Cholesterol granuloma of the petrous apex: benefit of computer-aided surgery

The following is an analysis of the role of computer aided surgery by infralabyrinthine-subcochlear approach to the petrous apex for cholesterol granulomas with hearing preservation. In a retrospective case review from 1996 to 2008 six patients were analysed in our tertiary referral centre, otorhinolaryngology outpatient clinic. Excellent intraoperative localisation of the carotid artery, facial nerve and the entrance into the cholesterol cyst of the bone by means of the navigation system was seen. Additionally, the operation time decreased from an initial 4 h down to 2 h. The application of computer-aided surgery allows intraoperative monitoring of the position of the tip of the microsurgical instruments in case of a rare disease and in the delicate area of the petrous apex giving a high security level.

DEVELOPMENT OF THE ECOCAR 3 PROPOSAL AND GUIDELINES FOR MODELING AND DESIGN IN YEAR ONE OF ECOCAR 3

This report summarizes the work done for the Vehicle Powertrain Modeling and Design Problem Proposal portion of the EcoCAR3 proposal as specified in the Request for Proposal from Argonne National Laboratory. The results of the modeling exercises presented in the proposal showed that: An average conventional vehicle powered by a combustion engine could not meet the energy consumption target when the engine was sized to meet the acceleration target, due the relatively low thermal efficiency of the spark ignition engine. A battery electric vehicle could not meet the required range target of 320 km while keeping the vehicle weight below the gross vehicle weight rating of 2000 kg. This was due to the low energy density of the batteries which necessitated a large, and heavy, battery pack to provide enough energy to meet the range target. A series hybrid electric vehicle has the potential to meet the acceleration and energy consumption parameters when the components are optimally sized. A parallel hybrid electric vehicle has less energy conversion losses than a series hybrid electric vehicle which results in greater overall efficiency, lower energy consumption, and less emissions. For EcoCAR3, Michigan Tech proposes to develop a plug-in parallel hybrid vehicle (PPHEV) powered by a small Diesel engine operating on B20 Bio-Diesel fuel. This architecture was chosen over other options due to its compact design, lower cost, and its ability to provide performance levels and energy efficiency that meet or exceed the design targets. While this powertrain configuration requires a more complex control system and strategy than others, the student engineering team at Michigan Tech has significant recent experience with this architecture and has confidence that it will perform well in the events planned for the EcoCAR3 competition.

Differential diagnosis of CT focal liver lesions using texture features, feature selection and ensemble driven classifiers

The aim of the present study is to define an optimally performing computer-aided diagnosis (CAD) architecture for the classification of liver tissue from non-enhanced computed tomography (CT) images into normal liver (C1), hepatic cyst (C2), hemangioma (C3), and hepatocellular carcinoma (C4). To this end, various CAD architectures, based on texture features and ensembles of classifiers (ECs), are comparatively assessed.

Dentinhaftkraft zweier neuer CAD/CAM-Materialien in Abhängigkeit verschiedener adhäsiver Zementsysteme

