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The Global ETD Search service is a free service for researchers
to find electronic theses and dissertations. This service is
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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.
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Showing 21 to 24 of 24 (0.038 seconds)Spelling suggestions: "subject:"tts"" "subject:"tots""
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Returning to Our Roots: An Anthropological Evaluation of the Farm to Keiki ProgramMigdol, Steven Jeffrey 12 1900 (has links)
Farm to school programs are becoming a popular intervention to address childhood obesity. The hope is to prevent later chronic illnesses such as diabetes and cardiovascular disease that can result from eating high-fat/high-calorie diets that are low in consumption of fresh fruits and vegetables. This study explores the impacts of one such program, Farm to Keiki, on students, their families, and teachers at two Native Hawaiian preschools on the island of Kauaʽi, Hawaiʽi. This program combined lessons about plants and nutrition with gardening at school and tastetesting in the classroom. Rooted in critical medical anthropology, this study utilized a combination of quantitative and qualitative methods to understand these impacts, as well as the historical and cultural contexts that have contributed to dietary changes among Native Hawaiians. Through in-depth interviews and focus groups, families and teachers described how the program encouraged the children to try new foods and eat more produce, and how the children demonstrated new knowledge about plants and healthy eating. Participants also spoke of ways in which their own knowledge and eating habits changed, and families reported carrying over many of the program's activities at home by gardening and preparing meals together. Additionally, participants offered valuable feedback on ways the program could be improved. This study, which appears to be the first of its kind to involve a Native Hawaiian farm-toschool program, demonstrates that an anthropological approach can provide critical depth and understanding of how programs like Farm to Keiki affect students and the people close to them.
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Stabilité et stabilisation en temps fini des systèmes dynamiques / Finite Stability and Stabilization of Dynamic SystemsBhiri, Bassem 05 July 2017 (has links)
Ce mémoire de thèse traite de la stabilité en temps fini et de la stabilisation en temps fini des systèmes dynamiques. En effet, il est souvent important de garantir que pendant le régime transitoire, les trajectoires d'état ne dépassent pas certaines limites prédéfinies afin d'éviter les saturations et l'excitation des non-linéarités du système. Un système dynamique est dit stable en temps fini FTS si, pour tout état initial appartenant à un ensemble borné prédéterminé, la trajectoire d'état reste comprise dans un autre ensemble borné prédéterminé pendant un temps fini et fixé. Lorsque le système est perturbé, on parle de bornitude en temps fini FTB. Premièrement, des nouvelles conditions suffisantes assurant la synthèse d'un correcteur FTB par retour de sortie dynamique des systèmes linéaires continus invariants perturbés ont été développées via une approche descripteur originale. Le résultat a été établi par une transformation de congruence particulière. Les conditions obtenues sont sous forme de LMIs. Deuxièmement, l'utilisation de la notion d'annulateur combinée avec le lemme de Finsler, permet d’obtenir des nouvelles conditions sous formes LMIs garantissant la stabilité et la stabilisation en temps fini des systèmes non linéaires quadratiques. Enfin, pour obtenir des conditions encore moins pessimistes dans un contexte de stabilité en temps fini, de nouveaux développements ont été proposés en utilisant des fonctions de Lyapunov polynomiales / This dissertation deals with the finite time stability and the finite time stabilization of dynamic systems. Indeed, it is often important to ensure that during the transient regime, the state trajectories do not exceed certain predefined limits in order to avoid saturations and excitations of the nonlinearities of the system. Hence the interest is to study the stability of the dynamic system in finite time. A dynamic system is said to be stable in finite time (FTS) if, for any initial state belonging to a predetermined bounded set, the state trajectory remains within another predetermined bounded set for a finite and fixed time. When the system is disturbed, it is called finite time boundedness (FTB). In this manuscript, the goal is to improve the results of finite time stability used in the literature. First, new sufficient conditions expressed in terms of LMIs for the synthesis of an FTB controller by dynamic output feedback have been developed via an original descriptor approach. An original method has been proposed which consists in using a particular congruence transformation. Second, new LMI conditions for the study of finite time stability and finite time stabilization have been proposed for disturbed and undisturbed nonlinear quadratic systems. Third, to obtain even less conservative conditions, new developments have been proposed using polynomial Lyapunov functions
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Robuste Lokalisierung von autonomen Fahrzeugen mittels LandmarkenGrünwedel, Sebastian 07 February 2008 (has links)
Die Fahrzeuglokalisierung ist im Bereich der Fahrerassistenzsysteme von entscheidender
Bedeutung und Voraussetzung fur verschiedene Anwendungen der Robotik, wie z.B.
