Thermal response model of free-running buildings = Model toplotnega odziva netermostatiranih stabv

Reducing energy consumption and eliminating wastage are among the main goals of the European Union (EU) [2]. In order to satisfy all challenges arising from the Kyoto protocol, improving energy efficiency is a very important factor to take into account. There is significant potential for reducing consumption with cost-effective measures. Some studies show that 40% of our energy is consumed in buildings, and the EU has introduced legislation that aims to ensure that less energy is consumed in this way in the future.

Efficient numerical methods for global linear instability. Analysis and modeling of non-orthogonal swept attachment-line boundary layer flow

The aim of this thesis is to study the mechanisms of instability that occur in swept wings when the angle of attack increases. For this, a simplified model for the a simplified model for the non-orthogonal swept leading edge boundary layer has been used as well as different numerical techniques in order to solve the linear stability problem that describes the behavior of perturbations superposed upon this base flow. Two different approaches, matrix-free and matrix forming methods, have been validated using direct numerical simulations with spectral resolution. In this way, flow instability in the non-orthogonal swept attachment-line boundary layer is addressed in a linear analysis framework via the solution of the pertinent global (Bi-Global) PDE-based eigenvalue problem. Subsequently, a simple extension of the extended G¨ortler-H¨ammerlin ODEbased polynomial model proposed by Theofilis, Fedorov, Obrist & Dallmann (2003) for orthogonal flow, which includes previous models as particular cases and recovers global instability analysis results, is presented for non-orthogonal flow. Direct numerical simulations have been used to verify the stability results and unravel the limits of validity of the basic flow model analyzed. The effect of the angle of attack, AoA, on the critical conditions of the non-orthogonal problem has been documented; an increase of the angle of attack, from AoA = 0 (orthogonal flow) up to values close to _/2 which make the assumptions under which the basic flow is derived questionable, is found to systematically destabilize the flow. The critical conditions of non-orthogonal flows at 0 _ AoA _ _/2 are shown to be recoverable from those of orthogonal flow, via a simple analytical transformation involving AoA. These results can help to understand the mechanisms of destabilization that occurs in the attachment line of wings at finite angles of attack. Studies taking into account variations of the pressure field in the basic flow or the extension to compressible flows are issues that remain open. El objetivo de esta tesis es estudiar los mecanismos de la inestabilidad que se producen en ciertos dispositivos aerodinámicos cuando se aumenta el ángulo de ataque. Para ello se ha utilizado un modelo simplificado del flujo de base, así como diferentes técnicas numéricas, con el fin de resolver el problema de estabilidad lineal asociado que describe el comportamiento de las perturbaciones. Estos métodos; sin y con formación de matriz, se han validado utilizando simulaciones numéricas directas con resolución espectral. De esta manera, la inestabilidad del flujo de capa límite laminar oblicuo entorno a la línea de estancamiento se aborda en un marco de análisis lineal por medio del método Bi-Global de resolución del problema de valores propios en derivadas parciales. Posteriormente se propone una extensión simple para el flujo no-ortogonal del modelo polinomial de ecuaciones diferenciales ordinarias, G¨ortler-H¨ammerlin extendido, propuesto por Theofilis et al. (2003) para el flujo ortogonal, que incluye los modelos previos como casos particulares y recupera los resultados del analisis global de estabilidad lineal. Se han realizado simulaciones directas con el fin de verificar los resultados del análisis de estabilidad así como para investigar los límites de validez del modelo de flujo base utilizado. En este trabajo se ha documentado el efecto del ángulo de ataque AoA en las condiciones críticas del problema no ortogonal obteniendo que el incremento del ángulo de ataque, de AoA = 0 (flujo ortogonal) hasta valores próximos a _/2, en el cual las hipótesis sobre las que se basa el flujo base dejan de ser válidas, tiende sistemáticamente a desestabilizar el flujo. Las condiciones críticas del caso no ortogonal 0 _ AoA _ _/2 pueden recuperarse a partir del caso ortogonal mediante el uso de una transformación analítica simple que implica el ángulo de ataque AoA. Estos resultados pueden ayudar a comprender los mecanismos de desestabilización que se producen en el borde de ataque de las alas de los aviones a ángulos de ataque finitos. Como tareas pendientes quedaría realizar estudios que tengan en cuenta variaciones del campo de presión en el flujo base así como la extensión de éste al caso de flujos compresibles.

