Quasi-cylindrical approximation to the swirling flow in an atomizer chamber

A quasi-cylindrical approximation is used to analyse the axisymmetric swirling flow of a liquid with a hollow air core in the chamber of a pressure swirl atomizer. The liquid is injected into the chamber with an azimuthal velocity component through a number of slots at the periphery of one end of the chamber, and flows out as an anular sheet through a central orifice at the other end, following a conical convergence of the chamber wall. An effective inlet condition is used to model the effects of the slots and the boundary layer that develops at the nearby endwall of the chamber. An analysis is presented of the structure of the liquid sheet at the end of the exit orifice, where the flow becomes critical in the sense that upstream propagation of long-wave perturbations ceases to be possible. This nalysis leads to a boundary condition at the end of the orifice that is an extension of the condition of maximum flux used with irrotational models of the flow. As is well known, the radial pressure gradient induced by the swirling flow in the bulk of the chamber causes the overpressure that drives the liquid towards the exit orifice, and also leads to Ekman pumping in the boundary layers of reduced azimuthal velocity at the convergent wall of the chamber and at the wall opposite to the exit orifice. The numerical results confirm the important role played by the boundary layers. They make the thickness of the liquid sheet at the end of the orifice larger than predicted by rrotational models, and at the same time tend to decrease the overpressure required to pass a given flow rate through the chamber, because the large axial velocity in the boundary layers takes care of part of the flow rate. The thickness of the boundary layers increases when the atomizer constant (the inverse of a swirl number, proportional to the flow rate scaled with the radius of the exit orifice and the circulation around the air core) decreases. A minimum value of this parameter is found below which the layer of reduced azimuthal velocity around the air core prevents the pressure from increasing and steadily driving the flow through the exit orifice. The effects of other parameters not accounted for by irrotational models are also analysed in terms of their influence on the boundary layers.

Análisis de elementos viga-columna en régimen no lineal con deformación por cortante

