Methodology for the improvement integrated magnetics design, and solutions obtained applying it

Technology offered by Carlos III of Madrid University, Spain. It allows increasing the optimization capability of the design of integrated magnetic components, by means of the extension of the degrees of freedom in the design procedure. It is possible to simplify the design, improved performance and reduce size and costs of the component. Custom made solutions based in this method, applied to electric systems or power electronics, are offered

Yet another approach to the Gough-Stewart platform forward kinematics

© 20xx IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.The forward kinematics of the Gough-Stewart platform, and their simplified versions in which some leg endpoints coalesce, has been typically solved using variable elimination methods. In this paper, we cast doubts on whether this is the easiest way to solve the problem. We will see how the indirect approach in which the length of some extra virtual legs is first computed leads to important simplifications. In particular, we provide a procedure to solve 30 out of 34 possible topologies for a Gough-Stewart platform without variable elimination.Peer ReviewedPostprint (author's final draft

Path planning for active tensegrity structures

This paper presents a path planning method for actuated tensegrity structures with quasi-static motion. The valid configurations for such structures lay on an equilibrium manifold, which is implicitly defined by a set of kinematic and static constraints. The exploration of this manifold is difficult with standard methods due to the lack of a global parameterization. Thus, this paper proposes the use of techniques with roots in differential geometry to define an atlas, i.e., a set of coordinated local parameterizations of the equilibrium manifold. This atlas is exploited to define a rapidly-exploring random tree, which efficiently finds valid paths between configurations. However, these paths are typically long and jerky and, therefore, this paper also introduces a procedure to reduce their control effort. A variety of test cases are presented to empirically evaluate the proposed method. (C) 2015 Elsevier Ltd. All rights reserved.Peer ReviewedPostprint (author's final draft

A bayesian approach to simultaneously recover camera pose and non-rigid shape from monocular images

© . This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/In this paper we bring the tools of the Simultaneous Localization and Map Building (SLAM) problem from a rigid to a deformable domain and use them to simultaneously recover the 3D shape of non-rigid surfaces and the sequence of poses of a moving camera. Under the assumption that the surface shape may be represented as a weighted sum of deformation modes, we show that the problem of estimating the modal weights along with the camera poses, can be probabilistically formulated as a maximum a posteriori estimate and solved using an iterative least squares optimization. In addition, the probabilistic formulation we propose is very general and allows introducing different constraints without requiring any extra complexity. As a proof of concept, we show that local inextensibility constraints that prevent the surface from stretching can be easily integrated. An extensive evaluation on synthetic and real data, demonstrates that our method has several advantages over current non-rigid shape from motion approaches. In particular, we show that our solution is robust to large amounts of noise and outliers and that it does not need to track points over the whole sequence nor to use an initialization close from the ground truth.Peer ReviewedPostprint (author's final draft

Desarrollo de un sistema de análisis de medidas de internet procedentes de repositorios abiertos de datos

Internet se ha convertido en un elemento esencial para la realización de un amplio abanico de tareas cotidianas. Por ello, caracterizar las prestaciones de las conexiones domésticas a Internet es un problema que preocupa tanto a usuarios como instituciones públicas y empresas proveedoras de servicios sobre esta infraestructura de comunicaciones. Además, numerosos resultados indican que estas prestaciones se deben medir desde el emplazamiento de los usuarios finales, debido a las diferentes características de los accesos domésticos frente a los propios de centros de investigación o empresas. Esta situación ocasiona que, para poder realizar estudios en profundidad sobre el funcionamiento de Internet, sea necesario considerar un gran volumen de datos, con las dificultades de análisis que ello conlleva. En este contexto, este trabajo fin de grado describe el desarrollo de un sistema de análisis de medidas de Internet. Este sistema facilita la consulta y visualización de indicadores clave de prestaciones que indica cómo se comportan las conexiones a Internet, permitiendo evaluar el efecto de factores tales como la localización geográfica, momento del día, el tipo de conexión o el Sistema Autónomo del cliente. El sistema de análisis propuesto se divide en cuatro bloques funcionales, dedicados respectivamente a la obtención de las medidas; a la limpieza de los datos e incorporación de información de geolocalización; a la indexación y persistencia de los registros consolidados; y a la consulta y visualización de dichos registros. De este modo, define un flujo de datos completo que facilita la extracción de conclusiones útiles para la gestión y caracterización de las prestaciones de las infraestructuras de telecomunicaciones desde usuarios finales. Para mostrar el funcionamiento de este sistema, capaz de obtener datos a partir de fuentes abiertas, se realizarán una serie de casos de estudio sobre las medidas obtenidas durante los primeros meses del experimento NDT, incluido en la plataforma M-Lab de Google. Estos casos de estudio muestran la solución desarrollada, permitiendo visualizar y analizar un gran volumen de datos (más de 200000 experimentos) procedentes de una amplia variedad de localizaciones geográficas mientras se incorporan al sistemaInternet has become an essential element for the performance of a wide range of daily tasks. Thus, the characterizing of the performance of domestic connectivity to the Internet is a problem that concerns users, public institutions and companies that provide services that make use of this communications infrastructure. Besides, many results show that performance indicators must be measured from the location of the end users, as a consequence of the differences among domestic connections and those present in research centers or companies. Coherently, a comprehensive study of the operation of the Internet requires considering a humongous amount of data, with the technical challenges that follow from such an analysis. In this context, this bachelor thesis describes the development of an Internet measurements analysis system able to alleviate these matters. This system makes easier the query and visualization of key performance indicators that show how Internet connections behave. In such manner, it allows evaluating the effect of several factors, such as geographical location, time of day, connection type or the client Autonomous System. The proposed system is divided in four functional blocks, devoted to the data collection, data cleaning and information about location, data indexing and the query and visualization of records, respectively. In this way, it provides a complete data flow that makes possible the extraction of useful conclusions for the management and characterization of the performance of telecommunication infraestructures from the standpoint of end users. In order to show the operation of this system, which is also capable of obtaining data from open data sources, it will be exploited to conduct several case studies about the measurements obtained during the first months of the NDT experiment, included in the MLab platform of Google. These case studies show how the developed solution is suitable for visualizing and analyzing a large volume of data (more than 200,000 experiments) from a wide variety of geographical locations as they are inserted in the syste

