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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Análise da gestão da propriedade intelectual no Departamento de Ciência e Tecnologia Aeroespacial

César Augusto O'Donnell Alván 10 August 2012 (has links)
A presente pesquisa aborda a gestão da propriedade intelectual em uma reconhecida instituição de pesquisa da área de Defesa no Brasil, o Departamento de Ciência e Tecnologia Aeroespacial (DCTA). Ela busca verificar se a estrutura normativa dessa instituição propicia a preservação dos interesses do Estado Brasileiro quanto à gestão da propriedade intelectual. Para isso, investiga aspectos de propriedade intelectual de projetos tecnológicos do DCTA, ocorridos em diferentes épocas, e os confronta com a estrutura normativa atualmente em vigor. Ao final, apesar de reconhecer as dificuldades impostas pela grande amplitude dos interesses do Estado nesse tema, e a consequente imprecisão quanto aos seus limites, os resultados da pesquisa permitem que se conclua que o DCTA efetivamente possui lacunas normativas significativas, que podem dificultar a preservação daqueles interesses, quaisquer que sejam eles.
12

Der Kontrastmittelrückfluss in die Vena cava inferior in der computertomographischen pulmonalen Angiographie als Prädiktor für die 24-Stunden- und 30-Tage-Mortalität bei Patienten mit akuter Lungenarterienembolie

Bailis, Nikolaos 14 April 2023 (has links)
No description available.
13

Anlagestrategien für Pensionsvermögen im Rahmen von Contractual Trust Arrangements

van den Bergh-Mehner, Stefanie 22 December 2011 (has links)
Die vorliegende Arbeit behandelt die Anlage von Pensionsvermögen im Rahmen von Contractual Trust Arrangements. Es wird untersucht, welche Anlagestrategien sich unter Berücksichtigung bilanzieller, verpflichtungs- und vermögensseitiger Rahmenbedingungen zur Anlage von Pensionsvermögen eignen. Anhand eines geeigneten Anlagemodells für Pensionsvermögen und der Durchführung einer stochastischen Simulation wird analysiert, welchen Einfluss unterschiedliche Anlagestrategien auf die Entwicklung des Pensionsvermögens haben. Die Arbeit geht zunächst den Hintergrund der betrieblichen Altersversorgung und Contractual Trust Arrangements in Deutschland ein. Zur Abbildung der Verpflichtungsseite und der Mitarbeiterstruktur des Unternehmens wird unter Einbezug aktuarischer Ansätze ein Mitarbeitermodell entwickelt. Das in der Arbeit entwickelte Portfoliomodell integriert die Verpflichtungs- und Vermögensseite und zeigt, wie das Vermögen zur Deckung leistungsorientierter Zusagen zur betrieblichen Altersversorgung unter Einbezug der Unternehmensperspektive mit Hilfe dynamischer Risikonebenbedingungen geeignet angelegt werden kann.
14

Anlagestrategien für Pensionsvermögen im Rahmen von Contractual Trust Arrangements

van den Bergh-Mehner, Stefanie 04 January 2012 (has links)
Die vorliegende Arbeit behandelt die Anlage von Pensionsvermögen im Rahmen von Contractual Trust Arrangements. Es wird untersucht, welche Anlagestrategien sich unter Berücksichtigung bilanzieller, verpflichtungs- und vermögensseitiger Rahmenbedingungen zur Anlage von Pensionsvermögen eignen. Anhand eines geeigneten Anlagemodells für Pensionsvermögen und der Durchführung einer stochastischen Simulation wird analysiert, welchen Einfluss unterschiedliche Anlagestrategien auf die Entwicklung des Pensionsvermögens haben. Die Arbeit geht zunächst auf den Hintergrund der betrieblichen Altersversorgung und Contractual Trust Arrangements in Deutschland ein. Zur Abbildung der Verpflichtungsseite und der Mitarbeiterstruktur des Unternehmens wird unter Einbezug aktuarischer Ansätze ein Mitarbeitermodell entwickelt. Das in der Arbeit entwickelte Portfoliomodell integriert die Verpflichtungs- und Vermögensseite und zeigt, wie das Vermögen zur Deckung leistungsorientierter Zusagen zur betrieblichen Altersversorgung unter Einbezug der Unternehmensperspektive mit Hilfe dynamischer Risikonebenbedingungen geeignet angelegt werden kann.
15

