No description available.

Em radioterapia externa, uma nova técnica chamada terapia de radiação de intensidade modulada - IMRT - permite delinear a dose de radiação em imagens de 2 ou 3 dimensões, delimitando de forma bastante precisa e não necessariamente uniforme a região a ser irradiada. Assim, ao mesmo tempo que o tumor é irradiado, é possível evitar a irradiação aos tecidos vizinhos íntegros (sãos), limitando os efeitos secundários do tratamento. Para que a radioterapia externa tenha sucesso usando a técnica IMRT, é fundamental delinear previamente de forma precisa o tumor e os órgãos sãos que devem ser protegidos da radiação, garantindo assim a dose exata de radiação nos volumes alvos. O objetivo desta tese é fornecer ferramentas que sejam adequadas ao delineamento automático de estruturas de interesse e à radioterapia adaptativa para tumores da região da cabeça e do pescoço. Atualmente, a segmentação de estruturas de interesse, tais como os órgãos em risco e as regiões de propagação tumoral, é feita manualmente. Esta é uma tarefa que demanda bastante tempo de um especialista, além de ser tediosa. Além do mais, o planejamento em radioterapia é feito baseado na imagem adquirida na semana do pré-tratamento, onde é calculada a dose. Normalmente o tratamento ocorre em várias semanas, porém a dose estimada no início do tratamento é a mesma para todas as outras semanas do tratamento. Calcular a dose e mantê-la nas demais semanas é uma simplificação que não corresponde à realidade, já que ocorrem mudanças anatômicas no paciente ao longo do tratamento. Estas mudanças ocorrem devido ao encolhimento do tumor e ao possível emagrecimento do paciente, provocando alterações anatômicas locais e globais. As contribuições desta tese visam solucionar e avançar nestes problemas e são apresentadas em dois eixos. No primeiro eixo, é proposta uma metodologia para escolher uma anatomia que seja representativa da população, anatomia esta chamada de atlas. O registro do atlas na imagem do paciente permite que estruturas de interesse sejam segmentadas automaticamente, acelerando o processo de delineamento e tornando-o mais robusto. A segunda contribuição desta tese é voltada à radioterapia adaptativa. Para que a dose estimada na primeira semana seja adaptada às modificações anatômicas, é necessária a utilização de métodos de registro não-rígidos. Portanto, nesta etapa é feita uma avaliação e adaptação dos métodos de registros de forma que a região do tumor esteja bem alinhada. / Intensity Modulated Radiotherapy (IMRT) is a new technique enabling the delineation of the 3D radiation dose. It allows to delineate a radiation zone of almost any shape and to modulate the beam intensity inside the target. If IMRT enables to constrain the radiation plan in the beam delivery as well as in the protection of important functional areas (e.g. spinal cord), it also raises the issues of adequacy and accuracy of the selection and delineation of the target volumes. The purpose of this thesis is to provide tools to automatic delineation of the regions of interest and also to adaptive radiotherapy treatment for tumors located in the head and neck region. The delineation in the patient computed tomography image of the tumor volume and organs to be protected is currently performed by an expert who delineates slice by slice the contours of interest. This task is highly time-consuming and requires experts’ knowledge. Moreover, the planning process in radiotherapy typically involves the acquisition of a unique set of computed tomography images in treatment position on which target volumes (TVs) and normal structures are delineated, and which are used for dose calculation. Restricting the delineation of these regions of interest based solely on pre-treatment images is an oversimplification as it is only a snapshot of the patient´s anatomy at a given time. Shrinkage of the tumor and modification of the patient anatomy at large (e.g. due to weight loss) may indeed occur within the several weeks’ duration of a typical treatment. The main contributions of this thesis aim to advance in the solution to these issues and are presented in two axes. In the first one, it is proposed a methodology to choose an image with the most representative anatomy of a population; such image is called Atlas. The registration of the atlas into a new image of the patient allows to automatically segment the structures of interest, speeding up the delineation process and making it more robust. The second contribution of this thesis is focused on the adaptive radiotherapy. In order to adjust the estimated dose to the anatomical modifications, it is fundamental to have non-rigid registration algorithms. So, the evaluation and adaptation of non-rigid registration methods are required, addressing especially the alignment of the tumor’s region among different moments of the treatment.