Desarrollo de un modelo para la caracterización termoeconómica de ciclos combinados de turbinas de gas y de vapor en condiciones de carga variable

En la actualidad, el interés por las plantas de potencia de ciclo combinado de gas y vapor ha experimentado un notable aumento debido a su alto rendimiento, bajo coste de generación y rápida construcción. El objetivo fundamental de la tesis es profundizar en el conocimiento de esta tecnología, insuficientemente conocida hasta el momento debido al gran número de grados de libertad que existen en el diseño de este tipo de instalaciones. El estudio se realizó en varias fases. La primera consistió en analizar y estudiar las distintas tecnologías que se pueden emplear en este tipo de centrales, algunas muy recientes o en fase de investigación, como las turbinas de gas de geometría variable, las turbinas de gas refrigeradas con agua o vapor del ciclo de vapor o las calderas de paso único que trabajan con agua en condiciones supercríticas. Posteriormente se elaboraron los modelos matemáticos que permiten la simulación termodinámica de cada uno de los componentes que integran las plantas, tanto en el punto de diseño como a cargas parciales. Al mismo tiempo, se desarrolló una metodología novedosa que permite resolver el sistema de ecuaciones que resulta de la simulación de cualquier configuración posible de ciclo combinado. De esa forma se puede conocer el comportamiento de cualquier planta en cualquier punto de funcionamiento. Por último se desarrolló un modelo de atribución de costes para este tipo de centrales. Con dicho modelo, los estudios se pueden realizar no sólo desde un punto de vista termodinámico sino también termoeconómico, con lo que se pueden encontrar soluciones de compromiso entre rendimiento y coste, asignar costes de producción, determinar curvas de oferta, beneficios económicos de la planta y delimitar el rango de potencias donde la planta es rentable. El programa informático, desarrollado en paralelo con los modelos de simulación, se ha empleado para obtener resultados de forma intensiva. El estudio de los resultados permite profundizar ampliamente en el conocimiento de la tecnología y, así, desarrollar una metodología de diseño de este tipo de plantas bajo un criterio termoeconómico. ABSTRACT The growing energy demand and the need of shrinking costs have led to the design of high efficiency and quick installation power plants. The success of combined cycle gas turbine power plants lies on their high efficiency, low cost and short construction lead time. The main objective of the work is to study in detail this technology, which is not thoroughly known owing to the great number of degrees of freedom that exist in the design of this kind of power plants. The study is divided into three parts. Firstly, the different technologies and components that could be used in any configuration of a combined cycle gas turbine power plant are studied. Some of them could be of recent technology, such as the variable inlet guide vane compressors, the H-technology for gas turbine cooling or the once-through heat recovery steam generators, used with water at supercritical conditions. Secondly, a mathematical model has been developed to simulate at full and part load the components of the power plant. At the same time, a new methodology is proposed in order to solve the equation system resulting for any possible power plant configuration. Therefore, any combined cycle gas turbine could be simulated at any part load condition. Finally a themoeconomic model is proposed. This model allows studying the power plant not only from a thermodynamic point of view but also from a thermoeconomic one. Likewise, it allows determining the generating costs or the cash flow, thus achieving a trade off between efficiency and cost. Likewise, the model calculates the part load range where the power plant is profitable. Once the thermodynamic and thermoeconomic models are developed, they are intensively used in order to gain knowledge in the combined cycle gas turbine technology and, in this way, to propose a methodology aimed at the design of this kind of power plants from a thermoeconomic point of view.

