In this thesis we study methods for solving the neutron transport equation (or linear Boltzmann equation). This is an integro-differential equation that describes the behaviour of neutrons during a nuclear fission reaction. Applications of this equation include modelling behaviour within nuclear reactors and the design of shielding around x-ray facilities in hospitals. Improvements in existing modelling techniques are an important way to address environmental and safety concerns of nuclear reactors, and also the safety of people working with or near radiation. The neutron transport equation typically has seven independent variables, however to facilitate rigorous mathematical analysis we consider the monoenergetic, steady-state equation without fission, and with isotropic interactions and isotropic source. Due to its high dimension, the equation is usually solved iteratively and we begin by considering a fundamental iterative method known as source iteration. We prove that the method converges assuming piecewise smooth material data, a result that is not present in the literature. We also improve upon known bounds on the rate of convergence assuming constant material data. We conclude by numerically verifying this new theory. We move on to consider the use of a specific, well-known diffusion equation to approximate the solution to the neutron transport equation. We provide a thorough presentation of its derivation (along with suitable boundary conditions) using an asymptotic expansion and matching procedure, a method originally presented by Habetler and Matkowsky in 1975. Next we state the method of diffusion synthetic acceleration (DSA) for which the diffusion approximation is instrumental. From there we move on to explore a new method of seeing the link between the diffusion and transport equations through the use of a block operator argument. Finally we consider domain decomposition algorithms for solving the neutron transport equation. Such methods have great potential for parallelisation and for the local application of different solution methods. A motivation for this work was to build an algorithm applying DSA only to regions of the domain where it is required. We give two very different domain decomposed source iteration algorithms, and we prove the convergence of both of these algorithms. This work provides a rigorous mathematical foundation for further development and exploration in this area. We conclude with numerical results to illustrate the new convergence theory, but also solve a physically-motivated problem using hybrid source iteration/ DSA algorithms and see significant reductions in the required computation time.