abstract: Gallium Nitride (GaN) based Current Aperture Vertical Electron Transistors (CAVETs) present many appealing qualities for applications in high power, high frequency devices. The wide bandgap, high carrier velocity of GaN make it ideal for withstanding high electric fields and supporting large currents. The vertical topology of the CAVET allows for more efficient die area utilization, breakdown scaling with the height of the device, and burying high electric fields in the bulk where they will not charge interface states that can lead to current collapse at higher frequency. Though GaN CAVETs are promising new devices, they are expensive to develop due to new or exotic materials and processing steps. As a result, the accurate simulation of GaN CAVETs has become critical to the development of new devices. Using Silvaco Atlas 5.24.1.R, best practices were developed for GaN CAVET simulation by recreating the structure and results of the pGaN insulated gate CAVET presented in chapter 3 of [8]. From the results it was concluded that the best simulation setup for transfer characteristics, output characteristics, and breakdown included the following. For methods, the use of Gummel, Block, Newton, and Trap. For models, SRH, Fermi, Auger, and impact selb. For mobility, the use of GANSAT and manually specified saturation velocity and mobility (based on doping concentration). Additionally, parametric sweeps showed that, of those tested, critical CAVET parameters included channel mobility (and thus doping), channel thickness, Current Blocking Layer (CBL) doping, gate overlap, and aperture width in rectangular devices or diameter in cylindrical devices. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2019

This thesis reports on our initial work constructing a human lung query atlas which provides clinically relevant population statistics for normal and abnormal individuals. The atlas incorporates front-end interfaces with back-end database. The interfaces were developed using Microsoft Access 2007 and the database was implemented using MySQL. ODBC was used to import database into Access and provide connection for database and interfaces. VBA is used to write SQL queries and realized the interaction with interfaces. SQL queries is written to extract the data which researchers may interest in. The atlas provides measurements of the human airway tree and lung volumes from a population of individuals and also provides a population statistics based on age, race, ethnicity, gender and other information. It also provides functionality for comparing airway measurements between populations, individuals to a population, and individuals to individuals. Statistical significance, such as p-value, is provided to analyze two individuals or populations.

The high resolution silicon Pixel detector is critical in event vertex reconstruction and in particle track reconstruction in the ATLAS detector. During the pixel data taking operation, some modules (Silicon Pixel sensor +Front End Chip+ Module Control Chip (MCC)) go to an auto-disable state, where the Modules don't send the data for storage. Modules become operational again after reconfiguration. The source of the problem is not fully understood. One possible source of the problem is traced to the occurrence of single event upset (SEU) in the MCC. Such a module goes to either a Timeout or Busy state. This report is the study of different types and rates of errors occurring in the Pixel data taking operation. Also, the study includes the error rate dependency on Pixel detector geometry.

Leptoquarks are hypothetical particles that attempt to explain the coincidental similarities between leptons and quarks included in SM. Their exact properties vary between different theoretical models, and there are no strong theoretical constraints on their possible mass values. They can possibly be produced from particle collisions, and there have already been searching efforts at previous collider experiments. Their presence have yet been observed, and this fact has been translated into lower bound exclusions on their possible mass values. The Large Hadron Collider (LHC) being the most recently constructed particle collider with the highest collision energies ever achieved experimentally, provides a new platform to continue the search for Leptoquarks at even higher mass ranges. This thesis describes a search for pair-produced second-generation Leptoquarks using 20.3 fb−1 of data recorded by the ATLAS detector of LHC at √s = 8 TeV. Events with two oppositely charged muons and two or more jets in the final state were used. Candidate leptoquark events were selected with the help of four observables: the di-muon invariant mass (Mμμ ), the sum of the pT of the two muons (LT ), the sum of the pT of the two leading jets (HT ) and the average Leptoquark mass (MLQ ). Monte Carlo simulations of SM background processes have shown to be in good agreement with data, both in the region constructed using selection requirements for candiate leptoquark events and in the designated control regions. Since no significant excess of events was observed in data, a exclusion limit was set as a function of the Leptoquark mass. / Leptoquarks sind hypothetische Teilchen, mit deren Hilfe versucht wird die zufälligen Ähnlichkeiten zwischen den im Standardmodell enthaltenen Leptonen und Quarks zu erkl� ären. Ihre exakten Eigenschaften variieren zwischen verschiedenen theoretischen Modellen und es gibt keine starken theoretischen Beschr� änkungen auf ihre möglichen Massen. Sie können wohl bei Teilchenkollisionen erzeugt werden und es gab bereits an früheren Beschleuniger-Experimenten Bem� ühungen bei der Suche nach ihnen. Ihre Existenz konnte bisher nicht beobachtet werden, was in untere Ausschlussgrenzen f� ür m� ögliche Massen übertragen wurde. Der zuletzt gebaute Teilchenbeschleuniger, der Large Hadron Collider (LHC) erreicht die bisher höchsten Kollisionsenergien und bietet damit eine neue Grundlage, um die Suche nach Leptoquarks bei noch höheren Massenregionen fortzusetzen. (...)