Zielsetzung: Ziel der Studie war die Bestimmung der Dentinhaftkraft von zwei so-genannten Hybridmaterialien für computer-aided design/computer-aided manufacturing (CAD/CAM) Restaurationen unter Anwendung von fünf verschiedenen Zementen vor und nach sechsmonatiger Lagerung. Materialien und Methoden: Aus extrahierten menschlichen Molaren wurden 300 Dentinprobekörper hergestellt (n=15 pro Gruppe; 10 Gruppen (2 Hybridkeramiken, 5 Zemente) je nach 24 h/nach sechsmonatiger Lagerung). Aus Hybridkeramikblöcken von Lava Ultimate (3M ESPE) und VITA ENAMIC (VITA Zahnfabrik) wurden Zylinder hergestellt, welche standardisiert aufgeraut wurden. Anschliessend wurden die Hybrid-keramikzylinder mit einem der folgenden fünf Zemente auf die Dentinprobekörper zementiert: mit den Kompositzementen RelyX Ultimate (3M ESPE), PANAVIA F2.0 (Kuraray), Variolink II (Ivoclar Vivadent), els cem (Saremco Dental AG) oder als Negativkontrollgruppe mit dem kunststoffmodifizierten Glasionomerzement Ketac Cem Plus (3M ESPE). Die Dentinhaftkraft der Hybridkeramikzylinder wurde einerseits nach 24 h und andererseits nach sechsmonatiger Lagerung via Scherkrafttest bestimmt. Nach dem Scherkrafttest wurde das Bruchmuster unter einem Lichtmikroskop bei 40-facher Vergrösserung beurteilt. Die Dentinhaftkraftwerte wurden mittels nichtparametrischer ANOVA gefolgt von exakten Wilcoxon Rangsummen-Tests statistisch analysiert (α=0,05). Die Beurteilung des Bruchmusters wurde deskriptiv ausgewertet. Resultate: Für die Hybridkeramik Lava Ultimate und nach 24 h erzielten die Kompositzemente RelyX Ultimate und Variolink II die höchsten Dentinhaftkraftwerte. Die Dentinhaftkraftwerte von RelyX Ultimate und Variolink II unterschieden sich nicht signifikant. Die Dentinhaftkraftwerte von PANAVIA F2.0 unterschieden sich ebenfalls nicht signifikant von denjenigen von RelyX Ultimate, waren jedoch signifikant tiefer als diejenigen von Variolink II. Unter allen Kompositzementen erzielte els cem die tiefsten Dentinhaftkraftwerte. Nach sechsmonatiger Lagerung waren die Dentinhaftkraftwerte für RelyX Ultimate die höchsten, gefolgt von Variolink II, von els cem und anschliessend von PANAVIA F2.0, welcher nach sechsmonatiger Lagerung die tiefsten Dentinhaftkraftwerte der Kompositzemente zeigte. Der kunststoffmodifizierte Glasionomerzement Ketac Cem Plus zeigte sowohl nach 24 h als auch nach sechsmonatiger Lagerung die tiefsten Dentinhaftkraftwerte. Für VITA ENAMIC war die Reihenfolge der Zemente nach Dentinhaftkraft nach 24 h ähnlich wie diejenige nach sechsmonatiger Lagerung: Die Dentinhaftkraft war für RelyX Ultimate und Variolink II am höchsten, gefolgt von PANAVIA F2.0, von els cem und schlussendlich von Ketac Cem Plus mit den tiefsten Dentinhaftkraftwerten. Nach 24 h und für alle fünf Zemente unterschieden sich die Dentinhaftkraftwerte zwischen Lava Ultimate und VITA ENAMIC nicht signifikant. Nach sechsmonatiger Lagerung unterschieden sich die Dentinhaftkraftwerte zwischen Lava Ultimate und VITA ENAMIC ebenfalls nicht signifikant für RelyX Ultimate und els cem im Gegensatz zu den Dentinhaftkraftwerten von PANAVIA F2.0, Variolink II und Ketac Cem Plus, welche signifikant tiefer waren für Lava Ultimate als für VITA ENAMIC. Das häufigste Bruch-muster war für Lava Ultimate nach 24 h und für VITA ENAMIC sowohl nach 24 h als auch nach sechsmonatiger Lagerung adhäsiv zwischen Dentin und Zement. Nach sechs-monatiger Lagerung war für Lava Ultimate das häufigste Bruchmuster tendenziell gemischte Brüche. Schlussfolgerung: Basierend auf den Resultaten kann gesagt werden, dass für beide Hybridkeramiken sowohl RelyX Ultimate als auch Variolink II empfohlen werden können. PANAVIA F2.0 kann für VITA ENAMIC empfohlen werden, für Lava Ultimate allerdings weniger, da die Dentinhaftkraft nach sechsmonatiger Lagerung abnahm. Von einer konventionellen (allerdings nicht indizierten und in dieser Studie experimentellen) Zemen-tierung der beiden Hybridkeramiken mit dem kunststoffmodifizierten Glasionomerzement Ketac Cem Plus muss abgeraten werden.