El hormigón estructural sigue siendo sin duda uno de los materiales más utilizados en construcción debido a su resistencia, rigidez y flexibilidad para diseñar estructuras. El cálculo de estructuras de hormigón, utilizando vigas y vigas-columna, es complejo debido a los fenómenos de acoplamiento entre esfuerzos y al comportamiento no lineal del material. Los modelos más empleados para su análisis son el de Bernoulli-Euler y el de Timoshenko, indicándose en la literatura la conveniencia de usar el segundo cuando la relación canto/luz no es pequeña o los elementos están fuertemente armados. El objetivo fundamental de esta tesis es el análisis de elementos viga y viga-columna en régimen no lineal con deformación por cortante, aplicando el concepto de Pieza Lineal Equivalente (PLE). Concepto éste que consiste básicamente en resolver el problema de una pieza en régimen no lineal, transformándolo en uno lineal equivalente, de modo que ambas piezas tengan la misma deformada y los mismos esfuerzos. Para ello, se hizo en primer lugar un estudio comparado de: las distintas propuestas que aplican la deformación por cortante, de los distintos modelos constitutivos y seccionales del hormigón estructural y de los métodos de cálculo no lineal aplicando el método de elementos finitos (MEF). Teniendo en cuenta que la resolución del problema no lineal se basa en la resolución de sucesivos problemas lineales empleando un proceso de homotopía, los problemas lineales de la viga y viga-columna de Timoshenko, se resuelven mediante MEF, utilizando soluciones nodalmente exactas (SNE) y acción repartida equivalente de cualquier orden. Se obtiene así, con muy pocos elementos finitos, una excelente aproximación de la solución, no sólo en los nodos sino en el interior de los elementos. Se introduce el concepto PLE para el análisis de una barra, de material no lineal, sometida a acciones axiales, y se extiende el mismo para el análisis no lineal de vigas y vigas-columna con deformación por cortante. Cabe señalar que para estos últimos, la solución de una pieza en régimen no lineal es igual a la de una en régimen lineal, cuyas rigideces son constantes a trozos, y donde además hay que añadir momentos y cargas puntuales ficticias en los nodos, así como, un momento distribuido ficticio en toda la pieza. Se han desarrollado dos métodos para el análisis: uno para problemas isostáticos y otro general, aplicable tanto a problemas isostáticos como hiperestáticos. El primero determina de entrada la PLE, realizándose a continuación el cálculo por MEF-SNE de dicha pieza, que ahora está en régimen lineal. El general utiliza una homotopía que transforma de manera iterativa, unas leyes constitutivas lineales en las leyes no lineales del material. Cuando se combina con el MEF, la pieza lineal equivalente y la solución del problema original quedan determinadas al final de todo el proceso. Si bien el método general es un procedimiento próximo al de Newton- Raphson, presenta sobre éste la ventaja de permitir visualizar las deformaciones de la pieza en régimen no lineal, de manera tanto cualitativa como cuantitativa, ya que es posible observar en cada paso del proceso la modificación de rigideces (a flexión y cortante) y asimismo la evolución de las acciones ficticias. Por otra parte, los resultados obtenidos comparados con los publicados en la literatura, indican que el concepto PLE ofrece una forma directa y eficiente para analizar con muy buena precisión los problemas asociados a vigas y vigas-columna en las que por su tipología los efectos del cortante no pueden ser despreciados. ABSTRACT The structural concrete clearly remains the most used material in construction due to its strength, rigidity and structural design flexibility. The calculation of concrete structures using beams and beam-column is complex as consequence of the coupling phenomena between stresses and of its nonlinear behaviour. The models most commonly used for analysis are the Bernoulli-Euler and Timoshenko. The second model is strongly recommended when the relationship thickness/span is not small or in case the elements are heavily reinforced. The main objective of this thesis is to analyse the beam and beam-column elements with shear deformation in nonlinear regime, applying the concept of Equivalent Linear Structural Element (ELSE). This concept is basically to solve the problem of a structural element in nonlinear regime, transforming it into an equivalent linear structural element, so that both elements have the same deformations and the same stresses. Firstly, a comparative study of the various proposals of applying shear deformation, of various constitutive and sectional models of structural concrete, and of the nonlinear calculation methods (using finite element methods) was carried out. Considering that the resolution of nonlinear problem is based on solving the successive linear problem, using homotopy process, the linear problem of Timoshenko beam and beam-columns is resolved by FEM, using the exact nodal solutions (ENS) and equivalent distributed load of any order. Thus, the accurate solution approximation can be obtained with very few finite elements for not only nodes, but also for inside of elements. The concept ELSE is introduced to analyse a bar of nonlinear material, subjected to axial forces. The same bar is then used for other nonlinear beam and beam-column analysis with shear deformation. It is noted that, for the last analyses, the solution of a structural element in nonlinear regime is equal to that of linear regime, in which the piecewise-stiffness is constant, the moments and fictitious point loads need to be added at nodes of each element, as well as the fictitious distributed moment on element. Two methods have been developed for analysis: one for isostatic problem and other more general, applicable for both isostatic and hiperstatic problem. The first method determines the ELSE, and then the calculation of this piece is performed by FEM-ENS that now is in linear regime. The general method uses the homotopy that transforms iteratively linear constitutive laws into nonlinear laws of material. When combined with FEM, the ELSE and the solution of the original problem are determined at the end of the whole process. The general method is well known as a procedure closed to Newton-Raphson procedure but presents an advantage that allows displaying deformations of the piece in nonlinear regime, in both qualitative and quantitative way. Since it is possible to observe the modification of stiffness (flexural and shear) in each step of process and also the evolution of the fictitious actions. Moreover, the results compared with those published in the literature indicate that the ELSE concept offers a direct and efficient way to analyze with very good accuracy the problems associated with beams and beams columns in which, by typology, the effects of shear cannot be neglected.