Coronary Artery Plaque Segmentation with CTA Images Based on Deep Learning / Segmentering baserad på djupinlärning i CTA-bilder av plack i kransartärer

Shuli, Zhang January 2022 (has links)
Atherosclerotic plaque is currently the leading cause of coronary artery disease (CAD). With the help of CT images, we can identify the size and type of plaque, which can help doctors make a correct diagnosis. To do this, we need to segment coronary plaques from CT images. However, plaque segmentation is still challenging because it takes a lot of energy and time of the radiologists. With the development of technology, some segmentation algorithms based on deep learning are applied in this field. These deep learning algorithms tend to be fully automated and have high segmentation accuracy, showing great potential. In this paper, we try to use deep learning method to segment plaques from 3D cardiac CT images. This work is implemented in two steps. The first part is to extract coronary artery from the CT image with the help of UNet. In the second part, a fully convolutional network is used to segment the plaques from the artery. In each part, the algorithm undergoes 5-fold cross validation. In the first part, we achieve a dice coefficient of 0.8954. In the second part, we achieve the AUC score of 0.9202 which is higher than auto-encoder method and is very close to state-of-the-art method. / Aterosklerotisk plack är för närvarande den främsta orsaken till kranskärlssjukdom (CAD). Med hjälp av CT-bilder kan vi identifiera storlek och typ av plack, vilket kan hjälpa läkare att ställa en korrekt diagnos. För att göra detta måste vi segmentera koronarplack från CT-bilder. Emellertid är placksegmentering fortfarande utmanande eftersom det tar mycket energi och tid av radiologerna. Med utvecklingen av teknik tillämpas vissa segmenteringsalgoritmer baserade på djupinlärning inom detta område. Dessa djupinlärningsalgoritmer tenderar att vara helt automatiserade och har hög segmenteringsnoggrannhet, vilket visar stor potential. I detta dokument försöker vi använda djupinlärningsmetoden för att segmentera plack från 3D-hjärt-CT-bilder. Detta arbete genomförs i två steg. Den första delen är att extrahera kranskärlen från CT-bilden med hjälp av UNet. I den andra delen används ett helt konvolutionerande nätverk för att segmentera placken från artären. I varje del genomgår algoritmen 5-faldig korsvalidering. I den första delen uppnår vi en tärningskoefficient på 0,8954. I den andra delen uppnår vi AUC-poängen 0,9202, vilket är högre än den automatiska kodarmetoden och är mycket nära den senaste metoden.
16

Searches for a Dark Matter annihilation signal with Imaging Atmospheric Telescopes