Einfluss von Politursystemen auf Oberflächenrauigkeit und mechanische Eigenschaften von CAD/CAM-Materialien

Zielsetzung: Das Ziel dieser Studie war, den Einfluss von drei Politursystemen auf die Oberflächenrauigkeit von verschiedenen Materialien für computer-aided design/computer-aided manufacturing (CAD/CAM) Restaurationen mittels Profilometrie sowie die mikromechanischen Eigenschaften der Materialien mittels Mikrohärtemessgerät zu analysieren. Materialien und Methoden: Von dem CAD/CAM-Kompositmaterial Paradigm MZ100 (3M ESPE), der CAD/CAM-Feldspatkeramik VITABLOCS Mark II (VITA Zahnfabrik) und den CAD/CAM-Hybridmaterialien Lava Ultimate (3M ESPE), VITA ENAMIC (VITA Zahnfabrik) und AMBARINO High-Class (Creamed) wurden je 60 Prüfkörper zugeschnitten, gekennzeichnet und standardisiert aufgerauht. Die standardisierte Aufrauhung wurde mit Baseline-Rauigkeitsmessungen überprüft (Ra und Rz; µm). Die Prüfkörper wurden mit einem von drei Politursystemen poliert (n=20 pro CAD/CAM-Material): 1) Sof-Lex Scheiben (Disc-System, 3 Politurschritte: medium, fein und superfein; 3M ESPE), 2) VITA Polishing Set Clinical (Silikonpolitursystem, 2 Politurschritte: medium und fein; VITA Zahnfabrik) oder 3) KENDA Nobilis (Silikonpolierer, 1 Politurschritt (universal); KENDA Dental). Nach Politur der Prüfkörper wurden Ra und Rz sowie die mikromechanischen Eigenschaften Oberflächenhärte (VHN; Vickers Härte) und Elastizitätsmodul (EM; GPa) gemessen. In den darauf folgenden sechs Monaten wurden die Prüfkörper in Leitungswasser gelagert und insgesamt sechs Mal einem maschinellem Zahnbürsten zugeführt. Anschliessend wurden erneut Ra und Rz sowie VHN und EM gemessen. Ra-, Rz-, VHN- und EM-Werte wurden mittels nichtparametrischer ANOVA global analysiert und die p-Werte mittels Bonferroni-Holm Korrektur für multiples Testen korrigiert. Als post-hoc Tests wurden Kruskal-Wallis-Tests sowie exakte Wilcoxon Rangsummen-Tests verwendet und die p-Werte wurden nicht korrigiert. Das Signifikanzniveau wurde auf α=0,05 festgelegt. Resultate: Für alle drei CAD/CAM-Hybridmaterialien ergaben Sof-Lex Scheiben nach der Politur die tiefste Oberflächenrauigkeit (d. h. die tiefsten Ra- und Rz-Werte), gefolgt von KENDA Nobilis und von dem VITA Polishing Set Clinical. Bei dem CAD/CAM-Kompositmaterial sowie bei der CAD/CAM-Feldspatkeramik ergaben Sof-Lex Scheiben und KENDA Nobilis ähnliche Resultate, gefolgt von dem VITA Polishing Set Clinical. Bei einigen CAD/CAM-Materialien zeigten sich – zum Teil in Abhängigkeit des Politursystems – nach maschinellem Zahnbürsten und Lagerung signifikant höhere Ra- und Rz-Werte. Die CAD/CAM-Materialien zeigten unabhängig des Politursystems und der Lagerung signifikant verschiedene VHN- und EM-Werte. Bei einigen CAD/CAM-Materialien zeigten sich – zum Teil ebenfalls in Abhängigkeit des Politursystems – nach maschinellem Zahn-bürsten und Lagerung signifikant tiefere VHN- und EM-Werte. Schlussfolgerungen: Die Wahl des Politursystems beeinflusste die Oberflächenrauigkeit der CAD/CAM-Materialien markant, wobei Sof-Lex Scheiben insgesamt die besten Politurresultate zeigten, gefolgt von dem Silikonpolierer KENDA Nobilis. Von der Verwendung des Silikonpolitursystems VITA Polishing Set Clinical muss eher abgeraten werden. Das CAD/CAM-Kompositmaterial Paradigm MZ100 und die CAD/CAM-Hybridmaterialien Lava Ultimate und AMBARINO High-Class als weichere und elastischere Materialien liessen sich insgesamt besser polieren, waren aber bezüglich mechanischer Eigenschaften anfälliger auf Lagerung als die härtere CAD/CAM-Feldspatkeramik VITABLOCS Mark II und das CAD/CAM-Hybridmaterial VITA ENAMIC.

