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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Napájecí zdroj pro vesmírné aplikace / Power supply for space application

Hrubý, Lukáš January 2018 (has links)
The following work deals with a design of switched mode power supply. In this essay, there is detailed description of non-isolated and isolated topologies of SMPS, used in industry. Next, there are calculations for design and analysis which are needed for space design. There will also be selected devices, which could be used in final device. Based on experience and ECSS requirements, there will be chosen parameters of SMPS, which could be then used as a module for future space design. Chosen topology of SMPS will be created as engineering model assembled with commercial components. One part of this work is dedicated to design and realization of planar transformer and coupled inductor.
2

Estudo de interferência eletromagnética de radiofrequência entre sistemas de comunicação na faixa de micro-ondas a bordo de um submarino. / Co-site interference study between communication systems at microwave frequency band onboard a submarine.

Klingelfus, Vitor Teixeira 12 April 2019 (has links)
Um navio de guerra é considerado uma plataforma complexa no que tange o projeto de sistemas de comunicação RF, uma vez que diversos desempenhos devem ser considerados para sua adequada integração à mesma. Dentre eles está o controle da interferência de radiofrequência conhecida como co-site interference, causada primariamente pela alta potência radiada de alguns sistemas emissores em relativa proximidade física entre antenas à sistemas receptores de considerável sensibilidade. É o caso do sistema de comunicação civil satelital Inmarsat FB e do receptor GPS civil marítimo, os quais são encontrados em diversos navios mercantes e de guerra e têm frequências de operação próximas. Logo, esta dissertação foca na modelagem e estudo da interferência de radiofrequência entre um emissor Inmarsat FB civil em 1627 MHz (perturbador) e um sistema receptor GPS marítimo (vítima) em 1575 MHz, com suas respectivas antenas em proximidade física a bordo de um submarino; neste estudo, o classe Los Angeles original SSN-688. Adicionalmente, este estudo projeta mitigações para controlar e prevenir tal interferência. A metodologia proposta consiste na determinação do \"caminho da interferência\" por meio de simulação eletromagnética 3D da isolação eletromagnética entre as antenas perturbadora e perturbada em diferentes hipóteses de alocação nos mastros do SSN-688; caracterização dos efeitos da RFI causados pelo sinal interferente na recepção do sinal desejado, utilizando modelo de circuito cabeça de RF de um receptor típico GPS marítimo em avançado simulador de circuitos incluindo suas respectivas não linearidades; e na proposta, projeto, e fabricação de mitigações adequadas: neste estudo pré-filtros de micro-ondas em tecnologia planar de microfita. O desempenho dos pré-filtros fabricados é comparado com a simulação e com os requisitos de projeto, de maneira a adequadamente mitigar e controlar a interferência. / A war ship is considered a complex environment when it comes to the design of RF communication systems, since several performances must be considered for their integration into the platform. Among them is the control of co-site interference, mainly caused by high power transmitters co-located with sensitive receivers on an antenna to antenna limited space environment, such as on a submarine. It is the case of civilian Inmarsat FB satellite communication and maritime GPS systems, which are both typically encountered on several war and merchant ships and share close frequency bands. Therefore, this dissertation focuses on modelling and studying the RF interference between a civilian Inmarsat FB emitter on 1627 MHz (culprit) and a GPS maritime receiving system on 1575 MHz (victim) on close antennas proximity onboard a submarine: in this study the US Navy retired Los Angeles SSN-688 original class. Additionally, it proposes design of mitigations to attenuate and prevent such interference. The proposed methodology consists on determining the \"interference path\" by 3D EM simulation of the electromagnetic decoupling between culprit and victim\'s antennas on different antenna placement hypothesis onboard the SSN-688\'s masts; estimating the RFI effects on a typical GPS front end receiver circuit model on advanced circuit simulator including its non-linearities; and on proposing, designing and fabricating adequate mitigations: in this study microwave pre-filters based on planar microstrip technology. The performance of the pre-filters fabricated is compared with the simulation and with the requirements in order to attenuate and mitigate as much as possible the detected RFI.
3

Caractérisation de matériaux plasmas pour la conception de fonctions hyperfréquences / Characterization of plasma media for the design of hyperfrequency functions