Use of Headed Reinforcement Bars in Contruction. A Theoretical Approach to Determine the Dimensions of Anchorage Plates and Experimental Tests on Knee Joints Subjected to a Closing Moment

In order to reduce costs and time while improving quality, durability and sustainability in structural concrete constructions, a widely used material nowadays, special care must be taken in some crucial phases of the project and execution, including the structure design and calculation, the dosage, dumping and curing of concrete: another important aspect is the proper design and execution of assembly plans and construction details. The framework, a name designating the whole reinforcement bars cage already assembled as shown in the drawings, can be made up of several components and implies higher or lower industrialization degree. The framework costs constitute about one third of the price per cubic meter placed in concrete works. The best solutions from all points of view are clearly those involving an easier processing to achieve the same goal, and consequently carrying a high degree of industrialization, meaning quality and safety in the work. This thesis aims to provide an indepth analysis of a relatively new type of anchoring by plate known as headed reinforcement bars, which can potentially replace standard or L-shaped hooks, improving the cleaning of construction details and enabling a faster, more flexible, and therefore a more economical assembly. A literature review on the topic and an overview of typical applications is provided, followed by some examples of specific applications in real projects. Since a strict theoretical formulation used to provide the design plate dimensions has not yet been put forward, an equation is proposed for the side-face blowout strength of the anchorage, based on the capacity of concrete to carry concentrated loads in cases in which no transverse reinforcement is provided. The correlation of the calculated ultimate load with experimental results available in the literature is given. Besides, the proposed formulation can be expanded to cases in which a certain development length is available: using a software for nonlinear finite element analysis oriented to the study of reinforced concrete, numerical tests on the bond-bearing interaction are performed. The thesis ends with a testing of eight corner joints subjected to a closing moment, held in the Structures Laboratory of the Polytechnic University of Madrid, aiming to check whether the design of such plates as stated is adequate for these elements and whether an element with plate-anchored reinforcement is equivalent to one with a traditional construction detail.

Optimal Piecewise Linear Function Approximation for GPU-based Applications

Many computer vision and human-computer interaction applications developed in recent years need evaluating complex and continuous mathematical functions as an essential step toward proper operation. However, rigorous evaluation of this kind of functions often implies a very high computational cost, unacceptable in real-time applications. To alleviate this problem, functions are commonly approximated by simpler piecewise-polynomial representations. Following this idea, we propose a novel, efficient, and practical technique to evaluate complex and continuous functions using a nearly optimal design of two types of piecewise linear approximations in the case of a large budget of evaluation subintervals. To this end, we develop a thorough error analysis that yields asymptotically tight bounds to accurately quantify the approximation performance of both representations. It provides an improvement upon previous error estimates and allows the user to control the trade-off between the approximation error and the number of evaluation subintervals. To guarantee real-time operation, the method is suitable for, but not limited to, an efficient implementation in modern Graphics Processing Units (GPUs), where it outperforms previous alternative approaches by exploiting the fixed-function interpolation routines present in their texture units. The proposed technique is a perfect match for any application requiring the evaluation of continuous functions, we have measured in detail its quality and efficiency on several functions, and, in particular, the Gaussian function because it is extensively used in many areas of computer vision and cybernetics, and it is expensive to evaluate.

Edén: relato, imagen y proyecto. El concepto de paraíso terrenal como generador de arquitecturas