Birsin, Emrah 23 July 2015 (has links)
Erste Anzeichen für die Existenz von Dunkler Materie wurden 1933 entdeckt. Der Astrophysiker Fritz Zwicky beobachtete die Geschwindigkeitsverteilung im Coma Cluster und fand dabei heraus, dass 400 mal mehr Materie im Galaxie Haufen sein muss, damit dieser gravitativ gebunden sein kann oder der Galaxie Haufen würde sich aufösen. Trotz erheblicher Bemühungen über die letzten 80 Jahre ist nicht viel über Dunkle Materie bekannt. Das einzige was man weiÿ ist, dass Dunkle Materie gravitativ aber nicht elektromagnetisch wechselwirkt und Dunkle Materie stellt den gröÿten Bestandteil der Materie im Universum da. Doch derzeitige Experimente die nach Dunkler Materie suchen, sowohl direkte Suchen als auch indirekte, beginnen sensitiv genug zu werden um interessante Parameterbereiche von Dunkle Materie Kandidaten zu untersuchen wie das leichteste Super-symmetrische Teilchen, was bedeutet, dass die Entdeckung von Dunkler Materie in der nahen Zukunft sein könnte. In dieser Arbeit wird eine Signalsummierung von H.E.S.S. Zwerg Galaxien Daten durchgeführt und obere Ausschlussgrenzen berechnet. Weiterhin wird die Leistung einer Dunklen Materie Suche im galaktischen Zentrum durch CTA präsentiert für verschiedene mögliche Teleskop Anordnungen und verschiedene Annihilation Kanäle. Die Ergebnisse werden zeigen, dass CTA in der Lage sein wird geschwindigkeitsgemittelte Annihilations Wirkungsquerschnitte von 3 * 10^-26 cm^3s^1 und geringer, der geschwindigkeitsgemittelte Annihilations Wirkungsquerschnitt der für schwach wechselwirkende Dunkle Materie erwartet wird, in 100 h zu erreichen. Diese Beobachtungszeit kann innerhalb von ein bis zwei Jahren erreicht werden. / First indications for the existence of Dark Matter appeared in 1933. The astrophysicist Fritz Zwicky observed the velocity dispersion of the Coma Cluster and found out that 400 times the visible mass must be contained in the galaxy cluster or the cluster could not be gravitationally bound and would disperse.Despite extensive efforts over the last 80 years not much is known about Dark Matter. The facts known are that Dark Matter interacts via gravitation, does not interact electromagneticly and is the main constituent of matter. But current experiment searching for Dark Matter directly and indirectly begin to reach sensitivities that can probe interesting parameter spaces for Dark Matter candidates like the lightest supersymmetric particle, meaning the first Dark Matter detections could happen in the near future.In this thesis a dwarf stacking analysis for Dark Matter signal search using H.E.S.S. data is performed and a upper limit is calculated. Furthermore the prospect for a Dark Matter search with CTA in the galactic center region of the Milky Way is presented for different candidate arrays and different annihilation channels. The results will show that CTA will be able to reach velocity annihilation below 3 *10^-26 cm^3s^-1, the velocity annihilation crosssection expected for a weakly interacting Dark Matter particle, within 100 h of observation which can reasonably be acquired within one to two years.
17

Le centre Galactique aux très hautes énergies : modélisation de l’émission diffuse et premiers éléments d’analyse spectro-morphologique / The galactic center to vers high energies : diffuse emission modeling and first elements of spectromorphological analysis

