In this dissertation, methods are designed and validated for the utilization of hyperspectral hypertemporal remotely sensed data in target detection applications. Two new classes of methods are designed to optimize the selection of target detection features from spectro-temporal space data. The first method is based on the consideration that all the elements of the spectro-temporal map are independent of each other. The second method is based on the consideration that the elements of the spectro-temporal map have some vicinal dependency among them. Methods designed for these two approaches include various stepwise selection methods, windowing approaches, and clustering techniques. These techniques are compared to more traditional feature extraction methods such as Normalized Difference Vegetation Index (NDVI), spectral analysis, and Principal Component Analysis (PCA). The efficacies of the new methods are demonstrated within an aquatic invasive species detection application, namely discriminating waterhyacinth from other aquatic vegetation such as American lotus. These two aquatic plant species are chosen for testing the proposed methods as they have very similar physical characteristics and they represent a practical life target detection problem. It is observed from the overall classification accuracy estimates that the proposed feature extraction methods show a marked improvement over conventional methods. Along with improving the accuracy estimates, these methods demonstrate a capability to drastically reduce the dimensionality while retaining the desired hyperspectral hypertemporal features. Furthermore, the feature set extracted using the newly developed methods provide information about the optimum subset of the hyperspectral hypertemporal data for a specific target detection application, which makes these methods serve as tools to strategize more intelligent data collection plans.

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No description available.

Single-atom and cluster catalysts have been receiving significant interest due to not only their capability to approach the limit of atom efficiency but also to explore fundamentally unique properties. Supported Pt-group single atoms and clusters catalysts in the subnanometer size regime maximize the metal utilization and were reported to have extraordinary activities and/or selectivities compared with nanoparticles for various reactions including hydrogenation reactions. However, the relationship between metal nuclearity, electronic and their unique catalytic properties are still unclear. Thus, it is crucial to establish their relations for better future catalyst design. Ethylene hydrogenation and acetylene hydrogenation are two important probe reactions with the simplest alkene and alkyne, and they have been broadly studied as the benchmark reactions on the various catalyst systems. However, the catalytic properties and reaction mechanism of those hydrogenation reactions for metal nuclearitiy in the subnanometer regime is still not well understood. In this study, we applied different characterization techniques including x-ray absorption fine structure (XAFS), X-ray diffraction (XRD), X-ray photoelectron spectroscopy(XPS), diffuse reflectance infrared spectroscopy (DRIFTS), calorimetry and high-resolution scanning transmission electron microscopy (STEM) to investigate the structure of Pt/TiO2 and Pd/COF single-atom catalysts and tested their catalytic properties for hydrogenation reactions. In order to develop such relations, we varied the nuclearity of Pt supported on TiO2 from single atoms to subnanometer clusters to larger nanoparticles. For acetylene hydrogenation, Pt in the subnanometer size regime exhibits remarkably high selectivity to ethylene compared to its nanoparticle counterparts. The high selectivity is resulted from the decreased electron density on Pt and destabilization of C2H4, which were rationalized by X-ray photoelectron spectroscopy and calorimetry results. On the other hand, the activity of H2 activation and acetylene hydrogenation decreased as Pt nuclearity decreased. Therefore, our results show there's a trade-off between activity and selectivity for acetylene hydrogenation. Additionally, the kinetics measurements of ethylene hydrogenation and acetylene hydrogenation were performed on Pt/TiO2 catalysts, and they found to be structure sensitive for both reactions, which the reaction orders and activation energy changes as particles size change. The activity of ethylene hydrogenation decreases, and activation energy increase from 43 to 86 kJ/mol, as Pt nuclearity decreased from an average size of 2.1 nm to 0.7 nm and single atoms. The reaction orders in hydrocarbons (ethylene and acetylene) were less negative on subnanometer clusters and single atoms in contract to nanoparticles. The results imply that hydrocarbons, ethylene and acetylene species, do not poison the catalyst on Pt in