Análisis y optimización de la resistencia de interferencia en multicascos

Esta tesis presenta un estudio de la resistencia de interferencia en multicascos, término que engloba las variaciones en la resistencia al avance debidas a la interacción entre cascos. Su característica más notable es que puede ser tanto positiva como negativa, contribuyendo favorablemente en este último caso a la reducción de la resistencia total. Su análisis permanece como un área activa dentro de la comunidad hidrodinámica, si bien se ha detectado una significativa falta de información experimental sobre el flujo entre cascos. En primer lugar se incluye una caracterización de los fenómenos de interferencia, evaluando su impacto en las diferentes componentes de la resistencia al avance. Al igual que la resistencia total, su predicción requiere el uso de técnicas experimentales o numéricas al ser inviable su solución analítica. Ambos procedimientos han sido considerados en esta tesis. El análisis experimental de la resistencia de interferencia supone el núcleo central del trabajo realizado. Se han ensayado dos geometrías diferentes, un catamarán de servicio comercial PESBO junto con un catamarán compuesto por dos Serie 60 (S60) en paralelo. Los ensayos se han llevado a cabo en dos canales de experiencias, CEHINAV y CEHIPAR, midiéndose resistencia al avance, asiento y trimados dinámicos, y cortes de olas en la zona entre cascos. Mención especial a estos últimos, dado que a pesar de ser en la zona central donde ocurren los principales efectos de interferencia, no se encontró información previa publicada en la literatura. Su medición requirió la fabricación de un sistema de soporte especifico para las probetas de medición. Por otro lado, aunque el Serie 60 es una geometría bien conocida en la comunidad hidrodinámica, a conocimiento del autor su comportamiento como multicasco no había sido aun caracterizado experimentalmente. Los bastidores de unión se fabricaron de forma que permitieran variar la separación entre cascos. Además, los multicascos son en general embarcaciones de alta velocidad mostrando asientos y trimados dinámicos significativos. Para cuantificar su efecto en la resistencia total y de interferencia se construyo un sistema de fijación del modelo al carro que los restringiera, posibilitando comparar los resultados en esta condición con los del modelo libre. Como resultado, se han obtenido resultados experimentales de las dos geometrías estudiadas con múltiples separaciones, incluyendo un solo casco, y con modelo fijo y libre. Una de las principales utilidades de los resultados experimentales es servir como referencia para validar modelos de predicción. Como primera aplicación, los datos experimentales obtenidos con el catamarán S60 se han contrastado con las predicciones numéricas de Yeung et al. (2004). El análisis numérico de la resistencia de interferencia se completa con la realización de simulaciones numéricas utilizando dos códigos substancialmente diferentes: Tdynlin y CD--‐Adapco Star--‐CCM+. Los cortes de olas obtenidos en las simulaciones se comparan con los valores experimentales, mostrándose además los campos de presiones y velocidades calculados sobre el casco. La principal aportación de esta tesis es una extensa caracterización experimental de los fenómenos de interferencia, con la intención de servir de referencia para futuros estudios con multicascos. El análisis de los resultados permite comprender mejor el impacto que la interacción entre cascos, así como las variaciones dinámicas de las condiciones de navegación, tienen en las diferentes componentes de la resistencia. Por otro lado, permite apreciar la dependencia de la resistencia de interferencia con la velocidad y separación entre cascos, de cara a su utilización como parámetro de diseño. ABSTRACT This thesis presents a study of the interference resistance in multihulls, which comprises all the variations in the ship resistance due to the interaction between hulls. Its most remarkable characteristic is that it can be positive or negative, contributing in the second case to the reduction of the total ship resistance. Its study remains an active area in the hydrodynamic community, although there is a significant lack of published experimental data regarding the flow between hulls. First of all, the interference phenomena are characterized, evaluating the impact in the different components of the ship resistance. Similar to the total resistance, their prediction requires experimental or numerical techniques, as no analytic solutions are known. Both procedures have been considered in this thesis. The experimental analysis of the interference resistance is the core of the work done. Two different geometries have been tested, a commercial catamaran PESBO and a catamaran composed by two parallel Series 60 (S60). The tests have been carried out in two towing tanks, CEHINAV and CEHIPAR, measuring ship resistance, dynamic sinkage and trim, and wave cuts in--‐between the hulls. Special mention to the wave cuts, as no previous published information was found regarding this zone, even if it is where the main interference effects happen. Their measurement required building a support tripod for the probes, specifically designed for this experimental campaign. In addition, although the Series 60 is a well known hull for experimental and computational analyses, to the author’s knowledge its behavior as a multihull had not yet been experimentally described. The connection frames between the hulls were built so they allowed adjusting the hull spacing. Furthermore, multihulls are usually high--‐speed vessels, acquiring significant dynamic sinkage and trim. To quantify the effect of these dynamic variations of the interference resistance, a clamping system was developed to fixed the model and compare the results with the free model condition. Thus, experimental results have been obtained for various hull separations with the two geometries analyzed, including a single hull, and with free and fixed model. One of the main applications of experimental results is to serve as a reference to validate prediction models. As a first step, the obtained experimental data with the catamaran S60 have been compared with the numerical predictions of Yeung et al. (2004). The numerical analysis of the interference resistance is completed with the inclusion of numerical simulations using two codes substantially different: Tdynlin and CD--‐Adapco Star--‐CCM+. The wave cuts obtained from the simulations are compared with the experimental ones, showing also the pressure and velocity fields over the hulls. The main contribution of this thesis is an extensive experimental characterization of the interference phenomena, aiming to serve as reference for future studies about multihulls. The analysis of the results provides insights into the impact that the interaction between hulls, as well as the dynamic variations of the sailing conditions, have in the different components of the ship resistance. Moreover, it allows us to observe the dependence of the interference resistance on the velocity and hull spacing, useful towards its use as a design parameter.

