the Islam of ‘the land people’, the contenstation of the ‘official’ Islam against the ‘traditional’ Islam, and the challenges of modernity, especially the commodification of the Bajo religious expressions. This contestation, in turn, reconstructs their religious identity into a more adaptive one.
Directory of Open Access Journals (Sweden)
Kamran Ghasemzadeh
2017-04-01
Full Text Available This study presents a 2D-axisymmetric computational fluid dynamic (CFD model to investigate the performance Pd membrane reactor (MR during propane dehydrogenation process for hydrogen production. The proposed CFD model provided the local information of temperature and component concentration for the driving force analysis. After investigation of mesh independency of CFD model, the validation of CFD model results was carried out by other modeling data and a good agreement between CFD model results and theoretical data was achieved. Indeed, in the present model, a tubular reactor with length of 150 mm was considered, in which the Pt-Sn-K/Al2O3 as catalyst were filled in reaction zone. Hence, the effects of the important operating parameter (reaction temperature on the performances of membrane reactor (MR were studied in terms of propane conversion and hydrogen yield. The CFD results showed that the suggested MR system during propane dehydrogenation reaction presents higher performance with respect to once obtained in the conventional reactor (CR. In particular, by applying Pd membrane, was found that propane conversion can be increased from 41% to 49%. Moreover, the highest value of propane conversion (X = 91% was reached in case of Pd-Ag MR. It was also established that the feed flow rate of the MR is to be the one of the most important factors defining efficiency of the propane dehydrogenation process.
Umeda, Yasuyuki; Ishida, Fujimaro; Tsuji, Masanori; Furukawa, Kazuhiro; Shiba, Masato; Yasuda, Ryuta; Toma, Naoki; Sakaida, Hiroshi; Suzuki, Hidenori
2017-01-01
This study aimed to predict recurrence after coil embolization of unruptured cerebral aneurysms with computational fluid dynamics (CFD) using porous media modeling (porous media CFD). A total of 37 unruptured cerebral aneurysms treated with coiling were analyzed using follow-up angiograms, simulated CFD prior to coiling (control CFD), and porous media CFD. Coiled aneurysms were classified into stable or recurrence groups according to follow-up angiogram findings. Morphological parameters, coil packing density, and hemodynamic variables were evaluated for their correlations with aneurysmal recurrence. We also calculated residual flow volumes (RFVs), a novel hemodynamic parameter used to quantify the residual aneurysm volume after simulated coiling, which has a mean fluid domain > 1.0 cm/s. Follow-up angiograms showed 24 aneurysms in the stable group and 13 in the recurrence group. Mann-Whitney U test demonstrated that maximum size, dome volume, neck width, neck area, and coil packing density were significantly different between the two groups (P CFD and larger RFVs in the porous media CFD. Multivariate logistic regression analyses demonstrated that RFV was the only independently significant factor (odds ratio, 1.06; 95% confidence interval, 1.01-1.11; P = 0.016). The study findings suggest that RFV collected under porous media modeling predicts the recurrence of coiled aneurysms.
Perfil cognitivo de niños con rendimientos bajos en comprensión lectora
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Lorena Canet-Juric
2013-10-01
Full Text Available La mayoría de los niños con dificultades en la comprensión lectora poseen rendimientos inferiores en un conjunto de procesos cognitivos. El objetivo del presente estudio es establecer un perfil cognitivo asociado al bajo rendimiento en comprensión lectora en relación a la habilidad de monitoreo, a la producción de inferencias, al vocabulario, a la amplitud de memoria de trabajo y a la capacidad inhibitoria, en niños hispanoparlantes. Para ello se administraron tareas correspondientes a dichos procesos en niños con altos y bajos rendimientos en comprensión lectora. Los resultados mostraron que si bien los niños con mala comprensión presentan bajos rendimientos en estas habilidades, no puede establecerse un perfil consistente ya que hay niños con problemas en comprensión que presentan normal o superior rendimiento en algunas de estas habilidades cognitivas.
Lack of association of CFD polymorphisms with advanced age-related macular degeneration.
Zeng, Jiexi; Chen, Yuhong; Tong, Zongzhong; Zhou, Xinrong; Zhao, Chao; Wang, Kevin; Hughes, Guy; Kasuga, Daniel; Bedell, Matthew; Lee, Clara; Ferreyra, Henry; Kozak, Igor; Haw, Weldon; Guan, Jean; Shaw, Robert; Stevenson, William; Weishaar, Paul D; Nelson, Mark H; Tang, Luosheng; Zhang, Kang
2010-11-03
Age-related macular degeneration (AMD) is the most common cause of irreversible central vision loss worldwide. Research has linked AMD susceptibility with dysregulation of the complement cascade. Typically, complement factor H (CFH), complement factor B (CFB), complement component 2 (C2), and complement component 3 (C3) are associated with AMD. In this paper, we investigated the association between complement factor D (CFD), another factor of the complement system, and advanced AMD in a Caucasian population. Six single nucleotide polymorphisms (SNPs), rs1683564, rs35186399, rs1683563, rs3826945, rs34337649, and rs1651896, across the region covering CFD, were chosen for this study. One hundred and seventy-eight patients with advanced AMD and 161 age-matched normal controls were genotyped. Potential positive signals were further tested in another independent 445 advanced AMD patients and 190 controls. χ2 tests were performed to compare the allele frequencies between case and control groups. None of the six SNPs of CFD was found to be significantly associated with advanced AMD in our study. Our findings suggest that CFD may not play a major role in the genetic susceptibility to AMD because no association was found between the six SNPs analyzed in the CFD region and advanced AMD.
Determinación de la presencia de fatiga mecánica en materiales cerámicos
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Casellas, D.
1999-04-01
Full Text Available It is well known that ceramic materials are highly susceptible to environmental assisted subcritical crack growth. In addition, this subcritical crack growth could be also related to cyclic loading (mechanical fatigue. This type of behaviour is not observed either in glasses nor in traditional ceramics. However this phenomena is clearly active in many advanced ceramics. The aim of this work is to obtain a procedure for detecting the presence of cyclic fatigue in ceramic materials. This procedure attempts to obtain cyclic fatigue life estimations and to compare it with the static loading experimental results. Through this comparisons it is possible to asses whether the cyclic fatigue is acting or not. Finally some calculations are conducted in ceramic materials (alumina, mullite and ZTA with natural and indentation flaws.
Los materiales cerámicos son susceptibles al crecimiento de fisuras por la acción combinada del medio ambiente y la aplicación de carga (fatiga estática. Por otra parte, el crecimiento subcrítico de fisuras en cerámicas también puede ser producido por la aplicación de cargas fluctuantes (fatiga mecánica. Este fenómeno no se observa en vidrios ni en cerámicas monocristalinas, pero si en muchos de los llamados materiales cerámicos avanzados. En este trabajo se describe una metodología utilizada para detectar la presencia de fatiga mecánica en materiales cerámicos, basada en la obtención de estimaciones de la vida a fatiga del material bajo cargas fluctuantes y su comparación con los resultados experimentales bajo carga constante. Este método se ha aplicado a fisuras naturales y de indentación en algunos materiales cerámicos (mullita, alúmina y ZTA.
An Eulerian-Eulerian CFD Simulation of Air-Water Flow in a Pipe Separator
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E.A. Afolabi
2014-06-01
Full Text Available This paper presents a three dimensional Computational Fluid Dynamics (CFD of air-water flow using Eulerian –Eulerian multiphase model and RSM mixture turbulence model to investigate its hydrodynamic flow behaviour in a 30 mm pipe separator. The simulated results are then compared with the stereoscopic PIV measurements at different axial positions. The comparison shows that the velocity distribution can be predicted with high accuracy using CFD. The numerical velocity profiles are also found to be in good qualitative agreement with the experimental measurements. However, there were some discrepancies between the CFD results and the SPIV measurements at some axial positions away from the inlet section. Therefore, the CFD model could provide good physical understanding on the hydrodynamics flow behaviour for air-water in a pipe separator.
CFD-based design load analysis of 5MW offshore wind turbine
Tran, T. T.; Ryu, G. J.; Kim, Y. H.; Kim, D. H.
2012-11-01
The structure and aerodynamic loads acting on NREL 5MW reference wind turbine blade are calculated and analyzed based on advanced Computational Fluid Dynamics (CFD) and unsteady Blade Element Momentum (BEM). A detailed examination of the six force components has been carried out (three force components and three moment components). Structure load (gravity and inertia load) and aerodynamic load have been obtained by additional structural calculations (CFD or BEM, respectively,). In CFD method, the Reynolds Average Navier-Stokes approach was applied to solve the continuity equation of mass conservation and momentum balance so that the complex flow around wind turbines was modeled. Written in C programming language, a User Defined Function (UDF) code which defines transient velocity profile according to the Extreme Operating Gust condition was compiled into commercial FLUENT package. Furthermore, the unsteady BEM with 3D stall model has also adopted to investigate load components on wind turbine rotor. The present study introduces a comparison between advanced CFD and unsteady BEM for determining load on wind turbine rotor. Results indicate that there are good agreements between both present methods. It is importantly shown that six load components on wind turbine rotor is significant effect under Extreme Operating Gust (EOG) condition. Using advanced CFD and additional structural calculations, this study has succeeded to construct accuracy numerical methodology to estimate total load of wind turbine that compose of aerodynamic load and structure load.
La carga física de los trabajadores: estrategia administrativa en la mejora de procesos
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Grether Lucía Real Pérez
2015-06-01
Full Text Available La administración surge cuando existe la necesidad de manejar recursos. Los administradores deben planificar, organizar, dirigir y controlar todos los elementos de los procesos, considerando los medios de trabajo, los objetos de trabajo y las personas. Este último es el eslabón fundamental del proceso productivo o de servicio. Se debe considerar además el entorno y su relación con el medio ambiente, permitiendo ser a las empresas responsables con los tres pilares fundamentales: la sociedad, el medio ambiente, y la economía. La Ergonomía, como ciencia aplicada, permite garantizar las condiciones de seguridad, salud y bienestar a sus trabajadores, logrando ser más productivos, eficientes, eficaces y competitivos. El objetivo de la investigación fue conocer las implicaciones de la carga física en los trabajadores, utilizando una herramienta de diagnóstico que permitió, como resultado fundamental, el establecimiento de programas de mejoras ajustados a cada una de las realidades de los puestos de trabajo. Palabras clave: Ergonomía, Administración, Carga física, Factores de riesgo, Programa de mejoras
International Nuclear Information System (INIS)
Lee, Sumi; Song, Doosam
2010-01-01
Drastic urbanization and manhattanization are causing various problems in wind environment. This study suggests a CFD simulation method to evaluate wind environment in the early design stage of high-rise buildings. The CFD simulation of this study is not a traditional in-depth simulation, but a method to immediately evaluate wind environment for each design alternative and provide guidelines for design modification. Thus, the CFD simulation of this study to evaluate wind environments uses BIM-based CFD tools to utilize building models in the design stage. This study examined previous criteria to evaluate wind environment for pedestrians around buildings and selected evaluation criteria applicable to the CFD simulation method of this study. Furthermore, proper mesh generation method and CPU time were reviewed to find a meaningful CFD simulation result for determining optimal design alternative from the perspective of wind environment in the design stage. In addition, this study is to suggest a wind environment evaluation method through a BIM-based CFD simulation.
AP-IO: asynchronous pipeline I/O for hiding periodic output cost in CFD simulation.
Xiaoguang, Ren; Xinhai, Xu
2014-01-01
Computational fluid dynamics (CFD) simulation often needs to periodically output intermediate results to files in the form of snapshots for visualization or restart, which seriously impacts the performance. In this paper, we present asynchronous pipeline I/O (AP-IO) optimization scheme for the periodically snapshot output on the basis of asynchronous I/O and CFD application characteristics. In AP-IO, dedicated background I/O processes or threads are in charge of handling the file write in pipeline mode, therefore the write overhead can be hidden with more calculation than classic asynchronous I/O. We design the framework of AP-IO and implement it in OpenFOAM, providing CFD users with a user-friendly interface. Experimental results on the Tianhe-2 supercomputer demonstrate that AP-IO can achieve a good optimization effect for the periodical snapshot output in CFD application, and the effect is especially better for massively parallel CFD simulations, which can reduce the total execution time up to about 40%.
AP-IO: Asynchronous Pipeline I/O for Hiding Periodic Output Cost in CFD Simulation
Directory of Open Access Journals (Sweden)
Ren Xiaoguang
2014-01-01
Full Text Available Computational fluid dynamics (CFD simulation often needs to periodically output intermediate results to files in the form of snapshots for visualization or restart, which seriously impacts the performance. In this paper, we present asynchronous pipeline I/O (AP-IO optimization scheme for the periodically snapshot output on the basis of asynchronous I/O and CFD application characteristics. In AP-IO, dedicated background I/O processes or threads are in charge of handling the file write in pipeline mode, therefore the write overhead can be hidden with more calculation than classic asynchronous I/O. We design the framework of AP-IO and implement it in OpenFOAM, providing CFD users with a user-friendly interface. Experimental results on the Tianhe-2 supercomputer demonstrate that AP-IO can achieve a good optimization effect for the periodical snapshot output in CFD application, and the effect is especially better for massively parallel CFD simulations, which can reduce the total execution time up to about 40%.
Anderson, Kevin R.; Zayas, Daniel; Turner, Daniel
2012-01-01
Computational Fluid Dynamics (CFD) using the commercial CFD package CFDesign has been performed at NASA Jet Propulsion Laboratory (JPL) California Institute of Technology (Caltech) in support of the Phaeton Early Career Hire Program's Optical Payload for Lasercomm Science (OPALS) mission. The OPALS project is one which involves an International Space Station payload that will be using forced convection cooling in a hermetically sealed enclosure at 1 atm of air to cool "off-the-shelf" vendor electronics. The CFD analysis was used to characterize the thermal and fluid flow environment within a complicated labyrinth of electronics boards, fans, instrumentation, harnessing, ductwork and heat exchanger fins. The paradigm of iteratively using CAD/CAE tools and CFD was followed in order to determine the optimum flow geometry and heat sink configuration to yield operational convective film coefficients and temperature survivability limits for the electronics payload. Results from this current CFD analysis and correlation of the CFD model against thermal test data will be presented. Lessons learned and coupled thermal / flow modeling strategies will be shared in this paper.
CFD analysis for offshore systems: validation and applications
Energy Technology Data Exchange (ETDEWEB)
Silva, Daniel Fonseca de Carvalho e; Pagot, Paulo Roberto [Centro de Pesquisas da PETROBRAS (CENPES), Rio de janeiro, RJ (Brazil). Gerencia de Tecnologia de Engenharia Oceanica], E-mails: danielfc@petrobras.com.br, pagot@petrobras.com.br
2011-04-15
The Ocean Engineering group in the PETROBRAS Research Center develops and applies multidisciplinary simulation tools for several engineering problems mainly related to offshore systems. Recently, there have been many different cases where Computational Fluid Dynamics (CFD) has been successfully employed. This study presents a collection of cases where CFD simulations were validated against experimental data and directly used to facilitate solutions for practical problems. Case 01 calculated the maritime current loads on an FPSO and investigated the influence of appendices such as bilge keels and rudders on the near flow field. Similarly, Case 02 extends this procedure to the identification of wind loads. Case 03 calculates the hydrodynamic forces on a torpedo anchor during its installation. The simulation results coupled with a simplified dynamic model facilitates the directional stability of different torpedo models to be evaluated. A whole FPSO topside geometry is modeled in Case 04, which investigates the flow pattern near the FPSO Helideck. The simulation velocity and turbulence profiles were compared to wind tunnel measurements. These summarized cases show how CFD tools can be advantageously applied to solve many practical problems. All these simulations were performed using ANSYS CFX. (author)
International Nuclear Information System (INIS)
Visser, D.C.; Siccama, N.B.; Jayaraju, S.T.; Komen, E.M.J.
2014-01-01
Highlights: • A CFD based model developed in ANSYS-FLUENT for simulating the distribution of hydrogen in the containment of a nuclear power plant during a severe accident is validated against four large-scale experiments. • The successive formation and mixing of a stratified gas-layer in experiments performed in the THAI and PANDA facilities are predicted well by the CFD model. • The pressure evolution and related condensation rate during different mixed convection flow conditions in the TOSQAN facility are predicted well by the CFD model. • The results give confidence in the general applicability of the CFD model and model settings. - Abstract: In the event of core degradation during a severe accident in water-cooled nuclear power plants (NPPs), large amounts of hydrogen are generated that may be released into the reactor containment. As the hydrogen mixes with the air in the containment, it can form a flammable mixture. Upon ignition it can damage relevant safety systems and put the integrity of the containment at risk. Despite the installation of mitigation measures, it has been recognized that the temporary existence of combustible or explosive gas clouds cannot be fully excluded during certain postulated accident scenarios. The distribution of hydrogen in the containment and mitigation of the risk are, therefore, important safety issues for NPPs. Complementary to lumped parameter code modelling, Computational Fluid Dynamics (CFD) modelling is needed for the detailed assessment of the hydrogen risk in the containment and for the optimal design of hydrogen mitigation systems in order to reduce this risk as far as possible. The CFD model applied by NRG makes use of the well-developed basic features of the commercial CFD package ANSYS-FLUENT. This general purpose CFD package is complemented with specific user-defined sub-models required to capture the relevant thermal-hydraulic phenomena in the containment during a severe accident as well as the effect of
Energy Technology Data Exchange (ETDEWEB)
Visser, D.C., E-mail: visser@nrg.eu; Siccama, N.B.; Jayaraju, S.T.; Komen, E.M.J.
2014-10-15
Highlights: • A CFD based model developed in ANSYS-FLUENT for simulating the distribution of hydrogen in the containment of a nuclear power plant during a severe accident is validated against four large-scale experiments. • The successive formation and mixing of a stratified gas-layer in experiments performed in the THAI and PANDA facilities are predicted well by the CFD model. • The pressure evolution and related condensation rate during different mixed convection flow conditions in the TOSQAN facility are predicted well by the CFD model. • The results give confidence in the general applicability of the CFD model and model settings. - Abstract: In the event of core degradation during a severe accident in water-cooled nuclear power plants (NPPs), large amounts of hydrogen are generated that may be released into the reactor containment. As the hydrogen mixes with the air in the containment, it can form a flammable mixture. Upon ignition it can damage relevant safety systems and put the integrity of the containment at risk. Despite the installation of mitigation measures, it has been recognized that the temporary existence of combustible or explosive gas clouds cannot be fully excluded during certain postulated accident scenarios. The distribution of hydrogen in the containment and mitigation of the risk are, therefore, important safety issues for NPPs. Complementary to lumped parameter code modelling, Computational Fluid Dynamics (CFD) modelling is needed for the detailed assessment of the hydrogen risk in the containment and for the optimal design of hydrogen mitigation systems in order to reduce this risk as far as possible. The CFD model applied by NRG makes use of the well-developed basic features of the commercial CFD package ANSYS-FLUENT. This general purpose CFD package is complemented with specific user-defined sub-models required to capture the relevant thermal-hydraulic phenomena in the containment during a severe accident as well as the effect of
CFD simulation of solids suspension in stirred tanks: Review
Directory of Open Access Journals (Sweden)
Ochieng Aoyi
2010-01-01
Full Text Available Many chemical reactions are carried out using stirred tanks, and the efficiency of such systems depends on the quality of mixing, which has been a subject of research for many years. For solid-liquid mixing, traditionally the research efforts were geared towards determining mixing features such as off-bottom solid suspension using experimental techniques. In a few studies that focused on the determination of solids concentration distribution, some methods that have been used have not been accurate enough to account for some small scale flow mal-distribution such as the existence of dead zones. The present review shows that computational fluid dynamic (CFD techniques can be used to simulate mixing features such as solids off-bottom suspension, solids concentration and particle size distribution and cloud height. Information on the effects of particle size and particle size distribution on the solids concentration distribution is still scarce. Advancement of the CFD modeling is towards coupling the physical and kinetic data to capture mixing and reaction at meso- and micro-scales. Solids residence time distribution is important for the design; however, the current CFD models do not predict this parameter. Some advances have been made in recent years to apply CFD simulation to systems that involve fermentation and anaerobic processes. In these systems, complex interaction between the biochemical process and the hydrodynamics is still not well understood. This is one of the areas that still need more attention.
CFD thermal-hydraulic analysis of a CANDU fuel channel
International Nuclear Information System (INIS)
Catana, A.; Prisecaru, I.; Dupleac, D.; Danila, N.
2009-01-01
This paper presents the numerical investigation of a CANDU fuel channel using CFD (Computational fluid dynamics) methodology approach. Limited computer power available at Bucharest University POLITEHNICA forced the authors to analyse only segments of fuel channel namely the significant ones: fuel bundle junctions with adjacent segments, fuel bundle spacer planes with adjacent segments, regular segments of fuel bundles. The computer code used is FLUENT. Fuel bundles contained in pressure tubes forms a complex flow domain. The flow is characterized by high turbulence and in some parts of fuel channel also by multi-phase flow. The flow in the fuel channel has been simulated by solving the equations for conservation of mass and momentum. For turbulence modelling the standard k-e model is employed although other turbulence models can be used as well. In this paper we do not consider heat generation and heat transfer capabilities of CFD methods. Since we consider only some relatively short segments of a CANDU fuel channel we can assume, for this starting stage, that heat transfer is not very important for these short segments of fuel channel. The boundary conditions for CFD analysis are provided by system and sub-channel analysis. In this paper the discussion is focused on some flow parameters behaviour at the bundle junction, spacer's plane configuration, etc. In this paper we present results for Standard CANDU 6 Fuel Bundles as a basis for CFD thermal-hydraulic analysis of INR proposed SEU43 and other new nuclear fuels. (authors)
CFD simulations for engine intake manifolds
International Nuclear Information System (INIS)
Witry, A.; Zhao, A.
2002-01-01
This paper attempts to explain a procedure for using Computational Fluid Dynamics (CFD) for product development of engine intake manifolds. The paper uses the development of an intake manifold as an example of such a process. Using the commercial FLUENT solver, its standard wall functions and k-ε model, a four runner intake manifold with an average mesh size of 300, 000 hexa elements created in ICEM-CFD with a maximum skewness of 0.85 produces rapid results for quick product turn-around times. The setup used allows for compressibility and viscous heating effects to be modeled whilst ignoring wall heat transfer due to the high speeds of the air/foil mixture and low residence times. Eight consecutive models were modeled here whilst carrying out continuous enhancements. For every iteration, four different so called 'static' runs with only one runner open at any one time using a steady state assumption were calculated further assuming that only one intake valve is open at any one time. Even flow distributions between the runner are deemed to be 'dynamically' obtained once the pressure drops between the manifold's inlet and runner outlets are equalized. Furthermore, different modifications were attempted to ensure that the fluid's particle tracks show very little particle return tendencies along with excellent nonuniformity indexes at the runners outlets. Confirmation of these results were obtained from test data showing CFD pressure drop predictions to be within 4% error with 67% of any runner's pressure losses being caused in the runner itself due to the small cross sectional area(s). (author)
Multiphase CFD simulation of a solid bowl centrifuge
Energy Technology Data Exchange (ETDEWEB)
Romani Fernandez, X.; Nirschl, H. [Universitaet Karlsruhe, Institut fuer MVM, Karlsruhe (Germany)
2009-05-15
This study presents some results from the numerical simulation of the flow in an industrial solid bowl centrifuge used for particle separation in industrial fluid processing. The computational fluid dynamics (CFD) software Fluent was used to simulate this multiphase flow. Simplified two-dimensional and three-dimensional geometries were built and meshed from the real centrifuge geometry. The CFD results show a boundary layer of axially fast moving fluid at the gas-liquid interface. Below this layer there is a thin recirculation. The obtained tangential velocity values are lower than the ones for the rigid-body motion. Also, the trajectories of the solid particles are evaluated. (Abstract Copyright [2009], Wiley Periodicals, Inc.)
CFD Modelling in Screw Compressors With Complex Multi Rotor Configurations
Rane, Sham Ramchandra; Kovacevic, Ahmed; Kethidi, Madhulika
2012-01-01
Computational Fluid Dynamics (CFD) of screw compressors is challenging due to the positive displacement nature of the process, existence of very fine fluid leakage paths, coexistence of working fluid and lubricant or coolant, fluid injection and most importantly the lack of methodologies available to generate meshes required for the full three dimensional transient simulations. In this paper, currently available technology of grid remeshing has been used to demonstrate the CFD simulations of ...
International Nuclear Information System (INIS)
Park, Jong Hark; Chae, H. T.; Park, C.; Kim, H.