Chruszez, Olivier 04 February 2015 (has links)
Afin de mettre à profit les propriétés des plasmas pour développer des fonctions hyperfréquences originales, le milieu plasma doit d’abord être caractérisé dans cette gamme de fréquence car son expansion et sa densité, supposée homogène, sont des paramètres mal maîtrisés. Une méthode de mesure de la constante diélectrique du plasma a donc été développée pour déterminer une permittivité relative complexe moyenne dans les conditions d’utilisation et d’excitation. A partir d’un modèle basé sur une méthode modale, et de la mesure de fréquence de résonance d’un résonateur, on caractérise un milieu plasma (permittivité, fréquence de coupure plasma) généré au sein d’une ligne microruban multicouches. Cette thèse, à l’intersection entre deux disciplines, plasmas et micro-ondes, valide l’utilisation de plasma localisé au sein d’une technologie planaire multicouches pour dimensionner des lignes d’impédance et/ou longueur de ligne variables. Elle met également en avant les difficultés rencontrées en termes de réalisation, pour générer des plasmas reproductibles et stables. / In order to take profits of the plasma properties to develop new hyperfrequency funtioncs, the plasma media must be first characterize in this frequency range because his expansion and density, supposed homogeneous, are parameters not well known. A method of measurement of the plasma’s dielectric constant have been developped to determine an average relative complexe permittivity in the condition of use and excitation. From this method based on a modal method, and from the measurement of the resonant frequency, we can characterize the plasma media (permittivity, cut-off frequency of the plasma) generated within a multilayer microstrip line. This thesis, which verge on the junction between two major fields : microwaves and plasma physics, allowed us to ascertain on the local use of plasma media within multilayer planar technology, in order to design lines with variable impedance and/or variable electrical length. It also highlights on the major difficulties with the generation of stable and reproductible plasma.
4

Advanced planar pixel technology developments for ATLAS upgrade phase 2 / Avancées technologiques dans le domaine des pixels planaires pour l'expérience ATLAS Phase 2

