Il y a presque dix ans que l'accélération de l'expansion de l'Univers a été mise en évidence grâce aux observations des supernovae de type Ia et du fonds diffus cosmologique. Cette découverte a changé notre compréhension du contenu énergétique de l'Univers puisque pour expliquer une telle accélération, une composante supplémentaire de matière (effective ou non) est nécessaire et contribue à hauteur de 70%. Cette dernière est appelé "énergie noire". Elle affecte aussi bien les mesures de distance, que la croissance des sur-densités de matières primordiales qui donnent naissance aux structures. Les principales sondes sensibles à ces deux dernières quantités sont les supernovae de type Ia, les amas de galaxies, les lentilles gravitationnelles, et les oscillations acoustiques des baryons (BAO). Afin de contraindre précisément les modèles théoriques (Constante Cosmologique, modification de la théorie de la relativité générale par exemple) qui tentent de déterminer la nature de l'énergie noire, l'observation de chacune de ces quatre sondes est indispensable. Le niveau de précision sur la mesure des paramètres des modèles d'énergie noire requis est tel qu'une nouvelle génération d'instruments va voir le jour dans les années à venir avec notamment le télescope LSST (Large Synoptic Survey Telescope). Le télescope LSST dont le miroir primaire fait 8.4 mètres de diamètre, produira un sondage couvrant la moitié du ciel observable dans 6 bandes photométriques pendant 10 ans. Sa caméra sera la plus grosse caméra jamais construite dans le monde avec un plan focal de 3.2 milliards de pixels. Cette thèse présente à la fois un aspect expérimental et phénoménologique. Le travail présenté porte tout d'abord sur l'élaboration du banc d'étalonnage de la caméra de LSST, et des premières mesures optiques validant le schéma de principe du banc. Nous présenterons ensuite la simulation des BAO dédiée à LSST tentant de prédire à quelle précision les paramètres d'énergie noire pourront être contraint. L'accent est mis sur la production d'un catalogue photométrique de galaxies simulé ainsi que sur une méthode de calcul des redshifts photométriques. La validation de la méthode grâce à des données spectro-photométriques du CFHTLS est également présentée.

This thesis describes an investigation into the suitability of complementary metal oxide semiconductor (CMOS) active pixel sensor (APS) devices for scientific imaging applications. CMOS APS offer a number of advantages over the established charge-coupled device (CCD) technology, primarily in the areas of low power consumption, high-speed parallel readout and random (X-Y) addressing, increased system integration and improved radiation hardness. The investigation used a range of newly designed Test Structures in conjunction with a range of custom developed test equipment to characterise device performance. Initial experimental work highlighted the significant non-linearity in the charge conversion gain (responsivity) and found the read noise to be limited by the kTC component due to resetting of the pixel capacitance. The major experimental study investigated the contribution to dark signal due to hot-carrier injection effects from the in-pixel transistors during read-out and highlighted the importance of the contribution at low signal levels. The quantum efficiency (QE) and cross-talk were also investigated and found to be limited by the pixel fill factor and shallow depletion depth of the photodiode. The work has highlighted the need to design devices to explore the effects of individual components rather than stand-alone imaging devices and indicated further developments are required for APS technology to compete with the CCD for high-end scientific imaging applications. The main areas requiring development are in achieving backside illuminated, deep depletion devices with low dark signal and low noise sampling techniques.

In this work, we analyze the data from 1.5 m telescope of Tubitak National Observatory (TUG) for two objects V2275 Cyg and RW UMi. After applying aperture and PSF photometry to the CCD data, we derive the light curve of the objects. Also we apply discrete Fourier transform and Scargle time series analysis to obtain power spectrum and search for periodicities in their power spectra in which both systems show interesting properties. We discover large variations in V2275 Cyg due to irradiation effects on the secondary, with an orbital period Porb = 0.316&plusmn / 0.007 day. We also detect a very short orbital period for RW UMi Porb = 1.96&plusmn / 0.073h and also a spin period Pspin = 1.29&plusmn / 0.036h in the presence of several beat frequencies. These results (if con&amp / #64257 / rmed) lead us to say that RW UMi can be an intermediate of polar system.