The impact of a computer based adult literacy program on literacy and numeracy : evidence from India

With over 700 million illiterate adults in the world, many governments have implemented adult literacy programs across the world, although typically with low rates of success partly because the quality of teaching is low. One solution may lie in the standardization of teaching provided by computer-aided instruction. We present the first rigorous evidence of the effectiveness of a computer-based adult literacy program. A randomized control trial study of TARA Akshar Plus, an Indian adult literacy program, was implemented in the state of Uttar Pradesh in India. We find large, significant impacts of this computer-aided program on literacy and numeracy outcomes. We compare the improvement in learning to that of other traditional adult literacy programs and conclude that TARA Akshar Plus is effective in increasing literacy and numeracy for illiterate adult women.

Development of Efficient Techniques for the Analysis and Design of Antennas in Dual-Reflectarray Configuration

This thesis contributes to the analysis and design of printed reflectarray antennas. The main part of the work is focused on the analysis of dual offset antennas comprising two reflectarray surfaces, one of them acts as sub-reflector and the second one acts as mainreflector. These configurations introduce additional complexity in several aspects respect to conventional dual offset reflectors, however they present a lot of degrees of freedom that can be used to improve the electrical performance of the antenna. The thesis is organized in four parts: the development of an analysis technique for dualreflectarray antennas, a preliminary validation of such methodology using equivalent reflector systems as reference antennas, a more rigorous validation of the software tool by manufacturing and testing a dual-reflectarray antenna demonstrator and the practical design of dual-reflectarray systems for some applications that show the potential of these kind of configurations to scan the beam and to generate contoured beams. In the first part, a general tool has been implemented to analyze high gain antennas which are constructed of two flat reflectarray structures. The classic reflectarray analysis based on MoM under local periodicity assumption is used for both sub and main reflectarrays, taking into account the incident angle on each reflectarray element. The incident field on the main reflectarray is computed taking into account the field radiated by all the elements on the sub-reflectarray.. Two approaches have been developed, one which employs a simple approximation to reduce the computer run time, and the other which does not, but offers in many cases, improved accuracy. The approximation is based on computing the reflected field on each element on the main reflectarray only once for all the fields radiated by the sub-reflectarray elements, assuming that the response will be the same because the only difference is a small variation on the angle of incidence. This approximation is very accurate when the reflectarray elements on the main reflectarray show a relatively small sensitivity to the angle of incidence. An extension of the analysis technique has been implemented to study dual-reflectarray antennas comprising a main reflectarray printed on a parabolic surface, or in general in a curved surface. In many applications of dual-reflectarray configurations, the reflectarray elements are in the near field of the feed-horn. To consider the near field radiated by the horn, the incident field on each reflectarray element is computed using a spherical mode expansion. In this region, the angles of incidence are moderately wide, and they are considered in the analysis of the reflectarray to better calculate the actual incident field on the sub-reflectarray elements. This technique increases the accuracy for the prediction of co- and cross-polar patterns and antenna gain respect to the case of using ideal feed models. In the second part, as a preliminary validation, the proposed analysis method has been used to design a dual-reflectarray antenna that emulates previous dual-reflector antennas in Ku and W-bands including a reflectarray as subreflector. The results for the dualreflectarray antenna compare very well with those of the parabolic reflector and reflectarray subreflector; radiation patterns, antenna gain and efficiency are practically the same when the main parabolic reflector is substituted by a flat reflectarray. The results show that the gain is only reduced by a few tenths of a dB as a result of the ohmic losses in the reflectarray. The phase adjustment on two surfaces provided by the dual-reflectarray configuration can be used to improve the antenna performance in some applications requiring multiple beams, beam scanning or shaped beams. Third, a very challenging dual-reflectarray antenna demonstrator has been designed, manufactured and tested for a more rigorous validation of the analysis technique presented. The proposed antenna configuration has the feed, the sub-reflectarray and the main-reflectarray in the near field one to each other, so that the conventional far field approximations are not suitable for the analysis of such antenna. This geometry is used as benchmarking for the proposed analysis tool in very stringent conditions. Some aspects of the proposed analysis technique that allow improving the accuracy of the analysis are also discussed. These improvements include a novel method to reduce the inherent cross polarization which is introduced mainly from grounded patch arrays. It has been checked that cross polarization in offset reflectarrays can be significantly reduced by properly adjusting the patch dimensions in the reflectarray in order to produce an overall cancellation of the cross-polarization. The dimensions of the patches are adjusted in order not only to provide the required phase-distribution to shape the beam, but also to exploit the crosses by zero of the cross-polarization components. The last part of the thesis deals with direct applications of the technique described. The technique presented is directly applicable to the design of contoured beam antennas for DBS applications, where the requirements of cross-polarisation are very stringent. The beam shaping is achieved by synthesithing the phase distribution on the main reflectarray while the sub-reflectarray emulates an equivalent hyperbolic subreflector. Dual-reflectarray antennas present also the ability to scan the beam over small angles about boresight. Two possible architectures for a Ku-band antenna are also described based on a dual planar reflectarray configuration that provides electronic beam scanning in a limited angular range. In the first architecture, the beam scanning is achieved by introducing a phase-control in the elements of the sub-reflectarray and the mainreflectarray is passive. A second alternative is also studied, in which the beam scanning is produced using 1-bit control on the main reflectarray, while a passive subreflectarray is designed to provide a large focal distance within a compact configuration. The system aims to develop a solution for bi-directional satellite links for emergency communications. In both proposed architectures, the objective is to provide a compact optics and simplicity to be folded and deployed.