Esta tesis, Edén: relato, imagen y proyecto. El concepto de Paraíso terrenal como generador de arquitecturas se realiza con el objetivo de estudiar los vínculos entre la idea de Edén, o Paraíso y la arquitectura. Siempre trabajando desde los tres niveles de representación, relato, imagen y proyecto. En la aproximación al objeto de estudio, se procede a estudiar el relato en sí, y se hallan, en la forma misma del relato, unas implicaciones relacionadas con el mundo mitológico y arquetípico. Estos resultados iniciales son la detección de que cada una de las partes que forman el conjunto edénico, han sido previamente objetos de culto en religiones corte pagano o chamánico, desde la prehistoria. El agua, los árboles, los animales, la tierra y los surcos del huerto, todos ellos han sido objetos de veneración desde tiempos inmemoriales. Trazando la genealogía de estos objetos de culto se acude al análisis arquetípico, que relaciona estos objetos venerados con el inconsciente y con la manifestación espontanea de los mismos en la realidad. Estos estudios arrojan resultados con implicaciones espaciales, arquitectónicas y se concluye que más que un ideal o un lugar en concreto, en el mito o en la realidad, lo que definitivamente parece (y demuestra) ser, es una tipología arquitectónica relacionada en su estructura formal y teórica con la del jardín cerrado. La manifestación en imagen de estos resultados y la investigación misma, llevan a acudir a unas de las imágenes más primitivas del Jardín del Edén, y que de hecho son previas a la “invención” del Hortus Conclusus como tal. Estas son las representaciones mozárabes del Paraíso Terrenal como lugar cierto en la tierra, que aparecen en los mappaemundi incluidos en los Códices de los Beatos. En el estudio de los mismos se comprende la estructura formal y teórica de lo que son las arquitecturas paradisíacas. Su calado en la cultura occidental hace que estos documentos sirvan como exoesqueletos del proyecto paradisíaco. Además, por su variedad arrojan gran número de resultados de índole espacial. Los resultados arrojados por el estudio de las representaciones edénicas de los Beatos llevan la investigación a otro momento e imágenes de la historia de la arquitectura donde, por su radicalidad de planteamientos y tabula rasa con las arquitecturas previas son necesarios nuevos lenguajes de aproximación al tema proyectual por el deseo globalizador que implican estas arquitecturas, esto es en el periodo de la arquitectura moderna. Se utiliza como elemento calibrador El poema del ángulo recto de Le Corbusier. Este documento gráfico no sólo nos da la clave que bullía en este periodo con respecto a una nueva aproximación a la superficie terrestre y al medio. Este instrumento también sirve de catalizador entre lo real y lo ideal y es una síntesis de operaciones arquitectónicas, que mediante la comparación y/o oposición con los resultados previos del estudio arquetípico y de los Beatos, genera grandes grupos de características que se hallan entrelazadas en los proyectos paradisíacos. Gracias a estos documentos se puede concluir con una síntesis de características que comparten los proyectos paradisiacos, que en todo caso son esto, proyectos en plural. No existe la unicidad, ya que se infiere de este estudio que son, en conjunto, una forma de hacer ciertas arquitecturas. Tienen características medibles y reproducibles y unas condiciones tipológicas y de generación de campos que permiten producir muchos tipos de proyectos, todos ellos de tipología paradisíaca. ABSTRACT This thesis, Eden: Tale, Image and Project. The Concept of Terrestrial Paradise as a Generator of Architectures, is carried out with the objective of studying the relations between the idea of Eden or Paradise and architecture. In every case working from the three levels of representation, tale, image and project. On the approximation to the object of study, the investigation is centered on the tale itself, and in the same core of it, are found some implications that relate it with the world of mythology and archetype. These initial results consist of detecting that each one of the parts that form the edenic set; have previously been objects of cult in religions of a pagan or shamanic nature, since pre-historic times. Water, animals, earth and the grooves of the orchard, have all been objects of reverence since the dawn of time. Tracing the genealogy of these objects an archetypal type of analysis is taken on, which relates the revered objects with the subconscious and with the spontaneous manifestation of these in reality. These studies also provide results with spatial and architectonic implications, and it is concluded that more than an ideal or a concrete place, in myth or reality, what it definitely seems (and shows to be) is an architectonic typology, related in its formal and theoretical structure with that of the enclosed garden. The manifestation in image of these results, and the investigation itself, lead to reach for one of the most primitive set of images of the Garden of Eden, and that are in fact previous to the “invention” of the Hortus Conclusus as such. A collection of mozárabe representations of the Terrestrial Paradise as a concrete place on Earth. These are the mappaemundi included in the Codexes of the Beatos. By their study, the formal and theoretical structure of paradisal architectures is understood. Their importance in occidental culture makes these documents bring out their side as exoskeletons of the paradisal Project. Also, for their variety, they cast a great number of results of a spatial nature. The results released by the study of the edenic representations of the Beatos take the investigation to another moment and set of images within the history of architecture, where the radicality of the approaches to architecture, and the tabula rasa in relation to previous architectures make it necessary to invent new languages of approximation to the subject of project. This happens because of the globalizing tones that imply these architectures. The lapse of time referred to would be during the general practice of modern architecture. The object of calibration would be The Poem of the Right Angle, by Le Corbusier. The graphic document not only gives us the key of what flowed during that time when a new approximation to the surface of earth and to the environment was retrieved. This instrument also serves as a catalyst between real and ideal, and it is a synthesis of architectural operations that by comparison and/or opposition with the previous results of the archetypal study, and of the Beatos, generates large groups of characteristics that are intertwined in the paradisal project. Due to these documents we can conclude the investigation with a series of characteristics that share the paradisal projects, which in any case are this, projects, in plural. There is no uniqueness. From these findings, it can be inferred that a Paradisal Project is a way to undertake a project, and certain kinds of architecture. They are measurable and are underlaid by a consistent pattern, they also have typological conditions and of field generation, that make it possible to produce many kinds of projects, all of a paradisal typology.