Zugl.: Tübingen, Univ., Diss., 2009

Made available in DSpace on 2014-06-11T19:22:25Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-01-18Bitstream added on 2014-06-13T18:08:13Z : No. of bitstreams: 1 galindo_jrf_me_prud.pdf: 1101121 bytes, checksum: fe484a202d77b0a31f93d9a5e1d4b42a (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Desde o advento dos primeiros satélites de Sensoriamento Remoto, vários são os estudos desenvolvidos com o intuito de utilizar as imagens produzidas por estes sensores para fins cartográficos. Apesar das imagens de baixa e média resolução não possuírem a precisão requerida para aplicações cartográficas em escalas grandes, existem vantagens como: serem imagens multiespectrais, possuírem periodicidade e menores custos para a sua aquisição, quando comparadas com as obtidas através dos tradicionais levantamentos aerofotogramétricos. Uma melhoria presente nos satélites de alta e média resolução é a capacidade de visada off nadir, o que permite à formação de pares estereoscópicos e a reconstrução 3D da cena imageada, a geração de modelos digitais de elevação (MDE) e a produção de imagens ortorretificadas, dentre outros produtos. Com os primeiros pares estereoscópicos adquiridos pelo sensor HR-CCD (High Resolution Charge-Coupled Devices) do CBERS-2 (2004), surgiu a possibilidade de realizar estudos objetivando a geração de produtos cartográficos a partir desses estereopares... / Since the advent of the first Remote Sensing satellites, many studies have been developed with the intention of using the images produced by these sensors for cartographic purpose. Although these images of the average resolution do not possess the accuracy required for cartographic applications in big scales, their advantages include being multispectral, periodic repetition of acquisition, and lower cost when compared to images obtained through traditional aerial photogrammetric surveys. An improvement present in medium and high resolution satellites is their off nadir capacity, which allows 3D reconstruction based on stereoscopy, the generation of digital elevation models (DEM) and the production of orthorectified images, among others products. With the first stereoscopic pairs acquired by the CBERS-2 (2004) HR-CCD (High Resolution Charge-Coupled Device) sensor, the possibility now exists of realizing studies whose goal is generating cartographic products from these stereo pairs. Within this context, this work evaluated the geometric quality of a CBERS-2 HR-CCD stereo pair making use of the DLT (Direct Linear Transformation) mathematical model and Polynomial-Based Pushbroom model, available from the Leica Photogrammetry Suite (LPS) digital photogrammetry system by Leica Geosystems, classifying them in accordance with the Cartographic Accuracy Standards... (Complete abstract click electronic access below)

L’objectif de ce travail est d'étudier expérimentalement la formation du capillaire durant le perçage et le soudage par faisceau laser, et de développer une simulation numérique permettant de reproduire la dynamique de formation et d'évolution du capillaire. Nous avons fait le choix d’utiliser comme matériau test le Zinc, en raison de ses propriétés thermodynamiques. Afin de simplifier le problème, nous avons étudié dans un premier temps le mécanisme de perçage. Deux méthodes expérimentales ont été utilisées pour caractériser l'évolution de la géométrie du capillaire : La méthode DODO (Direct Observation of Drilled hOle ) permet de visualiser le capillaire après perçage pour différentes durées et la méthode Zn-Quartz permet d’observer directement son évolution temporelle par camera rapide à travers une lame de quartz. Puis nous avons utilisé cette évolution pour mettre au point une simulation du mécanisme de perçage. Après avoir étudié le dépôt de puissance à l’intérieur d’un capillaire en tenant compte des réflexions multiples et estimé l'importance de la perte d'énergie et de matière lors du processus, nous avons développé une simulation en utilisant le logiciel Comsol Multiphysics couplant l'équation thermique, l'équation de Navier Stokes et prenant en compte le déplacement du métal fondu sous l’action de la pression de recul. Dans ce cas, on observe la formation d’un bourrelet important au bord du trou et une augmentation de la profondeur du capillaire. Ensuite nous avons étudié la formation du capillaire durant le soudage laser, c'est-à-dire avec déplacement de la source. A partir des techniques mises en œuvre pour l’étude du perçage nous avons obtenu l’évolution de la forme du capillaire dans le cas du soudage Zn/Quartz. Nous avons réalisé une simulation relativement simple en supposant la géométrie et la température du capillaire connues a priori. Nous avons constaté qu’un modèle simple, modélisant uniquement les transferts thermiques par conduction, permet de bien simuler la forme de la zone fondue pour les couples Zn/Zn et Zn-quartz. / The aim of the present work is to study experimentally the formation of the capillary during the drilling and welding by laser beam and to develop the numerical simulation which allows following the dynamics and the evolution of the keyhole. The zinc was chosen as a test material because its thermodynamical properties are well known. To simplify the problem, in the first place the drilling mechanism was studied. Two experimental methods were used to characterize the evolution of the keyhole: the Direct Observation of Drilled Hole method, which allows the visualization of the keyhole after the application of laser pulses of different durations, and Zn-Quartz method, which allows the direct observation of keyhole evolution with CCD camera through the layer of quartz. Then, the information on keyhole evolution was used to develop the simulation of drilling mechanism. After studying the beam power deposition inside the capillary with taking in account the multiple photon reflections, and after estimation of the energy and matter loss during the process, we developed the simulation with FEM software COMSOL Multiphysics, which contains coupled heat transfer, fluid flow and free surface problem allowing considering the effect of recoil pressure on liquid phase ejection. We could observe the formation of an important bolster surrounding the keyhole and the increase of keyhole depth with time. Next, we studied the formation of the keyhole during the laser welding, in other words, during the displacement of the heat source. Using the same technique that was developed for laser drilling, we have obtained the information on keyhole evolution during zinc-quartz welding. We have created the simple simulation, where keyhole temperature and profile were considered as known a priori. We have stated that this model, which takes in account only conduction heat transfer problem, allows to reproduce well the shape of the melted zone both for zinc-zinc and zinc-quartz couples