2006-12-01
A test facility had been established for the experiment of velocity distribution and pressure drop in a tubular fuel. A basic test had been conducted to examine the performance of the test loop and to verify the accuracy of measurement by pitot-tube. In this report, test results and CFD analysis for the hydraulic characteristics of a tubular fuel, following the previous tests, are described. Coolant velocities in all channels were measured using pitot-tube and the effect of flow rate change on the velocity distribution was also examined. The pressure drop through the tubular fuel was measured for various flow rates in range of 1 kg/s to 21 kg/s to obtain a correlation of pressure drop with variation of flow rate. In addition, a CFD(Computational Fluid Dynamics) analysis was also done to find out the hydraulic characteristics of tubular fuel such as velocity distribution and pressure drop. As the results of CFD analysis can give us a detail insight on coolant flow in the tubular fuel, the CFD method is a very useful tool to understand the flow structure and phenomena induced by fluid flow. The CFX-10, a commercial CFD code, was used in this study. The two results by the experiment and the CFD analysis were investigated and compared with each other. Overall trend of velocity distribution by CFD analysis was somewhat different from that of experiment, but it would be reasonable considering measurement uncertainties. The CFD prediction for pressure drop of a tubular fuel shows a tolerably good agreement with experiment within 8% difference
International Nuclear Information System (INIS)
Gera, B.; Singh, R.K.; Vaze, K.K.
2014-01-01
Premixed hydrogen/air combustion in an upright, rectangular shaped combustion chamber has been performed numerically using commercial CFD code CFD-ACE+. The combustion chamber had dimensions 1 m X 0.024 m X 1 m. Simulations were carried out for 10% (v/v) hydrogen concentration for which experimental results were available. Effect of different boundary condition and ignition position on flame propagation was studied. Time dependent flame propagation in the chamber was predicted by CFD code. The computed transient flame propagation in the chamber was in good agreement with experimental results. The present work demonstrated that the available commercial CFD codes are capable of modeling hydrogen deflagration in a realistic manner. (author)
Application of CFD based wave loads in aeroelastic calculations
DEFF Research Database (Denmark)
Schløer, Signe; Paulsen, Bo Terp; Bredmose, Henrik
2014-01-01
Two fully nonlinear irregular wave realizations with different significant wave heights are considered. The wave realizations are both calculated in the potential flow solver Ocean-Wave3D and in a coupled domain decomposed potential-flow CFD solver. The surface elevations of the calculated wave...... domain decomposed potentialflow CFD solver result in different dynamic forces in the tower and monopile, despite that the static forces on a fixed monopile are similar. The changes are due to differences in the force profiles and wave steepness in the two solvers. The results indicate that an accurate...
International Nuclear Information System (INIS)
Green, J; Mishra, R; Charlton, M; Owen, R
2012-01-01
This study uses the experimental flow test data to validate CFD simulations for a complex control valve trim. In both the simulation and the experimental flow test the capacity of the trim (Cv) is calculated in order to test the ability of CFD software to provide a design tool for these trims. While CFD tests produced results for the capacity which were consistent across a series of five different simulations, it differed from the experimental flow data by nearly 25%. This indicates that CFD simulations need to be properly calibrated before being used in designing complex valve trims.
Directory of Open Access Journals (Sweden)
Ferrán Catalá López
2009-01-01
Conclusiones: Se observa la existencia de una asociación positiva moderada-alta de las medidas de carga de enfermedad con la financiación de la investigación, si bien existen categorías de enfermedad sobre- o infrafinanciadas en relación con la carga que provocan. En planificación sanitaria, la carga de enfermedad aporta información útil a los debates sobre establecimiento de prioridades en investigación.
ARC Code TI: CFD Utility Software Library
National Aeronautics and Space Administration — The CFD Utility Software Library consists of nearly 30 libraries of Fortran 90 and 77 subroutines and almost 100 applications built on those libraries. Many of the...
PIV, radiotracers and CFD for flow anomalies
International Nuclear Information System (INIS)
Houdek, P.; Reitspiesova, I.; Zitny, R.; Thyn, J.
2004-01-01
Experimental investigation of flow asymmetries in continuous direct ohmic heater by using PIV and stimulus response technique (radioisotope 99 Tc) is presented together with CFD modelling by using finite element code FEMINA. (author)
TRATAMIENTO POR FERMENTACIÓN ANAEROBIA DE LAS VINAZAS PRODUCIDAS EN LA FABRICACIÓN DE ALCOHOL
Directory of Open Access Journals (Sweden)
A. M. Belalcazar de Galvis
2010-10-01
Full Text Available Con el fin de disminuir su carga contaminante, las vinazas se sometieron a tratamiento en cuatro reactores tipo filtro anaerobio de flujo ascendente, los cuales se evaluaron bajo diferentes condiciones de tiempo de retención hidráulico TRH y de carga orgánica. Para una Demanda Química de Oxígeno DQO, afluente de 5000 a 30000 mg/1 y TRH de 3.0 días o más, se obtuvieron eficiencias de remoción superiores a 90% en términos de DQO. Para una DQO afluente constante de 20000 mg/1 y TRH de 1.3 días, se alcanzaron eficiencias entre 75-80%.
CFD analysis of heat transfer in a vertical annular gas gap
International Nuclear Information System (INIS)
Borgohain, A.; Maheshwari, N.K.; Vijayan, P.K.
2011-01-01
Heat transfer analysis in a vertical annulus is carried out by using a CFD code TRIO-U. The results are used to understand heat transfer in the vertical annulus. An experimental study is taken from literature for the CFD analysis. The geometry of the test section of the experiment is simulated in TRIO-U. The operating conditions of the experiment are simulated by imposing appropriate boundary conditions. Three modes of the heat transfer, conduction, radiation and convection in the gas gap are considered in the analysis. From the analysis it is found that TRIO-U can successfully handle all modes heat transfer. The theoretical results for heat transfer have been compared with experimental data. This paper deals with the detailed CFD modelling and analysis. (author)
Energy Technology Data Exchange (ETDEWEB)
Batet, L.; Mas de les Valls, E.; Sedano, L. A.
2012-07-01
In the context of regenerating sheaths for fusion reactors, the CFD simulations of liquid metal channels (ML) are essential to know the phenomenology and obtain relevant information for design as: ML thermal gain, to know the thermal efficiency of the component, existence of hot spots, to define the materials to use, existence of flow inversion, etc. Apart from design parameters there are others, bridge parameter, required as inputs into system code. In this work shown GREENER/T4F capabilities for obtaining both parameters with a CFD tool based on open source OpenFOAM.
Algoritmo para el cálculo de cargas de trabajo
Directory of Open Access Journals (Sweden)
Mauricio Becerra Fernández
2016-04-01
Full Text Available Este artículo presenta el desarrollo un algoritmo para el cálculo de cargas de trabajo, soportado en el análisis de estudios similares y la teoría del estudio de métodos y tiempos. El algoritmo se propone como un elemento de soporte para el análisis del nivel trabajo asignado a un cargo específico o a un grupo de trabajadores en un área determinada, ya sea en la industria de manufactura o de servicios, lo que permita nivelar el volumen de trabajo asignado mediante la definición de diversas alternativas que promuevan el aumento de la productividad, favorezcan la mejora en el clima y las condiciones laborales.
Aeroelastic Stability of Suspension Bridges using CFD
DEFF Research Database (Denmark)
Stærdahl, Jesper Winther; Sørensen, Niels; Nielsen, Søren R.K.
2007-01-01
using CFD models and the aeroelastic stability boundary has been successfully determined when comparing two-dimensional flow situations using wind tunnel test data and CFD methods for the flow solution and two-degrees-of-freedom structural models in translation perpendicular to the flow direction......In recent years large span suspension bridges with very thin and slender profiles have been built without proportional increasing torsional and bending stiffness. As a consequence large deformations at the mid-span can occur with risk of aeroelastic instability and structural failure. Analysis...... of aeroelastic stability also named flutter stability is mostly based on semi-empirical engineering models, where model specific parameters, the so-called flutter derivatives, need calibration from wind tunnel tests or numerical methods. Several papers have been written about calibration of flutter derivatives...
Profile and disease burden of gastric cancer patients undergoing gastrectomy
Directory of Open Access Journals (Sweden)
Gloria Mabel Carrillo
2018-01-01
Full Text Available Introducción. Los tratamientos quirúrgicos del cáncer gástrico implican adaptaciones a un nuevo estilo de vida ligado a la limitación que pueden ocasionar carga. Objetivos. Determinar el perfil y la carga de adultos con cáncer gástrico que han sido sometidos a gastrectomía en una institución de oncología en Bogotá. Materiales y métodos. Estudio de abordaje cuantitativo y corte transversal que incluyó 60 pacientes con cáncer gástrico posgastrectomía, en su mayoría hombres de estratos socioeconómicos bajos y mínimos niveles de escolaridad, con una edad promedio de 56.33 años. Se utilizó una encuesta de caracterización y el instrumento carga de la enfermedad para el paciente. Resultados. Predomina el adenocarcinoma gástrico intestinal avanzado y la gastrectomía total como cirugía de elección que genera mayor carga. Se identifica alta carga emocional por angustia, tristeza e incertidumbre y baja carga física por síntomas como molestias gastrointestinales, agotamiento y debilidad. Las dificultades económicas y la alteración del rol laboral generan carga sociofamiliar y cultural. Hay relación inversa y estadísticamente significativa entre el estado funcional del paciente y el agotamiento, la fatiga, la alteración del equilibrio y las alteraciones del sueño. Conclusiones. Los sobrevivientes de cáncer gástrico posgrastectomía presentan carga emocional, sociofamiliar y cultural que requiere ser atendida.
Demonstration of Hybrid DSMC-CFD Capability for Nonequilibrium Reacting Flow
2018-02-09
AFRL-RV-PS- TR-2018-0056 AFRL-RV-PS- TR-2018-0056 DEMONSTRATION OF HYBRID DSMC-CFD CAPABILITY FOR NONEQUILIBRIUM REACTING FLOW Thomas E...4. TITLE AND SUBTITLE Demonstration of Hybrid DSMC-CFD Capability for Nonequilibrium Reacting Flow 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA9453-17-1...simulation codes. The models are based on new ab-intio rate data obtained using state -of-the-art potential energy surfaces for air species. A probability
Factores nutricionales maternos y el bajo peso al nacer en un área de salud
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Arley Rey Vilchez
2013-01-01
Full Text Available Fundamento: el bajo peso al nacer es multifactorial y se atribuye a causas maternas, fetales y ambientales. Los hábitos alimentarios inadecuados unidos a otros factores nutricionales maternos son determinantes. Objetivo: identificar los factores nutricionales maternos relacionados con el bajo peso al nacer en pacientes del Área I del municipio Cienfuegos. Métodos: se realizó un estudio analítico, retrospectivo, de casos y controles entre enero 2006 y diciembre 2008. Se estudiaron 50 madres de recién nacidos bajo peso (casos y 100 madres de niños normopesos (controles a razón de 2 por cada caso, seleccionadas del registro de nacimientos del área. Se revisaron las historias clínicas obstétricas y se entrevistó a cada paciente para evaluar sus hábitos alimentarios según frecuencia de comidas y grupos de alimentos consumidos. El procesamiento de la información se realizó utilizando el programa estadístico SPSS versión 15,0. Los resultados se presentaron en tablas con frecuencias absolutas, porcentajes y resultados de las técnicas estadísticas empleadas. Resultados: se comportaron como factores de riesgo: la edad materna, el estado nutricional al inicio del embarazo, la ganancia de peso durante la gestación y la hemoglobina del tercer trimestre. Las mujeres con hábitos alimentarios inestables e insuficientes tuvieron 33 veces más probabilidades de tener neonatos bajo peso y las que refirieron dietas no saludables según grupos de alimentos consumidos tuvieron 9 veces más riesgo. Conclusiones: los factores nutricionales maternos influyeron en la incidencia del bajo peso al nacer, fundamentalmente los hábitos alimentarios inadecuados.
CFD simulation on Kappel propeller with a hull wake field
DEFF Research Database (Denmark)
Shin, Keun Woo; Andersen, Poul; Møller Bering, Rasmus
2013-01-01
Marine propellers are designed not for the open-water operation, but for the operation behind a hull due to the inhomogeneous hull wake and thrust deduction. The adaptation for the hull wake is important for the propulsive efficiency and cavitation risk especially on single-screw ships. CFD...... simulations for a propeller with a hull model have showed acceptable agreement with a model test result in the thrust and torque (Larsson et al. 2010). In the current work, a measured hull wake is applied to the simulation instead of modelling a hull, because the hull geometry is mostly not available...... for propeller designers and the computational effort can be reduced by excluding the hull. The CFD simulation of a propeller flow with a hull wake is verified in order to use CFD as a propeller design tool. A Kappel propeller, which is an innovative tip-modified propeller, is handled. Kappel propellers...
CFD analysis of ejector in a combined ejector cooling system
Energy Technology Data Exchange (ETDEWEB)
Rusly, E.; Aye, Lu [International Technologies Centre (IDTC), Department of Civil and Environmental Engineering, The University of Melbourne, Melbourne, Vic. 3010 (Australia); Charters, W.W.S.; Ooi, A. [Department of Mechanical and Manufacturing Engineering, The University of Melbourne, Melbourne, Vic. 3010 (Australia)
2005-11-01
One-dimensional ejector analyses often use coefficients derived from experimental data for a set of operating conditions with limited functionality. In this study, several ejector designs were modelled using finite volume CFD techniques to resolve the flow dynamics in the ejectors. The CFD results were validated with available experimental data. Flow field analyses and predictions of ejector performance outside the experimental range were also carried out. During validation, data from CFD predicted the entrainment ratios with greater accuracy on definite area ratios, although no shock was recorded in the ejector. Predictions outside the experimental range-at operating conditions in a combined ejector-vapour compression system-and flow conditions resulting from ejector geometry variations are discussed. It is found that the maximum entrainment ratio happens in the ejector just before a shock occurs and that the position of the nozzle is an important ejector design parameter. (author)
Partitioned Fluid-Structure Interaction for Full Rotor Computations Using CFD
DEFF Research Database (Denmark)
Heinz, Joachim Christian
) based aerodynamic model which is computationally cheap but includes several limitations and corrections in order to account for three-dimensional and unsteady eects. The present work discusses the development of an aero-elastic simulation tool where high-fidelity computational fluid dynamics (CFD......) is used to model the aerodynamics of the flexible wind turbine rotor. Respective CFD computations are computationally expensive but do not show the limitations of the BEM-based models. It is one of the first times that high-fidelity fluid-structure interaction (FSI) simulations are used to model the aero......-elastic response of an entire wind turbine rotor. The work employs a partitioned FSI coupling between the multi-body-based structural model of the aero-elastic solver HAWC2 and the finite volume CFD solver EllipSys3D. In order to establish an FSI coupling of sufficient time accuracy and sufficient numerical...
CFD aspects of ADSS target design
International Nuclear Information System (INIS)
Shashi Kumar, G.N.; Mahendra, A.K.; Sanyal, A.; Gouthaman, G.
2004-03-01
The preliminary studies on CFD aspects of Accelerator Driven Sub-critical System (ADSS) target design has been presented in this report. The studies involve the thermal hydraulic analysis of the Liquid Metal Spallation Target (LMST) using Lead Bismuth Eutectic (LBE) as the target material. Apart from acting as Spallation medium LBE is used to remove the heat deposited by High Energy Proton Beam. Window of the target ( one side vacuum and other side LBE) has been reported in literature to be the most critical zone where high temperatures are reached. Numerical Simulations are carried out with Artificial Neural Network coupled Computational Fluid Dynamics (CFD) code, Various studies were carried out after the verification and validation of the initial results. Window being, the main parameter to be optimised, various designs of window were tried, along with change in the window material. The best possible combination has been proposed. The thermal hydraulic studies were carried out to arrive at the acceptable operating conditions for the target. (author)
Prediction of subcooled flow boiling characteristics using two-fluid Eulerian CFD model
Energy Technology Data Exchange (ETDEWEB)
Braz Filho, Francisco A.; Ribeiro, Guilherme B., E-mail: gbribeiro@ieav.cta.br; Caldeira, Alexandre D.
2016-11-15
Highlights: • CFD multiphase model is used to predict subcooled flow boiling characteristics. • Better agreement is achieved for higher saturation pressures. • Onset of nucleate boiling and saturated boiling are well predicted. • CFD multiphase model tends to underestimate the void fraction. • Factors were adjusted in order to improve the void fraction results. - Abstract: The present study concerns a detailed analysis of flow boiling phenomena under high pressure systems using a two-fluid Eulerian approach provided by a Computational Fluid Dynamics (CFD) solver. For this purpose, a vertical heated pipe made of stainless steel with an internal diameter of 15.4 mm was considered as the modeled domain. Two different uniform heat fluxes and three saturation pressures were applied to the channel wall, whereas water mass flux of 900 kg/m{sup 2} s was considered for all simulation cases. The model was validated against a set of experimental data and results have indicated a promising use of the CFD technique for estimation of the wall temperature, the liquid bulk temperature and the location of the departure of nucleate boiling. Changes in factors applied in the modeling of the interfacial heat transfer coefficient and bubble departure frequency were suggested, allowing a better prediction of the void fraction along the heated channel. The commercial CFD solver FLUENT 14.5 was used for the model implementation.
Prediction of subcooled flow boiling characteristics using two-fluid Eulerian CFD model
International Nuclear Information System (INIS)
Braz Filho, Francisco A.; Ribeiro, Guilherme B.; Caldeira, Alexandre D.
2016-01-01
Highlights: • CFD multiphase model is used to predict subcooled flow boiling characteristics. • Better agreement is achieved for higher saturation pressures. • Onset of nucleate boiling and saturated boiling are well predicted. • CFD multiphase model tends to underestimate the void fraction. • Factors were adjusted in order to improve the void fraction results. - Abstract: The present study concerns a detailed analysis of flow boiling phenomena under high pressure systems using a two-fluid Eulerian approach provided by a Computational Fluid Dynamics (CFD) solver. For this purpose, a vertical heated pipe made of stainless steel with an internal diameter of 15.4 mm was considered as the modeled domain. Two different uniform heat fluxes and three saturation pressures were applied to the channel wall, whereas water mass flux of 900 kg/m"2 s was considered for all simulation cases. The model was validated against a set of experimental data and results have indicated a promising use of the CFD technique for estimation of the wall temperature, the liquid bulk temperature and the location of the departure of nucleate boiling. Changes in factors applied in the modeling of the interfacial heat transfer coefficient and bubble departure frequency were suggested, allowing a better prediction of the void fraction along the heated channel. The commercial CFD solver FLUENT 14.5 was used for the model implementation.
Drag Reduction CFD Simulations and Flow Visualization of Light Vehicle-Trailer Systems
Sigurdson, Lorenz; Boyer, Henry; Lange, Carlos F.
2016-11-01
Experiments and CFD were performed to study the effect a deflector had on the flow and drag force associated with a 2010 F-150 truck and cargo trailer Light Vehicle-Trailer System (LVTS). Image Correlation Velocimetry (ICV) on smokewire streaklines measured the velocity field on the model mid-plane. CFD estimated the drag reduction as 13% at a Re of 14,900 with a moving ground-plane, and 17% without. Experiments suggested that the low Re does not diminish the full-scale relevance of the drag reduction results. One low Re effect was the presence of a separation bubble on the hood of the tow vehicle whose size reduced with an increase in Re. Three other characteristic flow patterns were identified: separation off the lead vehicle cab, stagnation of the free-stream on the trailer face for the no-deflector case, and subsequent separation at the trailer front corner. Comparisons of the ICV and CFD results with no deflector indicated good agreement in the direction of the velocity vectors, and the smoke streaklines and CFD streamlines also agreed well. However, for the deflector case, the CFD found an entirely different topological solution absent in the experiment. A pair of vertically-oriented mid-plane vortices were wrapped around the front of the trailer. Support from the Canadian Natural Sciences and Engineering Research Council Grant 41747 is gratefully acknowledged.
Carga inmediata con implantes en maxilar superior Immediate loading of implants in the maxilla
Directory of Open Access Journals (Sweden)
F. Monje Gil
2007-08-01
Full Text Available La carga inmediata en la mandíbula se ha incorporado a la práctica clínica en primer lugar y, por las características del hueso, se realiza de forma protocolizada. Sin embargo, en el maxilar superior no hay evidencia científica para realizarlo de forma cotidiana. Las razones son debidas a que el maxilar superior, en general, alberga una masa ósea de menor densidad. Por otro lado, en el maxilar superior pueden coexistir diferentes densidades óseas (según la clasificación de Misch en el mismo individuo. Además, por las características anatómicas del maxilar superior (reabsorción labiopalatina el alineamiento axial es asumible pero, sin embargo, el paralelismo de los implantes es difícil.16,17 El objetivo del presente trabajo es analizar la información científica de la que disponemos para confirmar si es posible la carga inmediata sobre el maxilar superior. Para ello estudiaremos varios aspectos de la carga inmediata en el maxilar superior: • Sobredentaduras • Prótesis fija completa • Prótesis parcial fija • Prótesis unitaria fija • Requerimientos protésicos • ContraindicacionesImmediate loading in the mandible has been introduced into clinical practice taking first place and, and because of the characteristics of the bone, this is carried out following a protocol. However, in the maxilla there is no scientific evidence for routinely carrying this out. This is because the maxilla, in general, has a lower bone mass density. Moreover, in the maxilla various densities may coexist (according to Misch’s classification in the same individual. In addition, given the anatomic characteristics of the maxilla (lip and palate resorption, axial alignment can be carried out, but implant parallelism is difficult.16,17 The aim of this paper is to analyze the scientific information that we have at our disposal in order to confirm whether immediate loading in the maxilla is possible. For this we will study various aspects of
Assessment of CFD Hypersonic Turbulent Heating Rates for Space Shuttle Orbiter
Wood, William A.; Oliver, A. Brandon
2011-01-01
Turbulent CFD codes are assessed for the prediction of convective heat transfer rates at turbulent, hypersonic conditions. Algebraic turbulence models are used within the DPLR and LAURA CFD codes. The benchmark heat transfer rates are derived from thermocouple measurements of the Space Shuttle orbiter Discovery windward tiles during the STS-119 and STS-128 entries. The thermocouples were located underneath the reaction-cured glass coating on the thermal protection tiles. Boundary layer transition flight experiments conducted during both of those entries promoted turbulent flow at unusually high Mach numbers, with the present analysis considering Mach 10{15. Similar prior comparisons of CFD predictions directly to the flight temperature measurements were unsatisfactory, showing diverging trends between prediction and measurement for Mach numbers greater than 11. In the prior work, surface temperatures and convective heat transfer rates had been assumed to be in radiative equilibrium. The present work employs a one-dimensional time-accurate conduction analysis to relate measured temperatures to surface heat transfer rates, removing heat soak lag from the flight data, in order to better assess the predictive accuracy of the numerical models. The turbulent CFD shows good agreement for turbulent fuselage flow up to Mach 13. But on the wing in the wake of the boundary layer trip, the inclusion of tile conduction effects does not explain the prior observed discrepancy in trends between simulation and experiment; the flight heat transfer measurements are roughly constant over Mach 11-15, versus an increasing trend with Mach number from the CFD.
Status and outlook of CFD technology at Mitsubishi Heavy Industries, Nagoya
Tanioka, Tadayuki
1990-09-01
Computational Fluid Dynamics (CFD) technology has made tremendous progress in the last several years. It has matured to become a practical simulation tool in aircraft industries. In MHI, CFD has become an indispensible tool for aerodynamic design aerospace vehicles. The present status is described of this advanced technology at MHI. Also mentioned are some future advances of the fast growing technology as well as associated hardware requirements.
Los exilios de católicos y arrianos bajo Leovigildo y Recaredo
Directory of Open Access Journals (Sweden)
Vallejo Girvés, Margarita
2003-06-01
Full Text Available In this paper we try to analyse the various topics of the exile that have been applied by the visigothic kings Leovigild and Reccared. It is known that most part of the individuals that had suffered this exile were ecclesiasticals, catholics under Leovigild and arians during Reccared, but all of them were of germanic origin.
En este artículo se analizan los diversos tipos de exilio que aplicaron los monarcas visigodos Leovigildo y Recaredo. Se da la circunstancia de que la mayoría de ellos fueron eclesiásticos y que bajo Leovigildo lo sufrieron singularmente los católicos y los arríanos bajo Recaredo, pero en ambos casos todos los condenados son de origen germánico.
Location and sizing of a plant stack: Design study using CFD
International Nuclear Information System (INIS)
Petrangeli, Gianni
2011-01-01
Highlights: → The paper is a test of applicability of CFD Codes to a nuclear plant stack. → Six cases are studied and comparison is made with common methods. → A comparison with field test data is made. → The study shows that CFD Codes are adequate even in presence of complicated building arrangements. - Abstract: The effect of the presence of a stack on the ground level concentration of emissions near the plant is to significantly decrease the concentrations (in practical cases of interest, by a factor of 5-10), while the presence of nearby plant buildings is to partly eliminate this beneficial effect due to the effect of the building wake. The author of this paper believes that the practical methods currently used for the evaluation of ground concentrations in these cases deserve some improvement. One line of development here suggested is the use of Computer Fluid Dynamics (CFD) codes. The author believes that presently available Code Packages in this field are sufficiently accurate. A number of case studies are presented in this paper, with the aim of encouraging the use of these rather simple methods of study. Moreover, a comparison of calculation results with a field test results confirms also the quantitative reliability of the calculation method here proposed. The main conclusions of this exercise could be the following: -The use of CFD Computer Codes seems suitable for atmospheric dispersion calculations of interest to the nuclear plant designer and safety analyst; in particular, for design studies aimed at the definition of nuclear plant and stack arrangements, the result of this exercise seem to indicate that the methods here used are completely suitable for the comparison of various solutions. -The use of CFD codes may avoid wrong decisions, like the elimination of a stack in the design of a nuclear plant; excessive and detrimental over-conservatism can also be avoided. -When adequate guidance is provided, as this paper attempts to do (), the CFD
Moisture content evaluation of biomass using CFD approach
Directory of Open Access Journals (Sweden)
Thomas Bartzanas
2012-10-01
Full Text Available In grass conservation systems, drying in the field is an essential process upon which the quality and quantity of the material to be conserved is dependent on. In this study a Computational Fluid Dynamics (CFD model, previously validated, was used to assess qualitatively and quantitatively the field drying process of cut grass under different weather conditions and structural specifications of the grass. The use of the CFD model depicts the climate heterogeneity in the grass area with a special focus on moisture distribution, influence of the weather conditions, in order to create the possibility of applying the model as a decision support tool for an enhanced treatment of the grass after cutting.