Fundamental studies of vibrated fluidized beds

Mención Internacional en el título de doctorLa fluidización es un proceso ampliamente utilizado en las industrias química, energética y de tratamiento de materiales debido a su buen rendimiento en el mezclado de sólidos y a su buena eficiencia de contacto, tanto sólido-sólido como gas-sólido. Entre las operaciones que hacen uso de lechos fluidizados se encuentran, por ejemplo, el craqueo catalítico (FCC), gasificación, combustión de combustibles sólidos, síntesis de Fischer-Tropsch, secado, granulación y recubrimiento de partículas. Sin embargo, la facilidad con la que las partículas fluidizan puede verse afectada por diversos factores. Por ejemplo, las partículas finas tienden a aglomerarse, lo que puede llegar a defluidizar el lecho o a formar caminos preferentes de gas en el mismo. Se han empleado múltiples estrategias para eliminar la aglomeración y mejorar la homogeneidad de fluidización. Entre estas estrategias se encuentra la vibración de un lecho fluidizado convencional, la cual es una tecnología prometedora consistente en la introducción de energía cinética en el sistema mediante la vibración mecánica de la vasija del lecho. Esta vibración proporciona la energía necesaria para romper los enlaces entre partículas, prevenir su aglomeración y evitar la canalización del gas en el lecho. A pesar de sus ventajas, la vibración introduce complejidades en la dinámica del lecho que están aún lejos de ser plenamente comprendidas. El conocimiento de estos fenómenos físicos complejos derivados de la vibración de un lecho fluidizado podría ser utilizado para la mejora del diseño y control de los lechos fluidizados vibrantes existentes, así como para aumentar su rango de operación en nuevas aplicaciones. Por todo lo anterior, un estudio de carácter fundamental del efecto de la vibración en el movimiento de la fase densa del lecho y de las burbujas presentes en el sistema es de suma importancia para entender la dinámica de este tipo de dispositivos. Este es el objetivo de la presente tesis doctoral, cuya estructura y resultados principales se indican en los párrafos siguientes.../ ... En resumen, la presente tesis doctoral revela, tanto experimentalmente como con la ayuda de modelos numéricos, que (i) la compresibilidad del gas afecta a las oscilaciones de la fase densa de un lecho fluidizado vibrado, (ii) la presencia ondas de compresión y de expansión de sólidos y de gas causadas por la la vibración de la vasija domina el comportamiento de burbujas aisladas en el lecho, (iii) estas ondas se generan en la base del lecho y viajan en dirección ascendente modificando el comportamiento medio y oscilatorio de las propiedades de las burbujas en función de la distancia al distribuidor, (iv) esto es aplicable a lechos operados en régimen burbujeante en los que existe una continua interacción entre burbujas y (v) la vibración introduce un grado extra de libertad que permite controlar la segregación y modificar los patrones de movimiento de las partículas en el lecho.Fluidization is a process extensively used in the energy, chemical and materials processing industries owing to the good performance in solid mixing and the high solid-solid and gassolid contact efficiencies it provides. Among the operations making use of gas fluidized beds are fluid catalytic cracking (FCC), gasification, combustion of solid fuels, Fischer- Tropsch synthesis, drying, granulation and coating. However, the ease with which particles fluidize may be affected by diverse factors. For example, fine particles tend to agglomerate, which can end up defluidizing the bed. Several strategies have been employed to eliminate agglomeration and improve the fluidization homogeneity. Among these strategies, vibration of a conventional fluidized bed is a promising technology consisting in introducing kinetic energy to the system by mechanical vibration of the bed vessel. Vibration provides the necessary energy to break interparticle bonds and prevent agglomeration and gas channeling. Despite its advantages, vibration introduces complexities in the dynamics of the bed that are still far from being fully understood. Knowledge of these complex physical phenomena arising from vibration of a fluidized bed could be used to improve design and control of the existing vibrated beds and to increase their range of operation to new applications. Therefore, a fundamental study of the effect of vibration on the bulk motion and the bubbles rising in a fluidized bed is paramount to understand the dynamics in this kind of gas-solids systems. This is the aim of the present dissertation, whose structure and main results are described in the following paragraphs ... / ... In summary, the present PhD thesis principally reveals, both experimentally and with the aid of numerical models, that (i) gas compressibility affects the oscillations of the bed bulk in vibrated fluidized beds, (ii) the presence of compression and expansion waves of solids and gas caused by the vibration of the bed vessel commands the behavior of isolated bubbles in the bed, (iii) these waves are generated at the base of the bed and travel upwards modifying the mean and the oscillatory behavior of bubble characteristics as a function of the distance to the distributor, (iv) this is also applicable to beds in bubbling regime with multiple interacting bubbles and (v) vibration introduces an extra degree of freedom to control segregation and modify the patterns of particle motion in the bed.Programa Oficial de Doctorado en Ingeniería Mecánica y de Organización IndustrialPresidente: Miguel Alejandro Menéndez Sastre.- Secretario: David Jordi Pallarés I Tella.- Vocal: J. Ruud Van Omme