Structural behaviour and design criteria of under-deck cable-stayed bridges subjected to seismic action

Under-deck cable-stayed bridges are very effective structural systems for which the strong contribution of the stay cables under live loading allows for the design of very slender decks for persistent and transient loading scenarios. Their behaviour when subjected to seismic excitation is investigated herein and a set of design criteria are presented that relate to the type and arrangement of bearings, the number and configuration of struts, and the transverse distribution of stay cables. The nonlinear behaviour of these bridges when subject to both near-field and far-field accelerograms has been thoroughly investigated through the use of incremental dynamic analyses. An intensity measure that reflects the pertinent contributions to response when several vibration modes are activated was proposed and is shown to be effective for the analysis of this structural type. The under-deck cable-stay system contributes in a very positive manner to reducing the response when the bridges are subject to very strong seismic excitation. For such scenarios, the reduction in the stiffness of the deck because of crack formation, when prestressed concrete decks are used, mobilises the cable system and enhances the overall performance of the system. Sets of natural accelerograms that are compliant with the prescriptions of Eurocode 8 were also applied to propose a set of design criteria for this bridge type in areas prone to earthquakes. Particular attention is given to outlining the optimal strategies for the deployment of bearings

Analysis and design of multiagent systems using MAS-CommonKADS

This article proposes an agent-oriented methodology called MAS-CommonKADS and develops a case study. This methodology extends the knowledge engineering methodology CommonKADSwith techniquesfrom objectoriented and protocol engineering methodologies. The methodology consists of the development of seven models: Agent Model, that describes the characteristics of each agent; Task Model, that describes the tasks that the agents carry out; Expertise Model, that describes the knowledge needed by the agents to achieve their goals; Organisation Model, that describes the structural relationships between agents (software agents and/or human agents); Coordination Model, that describes the dynamic relationships between software agents; Communication Model, that describes the dynamic relationships between human agents and their respective personal assistant software agents; and Design Model, that refines the previous models and determines the most suitable agent architecture for each agent, and the requirements of the agent network.