Jouvin, Lea 27 September 2017 (has links)
Le centre Galactique (GC) est une région très riche et complexe. Le taux de supernovae (SN) associé à la formation d'étoiles massives y est très élevée et devrait créer une injection continue de rayons cosmiques (CRs) dans le GC à travers les chocs qu'elles produisent. Cette région abrite également un trou noir supermassif (SMBH) de $4 \times 10^6 \, \rm{M_{\odot}}$, nommé Sgr A*. De nombreux arguments ont permis de montrer que le SMBH pouvait accélérer des particules à très haute énergie (VHE); son activité actuelle et passée pourrait donc également contribuer à la population de CRs. En 2006, la collaboration H.E.S.S. a révélé la présence d'une émission diffuse à VHE dans les 100 pc centraux de la Galaxie, très corrélée à la distribution de matière moléculaire répartie dans la zone moléculaire centrale (CMZ). Une partie importante de cette émission a donc très probablement une origine hadronique mais celle-ci reste toujours inconnue. Nous présentons une nouvelle analyse spectrale et morphologique détaillée de la région en utilisant 10 ans de prise de données de H.E.S.S. ainsi qu’une modélisation de l'émission $\gamma$ induite par les SNe. Nous étudions l'impact de la distribution temporelle et spatiale des SNe dans le CMZ sur la morphologie et le spectre de l'émission: nous construisons un model 3D d'injection de CRs à VHE et d'une propagation diffusive dans la région avec une distribution de gaz réaliste. La contribution des SNe ne peut pas être négligée. Nous montrons qu’un profil piqué de rayon $\gamma$ ainsi qu’un excès de CRs vers le GC peuvent être obtenus en utilisant une distribution spatiale réaliste de SNe prenant en compte les amas d'étoiles massives centraux. La morphologie de l'émission est très dépendante de l'énergie dans ce scénario. Le profil de densité de CRs peut également être reproduit avec une injection stationnaire unique au centre par Sgr A* mais cela implique alors une morphologie stable en énergie. L'utilisation d'une analyse 3D est donc nécessaire pour distinguer les modèles. Nous présentons les premiers résultats de cette analyse que nous avons développé dans la librairie Gammapy afin d'ajuster simultanément un spectre et une morphologie sur des données. Avec la prochaine génération d'instruments comme le Cherenkov Telescope Array, les observations de régions avec une morphologie complexe, avec une émission diffuse ou de multiples sources, vont devenir de plus en plus nombreuses. Elles nécessitent donc également le développement de cette technique. Nous détaillons les premières validations de cette méthode appliquée sur des sources ponctuelles avec un outil Monte Carlo. Pour l’émission diffuse, nous présentons le nouveau spectre obtenu en utilisant une méthode que nous avons développée pour l’extraction spectrale 1D classique. Nous réalisons par ailleurs une analyse morphologique dans différentes bandes en énergie indépendantes en utilisant de nouveaux modèles spatiaux. Pour l'instant, aucune variation significative n'est détectée mais des observations supplémentaires sont nécessaires ainsi qu'une vraie analyse 3D de la région du GC pour pouvoir donner une conclusion définitive. Les observations de CTA permettront de donner des réponses précises à ces questions. / The Galactic center (GC) is a very rich and complex astrophysical region. The high supernovae (SN) rate associated with the strong massive star formation should create a sustained cosmic rays (CR) injection in the GC via the shocks they produce. This region also harbors a Super-Massive Black Hole (SMBH) of $4 \times 10^6 \, \rm{M_{\odot}}$, named Sgr A*. Since it has been argued that the SMBH might also accelerate particles up to very high energies (VHE), its current and past activity could contribute to the CR population. In 2006, the H.E.S.S. collaboration revealed the presence of a VHE diffuse emission in the inner 100 pc of the Galaxy in close correlation with the molecular matter spread in the central molecular zone (CMZ). A major part of this emission is thus certainly of hadronic origin but it still remains mysterious. We report a new detailed spectral and morphological analysis of this region using 10 years of H.E.S.S. observations as well as a detailed modelling of the $\gamma$-ray emission induced by the SNe. We study the impact of the spatial and temporal distribution of SNe in the CMZ on the VHE emission morphology and spectrum: we built a 3D model of VHE CR injection and diffusive propagation with a realistic gas distribution. The contribution of SNe can not be neglected. We show that a peaked $\gamma$-ray profile and CR excess towards the GC, can be obtained using realistic SN spatial distribution taking into account the central massive star clusters. A strong dependence on the morphology of the emission with the energy is expected in this scenario. The CR density profile can also be reproduced by a unique stationary injection at the center by Sgr A* but it implies a stable morphology across the energy range. To distinguish the models, we need a 3D analysis. We present the first results of this analysis that we started to design in the software Gammapy to simultaneously fit a spectral and morphological model to the data. The observations of complex morphological regions with diffuse emission or multiple sources will become more and more numerous with the next generation instruments such as the Cherenkov Telescope Array. They will also require the development of this technique. We detail the first validations of this method on point sources using a Monte Carlo tool. For the ridge emission, we report the new spectrum using a method that we developed for the classical spectral fitting necessary for faint emission. By using new spatial templates to describe the complexity of the diffuse emission, we perform a morphological analysis in different energy bands independently. No significant variation is found but more observations are needed to give a conclusive statement as well as a real 3D analysis in the GC region. The observations of CTA will allow to give precise answers to these questions.
18

Avaliação do catalisador CTA-MCM-41, modificado por poliacrilatos, na transesterificação de monoéster