the subnanometer size regime, and hydrogen activation turn to competitive adsorption path with surface hydrocarbons species. Moreover, single atom Pd supported on imine-linked covalent organic framework was synthesized, characterized by a various of techniques including X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XAS), and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) of adsorbed CO, and evaluated its catalytic properties for ethylene hydrogenation. The XAS results show that Pd atoms are isolated and stabilized by two covalent Pd–N and Pd-Cl bonds. DRIFTS of CO adsorption shows a sharp symmetrical peak at 2130 cm−1. The Pd single atoms are active for hydrogenation of ethylene to ethane at room temperature. The reaction orders in C2H4 and H2 were 0.0 and 0.5 suggesting that ethylene adsorption is not limiting while hydrogen forms on Pd through dissociative adsorption. / Doctor of Philosophy / More than 90% of chemicals come from petroleum and natural gas, and most of these chemicals are composed of alkene and alkyne, hydrocarbons containing at least one double bonds or triple bonds, such as ethylene, propylene, butenes, butadiene. These small hydrocarbon molecules with carbon-carbon bonds (double or triple) are in great interest of fundamental study and serve as probe units for understanding more complex reactions. Catalysts are materials that can be added to a chemical reaction to accelerate the specific rate of reactions. Most catalysts are supported noble metals thus increase the utilization of metal atoms are important. Decreasing the particle size to increase the metal dispersion is the simple approach to maximize the atom efficiency. However, it is not well understood how do the electronic property and catalytic performance change as particle size decrease. In this work, we focus on the structure sensitivity on catalysts in sub-nanometer region. Supported Pt and Pd catalysts, known to be highly active for hydrogenation reactions, are studied on hydrogenation reactions of acetylene and ethylene, the simplest alkene and alkyne. The Pd and Pt catalysts with particle sizes ranging from single atoms, sub-nanometer clusters and nanoparticles were prepared, characterized and tested for hydrogenation reactions mentioned above. The results show that significantly change in electronic property, catalytic performance (activity and/or selectivity) and reaction kinetics of the catalysts as the particle size changing from nanometer to sub-nanometer region. The fundamental understanding of structure sensitivity on catalysts and their relations between surface structure, electronic property and catalytic performance presented in this work can help the researchers design better catalysts for future work.

Supported noble metal catalysts make the best utilization of noble metal atoms. Recent advances in nanotechnology have brought many attentions into the rational design of catalysts in the nanometer and subnanometer region. Recent studies showed that catalysts in the subnanometer regime could have extraordinary activity and selectivity. However, the structural performance relationships behind their unique catalytic performances are still unclear. To understand the effect of particle size and shape of noble metals, it is essential to understand the fundamental reaction mechanism. Single atoms catalysts and subnanometer clusters provide a unique opportunity for designing heterogeneous catalysts because of their unique geometric and electronic properties. CO oxidation is one of the important probe reactions. However, the reaction mechanism of noble single atoms is still unclear. Additionally, there is no agreement on whether the activity of supported single atoms is higher or lower than supported nanoparticles. In this study, we applied different operando techniques including x-ray absorption fine structure (XAFS), diffuse reflectance infrared spectroscopy (DRIFTS), with other characterization techniques including calorimetry and high-resolution scanning transmission electron microscopy (STEM) to investigate the active and stable structure of Ir/MgAl2O4 and Pt/CeO2 single-atom catalysts during CO oxidation. With all these characterization techniques, we also performed a kinetic study and first principle calculations to understand the reaction mechanism of single atoms for CO oxidation. For Ir single atoms catalysts, our results indicate that instead of poisoning by CO on Ir nanoparticles, Ir single atoms could adsorb more than one ligand, and the Ir(CO)(O) structure was identified as the most stable structure under reaction condition. Though one CO was strongly adsorbed during the entire reaction cycle, another CO could react with the surface adsorbed O* through an Eley-Rideal reaction mechanism. Ir single atoms also provide an interfacial site for the facile O2 activation between Ir and Al with a low barrier, and therefore O2 activation step is feasible even at room