In nature, many of the flapping wings and fins in swimming and flying animals have various degrees of flexibility with strong and coupled solid-fluid interactions between the structure and the fluid. In most cases, the wing structure, the flow and their interactions are complex. This thesis experimentally investigates a ‘simple’ fluid-flexible foil interaction problem: flow generated by a pitching foil with chordwise flexibility. To explore the effect of flexibility on the flow, we study the flow generated in quiescent water (the limiting case of infinite Strouhal number) by a sinusoidally pitching rigid symmetrical NACA0015 foil to which is attached a 0.05 mm thick chordwise flexible polythene flap at the trailing edge. The chordwise length of flap is 0.79 c, where c = 38 mm is the chord length of the rigid foil; span of the foil and flap is 100 mm. Detailed particle image velocimetry (PIV) and flow visualization measurements have been made for twelve cases, corresponding to three pitching amplitudes, ±10◦,± 15◦, ±20◦, and four frequencies, 1, 2, 3 and 4 Hz for each amplitude. For most of these cases, a narrow coherent jet aligned along the center-line, containing a reverse B’enard–K´arm´an vortex street, and a corresponding unidirectional thrust are generated. This thrust is similar to the upward force generated during hovering, but motion of our foil is much simpler than the complex wing kinematics found in birds and insects; also the thrust generation mechanism seems to be different. In our case, the thrust is from a coordinated pushing action of the rigid foil and the flexible flap. Control volume analysis reveals the unsteady nature of thrust generation. In this intricately coupled flow generation problem, chordwise flexibility is found to be crucial in producing the coherent jet. In this thesis, we explore in detail the physics of jet flow produced by the foil with a flexible flap, and identify the importance of flexibility in flow generation. Flap motion ensures appropriate spatial and temporal release of vortices, and also imparts them convective motion, to obtain the staggered pattern that produces the jet. To describe the fluid-flap interaction, we conveniently characterize the flap through a non-dimensional stiffness, ‘effective stiffness’ (EI)∗ of the flap, that captures the effects of both the flap properties as well as the external forcing. With the same flap by changing the pitching parameters, we cover a fairly large (EI)∗ range varying over nearly two orders of magnitude. However, we observed that only moderate (EI)∗ (~0.1 - 1) generates sustained narrow, orderly jet. We provide thrust estimates useful for the design of flapping foil thrusters/propulsors. Although this study has only indirect connections with the hovering in nature, it may be useful in understanding the role of flexibility of bird and insect wings during hovering. In contrast, a foil with a rigid trailing edge produces a weak jet whose inclination changes continually with time. This meandering is observed to be random and independent of the initial conditions over a wide range of pitching parameters.

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5A Abstract This work gives the analysis of iconographic elements which are found on five gold foils. These foils depict two figures which look at each other from their profile. Foils were found in the foundations of the chieftain house in Lofot's islands in Northern Norway, which is from the Migration to the Viking period. For the reason of analysis the author demonstrates three main groups of gold objects - gold bracteates, gold foils and one medallion. On these objects we can find a pair of two figures and these objects were found in Scandinavia. The author presents here the context of such finds, iconographic elements and academic interpretations of the depiction. Author compares the elements such as type of foil, appearance of eyes, posture of man and woman, their dress and haidress with 91 foils from Scandinavia, and also with bracteates and other objects. She notices the partial concordance among these elements and the other objects and she seeks the iconographic essence and function of each foil from Borg which is later confronted with the theories of the influence of religion. Because of lack of attributes on the foils, the author's assumption is that there is no general depiction of gods on the foil. On the other hand, each foil has its own story showing people from their common life. According to...