Beam impact tests of a prototype target for the beam dump facility at CERN: Experimental setup and preliminary analysis of the online results

The beam dump facility (BDF) is a project for a new facility at CERN dedicated to high intensity beam dump and fixed target experiments. Currently in its design phase, the first aim of the facility is to search for light dark matter and hidden sector models with the Search for Hidden Particles (SHiP) experiment. At the core of the facility sits a dense target/dump, whose function is to absorb safely the 400 GeV/c Super Proton Synchrotron (SPS) beam and to maximize the production of charm and beauty mesons. An average power of 300 kW will be deposited on the target, which will be subjected to unprecedented conditions in terms of temperature, structural loads and irradiation. In order to provide a representative validation of the target design, a prototype target has been designed, manufactured, and tested under the SPS fixed-target proton beam during 2018, up to an average beam power of 50 kW, corresponding to 350 kJ per pulse. The present contribution details the target prototype design and experimental setup, as well as a first evaluation of the measurements performed during beam irradiation. The analysis of the collected data suggests that a representative reproduction of the operational conditions of the beam dump facility target was achieved during the prototype tests, which will be complemented by a postirradiation examination campaign during 2020. © 2019 authors. Published by the American Physical Society

A randomized kinodynamic planner for closed-chain robotic systems

Kinodynamic RRT planners are effective tools for finding feasible trajectories in many classes of robotic systems. However, they are hard to apply to systems with closed-kinematic chains, like parallel robots, cooperating arms manipulating an object, or legged robots keeping their feet in contact with the environ- ment. The state space of such systems is an implicitly-defined manifold, which complicates the design of the sampling and steering procedures, and leads to trajectories that drift away from the manifold when standard integration methods are used. To address these issues, this report presents a kinodynamic RRT planner that constructs an atlas of the state space incrementally, and uses this atlas to both generate ran- dom states, and to dynamically steer the system towards such states. The steering method is based on computing linear quadratic regulators from the atlas charts, which greatly increases the planner efficiency in comparison to the standard method that simulates random actions. The atlas also allows the integration of the equations of motion as a differential equation on the state space manifold, which eliminates any drift from such manifold and thus results in accurate trajectories. To the best of our knowledge, this is the first kinodynamic planner that explicitly takes closed kinematic chains into account. We illustrate the performance of the approach in significantly complex tasks, including planar and spatial robots that have to lift or throw a load at a given velocity using torque-limited actuators.Peer ReviewedPreprin

Closure polynomials for strips of tetrahedra

The final publication is available at link.springer.comA tetrahedral strip is a tetrahedron-tetrahedron truss where any tetrahedron has two neighbors except those in the extremes which have only one. Unless any of the tetrahedra degenerate, such a truss is rigid. In this case, if the distance between the strip endpoints is imposed, any rod length in the truss is constrained by all the others to attain discrete values. In this paper, it is shown how to characterize these values as the roots of a closure polynomial whose derivation requires surprisingly no other tools than elementary algebraic manipulations. As an application of this result, the forward kinematics of two parallel platforms with closure polynomials of degree 16 and 12 is straightforwardly solved.Peer ReviewedPostprint (author's final draft