Vieira, Paula Maria Neto
2016-01-01
A utilização da mochila durante a marcha tem provocado um grande interesse em muitos investigadores, pois o uso de carga nas mochilas e os problemas que isso pode acarretar tem gerado algumas discussões. O objetivo deste estudo foi analisar a marcha ao utilizar carga em mochilas bilaterais de modo a verificar se compensa ou não aos indivíduos andar com este tipo de mochilas. Para isso recorreu-se a métodos de análise como a termografia, cinemática e eletromiografia. Para a realização deste...
CFD simulation and experimental validation of a GM type double inlet pulse tube refrigerator
Banjare, Y. P.; Sahoo, R. K.; Sarangi, S. K.
2010-04-01
Pulse tube refrigerator has the advantages of long life and low vibration over the conventional cryocoolers, such as GM and stirling coolers because of the absence of moving parts in low temperature. This paper performs a three-dimensional computational fluid dynamic (CFD) simulation of a GM type double inlet pulse tube refrigerator (DIPTR) vertically aligned, operating under a variety of thermal boundary conditions. A commercial computational fluid dynamics (CFD) software package, Fluent 6.1 is used to model the oscillating flow inside a pulse tube refrigerator. The simulation represents fully coupled systems operating in steady-periodic mode. The externally imposed boundary conditions are sinusoidal pressure inlet by user defined function at one end of the tube and constant temperature or heat flux boundaries at the external walls of the cold-end heat exchangers. The experimental method to evaluate the optimum parameters of DIPTR is difficult. On the other hand, developing a computer code for CFD analysis is equally complex. The objectives of the present investigations are to ascertain the suitability of CFD based commercial package, Fluent for study of energy and fluid flow in DIPTR and to validate the CFD simulation results with available experimental data. The general results, such as the cool down behaviours of the system, phase relation between mass flow rate and pressure at cold end, the temperature profile along the wall of the cooler and refrigeration load are presented for different boundary conditions of the system. The results confirm that CFD based Fluent simulations are capable of elucidating complex periodic processes in DIPTR. The results also show that there is an excellent agreement between CFD simulation results and experimental results.
CFD evaluation of hydrogen risk mitigation measures in a VVER-440/213 containment
Energy Technology Data Exchange (ETDEWEB)
Heitsch, Matthias, E-mail: Matthias.Heitsch@ec.europa.e [Institute for Energy, Joint Research Centre, PO Box 2, 1755 ZG Petten (Netherlands); Huhtanen, Risto [VTT Technical Research Centre of Finland, PO Box 1000, FI-02044 VTT (Finland); Techy, Zsolt [VEIKI Institute for Electric Power Research Co., PO Box 80, H-1251 Budapest (Hungary); Fry, Chris [Serco, Winfrith Technology Centre, Dorchester, Dorset DT2 8DH (United Kingdom); Kostka, Pal [VEIKI Institute for Electric Power Research Co., PO Box 80, H-1251 Budapest (Hungary); Niemi, Jarto [VTT Technical Research Centre of Finland, PO Box 1000, FI-02044 VTT (Finland); Schramm, Berthold [Gesellschaft fuer Anlagen- und Reaktorsicherheit, GRS mbH, Schwertnergasse 1, 50667 Koeln (Germany)
2010-02-15
In the PHARE project 'Hydrogen Management for the VVER440/213' (HU2002/000-632-04-01), CFD (Computational Fluid Dynamics) calculations using GASFLOW, FLUENT and CFX were performed for the Paks NPP (Nuclear Power Plant), modelling a defined severe accident scenario which involves the release of hydrogen. The purpose of this work is to demonstrate that CFD codes can be used to model gas movement inside a containment during a severe accident. With growing experience in performing such analyses, the results encourage the use of CFD in assessing the risk of losing containment integrity as a result of hydrogen deflagrations. As an effective mitigation measure in such a situation, the implementation of catalytic recombiners is planned in the Paks NPP. In order to support these plans both unmitigated and recombiner-mitigated simulations were performed. These are described and selected results are compared. The codes CFX and FLUENT needed refinement to their models of wall and bulk steam condensation in order to be able to fully simulate the severe accident under consideration. Several CFD codes were used in parallel to model the same accident scenario in order to reduce uncertainties in the results. Previously it was considered impractical to use CFD codes to simulate a full containment subject to a severe accident extending over many hours. This was because of the expected prohibitive computing times and missing physical capabilities of the codes. This work demonstrates that, because of developments in the capabilities of CFD codes and improvements in computer power, these calculations have now become feasible.
CFD simulations of steady flows over the IAR 65o delta wing
International Nuclear Information System (INIS)
Benmeddour, A.; Mebarki, Y.; Huang, X.Z.
2004-01-01
Computational Fluid Dynamics (CFD) studies have been conducted to simulate vortical flows around the IAR 65 o delta wing with a sharp leading edge. The effects of the centerbody on the aerodynamic characteristics of the wing are also investigated. Two flow solvers have been employed to compute steady inviscid flows over with and without centerbody configurations of the wing. These two solvers are an IAR in-house code, FJ3SOLV, and the CFD-FASTRAN commercial software. The computed flow solutions of the two solvers have been compared and correlated against the IAR wind tunnel data, including Pressure Sensitive Paint (PSP) measurements. The major features of the primary vortex have been well captured and overall reasonable accuracy was obtained. In accordance with the experimental observations for the flow conditions considered, the CFD computations revealed no major global effects of the centerbody on the surface pressure distributions of the wing and on the lift coefficient. However, CFD-FASTRAN seems to predict a vortex breakdown, which is neither predicted by FJ3SOLV nor observed in the wind tunnel for the flow conditions considered. (author)
Influence of Contact Angle Boundary Condition on CFD Simulation of T-Junction
Arias, S.; Montlaur, A.
2018-03-01
In this work, we study the influence of the contact angle boundary condition on 3D CFD simulations of the bubble generation process occurring in a capillary T-junction. Numerical simulations have been performed with the commercial Computational Fluid Dynamics solver ANSYS Fluent v15.0.7. Experimental results serve as a reference to validate numerical results for four independent parameters: the bubble generation frequency, volume, velocity and length. CFD simulations accurately reproduce experimental results both from qualitative and quantitative points of view. Numerical results are very sensitive to the gas-liquid-wall contact angle boundary conditions, confirming that this is a fundamental parameter to obtain accurate CFD results for simulations of this kind of problems.
Extension of CFD Codes Application to Two-Phase Flow Safety Problems - Phase 3
International Nuclear Information System (INIS)
Bestion, D.; Anglart, H.; Mahaffy, J.; Lucas, D.; Song, C.H.; Scheuerer, M.; Zigh, G.; Andreani, M.; Kasahara, F.; Heitsch, M.; Komen, E.; Moretti, F.; Morii, T.; Muehlbauer, P.; Smith, B.L.; Watanabe, T.
2014-11-01
The Writing Group 3 on the extension of CFD to two-phase flow safety problems was formed following recommendations made at the 'Exploratory Meeting of Experts to Define an Action Plan on the Application of Computational Fluid Dynamics (CFD) Codes to Nuclear Reactor Safety Problems' held in Aix-en-Provence, in May 2002. Extension of CFD codes to two-phase flow is significant potentiality for the improvement of safety investigations, by giving some access to smaller scale flow processes which were not explicitly described by present tools. Using such tools as part of a safety demonstration may bring a better understanding of physical situations, more confidence in the results, and an estimation of safety margins. The increasing computer performance allows a more extensive use of 3D modelling of two-phase Thermal hydraulics with finer nodalization. However, models are not as mature as in single phase flow and a lot of work has still to be done on the physical modelling and numerical schemes in such two-phase CFD tools. The Writing Group listed and classified the NRS problems where extension of CFD to two-phase flow may bring real benefit, and classified different modelling approaches in a first report (Bestion et al., 2006). First ideas were reported about the specification and analysis of needs in terms of validation and verification. It was then suggested to focus further activity on a limited number of NRS issues with a high priority and a reasonable chance to be successful in a reasonable period of time. The WG3-step 2 was decided with the following objectives: - selection of a limited number of NRS issues having a high priority and for which two-phase CFD has a reasonable chance to be successful in a reasonable period of time; - identification of the remaining gaps in the existing approaches using two-phase CFD for each selected NRS issue; - review of the existing data base for validation of two-phase CFD application to the selected NRS problems
Determinación en túnel aerodinámico de las cargas de viento sobre tres marquesinas
Directory of Open Access Journals (Sweden)
Blanco, Pedro Juan
1981-12-01
Full Text Available Not available.
Las marquesinas de las graderías de los estadios son estructuras sometidas básicamente a tres tipos de cargas: las debidas a su propio peso, las debidas a la nieve y las debidas a la acción del viento. La determinación de las dos primeras es relativamente sencilla y no expuesta a error; sin embargo, la determinación de las cargas producidas por la acción del viento es prácticamente inabordable por métodos teóricos y muy propensa a error si se hace por métodos simplificados, por lo que resulta casi imprescindible recurrir a su determinación práctica mediante ensayos en modelos a escala en túnel aerodinámico.
Este trabajo presenta los resultados obtenidos en cuatro ensayos en modelo de tres marquesinas distintas, comparándolos con la estimación que se hubiera realizado si se hubiera atendido a los métodos simplificados de las normas en vigor.
Olivella Rosell, Pol
2012-01-01
El presente proyecto se ha desarrollado para proponer una metodología de modelización de la demanda de carga lenta y rápida de vehículos eléctricos para el estudio de impacto en la red de distribución. El capítulo 1 es la memoria del análisis del estado del arte de esta temática. En el capítulo 2 se desarrolla el modelo para carga lenta, en el capítulo 3 se añade la carga rápida y en el capítulo 4 se aplica a un caso de estudio. En los últimos años el desarrollo de los vehículos eléctri...
PENGARUH VARIASI BENTUK BURITAN KAPAL TERHADAP HAMBATAN TOTAL MENGGUNAKAN METODE CFD
Deddy Chrismianto; Berlian Arswendo Adietya
2014-01-01
Penelitian ini dilakukan dengan cara menganalisa dan menghitung hambatan total kapal menggunakan model 3D pada berbagai variasi bentuk buritan menggunakan CFD (Computational Fluid Dynamic).Berdasarkan hasil analisa dan perhitungan didapatkan hambatan total yang terkecil menggunakan CFD untuk berbagai variasi bentuk buritan kapal, dengan studi kasus pada type KCS (Kriso Container Ship). Hambatan total terkecil pada kondisi kecepatan fn 0.22 adalah 646.57 KN yaitu pada model 1, kemudian hambata...
Pengaruh Variasi Bentuk Buritan Kapal Terhadap Hambatan Total Menggunakan Metode Cfd
Chrismianto, Deddy; Adietya, Berlian Arswendo
2014-01-01
Penelitian ini dilakukan dengan cara menganalisa dan menghitung hambatan total kapal menggunakan model 3D pada berbagai variasi bentuk buritan menggunakan CFD (Computational Fluid Dynamic).Berdasarkan hasil analisa dan perhitungan didapatkan hambatan total yang terkecil menggunakan CFD untuk berbagai variasi bentuk buritan kapal, dengan studi kasus pada type KCS (Kriso Container Ship). Hambatan total terkecil pada kondisi kecepatan fn 0.22 adalah 646.57 KN yaitu pada model 1, kemudian hambata...
CFD Investigation on Long-Haul Passenger Bus
Tan, C. F.; Tee, B. T.; Law, H. C.; Lim, T. L.
2015-09-01
Air flow distribution is one of the important factors that will influence the bus passenger comfort during long haul travel. Poor air flow distribution not only cause discomfort to the bus passenger but also influence their travel mode as well. The main purpose of this study is to investigate the air flow performance of the bus air-conditioning system through CFD simulation approach. A 3D CAD model of air ducts was drawn and hence analysed by using CFD software, namely ANSYS Fluent, to determine the airflow rate for every outlets of the air-conditioning system. The simulated result was then validated with experimental data obtained from prototype model of air duct. Based on the findings, new design concepts is proposed with the aim to meet the industry requirement as well as to improve the bus passenger comfort during long haul travel.
Estudio de una Cronosecuencia de Suelos en el Bajo Cauca (Antioquia
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Jaramillo J. Daniel F.
1996-09-01
Full Text Available En la región del Bajo Cauca, Antioquia, se estudiaron tres terrazas, a diferentes alturas, las cuales poseen diferencias apreciables entre la evolución de sus respectivos suelos. La terraza de mayor altura presentó los suelos más evolucionados: Typic Paleudult; la de mediana altura presentó suelos de incipiente evolución, clasificados como Typic Dystropept y la de menor altitud presentó suelos recientes, con muy bajo grado de evolución: Tropic Fluvaquent. Las diferencias en evolución observadas entre los suelos se deben a los largos intervalos de tiempo transcurridos entre la formación de los tres niveles de las terrazas. La fertilidad natural de los suelos desarrollados sobre las terrazas alta y media se puede calificar como baja a muy baja; por su parte, la terraza a menor altura posee alta fertilidad.
Energy Technology Data Exchange (ETDEWEB)
Schramm, Berthold; Stewering, Joern; Sonnenkalb, Martin
2014-03-15
CFD (Computational Fluid Dynamic) simulation techniques have a growing relevance for the simulation and assessment of accidents in nuclear reactor containments. Some fluid dynamic problems like the calculation of the flow resistances in a complex geometry, turbulence calculations or the calculation of deflagrations could only be solved exactly for very simple cases. These fluid dynamic problems could not be represented by lumped parameter models and must be approximated numerically. Therefore CFD techniques are discussed by a growing international community in conferences like the CFD4NRS-conference. Also the number of articles with a CFD topic is increasing in professional journals like Nuclear Engineering and Design. CFD tools like GASFLOW or GOTHIC are already in use in European nuclear site licensing processes for future nuclear power plants like EPR or AP1000 and the results of these CFD tools are accepted by the authorities. For these reasons it seems to be necessary to build up national competences in the field of CFD techniques and it is important to validate and assess the existing CFD tools. GRS continues the work for the validation and assessment of CFD codes for the simulation of accident scenarios in a nuclear reactor containment within the framework of the BMWi sponsored project RS1500. The focus of this report is on the following topics: - Further validation of condensation models from GRS, FZJ and ANSYS and development of a new condensate model. - Validation of a new turbulence model which was developed by the University of Stuttgart in cooperation with ANSYS. - The formation and dissolution of light gas stratifications are analyzed by large scale experiments. These experiments were simulated by GRS. - The AREVA correlations for hydrogen recombiners (PARs) could be improved by GRS after the analysis of experimental data. Relevant experiments were simulated with this improved recombiner correlation. - Analyses on the simulation of H{sub 2
Serie Madera para construcción La madera certificada bajo el concepto del triple resultado
Camacho-Cornejo, Diego; Moya-Roque, Róger
2012-01-01
A nivel mundial existe una tendencia de utilización de los productos certificados de madera bajo el concepto de triple resultado. En Costa Rica, diferentes empresas trabajan bajo este concepto. Es por ello que el presente trabajo tiene como objetivo mostrar el desarrollo de la madera certificada en Costa Rica, estableciendo la importancia de utilizar este tipo de madera, las ventajas de utilizarla en relación a aquella que no presenta esta certificación. Así mismo se presenta un detalle de la...
Experimental PIV and CFD studies of UV-peroxide advanced oxidation reactors for water treatment
International Nuclear Information System (INIS)
Sozzi, A.; Taghipour, F.
2004-01-01
An experimental and numerical study of the flow characteristics in an annular UV reactor, as used for drinking water disinfection or Advanced Oxidation Processes, was carried out using Particle Image Velocimetry (PIV) and Computational Fluid Dynamics (CFD). The influence of different turbulence models and mesh structures on the CFD results was investigated. By qualitative and quantitative comparison of CFD and PIV experimental data, it was shown that the Realizable k-e- turbulence model is best suited for simulating the hydrodynamics of this geometry. (author)
An overview of past and present CFD activities within the framework of WGAMA
International Nuclear Information System (INIS)
Smith, B.L.; Mahaffy, J.H.; Bestion, D.; Zigh, G.
2011-01-01
In 2003, three Writing Groups (WG1, WG2, WG3) were established within the Working Group on Analysis and Management of Accidents (WGAMA) of the OECD Nuclear Energy Agency. The groups had the responsibility of summarising the state-of-the-art in the application of Computational Fluid Dynamics (CFD) to items of concern in nuclear reactor safety. The Best Practice Guidelines (BPGs) drawn up by the WG1 group defined the procedures which need to be followed to produce trustworthy results from a CFD simulation. The WG2 group itemised the assessment base which underpins single-phase CFD as an established technology. The WG3 group focused on the challenges that still need to be faced before two-phase CFD may be regarded as a mature science. The background to the activity, method of approach, documented evidence, status and current activities are described under appropriate section headings in this paper. (author)
3D CFD Quantification of the Performance of a Multi-Megawatt Wind Turbine
Laursen, J.; Enevoldsen, P.; Hjort, S.
2007-07-01
This paper presents the results of 3D CFD rotor computations of a Siemens SWT-2.3-93 variable speed wind turbine with 45m blades. In the paper CFD is applied to a rotor at stationary wind conditions without wind shear, using the commercial multi-purpose CFD-solvers ANSYS CFX 10.0 and 11.0. When comparing modelled mechanical effects with findings from other models and measurements, good agreement is obtained. Similarly the computed force distributions compare very well, whereas some discrepancies are found when comparing with an in-house BEM model. By applying the reduced axial velocity method the local angle of attack has been derived from the CFD solutions, and from this knowledge and the computed force distributions, local airfoil profile coefficients have been computed and compared to BEM airfoil coefficients. Finally, the transition model of Langtry and Menter is tested on the rotor, and the results are compared with the results from the fully turbulent setup.
3D CFD Quantification of the Performance of a Multi-Megawatt Wind Turbine
International Nuclear Information System (INIS)
Laursen, J; Enevoldsen, P; Hjort, S
2007-01-01
This paper presents the results of 3D CFD rotor computations of a Siemens SWT-2.3-93 variable speed wind turbine with 45m blades. In the paper CFD is applied to a rotor at stationary wind conditions without wind shear, using the commercial multi-purpose CFD-solvers ANSYS CFX 10.0 and 11.0. When comparing modelled mechanical effects with findings from other models and measurements, good agreement is obtained. Similarly the computed force distributions compare very well, whereas some discrepancies are found when comparing with an in-house BEM model. By applying the reduced axial velocity method the local angle of attack has been derived from the CFD solutions, and from this knowledge and the computed force distributions, local airfoil profile coefficients have been computed and compared to BEM airfoil coefficients. Finally, the transition model of Langtry and Menter is tested on the rotor, and the results are compared with the results from the fully turbulent setup
Assessment of CFD capability for prediction of hypersonic shock interactions
Knight, Doyle; Longo, José; Drikakis, Dimitris; Gaitonde, Datta; Lani, Andrea; Nompelis, Ioannis; Reimann, Bodo; Walpot, Louis
2012-01-01
The aerothermodynamic loadings associated with shock wave boundary layer interactions (shock interactions) must be carefully considered in the design of hypersonic air vehicles. The capability of Computational Fluid Dynamics (CFD) software to accurately predict hypersonic shock wave laminar boundary layer interactions is examined. A series of independent computations performed by researchers in the US and Europe are presented for two generic configurations (double cone and cylinder) and compared with experimental data. The results illustrate the current capabilities and limitations of modern CFD methods for these flows.