Rapid prototyping for biomedical engineering: current capabilities and Challenges

A new set of manufacturing technologies has emerged in the past decades to address market requirements in a customized way and to provide support for research tasks that require prototypes. These new techniques and technologies are usually referred to as rapid prototyping and manufacturing technologies, and they allow prototypes to be produced in a wide range of materials with remarkable precision in a couple of hours. Although they have been rapidly incorporated into product development methodologies, they are still under development, and their applications in bioengineering are continuously evolving. Rapid prototyping and manufacturing technologies can be of assistance in every stage of the development process of novel biodevices, to address various problems that can arise in the devices' interactions with biological systems and the fact that the design decisions must be tested carefully. This review focuses on the main fields of application for rapid prototyping in biomedical engineering and health sciences, as well as on the most remarkable challenges and research trends.

Unidad didáctica sobre el uso del programa Virtual.Lab para simulaciones acústicas. Parte I

El presente Proyecto de Fin de Carrera supone el propósito conjunto de los alumnos Álvaro Morillas y Fernando Sáez, y del profesor Vladimir Ulin, de desarrollar una unidad didáctica sobre el programa de simulación para ingeniería Virtual.Lab. La versión sobre la que se ha trabajado para realizar este texto es la 11, publicada en agosto de 2012. Virtual.Lab, del fabricante belga LMS International, es una plataforma software de ingeniería asistida por ordenador, que agrupa en una misma aplicación varias herramientas complementarias en el diseño de un producto, desde su definición geométrica a los análisis de durabilidad, ruido u optimización. No obstante, de entre todas las posibles simulaciones que nos permite el programa, en este proyecto sólo se tratan las que están relacionadas con la acústica. Cabe resaltar que gran parte de los conceptos manejados en Virtual.Lab son compatibles con el programa CATIA V5, ya que ambos programas vienen instalados y funcionan conjuntamente. Por eso, el lector de este proyecto podrá transportar sus conocimientos al que es uno de los programas estándar en las industrias aeronáutica, naval y automovilística, entre otras. Antes de este proyecto, otros alumnos de la escuela también realizaron proyectos de fin de carrera en el campo de la simulación computarizada en acústica. Una característica común a estos trabajos es que era necesario hacer uso de distintos programas para cada una de las etapas de simulación (como por ejemplo, ANSYS para el modelado y estudio de la vibración y SYSNOISE para las simulaciones acústicas, además de otros programas auxiliares para las traducciones de formato). Con Virtual.Lab desaparece esta necesidad y el tiempo empleado se reduce. Debido a que las soluciones por ordenador están ganando cada vez más importancia en la industria actual, los responsables de este proyecto consideran la necesidad de formación de profesionales en esta rama. Para responder a la demanda empresarial de trabajadores cualificados, se espera que en los próximos años los planes de estudio contengan más cursos en esta materia. Por tanto la intención de los autores es que este material sea de utilidad para el aprendizaje y docencia de estas asignaturas en cursos sucesivos. Por todo esto, se justifica la relevancia de este PFC como manual para introducir a los alumnos interesados en iniciarse en un sistema actual, de uso extendido en otras universidades tecnológicas europeas, y con buenas perspectivas de futuro. En este proyecto se incluyen varios ejemplos ejecutables desde el programa, así como vídeos explicativos que ayudan a mostrar gráficamente los procesos de simulación. Estos archivos se pueden encontrar en el CD adjunto. Abstract This final thesis is a joint project made by the students Álvaro Morillas and Fernando Sáez, and the professor Vladimir Ulin. The nature of the joint regards the writing of a didactic unit on Virtual.Lab, the simulation software. The software version used in this text is the number 11, released in August 2012. Virtual.Lab, from the Belgian developer LMS International, is a computer-aided engineering software which is used for several related tasks in this field: product design, durability simulation, optimization, etc. However, this project is focused on the acoustical capabilities. It is worthy to highlight that most procedures explained in this text can be used in the software CATIA V5 as well. Both tools come installed together and may be used at the same time. Therefore, the reader of this project will be able to use the acquired knowledge in one of the most relevant softwares for the aerospace, marine and automotive engineering. Previously to the development of this project, this School has conducted projects on this field. These projects regarded the use of ANSYS for modeling and meshing stages as well as the use of SYSNOISE for the final acoustic analysis. Since both systems use different file formats, a third-party translation software was required. This thesis fulfill this pending necessity with Virtual.Lab; the translation software procedure is not necessary anymore and simulations can be done in a more flexible, fast way. Since companies have an increasing usage of numerical methods in the development of their products and services, the authors think that it is important to develop the appropriate method to instruct new professionals in the field. Thus, the aim of this project is to help teachers and students in their process of learning the use of this leading software in acoustical simulations. For all the reasons mentioned above, we consider that this project is relevant for the School and the educational community. Aiming to achieve this objective the author offers example files and video demonstrations with guidance in the CD that accompanies this material. This facilitates the comprehension of the practical tasks and guides the prospect users of the software.