Nepfix: on-demand cloud elastic simulation of networks of evolutionary processors

Una Red de Procesadores Evolutivos o NEP (por sus siglas en ingles), es un modelo computacional inspirado por el modelo evolutivo de las celulas, específicamente por las reglas de multiplicación de las mismas. Esta inspiración hace que el modelo sea una abstracción sintactica de la manipulation de information de las celulas. En particu¬lar, una NEP define una maquina de cómputo teorica capaz de resolver problemas NP completos de manera eficiente en tóerminos de tiempo. En la praóctica, se espera que las NEP simuladas en móaquinas computacionales convencionales puedan resolver prob¬lemas reales complejos (que requieran ser altamente escalables) a cambio de una alta complejidad espacial. En el modelo NEP, las cóelulas estóan representadas por palabras que codifican sus secuencias de ADN. Informalmente, en cualquier momento de cómputo del sistema, su estado evolutivo se describe como un coleccion de palabras, donde cada una de ellas representa una celula. Estos momentos fijos de evolucion se denominan configuraciones. De manera similar al modelo biologico, las palabras (celulas) mutan y se dividen en base a bio-operaciones sencillas, pero solo aquellas palabras aptas (como ocurre de forma parecida en proceso de selection natural) seran conservadas para la siguiente configuracióon. Una NEP como herramienta de computation, define una arquitectura paralela y distribuida de procesamiento simbolico, en otras palabras, una red de procesadores de lenguajes. Desde el momento en que el modelo fue propuesto a la comunidad científica en el año 2001, múltiples variantes se han desarrollado y sus propiedades respecto a la completitud computacional, eficiencia y universalidad han sido ampliamente estudiadas y demostradas. En la actualidad, por tanto, podemos considerar que el modelo teórico NEP se encuentra en el estadio de la madurez. La motivación principal de este Proyecto de Fin de Grado, es proponer una aproxi-mación práctica que permita dar un salto del modelo teórico NEP a una implantación real que permita su ejecucion en plataformas computacionales de alto rendimiento, con el fin de solucionar problemas complejos que demanda la sociedad actual. Hasta el momento, las herramientas desarrolladas para la simulation del modelo NEP, si bien correctas y con resultados satisfactorios, normalmente estón atadas a su entorno de ejecucion, ya sea el uso de hardware específico o implementaciones particulares de un problema. En este contexto, el propósito fundamental de este trabajo es el desarrollo de Nepfix, una herramienta generica y extensible para la ejecucion de cualquier algo¬ritmo de un modelo NEP (o alguna de sus variantes), ya sea de forma local, como una aplicación tradicional, o distribuida utilizando los servicios de la nube. Nepfix es una aplicacion software desarrollada durante 7 meses y que actualmente se encuentra en su segunda iteration, una vez abandonada la fase de prototipo. Nepfix ha sido disenada como una aplicacion modular escrita en Java 8 y autocontenida, es decir, no requiere de un entorno de ejecucion específico (cualquier maquina virtual de Java es un contenedor vólido). Nepfix contiene dos componentes o móodulos. El primer móodulo corresponde a la ejecución de una NEP y es por lo tanto, el simulador. Para su desarrollo, se ha tenido en cuenta el estado actual del modelo, es decir, las definiciones de los procesadores y filtros mas comunes que conforman la familia del modelo NEP. Adicionalmente, este componente ofrece flexibilidad en la ejecucion, pudiendo ampliar las capacidades del simulador sin modificar Nepfix, usando para ello un lenguaje de scripting. Dentro del desarrollo de este componente, tambióen se ha definido un estóandar de representacióon del modelo NEP basado en el formato JSON y se propone una forma de representation y codificación de las palabras, necesaria para la comunicación entre servidores. Adicional-mente, una característica importante de este componente, es que se puede considerar una aplicacion aislada y por tanto, la estrategia de distribution y ejecución son total-mente independientes. El segundo moódulo, corresponde a la distribucióon de Nepfix en la nube. Este de-sarrollo es el resultado de un proceso de i+D, que tiene una componente científica considerable. Vale la pena resaltar el desarrollo de este modulo no solo por los resul-tados prócticos esperados, sino por el proceso de investigation que se se debe abordar con esta nueva perspectiva para la ejecución de sistemas de computación natural. La principal característica de las aplicaciones que se ejecutan en la nube es que son gestionadas por la plataforma y normalmente se encapsulan en un contenedor. En el caso de Nepfix, este contenedor es una aplicacion Spring que utiliza el protocolo HTTP o AMQP para