Navigation oder Kollisionsvermeidung fur fahrerlose Transportsysteme (FTS).
In dieser Arbeit wird ein Verfahren zur Lokalisierung mittels Landmarken vorgestellt,
die eine Orientierung bezuglich einer Karte ermoglichen. Dabei werden der Erweiterte-
Kalman-Filter und der Partikel-Filter fur diese Aufgabe untersucht und verglichen. Ein
Schwerpunkt dieser Betrachtungen stellt dabei der Partikel-Filter dar. Die besondere
Problematik der Initialisierung wird ausfuhrlich fur beide Filter dargestellt.
Simulationen und Versuche zeigen, dass sich der Partikel-Filter fur eine robuste
Lokalisierung der Fahrzeugposition verwenden lasst. Im Vergleich dazu kann der
Erweiterte-Kalman-Filter nur im begrenzten Maße eingesetzt werden. / The localization of vehicles is of vital importance in the field of driver assistance
systems and a requirement of different applications for robotics, i.e. navigation or
collision avoidance for automatic guided vehicle systems.
In this thesis an approach for localization by means of landmarks is introduced,
which enables an orientation regarding a map. The extended Kalman filter and the
particle filter are analyzed and compared. The main focus for this consideration is on
the particle filter. The problematic for initialization is discussed in detail for both
filters.
Simulations and tests prove that the particle filter is suitable for robust localization
of the vehicle position. Compared to this, the extended Kalman filter can only be
used to a certain extend.
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Constructing and Commissioning HELIOS – A High Harmonic Generation Source for Pump-Probe Measurements with sub 50 fs Temporal Resolution : The Development of Experimental Equipment for Extreme Ultraviolet SpectroscopyTerschlüsen, Joachim A. January 2016 (has links)
This thesis presents HELIOS, an in-house laboratory for time-resolved pump-probe spectroscopy with extreme-ultraviolet (XUV) probe radiation. A wide span of pump wavelengths can be generated using commercial laser equipment while XUV probe radiation is generated via a high harmonic generation process in a noble gas delivering probe photons with energies between 20 eV and 72 eV. The XUV beam path features a time-preserving monochromator and was constructed and built in-house. HELIOS features an overall time resolution of about 50 fs when using 800 nm pump and 41 eV probe photons. An energy resolution of 110 meV at 41 eV photon energy can be achieved. HELIOS features two beamlines. One µ-focus beamline with an XUV focal size of about 20 µm can be used with experiments that require such a small XUV focal size as well as with different end stations. The other beamline features a semi-permanently mounted end station for angle-resolved photoelectron spectroscopy under ultra-high vacuum conditions. Experiments demonstrating the usability of HELIOS and the two beamlines are presented. A pump-probe measurement on graphene demonstrates the capability of determining a large part of the k-space in only one measurement due to the use of an ARTOF angle-resolved time-of-flight electron spectrometer. A non-angle-resolved pump-probe measurement on the conducting polymer PCPDTBT demonstrates the high signal-to-noise ratio achievable at this beamline in non-angle-resolved photoelectron-spectroscopy pump-probe measurements. The usability of the µ-focus beamline is demonstrated with time-resolved measurements on magnetic samples employing an in-house-designed spectrometer. These experiments allow the retrieval of element-specific information on the magnetization within a sample employing the transversal magneto-optical Kerr effect (T-MOKE). Additionally, a Fourier transform spectrometer for the XUV is presented, the concept was tested at a synchrotron and it was used to determine the longitudinal coherence of the XUV radiation at HELIOS.
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