Syftet med denna undersökning är att genom en komparativ studie med utgångspunkt i teorier om dialogicitet, hyptertextualitet och transformation, analysera förekomsten av grekisk mytologi i The Lightning Thief (2005) – vilken påverkan dessa har och hur de tar sig uttryck i Riordans roman. De grekiska myterna i The Lightning Thief har jämförts med de som beskrivs i Grekisk Mytologi (1977) av Giovanni Caselli och Michael Gibson, En introduktion till grekisk mytologi (1989) av David Bellingham, samt Ovidius Metamorfoser (8 e.Kr.). Resultaten visar att de grekiska myterna har en förklarande funktion och agerar inspiration för Riordans egen berättelse. Likväl har författaren flyttat över de grekiska gudarna i myterna till The Lightning Thief och utgått från dem som modeller för framställningen av hans egna karaktärer. Dock har Riordan anpassat och moderniserat både myterna och gudarna för att de ska passa in i den värld som författaren själv har skapat.

La propagation des impulsions laser ultra brèves dans l’air se fait sous la forme de structures d’une centaine de micromètres de diamètre appelées filaments, qui ont entre autres les propriétés d’être autoguidées, de se propager sur plusieurs centaines de mètres, de générer un continuum de lumière blanche, etc. Ces propriétés originales trouvent de nombreuses applications dans le domaine de la télédétection des polluants par mesures lidar, le déclenchement et le guidage de la foudre par laser, le LIBS à distance, etc.Au cours de mon travail de thèse, nous avons mené de nombreuses expériences de laboratoire et sur terrain dans le cadre du projet Tera mobile. Nous avons en particulier étudié la géométrie de la filamentation, sa robustesse dans une région de turbulence étendue, la propagation verticale d’un faisceau d’impulsions ultra brèves dans un régime multi joules, et des applications atmosphériques de la filamentation. Nous avons par exemple caractérisé la distribution angulaire de l’émission conique dans le visible et dans l’ultraviolet. Nous avons également prouvé que la turbulence atmosphérique n’est pas un facteur limitant de la propagation des filaments qui arrivent même à garder leurs propriétés spectrales nécessaires aux applications atmosphériques. Enfin nous avons illustré une méthode de déclenchement et de guidage de foudre par laser et réalisé une expérience de condensation de gouttelettes d’eau assistée par laser en laboratoire ainsi que dans une atmosphère réelle. / Ultrashort laser pulses propagate in the air in the form of structures of one hundredmicrons of diameter called “filaments”, which have the properties of self-guiding, propagatingfor hundreds of meters, white light generation, etc. These original properties find severalapplications in the domain of remote sensing of pollutants by non-linear Lidar measurements,lightning control, remote LIBS, etc.During my PhD work we have performed several laboratory experiments and field campaignwithin the context of Teramobile project. In particular we have studied the geometry offilamentation, its robustness in an extended region of turbulent air, the propagation ofultrashort pulses beam in multijoules regime, and atmospheric applications of filamentation.For example, we have characterized the angular distribution of the conical emission in thevisible and ultraviolet spectral bands. In another series of experiments, we have proved thatatmospheric turbulence is not a limiting factor of filaments propagation, which also keep theirspectral properties useful for atmospheric applications. Finally, we have illustrated a methodof laser triggering and guiding of lightning and realized laser induced condensation of waterdroplets in laboratory as well as in a reel atmosphere.

The research presented in this thesis is situated within an interpretivist paradigm. Within this paradigm, a qualitative case-study research approach was adopted. This seemed most appropriate in my research project since the main focus is on elicitation of prior knowledge and incorporation of such knowledge into 'hands-on' and 'minds-on' practical activities with a view to improving conceptual development. For the purposes of this research project, I designed an interactive teaching and learning unit in electrostatics as an attempt to put into practice a learner-centred approach. This approach, in my view, is in line with the new curriculum in South Africa. The emerging central theme of this thesis is the notion of active participation by learners during teaching and learning. This study was carried out over a period of two years and involved my grade 9 learners, who participated voluntarily. The research process documented in this thesis has been conceptualised into two phases. Phase one was concerned with the elicitation of learners' prior knowledge around lightning. In phase two, learners were engaged in 'hands-on' and 'minds-on' practical activities, and key concepts were identified to ensure conceptual development. The data was collected using a variety of data collection tools, namely: focus group interviews, follow-up whole-class semi-structured interviews, worksheets, videotaped lessons and photographs. The analysis of data revealed that learners come to class with prior knowledge concerning lightning. Within this prior knowledge it was found that there were both ‘scientific’ and ‘non-scientific’ concepts. The identification of key concepts during practical activities was found to be very useful in promoting learning. However, the incorporation of prior knowledge into practical activities posed a challenge and needs further research. iv This research study also highlights some insights into some of the complexities of elicitation and incorporation of learners' prior knowledge, and conceptual development in science classrooms. It also demonstrates the challenges and possibilities during teaching and learning as well as the realities of the demands of the new curriculum and OBE in South Africa, in particular, in historically disadvantaged schools