temperature. For Pt single-atom catalysts, our results showed that Pt(O)3(CO) structure is stable in O2 and N2 at 150 °C. However, when dosing CO at 150 °C, one surface O* in Pt(O)3(CO) could react with CO to form CO2, and the reacted O* can be refilled when flowing O2 again at 150 °C. This suggests that an adsorbed CO is present in the entire reaction cycle as a ligand, and another gas phase CO could react with surface O* to form CO2 during low-temperature CO oxidation. Supported single atoms synthesized with conventional methods usually consist of a mixture of single atoms and nanoparticles. It is important to quantify the surface site fraction of single atoms and nanoparticles when studying catalytic performances. Because of the unique reaction mechanism of Ir single atoms and Ir nanoparticles, we showed that kinetic measurements could be applied as a simple and direct method of quantifying surface site fractions. Our kinetic methods could also potentially be applied to quantifying other surface species when their kinetic behaviors are significantly different. We also benchmarked other in-situ and ex-situ methods of quantifying surface site fraction of single atoms and nanoparticles. To bridge the gap between single atoms and nanoparticles and have a better understanding of the effect of nuclearity on CO oxidation, we also studied supported Ir subnanometer clusters with the average size less than 0.7 nm (< 13 atoms) prepared by both inorganic precursor and organometallic complex Ir4(CO)12. Low-temperature CO adsorption indicates that CO and O2/O could co-adsorb on Ir subnanometer clusters, however on larger nanoparticle the particle surface is covered by CO only. Additional co-adsorption of CO and O2 was studied by CO and O2 calorimetry at room temperature. CO oxidation results showed that Ir subnanometer clusters are more active than Ir single atoms and Ir nanoparticles at all conditions, and this could be explained by the competitive adsorption of CO and O2 on subnanometer clusters. / Doctor of Philosophy / CO oxidation is one of the important reactions in catalytic converters. Three-way catalysts, typically supported noble metals, are very efficient at high temperature but could be poisoned by CO at cold start. Better designed catalysts are required to improve the performance of the catalytic converter to lower the emissions of gasoline engines. To reach this goal, more efficient use of the noble metal is required. Single-atom catalysts consist of isolated noble metal atoms supported on different supports, which provide the best utilization of noble metal atoms and provides a new opportunity for a better design of heterogeneous catalysts. The unique electronic and geometric properties of metal single atoms catalysts could lead to a better activity and selectivity. Subnanometer clusters have also been shown to have unique electronic properties. With a better understanding of the structure of supported single atoms and subnanometer clusters, their catalytic performance can be optimized for better catalysts in the catalytic converter and other applications. In this work, we applied in-situ and operando characterization, kinetic studies and first principle calculations aiming to understand the active and stable structure of noble metal single atoms and vi subnanometer clusters under reaction condition, and their reaction mechanisms during CO oxidations. For MgAl₂O₄ supported Ir single atoms, our results suggest that CO could be co-adsorbed with O₂/O under reaction conditions. These multiple ligands adsorption leads to a unique reaction mechanism during CO oxidation. Though one CO was adsorbed during the whole reaction cycle, another gas phase CO could react with the O* species co-adsorbed with CO through an Eley-Rideal mechanism. This suggests that Ir single atoms are no longer poisoned by CO, and on the other hand the O₂ can be activated on an interfacial site with a low reaction barrier. Ir subnanometer clusters showed higher activities than Ir single atoms and nanoparticles. In-situ IR and high energy resolution fluorescence detected – X-ray absorption near edge spectroscopy (HERFD-XANES) showed that CO could co-adsorb with O₂ at room temperature, and this competitive adsorption could explain the high activity during CO oxidation. Supported Ir single atoms and subnanometer clusters are not poisoned by CO and O₂ could be co-adsorbed, this could be potentially applied to solve the poisoning of catalyst in the catalytic converter at cold start temperature. We also performed kinetic study on CeO₂ supported Pt single atoms. Similar behavior was observed, and we showed that the CO and O co-adsorbed complex is stable in O₂ and N₂, but could react in CO. With the understanding of the active structure of noble metal single atoms and the origin of activities, better-designed catalysts can be synthesized to improve the activity and selectivity of low-temperature oxidation reactions.