Energy Technology Data Exchange (ETDEWEB)
Buchholz, Sebastian; Palazzo, Simone; Papukchiev, Angel; Scheurer Martina
2016-12-15
The overall goal of the project RS 1506 ''Development and Validation of Three Dimensional CFD Methods for Reactor Safety Applications'' is the validation of Computational Fluid Dynamics (CFD) software for the simulation of three -dimensional thermo-hydraulic heat and fluid flow phenomena in nuclear reactors. For this purpose a wide spectrum of validation and test cases was selected covering fluid flow and heat transfer phenomena in the downcomer and in the core of pressurized water reactors. In addition, the coupling of the system code ATHLET with the CFD code ANSYS CFX was further developed and validated. The first choice were UPTF experiments where turbulent single- and two-phase flows were investigated in a 1:1 scaled model of a German KONVOI reactor. The scope of the CFD calculations covers thermal mixing and stratification including condensation in single- and two-phase flows. In the complex core region, the flow in a fuel assembly with spacer grid was simulated as defined in the OECD/NEA Benchmark MATIS-H. Good agreement are achieved when the geometrical and physical boundary conditions were reproduced as realistic as possible. This includes, in particular, the consideration of heat transfer to walls. The influence of wall modelling on CFD results was investigated on the TALL-3D T01 experiment. In this case, the dynamic three dimensional fluid flow and heat transfer phenomena were simulated in a Generation IV liquid metal cooled reactor. Concurrently to the validation work, the coupling of the system code ATHLET with the ANSYS CFX software was optimized and expanded for two-phase flows. Different coupling approaches were investigated, in order to overcome the large difference between CPU-time requirements of system and CFD codes. Finally, the coupled simulation system was validated by applying it to the simulation of the PSI double T-junction experiment, the LBE-flow in the MYRRA Spallation experiment and a demonstration test case
CFD analysis of the temperature field in emergency pump room in Loviisa NPP
Energy Technology Data Exchange (ETDEWEB)
Rämä, Tommi, E-mail: tommi.rama@fortum.com [Fortum Power and Heat, P.O.B. 100, FI-00048 Fortum (Finland); Toppila, Timo, E-mail: timo.toppila@fortum.com [Fortum Power and Heat, P.O.B. 100, FI-00048 Fortum (Finland); Kelavirta, Teemu, E-mail: teemu.kelavirta@fortum.com [Fortum Power and Heat, Loviisa Power Plant, P.O.B. 23, FI-07901 Loviisa (Finland); Martin, Pasi, E-mail: pasi.martin@fortum.com [Fortum Power and Heat, Loviisa Power Plant, P.O.B. 23, FI-07901 Loviisa (Finland)
2014-11-15
Highlights: • Laser scanned room geometry from Loviisa NPP was utilized for CFD simulation. • Uncertainty of CFD simulation was estimated using the Grid Convergence Index. • Measured temperature field of pump room was reproduced with CFD simulation. - Abstract: In the Loviisa Nuclear Power Plant (NPP) six emergency pumps belonging to the same redundancy are located in the same room. During a postulated accident the cooling of the room is needed as the engines of the emergency pumps generate heat. Cooling is performed with fans blowing air to the upper part of the room. Temperature limits have been given to the operating conditions of the main components in order to ensure their reliable operation. Therefore the temperature field of the room is important to know. Temperature measurements were made close to the most important components of the pump room to get a better understanding of the temperature field. For these measurements emergency pumps and cooling fan units were activated. To simulate conditions during a postulated accident additional warm-air heaters were used. Computational fluid dynamic (CFD) simulations were made to support plant measurements. For the CFD study one of the pump rooms of Loviisa NPP was scanned with a laser and this data converted to detailed 3-D geometry. Tetrahedral computation grid was created inside the geometry. Grid sensitivity studies were made, and the model was then validated against the power plant tests. With CFD the detailed temperature and flow fields of the whole room were produced. The used CFD model was able to reproduce the temperature field of the measurements. Two postulated accident cases were simulated. In the cases the operating cooling units were varied. The temperature profile of the room changes significantly depending on which units are cooling and which only circulating the air. The room average temperature stays approximately the same. The simulation results were used to ensure the acceptable operating
Factores de riesgo en el bajo peso al nacer
Directory of Open Access Journals (Sweden)
Guillermo Díaz Alonso
1995-06-01
Full Text Available Se realizó un estudio retrospectivo de tipo caso control en el área del Policlínico Docente "Luis A. Turcios Lima" del municipio 10 de Octubre durante el período de 1990 a 1993, con el objetivo de identificar el comportamiento del bajo peso al nacer, establecer la existencia y la intensidad de esta entidad con los factores de riesgo seleccionados, e identificar el grado de influencia individual de dichos factores. La muestra quedó conformada por 92 recién nacidos de bajo peso y 468 con normopeso. Las variables estudiadas fueron la edad materna, la valoración ponderal, las complicaciones obstétricas, las enfermedades asociadas con la gestación, el hábito de fumar y el período intergenésico. Se aplicó el test chi-cuadrado, el odds- -ratio y el de riesgo atribuible en los nacimientos expuestos y en la población total. Todas las variables estuvieron asociadas significativamente con el bajo peso al nacer, y fueron identificadas como factores de riesgo con influencia marcada: la edad materna de 35 años o más, la amenaza de parto prematuro, la rotura prematura de membranas, la toxemia y la diabetes mellitus; con efecto moderado, el bajo peso materno, un período intergenésico menor de 1 año, la hipertensión arterial, el asma bronquial, el hábito de fumar, la sepsis urinaria, y con influencia ligera, la edad materna inferior a los 20 años.A case-control retrospective study was carried out at "Luis A. Turcios Lima" Teaching Polyclinics form 10 de Octubre municipality during the period of 1990-1993, with the aim of identifying the behaviour of low birth weight, establishing the occurrence and intensity of this entity with selected risk factors, and identifying the degree of individual influence of such factors. The sample consisted of 92 low birth weight infants and 468 with normal weight. Variables studied were: maternal age, weight appraisal, and obstetric complications, diseases associated with pregnancy, smoking habit, and the
Directory of Open Access Journals (Sweden)
Eduardo Concepción Batiz
2012-01-01
Full Text Available A atividade do trabalhador que manuseia cargas o predispõe a riscos decorrentes dos fatores biomecânicos, excesso de força, posturas inadequadas e dos fatores organizacionais que, quando utilizados de forma inadequada, sua aplicação repercute na saúde dos trabalhadores e na produção. O presente trabalho foi realizado em 3 comércios atacadistas e tem como objetivo identificar os fatores de risco que podem provocar a prevalência dos sintomas musculoesqueléticos. Aplicaram-se à amostra selecionada de 134 trabalhadores um questionário organizacional, questionário nórdico de sintomas osteomusculares e o guia para avaliação e prevenção dos riscos relativos à manipulação manual de cargas. Ressalta-se que pela carga que carregam, pelas posturas que adotam e pelos sintomas de dor (63,4% da amostra associados aos fatores anteriores, a atividade se constitui em um risco para a saúde. Os resultados corroboram com os estudos, estabelecendo fortes indícios entre a carga física do trabalho e os sintomas musculoesqueléticos.Handling load is an activity that predisposes the worker to risks due to biomechanical factors, excess of force, inadequate positions and organizational factors. These organizational factors may reflect injuries to workers' health and production when used in an inadequate way. This study was carried out using 3 wholesale businesses, aiming to identify the risk factors that could lead to the prevalence of muscle-skeletal symptoms. An organizational questionnaire, a Nordic questionnaire for musculoskeletal symptoms and a guide for assessment and prevention of risks related to handling load was applied to a select sample of 134 workers. It was possible to notice that the loading, the adopted positions and the pain symptoms (63.4% of the sample, associated to the previous factors, may represent a health risk. The results supported the studies, establishing strong indications between physical load of work and muscle
Directory of Open Access Journals (Sweden)
Eduardo Concepción Batiz
2013-03-01
Full Text Available A atividade do trabalhador que manuseia cargas o predispõe a riscos decorrentes dos fatores biomecânicos, excesso de força, posturas inadequadas e dos fatores organizacionais que, quando utilizados de forma inadequada, sua aplicação repercute na saúde dos trabalhadores e na produção. O presente trabalho foi realizado em 3 comércios atacadistas e tem como objetivo identificar os fatores de risco que podem provocar a prevalência dos sintomas musculoesqueléticos. Aplicaram-se à amostra selecionada de 134 trabalhadores um questionário organizacional, questionário nórdico de sintomas osteomusculares e o guia para avaliação e prevenção dos riscos relativos à manipulação manual de cargas. Ressalta-se que pela carga que carregam, pelas posturas que adotam e pelos sintomas de dor (63,4% da amostra associados aos fatores anteriores, a atividade se constitui em um risco para a saúde. Os resultados corroboram com os estudos, estabelecendo fortes indícios entre a carga física do trabalho e os sintomas musculoesqueléticos.Handling load is an activity that predisposes the worker to risks due to biomechanical factors, excess of force, inadequate positions and organizational factors. These organizational factors may reflect injuries to workers' health and production when used in an inadequate way. This study was carried out using 3 wholesale businesses, aiming to identify the risk factors that could lead to the prevalence of muscle-skeletal symptoms. An organizational questionnaire, a Nordic questionnaire for musculoskeletal symptoms and a guide for assessment and prevention of risks related to handling load was applied to a select sample of 134 workers. It was possible to notice that the loading, the adopted positions and the pain symptoms (63.4% of the sample, associated to the previous factors, may represent a health risk. The results supported the studies, establishing strong indications between physical load of work and muscle
Computational Fluid Dynamics (CFD) investigation onto passenger car disk brake design
Munisamy, Kannan M.; Kanasan Moorthy, Shangkari K.
2013-06-01
The aim of this study is to investigate the flow and heat transfer in ventilated disc brakes using Computational Fluid Dynamics (CFD). NACA Series blade is designed for ventilated disc brake and the cooling characteristic is compared to the baseline design. The ventilated disc brakes are simulated using commercial CFD software FLUENTTM using simulation configuration that was obtained from experiment data. The NACA Series blade design shows improvements in Nusselt number compared to baseline design.
Toward a CFD-grade database addressing LWR containment phenomena
International Nuclear Information System (INIS)
Paladino, Domenico; Andreani, Michele; Zboray, Robert; Dreier, Jörg
2012-01-01
Highlights: ► The SETH-2 PANDA tests have supplied data with CFD-grade on plumes and jets at large-scale. ► The PANDA tests have contributed to the understanding of phenomena with high safety relevance for LWRs. ► The analytical activities related increased confidence in the use of various computational tools for safety analysis. - Abstract: The large-scale, multi-compartment PANDA facility (located at PSI in Switzerland) is one of the state-of-the-art facilities which is continuously upgraded to progressively match the requirements of CFD-grade experiments. Within the OECD/SETH projects, the PANDA facility has been used for the creation of an experimental database on basic containment phenomena e.g. gas mixing, transport, stratification, condensation. In the PANDA tests, these phenomena are driven by large scale plumes or jets. In the paper is presented a selection of the SETH PANDA experimental results. Examples of analytical activities performed at PSI using the GOTHIC, CFX-4 and CFX-5 codes will be used to illustrate how the spatial and temporal resolutions of the measurement grid in PANDA tests are adequate for CFD code (and advanced containment codes) assessment and validation purposes.
Xavier, Milton
1982-01-01
Trata de uma metodologia de avaliação de eficiência de empresas de transporte rodoviário de cargas, incluindo estudos de casos com empresas de diferentes portes. O transporte rodoviário de cargas, ao contrário do transporte de passageiros, mereceu, até agora, poucos estudos existindo poucas informações a respeito de seu desempenho. Este assunto somente tornou-se relevante recentemente em função da política de racionalização do uso de combustíveis derivados de petróleo, preconizada pelo ...
Directory of Open Access Journals (Sweden)
María Andrée López
2014-01-01
Full Text Available Fundamentos: La incapacidad laboral permanente (IP supone una importante carga social y económica. El objetivo de este estudio fue estimar la carga de enfermedad debida a la IP en España. Métodos: A partir de la Muestra Continua de Vidas Laborales (MCVL se imputó como diagnóstico de la IP (2009-2012 el de la incapacidad temporal (IT iniciada en 2009 en los individuos que cumplieron dos criterios: larga duración de la IT y corta duración del período entre la IT y la IP. Para los casos con diagnóstico imputado se calculó la carga de enfermedad por IP a partir de los años potenciales de vida laboral perdidos (APVLP, definidos como la diferencia entre la edad de jubilación (65 años y la edad de inicio de la IP. Resultados: Según la MCVL, 163.135 (13,6% personas sufrieron de IT en 2009, de las cuáles a 4.738 (0,39% se le reconoció una IP entre 2009-2012. Se pudo establecer el diagnóstico de IP en 3.073 (64,9% casos. Las causas más frecuentes de IP fueron los trastornos musculo-esqueléticos (27,4% y mentales (11,6% que, asimismo, produjeron mayor cantidad de APVLP por IP: 11.086 (26,5% y 7.052 (16,9%, respectivamente. Los trastornos mentales destacaron por producir IP a edades más jóvenes (mediana=49 años. Conclusiones: Los trastornos mentales y los musculo-esqueléticos representaron la mayor carga de enfermedad en individuos en situación de IP.
International Nuclear Information System (INIS)
Bachar, Abdelaziz; Haslinger, Wolfgang; Scheuerer, Georg; Theodoridis, Georgios
2015-01-01
The objectives of the project were: Improvement of the simulation accuracy for nuclear reactor thermo-hydraulics by coupling system codes with three-dimensional CFD software; Extension of CFD software to predict thermo-hydraulics in advanced reactor concepts; Validation of the CFD software by simulation different UPTF TRAM-C test cases and development of best practice guidelines. The CFD module was based on the ANSYS CFD software and the system code ATHLET of GRS. All three objectives were met: The coupled ATHLET-ANSYS CFD software is in use at GRS and TU Muenchen. Besides the test cases described in the report, it has been used for other applications, for instance the TALL-3D experiment of KTH Stockholm. The CFD software was extended with material properties for liquid metals, and validated using existing data. Several new concepts were tested when applying the CFD software to the UPTF test cases: Simulations with Conjugate Heat Transfer (CHT) were performed for the first time. This led to better agreement between predictions and data and reduced uncertainties when applying temperature boundary conditions. The meshes for the CHT simulation were also used for a coupled fluid-structure-thermal analysis which was another novelty. The results of the multi-physics analysis showed plausible results for the mechanical and thermal stresses. The workflow developed as part of the current project can be directly used for industrial nuclear reactor simulations. Finally, simulations for two-phase flows with and without interfacial mass transfer were performed. These showed good agreement with data. However, a persisting problem for the simulation of multi-phase flows are the long simulation times which make use for industrial applications difficult.
CFD simulation on critical heat flux of flow boiling in IVR-ERVC of a nuclear reactor
Energy Technology Data Exchange (ETDEWEB)
Zhang, Xiang, E-mail: zhangxiang3@snptc.com.cn [State Nuclear Power Technology Research & Development Center, South Area, Future Science and Technology Park, Chang Ping District, Beijing 102209 (China); Hu, Teng [State Nuclear Power Technology Research & Development Center, South Area, Future Science and Technology Park, Chang Ping District, Beijing 102209 (China); Chen, Deqi, E-mail: chendeqi@cqu.edu.cn [Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Chongqing University, 400044 (China); Zhong, Yunke; Gao, Hong [Key Laboratory of Low-grade Energy Utilization Technologies and Systems, Chongqing University, 400044 (China)
2016-08-01
Highlights: • CFD simulation on CHF of boiling two-phase flow in ERVC is proposed. • CFD simulation result of CHF agrees well with that of experimental result. • The characteristics of boiling two-phase flow and boiling crisis are analyzed. - Abstract: The effectiveness of in-vessel retention (IVR) by external reactor vessel cooling (ERVC) strongly depends on the critical heat flux (CHF). As long as the local CHF does not exceed the local heat flux, the lower head of the pressure vessel can be cooled sufficiently to prevent from failure. In this paper, a CFD simulation is carried out to investigate the CHF of ERVC. This simulation is performed by a CFD code fluent couple with a boiling model by UDF (User-Defined Function). The experimental CHF of ERVC obtained by State Nuclear Power Technology Research and Development Center (SNPTRD) is used to validate this CFD simulation, and it is found that the simulation result agrees well with the experimental result. Based on the CFD simulation, detailed analysis focusing on the pressure distribution, velocity distribution, void fraction distribution, heating wall temperature distribution are proposed in this paper.
International Nuclear Information System (INIS)
Kim, Seong Gu; Lee, Youho; Ahn, Yoonhan; Lee, Jeong Ik
2016-01-01
Highlights: • CFD analyses were performed to find performance of PCHE for supercritical CO 2 power cycle. • CFD results were obtained beyond the limits of existing correlations. • Designs of different PCHEs with different correlations were compared. • A new CFD-aided correlation covering a wider Reynolds number range was proposed. - Abstract: While most conventional PCHE designs for working fluid of supercritical CO 2 require an extension of valid Reynolds number limits of experimentally obtained correlations, Computational Fluid Dynamics (CFD) code ANSYS CFX was used to explore validity of existing correlations beyond their tested Reynolds number ranges. For heat transfer coefficient correlations, an appropriate piece-wising with Ishizuka’s and Hesselgreaves’s correlation is found to enable an extension of Reynolds numbers. For friction factors, no single existing correlation is found to capture different temperature and angular dependencies for a wide Reynolds number range. Based on the comparison of CFD results with the experimentally obtained correlations, a new CFD-aided correlation covering an extended range of Reynolds number 2000–58,000 for Nusselt number and friction factor is proposed to facilitate PCHE designs for the supercritical CO 2 Brayton cycle application.
Situación General de la Industria de la Construcción de Bajo Bordo
Chui, Alexander; Gamero, Magali; Cornejo, Karla; Rios, Vanessa; Valdivia, Maria Laura; Benzaquén de las Casas, Jorge
2016-01-01
Objetivo: Determinar las condiciones en que se encuentra la industria de construcción naval de bajo bordo en el Perú, relacionado con su contexto latinoamericano. Métodos: Se estableció un protocolo de actuación a base entrevistas, cuestionarios y recopilación de datos con el fin de conocer los principales indicadores de la dinámica funcional e industria de construcción naval de bajo bordo. Resultados: El Perú ha crecido notablemente en las últimas dos décadas como consecuencia de la apertura...
Mixing and RTD in tanks: radiotracer experiments and CFD simulations
International Nuclear Information System (INIS)
Thatte, A.R.; Patwardhan, A.P.; Pant, H.J.; Sharma, V.K.; Gursharan Singh; Berne, Ph.
2004-01-01
The present work is directed towards exploring the possibility of developing a model for predicting the residence time distribution based on the actual flow and turbulence fields present within the reactor. In view of this, experiments have been carried out to characterize mixing processes in two different equipment: jet mixer and stirred tank reactor. CFD models have been developed to predict the mixing time and residence time distribution in these equipments. In all the case, it is observed that the CFD predictions agree well with the experimental measurements. (author)
Mass conservative fluid flow visualization for CFD velocity fields
International Nuclear Information System (INIS)
Li, Zhenquan; Mallinson, Gordon D.
2001-01-01
Mass conservation is a key issue for accurate streamline and stream surface visualization of flow fields. This paper complements an existing method (Feng et al., 1997) for CFD velocity fields defined at discrete locations in space that uses dual stream functions to generate streamlines and stream surfaces. Conditions for using the method have been examined and its limitations defined. A complete set of dual stream functions for all possible cases of the linear fields on which the method relies are presented. The results in this paper are important for developing new methods for mass conservative streamline visualization from CFD data and using the existing method
Sousa, Vívian Aparecida Lima
2012-01-01
A presente dissertação estudou o compartamento térmico, físico e mecânico das argamassas de revestimentos compostas por gesso puro, gesso/EVA (ethylene-vinyl acetate copolymer) e gesso/vermiculita aplicadas nas superficies das paredes de edificação visando à redução da carga térmica relativamente às paredes convencionais constituídas de tijolos de cerâmica e argamassas de cimento-areia, tomadas como referência. O objetivo foi obter um material capaz de reduzir a carga térmica e, por conseguin...
Pereira,José Moreira; Silva,Cirley Santos da; Porto,Luís Fernando Bruzzi; Póvoa,Luiz Gallotti; Moreira,Aline Santos; Alves,Jorge Roberto
2002-01-01
O teste de carga viral foi concebido para acompanhar a evolução e o tratamento do paciente com diagnóstico confirmado de HIV-1. Contudo, sua especificidade diagnóstica não foi ainda avaliada em pessoas que apresentam um teste sorológico negativo. Mesmo assim, ele tem sido erroneamente utilizado para o diagnóstico da infecção primária pelo HIV-1. Este trabalho relata quatro pacientes em que a carga viral plasmática NucliSens (Organon Teknika) foi repetidamente positiva na ausência de anticorpo...
DEFF Research Database (Denmark)
Rong, Li; Nielsen, Peter Vilhelm; Bjerg, Bjarne Schmidt
2016-01-01
scale pig barns was simulated to show the procedures of validating a CFD simulation in livestock buildings. After summarizing the guideline and/or best practice for CFD modeling, the authors addressed the issues related to numerical methods and the governing equations, which were limited to RANS models....... Although it is not necessary to maintain the same format of reporting the CFD modeling as presented in this paper, the authors would suggest including all the information related to the selection of turbulence models, difference schemes, convergence criteria, boundary conditions, geometry simplification......, simulating domain etc. This information is particularly important for the readers to evaluate the quality of the CFD simulation results....
Simulation of steady-state natural convection using CFD
Energy Technology Data Exchange (ETDEWEB)
Zitzmann, T.; Pfrommer, P. [Univ. of Applied Sciences, Coberg (Germany); Cook, M.; Rees, S.; Marjanovic, L. [De Montfort Univ., Leicester (United Kingdom). Inst. of Energy and Sustainable Development
2005-07-01
Building materials play an important role in the creation of comfortable indoor environments and can reduce dependence on high energy use mechanical systems. Correct predictions between building structure and heat transfer are needed in order to achieve optimal conditions. Heat transfer is dependent on the velocity and temperature distribution in a room, particularly in the wall boundary layer. This paper discussed the modeling of air flow and heat transfer over a heated vertical plate in a differentially-heated cavity using Computational Fluid Dynamics (CFD). Guidelines on the use of CFD with unstructured meshes to model buoyancy-driven flow in a cavity were presented. Benchmark CFD results were compared with published analytical data. The finite volume method was employed using an unstructured mesh containing tetrahedral and prism elements, so that local numerical diffusion was reduced and therefore suitable for complex flows. The code was based on a couple solver for solving the differential equations using the fully implicit discretization method. Hydrodynamic equations were treated as one single system. A false time stepping method was used to reduce the number of iterations required for convergence, which also guided the solutions to a steady-state solution. It was concluded that the methodology achieves accurate predictions, and is suitable for the modeling of heat transfer optimizations. 13 refs., 7 figs.
CFD Simulations of a Single-phase Mixing Experiment
International Nuclear Information System (INIS)
Bertolotto, Davide; Chawla, Rakesh; Manera, Annalisa; Prasser, Horst-Michael
2008-01-01
The current paper reports on an investigation of the capabilities of CFD codes to model multidimensional mixing phenomena in a loop. For the purpose, a test facility consisting of two loops connected by a double T-junction has been built at the Paul Scherrer Institut (PSI). Experiments were carried out, in which a tracer was injected in one loop and the tracer distribution before and after the T-junction was measured by means of wire-mesh sensors located at the outlets of the junction. The tracer distribution after the T-junction is strongly dependent on 3D mixing phenomena, which are dominant due to the particular geometry of the set-up. For the CFD analysis, a 3D model of the double T-junction was created, and different simulations were performed with ANSYS-CFX to study the sensitivity of the results with respect to parameters such as mesh refinement, integration time step, turbulence model, profiles for inlet velocity and injected tracer concentration. Thereafter, these results were compared with the experimental data. The comparisons have clearly pointed out that 3D modelling is able to reproduce (at least qualitatively) the experimental results. Moreover, it has been found that the CFD results are strongly influenced by the velocity profile assumptions at the inlets of the double T-junction. (authors)
A CFD model for pollutant dispersion in rivers
Directory of Open Access Journals (Sweden)
Modenesi K.
2004-01-01
Full Text Available Studies have shown that humankind will experience a water shortage in the coming decades. It is therefore paramount to develop new techniques and models with a view to minimizing the impact of pollution. It is important to predict the environmental impact of new emissions in rivers, especially during periods of drought. Computational fluid dynamics (CFD has proved to be an invaluable tool to develop models able to analyze in detail particle dispersion in rivers. However, since these models generate grids with thousands (even millions of points to evaluate velocities and concentrations, they still require powerful machines. In this context, this work contributes by presenting a new three-dimensional model based on CFD techniques specifically developed to be fast, providing a significant improvement in performance. It is able to generate predictions in a couple of hours for a one-thousand-meter long section of river using Pentium IV computers. Commercial CFD packages would require weeks to solve the same problem. Another innovation inb this work is that a half channel with a constant elliptical cross section represents the river, so the Navier Stokes equations were derived for the elliptical system. Experimental data were obtained from REPLAN (PETROBRAS refining unit on the Atibaia River in São Paulo, Brazil. The results show good agreement with experimental data.
Computational Fluid Dynamics (CFD) investigation onto passenger car disk brake design
International Nuclear Information System (INIS)
Munisamy, Kannan M; Moorthy, Shangkari K Kanasan
2013-01-01
The aim of this study is to investigate the flow and heat transfer in ventilated disc brakes using Computational Fluid Dynamics (CFD). NACA Series blade is designed for ventilated disc brake and the cooling characteristic is compared to the baseline design. The ventilated disc brakes are simulated using commercial CFD software FLUENT TM using simulation configuration that was obtained from experiment data. The NACA Series blade design shows improvements in Nusselt number compared to baseline design.
An overview of CFD and PIV application in investigation of solar thermal systems
DEFF Research Database (Denmark)
Ai, Ning; Fan, Jianhua; Ji, Jianbing
2007-01-01
. The most promising solution to this challenge is the use of computational fluid dynamics (CFD) in combination with particle image velocimetry (PIV),which will be the future trend in the investigation of solar thermal systems. The aim of this work is to give an overview of the status of the CFD...
Use of CFD in development of intake ports for diesel engines
International Nuclear Information System (INIS)
Alcenius, T.
2002-01-01
The design of intake ports for diesel engines is difficult due to the many competing requirements of the cylinder head design. When the concept design is completed, the typical course for verification and optimization of the port is through steady state flow testing. In the past, optimization of the port was considered a 'black art' as the final shape of the port and its performance was tied directly to the experience of the port development engineer. As CFD has been increasingly used to analyze various aspects of engine performance, an obvious area to explore is its use to predict steady state port flow performance prior to fabrication of any test hardware. A study was carried out to evaluate the usefulness of CFD in predicting steady state flow bench results and to provide insight into the fluid mechanics of the port flow to assist in the flow bench development. Port flow testing was carried out on a baseline diesel engine port for a range of valve lifts from zero to just above the maximum valve lift. This experimental test data was used to calculate flow coefficients and swirl ratios (an indicator of mean air motion in the cylinder). Subsequently, CFD models were generated that replicated the flow bench set-up. Three valve lifts across the valve lift range were chosen for the comparison. Results of the analysis were used to calculate flow coefficients and swirl ratios. Computed results were then compared to the experiments to determine their accuracy and a detailed review of the CFD results was conducted to understand the flow in the port. Modifications were made to the port from recommendations made based on the CFD results. The ports were then retested to determine the effectiveness of the recommendations. Finally, the results are discussed as to their meaning and usefulness for design programs. (author)
Habilidades pre-escolares de los niños nacidos prematuramente y con bajo peso
Sasha A. Martínez-Espiet; Irene Sumaza Laborde; Leila Crespo Fernández; Maribel Campos Rivera; Frances Boulon Díaz
2016-01-01
RESUMEN: El objetivo de este estudio fue conocer el nivel de desarrollo en la etapa pre-escolar de un grupo de niños nacidos prematuramente y con bajo peso. Se evaluó un grupo 20 niños de cuatro años nacidos prematuramente y con bajo peso y un grupo de 20 niños nacidos luego de gestación completada y peso deseado utilizando la prueba de integración visual-motora Beery-Buktenica. Además, se administró el cuestionario del desarrollo Ages and Stages (ASQ-3) a las 40 madres. El análisis estadísti...
Carga de cáncer del departamento de Nariño y subregiones, Colombia, 2010
Directory of Open Access Journals (Sweden)
Elizabeth Trujillo-Montalvo
2014-09-01
Full Text Available Resumen Objetivo: medir la carga de cáncer a partir del indicador Años de Vida Saludables Perdidos (avisa en el Departamento de Nariño y subregiones. Metodología: mediante el uso de avisa, identificar la carga de cáncer en el departamento de Nariño, 2010. Resultados: Los avisa por cáncer en el Departamento de Nariño destacan la emergencia de los tumores de estómago, cuello uterino, mama, próstata, colon y recto, tráquea/bronquios/pulmón, benignos, las leucemias y linfomas, asimismo una suma importante de años de vida perdidos por muerte prematura y de predominio en mujeres. Conclusiones: este es el primer estudio de carga por cáncer de un departamento en Colombia usando una metodología estandarizada, que contribuye al Plan de Salud Departamental de Nariño, Colombia 2013-2015 y al sistema de indicadores del Plan Decenal para el Control del Cáncer. Los cánceres, luego de las enfermedades cardiovasculares, son las causas más importantes de avisa dentro del grupo de enfermedades no transmisibles. Abstract Objective: to measure the burden of cancer using the indicator Disability Adjusted Life Years (dalys. Methodology: the use of the dalys indicator made it possible to identify the burden of cancer in the department of Nariño, 2010. Results: the dalysdue to cancer emphasize the emergency of stomach, cervix, breast, prostate, trachea/bronchus/lung, colon and rectum and benign tumors, as well as leukemias and lymphomas. Similarly, the indicator shows an important amount of years of life lost due to premature death along with a predominance of this issue among women. Conclusions: this is the first study of burden of cancer targeting a department in Colombia using a standardized methodology contributing to the Health Plan of the department of Nariño in Colombia during 2013-2015 and to the indicators system of the Cancer Control Ten-Year Plan. Cancer is ranked second only to cardiovascular diseases as the most important causes of
Directory of Open Access Journals (Sweden)
Lemus, V.