Numerical Error Prediction and its applications in CFD using tau-estimation

Nowadays, Computational Fluid Dynamics (CFD) solvers are widely used within the industry to model fluid flow phenomenons. Several fluid flow model equations have been employed in the last decades to simulate and predict forces acting, for example, on different aircraft configurations. Computational time and accuracy are strongly dependent on the fluid flow model equation and the spatial dimension of the problem considered. While simple models based on perfect flows, like panel methods or potential flow models can be very fast to solve, they usually suffer from a poor accuracy in order to simulate real flows (transonic, viscous). On the other hand, more complex models such as the full Navier- Stokes equations provide high fidelity predictions but at a much higher computational cost. Thus, a good compromise between accuracy and computational time has to be fixed for engineering applications. A discretisation technique widely used within the industry is the so-called Finite Volume approach on unstructured meshes. This technique spatially discretises the flow motion equations onto a set of elements which form a mesh, a discrete representation of the continuous domain. Using this approach, for a given flow model equation, the accuracy and computational time mainly depend on the distribution of nodes forming the mesh. Therefore, a good compromise between accuracy and computational time might be obtained by carefully defining the mesh. However, defining an optimal mesh for complex flows and geometries requires a very high level expertize in fluid mechanics and numerical analysis, and in most cases a simple guess of regions of the computational domain which might affect the most the accuracy is impossible. Thus, it is desirable to have an automatized remeshing tool, which is more flexible with unstructured meshes than its structured counterpart. However, adaptive methods currently in use still have an opened question: how to efficiently drive the adaptation ? Pioneering sensors based on flow features generally suffer from a lack of reliability, so in the last decade more effort has been made in developing numerical error-based sensors, like for instance the adjoint-based adaptation sensors. While very efficient at adapting meshes for a given functional output, the latter method is very expensive as it requires to solve a dual set of equations and computes the sensor on an embedded mesh. Therefore, it would be desirable to develop a more affordable numerical error estimation method. The current work aims at estimating the truncation error, which arises when discretising a partial differential equation. These are the higher order terms neglected in the construction of the numerical scheme. The truncation error provides very useful information as it is strongly related to the flow model equation and its discretisation. On one hand, it is a very reliable measure of the quality of the mesh, therefore very useful in order to drive a mesh adaptation procedure. On the other hand, it is strongly linked to the flow model equation, so that a careful estimation actually gives information on how well a given equation is solved, which may be useful in the context of _ -extrapolation or zonal modelling. The following work is organized as follows: Chap. 1 contains a short review of mesh adaptation techniques as well as numerical error prediction. In the first section, Sec. 1.1, the basic refinement strategies are reviewed and the main contribution to structured and unstructured mesh adaptation are presented. Sec. 1.2 introduces the definitions of errors encountered when solving Computational Fluid Dynamics problems and reviews the most common approaches to predict them. Chap. 2 is devoted to the mathematical formulation of truncation error estimation in the context of finite volume methodology, as well as a complete verification procedure. Several features are studied, such as the influence of grid non-uniformities, non-linearity, boundary conditions and non-converged numerical solutions. This verification part has been submitted and accepted for publication in the Journal of Computational Physics. Chap. 3 presents a mesh adaptation algorithm based on truncation error estimates and compares the results to a feature-based and an adjoint-based sensor (in collaboration with Jorge Ponsín, INTA). Two- and three-dimensional cases relevant for validation in the aeronautical industry are considered. This part has been submitted and accepted in the AIAA Journal. An extension to Reynolds Averaged Navier- Stokes equations is also included, where _ -estimation-based mesh adaptation and _ -extrapolation are applied to viscous wing profiles. The latter has been submitted in the Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering. Keywords: mesh adaptation, numerical error prediction, finite volume Hoy en día, la Dinámica de Fluidos Computacional (CFD) es ampliamente utilizada dentro de la industria para obtener información sobre fenómenos fluidos. La Dinámica de Fluidos Computacional considera distintas modelizaciones de las ecuaciones fluidas (Potencial, Euler, Navier-Stokes, etc) para simular y predecir las fuerzas que actúan, por ejemplo, sobre una configuración de aeronave. El tiempo de cálculo y la precisión en la solución depende en gran