De plus en plus d'importance est accordée à la création d'objets 3D en raison des récents essors technologiques. Il est donc crucial de fournir des outils appropriés et accessibles aux utilisateurs de tous les horizons. Malheureusement, les outils traditionnellement utilisés en création 3D sont conçus pour des professionnels, exigent des formations complexes et de longue durée, et ne sont pas adaptés à ceux inexperimentés qui forment la vaste majorité des utilisateurs potentiels. Nous proposons un outil de création simplifié qui utilise des méthodes inspirées d'esquisses. Dans un premier temps, le maillage désiré est créé à partir d'un contour tracé. L'intérieur est gonflé suivant la méthode de Dvoroznak et al. Dans un deuxième temps, la hauteur des sommets du maillage est manipulée en modifiant les courbes formées par l'ombrage. Cet ombrage provient d'un modèle de réflexion Lambertien pour une lumière directionnelle donnée. Notre méthode consiste à utiliser les courbes formées par la méthode des charactéristiques associée au problème de figure dérivée de l'ombre (Shape-From-Shading). Avec les courbes, nous identifions les régions affectées par la modification de l'ombrage. L'une de ces régions sera utilisée pour interpoler l'ombrage d'après la nouvelle isophote. À partir de ce nouvel ombrage, les courbes de la méthode des characteristiques seront utilisées afin de trouver le nouveau déplacement en s'assurant d'altérer uniquement la région affectée par le changement dans l'ombrage. Les maillages créés peuvent ensuite être combinés suivant la méthode proposée par Dvoroznak et al. afin de former un maillage unique et complexe. Notre outil se veut plus intuitif que les outils traditionnels de création. Nos résultats en illustrent le potentiel. / Due to recent technological advances, the creation of 3D objects is becoming more important. It is critical to offer appropriate and accessible tools to users from diverse backgrounds. Unfortunately, the tools traditionally used in 3D creation are designed for professionals, require complex and time-consuming training, and are unsuitable for inexperienced users who form the vast majority of potential users. We propose a simplified creation tool that uses sketch-based methods. First, the desired mesh is created from a traced outline. The interior is inflated following the method of Dvoroznak et al. Second, the height (displacement) of the mesh is achieved by altering the strips created by shading. Shading is the result of a Lambertian reflection model for a given directional light. Our method consists of using the strips from the method of characteristics applied to solve Shape-From-Shading. Using the strips, we identify the regions affected by the change in shading. One of these regions will be used to interpolate the shading according to the new isophote. From this new shading, the characteristic strips will be used to find the new height, ensuring that only the region affected by the change in shading is altered. The meshes created can then be combined, inspired by the method proposed by Dvoroznak et al. to form a single, complex mesh. Our tool is designed to be more intuitive than the ones provided by professional 3D software. Our results illustrate its potential.

V této práci je prezentována inovativní metoda zvaná \textit{Zobrazovací Reflektometrie}, která je založena na principu spektroskopické reflektometrie a je určena pro vyhodnocování optických vlastností tenkých vrstev .\ Spektrum odrazivosti je získáno z map intenzit zaznamenaných CCD kamerou. Každý záznam odpovídá předem nastavené vlnové délce a spektrum odrazivosti může být určeno ve zvoleném bodu nebo ve vybrané oblasti.\ Teoretický model odrazivosti se fituje na naměřená data pomocí Levenberg~-~Marquardtova algoritmu, jehož výsledky jsou optické vlastnosti vrstvy, jejich přesnost, a určení spolehlivosti dosažených výsledků pomocí analýzy citlivosti změn počátečních nastavení optimalizačního algoritmu.