System Engineering Approach to Initial Design of LEO Remote Sensing Missions

The satellite remote sensing missions are essential for long-term research around the condition of the earth resources and environment. On the other hand, in recent years the application of microsatellites is of interest in many space programs for their less cost and response time. In microsatellite remote sensing missions there are tight interrelations between different requirements such as orbital altitude, revisit time, mission life and spatial resolution. Also, all of these requirements can affect the whole system level design characteristics. In this work, the remote sensing microsatellite sizing process is divided into three major design disciplines; a) orbit design, b) payload sizing and c) bus sizing. Finally, some specific design cases are investigated inside the design space for evaluating the effect of different design variables on the satellite total mass. Considering the results of the work, it is concluded that applying a systematic approach at the initial design phase of such projects provides a good insight to the not clearly seen interactions inside their highly extended design space

Analysis and Design Considerations of an Electric Vehicle Powertrain regarding Energy Efficiency and Magnetic Field Exposure

En esta tesis se analiza el sistema de tracción de un vehículo eléctrico de batería desde el punto de vista de la eficiencia energética y de la exposición a campos magnéticos por parte de los pasajeros (radiación electromagnética). Este estudio incluye tanto el sistema de almacenamiento de energía como la máquina eléctrica, junto con la electrónica de potencia y los sistemas de control asociados a ambos. Los análisis y los resultados presentados en este texto están basados en modelos matemáticos, simulaciones por ordenador y ensayos experimentales a escala de laboratorio. La investigación llevada a cabo durante esta tesis tuvo siempre un marcado enfoque industrial, a pesar de estar desarrollada en un entorno de considerable carácter universitario. Las líneas de investigación acometidas tuvieron como destinatario final al diseñador y al fabricante del vehículo, a pesar de lo cual algunos de los resultados obtenidos son preliminares y/o excesivamente académicos para resultar de interés industrial. En el ámbito de la eficiencia energética, esta tesis estudia sistemas híbridos de almacenamiento de energía basados en una combinación de baterías de litio y supercondensadores. Este tipo de sistemas son analizados desde el punto de vista de la eficiencia mediante modelos matemáticos y simulaciones, cuantificando el impacto de ésta en otros parámetros tales como el envejecimiento de las baterías. Respecto a la máquina eléctrica, el estudio se ha centrado en máquinas síncronas de imanes permanentes. El análisis de la eficiencia considera tanto el diseño de la máquina como la estrategia de control, dejando parcialmente de lado el inversor y la técnica de modulación (que son incluidos en el estudio como fuentes adicionales de pérdidas, pero no como potenciales fuentes de optimización de la eficiencia). En este sentido, tanto la topología del inversor (trifásico, basado en IGBTs) como la técnica de modulación (control de corriente en banda de histéresis) se establecen desde el principio. El segundo aspecto estudiado en esta tesis es la exposición a campos magnéticos por parte de los pasajeros. Este tema se enfoca desde un punto de vista predictivo, y no desde un punto de vista de diagnóstico, puesto que se ha desarrollado una metodología para estimar el campo magnético generado por los dispositivos de potencia de un vehículo eléctrico. Esta metodología ha sido validada mediante ensayos de laboratorio. Otros aspectos importantes de esta contribución, además de la metodología en sí misma, son las consecuencias que se derivan de ella (por ejemplo, recomendaciones de diseño) y la comprensión del problema proporcionada por esta. Las principales contribuciones de esta tesis se listan a continuación: una recopilación de modelos de pérdidas correspondientes a la mayoría de dispositivos de potencia presentes en un vehículo eléctrico de batería, una metodología para analizar el funcionamiento de un sistema