1982-11-01
Full Text Available Not available.En el Instituto de Investigaciones en Materiales de la Universidad Nacional Autónoma de México, se está desarrollando un área de investigación sobre tecnología de materiales y tecnología de sistemas constructivos, la cual está integrada por diversos proyectos encaminados a solucionar problemas relativos a la vivienda. El presente trabajo consiste en el desarrollo de materiales compuestos a base de desechos agrícolas e industriales, con características tales como baja densidad, resistencia adecuada, excelentes propiedades térmicas y acústicas y, fundamentalmente, bajo costo y gran disponibilidad. Los resultados obtenidos son bastante alentadores debido a la durabilidad y resistencia mecánica obtenidos a base del tratamiento proporcionado a la materia orgánica. Se comentan las aplicaciones actuales y futuras de estos nuevos materiales.
Development of a compartment model based on CFD simulations for description of mixing in bioreactors
Directory of Open Access Journals (Sweden)
Crine, M.
2010-01-01
Full Text Available Understanding and modeling the complex interactions between biological reaction and hydrodynamics are a key problem when dealing with bioprocesses. It is fundamental to be able to accurately predict the hydrodynamics behavior of bioreactors of different size and its interaction with the biological reaction. CFD can provide detailed modeling about hydrodynamics and mixing. However, it is computationally intensive, especially when reactions are taken into account. Another way to predict hydrodynamics is the use of "Compartment" or "Multi-zone" models which are much less demanding in computation time than CFD. However, compartments and fluxes between them are often defined by considering global quantities not representative of the flow. To overcome the limitations of these two methods, a solution is to combine compartment modeling and CFD simulations. Therefore, the aim of this study is to develop a methodology in order to propose a compartment model based on CFD simulations of a bioreactor. The flow rate between two compartments can be easily computed from the velocity fields obtained by CFD. The difficulty lies in the definition of the zones in such a way they can be considered as perfectly mixed. The creation of the model compartments from CFD cells can be achieved manually or automatically. The manual zoning consists in aggregating CFD cells according to the user's wish. The automatic zoning defines compartments as regions within which the value of one or several properties are uniform with respect to a given tolerance. Both manual and automatic zoning methods have been developed and compared by simulating the mixing of an inert scalar. For the automatic zoning, several algorithms and different flow properties have been tested as criteria for the compartment creation.
Algas epífitas de Bajo Pepito, Isla Mujeres, Quintana Roo, México
Directory of Open Access Journals (Sweden)
L.I Quan-Young
2006-06-01
Full Text Available Epiphytic algae from Bajo Pepito, Isla Mujeres, Quintana Roo, México. A total of 96 epiphytic algae species were identified from Bajo Pepito, Quintana Roo, México. 60.4% (58 belonged to the Rhodophyta, 19.79% (19 to the Phaeophyta, 16.6% (16 to the Chlorophyta and 3.1% (3 to the Cyanophyta; 49 species (50.5% were found only in one month, while Heterosiphonia crispella was found in all of the sampled months. That species provided the largest contribution to the biomass of epiphytes. During January we registered the greater biommass and richness of epiphytes species, coincidently with high values of host species cover and rainfall. Rev. Biol. Trop. 54(2: 317-328. Epub 2006 Jun 01.
Best Practice Guidelines for the use of CFD in Nuclear Reactor Safety Applications
International Nuclear Information System (INIS)
Mahaffy, J.; Chung, B.; Song, C.; Dubois, F.; Graffard, E.; Ducros, F.; Heitsch, M.; Scheuerer, M.; Henriksson, M.; Komen, E.; Moretti, F.; Morii, T.; Muehlbauer, P.; Rohde, U.; Smith, B. L.; Watanabe, T.; Zigh, G.
2007-01-01
In May 2002, an 'Exploratory Meeting of Experts to Define an Action Plan on the Application of Computational Fluid Dynamics (CFD) Codes to Nuclear Reactor Safety Problems' was held at Aix-en-Provence, France. One of three recommended actions was the formation of this writing group to report on the need for guidelines for use of CFD in single phase Nuclear Reactor Safety (NRS) applications. CSNI approved this writing group at the end of 2002, and work began in March 2003. A final report was submitted to GAMA in September 2004, summarizing existing Best Practice Guidelines (BPG) for CFD, and recommending creation of a BPG document for Nuclear Reactor Safety (NRS) applications. The present document is intended to provide an internally complete set of guidelines for a range of single phase applications of CFD to NRS problems. However, it is not meant to be comprehensive; it is recognized that for any specific application a higher level of specificity is possible on questions of nodalization, model selection, and validation. This document should provide direct guidance on the key considerations in known single phase applications, and general directions for resolving remaining details. The intent is that it will serve as a template for further application specific (e.g. PTS, induced break) BPG documents that will provide much more detailed information and examples. The document begins with a summary of NRS related CFD analysis in countries represented by the authors. Chapter 3 deals with definition of the problem and its solution approach. This includes isolation of the portion of the NRS problem most in need of CFD, and use of a classic thermal hydraulic (TH) safety code to provide boundary conditions for the CFD based upon less detailed simulation of the balance of plant. Chapter 4 provides guidance in choosing between various options, and also discusses use of a transient calculation with tightly coupled CFD and TH codes. Chapter 5 discusses selection of physical
Integrating Multibody Simulation and CFD: toward Complex Multidisciplinary Design Optimization
Pieri, Stefano; Poloni, Carlo; Mühlmeier, Martin
This paper describes the use of integrated multidisciplinary analysis and optimization of a race car model on a predefined circuit. The objective is the definition of the most efficient geometric configuration that can guarantee the lowest lap time. In order to carry out this study it has been necessary to interface the design optimization software modeFRONTIER with the following softwares: CATIA v5, a three dimensional CAD software, used for the definition of the parametric geometry; A.D.A.M.S./Motorsport, a multi-body dynamic simulation software; IcemCFD, a mesh generator, for the automatic generation of the CFD grid; CFX, a Navier-Stokes code, for the fluid-dynamic forces prediction. The process integration gives the possibility to compute, for each geometrical configuration, a set of aerodynamic coefficients that are then used in the multiboby simulation for the computation of the lap time. Finally an automatic optimization procedure is started and the lap-time minimized. The whole process is executed on a Linux cluster running CFD simulations in parallel.
radEq Add-On Module for CFD Solver Loci-CHEM
McCloud, Peter
2013-01-01
Loci-CHEM to be applied to flow velocities where surface radiation due to heating from compression and friction becomes significant. The module adds a radiation equilibrium boundary condition to the computational fluid dynamics (CFD) code to produce accurate results. The module expanded the upper limit for accurate CFD solutions of Loci-CHEM from Mach 4 to Mach 10 based on Space Shuttle Orbiter Re-Entry trajectories. Loci-CHEM already has a very promising architecture and performance, but absence of radiation equilibrium boundary condition limited the application of Loci-CHEM to below Mach 4. The immediate advantage of the add-on module is that it allows Loci-CHEM to work with supersonic flows up to Mach 10. This transformed Loci-CHEM from a rocket engine- heritage CFD code with general subsonic and low-supersonic applications, to an aeroheating code with hypersonic applications. The follow-on advantage of the module is that it is a building block for additional add-on modules that will solve for the heating generated at Mach numbers higher than 10.
Velocities in a Centrifugal PAT Operation: Experiments and CFD Analyses
Directory of Open Access Journals (Sweden)
Mariana Simão
2017-12-01
Full Text Available Velocity profiles originated by a pump as turbine (PAT were measured using an ultrasonic doppler velocimetry (UDV. PAT behavior is influenced by the velocity data. The effect of the rotational speed and the associated flow velocity variations were investigated. This research focuses, particularly, on the velocity profiles achieved for different rotational speeds and discharge values along the impeller since that is where the available hydraulic power is transformed into the mechanical power. Comparisons were made between experimental test results and computational fluid dynamics (CFD simulations. The used CFD model was calibrated and validated using the same conditions as the experimental facility. The numerical simulations showed good approximation with the velocity measurements for different cross-sections along the PAT system. The application of this CFD numerical model and experimental tests contributed to better understanding the system behavior and to reach the best efficiency operating conditions. Improvements in the knowledge about the hydrodynamic flow behavior associated with the velocity triangles contribute to improvements in the PAT concept and operation.
International Nuclear Information System (INIS)
Lee, Gong Hee; Bang, Young Seok; Woo, Sweng Woong; Cheong, Ae Ju; Kim, Do Hyeong; Kang, Min Ku
2013-01-01
As the computer hardware technology develops the license applicants for nuclear power plant use the commercial CFD software with the aim of reducing the excessive conservatism associated with using simplified and conservative analysis tools. Even if some of CFD software developers and its users think that a state of the art CFD software can be used to solve reasonably at least the single-phase nuclear reactor safety problems there is still the limitations and the uncertainties in the calculation result. From a regulatory perspective, Korea Institute of Nuclear Safety (KINS) has been presently conducting the performance assessment of the commercial CFD software for the nuclear reactor safety problems. In this study, in order to examine the prediction performance of the commercial CFD software with the porous model in the analysis of the scale-down APR+ (Advanced Power Reactor Plus) internal flow, simulation was conducted with the on-board numerical models in ANSYS CFX R.14 and FLUENT R.14. It was concluded that depending on the CFD software the internal flow distribution of the scale-down APR+ was locally some-what different. Although there was a limitation in estimating the prediction performance of the commercial CFD software due to the limited number of the measured data, CFXR.14 showed the more reasonable predicted results in comparison with FLUENT R.14. Meanwhile, due to the difference of discretization methodology, FLUENT R.14 required more computational memory than CFX R.14 for the same grid system. Therefore the CFD software suitable to the available computational resource should be selected for the massive parallel computation. (authors)
Directory of Open Access Journals (Sweden)
Juan Pablo Castrellón-Torres
2015-01-01
Full Text Available Una de las necesidades más apremiantes del sector primario es el desarrollo de métodos, herramie ntas, modelos y técnicas para u na gestión adecuada y eficiente de productos perecederos a lo largo de Cadenas de Suministro (SC, pa rticularmente enfocados en lo s servicios logísticos especializad os (ThirdParty Logistics 3PL como la consolid ación de carga. Esta estrategia de coordinación busca la alineación de los agentes y procesos para la eficiente manipulación de carga, minimi zando costos y permitiendo el uso adecuado de capacidades de medios de transporte. La cont ribución de este artículo se centra en el modelado y análisis de beneficios de las estrategias de consolidación de carga en el contexto de Cadenas de Suministro Agrícolas (ASC a través de la simulación. Los resultados de la simulación de eventos discretos, evaluando un producto commodity en tres diferentes escen arios, prueba los beneficios de esta e strategia de coordinación al reducir el nú mero anual de envíos de 1732 a 725 en un contex to de logística urbana e incrementando los nivel es de utilización de la flota hasta el 71%.
Carga limite para juntas mecânicas em laminados de fibra de carbono
Arthur Chaves de Mas Santacreu
1989-01-01
Neste trabalho são testadas várias juntas parafusadas com laminados de fibra de carbono. São investigadas as influências dos parâmetros geométricos e dos parâmetros de constituição do laminado no comportamento da curva carga versus deformação do furo carregado. Paralelamente é desenvolvido um modelo de elementos finitos linear elástico para calcular a deformação do furo carregado a partir das propriedades mecânicas do material e da geometria da junta. É proposto um critério de previsão de car...
Arnera, Patricia Liliana; Beroqui, Mario César; Bianchi Lastra, Raúl E.; Molina Milyus, Roberto D.; Gaido, Roberto
1995-01-01
Se midieron y registraron una gran cantidad de transitorios de la frecuencia del sistema provocados por eventos conocidos como pérdida de generadores y carga y descarga de bombas de la estación generadora de bombeo de Río Grande ubicada en la provincia de Córdoba, Argentina. Además se registraron variaciones rápidas de la potencia de carga en distintos nodos de la red. Con estas mediciones se procedió a estimar el coeficiente de sensibilidad de la carga a la frecuencia y a evaluar las desv...
Energy Technology Data Exchange (ETDEWEB)
Lee, S.
2011-05-05
The Savannah River Remediation (SRR) Organization requested that Savannah River National Laboratory (SRNL) develop a Computational Fluid Dynamics (CFD) method to mix and blend the miscible contents of the blend tanks to ensure the contents are properly blended before they are transferred from the blend tank; such as, Tank 50H, to the Salt Waste Processing Facility (SWPF) feed tank. The work described here consists of two modeling areas. They are the mixing modeling analysis during miscible liquid blending operation, and the flow pattern analysis during transfer operation of the blended liquid. The transient CFD governing equations consisting of three momentum equations, one mass balance, two turbulence transport equations for kinetic energy and dissipation rate, and one species transport were solved by an iterative technique until the species concentrations of tank fluid were in equilibrium. The steady-state flow solutions for the entire tank fluid were used for flow pattern analysis, for velocity scaling analysis, and the initial conditions for transient blending calculations. A series of the modeling calculations were performed to estimate the blending times for various jet flow conditions, and to investigate the impact of the cooling coils on the blending time of the tank contents. The modeling results were benchmarked against the pilot scale test results. All of the flow and mixing models were performed with the nozzles installed at the mid-elevation, and parallel to the tank wall. From the CFD modeling calculations, the main results are summarized as follows: (1) The benchmark analyses for the CFD flow velocity and blending models demonstrate their consistency with Engineering Development Laboratory (EDL) and literature test results in terms of local velocity measurements and experimental observations. Thus, an application of the established criterion to SRS full scale tank will provide a better, physically-based estimate of the required mixing time, and
Directory of Open Access Journals (Sweden)
Jonez Fidalski
2015-06-01
Full Text Available O manejo da altura de pastejo das forrageiras pelos bovinos pode comprometer os atributos físicos do solo. O objetivo deste trabalho foi avaliar a influência da altura de pastejo de braquiária (Urochloa ruziziensis e a carga animal média, após três anos de sistema integração lavoura-pecuária com soja, nos atributos físicos de um Latossolo Vermelho distrófico típico. O delineamento experimental foi de blocos casualizados, com três repetições. Cinco tratamentos com 10, 20, 30 e 40 cm de altura de pastejo, após 84 dias de pastejo contínuo mantidos com carga variável de bovinos, e um tratamento testemunha sem pastejo foram avaliados em parcelas experimentais de 1 ha. Em novembro de 2012, após o terceiro período de pastejo, com carga animal média de 1.262, 919, 892 e 724 kg ha-1 de peso vivo, respectivamente, para as alturas de pastejo de 10, 20, 30 e 40 cm, coletaram-se amostras indeformadas de solo nas camadas de 0-10, 10-20 e 20-30 cm, as quais foram utilizadas para determinar as curvas de retenção de água e de resistência do solo à penetração e a densidade do solo (Ds, bem como para calcular o intervalo hídrico ótimo (IHO. A menor Ds ocorreu na camada de 0-10 cm para a altura de pastejo de 31 cm da braquiária que correspondeu a 72 % da carga animal máxima. O maior IHO ocorreu na camada de 10-20 cm para a altura de pastejo de 23 cm da braquiária que correspondeu a 83 % da carga animal máxima. O manejo da altura de pastejo da braquiária foi limitado em 23 cm pela maior carga animal e melhores atributos físicos na camada de 10-20 cm do Latossolo Vermelho distrófico típico.
Natural ventilation of a generic cask under a transport hood - CFD and analytical modelling
Energy Technology Data Exchange (ETDEWEB)
Powell, D.; Davies, G.; Tso, C.F. [Arup, London (United Kingdom)
2004-07-01
In comparison with finite element simulation for structural and thermal behaviour, the use of computational fluid dynamics technique (hereafter CFD) to analyse, predict and design air and heat flow in package design is relatively novel. Arup has been using CFD techniques to investigate fluid and heat flow, and to use it as a tool to design fluid and heat flow across a broad spectrum of industries for over fifteen years. In order demonstrate the power of the technique and its benefits, the airflow and heat flow characteristics around a transport package during transit under a transport hood has been evaluated using the CFD technique. This paper presents the scenario, the model, the analysis technique and the results of this analysis. Comparison with test results is probably the best way to validate a CFD analysis. In the absence of test results, the analysis was verified by comparison with hand calculation solutions. The scenario as it stands is too complex and hand calculation solution cannot describe the scenario sufficiently. However, hand calculation solutions could be derived for simplified version of the scenario against which CFD analysis of the simplified scenario can be compared. The second half of this paper describes the verification out.
Natural ventilation of a generic cask under a transport hood - CFD and analytical modelling
International Nuclear Information System (INIS)
Powell, D.; Davies, G.; Tso, C.F.
2004-01-01
In comparison with finite element simulation for structural and thermal behaviour, the use of computational fluid dynamics technique (hereafter CFD) to analyse, predict and design air and heat flow in package design is relatively novel. Arup has been using CFD techniques to investigate fluid and heat flow, and to use it as a tool to design fluid and heat flow across a broad spectrum of industries for over fifteen years. In order demonstrate the power of the technique and its benefits, the airflow and heat flow characteristics around a transport package during transit under a transport hood has been evaluated using the CFD technique. This paper presents the scenario, the model, the analysis technique and the results of this analysis. Comparison with test results is probably the best way to validate a CFD analysis. In the absence of test results, the analysis was verified by comparison with hand calculation solutions. The scenario as it stands is too complex and hand calculation solution cannot describe the scenario sufficiently. However, hand calculation solutions could be derived for simplified version of the scenario against which CFD analysis of the simplified scenario can be compared. The second half of this paper describes the verification out
Autoestima en adolescentes con bajo rendimiento escolar a través del psicodiagnóstico de Rorschach
Directory of Open Access Journals (Sweden)
Magally de Garrido-Lecca
1997-12-01
Full Text Available El objetivo fue determinar si existen diferencias en la autoestima de adolescentes con bajo rendimiento escolar comparados con los de un rendimiento promedio o superior. Los participantes fueron 60 adolescentes, entre 13 y 16 años, de ambos sexos, con un C.I. promedio o superior al promedio, de los cuales 30 presentaban un bajo rendimiento escolar (grupo de estudio y 30 un buen rendimiento (grupo contraste. Se administró el WISCR para determinar el C.I. y el Rorschach según el SC de Exner para evaluar la autoestima. Los resultados mostraron que el Rorschach es adecuado para evaluar la autoestima. Asimismo existe una diferencia significativa en la autoestima de adolescentes con bajo rendimiento como resultado de sus déficits afectivos, en comparación con los de alto rendimiento.
CFD simulation of neutral ABL flows; Atmospheric Boundary Layer
Energy Technology Data Exchange (ETDEWEB)
Xiaodong Zhang
2009-04-15
This work is to evaluate the CFD prediction of Atmospheric Boundary Layer flow field over different terrains employing Fluent 6.3 software. How accurate the simulation could achieve depend on following aspects: viscous model, wall functions, agreement of CFD model with inlet wind velocity profile and top boundary condition. Fluent employ wall function roughness modifications based on data from experiments with sand grain roughened pipes and channels, describe wall adjacent zone with Roughness Height (Ks) instead of Roughness Length (z{sub 0}). In a CFD simulation of ABL flow, the mean wind velocity profile is generally described with either a logarithmic equation by the presence of aerodynamic roughness length z{sub 0} or an exponential equation by the presence of exponent. As indicated by some former researchers, the disagreement between wall function model and ABL velocity profile description will result in some undesirable gradient along flow direction. There are some methods to improve the simulation model in literatures, some of them are discussed in this report, but none of those remedial methods are perfect to eliminate the streamwise gradients in mean wind speed and turbulence, as EllipSys3D could do. In this paper, a new near wall treatment function is designed, which, in some degree, can correct the horizontal gradients problem. Based on the corrected model constants and near wall treatment function, a simulation of Askervein Hill is carried out. The wind condition is neutrally stratified ABL and the measurements are best documented until now. Comparison with measured data shows that the CFD model can well predict the velocity field and relative turbulence kinetic energy field. Furthermore, a series of artificial complex terrains are designed, and some of the main simulation results are reported. (au)
CFD modelling of condensers for freeze-drying processes
Indian Academy of Sciences (India)
Freeze-drying; condenser; CFD simulation; mathematical modelling; ... it is used for the stabilization and storage of delicate, heat-sensitive materials .... The effect of the surface mass transfer has been included in the continuity equation and.
The status of research on CFD-PBM simulation of liquid-liquid two-phase flow in extraction columns
International Nuclear Information System (INIS)
Li Shaowei; Jing Shan; Wu Qiulin; Zhang Qi
2012-01-01
Computational fluid dynamics (CFD) simulation has gained more and more interest in the chemical engineering researchers and is becoming a useful tool for the chemical engineering research. The research on liquid-liquid two-phase flow CFD simulation in extraction columns is now in its initial stage. There is much work to do for the developing of this research field. The purpose of this article is to review the CFD simulation methods for two-phase flow in extraction column. The population balance model (PBM) is detailedly described in this article because it is the main method used in the two-phase flow CFD simulation currently. Then some examples for the two-phase flow simulation in extraction columns are briefly introduced. The strategy for the research on CFD simulation of two-phase flow in extraction columns is suggested at last. (authors)
Multiphase flow in porous media using CFD
DEFF Research Database (Denmark)
Hemmingsen, Casper Schytte; Walther, Jens Honore
. This approach is widely used for single phase flow, but not for multiphase flow in porous media. This might be due to the complexity of introducing relative permeability and capillary pressure in the CFD solver.The introduction of relative permeability and capillary pressure may cause numerical instabilities...
Numerical CFD Comparison of Lillgrund Employing RANS
DEFF Research Database (Denmark)
Simisiroglou, N.; Breton, S.-P.; Crasto, G.
2014-01-01
The following article will validate the results obtained using the actuator disc method in the state of the art numerical Computational Fluid Dynamic (CFD) tool WindSim using on-site measurements from the offshore wind farm Lillgrund. WindSim solves the mass, momentum and energy conservation...
de Boer, Anne H; Hagedoorn, Paul; Woolhouse, Robert; Wynn, Ed
2012-09-01
To use computational fluid dynamics (CFD) for evaluating and understanding the performance of the high-dose disposable Twincer™ dry powder inhaler, as well as to learn the effect of design modifications on dose entrainment, powder dispersion and retention behaviour. Comparison of predicted flow and particle behaviour from CFD computations with experimental data obtained with cascade impactor and laser diffraction analysis. Inhaler resistance, flow split, particle trajectories and particle residence times can well be predicted with CFD for a multiple classifier based inhaler like the Twincer™. CFD computations showed that the flow split of the Twincer™ is independent of the pressure drop across the inhaler and that the total flow rate can be decreased without affecting the dispersion efficacy or retention behaviour. They also showed that classifier symmetry can be improved by reducing the resistance of one of the classifier bypass channels, which for the current concept does not contribute to the swirl in the classifier chamber. CFD is a highly valuable tool for development and optimisation of dry powder inhalers. CFD can assist adapting the inhaler design to specific physico-chemical properties of the drug formulation with respect to dispersion and retention behaviour. © 2012 The Authors. JPP © 2012 Royal Pharmaceutical Society.
CFD simulation on reactor flow mixing phenomena
International Nuclear Information System (INIS)
Kwon, T.S.; Kim, K.H.
2016-01-01
A pre-test calculation for multi-dimensional flow mixing in a reactor core and downcomer has been studied using a CFD code. To study the effects of Reactor Coolant Pump (RCP) and core zone on the boron mixing behaviors in a lower downcomer and core inlet, a 1/5-scale CFD model of flow mixing test facility for the APR+ reference plant was simulated. The flow paths of the 1/5-scale model were scaled down by the linear scaling method. The aspect ratio (L/D) of all flow paths was preserved to 1. To preserve a dynamic similarity, the ratio of Euler number was also preserved to 1. A single phase water flow at low pressure and temperature conditions was considered in this calculation. The calculation shows that the asymmetric effect driven by RCPs shifted the high velocity field to the failed pump's flow zone. The borated water flow zone at the core inlet was also shifted to the failed RCP side. (author)
Energy Technology Data Exchange (ETDEWEB)
Bellivier, A.