medida de los modelos utilizados, así como de la dimensión espacial del problema considerado. Mientras que modelos simples basados en flujos perfectos, como modelos de flujos potenciales, se pueden resolver rápidamente, por lo general aducen de una baja precisión a la hora de simular flujos reales (viscosos, transónicos, etc). Por otro lado, modelos más complejos tales como el conjunto de ecuaciones de Navier-Stokes proporcionan predicciones de alta fidelidad, a expensas de un coste computacional mucho más elevado. Por lo tanto, en términos de aplicaciones de ingeniería se debe fijar un buen compromiso entre precisión y tiempo de cálculo. Una técnica de discretización ampliamente utilizada en la industria es el método de los Volúmenes Finitos en mallas no estructuradas. Esta técnica discretiza espacialmente las ecuaciones del movimiento del flujo sobre un conjunto de elementos que forman una malla, una representación discreta del dominio continuo. Utilizando este enfoque, para una ecuación de flujo dado, la precisión y el tiempo computacional dependen principalmente de la distribución de los nodos que forman la malla. Por consiguiente, un buen compromiso entre precisión y tiempo de cálculo se podría obtener definiendo cuidadosamente la malla, concentrando sus elementos en aquellas zonas donde sea estrictamente necesario. Sin embargo, la definición de una malla óptima para corrientes y geometrías complejas requiere un nivel muy alto de experiencia en la mecánica de fluidos y el análisis numérico, así como un conocimiento previo de la solución. Aspecto que en la mayoría de los casos no está disponible. Por tanto, es deseable tener una herramienta que permita adaptar los elementos de malla de forma automática, acorde a la solución fluida (remallado). Esta herramienta es generalmente más flexible en mallas no estructuradas que con su homóloga estructurada. No obstante, los métodos de adaptación actualmente en uso todavía dejan una pregunta abierta: cómo conducir de manera eficiente la adaptación. Sensores pioneros basados en las características del flujo en general, adolecen de una falta de fiabilidad, por lo que en la última década se han realizado grandes esfuerzos en el desarrollo numérico de sensores basados en el error, como por ejemplo los sensores basados en el adjunto. A pesar de ser muy eficientes en la adaptación de mallas para un determinado funcional, este último método resulta muy costoso, pues requiere resolver un doble conjunto de ecuaciones: la solución y su adjunta. Por tanto, es deseable desarrollar un método numérico de estimación de error más asequible. El presente trabajo tiene como objetivo estimar el error local de truncación, que aparece cuando se discretiza una ecuación en derivadas parciales. Estos son los términos de orden superior olvidados en la construcción del esquema numérico. El error de truncación proporciona una información muy útil sobre la solución: es una medida muy fiable de la calidad de la malla, obteniendo información que permite llevar a cabo un procedimiento de adaptación de malla. Está fuertemente relacionado al modelo matemático fluido, de modo que una estimación precisa garantiza la idoneidad de dicho modelo en un campo fluido, lo que puede ser útil en el contexto de modelado zonal. Por último, permite mejorar la precisión de la solución resolviendo un nuevo sistema donde el error local actúa como término fuente (_ -extrapolación). El presenta trabajo se organiza de la siguiente manera: Cap. 1 contiene una breve reseña de las técnicas de adaptación de malla, así como de los métodos de predicción de los errores numéricos. En la primera sección, Sec. 1.1, se examinan las estrategias básicas de refinamiento y se presenta la principal contribución a la adaptación de malla estructurada y no estructurada. Sec 1.2 introduce las definiciones de los errores encontrados en la resolución de problemas de Dinámica Computacional de Fluidos y se examinan los enfoques más comunes para predecirlos. Cap. 2 está dedicado a la formulación matemática de la estimación del error de truncación en el contexto de la metodología de Volúmenes Finitos, así como a un procedimiento de verificación completo. Se estudian varias características que influyen en su estimación: la influencia de la falta de uniformidad de la malla, el efecto de las no linealidades del modelo matemático, diferentes condiciones de contorno y soluciones numéricas no convergidas. Esta parte de verificación ha sido presentada y aceptada para su publicación en el Journal of Computational Physics. Cap. 3 presenta un algoritmo de adaptación de malla basado en la estimación del error de truncación y compara los resultados con sensores de featured-based y adjointbased (en colaboración con Jorge Ponsín del INTA). Se consideran casos en dos y tres dimensiones, relevantes para la validación en la industria aeronáutica. Este trabajo ha sido presentado y aceptado en el AIAA Journal. También se incluye una extensión de estos métodos a las ecuaciones RANS (Reynolds Average Navier- Stokes), en donde adaptación de malla basada en _ y _ -extrapolación son aplicados a perfiles con viscosidad de alas. Este último trabajo se ha presentado en los Actas de la Institución de Ingenieros Mecánicos, Parte G: Journal of Aerospace Engineering. Palabras clave: adaptación de malla, predicción del error numérico, volúmenes finitos