híbrido de almacenamiento de energía para aplicaciones de tracción, una explicación de cómo ponderar energéticamente los puntos de operación par-velocidad de un vehículo eléctrico (de utilidad para evaluar el rendimiento de una máquina eléctrica, por ejemplo), una propuesta de incluir un convertidor DC-DC en el sistema de tracción para minimizar las pérdidas globales del accionamiento (a pesar de las nuevas pérdidas introducidas por el propio DC-DC), una breve comparación entre dos tipos distintos de algoritmos de minimización de pérdidas para máquinas síncronas de imanes permanentes, una metodología predictiva para estimar la exposición a campos magnéticos por parte de los pasajeros de un vehículo eléctrico (debida a los equipos de potencia), y finalmente algunas conclusiones y recomendaciones de diseño respecto a dicha exposición a campos magnéticos. ABSTRACT This dissertation analyzes the powertrain of a battery electric vehicle, focusing on energy efficiency and passenger exposure to electromagnetic fields (electromagnetic radiation). This study comprises the energy storage system as well as the electric machine, along with their associated power electronics and control systems. The analysis and conclusions presented in this dissertation are based on mathematical models, computer simulations and laboratory scale tests. The research performed during this thesis was intended to be of industrial nature, despite being developed in a university. In this sense, the work described in this document was carried out thinking of both the designer and the manufacturer of the vehicle. However, some of the results obtained lack industrial readiness, and therefore they remain utterly academic. Regarding energy efficiency, hybrid energy storage systems consisting in lithium batteries, supercapacitors and up to two DC-DC power converters are considered. These kind of systems are analyzed by means of mathematical models and simulations from the energy efficiency point of view, quantifying its impact on other relevant aspects such as battery aging. Concerning the electric machine, permanent magnet synchronous machines are studied in this work. The energy efficiency analysis comprises the machine design and the control strategy, while the inverter and its modulation technique are taken into account but only as sources of further power losses, and not as potential sources for further efficiency optimization. In this sense, both the inverter topology (3-phase IGBT-based inverter) and the switching technique (hysteresis current control) are fixed from the beginning. The second aspect studied in this work is passenger exposure to magnetic fields. This topic is approached from the prediction point of view, rather than from the diagnosis point of view. In other words, a methodology to estimate the magnetic field generated by the power devices of an electric vehicle is proposed and analyzed in this dissertation. This methodology has been validated by laboratory tests. The most important aspects of this contribution, apart from the methodology itself, are the consequences (for instance, design guidelines) and the understanding of the magnetic radiation issue provided by it. The main contributions of this dissertation are listed next: a compilation of loss models for most of the power devices found in a battery electric vehicle powertrain, a simulation-based methodology to analyze hybrid energy storage performance in traction applications, an explanation of how to assign energy-based weights to different operating points in traction drives (useful when assessing electrical machine performance, for instance), a proposal to include one DC-DC converter in electric powertrains to minimize overall power losses in the system (despite the new losses added by the DC-DC), a brief comparison between two kinds of loss-minimization algorithms for permanent magnet synchronous machines in terms of adaptability and energy efficiency, a predictive methodology to estimate passenger magnetic field exposure due to power devices in an electric vehicle, and finally some useful conclusions and design guidelines concerning magnetic field exposure.

Shore protection, planning and design.

Includes bibliographical references (section C).