2004-05-15
For 3D modelling of thermo-aeraulics in building using field codes, it is necessary to reduce the computing time in order to model increasingly larger volumes. The solution suggested in this study is to couple two modelling: a zonal approach and a CFD approach. The first part of the work that was carried out is the setting of a simplified CFD modelling. We propose rules for use of coarse grids, a constant effective viscosity law and adapted coefficients for heat exchange in the framework of building thermo-aeraulics. The second part of this work concerns the creation of fluid Macro-Elements and their coupling with a calculation of CFD finite volume type. Depending on the boundary conditions of the problem, a local description of the driving flow is proposed via the installation and use of semi-empirical evolution laws. The Macro-Elements is then inserted in CFD computation: the values of velocity calculated by the evolution laws are imposed on the CFD cells corresponding to the Macro-Element. We use these two approaches on five cases representative of thermo-aeraulics in buildings. The results are compared with experimental data and with traditional RANS simulations. We highlight the significant gain of time that our approach allows while preserving a good quality of numerical results. (author)
Overview of Computational Fluid Dynamics (CFD) simulation of stirred vessel
International Nuclear Information System (INIS)
Mohd Rizal Mamat; Azraf Azman; Anwar Abdul Rahman; Noraishah Othman
2010-01-01
Stirred vessel is one of many widely used equipment in industrial process and chemical industry. The design of stirred vessel typically follows a certain standard chemical engineering practice that may also involve empirical data acquired from experiments. However the design may still take a different route which is computational engineering simulation and analysis. CFD has been identified as one of the possible tools for such purposes. CFD enables the flow fields variables such as velocity, temperature and pressure in the whole computational domain to be obtained and as such it presents an advantage over the experimental setup. (author)
CFD optimization of continuous stirred-tank (CSTR) reactor for biohydrogen production.
Ding, Jie; Wang, Xu; Zhou, Xue-Fei; Ren, Nan-Qi; Guo, Wan-Qian
2010-09-01
There has been little work on the optimal configuration of biohydrogen production reactors. This paper describes three-dimensional computational fluid dynamics (CFD) simulations of gas-liquid flow in a laboratory-scale continuous stirred-tank reactor used for biohydrogen production. To evaluate the role of hydrodynamics in reactor design and optimize the reactor configuration, an optimized impeller design has been constructed and validated with CFD simulations of the normal and optimized impeller over a range of speeds and the numerical results were also validated by examination of residence time distribution. By integrating the CFD simulation with an ethanol-type fermentation process experiment, it was shown that impellers with different type and speed generated different flow patterns, and hence offered different efficiencies for biohydrogen production. The hydrodynamic behavior of the optimized impeller at speeds between 50 and 70 rev/min is most suited for economical biohydrogen production. Copyright 2010 Elsevier Ltd. All rights reserved.
Preliminary CFD analysis methodology for flow in a LFR fuel assembly
International Nuclear Information System (INIS)
Catana, A.; Ioan, M.; Serbanel, M.
2013-01-01
In this paper a preliminary Computational Fluid Dynamics (CFD) analysis was performed in order to setup a methodology to be used for more complex coolant flow analysis inside ALFRED nuclear reactor fuel assembly. The core contains 171 separated fuel assembly, each consisting in a hexagonal array of 127 fuel rods. Three honey comb spacer grids are proposed along fuel rods with the aim to keep flow geometry intact during reactor operation. The main goal of this paper is to compute some hydraulic parameters: pressure, velocity, wall shear stress and turbulence parameters with and without spacer grids. In this analysis we consider an adiabatic case, so far no heat transfer is considered but we pave the road toward more complex thermo hydraulic analysis for ALFRED (LFR in general). The CAELINUX CFD distribution was used with its main components: Salome-Meca (for geometry and mesh) and Code-Saturne as mono-phase CFD solver. Paraview and Visist Postprocessors were used for data extraction and graphical displays. (authors)
Comparing different CFD wind turbine modelling approaches with wind tunnel measurements
International Nuclear Information System (INIS)
Kalvig, Siri; Hjertager, Bjørn; Manger, Eirik
2014-01-01
The performance of a model wind turbine is simulated with three different CFD methods: actuator disk, actuator line and a fully resolved rotor. The simulations are compared with each other and with measurements from a wind tunnel experiment. The actuator disk is the least accurate and most cost-efficient, and the fully resolved rotor is the most accurate and least cost-efficient. The actuator line method is believed to lie in between the two ends of the scale. The fully resolved rotor produces superior wake velocity results compared to the actuator models. On average it also produces better results for the force predictions, although the actuator line method had a slightly better match for the design tip speed. The open source CFD tool box, OpenFOAM, was used for the actuator disk and actuator line calculations, whereas the market leading commercial CFD code, ANSYS/FLUENT, was used for the fully resolved rotor approach
Directory of Open Access Journals (Sweden)
Ellen Maria Pires Siqueira
2015-06-01
Full Text Available Objetivo: Correlacionar gravidade do paciente e carga de trabalho da equipe de enfermagem, utilizando os índices Simplified Acute Psysiology Score (SAPS3 e Nursing Activities Score (NAS e compará-los entre três subgrupos: cardiológicos, neurológicos e gerais. Métodos: Coorte prospectivo, em uma Unidade de Terapia Intensiva de hospital privado de São Paulo, entre agosto a outubro de 2011. Resultados: Foram acompanhados 195 pacientes, 57,9% do sexo masculino, mediana de idade 69 anos. Correlação moderada entre NAS e SAPS3 no subgrupo neurológico (p = 0,02; r = 0,430. SAPS3 do subgrupo geral foi maior comparado ao subgrupo neurológico (p = 0,002. O NAS foi maior no subgrupo geral quando comparado ao subgrupo cardiológico (p = 0,001. Conclusão: Houve correlação moderada entre a gravidade de pacientes neurológicos e a carga de trabalho de enfermagem. A gravidade e a carga de trabalho de enfermagem no subgrupo de pacientes gerais foram maiores em relação aos pacientes neurológicos e cardiológicos, respectivamente.
Directory of Open Access Journals (Sweden)
Hugo Opazo Mora
2008-06-01
Full Text Available This paper approaches the minimal loss reconfiguration problem, taking into account the load variations of the systems, through a stochastic reconfiguration process. The Monte Carlo method is used to consider the natural load variation. A normal probability function is used to generate aleatory load levels in the nodes. The results of this work show the existence of a set of branches that are frequently eliminated. This generates a tree branch set that best represents the universal randomness of the load. We call it "Expected Branch Set (EBS". The topology associated to the EBS coincides with that obtained using the average demand values. This makes it unnecessary to generate a considerable number of tests to find that topology that best considers the load variation. The proposed algorithm was applied to two test networks and to a large real network.Este trabajo se plantea la reconfiguración a mínimas pérdidas, tomando en cuenta las variaciones de carga del sistema, a través de un proceso de reconfiguración estocástico. El Método de Monte Carlo es usado para considerar las variaciones naturales de la carga, utilizando una función de probabilidad normal para generar niveles aleatorios de carga en los nudos. Los resultados de este trabajo muestran la existencia de un conjunto de ramas que son frecuentemente eliminadas en el proceso de reconfiguración. Esto genera un conjunto de ramas de un árbol, las que mejor representan aleatoriedad universal de la carga. La topología obtenida la denominamos "Conjunto de Ramas Esperadas" (Expected Branch Set, EBS. La topología asociada al EBS es casi similar a la topología obtenida usando los valores de demanda promedio. Esto hace innecesario el realizar un considerable número de pruebas para encontrar la topología que mejor considera las variaciones de carga. El algoritmo propuesto fue aplicado a dos sistemas de prueba y a un sistema real de gran envergadura.
CFD application to advanced design for high efficiency spacer grid
International Nuclear Information System (INIS)
Ikeda, Kazuo
2014-01-01
Highlights: • A new LDV was developed to investigate the local velocity in a rod bundle and inside a spacer grid. • The design information that utilizes for high efficiency spacer grid has been obtained. • CFD methodology that predicts flow field in a PWR fuel has been developed. • The high efficiency spacer grid was designed using the CFD methodology. - Abstract: Pressurized water reactor (PWR) fuels have been developed to meet the needs of the market. A spacer grid is a key component to improve thermal hydraulic performance of a PWR fuel assembly. Mixing structures (vanes) of a spacer grid promote coolant mixing and enhance heat removal from fuel rods. A larger mixing vane would improve mixing effect, which would increase the departure from nucleate boiling (DNB) benefit for fuel. However, the increased pressure loss at large mixing vanes would reduce the coolant flow at the mixed fuel core, which would reduce the DNB margin. The solution is to develop a spacer grid whose pressure loss is equal to or less than the current spacer grid and that has higher critical heat flux (CHF) performance. For this reason, a requirement of design tool for predicting the pressure loss and CHF performance of spacer grids has been increased. The author and co-workers have been worked for development of high efficiency spacer grid using Computational Fluid Dynamics (CFD) for nearly 20 years. A new laser Doppler velocimetry (LDV), which is miniaturized with fiber optics embedded in a fuel cladding, was developed to investigate the local velocity profile in a rod bundle and inside a spacer grid. The rod-embedded fiber LDV (rod LDV) can be inserted in an arbitrary grid cell instead of a fuel rod, and has the advantage of not disturbing the flow field since it is the same shape as a fuel rod. The probe volume of the rod LDV is small enough to measure spatial velocity profile in a rod gap and inside a spacer grid. According to benchmark experiments such as flow velocity
CFD application to advanced design for high efficiency spacer grid
Energy Technology Data Exchange (ETDEWEB)
Ikeda, Kazuo, E-mail: kazuo3_ikeda@ndc.mhi.co.jp
2014-11-15
Highlights: • A new LDV was developed to investigate the local velocity in a rod bundle and inside a spacer grid. • The design information that utilizes for high efficiency spacer grid has been obtained. • CFD methodology that predicts flow field in a PWR fuel has been developed. • The high efficiency spacer grid was designed using the CFD methodology. - Abstract: Pressurized water reactor (PWR) fuels have been developed to meet the needs of the market. A spacer grid is a key component to improve thermal hydraulic performance of a PWR fuel assembly. Mixing structures (vanes) of a spacer grid promote coolant mixing and enhance heat removal from fuel rods. A larger mixing vane would improve mixing effect, which would increase the departure from nucleate boiling (DNB) benefit for fuel. However, the increased pressure loss at large mixing vanes would reduce the coolant flow at the mixed fuel core, which would reduce the DNB margin. The solution is to develop a spacer grid whose pressure loss is equal to or less than the current spacer grid and that has higher critical heat flux (CHF) performance. For this reason, a requirement of design tool for predicting the pressure loss and CHF performance of spacer grids has been increased. The author and co-workers have been worked for development of high efficiency spacer grid using Computational Fluid Dynamics (CFD) for nearly 20 years. A new laser Doppler velocimetry (LDV), which is miniaturized with fiber optics embedded in a fuel cladding, was developed to investigate the local velocity profile in a rod bundle and inside a spacer grid. The rod-embedded fiber LDV (rod LDV) can be inserted in an arbitrary grid cell instead of a fuel rod, and has the advantage of not disturbing the flow field since it is the same shape as a fuel rod. The probe volume of the rod LDV is small enough to measure spatial velocity profile in a rod gap and inside a spacer grid. According to benchmark experiments such as flow velocity
Using CFD as Rocket Injector Design Tool: Recent Progress at Marshall Space Flight Center
Tucker, Kevin; West, Jeff; Williams, Robert; Lin, Jeff; Rocker, Marvin; Canabal, Francisco; Robles, Bryan; Garcia, Robert; Chenoweth, James
2003-01-01
The choice of tools used for injector design is in a transitional phase between exclusive reliance on the empirically based correlations and extensive use of computational fluid dynamics (CFD). The Next Generation Launch Technology (NGLT) Program goals emphasizing lower costs and increased reliability have produced a need to enable CFD as an injector design tool in a shorter time frame. This is the primary objective of the Staged Combustor Injector Technology Task currently under way at Marshall Space Flight Center (MSFC). The documentation of this effort begins with a very brief status of current injector design tools. MSFC's vision for use of CFD as a tool for combustion devices design is stated and discussed with emphasis on the injector. The concept of the Simulation Readiness Level (SRL), comprised of solution fidelity, robustness and accuracy, is introduced and discussed. This quantitative measurement is used to establish the gap between the current state of demonstrated capability and that necessary for regular use in the design process. MSFC's view of the validation process is presented and issues associated with obtaining the necessary data are noted and discussed. Three current experimental efforts aimed at generating validation data are presented. The importance of uncertainty analysis to understand the data quality is also demonstrated. First, a brief status of current injector design tools is provided as context for the current effort. Next, the MSFC vision for using CFD as an injector design tool is stated. A generic CFD-based injector design methodology is also outlined and briefly discussed. Three areas where MSFC is using injector CFD analyses for program support will be discussed. These include the Integrated Powerhead Development (IPD) engine which uses hydrogen and oxygen propellants in a full flow staged combustion (FFSC) cycle and the TR-107 and the RS84 engine both of which use RP-1 and oxygen in an ORSC cycle. Finally, an attempt is made to
Vulović, Aleksandra; Šušteršič, Tijana; Cvijić, Sandra; Ibrić, Svetlana; Filipović, Nenad
2018-02-15
One of the critical components of the respiratory drug delivery is the manner in which the inhaled aerosol is deposited in respiratory tract compartments. Depending on formulation properties, device characteristics and breathing pattern, only a certain fraction of the dose will reach the target site in the lungs, while the rest of the drug will deposit in the inhalation device or in the mouth-throat region. The aim of this study was to link the Computational fluid dynamics (CFD) with physiologically-based pharmacokinetic (PBPK) modelling in order to predict aerolisolization of different dry powder formulations, and estimate concomitant in vivo deposition and absorption of amiloride hydrochloride. Drug physicochemical properties were experimentally determined and used as inputs for the CFD simulations of particle flow in the generated 3D geometric model of Aerolizer® dry powder inhaler (DPI). CFD simulations were used to simulate air flow through Aerolizer® inhaler and Discrete Phase Method (DPM) was used to simulate aerosol particles deposition within the fluid domain. The simulated values for the percent emitted dose were comparable to the values obtained using Andersen cascade impactor (ACI). However, CFD predictions indicated that aerosolized DPI have smaller particle size and narrower size distribution than assumed based on ACI measurements. Comparison with the literature in vivo data revealed that the constructed drug-specific PBPK model was able to capture amiloride absorption pattern following oral and inhalation administration. The PBPK simulation results, based on the CFD generated particle distribution data as input, illustrated the influence of formulation properties on the expected drug plasma concentration profiles. The model also predicted the influence of potential changes in physiological parameters on the extent of inhaled amiloride absorption. Overall, this study demonstrated the potential of the combined CFD-PBPK approach to model inhaled drug
Toward a CFD-grade database addressing LWR containment phenomena
Energy Technology Data Exchange (ETDEWEB)
Paladino, Domenico, E-mail: domenico.paladino@psi.ch [Laboratory for Thermal-Hydraulics, Nuclear Energy and Safety Department, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland); Andreani, Michele; Zboray, Robert; Dreier, Joerg [Laboratory for Thermal-Hydraulics, Nuclear Energy and Safety Department, Paul Scherrer Institut, CH-5232 Villigen PSI (Switzerland)
2012-12-15
Highlights: Black-Right-Pointing-Pointer The SETH-2 PANDA tests have supplied data with CFD-grade on plumes and jets at large-scale. Black-Right-Pointing-Pointer The PANDA tests have contributed to the understanding of phenomena with high safety relevance for LWRs. Black-Right-Pointing-Pointer The analytical activities related increased confidence in the use of various computational tools for safety analysis. - Abstract: The large-scale, multi-compartment PANDA facility (located at PSI in Switzerland) is one of the state-of-the-art facilities which is continuously upgraded to progressively match the requirements of CFD-grade experiments. Within the OECD/SETH projects, the PANDA facility has been used for the creation of an experimental database on basic containment phenomena e.g. gas mixing, transport, stratification, condensation. In the PANDA tests, these phenomena are driven by large scale plumes or jets. In the paper is presented a selection of the SETH PANDA experimental results. Examples of analytical activities performed at PSI using the GOTHIC, CFX-4 and CFX-5 codes will be used to illustrate how the spatial and temporal resolutions of the measurement grid in PANDA tests are adequate for CFD code (and advanced containment codes) assessment and validation purposes.
cultivadas bajo un gradiente de sombra
Directory of Open Access Journals (Sweden)
Marco V. Gutiérrez
2007-01-01
Full Text Available Se evaluó el crecimiento de 9 especies de palmas cultivadas bajo un gradiente de sombra producido por mallas de polipropileno negro de 40, 50, 60, 70 y 80% de sombra, más un tratamiento de malla aluminizada de 70%, y uno con plantas a pleno sol. Las especies evaluadas fueron Caryota mitis (cola de pez, Chamaedorea costaricana (pacaya, Chamaedorea tepejilote (tepejilote, Dypsis lutescens (areca, Licuala elegans (licuala, Phoenix roebelenii (fénix, Ptychosperma macarthurii (palma macarthur, Roystonea regia (palma real, y Veitchia merrillii (navideña. Se midió la altura de las plantas, la longitud de las hojas maduras, y el número de hojas cosechadas, durante 5 cosechas por 2 años. En general, la altura de las plantas y la longitud de las hojas fueron menores a 0-40% de sombra, se incrementaron a 50-70%, y decrecieron a 80%. C. mitis, C. tepejilote, L. elegans y P. macarthurii, se comportaron como especies obligadas de sombra y no sobrevivieron a pleno sol. C. costaricana y D. lutescens sobrevivieron a plena exposición solar, y su crecimiento alcanzó valores máximos a 50-60%. P. roebelenii, R. regia, y V. merrillii mostraron un crecimiento reducido a 0-40%, pero éste mejoró bajo los demás niveles de sombra a lo largo del gradiente. En general, 1-2 años es un periodo apropiado para el cultivo de palmas de crecimiento rápido (R. regia, Chamedorea spp., D. lutescens en casas de mallas. Palmas de lento crecimiento (L.elegans pueden permanecer 3-5 años en una casa de sombra. Se discute estrategias para el uso de gradientes de sombra en el tiempo y en el espacio, según la utilidad y los requerimientos de las especies, los requisitos establecidos por el mercado, y el ciclo de producción del material vegetal.
Pilot-in-the-Loop CFD Method Development
2017-02-01
linear behavior of the rotor/terrain interactions. However these fluctuations are not as strong as we saw in the hover IGE cases. Helicopter shows...West Palm Beach, FL, May 2016. Oruc, I., Horn, J.F., Shipman, J., and Shenoy, R., “Coupled Flight Dynamics and CFD Simulations of the
Investigation on the Use of a Multiphase Eulerian CFD solver to simulate breaking waves
DEFF Research Database (Denmark)
Tomaselli, Pietro D.; Christensen, Erik Damgaard
2015-01-01
investigation on a CFD model capable of handling this problem. The model is based on a solver, available in the open-source CFD toolkit OpenFOAM, which combines the Eulerian multi-fluid approach for dispersed flows with a numerical interface sharpening method. The solver, enhanced with additional formulations...
CFD Analysis of Scale Effects on Conventional and Tip-Modified Propellers
DEFF Research Database (Denmark)
Shin, Keun Woo; Andersen, Poul
2017-01-01
Full-scale propeller performance is traditionally predictedby scaling model-scale test results, but the traditionalscaling methods do not take into account hydrodynamicdistinctions of tip-modified propellers in full-scaleperformance. An open-water CFD analysis is made onscale effects of tip...... the transition model shows that laminar and transitionalflow modeling is crucial in model-scale computations.Grid-independent solutions at model and full scale areachieved by grid verification studies. The CFD analysis of scale effects shows that theefficiency gain of the tip-modified propeller is increasedat...
Measurement and CFD calculation of spacer loss coefficient for a tight-lattice fuel bundle
International Nuclear Information System (INIS)
In, Wang Kee; Shin, Chang Hwan; Kwack, Young Kyun; Lee, Chi Young
2015-01-01
Highlights: • Experiment and CFD analysis evaluated the pressure drop in a spacer grid. • The measurement and CFD errors for the spacer loss coefficient were estimated. • The spacer loss coefficient for the dual-cooled annular fuel bundle was determined. • The CFD prediction agrees with the measured spacer loss coefficient within 8%. - Abstract: An experiment and computational fluid dynamics (CFD) analysis were performed to evaluate the pressure drop in a spacer grid for a dual-cooled annular fuel (DCAF) bundle. The DCAF bundle for the Korean optimum power reactor (OPR1000) is a 12 × 12 tight-lattice rod array with a pitch-to-diameter ratio of 1.08 owing to a larger outer diameter of the annular fuel rod. An experiment was conducted to measure the pressure drop in spacer grid for the DCAF bundle. The test bundle is a full-size 12 × 12 rod bundle with 11 spacer grid. The test condition covers a Reynolds number range of 2 × 10 4 –2 × 10 5 by changing the temperature and flow rate of water. A CFD analysis was also performed to predict the pressure drop through a spacer grid using the full-size and partial bundle models. The pressure drop and loss coefficient of a spacer grid were predicted and compared with the experimental results. The CFD predictions of spacer pressure drop and loss coefficient agree with the measured values within 8%. The spacer loss coefficient for the DCAF bundle is estimated to be approximately 1.50 at a nominal operating condition of OPR1000, i.e., Re = 4 × 10 5
CFD validation of a supercritical water flow for SCWR design heat and mass fluxes
International Nuclear Information System (INIS)
Roelofs, F.; Lycklama a Nijeholt, J.A.; Komen, E.M.J.; Lowenberg, M.; Starflinger, J.
2007-01-01
The applicability of Computational Fluid Dynamics (CFD) for water under supercritical conditions in supercritical water reactors (SCWR) has still to be verified. In the recent past, CFD validation analyses were performed by various institutes for supercritical water in vertical tubes based on the well known experimental data from Yamagata. However, validation using data from experiments with working conditions closer to the actual operational conditions of such reactors is needed. From a literature survey the experiments performed by Herkenrath are selected to perform validation analyses at higher heat fluxes and a higher mass flux. The accuracy of CFD using RANS (Reynolds Average Navier-Stokes) turbulence modelling for supercritical fluids under conditions close to the operational conditions of a supercritical water reactor is determined. It is concluded that the wall temperature can be predicted by RANS CFD, using the RNG k-ε turbulence model, with accuracy in the range of 5% for heat fluxes up to 1100 kW/m 2 and for a bulk enthalpy up to 2200 kJ/kg. For a bulk enthalpy exceeding 2200 kJ/kg, a significant lower accuracy of the CFD predictions (about 3%) is found for the simulations of the experiments of Yamagata in comparison with the simulations of the experiments of Herkenrath. For these experiments, the accuracy is about 18 per cent. This might be a result of the fact that the CFD analyses do not simulate the flattening of the temperature profile at about 2200 kJ/kg which is found in the experiments of Herkenrath. However, the obtained accuracies ranging from 3% to 18% are still deemed to be acceptable for many design purposes. (authors)
Energy Technology Data Exchange (ETDEWEB)
Pena-Monferrer, C.; Miquel veyrat, A.; Munoz-Cobo, J. L.; Chiva Vicent, S.
2016-08-01
In the recent years, due, among others, the slowing down of the nuclear industry, investment in the development and validation of CFD codes, applied specifically to the problems of the nuclear industry has been seriously hampered. Thus the International Benchmark Exercise (IBE) sponsored by the OECD/NEA have been fundamental to analyze the use of CFD codes in the nuclear industry, because although these codes are mature in many fields, still exist doubts about them in critical aspects of thermohydraulic calculations, even in single-phase scenarios. The Polytechnic University of Valencia (UPV) and the Universitat Jaume I (UJI), sponsored by the Nuclear Safety Council (CSN), have actively participated in all benchmark's proposed by NEA, as in the expert meetings,. In this paper, a summary of participation in the various IBE will be held, describing the benchmark itself, the CFD model created for it, and the main conclusions. (Author)
Vincent Casseau; Rodrigo C. Palharini; Thomas J. Scanlon; Richard E. Brown
2016-01-01
A two-temperature CFD (computational fluid dynamics) solver is a prerequisite to any spacecraft re-entry numerical study that aims at producing results with a satisfactory level of accuracy within realistic timescales. In this respect, a new two-temperature CFD solver, hy2Foam, has been developed within the framework of the open-source CFD platform OpenFOAM for the prediction of hypersonic reacting flows. This solver makes the distinct juncture between the trans-rotational and multiple vibrat...
Validation of a CFD methodology for positive displacement LVAD analysis using PIV data.
Medvitz, Richard B; Reddy, Varun; Deutsch, Steve; Manning, Keefe B; Paterson, Eric G
2009-11-01
Computational fluid dynamics (CFD) is used to asses the hydrodynamic performance of a positive displacement left ventricular assist device. The computational model uses implicit large eddy simulation direct resolution of the chamber compression and modeled valve closure to reproduce the in vitro results. The computations are validated through comparisons with experimental particle image velocimetry (PIV) data. Qualitative comparisons of flow patterns, velocity fields, and wall-shear rates demonstrate a high level of agreement between the computations and experiments. Quantitatively, the PIV and CFD show similar probed velocity histories, closely matching jet velocities and comparable wall-strain rates. Overall, it has been shown that CFD can provide detailed flow field and wall-strain rate data, which is important in evaluating blood pump performance.