Prediction of near field overpressure from quarry blasting

This paper investigates the propagation of airblast or pressure waves in air produced by bench blasting (i.e. detonation of the explosive in a row of blastholes, breaking the burden of rock towards the free vertical face of the block). Peak overpressure is calculated as a function of blasting parameters (explosive mass per delay and velocity at which the detonation sequence proceeds along the bench) and the polar coordinates of the position of interest (distance to the source and azimuth with respect to the free face). The model has been fitted to empirical data using linear least squares. The data set is composed of 122 airblast records monitored at distances less than 400 m in 41 production blasts carried out in two quarries. The model is statistically significant and has a determination coefficient of 0.87. The formula is validated from 12 airblast measurements gathered in five additional blasts.

Simulación de componentes no estacionarias de viento en orografías complejas

Realistic operation of helicopter flight simulators in complex topographies (such as urban environments) requires appropriate prediction of the incoming wind, and this prediction should be made in real time. Unfortunately, the wind topology around complex topographies shows time-dependent, fully nonlinear, turbulent patterns (i.e., wakes) whose simulation cannot be made using computationally inexpensive tools based on corrected potential approximations. Instead, the full Navier-Stokes plus some kind of turbulent modeling is necessary, which is quite computationally expensive. The complete unsteady flow depends on two parameters, namely the velocity and orientation of the free stream flow. The aim of this MSc thesis is to develop a methodology for the real time simulation of these complex flows. For simplicity, the flow around a single building (20 mx20 m cross section and 100 m height) is considered, with free stream velocity in the range 5-25 m/s. Because of the square cross section, the problem shows two reflection symmetries, which allows for restricting the orientations to the range 0° < a. < 45°. The methodology includes an offline preprocess and the online operation. The preprocess consists in three steps: An appropriate, unstructured mesh is selected in which the flow is sim¬ulated using OpenFOAM, and this is done for 33 combinations of 3 free stream intensities and 11 orientations. For each of these, the simulation proceeds for a sufficiently large time as to eliminate transients. This step is quite computationally expensive. Each flow field is post-processed using a combination of proper orthogonal decomposition, fast Fourier transform, and a convenient optimization tool, which identifies the relevant frequencies (namely, both the basic frequencies and their harmonics) and modes in the computational mesh. This combination includes several new ingredients to filter errors out and identify the relevant spatio-temporal patterns. Note that, in principle, the basic frequencies depend on both the intensity and the orientation of the free stream flow. The outcome of this step is a set of modes (vectors containing the three velocity components at all mesh points) for the various Fourier components, intensities, and orientations, which can be organized as a third order tensor. This step is fairly computationally inexpensive. The above mentioned tensor is treated using a combination of truncated high order singular value, decomposition and appropriate one-dimensional interpolation (as in Lorente, Velazquez, Vega, J. Aircraft, 45 (2008) 1779-1788). The outcome is a tensor representation of both the relevant fre¬quencies and the associated Fourier modes for a given pair of values of the free stream flow intensity and orientation. This step is fairly compu¬tationally inexpensive. The online, operation requires just reconstructing the time-dependent flow field from its Fourier representation, which is extremely computationally inex¬pensive. The whole method is quite robust.

Consultoría en el marco económico-financiero de la empresa

Muchas de las grandes iniciativas empresariales, se ven truncadas por falta de un adecuado análisis económico-financiero. Incluso, muchas grandes ideas no son implantadas correctamente en el primer intento por este motivo, y son otras personas las que consiguen posteriormente el éxito de esas brillantes ideas gracias a una correcta aproximación financiera. Las empresas necesitan definir sus objetivos, establecer las para lograrlos, identificar las personas responsables de su ejecución (sus roles y funciones) y elaborar un plan económico-financiero que recoja el estudio de inversiones necesarias, el análisis de costes, la previsión de ingresos, así como la estrategia financiera más adecuada para la captación de los fondos necesarios para llevar a cabo las acciones programadas. Una vez iniciado el proyecto empresarial, será imprescindible realizar un seguimiento y control de la evolución (integración), tomando las medidas que se estimen oportunas para mantener el rumbo adecuado durante todo el tiempo de actividad. En este trabajo, aplicaremos las metodologías y buenas prácticas de la gestión de proyectos, como marco estructurado que nos permita abordar las principales cuestiones económico-financieras a tener en cuenta a la hora de enfrentarnos a un proyecto empresarial, para contribuir, en la medida de lo posible, a que los emprendedores tengan en cuenta estas cuestiones, facilitando así el desarrollo de negocios, en un difícil entorno económico de crisis como el que actualmente estamos viviendo en España, y animando de esta manera a optar por la iniciativa emprendedora, tratando de minimizar el riesgo en base al contenido. ---ABSTRACT---Lack of adequate economic and financial analysis truncates many of the entrepreneurship and innovation programs. Because of that reason, many great ideas are not even correctly implemented on the first attempt, and the person who finds the proper financial approach, succeed. All the enterprises have to establish clear objectives, actions to accomplish those objectives, assign roles, responsibilities and executive functions to specific people. Elaborate funding plan that contains surveys on necessary investments, cost analysis, estimate the income, liquid assets and also financial strategy suitable for fundraising to finance programmed actions. Once the project has been executed it is essential to monitor and control the development and integration adopting measures accordingly to the needs. This thesis applies methodology and best practice of project management as structured framework for the principal economic and financial issues facing business project. It is necessary contribution to entrepreneurs understanding of business, therefore facilitates business development in such rough environment as Spain is at this moment, and at the same time encourages adopting entrepreneur’s solution as less risky one. This document aims to explore all the economic and financial issues from methodological point of view based on my own professional experience, resulting in helping to understand the importance that economy and finances have in developing adequate corporate strategy. Crisis has highlighted inadequate functionality of many companies. Most popular first symptom is lack of cash flow that deteriorates the company, and results in suspension of payments followed by closing. In other cases, difficulties appear due to poor financial management of committed resources; to be observed in lack of prevision and planning or incorrect basic functionality and operational matters on daily basis. What would be your advice to someone who have magnificent business idea however no knowledge on how to handle finances in order to succeed in initiating and executing the project? Despite of the fact that the central nucleus of this paper is at economics and finances area, all the other concepts and topics given during master will be revived; for example business strategy, consultants abilities, organization and standard processes, among others, are impregnated with knowledge of project management.