De nouveaux radio-isotopes pour la médecine nucléaire peuvent être produits par des accélérateurs de particules. C'est l'un des buts d'Arronax, un cyclotron de hautes énergies - 70 MeV - et hautes intensités - 2*350 µA - installé à Nantes. Une liste d'émetteurs b- - 47Sc, 67Cu - b+ - 44Sc, 64Cu, 82Sr/82Rb, 68Ge/68Ga - et a - 211At - à étudier en priorité a été établie. Parmi ceux là, le 47Sc et le 67Cu présentent un intérêt en thérapie ciblée. L'optimisation de leurs productions nécessite la bonne connaissance de leurs sections efficaces, mais aussi de celles de tous les contaminants créés. Nous avons lancé sur Arronax un programme de mesures de sections efficaces utilisant la technique des Stacked-foils. Elle consiste en l'irradiation simultanée d'un groupe de feuilles - cibles, moniteurs et dégradeurs - et la mesure par spectro-gamma de la production d'isotopes. Les moniteurs permettent un contrôle des pertes de faisceau tandis que les dégradeurs en diminuent l'énergie. Nous avons étudié les réactions natTi(p,X)47Sc et 68Zn(p,2p)67Cu. Les cibles étant respectivement des feuilles de natTi - achetées chez Goodfellow - ou des électrodépositions sur Ag de 68Zn enrichi. Nous les réalisons nous même ainsi que la séparation chimique des isotopes de Cuivre et de Gallium indispensable avant de procéder au comptage gamma. Les sections efficaces de plus de 40 réactions ont ainsi été obtenues sur l'intervalle de 18 MeV à 70 MeV. Une comparaison avec le code Talys est systématiquement faite, et plusieurs paramètres des modèles théoriques étudiés. Nous montrons qu'il est impossible de reproduire avec exactitude toutes les sections efficaces à partir d'un seul jeu de ces paramètres.

Cadmium Telluride (CdTe) is a leading thin film photovoltaic (PV) material due to its near ideal bandgap of 1.45 eV and its high optical absorption coefficient. The typical CdTe thin film solar cell is of the superstrate configuration where a window layer (CdS), the absorber (CdTe) and a back contact are deposited onto glass coated with a transparent electrode. Substrate CdTe solar cells where the above listed films are deposited in reverse are not common. In this study substrate CdTe solar cells are fabricated on flexible foils. The properties of the Molybdenum back contact, Zinc Telluride (ZnTe) interlayer and CdTe absorber on the flexible foils were studied and characterized using X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM). Substrate curvature and film flaking was observed during the fabrication as a result of differences in thermal expansion coefficients between the substrate and the deposited films, and also due to impurity diffusion from the foil into the film stack. In order to overcome this problem diffusion barriers where used to eliminate contamination. Silicon dioxide (SiO2), silicon nitride (Si3N4) and molybdenum nitride (MoxNy) were used as such barriers. Electrical characterization of completed devices was carried out by Current-Voltage (J-V), Capacitance-Voltage (C-V) and Spectral Response (SR) measurements. Roll-over was observed in the first quadrant of J-V curves indicating the existence of a back barrier due to a Schottky back contact. The formation of non-rectifying contact to p-CdTe thin-film is one of the major and critical challenges associated with the fabrication of efficient and stable solar cells. Several materials (ZnTe, Cu, Cu2Te, and Te) were studied as potential candidates for the formation of an effective back contact.

In this essay I have chosen to take a closer look at gold figure foils (Swedish “guldgubbar”), find their context and analyze it. I have analyzed some earlier studies about gold figure foils that were found in Scandinavia. The focus of my study is based on the locations of the findings. Another important aspect is to discuss if the encountered gold figure foils that were folded and cut looked like that due to intentional motives or not. My conclusion is that when it comes to the locations of the findings they are mostly found in houses irrespective of if it´s in a posthole, wall or house foundation. The other conclusion is that the gold figure foils could have intentionally been manipulated before they ended up in the ground.

Made available in DSpace on 2014-10-09T12:54:46Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:07:31Z (GMT). No. of bitstreams: 1 12782.pdf: 5810159 bytes, checksum: 89e60520369008e4796ebb925cf90bdb (MD5) / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN/CNEN-SP