CFD simulation of a four-loop PWR at asymmetric operation conditions
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Cheng, Jian-Ping; Yan, Li-Ming; Li, Feng-Chen, E-mail: lifch@hit.edu.cn
2016-04-15
Highlights: • A CFD numerical simulation procedure was established for simulating RPV of VVER-1000. • The established CFD approach was validated by comparing with available data. • Thermal hydraulic characteristics under asymmetric operation condition were investigated. • Apparent influences of the shutdown loop on its neighboring loops were obtained. - Abstract: The pressurized water reactor (PWR) with multiple loops may have abnormal working conditions with coolant pumps out of running in some loops. In this paper, a computational fluid dynamics (CFD) numerical study of the four-loop VVER-1000 PWR pressure vessel model was presented. Numerical simulations of the thermohydrodynamic characteristics in the pressure vessel were carried out at different inlet conditions with four and three loops running, respectively. At normal stead-state condition (four-loop running), different parameters were obtained for the full fluid domain, including pressure losses across different parts, pressure, velocity and temperature distributions in the reactor pressure vessel (RPV) and mass flow distribution of the coolant at the inlet of reactor core. The obtained results for pressure losses matched with the experimental reference values of the VVER-1000 PWR at Tianwan nuclear power plant (NPP). For most fuel assemblies (FAs), the inlet flow rates presented a symmetrical distribution about the center under full-loop operation conditions, which accorded with the practical distribution. These results indicate that it is now possible to study the dynamic transition process between different asymmetric operation conditions in a multi-loop PWR using the established CFD method.
Corley, R A; Minard, K R; Kabilan, S; Einstein, D R; Kuprat, A P; Harkema, J R; Kimbell, J S; Gargas, M L; Kinzell, John H
2009-05-01
The percentages of total airflows over the nasal respiratory and olfactory epithelium of female rabbits were calculated from computational fluid dynamics (CFD) simulations of steady-state inhalation. These airflow calculations, along with nasal airway geometry determinations, are critical parameters for hybrid CFD/physiologically based pharmacokinetic models that describe the nasal dosimetry of water-soluble or reactive gases and vapors in rabbits. CFD simulations were based upon three-dimensional computational meshes derived from magnetic resonance images of three adult female New Zealand White (NZW) rabbits. In the anterior portion of the nose, the maxillary turbinates of rabbits are considerably more complex than comparable regions in rats, mice, monkeys, or humans. This leads to a greater surface area to volume ratio in this region and thus the potential for increased extraction of water soluble or reactive gases and vapors in the anterior portion of the nose compared to many other species. Although there was considerable interanimal variability in the fine structures of the nasal turbinates and airflows in the anterior portions of the nose, there was remarkable consistency between rabbits in the percentage of total inspired airflows that reached the ethmoid turbinate region (approximately 50%) that is presumably lined with olfactory epithelium. These latter results (airflows reaching the ethmoid turbinate region) were higher than previous published estimates for the male F344 rat (19%) and human (7%). These differences in regional airflows can have significant implications in interspecies extrapolations of nasal dosimetry.
Cavicchioli, Gilberto
2008-01-01
A presente dissertação tem por finalidade analisar as relações entre os estilos de liderança e a continuidade do negócio na percepção dos fundadores de empresas familiares do setor de transportes de cargas no Brasil. Pretende-se contribuir no modo de avaliar aspectos da estrutura organizacional das empresas de transporte rodoviário de cargas, as ETCs, no sentido de averiguar como os fundadores ou principais gestores dessas empresas consideram que seus estilos de liderança sinalizam respaldos ...
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Tatiana Cecagno Galvan
2015-09-01
Full Text Available ResumoOs resultados educacionais estão ligados à carga de trabalho do estudante que, por sua vez, sofre influência de fatores individuais e do contexto institucional. Contudo, no âmbito da pós-graduação brasileira, e mais especificamente no caso da Engenharia de Produção, pouco é conhecido sobre a intensidade dessa carga de trabalho, fatores contribuintes e meios de gerenciá-la. Este estudo tem como objetivo realizar uma avaliação exploratória da carga de trabalho em estudantes de Pós-Graduação em Engenharia de Produção. A avaliação foi realizada em um curso nacional de excelência na área, por meio de: entrevistas semiestruturadas com três alunos, aplicação de um questionário (NASA-TLX adaptado respondido por trinta e três alunos; reunião de feedback dos resultados dos questionários aos alunos. Os dados indicaram que a carga de trabalho é alta e similar entre as diferentes modalidades do curso: mestrado profissional, mestrado acadêmico e doutorado. Além disso, foi possível identificar o alto nível de frustração entre alunos do mestrado profissional, o alto nível de esforço no mestrado acadêmico, a grande demanda mental do doutorado, e a maior demanda temporal para quem exerce outras atividades profissionais além dos estudos. Dentre os fatores contribuintes nesta alta carga de trabalho, foi identificada a falta de acompanhamento do orientador, a realização de trabalhos acadêmicos não diretamente ligados ao projeto de pesquisa, a alta exigência imposta pelos estudantes a si mesmos e o medo de não finalizar o trabalho.
CFD study of ejector flow behavior in a blast furnace gas galvanizing plant
Besagni, Giorgio; Mereu, Riccardo; Inzoli, Fabio
2015-02-01
In recent years, there has been a growing interest toward Blast Furnace Gas (BFG) as a low-grade energy source for industrial furnaces. This paper considers the revamping of a galvanic plant furnace converted to BFG from natural gas. In the design of the new system, the ejector on the exhaust line is a critical component. This paper studies the flow behavior of the ejector using a Computational Fluid Dynamics (CFD) analysis. The CFD model is based on a 3D representation of the ejector, using air and exhaust gases as working fluids. This paper is divided in three parts. In the first part, the galvanic plant used as case study is presented and discussed, in the second part the CFD approach is outlined, and in the third part the CFD approach is validated using experimental data and the numerical results are presented and discussed. Different Reynolds-Averaged Navier-Stokes (RANS) turbulence models ( k-ω SST and k-ɛ Realizable) are evaluated in terms of convergence capability and accuracy in predicting the pressure drop along the ejector. Suggestions for future optimization of the system are also provided.
Chung, Bongjae; Cebral, Juan Raul
2015-01-01
Computational fluid dynamics (CFD) has been used for several years to identify mechanical risk factors associated with aneurysmal evolution and rupture as well as to understand flow characteristics before and after surgical treatments in order to help the clinical decision making process. We used the keywords, "CFD" and "aneurysms" to search recent publications since about 2000, and categorized them into (i) studies of rupture risk factors and (ii) investigations of pre- and post-evaluations of surgical treatment with devices like coils and flow diverters (FD). This search enables us to examine the current status of CFD as a clinical tool and to determine if CFD can potentially become an important part of the routine clinical practice for the evaluation and treatment of aneurysms in near future. According to previous reports, it has been argued that CFD has become a quite robust non-invasive tool for the evaluation of surgical devices, especially in the early stages of device design and it has also been applied successfully to the study of rupture risk assessment. However, we find that due to the large number of pre-processing inputs further efforts of validation and reproducibility of CFD with larger clinical datasets are still essential to identify standardized mechanical risk factors. As a result, we identify the following needs to have a robust CFD tool for clinical use: (i) more reliability tests through validation studies, (ii) analyses of larger generalized clinical datasets to find converging universal risk parameters, (iii) fluid structure interaction (FSI) analyses to better understand the detailed vascular remodeling processes associated with aneurysm growth, evolution and rupture, and (iv) better coordinated and organized communications and collaborations between engineers and clinicians.
Aerodynamic optimization of wind turbine rotor using CFD/AD method
Cao, Jiufa; Zhu, Weijun; Wang, Tongguang; Ke, Shitang
2018-05-01
The current work describes a novel technique for wind turbine rotor optimization. The aerodynamic design and optimization of wind turbine rotor can be achieved with different methods, such as the semi-empirical engineering methods and more accurate computational fluid dynamic (CFD) method. The CFD method often provides more detailed aerodynamics features during the design process. However, high computational cost limits the application, especially for rotor optimization purpose. In this paper, a CFD-based actuator disc (AD) model is used to represent turbulent flow over a wind turbine rotor. The rotor is modeled as a permeable disc of equivalent area where the forces from the blades are distributed on the circular disc. The AD model is coupled with a Reynolds Averaged Navier-Stokes (RANS) solver such that the thrust and power are simulated. The design variables are the shape parameters comprising the chord, the twist and the relative thickness of the wind turbine rotor blade. The comparative aerodynamic performance is analyzed between the original and optimized reference wind turbine rotor. The results showed that the optimization framework can be effectively and accurately utilized in enhancing the aerodynamic performance of the wind turbine rotor.
A Predictive Framework to Elucidate Venous Stenosis: CFD & Shape Optimization.
Javid Mahmoudzadeh Akherat, S M; Cassel, Kevin; Boghosian, Michael; Hammes, Mary; Coe, Fredric
2017-07-01
The surgical creation of vascular accesses for renal failure patients provides an abnormally high flow rate conduit in the patient's upper arm vasculature that facilitates the hemodialysis treatment. These vascular accesses, however, are very often associated with complications that lead to access failure and thrombotic incidents, mainly due to excessive neointimal hyperplasia (NH) and subsequently stenosis. Development of a framework to monitor and predict the evolution of the venous system post access creation can greatly contribute to maintaining access patency. Computational fluid dynamics (CFD) has been exploited to inspect the non-homeostatic wall shear stress (WSS) distribution that is speculated to trigger NH in the patient cohort under investigation. Thereafter, CFD in liaison with a gradient-free shape optimization method has been employed to analyze the deformation modes of the venous system enduring non-physiological hemodynamics. It is observed that the optimally evolved shapes and their corresponding hemodynamics strive to restore the homeostatic state of the venous system to a normal, pre-surgery condition. It is concluded that a CFD-shape optimization coupling that seeks to regulate the WSS back to a well-defined physiological WSS target range can accurately predict the mode of patient-specific access failure.
CFD voor een gezonde en comfortabele stedelijke omgeving
Blocken, B.J.E.
2010-01-01
Stedebouwfysica omvat de studie van fysische processen om te zorgen voor een gezonde, comfortabele en duurzame stedelijke omgeving. Dit artikel bespreekt kort de belangrijke rol die CFD-simulaties hierin kunnen spelen, op voorwaarde dat hun nauwkeurigheid en betrouwbaarheid gegarandeerd zijn. Het
Considering value of information when using CFD in design
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Misra, John Satprim [Iowa State Univ., Ames, IA (United States)
2009-01-01
This thesis presents an approach to find lower resolution CFD models that can accurately lead a designer to a correct decision at a lower computational cost. High-fidelity CFD models often contain too much information and come at a higher computational cost, limiting the designs a designer can test and how much optimization can be performed on the design. Lower model resolution is commonly used to reduce computational time. However there are no clear guidelines on how much model accuracy is required. Instead experience and intuition are used to select an appropriate lower resolution model. This thesis presents an alternative to this ad hoc method by considering the added value of the addition information provided by increasing accurate and more computationally expensive models.
GENERALIZATION OF ZAD STRATEGY: AN APPLICATION TO A DC-DC BUCK CONVERTER
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FABIOLA ANGULO GARCIA
2011-01-01
Full Text Available En la última década se ha reportado la estrategia de control Zero Average Dynamics (ZAD como una alternativa al control de los convertidores de potencia, garantizando frecuencia fi ja de conmutación y bajo error. Sin embargo la estabilidad del sistema depende fuertemente de la carga, por lo cual no es robusto. Cuando se pierde la estabilidad la frecuencia fi ja de conmutación se pierde también. En este artículo se presenta la generalización de la técnica ZAD dentro del marco de la teoría de probabilidades. Usando este marco es posible recuperar el ZAD tal como ha sido analizado hasta ahora y se pueden generar nuevas estrategias de control, las cuales son más estables que las usadas en el ZAD. Por este motivo a esta técnica se le ha llamado Generalized Zero Average Dynamics (GZAD. Presentamos algunas simulaciones del GZAD aplicado a un convertidor de potencia reductor. Esta nueva estrategia no puede ser obtenida con el ZAD clásico. Las simulaciones numéricas muestran buen desempeño del controlador con bajo error de regulación y robustez ante cambio en la carga.
Operational Augmentation of Forced Circulation Type Solar Dryer System Using CFD Analysis
Atul Patel; Gaurav Patel
2014-01-01
Solar drying is basically heat and mass transfer process in which the liquid water from the surface and the vapour removed by draft. The efficiency of a solar drying system is affected by the properties of drying materials.e.g. size, shape and geometry as well as ambient conditions. In this research article, the authors have done the CFD analysis of a Forced Circulation type Solar Dryer used conventionally for dehydrating vegetables and fruits. Using CFD analysis, the limiting...
"Análise da carga mecânica no joeho durante o agachamento"
Rogério Pessoto Hirata
2006-01-01
Existe um conceito difundido entre professores de educação física, fisioterapeutas e ortopedistas que o joelho não deve ser demasiadamente anteriorizado em relação à ponta do pé na direção ântero-posterior durante qualquer tipo de agachamento de modo a diminuir a carga mecânica imposta ao joelho. No entanto, são escassas as evidências quantitativas que corroboram este conceito. Este trabalho tem como objetivo estimar forças e torque na articulação do joelho em indivíduos saudáveis durante o e...
Modelo analítico de resistência ao rolamento de pneus de carga
Marcos Rodolfo Gali
2015-01-01
Resumo: Em 2012, Rhyne & Cron desenvolveram um modelo analítico para estimar a mínima Resistência ao Rolamento (RR) para pneus destinados aos veículos de passageiro. Os parâmetros estudados pelos autores foram a área de contato, a espessura e a largura da rodagem, o raio da cintura metálica, o módulo elástico do composto da banda de rodagem, a carga vertical imposta, a pressão de inflação do pneu e a área efetiva de contato do pneu com o solo. Para o fator área de contato, os autores simplifi...
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Breno Tostes de Gomes Garcia
2017-04-01
Full Text Available A partir da Política Nacional de Resíduos Sólidos, o setor portuário brasileiro foi obrigado a gerenciar os resíduos sólidos gerados nos portos e terminais portuários. A partir disto, o levantamento do inventário dos resíduos, da carga movimentada e da quantidade de atracações possibilitou analisar a eficiência na geração dos resíduos sólidos dos terminais portuários cuja natureza da carga selecionada foi a carga geral. Para isto, utilizou o modelo DEA BCC, por considerar retornos variáveis de escala, orientado a output. O resultado evidenciou que a DMU mais eficiente foi a que menos gerou resíduos sólidos da amostra, entretanto, uma DMU não apresentou o maior valor para a eficiência padrão, mas apresentou valor máximo na composta, gerando uma inconsistência nos resultados. Apesar disto, o modelo permitiu analisar as referências das DMU’s ineficientes, onde é possível ter mais de uma DMU eficiente como referência para se tornarem eficientes.
MPI to Coarray Fortran: Experiences with a CFD Solver for Unstructured Meshes
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Anuj Sharma
2017-01-01
Full Text Available High-resolution numerical methods and unstructured meshes are required in many applications of Computational Fluid Dynamics (CFD. These methods are quite computationally expensive and hence benefit from being parallelized. Message Passing Interface (MPI has been utilized traditionally as a parallelization strategy. However, the inherent complexity of MPI contributes further to the existing complexity of the CFD scientific codes. The Partitioned Global Address Space (PGAS parallelization paradigm was introduced in an attempt to improve the clarity of the parallel implementation. We present our experiences of converting an unstructured high-resolution compressible Navier-Stokes CFD solver from MPI to PGAS Coarray Fortran. We present the challenges, methodology, and performance measurements of our approach using Coarray Fortran. With the Cray compiler, we observe Coarray Fortran as a viable alternative to MPI. We are hopeful that Intel and open-source implementations could be utilized in the future.
Aerodynamic study of time-trial helmets in cycling racing using CFD analysis.
Beaumont, F; Taiar, R; Polidori, G; Trenchard, H; Grappe, F
2018-01-23
The aerodynamic drag of three different time-trial cycling helmets was analyzed numerically for two different cyclist head positions. Computational Fluid Dynamics (CFD) methods were used to investigate the detailed airflow patterns around the cyclist for a constant velocity of 15 m/s without wind. The CFD simulations have focused on the aerodynamic drag effects in terms of wall shear stress maps and pressure coefficient distributions on the cyclist/helmet system. For a given head position, the helmet shape, by itself, obtained a weak effect on a cyclist's aerodynamic performance (CFD results have also shown that both helmet shape and head position significantly influence drag forces, pressure and wall shear stress distributions on the whole cyclist's body due to the change in the near-wake behavior and in location of corresponding separation and attachment areas around the cyclist. Copyright © 2017 Elsevier Ltd. All rights reserved.
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Larissa Bertacchini de Oliveira
2015-12-01
Full Text Available RESUMO Objetivo Identificar os fatores associados à carga de trabalho de enfermagem no cuidado a pacientes no pós-operatório de cirurgia cardíaca. Método Estudo de coorte prospectivo, conduzido com 187 pacientes da Unidade de Terapia Intensiva Cirúrgica (UTI do Instituto do Coração. Os dados foram coletados nas primeiras 24 e 72 horas do paciente na UTI. A variável dependente foi a carga de trabalho calculada por meio do Nursing Activities Score (NAS e as independentes foram de natureza demográfico-clínicas e escores de morbimortalidade. Para análise dos dados utilizou-se os testes de Wilcoxon-Mann-Whitney e de correlação de Spearman, e a regressão linear com modelo de efeitos mistos. Resultados A maioria dos pacientes era do sexo masculino (59,4%, com média de idade de 61 anos (±12,7 e 43,9% desenvolveram algum tipo de complicação no pós-operatório. Nas 24 horas, a carga de trabalho foi de 82,4% (±3,4 e foi de 58,1% (±3,4 nas 72 horas. Os fatores associados ao aumento do NAS foram: tempo de internação do paciente na UTI (p=0,036 e a presença de complicações (p<0,001. Conclusão A gravidade do paciente nas 24 horas, em oposição a inúmeros estudos, não influenciou no aumento da carga de trabalho, a qual se mostrou associada ao tempo de internação e às complicações.
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María I Montti
2013-01-01
Full Text Available En Argentina, la producción cítrica es muy importante. Para el control de enfermedades y plagas en las quintas y empaques son utilizados diferentes pesticidas. Los objetivos de este estudio fueron: optimizar diferentes metodologías analíticas para la determi- nación de residuos de pesticidas en fruta y aceite esencial, y determinar el efecto de la carga inicial sobre los aceites esenciales obtenidos durante el proceso industrial. La calibración se llevó a cabo con matriz adicionada debido al efecto matriz. Los mé- todos propuestos fueron selectivos, precisos, exactos y sensibles. La concentración de residuos encontrados en fruta fresca varió dependiendo del lote y pesticida. La persistencia en fruta postlavada, aceite pulido y descerado fue distinta para cada analito. Se observó una ligera reducción de los residuos en el aceite descerado debido probablemente a la partición de los mismos en la fase cerosa. Los resultados muestran que la carga inicial en la fruta es significante.
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Alfredo L. Coello-Velázquez
2015-07-01
Full Text Available Con el propósito de disminuir los errores (residuos que tienen lugar en la determinación de la carga circulante en los circuitos cerrados de molienda o trituración, aplicando los métodos de los mínimos cuadrados y de los multiplicadores de Lagrange a las ecuaciones de balance, se desarrolla un procedimiento que minimiza las desviaciones e incongruencias en el balance de distribución de las clases granulométricas de los productos del esquema. Tomando como punto de partida los datos experimentales obtenidos por Coello (1993, se realiza la validación del procedimiento propuesto. Los resultados muestran que el procedimiento aplicado, permite el mejor ajuste cálculo de la carga circulante y a partir de sus valores, se recalculan los contenidos de las clases granulométricas de los productos del esquema que eliminan las incongruencias y errores de la distribución del contenido de las clases granulométricas generados en la toma y procesamiento general de las muestras.
A novel methodology for interpreting air quality measurements from urban streets using CFD modelling
Solazzo, Efisio; Vardoulakis, Sotiris; Cai, Xiaoming
2011-09-01
In this study, a novel computational fluid dynamics (CFD) based methodology has been developed to interpret long-term averaged measurements of pollutant concentrations collected at roadside locations. The methodology is applied to the analysis of pollutant dispersion in Stratford Road (SR), a busy street canyon in Birmingham (UK), where a one-year sampling campaign was carried out between August 2005 and July 2006. Firstly, a number of dispersion scenarios are defined by combining sets of synoptic wind velocity and direction. Assuming neutral atmospheric stability, CFD simulations are conducted for all the scenarios, by applying the standard k-ɛ turbulence model, with the aim of creating a database of normalised pollutant concentrations at specific locations within the street. Modelled concentration for all wind scenarios were compared with hourly observed NO x data. In order to compare with long-term averaged measurements, a weighted average of the CFD-calculated concentration fields was derived, with the weighting coefficients being proportional to the frequency of each scenario observed during the examined period (either monthly or annually). In summary the methodology consists of (i) identifying the main dispersion scenarios for the street based on wind speed and directions data, (ii) creating a database of CFD-calculated concentration fields for the identified dispersion scenarios, and (iii) combining the CFD results based on the frequency of occurrence of each dispersion scenario during the examined period. The methodology has been applied to calculate monthly and annually averaged benzene concentration at several locations within the street canyon so that a direct comparison with observations could be made. The results of this study indicate that, within the simplifying assumption of non-buoyant flow, CFD modelling can aid understanding of long-term air quality measurements, and help assessing the representativeness of monitoring locations for population
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Munoz-cobo, J. L.; Chiva, S.; Pena, C.; Vela, E.
2014-07-01
In this work the development of a methodology is studied to evaluate the uncertainty in the results of CFD codes and is compatible with the VV-20 standard Standard for Verification and Validation in CFD and Heat Transfer {sup ,} developed by the Association of Mechanical Engineers ASME . Similarly, the alternatives are studied for obtaining existing uncertainty in the results to see which is the best choice from the point of view of implementation and time. We have developed two methods for calculating uncertainty of the results of a CFD code, the first method based on the use of techniques of Monte-Carlo for the propagation of uncertainty in this first method we think it is preferable to use the statistics of the order to determine the number of cases to execute the code, because this way we can always determine the confidence interval desired level of output quantities. The second type of method we have developed is based on non-intrusive polynomial chaos. (Author)
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Romero Aguilar, Mariana [Centro de Investigacion en Biotecnologia, Universidad Autonoma del Estado de Morelos, Cuernavaca, Morelos (Mexico)]. E-mail: ortizhl@uaem.mx; Colin Cruz, Arturo [Facultad de Quimica, Universidad Autonoma del Estado de Mexico, Toluca, Estado de Mexico (Mexico); Sanchez Salinas, Enrique; Ortiz Hernandez, Ma. Laura [Centro de Investigacion en Biotecnologia, Universidad Autonoma del Estado de Morelos, Cuernavaca, Morelos (Mexico)
2009-08-15
tratamiento, lo cual crea la necesidad de desarrollar tecnologias para su depuracion. Los humedales artificiales son una alternativa de tratamiento debido a su alta eficiencia de remocion de contaminantes y a su bajo costo de instalacion y mantenimiento. En el presente trabajo se evalua el porcentaje de remocion de la carga organica de aguas residuales, en un sistema de tratamiento por humedales artificiales de flujo horizontal y con dos especies vegetales. El sistema fue disenado con tres modulos instalados de manera secuencial. En el primero se integraron organismos de la especie Phragmites australis (Cav.) Trin. ex Steudel, en el segundo, organismos de la especie Typha dominguensis (Pers.) Steudel y en el tercero las dos especies. Los modulos experimentales fueron instalados a la salida de un tratamiento primario, el cual contiene aguas residuales municipales provenientes de un edificio de investigacion. En el agua se analizaron los siguientes parametros: demanda quimica de oxigeno (DQO), los iones de nitrogeno (N-NO{sub 3}{sup -}, N-NO{sub 2}{sup -} y N-NH4+) y el fosforo total. Tambien se realizo el conteo de bacterias asociadas al sistema. Los resultados demostraron que el sistema es una opcion para la remocion de la carga organica y de nutrimentos, de bajo costo de operacion y mantenimiento.
Materiales, tecnologías y prototipos de viviendas de muy bajo coste
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Salas Serrano, Julián
1982-11-01
Full Text Available Not available.El fin último de la investigación es el de conseguir unas tipologías de viviendas realizadas mediante materiales, procedimientos o sistemas constructivos que permitan proporcionar un producto final, cuyas características fundamentales sean: adecuación a las necesidades físicas y socioculturales de la zona y, prioritariamente, la consecución de un muy bajo coste da ejecución de las mismas. Cuando se habla a continuación de «viviendas de muy bajo coste» se debe entender que nos referimos a las que cumplen básicamente las dos condiciones limitativas aceptadas por las Naciones Unidas (UNCHSHABITAT: a Superficie construida comprendida entre 30 y 50 m2. b Coste de construcción inferior a los 100 $ USA (1982 por metro cuadrado construido. (Para nuestras condiciones, fijaríamos un coste aproximado de 10.000 pts/m2.