Cruz, Fernanda Tátia 24 March 2014 (has links)
Made available in DSpace on 2016-06-02T19:55:39Z (GMT). No. of bitstreams: 1 5785.pdf: 4761732 bytes, checksum: 604d605ce379585335d48545e6063093 (MD5) Previous issue date: 2014-03-24 / Financiadora de Estudos e Projetos / The silica hybrid CTA-MCM-41 (where CTA is the cetyltrimethylammonium cation) was synthesized and used in the transesterification of ethyl acetate with methanol. This is a model reaction used to test basic catalysts for the production of biodiesel from vegetable oils and fats. The basic sites in the catalyst consist of siloxy anions associated with CTA cations. In earlier work, it was found that progressive deactivation of the catalyst occurred when it was reused, due to leaching of the CTA cations located within the pores and on the external surface, resulting in partial loss of the basicity required for this type of reaction. The challenge of the present work was to stabilize the catalytic activity of CTA-MCM-41 by restricting the loss of cations from its interior (since the basicity derives from the interaction between the CTA cation and the siloxy anion). To this end, novel modifications were made to the synthesis of CTA-MCM-41, involving the encapsulation of acrylate monomers in the hydrophobic interior of the micelles followed by their subsequent polymerization using the application of ultraviolet irradiation together with a photoinitiator. The polymers formed then interacted with the hydrophobic tails of the micelles, which restricted the exit of CTA from the interior of the pores, hence improving the stability of the catalyst. The combination of the traditional synthesis method with polymerization using a microemulsion is innovative, because there are no reports in the literature that describe a synthesis in which the initial step is performed using emulsified polymers. The emulsions and the synthesized solids were evaluated using small angle X-ray scattering (SAXS). The materials were also analyzed by Xray diffraction, elemental (CHN) analysis, infrared absorption spectroscopy, scanning electron microscopy, and thermogravimetry. All these techniques helped to identify the presence of the monomer, as well as the polymer, in the channels of the CTA-MCM-41. It was confirmed that the presence of the polymer increased the catalytic stability of these new silica hybrids applied in the transesterification reaction. / A sílica híbrida CTA-MCM-41 (onde CTA é o cátion cetiltrimetilamônio) foi empregada, tal como sintetizada, na transesterificação do acetato de etila com metanol. Esta é uma reação modelo para testar catalisadores básicos para a produção de biodiesel a partir de óleos vegetais e gorduras. Os sítios básicos desse catalisador são identificados como sendo os ânions silóxi (≡SiO-) associados aos cátions CTA. Em trabalhos anteriores foi verificado que ocorre a desativação catalítica em seus sucessivos usos, ocasionados pela lixiviação dos cátions CTA localizados no interior dos poros e também na sua superfície externa. Desta forma, tem-se a perda de parte da basicidade requerida pela formação de grupos silanóis (SiOH) para este tipo de reação. Este trabalho teve como objetivo o desafio de estabilizar cataliticamente a CTA-MCM-41 dificultando a saída dos cátions do seu interior, pois, como já mencionado, a basicidade é promovida pela interação do cátion CTA com o ânion silóxi. Para isso, foram realizadas modificações inéditas na síntese da CTA-MCM-41 como o encapsulamento de monômeros acrílicos (metila, butila, octila e dodecila) no interior hidrofóbico das micelas e sua posterior polimerização sob a ação da radiação ultravioleta e de um fotoiniciador. Desse modo, os polímeros formados interagiram com as caudas hidrofóbicas das micelas, dificultando a saída do CTA do interior dos poros, por conseguinte proporcionando uma melhora na estabilidade catalítica. O método tradicional de síntese realizado juntamente com a polimerização em emulsão é inovador, pois ainda não há relatos na literatura cuja etapa inicial da síntese seja por meio de polímeros emulsificados. Assim, as emulsões e os sólidos sintetizados foram avaliados por meio da técnica de espalhamento de raios X a ângulos pequenos (SAXS). Os materiais foram analisados pelas técnicas de difratometria de raios X, análise química elementar (CHN), espectroscopia de absorção na região do infravermelho, microscopia eletrônica de varredura (MEV) e termogravimetria. Todas as técnicas auxiliaram para comprovar a presença do monômero e também do polímero nos canais da CTA-MCM-41. Desse modo, verificou-se que a presença do polímero melhorou a estabilidade catalítica destas novas sílicas híbridas sintetizadas e aplicadas na transesterificação.
19