comunicarse con el resto de instancias. Como valor añadido, Nepfix aborda dos perspectivas de implementation distintas (que han sido desarrolladas en dos iteraciones diferentes) del modelo de distribution y ejecucion, que tienen un impacto muy significativo en las capacidades y restricciones del simulador. En concreto, la primera iteration utiliza un modelo de ejecucion asincrono. En esta perspectiva asincrona, los componentes de la red NEP (procesadores y filtros) son considerados como elementos reactivos a la necesidad de procesar una palabra. Esta implementation es una optimization de una topologia comun en el modelo NEP que permite utilizar herramientas de la nube para lograr un escalado transparente (en lo ref¬erente al balance de carga entre procesadores) pero produce efectos no deseados como indeterminacion en el orden de los resultados o imposibilidad de distribuir eficiente-mente redes fuertemente interconectadas. Por otro lado, la segunda iteration corresponde al modelo de ejecucion sincrono. Los elementos de una red NEP siguen un ciclo inicio-computo-sincronizacion hasta que el problema se ha resuelto. Esta perspectiva sincrona representa fielmente al modelo teórico NEP pero el proceso de sincronizacion es costoso y requiere de infraestructura adicional. En concreto, se requiere un servidor de colas de mensajes RabbitMQ. Sin embargo, en esta perspectiva los beneficios para problemas suficientemente grandes superan a los inconvenientes, ya que la distribuciín es inmediata (no hay restricciones), aunque el proceso de escalado no es trivial. En definitiva, el concepto de Nepfix como marco computacional se puede considerar satisfactorio: la tecnología es viable y los primeros resultados confirman que las carac-terísticas que se buscaban originalmente se han conseguido. Muchos frentes quedan abiertos para futuras investigaciones. En este documento se proponen algunas aproxi-maciones a la solucion de los problemas identificados como la recuperacion de errores y la division dinamica de una NEP en diferentes subdominios. Por otra parte, otros prob-lemas, lejos del alcance de este proyecto, quedan abiertos a un futuro desarrollo como por ejemplo, la estandarización de la representación de las palabras y optimizaciones en la ejecucion del modelo síncrono. Finalmente, algunos resultados preliminares de este Proyecto de Fin de Grado han sido presentados recientemente en formato de artículo científico en la "International Work-Conference on Artificial Neural Networks (IWANN)-2015" y publicados en "Ad-vances in Computational Intelligence" volumen 9094 de "Lecture Notes in Computer Science" de Springer International Publishing. Lo anterior, es una confirmation de que este trabajo mas que un Proyecto de Fin de Grado, es solo el inicio de un trabajo que puede tener mayor repercusion en la comunidad científica. Abstract Network of Evolutionary Processors -NEP is a computational model inspired by the evolution of cell populations, which might model some properties of evolving cell communities at the syntactical level. NEP defines theoretical computing devices able to solve NP complete problems in an efficient manner. In this model, cells are represented by words which encode their DNA sequences. Informally, at any moment of time, the evolutionary system is described by a collection of words, where each word represents one cell. Cells belong to species and their community evolves according to mutations and division which are defined by operations on words. Only those cells are accepted as surviving (correct) ones which are represented by a word in a given set of words, called the genotype space of the species. This feature is analogous with the natural process of evolution. Formally, NEP is based on an architecture for parallel and distributed processing, in other words, a network of language processors. Since the date when NEP was pro¬posed, several extensions and variants have appeared engendering a new set of models named Networks of Bio-inspired Processors (NBP). During this time, several works have proved the computational power of NBP. Specifically, their efficiency, universality, and computational completeness have been thoroughly investigated. Therefore, we can say that the NEP model has reached its maturity. The main motivation for this End of Grade project (EOG project in short) is to propose a practical approximation that allows to close the gap between theoretical NEP model and a practical implementation in high performing computational platforms in order to solve some of high the high complexity problems society requires today. Up until now tools developed to simulate NEPs, while correct and successful, are usu¬ally tightly coupled to the execution environment, using specific software frameworks (Hadoop) or direct hardware usage (GPUs). Within this context the main purpose of