This project was made by student from UmeåUniversity and a request from the universityETH in Zürich, Switzerland. In this research project the electrical strengthof different natural gases and mixtures was investigated, and the aim was to finda gas or gas mixture with a natural origin or strongly attaching gases that couldreplace SF6 (Sulfur Hexafluoride). The gases were tested with breakdown experiments,one of those test was called lightning impulse breakdown test. The mainpart of this project was to investigate triggered spark gaps, which could be used inlightning impulse breakdown test. These spark gaps were made in a previous thesis,but have proved to not be reliable, therefore an investigation was needed. In thelab, a breakdown test setup, made up of a rectifying circuit and a transformer, wasused. In this project voltages up to 140kV were used. The two main parts of theproject were the spark gap unit and circuit analyzing and the spark gap characterization.These two parts contained test to see if the spark gap worked as it shouldor if there were any problems with it. The results from the tests showed that therewere problems with the spark gap, but these problems could be corrected or avoidedthrough controls of the spark gap before use.

No description available.

Dans une vision de transports plus économiques, l’apport des matériaux composites est une solution technologique importante pour l'industrie aéronautique, même si cela ouvre de nouvelles questions de compatibilité électromagnétique sur l’ensemble du système et nécessite l’utilisation d’outils de simulation adaptés. Cette thèse présente l’évaluation de cette mutation technologique vis-à-vis de la problématique foudre. Les méthodes conventionnellement utiliséesdans le cadre de la modélisation électromagnétique en 3D des effets indirects de foudre sur les aéronefs s’avèrent limitées car la prise en compte de toutes les particularités géométriques ouphysiques des dispositifs étudiés est difficile. Dans le cadre du Projet PREFACE (PRojet d’ÉtudeFoudre sur Avion Composite plus Électrique), ces travaux de thèse proposent d’évaluer desméthodes de modélisation non conventionnelles dans le domaine de l’aéronautique et enparticulier la méthode intégrale de recherche de schémas électriques équivalents localisés (PEEC).Une maquette composite de type caisson a été conçue et réalisée afin de représenter la structureminimale d’une section de fuselage, incluant du câblage intérieur. Des mesures ont été effectuéespour étudier et évaluer les mécanismes de couplages électromagnétiques entre les structurescomposites et les dispositifs internes après injection d’un courant, en particulier dans le cadre dela problématique de l’agression foudre. Une comparaison avec des modélisations PEEC (codeInCa3D) dans différentes configurations a permis avec succès de comprendre les phénomènesphysiques mis en jeu. Les avantages de cette approche apparaissent très nettement quand il s’agitde prendre en compte les différents paramètres dimensionnant pour déterminer la répartition descourants sur la structure et sur les câbles connectés à l’intérieur. Ceci permet de formuler desrègles générales de conception des protections des équipements internes qui peuvent êtreappliquées sur les avions à moindre coût. / For economic reasons, the use of composite materials seems to be a valuable solution foraeronautic industries, even if their efficiency concerning the electromagnetic compatibility of on-board systems requires some studies. For that, the use of adapted simulations tools isunavoidable. This thesis presents the evaluation of this technological mutation towards lightningissue. The methods conventionally used in the context of 3D electromagnetic modeling oflightning’s indirect effects on aircrafts prove to be restricted because it is difficult to take intoaccount all geometric or physical particularities of devices. In the framework of the PREFACEproject (a national project devoted to the study of Lightning Indirect Effects (LIE) on moreelectric and composite aircrafts), this thesis proposes to evaluate unconventional modellingmethods in aeronautics, in particular, the integral method PEEC (Partial Element EquivalentCircuit). A composite model like caisson has been designed and constructed to represent theminimal structure of fuselage section, including inside wiring. Measurements were performed inorder to study and evaluate the electromagnetic coupling mechanisms between compositestructures and internal devices after a current injection, particularly, in the context of lightningaggression problem. A comparison with PEEC modelling (code InCa3D) in differentconfigurations has enabled successfully to understand the physical phenomena involved. Theadvantages of this approach appear very clearly when it comes to taking into account thedifferent sizing parameters in order to determine the current distribution on the structure and thecables connected to the interior. This will allow formulating general rules to concept theprotections of the internal equipments, which can be applied on aircrafts at a low