Terremoto 2010 en Chile y vivienda social: resultados y aprendizajes para recomendación de políticas públicas

El territorio chileno esta propenso, desde antes que se constituyera como nación, al impacto del comportamiento de la naturaleza que le es inherente y que también le produce daños. Está representado en los seísmos, los más dañinos. Todavía, la sociedad chilena no termina de comprender que esos daños, son parte de un desequilibrio de una convivencia armoniosa entre ella y esa naturaleza, puesto que el ser humano que vive y habita sobre ella, también lo es. Así entonces, cada vez que el territorio y su espacio son remecidos por los seísmos, la naturaleza, manifestada en la sociedad, adquiere nuevos aprendizajes para mejorar la respuesta al próximo evento. El terremoto 2010 de 8.8° Richter, fue el segundo de mayor magnitud después del otro que hasta ahora, es el más grande del planeta, y que pudo ser medido. Aquel, fue el terremoto de Valdivia de 9,5° Richter, ocurrido el 22 de mayo de 1960. Las sociedades no son estáticas, cambian, son dinámicas. Esta vez el seísmo del 2010, ocurrió en una sociedad que hace ya 35 años, adoptó un modelo de economía de libre mercado. La pobreza que tenía a 1990, era de aproximadamente, un 40%. La del 2010, de un 14%. Durante la dictadura militar hubo otro seísmo de 7,8° Richter, recién instalándose el modelo aludido. El del 2010, permite sacar conclusiones en el contexto de este modelo económico. Los resultados aparentemente son interesantes en cuanto a que hubo pocas víctimas pero por otra parte, hubo un gran daño económico. La tesis profundiza en el impacto del seísmo en la dimensión del parque habitacional construido y de la vivienda social y en los habitantes más pobres y vulnerables. Es la primera investigación sobre seísmos y vivienda social en Chile. Se asume la hipótesis que ciertas variables por una parte, y una cultura antisísmica por otra, están presentes y han penetrado en los sectores populares durante los últimos 50 años y que ello, podría estar en la base de los resultados obtenidos. Se plantea una suerte de “matrimonio bien avenido” entre el habitante y políticas públicas en vivienda. De ello, se derivan recomendaciones para mejorar los avances en el problema investigado que se contextualizan en referencia al marco teórico elaborado. Sin embargo, y no obstante lo investigado, lo ya avanzado no garantiza buenos resultados en el próximo evento, Por ello, los aprendizajes nutren a otros, nuevos, que acompañarán a la sociedad chilena en su esencia e identidad como nación. ABSTRACT Long before its establishment as an independent nation, the Chilean territory has been prone to the impact of nature, which is an inherent and damaging feature of this land. Such an impact is represented by earthquakes, which are regarded as the most damaging natural disasters. Today, the Chilean society is still unable to understand that these impacts are part of an unbalanced coexistence between individuals and nature since human beings, who live and inhabit this space, are also an element of nature. Therefore, each time this territory is hit by earthquakes, nature —represented by society— learns new lessons in order to provide a better response to future events. The 2010 earthquake, which rated 8.8 on the Richter scale, was the second largest earthquake after the most powerful earthquake ever recorded. Such an event was the Valdivia earthquake of May 22, 1960, which rated 9.5 on the Richter scale. Societies are not static as they are changing and dynamic. The 2010 earthquake took place within a context in which society operated under a free market economy model that had been running for 35 years. As of 1990, 40 per cent of the population lived in poverty; in 2010, such a figure was reduced to 14 per cent. Likewise, a magnitude 7.8 quake struck the country during the military regime period in the early days of the above model. The 2010 earthquake allows us to draw some conclusions within the context of this economic model. Results are interesting since there were few fatalities but significant economic loss. This thesis provides insights into the impact of the 2010 earthquake on the housing stock, social housing and those living in poverty and vulnerability. This is the first research on earthquakes and social housing conducted in Chile. The hypothesis is that certain variables and anti-seismic culture have permeated popular segments of the population over the last 50 years. The latter may be at the basis of the results obtained during this research. Likewise, this study proposes a certain “happy marriage” between the inhabitant and public policies on housing. The above offers some recommendations intended to further explore this issue; these suggestions are contextualized according to the theoretical framework developed in this research. However, current progress on this matter does not ensure positive results in the event of an earthquake. This is why these lessons will serve as models for future events, which are intrinsically tied to local society and Chilean identity.

