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No description available.

The intent of this study was two-fold. The first purpose was to apply Van Manen's model to specific strategies (i.e., written assignments) and supervisory practices (i.e., interviews) to examine levels of reflectivity demonstrated and if there were any changes in the reflectivity of student teachers throughout a student teaching period. The second purpose was to assess the applicability of Van Manen's model to a preservice physical education setting. Five physical education majors enrolled in a student teaching experience volunteered to participate. Five weekly web-based written assignments were selected and analyzed using Van Manen's model of reflection. In addition, two interviews were audiotaped, transcribed, and subjected to thematic analysis techniques. Using Naturalistic Inquiry as a method of analysis suggests that utilizing supervisory approaches, written assignments, and reflective teaching can foster important changes in reflectivity levels which encourage reflective thinking in physical education student teachers. Increased levels of sophistication among the participants as the semester progressed were noted and may be attributed to a developmental effect similar to Fuller's Concerns Theory. The results also support Pultorak's (1993) assertion that students can increase reflective thinking when fostered and encouraged in preservice programs. This study combines available resources (i.e., technology, supervisors) with Van Manen's model to assess reflectivity levels in a physical education setting. Findings indicate that Van Manen's model can be used objectively in a physical education setting and can be utilized in applying a quantitative measure to qualitative responses.

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Ten years (1997 - 2006) of summer (June, July, August) daytime (14 - 00 Z) Weather Surveillance Radar - 1988 Doppler data for Houston, TX were examined to determine the best radar-derived lightning forecasting predictors. Convective cells were tracked using a modified version of the Storm Cell Identification and Tracking (SCIT) algorithm and then correlated to cloud-to-ground lightning data from the National Lightning Detection Network (NLDN). Combinations of three radar reflectivity values (30, 35, and 40 dBZ) at four isothermal levels (-10, -15, -20, and updraft -10 degrees C) and a new radar-derived product, vertically integrated ice (VII), were used to optimize a radar-based lightning forecast algorithm. Forecasts were also delineated by range and the number of times a cell was identified and tracked by the modified SCIT algorithm. This study objectively analyzed 65,399 unique cells, and 1,028,510 to find the best lightning forecast criteria. Results show that using 30 dBZ at the -20 degrees C isotherm on cells within 75 km of the radar that have been tracked for at least 2 consecutive scan produces the best forecasts with a critical success index (CSI) of 0.71. The best VII predictor was 0.734 kg m-2 on cells within 75 km of the radar that have been tracked for at least 2 consecutive scans producing a CSI of 0.68. Results of this study further suggest that combining the radar reflectivity and VII methods can result in a more accurate lightning forecast than either method alone.

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No description available.