Made available in DSpace on 2014-10-09T12:33:40Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:05Z (GMT). No. of bitstreams: 0 / Este trabalho apresenta os resultados dos valores de fluxo de nêutrons obtidos a partir da implantação de uma armadilha de nêutrons no núcleo do Reator IPEN/MB-01. Foram analisadas várias configurações de armadilhas implantadas no núcleo do reator IPEN/MB-01 de forma a se eleger a armadilha mais eficiente. Para a caracterização energética, foram irradiados no centro da armadilha de nêutrons, detetores de ativação de vários materiais diferentes (Au, Sc, In, Ti, Ni). As respectivas espectrometrias gama desses elementos após a irradiação com e sem cobertura de cádmio, forneceram valores experimentais das taxas de reação nuclear (atividade de saturação) por núcleo alvo e as respectivas incertezas que servem de entrada ao código SANDBP que calculou o espectro de energia dos nêutrons no centro do Flux-Trap em 50 grupos de energia, utilizando-se dos espectros de entrada calculados na posição de irradiação (centro do \"Flux Trap\") por códigos de Física de Reatores. Os resultados obtidos constataram um aumento do fluxo de nêutrons térmico no centro da armadilha da configuração 203 em relação a configuração sem armadilha (padrão) da ordem de 350% sem contudo haver a necessidade de se aumentar a potência do reator. Foram também efetuadas comparações entre os espectros desdobrados obtidos pelo SANDBP, em relação aos calculados pelos códigos MCNP-4C e XSDRNPM. A caracterização espacial do fluxo de nêutrons térmicos é feita com folhas de ativação na forma de uma liga infinitamente diluída em massa de 1% de Au e 99% de Al em alguns pontos internos da configuração 203 (axialmente ao Flux Trap\" e adjacências radiais) e os resultados mostraram um aumento significativo da magnitude de seus valores quando comparados a configuração padrão retangular. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:54:46Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:07:31Z (GMT). No. of bitstreams: 1 12782.pdf: 5810159 bytes, checksum: 89e60520369008e4796ebb925cf90bdb (MD5) / Muitos parâmetros nucleares são obtidos através da espectrometria gama de alvos irradiados no núcleo de um reator de pesquisa e este é o caso das folhas de ativação que possibilitam através da medida da atividade radioativa nelas induzidas, determinar o fluxo de nêutrons no local onde foram irradiadas. O nível de potência de operação do reator é um parâmetro diretamente proporcional ao fluxo médio de nêutrons no núcleo. Esse trabalho objetiva determinar a potência de operação do reator através da medida da distribuição espacial do fluxo de nêutrons no núcleo do reator IPEN/MB-01, através da irradiação de folhas de ouro infinitamente diluídas e criteriosamente posicionadas em seu interior. Essas folhas estão dispostas na forma de ligas metálicas em níveis de concentração tais, que fenômenos de perturbação de fluxo, como o fator de auto-blindagem, se tornem desprezíveis. As folhas de ativação possuem somente 1% de átomos de ouro dispersos numa matriz de alumínio contendo 99% deste elemento. As irradiações das folhas foram realizadas com e sem cobertura de cádmio. A total correlação entre fluxo de nêutrons térmico médio obtido pela irradiação das folhas de ativação infinitamente diluídas e a média dos valores digitais das correntes dos canais nucleares de potência 5 e 6 (câmaras de ionização não compensadas - CINC), permitem a calibração dos canais nucleares do reator IPEN/MB-01. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energéticas e Nucleares - IPEN/CNEN-SP

The diploma thesis is focused on preparation of thin and highly flexible ceramic tapes from zirconia with a thickness from 70 to 200 m. The thesis is divided into two parts. The first part presents a literary research that focuses on the properties of zirconium dioxide, the preparation of thin ceramic foils and the evaluation of the mechanical properties of ceramic materials. The second part is experimental. It deals with the preparation of thin ceramic foils from colloidal ceramic suspensions produced by epoxy gel-tape casting method. The suspensions were prepared from zirconium dioxide stabilized by 2 and 3 mol.% of yttrium oxide. The maximum deflection and strength was determined on sintered foils. The maximum biaxial strength of 1806 MPa was achieved for 3Y-PC 75 foils with a thickness of 190 m. The maximum deflection of 10.5 mm at a ceramic foil thickness of 75 m was achieved in a 3-point bend with a support span of 30 mm on 3Y-PC 75 samples. At a support distance of 50 mm, the samples were pushed through the gap without damage. These results indicate excellent mechanical properties of the prepared ceramic foils.