A two-dimensional finite element model of front surface current flow in cells under non-uniform, concentrated illumination

A two-dimensional finite element model of current flow in the front surface of a PV cell is presented. In order to validate this model we perform an experimental test. Later, particular attention is paid to the effects of non-uniform illumination in the finger direction which is typical in a linear concentrator system. Fill factor, open circuit voltage and efficiency are shown to decrease with increasing degree of non-uniform illumination. It is shown that these detrimental effects can be mitigated significantly by reoptimization of the number of front surface metallization fingers to suit the degree of non-uniformity. The behavior of current flow in the front surface of a cell operating at open circuit voltage under non-uniform illumination is discussed in detail.

Optimization of a label-free biosensor vertically characterized based on a periodic lattice of high aspect ratio SU-8 nano-pillars with a simplified 2D theoretical model

We have recently demonstrated a biosensor based on a lattice of SU8 pillars on a 1 μm SiO2/Si wafer by measuring vertically reflectivity as a function of wavelength. The biodetection has been proven with the combination of Bovine Serum Albumin (BSA) protein and its antibody (antiBSA). A BSA layer is attached to the pillars; the biorecognition of antiBSA involves a shift in the reflectivity curve, related with the concentration of antiBSA. A detection limit in the order of 2 ng/ml is achieved for a rhombic lattice of pillars with a lattice parameter (a) of 800 nm, a height (h) of 420 nm and a diameter(d) of 200 nm. These results correlate with calculations using 3D-finite difference time domain method. A 2D simplified model is proposed, consisting of a multilayer model where the pillars are turned into a 420 nm layer with an effective refractive index obtained by using Beam Propagation Method (BPM) algorithm. Results provided by this model are in good correlation with experimental data, reaching a reduction in time from one day to 15 minutes, giving a fast but accurate tool to optimize the design and maximizing sensitivity, and allows analyzing the influence of different variables (diameter, height and lattice parameter). Sensitivity is obtained for a variety of configurations, reaching a limit of detection under 1 ng/ml. Optimum design is not only chosen because of its sensitivity but also its feasibility, both from fabrication (limited by aspect ratio and proximity of the pillars) and fluidic point of view. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Proposal of an Alternative Model for Speed-Flow Relationship in Two-Lane Highways

A research has been carried out in two-lanehighways in the Madrid Region to propose an alternativemodel for the speed-flowrelationship using regular loop data. The model is different in shape and, in some cases, slopes with respect to the contents of Highway Capacity Manual (HCM). A model is proposed for a mountainous area road, something for which the HCM does not provide explicitly a solution. The problem of a mountain road with high flows to access a popular recreational area is discussed, and some solutions are proposed. Up to 7 one-way sections of two-lanehighways have been selected, aiming at covering a significant number of different characteristics, to verify the proposed method the different classes of highways on which the Manual classifies them. In order to enunciate the model and to verify the basic variables of these types of roads a high number of data have been used. The counts were collected in the same way that the Madrid Region Highway Agency performs their counts. A total of 1.471 hours have been collected, in periods of 5 minutes. The models have been verified by means of specific statistical test (R2, T-Student, Durbin-Watson, ANOVA, etc.) and with the diagnostics of the contrast of assumptions (normality, linearity, homoscedasticity and independence). The model proposed for this type of highways with base conditions, can explain the different behaviors as traffic volumes increase, and follows a polynomial multiple regression model of order 3, S shaped. As secondary results of this research, the levels of service and the capacities of this road have been measured with the 2000 HCM methodology, and the results discussed. © 2011 Published by Elsevier Ltd.

Flow and wakes in complex terrain and offshore. Model development and verification in UPWIND

The paper presents research conducted in the Flow workpackage of the EU funded UPWIND project which focuses on improving models for flow within and downwind of large wind farms in complex terrain and offshore. The main activity is modelling the behaviour of wind turbine wakes in order to improve power output predictions.

Two-temperature model of the coronal irradiated pellets

A two electron-temperature, quasi-steady model of the corona of a laser-ablated pellet is considered. Ablation pressure, critical radius and mass flow rate are determined. Results are close to those obtained with heat flux saturation well below the free-streaming limit.

Spatial linear global instability analysis of the HIFiRE-5 elliptic cone model flow

The linear instability of the three-dimensional boundary-layer over the HIFiRE-5 flight test geometry, i.e. a rounded-tip 2:1 elliptic cone, at Mach 7, has been analyzed through spatial BiGlobal analysis, in a effort to understand transition and accurately predict local heat loads on next-generation ight vehicles. The results at an intermediate axial section of the cone, Re x = 8x10 5, show three different families of spatially amplied linear global modes, the attachment-line and cross- ow modes known from earlier analyses, and a new global mode, peaking in the vicinity of the minor axis of the cone, termed \center-line mode". We discover that a sequence of symmetric and anti-symmetric centerline modes exist and, for the basic ow at hand, are maximally amplied around F* = 130kHz. The wavenumbers and spatial distribution of amplitude functions of the centerline modes are documented