La pollution maritime est l’un des principaux accidents qui affectent l’environnement maritime pendant une longue période. Il est essentiel que les systèmes de détection et de surveillance des déversements d'hydrocarbures interviennent rapidement pour contenir le danger. Ces systèmes utilisent plusieurs techniques et capteurs, les plus récents étant ceux réalisés à distance à l'aide de systèmes satellitaires et aéroportés. L'Agence européenne pour la sécurité maritime (EMSA) a lancé en 2016 la nécessité d'utiliser un système complémentaire, utilisant des drones, aux systèmes de surveillance maritime actuels.Dans nos travaux, nous proposons l’utilisation des drones comme système de détection des déversements d’hydrocarbures. Le radar basé sur un drone permettra une évaluation rapide et le traitement des données en temps réel de la zone où le drapeau de possibles déversements est levé par des témoins. L' échographie en parallèle peut être utilisée pour couvrir une grande surface dans un moment critique. De plus, l' échographie à l'aide de drones offre une résolution spatiale élevée par rapport à un satellite et présente l'avantage principal d'un coût relativement réduit par rapport aux systèmes de détection aéroportés spécialisés. Les drones peuvent être désignés comme systèmes nadir (émission et réception à angle nul par rapport à la normale). Étant largement indépendants de la rugosité de surface, les rendements des systèmes nadir (ou quasi-nadir) bénéficieront de la prédominance de la diffusion spéculaire et permettront une détection même par vent très faible. Les mêmes conditions sont considérées comme inappropriées pour la détection à l'aide d'autres techniques récentes.Dans cette thèse, nous présentons une nouvelle approche probabiliste qui utilise un radar à large bande d'aspect nadir pour les applications de détection de la pollution maritime. L’approche proposée combine un modèle de diffusion monocouche et des statistiques bayésiennes afin d’évaluer la probabilité de détection de marées noires, dans une plage plausible d’épaisseurs, sur l’eau de mer. Nous présentons un cadre d’algorithmes qui utilise des mesures de la valeur de réflectivité pour détecter les déversements de pétrole. L'infrastructure prend en charge une ou plusieurs mesures collectées à une ou plusieurs fréquences dans les bandes C et X. L'analyse des performances des trois types de détecteurs (simple, double et tri-fréquence) est effectuée. L'analyse des résultats obtenus à partir des interfaces de surfaces planes et rugueuses est également présentée.Nous complétons les algorithmes de détection par une nouvelle approche visant à estimer l’épaisseur de la nappe de pétrole. Nous présentons des estimateurs à probabilité unique, double et multifréquences maximum. Ces derniers utilisent l'algorithme de distance minimum euclidienne, dans des ensembles de constellation prédéfinis 1-D, 2-D ou K-D, sur des réflectivités simulées pour estimer l'épaisseur de la marée noire. Les algorithmes dérivés sont présentés et testés à l'aide d'une simulation de Monte-Carlo.Pour pouvoir passer aux prototypes et aux applications réelles, les résultats nécessitent une validation expérimentale. Par conséquent, nous présentons également une méthode rapide et efficace pour l'extraction à distance des coefficients de réflexion de puissance sur une structure multicouche modélisant un déversement d'hydrocarbures à la surface de l'eau de mer. Les résultats expérimentaux obtenus sont analysés et comparés à des calculs théoriques. / Oil spill in sea water is one of the main accidents that adversely affect the maritime environment for a long period of time. It is crucial to have oil spill detecting and monitoring systems to have quick intervention to contain the danger. Such systems use several techniques and sensors, where most recent ones are those done remotely using satellite and airborne systems. The European Maritime Safety Agency (EMSA) launched in 2016 the need to use a complementary system, using drones, to the present satellite maritime surveillance systems.In our work, we propose the use of the drones for oil spill detection system. The drone-based radar will allow quick assessment and real time data processing of the area where the flag of possible spills is raised by witnesses. Parallelization in scanning can be used to cover large area in a critical time. Furthermore, scanning with drones provides high spatial resolution compared to satellite and with a principal advantage of relative low cost compared to dedicated airborne detection systems. Drones can be designated as nadir-looking systems (transmit and receive at zero angle from the normal). Being largely independent of surface roughness, the returns from nadir (or near-nadir) systems will benefit from the dominance of the specular scattering and allow detection even in very low wind conditions. The same conditions are considered to be unsuitable for detection using other recent techniques.In this thesis, we present a new probabilistic approach which uses nadir-looking wide-band radar for oil spill detection applications. The proposed approach combines a single layer scattering model with Bayesian statistics in order to evaluate the probability of detection of oil slicks, within a plausible range of thicknesses, on seawater. We present a framework of algorithms that utilize measurements of the reflectivity value to detect oil spills. The framework supports one or more measurements collected at single or multiple frequencies in the C-band and X-band. Performance analysis of all three types of detectors (single, dual- and tri-frequency) is done. The analysis for the results obtained from both flat- and rough- surfaces interface is also presented.We complement the detection-algorithms by a new approach targeting the estimation of the oil slick thickness. We present Maximum Likelihood single-, dual- and multi-frequency estimators. The latter use Minimum-Euclidean distance algorithm, in pre-defined 1-D, 2-D or K-D constellation sets, on simulated reflectivities to estimate the thickness of the oil slick. The derived algorithms are presented and tested using Monte-Carlo simulation.To be able to move forward to prototypes and real applications, the results need experimental validation. Therefore, we also present a fast and efficient method for the remote extraction of the power reflection coefficients on multilayer structure modeling an oil spill on the top surface of sea water. Experimental results obtained are analyzed and compared to theoretical calculations.