Aucun

L'expérience ATLAS, dont les prises de données d'ébuteront en 2007 auprès du collisionneur proton-proton LHC, possède un calorimètre électromagnètique à échantillonnage plomb-argon très performant. La présente thèse se propose d'étudier la réponse et l'uniformité du calorimètre à partir des muons contaminant le faisceau de test des modules. Cette étude a permis de confirmer l'existence d un problème de conception des électrodes du calorimètre. Le bruit de phase des horloges de synchronisation et d'échantillonnage est aussi étudié, ainsi que son impact sur la reconstruction des signaux d'électronique du calorimètre. Enfin, nous tentons d'exploiter les données du temps de vol des particules fournies par le calorimètre via la reconstruction des signaux par filtrage optimal. En particulier, nous montrons que la position du point d'interaction peut être mesurée avec une précision du même ordre de grandeur que la taille des paquets de protons.

Cette thèse est consacrée à l'étude des désintégrations radiatives des mésons B dans le détecteur ATLAS du LHC. Les désintégrations radiatives sont une famille des désintégrations rares, transitions impliquant des changements de saveurs par courants neutres (processus b-->s\gamma par exemple), interdits à l'ordre le plus bas dans le Modèle Standard. Ces processus interviennent par le biais de diagrammes du second ordre (diagrammes pingouin et boîte), et sont donc particulièrement sensibles aux contributions de nouvelles particules telles que les bosons de Higgs chargés ou les particules supersymétriques. Le but de l'étude est de montrer qu'il sera possible de sélectionner en ligne les désintégrations radiatives dans ATLAS. Pour ce faire, le traitement des photons de basse énergie par le calorimètre électromagnétique d'ATLAS (ECal) est étudié précisément. Le travail présenté ici montre que le ECal sera en mesure de traiter ce type de particules. Cette propriété est largement utilisée dans la partie suivante, au cours de laquelle est développée une stratégie de sélection des désintégrations radiatives. La méthode proposée s'appuie en effet sur la recherche d'une zone de basse énergie dans le ECal dès le niveau 1 du processus de sélection, et sur l'identification précise du photon dès le niveau 2. Une grande partie de la stratégie présentée concerne également le détecteur interne, en particulier au niveau 2 du déclenchement. Les résultats obtenus montrent qu'il sera possible de selectionner à court terme une quantité importante de signal, et ce en respectant les contraintes imposées par le trigger d'ATLAS.

<p>This master thesis is Atlas Copco Craelius’ first step in incorporating numericalmethods in load case analysis during the development process. Atlas Copco needs toconstantly evolve and refine their methods in the design process to remain as thenumber one manufacturer of mining and construction equipment. Poor knowledge ofloads results either in structural failures or in oversized structures, both very costlyfor Atlas Copco.The main goal of this thesis is to examine the potential in MBS software by using it toidentify extreme load cases in one of Atlas Copco Craelius’ surface drill rigs, Mustang5. The MBS-software ADAMS View is used to build a model of the Mustang 5 drill rigand evaluate simulation results. The rig model is subject to motions which representreal case scenarios. The feed positioning possibilities are examined thoroughly since it was expected that the positioning has impact on the load levels. 25 different feedpositioning are simulated.The main conclusion is that the load levels are highly dependent on the feedpositioning. For example, the load levels in the boom raising cylinder can increaseseven times, if the rig is operated with the most unfavorable positioning compared tothe recommended. It could also be concluded that not only one positioning isextreme in terms of loads; it depends on which part of the boom system is beingobserved. Thus, several positioning cases have to be taken into consideration in orderto optimize the design of parts in the boom system.</p>