this work is the development of Nepfix, a generic and extensible tool that aims to execute algorithms based on NEP model and compatible variants in a local way, similar to a traditional application or in a distributed cloud environment. Nepfix as an application was developed during a 7 month cycle and is undergoing its second iteration once the prototype period was abandoned. Nepfix is designed as a modular self-contained application written in Java 8, that is, no additional external dependencies are required and it does not rely on an specific execution environment, any JVM is a valid container. Nepfix is made of two components or modules. The first module corresponds to the NEP execution and therefore simulation. During the development the current state of the theoretical model was used as a reference including most common filters and processors. Additionally extensibility is provided by the use of Python as a scripting language to run custom logic. Along with the simulation a definition language for NEP has been defined based on JSON as well as a mechanisms to represent words and their possible manipulations. NEP simulator is isolated from distribution and as mentioned before different applications that include it as a dependency are possible, the distribution of NEPs is an example of this. The second module corresponds to executing Nepfix in the cloud. The development carried a heavy R&D process since this front was not explored by other research groups until now. It's important to point out that the development of this module is not focused on results at this point in time, instead we focus on feasibility and discovery of this new perspective to execute natural computing systems and NEPs specifically. The main properties of cloud applications is that they are managed by the platform and are encapsulated in a container. For Nepfix a Spring application becomes the container and the HTTP or AMQP protocols are used for communication with the rest of the instances. Different execution perspectives were studied, namely asynchronous and synchronous models were developed for solving different kind of problems using NEPs. Different limitations and restrictions manifest in both models and are explored in detail in the respective chapters. In conclusion we can consider that Nepfix as a computational framework is suc-cessful: Cloud technology is ready for the challenge and the first results reassure that the properties Nepfix project pursued were met. Many investigation branches are left open for future investigations. In this EOG implementation guidelines are proposed for some of them like error recovery or dynamic NEP splitting. On the other hand other interesting problems that were not in the scope of this project were identified during development like word representation standardization or NEP model optimizations. As a confirmation that the results of this work can be useful to the scientific com-munity a preliminary version of this project was published in The International Work- Conference on Artificial Neural Networks (IWANN) in May 2015. Development has not stopped since that point and while Nepfix in it's current state can not be consid¬ered a final product the most relevant ideas, possible problems and solutions that were produced during the seven months development cycle are worthy to be gathered and presented giving a meaning to this EOG work.

The segmental approximation in multijunction solar cells

The segmental approach has been considered to analyze dark and light I-V curves. The photovoltaic (PV) dependence of the open-circuit voltage (Voc), the maximum power point voltage (Vm), the efficiency (?) on the photogenerated current (Jg), or on the sunlight concentration ratio (X), are analyzed, as well as other photovoltaic characteristics of multijunction solar cells. The characteristics being analyzed are split into monoexponential (linear in the semilogarithmic scale) portions, each of which is characterized by a definite value of the ideality factor A and preexponential current J0. The monoexponentiality ensures advantages, since at many steps of the analysis, one can use the analytical dependences instead of numerical methods. In this work, an experimental procedure for obtaining the necessary parameters has been proposed, and an analysis of GaInP/GaInAs/Ge triple-junction solar cell characteristics has been carried out. It has been shown that up to the sunlight concentration ratios, at which the efficiency maximum is achieved, the results of calculation of dark and light I-V curves by the segmental method fit well with the experimental data. An important consequence of this work is the feasibility of acquiring the resistanceless dark and light I-V curves, which can be used for obtaining the I-V curves characterizing the losses in the transport part of a solar cell.