Les données accumulées sur les mouvements du sol apportent des connaissances très importantes sur les processus de rupture des séismes, les caractéristiques du milieu de propagation, la relation entre le mouvement du sol et les dommages des structures... Cependant, les séismes de faible et moyenne amplitude étant plus fréquents que les grands événements sismiques, les bases de données de mouvements de sol utilisées dans le développement de modèles de prédiction du mouvement du sol ne contiennent pas beaucoup de données de forts séismes. Le point le plus critique concerne les stations proches de la rupture de la faille, pour lesquelles les bases de données restent mal échantillonnées. Les pays à sismicité modérée ou élevée pour lesquels des failles majeures peuvent se briser à proximité de ses grandes villes, sont donc confrontés à un risque sismique majeur, mais le manque d’enregistrements du mouvement ne permet pas une bonne prédiction des mouvements fort du sol. Il est donc nécessaire de simuler le mouvement fort en champ proche. Cette thèse est divisée en 2 parties. La partie 1 se concentre sur une meilleure compréhension de la rupture sismique et de son rapport avec le mouvement du sol proche de la faille. Les mécanismes de génération des valeurs de pics du mouvement du sol sont étudiés pour des ruptures homogènes et hétérogènes. Une analyse quantitative de sensibilité du mouvement du sol aux paramètres cinématiques de la rupture est présentée, pour des sites au voisinage de la rupture ainsi qu’en champ lointain. Un second chapitre est consacré à un effet de source majeur en champ proche: l’effet de directivité. Ce phénomène se produit lorsque la rupture se propage vers un site, avec une vitesse de rupture proche de la vitesse de l'onde de cisaillement Vs; les ondes se propageant vers le sites interfèrent de manière constructive et génèrent une onde de grande amplitude appelée pulse. Les caractéristiques de ce pulse, notamment sa durée, représentent des paramètres d’intérêt pour le génie parasismique. Une équation simple est présentée pour relier la durée du pulse à la configuration géométrique de la rupture et du site d'intérêt et aux paramètres de la source. La partie 2 est consacrée à une meilleure estimation de l’aléa sismique au Liban en simulant le mouvement fort pour des sites proches de la faille principale: la faille de Yammouneh. Le Liban est situé dans un environnement tectonique actif où le risque sismique est considéré comme modéré à élevé. Historiquement, des tremblements de terre destructifs se sont produits dans le passé, le dernier remontant à 1202. Cependant, en raison de la sismicité de grande ampleur actuellement peu fréquente, aucun mouvement fort n'a jamais été enregistré au Liban à ce jour. La faille de Yammouneh est une grande faille en décrochement traversant le Liban du Nord au Sud, situant toutes les villes et infrastructures à moins de 25km de la faille. Une tomographie de la structure de la croûte du Liban, en termes de vitesse des ondes de cisaillement Vs, est réalisée en utilisant le bruit ambiant. À notre connaissance, il s’agit de la première étude de la tomographie Vs 3D au Liban. Par la suite, une approche hybride est utilisée pour simuler le mouvement du sol en champ proche sur une large bande de fréquences (0.1-10Hz). Aux basses fréquences (≤1Hz), des ruptures potentielles de M7 sont simulées (comme définie dans les chapitres précédents), et les fonctions sources obtenues sont convoluées aux fonctions de Green calculées pour le modèle de propagation des ondes issu de la tomographie Vs afin d’estimer le mouvement du sol à proximité de la faille. Le mouvement du sol est complété par un contenu haute fréquence (jusqu’à 10 Hz), en utilisant un modèle stochastique calibré par des enregistrements en champ proche, et en tenant compte de la phase impulsive due à la directivité de la rupture. / Accumulated data of strong ground motions have been providing us very important knowledge about rupture processes of earthquakes, propagation-path, site-amplification effects on ground motion, the relation between ground motion and damage... However, most of the ground motion databases used in the development of ground motion prediction models are primarily comprised of accelerograms produced by small and moderate earthquakes. Hence, as magnitude increases, the sets of ground motions become sparse. Ground motion databases are poorly sampled for short source-to-site distance ranges (‘Near-fault’ ranges). However, the strongest ground shaking generally occurs close to earthquake fault rupture. Countries of moderate to high seismicity for which major faults can break in the vicinity of its major cities are facing a major seismic risk, but the lack of earthquake recordings makes it difficult to predict ground motion. Strong motion simulations may then be used instead. One of the current challenges for seismologists is the development of reliable methods for simulating near-fault ground motion taking into account the lack of knowledge about the characteristics of a potential rupture. This thesis is divided into 2 parts. Part 1 focuses on better understanding the seismic rupture process and its relation with the near-fault ground motion. The mechanisms of peak ground motion generating are investigated for homogeneous as well as for heterogeneous ruptures. A quantitative sensitivity analysis of the ground motion to the source kinematic parameters is presented, for sites located in the vicinity of the fault rupture, as well as far from the rupture. A second chapter is dedicated to a major near-fault source effect: the directivity effect. This phenomenon happens when the rupture propagates towards a site of interest, with a rupture speed close to the shear-wave speed (Vs); the waves propagating towards the site adds up constructively and generates a large amplitude wave called the pulse. The features of this pulse are of interest for the earthquake engineering community. In this chapter, a simple equation is presented that relates the period of the pulse to the geometric configuration of the rupture and the site of interest, and to the source parameters.Part 2 is dedicated to better estimate the seismic hazard in Lebanon by simulating the strong ground motion at sites near the main fault (the Yammouneh fault). Lebanon is located in an active tectonic environment where the seismic hazard is considered moderate to high. Historically, destructive earthquakes occurred in the past, the last one dates back to 1202. However, strong motion has never been recorded in Lebanon till now due to the presently infrequent large-magnitude seismicity, and therefore facing an alarming note of potential new ruptures. The Yammouneh fault is a large strike-slip fault crossing Lebanon, making all its regions located within 25km away from the fault. At first, the crustal structure tomography of Lebanon, in terms of Vs, is performed using the ambient noise, in order to characterise the wave propagation from the rupture to the ground surface. To our knowledge, this is the first study of the 3D Vs tomography in Lebanon. Afterwards, a hybrid approach is presented to simulate broadband near-fault ground motion . At low-frequencies (≤1Hz), potential ruptures of M7 are simulated (as defined in the previous chapters), and the generated slip rate functions are convolved with the Green’s functions computed for the propagation medium defined by the Vs tomography. The ground-motion is complemented by a high-frequency content (up to 10Hz), using a stochastic model calibrated by near-fault recordings and accounting for the presence of the directivity pulse. The computed peak ground acceleration is compared to the design acceleration in Lebanon.

QC 20100618

In this thesis work construction of the angular acceleration signal of a 2-DOF gimbal platform and use of this signal for improving the stabilization performance is aimed. This topic can be divided into two subtopics, first being the construction of angular acceleration and the second being the use of this information in a way to improve system performance. Both problems should be tackled in order to get satisfactory results. The most important output of this work is defined as the demonstration of the improvements obtained both theoretically and on experimental setup. Although the system to be studied is a two axis gimbal platform, the results obtained can be applied to other servo control problems. It is possible to define different performance criteria for a servo control problem and different techniques will be addressed with different control objectives. For this thesis work, the performance criterion is defined as the stabilization performance of the platform. As a result, disturbance rejection characteristics of the controller emerges as the main topic and methods for rejecting these disturbances such as the friction torques and externally applied moments are focused on throughout the studies. As expected, remarkable improvement is achieved as a result of the use of acceleration feedback.