Exceptional outburst of the blazar CTA 102 in 2012: the GASP–WEBT campaign and its extension

Larionov, V. M., Villata, M., Raiteri, C. M., Jorstad, S. G., Marscher, A. P., Agudo, I., Smith, P. S., Acosta-Pulido, J. A., ˙arévalo, M. J., Arkharov, A. A., Bachev, R., Blinov, D. A., Borisov, G., Borman, G. A., Bozhilov, V., Bueno, A., Carnerero, M. I., Carosati, D., Casadio, C., Chen, W. P., Clemens, D. P., Di Paola, A., Ehgamberdiev, Sh. A., Gómez, J. L., González-Morales, P. A., Griñón-Marín, A., Grishina, T. S., Hagen-Thorn, V. A., Ibryamov, S., Itoh, R., Joshi, M., Kopatskaya, E. N., Koptelova, E., Lázaro, C., Larionova, E. G., Larionova, L. V., Manilla-Robles, A., Metodieva, Y., Milanova, Yu. V., Mirzaqulov, D. O., Molina, S. N., Morozova, D. A., Nazarov, S. V., Ovcharov, E., Peneva, S., Ros, J. A., Sadun, A. C., Savchenko, S. S., Semkov, E., Sergeev, S. G., Strigachev, A., Troitskaya, Yu. V., Troitsky, I. S. 21 September 2016 (has links)
After several years of quiescence, the blazar CTA 102 underwent an exceptional outburst in 2012 September-October. The flare was tracked from gamma-ray to near-infrared (NIR) frequencies, including Fermi and Swift data as well as photometric and polarimetric data from several observatories. An intensive Glast-Agile support programme of the Whole Earth Blazar Telescope (GASP-WEBT) collaboration campaign in optical and NIR bands, with an addition of previously unpublished archival data and extension through fall 2015, allows comparison of this outburst with the previous activity period of this blazar in 2004-2005. We find remarkable similarity between the optical and gamma-ray behaviour of CTA 102 during the outburst, with a time lag between the two light curves of approximate to 1 h, indicative of cospatiality of the optical and gamma-ray emission regions. The relation between the gamma-ray and optical fluxes is consistent with the synchrotron self-Compton (SSC) mechanism, with a quadratic dependence of the SSC gamma -ray flux on the synchrotron optical flux evident in the post-outburst stage. However, the gamma -ray/optical relationship is linear during the outburst; we attribute this to changes in the Doppler factor. A strong harder-when-brighter spectral dependence is seen both the in gamma-ray and optical non-thermal emission. This hardening can be explained by convexity of the UV-NIR spectrum that moves to higher frequencies owing to an increased Doppler shift as the viewing angle decreases during the outburst stage. The overall pattern of Stokes parameter variations agrees with a model of a radiating blob or shock wave that moves along a helical path down the jet.
20

Developing a measurement system of fluid velocities in rotating bed reactors

Sterner Boström, Måns January 2016 (has links)
SpinChem AB's rotating bed reactor (RBR) is a small cylindrical centrifuge that allowsfor eective convective reactions between chemical substances. The aim of my master'sdissertation was to develop a measurement system that could estimate the uid velocity insidethe RBR. This report covers a quick pre-study of dierent uid measurement methods,details how we designed and constructed the system using integrated circuits and other electroniccomponents, and illustrates calibration results and nal velocity measurements. Thesystem design was based on the architecture of hot-wire constant temperature anemometry(CTA), a technique that measures the uid velocity over a heated metal wire. The resultsof this project is the measurement system itself, and the calibration and velocity measurementsgathered from experimentation. Two issues we encountered was that the calibrationprocess resulted in an overestimation of the velocity in the order of 4000 cm/s, and thatthe response to changes in velocity rates was quite slow. However, a slight tuning of thetwo calibration constants A0 & B0 smoothed the velocity estimation out to 40 cm/s, whichis more what we would expect. This illustrated how sensitive the results were to errors inthe calibration. Further investigation of the slow response, and a more stringently executedcalibration setup, could make the CTA a potential candidate for estimating the uid velocityinside the RBR.

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