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Mazda Biglari
2016-06-01
Full Text Available Two modeling approaches, the scaling-law and CFD (Computational Fluid Dynamics approaches, are presented in this paper. To save on experimental cost of the pilot plant, the scaling-law approach as a low-computational-cost method was adopted and a small scale column operating under ambient temperature and pressure was built. A series of laboratory tests and computer simulations were carried out to evaluate the hydrodynamic characteristics of a pilot fluidized-bed biomass gasifier. In the small scale column solids were fluidized. The pressure and other hydrodynamic properties were monitored for the validation of the scaling-law application. In addition to the scaling-law modeling method, the CFD approach was presented to simulate the gas-particle system in the small column. 2D CFD models were developed to simulate the hydrodynamic regime. The simulation results were validated with the experimental data from the small column. It was proved that the CFD model was able to accurately predict the hydrodynamics of the small column. The outcomes of this research present both the scaling law with the lower computational cost and the CFD modeling as a more robust method to suit various needs for the design of fluidized-bed gasifiers.
Direct CFD Predictions of Low Frequency Sounds Generated by a Helicopter Main Rotor
Sim, Ben W.; Potsdam, Mark A.; Conner, Dave A.; Conner, Dave A.; Watts, Michael E.
2010-01-01
The use of CFD to directly predict helicopter main rotor noise is shown to be quite promising as an alternative mean for low frequency source noise evaluation. Results using existing state-of-the-art grid structures and finite-difference schemes demonstrated that small perturbation pressures, associated with acoustics radiation, can be extracted with some degree of fidelity. Accuracy of the predictions are demonstrated via comparing to predictions from conventional acoustic analogy-based models, and with measurements obtained from wind tunnel and flight tests for the MD-902 helicopter at several operating conditions. Findings show that the direct CFD approach is quite successfully in yielding low frequency results due to thickness and steady loading noise mechanisms. Mid-to-high frequency contents, due to blade-vortex interactions, are not predicted due to CFD modeling and grid constraints.
RANS based CFD methodology for a real scale 217-pin wire-wrapped fuel assembly of KAERI PGSFR
Energy Technology Data Exchange (ETDEWEB)
Jeong, Jae-Ho, E-mail: jhjeong@kaeri.re.kr [Korea Atomic Energy Research Institute, 989-111 Daedeok-daero, Yuseoung-gu, Daejeon (Korea, Republic of); Song, Min-Seop [Department of Nuclear Engineering, Seoul National University, 559 Gwanak-ro, Gwanak-gu, Seoul (Korea, Republic of); Lee, Kwi-Lim [Korea Atomic Energy Research Institute, 989-111 Daedeok-daero, Yuseoung-gu, Daejeon (Korea, Republic of)
2017-03-15
Highlights: • This paper presents a suitable way for a practical RANS based CFD methodology which is applicable to real scale 217-pin wire-wrapped fuel assembly of KAERI PGSFR. • A key point of differentiation of the RANS based CFD methodology in this study is adapting an innovative grid generation method using a fortran based in-house code with a GGI function in a general-purpose commercial CFD code, CFX. • The RANS based CFD methodology is implemented with high resolution scheme and SST turbulence model in the 7-pin 37-pin, and 127-pin wire-wrapped fuel assembly of PNC and JNC. Furthermore, the RANS based CFD methodology can be successfully extended to the real scale 217-pin wire-wrapped fuel bundles of KAERI PGSFR. • Three-dimensional thermal-hydraulic characteristics have been also investigated briefly. - Abstract: This paper presents a suitable way for a practical RANS (Reynolds Averaged Navier-Stokes simulation) based CFD (Computational Fluid Dynamics) methodology which is applicable to real scale 217-pin wire-wrapped fuel assembly of KAERI (Korea Atomic Energy Research Institute) PGSFR (Prototype Gen-IV Sodium-cooled Fast Reactor). The main purpose of the current study is to support license issue for the KAERI PGSFR core safety and to elucidate thermal-hydraulic characteristics in a 217-pin wire-wrapped fuel assembly of KAERI PGSFR. A key point of differentiation of the RANS based CFD methodology in this study is adapting an innovative grid generation method using a fortran based in-house code with a GGI (General Grid Interface) function in a general-purpose commercial CFD code, CFX. The innovative grid generation method with GGI function can achieve to simulate a real wire shape with minimizing cell skewness. The RANS based CFD methodology is implemented with high resolution scheme in convection term and SST (Shear Stress Transport) turbulence model in the 7-pin 37-pin, and 127-pin wire-wrapped fuel assembly of PNC (Power reactor and Nuclear fuel
Directory of Open Access Journals (Sweden)
Mota, Eduardo Gonçalves
2011-01-01
Conclusão: A resina Z2 teve a maior resistência à compressão; Z2 e TC apresentaram maiores módulo de elasticidade, VHN e conteúdo de carga em peso. O conteúdo de carga em peso teve uma forte influência nas propriedades mecânicas avaliadas (0,78
DESARROLLO E IMPLEMENTACIÓN DE FOTOCONTROL TEMPORIZADO CON TECNOLOGÍA DE BAJO CONSUMO
Directory of Open Access Journals (Sweden)
Fredy Hernán Martínez Sarmiento
2013-09-01
Full Text Available En este trabajo se presenta el desarrollo e implementación de un fotocontrol con tecnología de bajo consumo desarrollado con un microcontrolador, el cual controla variables de tensión, luminosidad y sincronización con la red, por medio de una salida con modo PWM producir una salida de Vdc en el relé. El microcontrolador realiza un muestreo análogo de voltaje sobre la onda sinusoidal y se hace un filtro de promedio móvil para eliminar ruido de la onda.La temporización se realiza cuando el contacto del relé está cerrado y el tiempo a temporizar es programado por el usuario el cual lo requiera, el fotocontrol presenta un modo de ultra bajo consumo en el microcontrolador con un supercap.
Energy Technology Data Exchange (ETDEWEB)
Bueno, B.; Cejudo, J.; Carrillo, A.
2008-07-01
Computational fluid dynamics (CFD) application to building energy simulation (STE) allows better modelling of indoor air performance and therefore it can be used to optimize the design of natural ventilation systems. In this paper, a natural ventilation system based on thermal chimney applied to a residential building is analyzed. Energy Plus simulations are applied to an apartment and results are coupled to CFD simulations to determine ventilation rates and study convection in the space. CFD simulations are also applied to evaluate indoor air distribution and study how ventilation rate is affected by the pressure drop at ventilation grilles. (Author)
Blood flow quantification using 1D CFD parameter identification
Brosig, Richard; Kowarschik, Markus; Maday, Peter; Katouzian, Amin; Demirci, Stefanie; Navab, Nassir
2014-03-01
Patient-specific measurements of cerebral blood flow provide valuable diagnostic information concerning cerebrovascular diseases rather than visually driven qualitative evaluation. In this paper, we present a quantitative method to estimate blood flow parameters with high temporal resolution from digital subtraction angiography (DSA) image sequences. Using a 3D DSA dataset and a 2D+t DSA sequence, the proposed algorithm employs a 1D Computational Fluid Dynamics (CFD) model for estimation of time-dependent flow values along a cerebral vessel, combined with an additional Advection Diffusion Equation (ADE) for contrast agent propagation. The CFD system, followed by the ADE, is solved with a finite volume approximation, which ensures the conservation of mass. Instead of defining a new imaging protocol to obtain relevant data, our cost function optimizes the bolus arrival time (BAT) of the contrast agent in 2D+t DSA sequences. The visual determination of BAT is common clinical practice and can be easily derived from and be compared to values, generated by a 1D-CFD simulation. Using this strategy, we ensure that our proposed method fits best to clinical practice and does not require any changes to the medical work flow. Synthetic experiments show that the recovered flow estimates match the ground truth values with less than 12% error in the mean flow rates.
CFD analysis of hypersonic, chemically reacting flow fields
Edwards, T. A.
1993-01-01
Design studies are underway for a variety of hypersonic flight vehicles. The National Aero-Space Plane will provide a reusable, single-stage-to-orbit capability for routine access to low earth orbit. Flight-capable satellites will dip into the atmosphere to maneuver to new orbits, while planetary probes will decelerate at their destination by atmospheric aerobraking. To supplement limited experimental capabilities in the hypersonic regime, computational fluid dynamics (CFD) is being used to analyze the flow about these configurations. The governing equations include fluid dynamic as well as chemical species equations, which are being solved with new, robust numerical algorithms. Examples of CFD applications to hypersonic vehicles suggest an important role this technology will play in the development of future aerospace systems. The computational resources needed to obtain solutions are large, but solution adaptive grids, convergence acceleration, and parallel processing may make run times manageable.
Pneumafil casing blower through moving reference frame (MRF) - A CFD simulation
Manivel, R.; Vijayanandh, R.; Babin, T.; Sriram, G.
2018-05-01
In this analysis work, the ring frame of Pneumafil casing blower of the textile mills with a power rating of 5 kW have been simulated using Computational Fluid Dynamics (CFD) code. The CFD analysis of the blower is carried out in Ansys Workbench 16.2 with Fluent using MRF solver settings. The simulation settings and boundary conditions are based on literature study and field data acquired. The main objective of this work is to reduce the energy consumption of the blower. The flow analysis indicated that the power consumption is influenced by the deflector plate orientation and deflector plate strip situated at the outlet casing of the blower. The energy losses occurred in the blower is due to the recirculation zones formed around the deflector plate strip. The deflector plate orientation is changed and optimized to reduce the energy consumption. The proposed optimized model is based on the simulation results which had relatively lesser power consumption than the existing and other cases. The energy losses in the Pneumafil casing blower are reduced through CFD analysis.
Temperature Simulation of Greenhouse with CFD Methods and Optimal Sensor Placement
Directory of Open Access Journals (Sweden)
Yanzheng Liu
2014-03-01
Full Text Available The accuracy of information monitoring is significant to increase the effect of Greenhouse Environment Control. In this paper, by taking simulation for the temperature field in the greenhouse as an example, the CFD (Computational Fluid Dynamics simulation model for measuring the microclimate environment of greenhouse with the principle of thermal environment formation was established, and the temperature distributions under the condition of mechanical ventilation was also simulated. The results showed that the CFD model and its solution simulated for greenhouse thermal environment could describe the changing process of temperature environment within the greenhouse; the most suitable turbulent simulation model was the standard k?? model. Under the condition of mechanical ventilation, the average deviation between the simulated value and the measured value was 0.6, which was 4.5 percent of the measured value. The distribution of temperature filed had obvious layering structures, and the temperature in the greenhouse model decreased gradually from the periphery to the center. Based on these results, the sensor number and the optimal sensor placement were determined with CFD simulation method.
Energy Technology Data Exchange (ETDEWEB)
Hoyes, J.R., E-mail: james.hoyes@hsl.gsi.gov.uk; Ivings, M.J.
2016-12-15
Highlights: • The ability of CFD to predict hydrogen stratification phenomena is investigated. • Contrary to expectation, simulations on tetrahedral meshes under-predict mixing. • Simulations on structured meshes give good agreement with experimental data. • CFD model used to investigate the effects of stratification on PAR performance. • Results show stratification can have a significant effect on PAR performance. - Abstract: Computational Fluid Dynamics (CFD) models are maturing into useful tools for supporting safety analyses. This paper investigates the capabilities of CFD models for predicting hydrogen stratification in a containment vessel using data from the NEA/OECD SETH2 MISTRA experiments. Further simulations are then carried out to illustrate the qualitative effects of hydrogen stratification on the performance of Passive Autocatalytic Recombiner (PAR) units. The MISTRA experiments have well-defined initial and boundary conditions which makes them well suited for use in a validation study. Results are presented for the sensitivity to mesh resolution and mesh type. Whilst the predictions are shown to be largely insensitive to the mesh resolution they are surprisingly sensitive to the mesh type. In particular, tetrahedral meshes are found to induce small unphysical convection currents that result in molecular diffusion and turbulent mixing being under-predicted. This behaviour is not unique to the CFD model used here (ANSYS CFX) and furthermore, it may affect simulations run on other non-aligned meshes (meshes that are not aligned perpendicular to gravity), including non-aligned structured meshes. Following existing best practice guidelines can help to identify potential unphysical predictions, but as an additional precaution consideration should be given to using gravity-aligned meshes for modelling stratified flows. CFD simulations of hydrogen recombination in the Becker Technologies THAI facility are presented with high and low PAR positions
Estructuras hexaquirales con coeficiente de Poisson negativo bajo carga uniaxial en el plano
Oscar Gerardo Castro Ardila; Gonzalo Fernando Casanova García; Yesid Aguilar Castro
2012-01-01
El estudio y las aplicaciones de estructuras deformables con formas celulares y relación de Poisson efectiva negativa son de interés en la actualidad para los sectores automotriz y aeroespacial, como también para la aplicación en componentes ópticos, biológicos, micro electrónicos, estructurales y termo mecánicos. Estas estructuras poseen baja densidad, alta rigidez a cortante en el plano y la capacidad de sufrir grandes deformaciones en el rango elástico del material constitutivo, comparada ...
CFD analysis for road vehicles - case study
Directory of Open Access Journals (Sweden)
Eugen Mihai NEGRUS
2011-09-01
Full Text Available This is a case study on the influence of the lower part of road vehicles on the global drag characteristics. Reducing overall drag by redesigning the lower part of the road vehicles has a potential of almost 20% in the overall drag breakdown, mainly due to the viscous effects and the fluidic interaction of the flow under the car with the typical bluff body flow pattern behind the vehicle. A special parameterization is proposed for the global shape of the sedan car, with respect to the lower part of the body, taking into account most of the specificities of the system. For such a complex interaction, CFD analysis is probably the only efficient tool in order to assess specific design parameterization of a generic car shape. Building on the credibility of such instruments is one of the major goals of this paper. Also, with respect to a target sedan car configuration, examples of successful design strategies are presented. Based on the CFD results, possible strategies to be used in order to reduce viscous drag and global drag characteristics are proposed.
From Spintronics to CFD/ContractForDifferences
Maksoed, W. H.
2015-11-01
Involve the CFD/Computational Fluid Dynamics & HCCI/Homogeneous Charge Compression Ignition - Marcine Frackowiak, dissertation, 2009, for CFD/Contract For Differences accompanied by ``One Man's Crusade to Exonerate Hydrogen for Hindenburg Disaster'' of Addison BAIN, APS News, v. 9, n.7 (July 2000) concludes ``ignition of the blaze'' are responsible to those May, 1937 Accidents. Spintronics their selves include active control & manipulation of spin degree of freedom ever denotes: the nano-obelisk of scanning electron microscopy of galliumnitride/GaN nanostructures-Yong-Hon Cho et al.:``Novel Photonic Device using core-shell nanostructures'', SPIE-newsroom,10.1117/2.1201503.005864. Herewith commercial activated carbon/C can be imaged directly using abberation-corrected transmission electron microscopy[PJF Harris et al.: ``Imaging the Atomic Structures of activated C'', J. Phys. Condens. Matt, 20 (2008) in fig b & c- images networks of hexagonal rings can be clearly be seen depicts equal etchings of 340 px Akhenaten, Nefertiti & their childrens. Incredible acknowledgments to Minister of Education & Culture RI 1998-1999 HE. Mr. Prof. Ir. WIRANTO ARISMUNANDAR, MSME.
Survey of CFD studies on automotive buffeting
International Nuclear Information System (INIS)
An, C.-F.
2005-01-01
In the current automobile market buffeting is one of the customer frequent complaints on luxury cars and SUVs. Buffeting is a low frequency but high level wind noise and makes people inside the vehicle uncomfortable if it lasts for a long period of time. The physical mechanism of buffeting is a complicated phenomenon of aeroacoustic resonance. The aeroacoustic characteristics of buffeting depend on vehicle features and operating conditions. In this paper, a survey of CFD studies on the automotive buffeting is presented. Firstly, several buffeting related concepts, such as Helmholtz resonator, flow over a cavity, shear layer instability and vortex shedding, are reviewed and relevant references are listed. Then, a historic survey of the buffeting investigation is made with emphasis on computational studies. As an example, the buffeting studies at DaimlerChrysler are selected to demonstrate the procedure of CFD simulation for automotive buffeting. The procedure is then validated by the correlation with wind tunnel testing. After that the validated procedure is applied to find solutions for buffeting reduction. Finally, some comments on buffeting studies are addressed. (author)
International Nuclear Information System (INIS)
Wu, Dazhuan; Li, Shiyang; Wu, Peng
2015-01-01
Highlights: • Direct CFD method for flow-pressure characteristic of a pressure control valve. • Fitted and interpreted the constants of the spool hydraulic force equation. • Established a flow coefficient function of both valve opening and pressure drop. • Developed an indirect CFD method based on the valve-governing equations. - Abstract: This study aims to elaborate on specific computational fluid dynamics (CFD) simulation methods for fitting the flow-pressure curve of a pressure control valve, which is spring-load valve widely used in the automotive fuel supply system. Given that the couple mechanism exists between the flow field in the valve and the spring system, numerous researchers chose to fit the characteristic curve with experimental approaches but scarcely focused on CFD methods. A direct CFD method is introduced in this study to solve this problem. Two evaluation criteria are used to determine whether the internal flow is physically real. An experiment is conducted to verify the simulation results, and the accuracy of this CFD method is proved. However, it is designed to solve one operating condition with fixed spring parameters and the accuracy depends on the amount of operating conditions. Thus, an indirect CFD method is developed based on the well-elaborated valve-governing equations to improve the efficiency and broaden the application extension. This method aims to simulate the exact value of the equation constants to uncouple the flow by numerical method. It is capable of dealing with changed operating conditions and varied spring parameters, and the results are also verified. The visualization of the internal flow provides a better understanding of the flow fields in the valve. The valve gap directly influences the hydraulic force distribution on the spool and causes most pressure loss. The physical meaning of the function constants are explained based on the flow analysis
CFD analysis of linear compressors considering load conditions
Bae, Sanghyun; Oh, Wonsik
2017-08-01
This paper is a study on computational fluid dynamics (CFD) analysis of linear compressor considering load conditions. In the conventional CFD analysis of the linear compressor, the load condition was not considered in the behaviour of the piston. In some papers, behaviour of piston is assumed as sinusoidal motion provided by user defined function (UDF). In the reciprocating type compressor, the stroke of the piston is restrained by the rod, while the stroke of the linear compressor is not restrained, and the stroke changes depending on the load condition. The greater the pressure difference between the discharge refrigerant and the suction refrigerant, the more the centre point of the stroke is pushed backward. And the behaviour of the piston is not a complete sine wave. For this reason, when the load condition changes in the CFD analysis of the linear compressor, it may happen that the ANSYS code is changed or unfortunately the modelling is changed. In addition, a separate analysis or calculation is required to find a stroke that meets the load condition, which may contain errors. In this study, the coupled mechanical equations and electrical equations are solved using the UDF, and the behaviour of the piston is solved considering the pressure difference across the piston. Using the above method, the stroke of the piston with respect to the motor specification of the analytical model can be calculated according to the input voltage, and the piston behaviour can be realized considering the thrust amount due to the pressure difference.
Hydraulics and heat transfer in the IFMIF liquid lithium target: CFD calculations
Peña, A.; Esteban, G.A.; Sancho, J.; Kolesnik, V.; Abánades Velasco, Alberto
2009-01-01
CFD (Computational fluid dynamics) calculation turns out to be a good approximation to the real behavior of the lithium (Li) flow of the target of the international fusion materials irradiation facility (IFMIF). A three-dimensional (3D) modelling of the IFMIF design Li target assembly, made with the CFD commercial code ANSYS-FLUENT has been carried out. The simulation by a structural mesh is focused on the thermal-hydraulic analysis inside the Li jet flow. For, this purpose, the two deuteron ...
Passos, Ricardo Gomes; von Sperling, Marcos; Ribeiro, Thiago Bressani
2014-01-01
Knowledge of the hydraulic behaviour is very important in the characterization of a stabilization pond, since pond hydrodynamics plays a fundamental role in treatment efficiency. An advanced hydrodynamics characterization may be achieved by carrying out measurements with tracers, dyes and drogues or using mathematical simulation employing computational fluid dynamics (CFD). The current study involved experimental determinations and mathematical simulations of a full-scale facultative pond in Brazil. A 3D CFD model showed major flow lines, degree of dispersion, dead zones and short circuit regions in the pond. Drogue tracking, wind measurements and dye dispersion were also used in order to obtain information about the actual flow in the pond and as a means of assessing the performance of the CFD model. The drogue, designed and built as part of this research, and which included a geographical positioning system (GPS), presented very satisfactory results. The CFD modelling has proven to be very useful in the evaluation of the hydrodynamic conditions of the facultative pond. A virtual tracer test allowed an estimation of the real mean hydraulic retention time and mixing conditions in the pond. The computational model in CFD corresponded well to what was verified in the field.
Directory of Open Access Journals (Sweden)
Oscarlina Lúcia dos Santos Weber
2005-01-01
Full Text Available O conhecimento das cargas elétricas, permanente e variável, é fundamental para a compreensão e previsão do destino de elementos químicos no solo. Foram investigadas propriedades de carga de superfície de dois Latossolos Vermelhos acriférricos, dois Latossolos Amarelos ácricos e um Nitossolo Vermelho eutroférrico, usado como referência, por apresentar carga predominantemente permanente. Essas amostras foram investigadas pelo método da adsorção do íon césio (Cs+, que mede a carga estrutural permanente (sigmaO. O método baseia-se na preferência de sítios siloxanos de superfície para Cs+ sobre Li+ e de grupos de superfície ionizáveis de menor seletividade ao íon Cs+. Nos Latossolos acriférricos, a carga permanente diminuiu à medida que o índice de intemperização (Ki diminuiu. O método da adsorção de césio quantificou significativa carga permanente, mesmo em solos altamente intemperizados.The knowledge of permanent and variable charge is of high importance to a better understanding of the fate of chemical elements in soil. Four Brazilian Oxisols presenting acric character were investigated by an ion adsorption method that measures the structural charge density (sigmaO and were compared to an Alfisol (NV, which had predominantly permanent charge. The method is based on the preference of siloxane surface sites for cesium over lithium and on the lower selectivity of ionizable surface group for the ion cesium. In the Acrudoxes, the permanent charge decreased as the weathering index (Ki decreased. The cesium adsorption method quantified significant amounts of structural charge, even in highly weathered soils.
Engineering-Based Thermal CFD Simulations on Massive Parallel Systems
Frisch, Jé rô me; Mundani, Ralf-Peter; Rank, Ernst; van Treeck, Christoph
2015-01-01
The development of parallel Computational Fluid Dynamics (CFD) codes is a challenging task that entails efficient parallelization concepts and strategies in order to achieve good scalability values when running those codes on modern supercomputers
Calibration of the k- ɛ model constants for use in CFD applications
Glover, Nina; Guillias, Serge; Malki-Epshtein, Liora
2011-11-01
The k- ɛ turbulence model is a popular choice in CFD modelling due to its robust nature and the fact that it has been well validated. However it has been noted in previous research that the k- ɛ model has problems predicting flow separation as well as unconfined and transient flows. The model contains five empirical model constants whose values were found through data fitting for a wide range of flows (Launder 1972) but ad-hoc adjustments are often made to these values depending on the situation being modeled. Here we use the example of flow within a regular street canyon to perform a Bayesian calibration of the model constants against wind tunnel data. This allows us to assess the sensitivity of the CFD model to changes in these constants, find the most suitable values for the constants as well as quantifying the uncertainty related to the constants and the CFD model as a whole.
CFD analysis and flow model reduction for surfactant production in helix reactor
Directory of Open Access Journals (Sweden)
Nikačević N.M.
2015-01-01
Full Text Available Flow pattern analysis in a spiral Helix reactor is conducted, for the application in the commercial surfactant production. Step change response curves (SCR were obtained from numerical tracer experiments by three-dimensional computational fluid dynamics (CFD simulations. Non-reactive flow is simulated, though viscosity is treated as variable in the direction of flow, as it increases during the reaction. The design and operating parameters (reactor diameter, number of coils and inlet velocity are varied in CFD simulations, in order to examine the effects on the flow pattern. Given that 3D simulations are not practical for fast computations needed for optimization, scale-up and control, CFD flow model is reduced to one-dimensional axial dispersion (AD model with spatially variable dispersion coefficient. Dimensionless dispersion coefficient (Pe is estimated under different conditions and results are analyzed. Finally, correlation which relates Pe number with Reynolds number and number of coils from the reactor entrance is proposed for the particular reactor application and conditions.
Experimental and CFD investigation of gas phase freeboard combustion
DEFF Research Database (Denmark)
Andersen, Jimmy
Reliable and accurate modeling capabilities for combustion systems are valuable tools for optimization of the combustion process. This work concerns primary precautions for reducing NO emissions, thereby abating the detrimental effects known as “acid rain”, and minimizing cost for flue gas...... treatment. The aim of this project is to provide validation data for Computational Fluid Dynamic (CFD) models relevant for grate firing combustion conditions. CFD modeling is a mathematical tool capable of predicting fluid flow, mixing and chemical reaction with thermal conversion and transport. Prediction......, but under well-defined conditions. Comprehensive experimental data for velocity field, temperatures, and gas composition are obtained from a 50 kW axisymmetric non-swirling natural gas fired combustion setup under two different settings. Ammonia is added to the combustion setup in order to simulate fuel...