This thesis studies the optimization of diagnosis defects of the photovoltaic cells in the darkroom by the help of new operating software for the used CCD camera. First the present situation and the possible solutions are analyzed. Then the attention is paid to the theory of light-sensitive CCD sensors, their construction, their principles of operation and the theory of scanning images. The thesis also focuses on the analysis of the function of the operating libraries which were provided by the equipment producer. The key part is the development of the application for the camera G2-3200 of the "Moravske pristroje" company which significantly accelerates the work with the camera in the darkroom.

Tato Diplomová práce je zaměřena na odstranění šumu ze snímků získaných pomocí Transmisního elektronového mikroskopu. V práci jsou popsány principy digitalizace výsledných snímků a popis jednotlivých šumových složek, které vznikají při digitalizaci snímků. Tyto nechtěné složky ovlivňují kvalitu výsledného snímku. Proto byly vybrány filtrační metody založené na minimalizaci totální variace, jejichž principy jsou v této práci popsány. Jako referenční filtrační metoda byla vybrána filtrace pomocí Non-local means filtru. Tento filtr byl vybrán, jelikož v dnešní dobře patří mezi nejvíce využívané metody, které mají vysokou účinnost. Pro objektivní hodnocení kvality filtrací byly použity tyto hodnotící kritéria – SNR, PSNR a SSIM. V závěru této práce, jsou všechny získané výsledky zobrazeny a jsou diskutovány účinnosti jednotlivých filtrační metod.

During my master thesis I became familiar with ion imaging and velocity map imaging (VMI) techniques in experiments with molecular beam. My major contribution was writing a computer program for data acquisition and pre-analysis. The program features initial filtering of the data, improving significantly signal to noise ratio. Non-trivial effort was required to make the program compatible with three different CCD cameras implemented on different experiments in the laboratory. I have also simulated ion trajectories in VMI and wrote a program code to imulate VMI image distortions due to imperfections in apparatus geometry. These programs will be useful in aligning and tuning the apparatus. Finally, I wrote a program for data manipulation and conversion to formats compatible with various data analysis programs available in the laboratory. All the above programs I have tested by measurements of 243 nm photodissociation of HBr molecules.

Antibiotic resistance is now a recognized problem in global health. In attempts to find solutions to detect bacteria causing antibiotic resistance we turn to technological solutions that are miniaturized, portable and cheap. The current diagnostic procedures cannot provide correct information outside laboratory settings, at the point-of-care, within necessary time. This has led to ineffective treatment of urinary tract infections causing recurrent infections and multi-drug resistant bacteria to spread. The bacteria genes show which antibiotic that is required to eliminate disease and spread of resistance. Hence, the solution would be to perform nucleic acid testing at the point-of-care. By using new DNA amplification methods it is possible to miniaturize the diagnostic test to a so-called Lab-on-a-chip. These solutions would enable sample-in-results-out capability of the system at the point-of-care. For this to work one of the most important factors is fluorescent signal read-out from DNA amplification products. In this project the design parameters of such a read-out device was investigated with focus on image sensor sensitivity and device integration. During the project it was found that a low-cost commercial image sensor could be used to record images of a (3.76 x 2.74 mm2) micro well array of nanoliter sized PCR chambers. Different imaging artifacts appearing during sample partitioning were observed, distance dependency between sensor surface well array was investigate, and finally the image sensor function was compared to a fluorescent microscope.