Heeding Hillard’s call for teachers to crack the walls of the matrix (inequitable schooling), this qualitative case study used Bronfenbrenner’s ecological systems theory as a theoretical lens and methodological tool to investigate the reflections of three elementary pre-service teachers. The first research question examined participants’ reflections as they were learning about teaching culturally and linguistically diverse students. The second question explored how these reflections connected to their developing culturally relevant beliefs and practices. To investigate these research questions the data sources collected for each participant included a pre/post Love & Kruger questionnaire, three individual semi-structured interview transcripts, eight written course documents, and two individual member written records. Cross case and within case analyses were conducted using a priori and open coding for all data and utilized the analytic strategy of relying on theoretical propositions. The theoretical proposition for this study was that teachers who reflected across systems of influences had more culturally relevant beliefs and practices. Findings from the cross case analysis suggested that (a) participants’ had shared patterns of reflectivity (b) drew upon multiple tools of references when confronted with less culturally relevant teaching in the field and program and (c) some course assignments facilitated participants’ reflection across systems more than others. The results from the within case analysis suggested that (a) participants’ racial identity experiences were the lenses they used to reflect on what being a culturally relevant teacher meant (b) some participants experienced cultural dissonance in the teacher development program as they considered culturally relevant pedagogy and (c) critical reflections across systems of influence revealed more developed understandings of culturally relevant pedagogy. This study offers insights about using critical reflectivity in developing pre-service teachers’ understandings of culturally relevant pedagogy.

The temperature dependence of the band structure of ZnO has been studied on epitaxial films and bulk crystals with the methods of temperature dependent photoluminescence, photoconductivity, reflectivity and transmission spectroscopy. A major question investigated was the intriguing detail that could be resolved in band edge photoconductivity spectra of both high quality ZnO bulk crystals as well as epitaxial films. The connection of these spectral details in photoconductivity to the excitonic band structure of ZnO was made by comparison to the other spectroscopic methods which have a better understood relation to the semiconductor band structure. Photoluminescence spectroscopy enabled us to get a direct and reliable feedback about the energy fine structure of emitting levels in ZnO. Comparison of the emitting levels of epitaxial films with the emitting levels of high quality bulk material allowed the identification of dominating defect structures and impurities in the epitaxial films. The investigation of the effect of annealing on these emission lines finally allowed us to get a better understanding of the effects of annealing on the crystal and electric structure of epitaxially grown heterostructural films and allowed the determination of the optimum temperature range to be used for improved crystal quality. It has been investigated if temperature dependent reflectivity can serve as a simple tool for the examination of the temperature dependence of the band structure of ZnO. The appeal of reflectivity is its enhanced sensitivity only to free excitonic transitions. This proved a valuable simplification compared to the methods of photoluminescence and photoconductivity: Photoluminescence is limited by phonon-broadening of the multitude of emission levels in the band gap region of ZnO, and photoconductivity has a multitude of processes that are potentially contributing to its spectra, making the identification of their relation to the band structure less reliable. Therefore the applicability of reflectivity for the deduction of the temperature dependence of the band structure has been investigated, by measuring the temperature dependence of the energy positions of the characteristic reflectivity features, with particular focus on the effect of phonon broadening and interaction of close lying resonator levels. The investigation of the temperature dependence of photoconductive centres was enabled through the resulting possibility of directly relating the purely excitonic reflectivity spectra to the complex features in photoconductivity. The temperature dependent evolution of the spectra obtained by photoconductivity then revealed that there are at least two types of photoconductive processes that have to be distinguished: features in photoconductivity that are directly related to the band structure proved to be distinguishable from slow defect related processes in terms of their response speed. For the samples of bulk ZnO as well as epitaxial films, the peaks in photoconductivity only had a meaningful position in regard to the band structure for the cases of spectra that are dominated by fast processes. The spectra dominated by slow processes showed a meaningful temperature dependence of respective dips in the spectra. The strong response of fast photoconductive levels in bulk ZnO allowed us to directly observe the A- and B-free excitons by photoconductivity. Additional fine structure could be observed that is likely to be related to the narrow photo emission lines of neutral as well as ionized donor bound excitons and the upper polariton branch of the A-free exciton. These findings agree with the temperature dependence of related Anti-Stokes phonon replica levels that allow a first estimate of the activation energies of the zero-phonon lines. The energy and temperature dependent lateral transport properties of ZnO are expected to be of importance in ZnO device technology