Thesis (MScAgric (Viticulture and Oenology))--Stellenbosch University, 2008. / Soil is a component of the environment and sustains growth of several plants and animals. It forms part of the biosphere and can be described as the interface between the atmosphere and the lithosphere. The interaction between soil, climate and topography and the resulting agricultural aptitude forms the concept of terroir. This relationship is complex and it is difficult to quantify the contribution of each. Grapevines are exposed to an array of soil types. Soils have varying colours, which can be ascribed to their origin from different parent materials and pedogenetic factors. Historical and experimental evidence points to the key role that soil physical conditions play in determining grape berry composition, but other soil related factors may also play a role. This study was conducted to investigate the effect of soil surface colour on the vegetative and reproductive growth characteristics of Cabernet Sauvignon. The aim was to determine whether a relationship exists between soil colour, reflective light quality below and inside the grapevine canopy, vegetative growth of the grapevine and the berry and wine composition. The reflected light from soils was measured in three positions of the canopy and across the light spectrum (300–2500 nm) for three different soil surface treatments (black, red and grey). The effect of soil colour on vegetative parameters, yield and berry composition and wine quality was investigated. Soil surface colour resulted in differences in the reflected light quality below and in the canopy. The differences in the light quality were associated with differences in vegetative parameters such as mean main leaf, with grey soils inducing higher values. Potassium levels of the grapes and berry number per bunch appeared to be influenced by soil surface colour throughout berry development with red and black soils having higher levels of potassium and berry number per bunch than grey soils. Grape ripening parameters were not influenced by soil surface colour, but the grey treatment had a significantly more intense grape colour measured at 520 nm (red pigments). It is assumed that the importance of soil colour is its association with the physical and the pedogenetic properties that contribute to the grapevine water balance. From these results it can be concluded that soil surface colour appeared to have a direct effect on some aspects of vegetative and reproductive growth, and berry composition, but the contribution of different wavebands and mechanism of their effect deserves further study.

The aims of this work were 1) to assess whether sorghum (Sorghum bicolor (L.) Moench) genotypes originating from the India can be grown and analyzed in the climatic conditions of central Europe and 2) to find out the utilization potential of selected non- destructive and destructive methods based mostly on the chlorophyll a fluorescence measurements and the determination of photosynthetic pigments' content for the differentiation of sorghum genotypes based on their presumed drought tolerance. Field experiments made during 2 years compared 15 genotypes of this species (2 stay-green parental lines, 2 senescent parental lines and 11 introgression lines with stay-green loci), 2 of these genotypes were further analyzed in greenhouse conditions where the water deficit was induced by a cessation of watering for 12 days. The field-grown plants showed some differences between individual genotypes in all measured parameters; however, for the majority of the genotypes these differences were not statistically significant. The stay-green parental genotype B35 differred the most from the other ones in both field seasons, but the other stay-green genotypes usually did not differ from the senescent genotypes. No significant differences between both greenhouse-tested genotypes (presumably contrasting in their...

Approved for public release; distribution in unlimited. / Traditionally, digital imaging systems rely on the use of dedicated photodetectors to capture specific wavelengths in the visible spectrum. These photodetectors, which are commonly made of silicon, are arranged as arrays to capture the red, green and blue wavelengths. The signal captured by the individual photodetectors must then be interpolated and integrated to obtain the closest color match and the finest possible resolution with reference to the actual object. The use of spatially separated detectors to sense primary colors reduces the resolution by a factor of three compared to black and white imaging. The FOVEON detector technology greatly improves the color and resolution of the image through its vertically arranged, triple well photodetector. This is achieved by exploiting the variation of absorption coefficient of silicon with wavelength in the visible spectrum. Hence, in a silicon detector, the shorter wavelength (e.g. blue) would be mainly absorbed at a shallow depth. A longer wavelength (e.g. red) would penetrate the material deeper than the shorter wavelengths and be primarily absorbed at a greater depth. By producing a layered silicon detector, all three primary colour wavelengths of red, green and blue can be captured simultaneously. This thesis aims to study the FOVEON camera's ability to image light from the near Infrared (NIR) to the Ultra-Violet (UV) range of the electromagnetic spectrum. The imaged obtained using a set of bandpass filters show that the camera has response both in the UV as well as NIR regions. / Major, Singapore Armed Forces