Hohov, Dmytro 01 October 2019 (has links)
Le complexe d'accélérateurs du grand collisionneur de hadrons (le Large Hadron Collider - LHC) sera mis à jour lors du long arrêt de la période LS3 en 2023-2025 pour passer à la phase de haute luminosité (HL-LHC). La luminosité instantanée sera multipliée par 5 pour atteindre 7.5×10³⁴ cm⁻²s⁻¹, ce qui correspond à environ 200 collisions inélastiques par croisement de paquets comparé aux 50 par croisement au LHC. Pendant le fonctionnement du HL-LHC, afin d'atteindre une haute précision dans les études des processus physiques du modèle standard et les recherches de nouvelle physique, le collisionneur à protons devra fournir une luminosité intégrée de l’ordre 400 fb⁻¹ par an pendant une dizaine d’années soit 4000 fb⁻¹ escomptées. Ceci représente un ordre de grandeur supérieur à l'ensemble de la période du LHC. Le détecteur interne (Inner Detector) ATLAS actuel ne sera pas en mesure de faire face efficacement à l'augmentation du taux d'événements et de la dose de rayonnement. Afin d’obtenir des performances au minimum égales ou supérieures à celles de la phase LHC, et tenant compte d’un environnement plus hostile en termes de radiations et d’empilements d’évènements, il a été décidé d’opérer le remplacement complet du trajectomètre interne ou Inner Tracker (ITk); à cette fin, une technologie tout silicium a été choisie. Cette thèse est axée sur l'étude de nouveaux capteurs pixels planaires fins à bords très minces, basés sur le concept d’utilisation de matrices de diodes à implants dopés n sur un substrat dopé p. Ce choix est motivé par les critères de meilleure performance intrinsèque, de radio-tolérance élevée ainsi qu’un coût de production optimisé pour de grandes surfaces. Dans ce travail, des capteurs de différentes épaisseurs allant de 50 μm à 150 μm dotés de bords actifs et minces ont fait l’objet d’études approfondies notamment lors de leur fonctionnement à haut flux de particules chargées. De nombreuses analyses minutieuses ont été menées pour déterminer leur résolution en position à l’aide d’un télescope de faisceau de haute énergie. Les régions d’impacts sur la zone active des pixels ainsi que sur la région des contours ont été scrutées avant et après leur irradiation. En effet, de nombreux résultats obtenus en faisceau de protons et électrons seront montrés, notamment une étude comparative des différents concepts de matrices de capteurs de pixels planaires lus avec la puce de lecture « FE-I4 » en technologie CMOS 130 nm. Préparant la phase future du LHC, nous montrerons les premiers résultats obtenus avec la nouvelle génération de pixels granulaires. Ces matrices ont été couplées à la nouvelle puce de lecture frontale récemment développée au CERN, utilisant la technologie CMOS 65 nm. Ces capteurs dotés d’ une plus fine granularité de 50×50 μm² , ont un pas optimisé lequel est nécessaire pour maintenir un taux d'occupation aussi bas que possible dans un contexte de multiplicités de particules chargées très élevées. Dans ce travail, une contribution personnelle à l’électronique de lecture sera détaillée, en particulier les études ont été menées sur la puce nommée «Ring-Oscillator» ou moniteur de radiations, développée au laboratoire. On décrira son comportement dynamique en fonction de la température, de la tension nominale et en conditions hautement radiatives (500 MRad). La mise au point d’un nouvel outil de caractérisation de détecteurs pixels a fait l’objet d’un développement important. Grâce à un ensemble basé sur une excitation laser de 1060 nm, il sera possible de disposer d’un système précis et autonome capable de mesurer rapidement les caractéristiques fonctionnelles des matrices de pixels avec une excellente résolution spatiale. Les caractéristiques de cet outil feront l’objet d’une présentation exhaustive. / The Large Hadron Collider (LHC) will go through the accelerator complex upgrade during the LS3 long shutdown in 2023-2025 to move to the High Luminosity phase (HL-LHC). As a result, an instantaneous luminosity will increase sevenfold to 7.5×10³⁴ cm⁻²s⁻¹, corresponding to approximately 200 inelastic collisions per bunch-crossing, whereas the LHC runs resulted in up to 50 collisions per bunch-crossing. During the operation of the HL-LHC, in order to achieve high-precision in studies of Standard Model processes and searches for new physics, about 4000 fb⁻¹ of integrated luminosity be collected, which is of an order of magnitude larger than over the entire LHC period. The present ATLAS Inner Detector (ID) will not be able to efficiently cope with the increased event rate and radiation dose. Due to this fact the complete replacement of the ID is foreseen with fully silicon Inner Tracker (ITk) to provide high tracking performance in harsher environment delivered by the HL-LHC. This thesis is focused on the study of new n+-in-p planar silicon sensors, as a promising option to instrument the ITk pixel layers, considering their radiation hardness and cost-effectiveness. Sensors of different thicknesses ranging from 50 µm to 150 µm of active and slim edge designs have been tested at a high energy particle beam to investigate hit efficiency performance analyzed on the pixel active area and on the edge area before and after irradiation. The test beam results and their comparison for the different designs of the pixel sensors compatible with FE-I4 readout chip are discussed. Also, the first results on test beam characterization of the pixel modules employing a newly developed prototype of readout chip for the ITk, RD53A chip, implemented in 65 nm CMOS technology, were obtained. The sensors with the decreased to 25×100 µm² and 50×50 µm² pixel pitch to maintain the lower level of occupancy at high particle multiplicity were measured. Additionally, the tests of ring oscillators, contained in RD53A chip, which may be used as a monitor of the received radiation dose, were carried out depending on temperature, supplied voltage and irradiation level up to 500 MRad. Finally, the test bench setup for silicon pixel detectors characterization using an infra-red laser has been the subject of an original development in this thesis. The setup was developed in the clean room at Laboratoire de l'accélérateur linéaire (LAL) and it is capable of rapidly measuring the functional characteristics, providing a flexible charge injection with well-defined hit position to characterize the silicon pixel matrixes. The software to control the setup was created using LabVIEW programming environment. The results of the measurements with the FE-I4 module implemented with openings allowing the laser beam passage on a sensor backside are presented in this thesis.

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