Die vorliegende Ausgabe beschäftigt sich mit dem Thema „Beschleunigung und Entschleunigung – Eine empirische Untersuchung der Zahlungsbereitschaft für Entschleunigung“. Die allgemeine Beschleunigung der Lebensbereiche des Menschen zieht zunehmend negative ökonomische, soziale und ökologische Konsequenzen nach sich. Um diesem Trend entgegen zu wirken, wird die Strategie der Entschleunigung immer mehr zum Gegenstand wissenschaftlicher Betrachtungen. Wird die Notwendigkeit eines entschleunigten Lebenswandels jedoch von der Bevölkerung wahrgenommen und sind Menschen bereit, für eine entschleu-nigte Form des Lebens finanzielle Einbußen hinzunehmen? Vorangegangene Experimente haben zur Beantwortung dieser Frage Grundlagenarbeit geleistet und sind zu dem Ergebnis gekommen, dass zumindest in Teilen der Bevölkerung eine Zahlungsbereitschaft für Entschleunigung vorhanden ist. Zur Bestätigung dieser Hypothese wurden zwei weitere Experimente sowohl in den USA als auch in Deutschland durchgeführt. Die generelle Zahlungsbereitschaft für Entschleunigung konnte bestätigt werden. In ihrer Höhe ist sie jedoch eher als gering einzustufen.

This work investigates the possibility to accelerate a procedure in 4G/LTE systems, known as control channel analysis. The aim is to perform the procedure in real-time on cheap and accessible hardware.An LTE decoder implemented in software is modified to perform the procedure.The modified software is analyzed and profiled. The most time-consuming decoding steps are identified and implemented in hardware description language.The results show an acceleration of the most time-consuming steps of almost 50 times faster compared to implementation in software only. Furthermore, the resource utilization of the hardware design scales linearly with respect to faster decode time, if necessary the acceleration can be increased. However, the results from the profiling and time measurements of the software show that the time requirement is violated by other decoding steps.The thesis concludes that an acceleration in hardware of the most time-consuming steps is possible. However, to satisfy the time requirement further decode steps are required to be accelerated and/or a faster processor can be used.

This work deals with design of communication protocol for data transmission between control computer and computing cores implemented on FPGA chips. The purpose of the communication is speeding the performance demanding software algorithms of non-stream data processing by their hardware computation on accelerating system. The work defines a terminology used for protocol design and analyses current solutions of given issue. After that the work designs structure of the accelerating system and communication protocol. In the main part the work describes the implementation of the protocol in VHDL language and the simulation of implemented modules. At the end of the work the aplication of designed solution is presented along with possible extension of this work.

This study is about high-performing students in mathematics. The purpose of the study was to increase the knowledge about teachers view of adaptions for the high-performing students and how teaching mathematic and its content adapts to these children. The method used in the study was semi-structured in- terviews with 10 teachers in the early years of compulsory school. Data was an- alyzed using Shulmans theory of teacher knowledge base. The result shows three variations of lessons that the participating teachers use. The difference between these lessons was the mindset of how adaptions should be made to the high- performing students in mathematics. It also shows that teachers’ mindset and what guides them in general differs in the three different lessons, also how to work in mathematics. Even though, most teachers wants their students in the same subject area but in different levels of difficulty. The teachers in the study adapts mathematics to the high-performing students’ so the teaching is stimulated and challenging, but how the teachers dose it dif- fers. / Studien handlar om högpresterande elever i matematik. Studiens syfte var att öka kunskaperna om lärares syn på anpassningar för högpresterande elever samt hur matematikundervisningen och dess innehåll anpassades. Studiens undersökningsmetod var kvalitativa semi-strukturerade intervjuer och riktade sig till 10 lärare i grundskolans tidiga år. Den data som samlats in analyserades med hjälp av Shulmans ramverk om lärarkompetens. Resultaten visar tre olika lektionsvarianter som har olika tankesätt om hur anpassningar sker i undervis- ningen till högpresterande elever. Det visar även att det föreligger stora variat- ioner i hur lärare tänker och vad som styr dem i undervisningen, dessutom råder det skillnad i val av arbetssätt. De flesta lärare förespråkar att de vill ha alla ele- ver inom samma ämnesområde men på olika nivåer. Sammantaget gör lärarna anpassningar för att de högpresterande eleverna ska få en stimulerande och utmanade undervisning, men hur anpassningarna sker skiljer sig mellan lärarna.

Die vorliegende Ausgabe beschäftigt sich mit dem Thema „Beschleunigung und Entschleunigung – Eine empirische Untersuchung der Zahlungsbereitschaft für Entschleunigung“. Die allgemeine Beschleunigung der Lebensbereiche des Menschen zieht zunehmend negative ökonomische, soziale und ökologische Konsequenzen nach sich. Um diesem Trend entgegen zu wirken, wird die Strategie der Entschleunigung immer mehr zum Gegenstand wissenschaftlicher Betrachtungen. Wird die Notwendigkeit eines entschleunigten Lebenswandels jedoch von der Bevölkerung wahrgenommen und sind Menschen bereit, für eine entschleu-nigte Form des Lebens finanzielle Einbußen hinzunehmen? Vorangegangene Experimente haben zur Beantwortung dieser Frage Grundlagenarbeit geleistet und sind zu dem Ergebnis gekommen, dass zumindest in Teilen der Bevölkerung eine Zahlungsbereitschaft für Entschleunigung vorhanden ist. Zur Bestätigung dieser Hypothese wurden zwei weitere Experimente sowohl in den USA als auch in Deutschland durchgeführt. Die generelle Zahlungsbereitschaft für Entschleunigung konnte bestätigt werden. In ihrer Höhe ist sie jedoch eher als gering einzustufen.

No description available.