O Sistema ALIS (Atmospheric Limb Imaging System), do Instituto Nacional de Pesquisas Espaciais (INPE) em São José dos Campos, a bordo do satélite EQUARS (Equatorial Atmosphere Research Satellite), tem como objetivo observar três fenômenos ópticos da atmosfera na direção horizontal (Limb) do satélite em órbita: a aeroluminescência, os relâmpagos e os sprites. Os sprites são fenômenos luminosos verticais que ocorrem na mesosfera e ionosfera inferior de coloração vermelho-alaranjada e o seu estudo é de grande importância devido à influência que exerce sobre o clima terrestre, juntamente com demais fenômenos. O objetivo deste projeto é a criação de um software capaz de identificar relâmpagos e sprites capturados por meio de um CCD e, através desta identificação, decidir quais imagens devem ser guardadas para posterior envio e quais devem ser descartadas. Estudos preliminares demonstram que por meio de técnicas de segmentação de imagem utilizando-se contorno ativo (que poderiam ser empregados em uma posterior análise de formas) e compactação por meio de wavelets é possível reconhecer, localizar e guardar aqueles fenômenos que forem de interesse. / THe Atmospheric Limb Imaging System (ALIS), from Brazilian National Institute for Space Research (INPE), embedded in the Equatorial Atmosphere Research Satellite (EQUARS) aims at searching for three optical phenomena along the Earth’s Limb: airglow, lightning and sprites. Sprites are vertical luminous phenomena that occur in the mesosphere and inferior ionosphere of red-orange coloration. The gathering of knowledge on sprites is of great importance do to their influence over the terrestrial climate, together with the other phenomena. The objective of this project is to create a software tool capable of identifying lightnings and sprites captured by a CCD camera. From this identification the tool can decide which images should be kept for subsequent upload and which should be discarded. Preliminary studies have demonstrated that through image segmentation techniques with active contour (that could be employed in a subsequent shape analysis process) and wavelet-based compression methods it is possible to recognize, locate and preserv those phenomena of interest.

La foudre est un phénomène naturel aléatoire impactant un avion de transport civil en moyenne une fois toutes les 1500 heures de vol. Les forts courants et impulsionnels pouvant parcourir la structure d'un aéronef peuvent induire des contraintes physiques aux conséquences sérieuses en ce qui concerne la sûreté. En particulier, quand un assemblage est parcouru par un courant de type foudre, des champs électriques ainsi des densités d'effet Joule importants peuvent engendrer différents phénomènes de décharge. Le risque d'étincelage est particulièrement critique au niveau des réservoirs de carburant, et différentes technologies de protection et procédures de certification sont employées pour maitriser ce risque. Les résultats expérimentaux laissent penser que la formation de ces décharges est due aux résistances électriques localisées aux interfaces entre les différentes pièces des assemblages. Le but de cette thèse a été de modéliser les phénomènes qui se produisent à une échelle microscopique au niveau de telles résistances de contact soumises à de forts courants impulsionnels de type foudre. / Lightning is a natural hazardous event that strikes a civil aircraft on average once per 1500 hours of flight. The corresponding high and impulsive currents that may flow along the structure of the aircraft can generate physical constraints with major consequences regarding safety. In particular, when a fastened assembly is crossed by a lightning current, important electric fields and Joule power densities may give birth to a variety of discharge phenomena. The sparking risk is particularly critical in fuel tanks, and different lightning protection technologies and certification procedures are employed to face it. The ignition of discharges is believed to be mostly due to the local electrical resistance at the interfaces between the parts of the assemblies. The aim of this thesis was to model to phenomena that occur at a microscopic scale of such contact resistances subject to high and impulsive currents.

The purposes of this study were to explore the current scenario of interscholastic athletics in regards to the existence and enforcement of lightning safety policies applied to athletic outdoor activities, and to identify the common practices related to lightning safety currently utilized. The results showed that 87.2% of the respondents (N=804) have lightning safety policies. However, only 90.3% of the respondents who have lightning safety policies actually enforce them. It seems that during practices coaches are most commonly responsible for making the decision to stop/resume activity, and that during games athletic directors are most commonly making the call. However, almost one third of the respondents (N=804) do not have a clear designation as to who makes the decision. A less than desirable percentage of respondents reported frequent use of a lightning detection system, availability of shelters for spectators, and posted lightning policy in facilities. Only 7.8% of the respondents indicated that all athletic coaches and staff receive lightning safety training. The results also showed that more experienced administrators were more likely to have and enforce lightning safety policies, and employ lightning safety best practices. This study provides high school athletic administrators and principals with relevant information that can be used to support their decision to adopt and enforce lightning safety policies for interscholastic athletic activities.

This thesis deals with the description of artificial light sources, that use light-emitting diodes for their operation. Further down, the parameters of LEDs and their emissions are detailed. The work follows with the characterization of principles of LED power regulation. In the practical section, an example of one of the possible LED light source topologies, is designed. The offered solution includes the options to manually and automatically regulate the chromaticity of emitted light. Functionality of the solution was verified experimentally.