Thèses : « Surface sciences »

1

Zhao, Jun. « Surface Raman spectroscopy : instrumentation and application in surface and corrosion sciences / ». The Ohio State University, 1997. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487948807588245.

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Nolin, Loïc. « Outils d'aide à l'étude des protéines : modélisation surfacique et visualisation sémantique des feuillets béta ». Reims, 2010. http://theses.univ-reims.fr/sciences/2010REIMS008.pdf.

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L'enjeu de ces travaux consiste en la représentation de motifs structuraux réguliers des protéines : les feuillets β. Les représentations classiques de la modélisation moléculaire n'étant pas satisfaisantes, étant donne qu'elles ne représentent pas les feuillets β dans leur ensemble, nous proposons nos modèles représentant ces structures sous forme de surfaces. Nous utilisons le logiciel open source ≪ BALLView ≫ pour créer nos propres modèles de feuillets β. La première approche utilise la description des feuillets β présente dans les fichiers issus de la ≪ Protein Data Bank ≫, la banque de données mondiale de structures protéiques, pour calculer une interpolation bidimensionnelle basée sur les splines de Catmull-Rom. La seconde approche utilise des carreaux de Bézier, construits a partir des résultats issus d'un algorithme d'attribution des structures secondaires des protéines, dont les feuillets β font partie. Ces approches sont les premières à représenter les feuillets β dans leur ensemble. Les modèles classiques ne représentent que les brins β. Pour visualiser leur orientation nous plaquons cette information par le biais de textures. Cela nous amène à considérer nos surfaces comme de nouveaux medias sur lesquels nous pouvons dépeindre des données supplémentaires par l'intermédiaire de méthodes de coloration (≪ Hydrophobic Cluster Analysis ≫, ≪ Molecular Hydrophobicity Potential ≫…). Nos modèles sont utilisables sur l'ensemble des fichiers au format PDB, en statique, mais également sur des fichiers de simulation de dynamique moléculaire. Nous pouvons alors constater l'évolution des feuillets β, leurs déformations, l'apparition de trous, d'invaginations ou de déchirures. Ces constatations nous amènent à baptiser nos modèles SheHeRASADe pour ≪ Sheets Helper for RepresentAtion of SurfAce Descriptors ≫. Nous nous intéressons, entre autres, à l'application de ces modèles sur les divers repliements protéiques des feuillets β repertoriés dans la classification CATH, ainsi qu'aux fibres amyloides, impliquées dans de nombreuses pathologies
The aim of this work consists in the representation of common structural motifs of proteins: the β sheets. The classical visualization modes are not satisfying, considering that they don't represent the whole β sheets. We propose innovative models materializing those structures using surfaces. We use the open source software "BALLView" to create our own β sheet models. The first one uses the β sheets description stored in files from the Protein Data Bank, the worldwide data bank of proteic structures, to compute a bidimensionnal interpolated surface based on Catmull-Rom splines. The second one uses Bezier patches defined from β sheets produced by a secondary structure prediction algorithm. Those models are the first ones to fully represent β sheets. Previous methods only represent β strands. In order to visualize their orientation, we map these important data to our surfaces by using textures. It leads us to consider our surfaces as a new medium on which we can depict additional information using coloring methods (Hydrophobic Cluster Analysis, Molecular Hydrophobicity Potential. . . ). Our models are available for any PDB formatted file, in both static and dynamic ways, using molecular dynamics simulations. We can observe the evolution of β sheets, deformations, holes appearances, invaginations or splits. Those observations lead us to call our models SheHeRASADe for "Sheets Helper for RepresentAtion of SurfAce Descriptors". We apply those models to the different proteic folds of β sheets listed in the CATH classification, and on amyloid fibrils involved in many diseases

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Thomas, Matthew Rhys. « Polyvinyl alcohol surface modification ». Thesis, University of Oxford, 2011. http://ora.ox.ac.uk/objects/uuid:279fe53b-7d61-43de-a91a-be658dd01eda.

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Poly(vinyl alcohol) (PVA) is a polymer used in numerous applications, principally those in which its high water solubility is a desirable asset. However there are also areas where PVA is limited by its inherent solubility (for example some specific environments in the biomedical field). This work has sought to overcome such limits by manipulating the surface of PVA in order to propose various means by which the surface solvent resistance might be increased while maintaining the bulk properties of the polymer. Both chemical and physical modifications have been tried and in each case progress has been made towards insolubilizing a single surface of the polymer when in film form. Grafting various species onto the surface of PVA was successfully performed. It is believed that such species bonded to the PVA via attachment to the hydroxyl groups (though this has not been proven conclusively). The data contained herein has led to the conclusion that the primary factor in reducing solubility this way is the removal of the hydroxyl groups, and not the attachment of specifically highly hydrophobic molecules. Introducing permanent cross-links into the surface region has been attempted via various routes. The data recorded shows promise however the system is far from optimised. The biggest challenge remaining is to optimise the depth of material cross-linked. Some steps have been made towards understanding and controlling this parameter though there is much scope for further investigation. The methods used have built on those used for bulk cross-linking and as such are new for the case of surface specific treatment. An interesting phenomenon in some semi-crystalline polymers reported in recent years is that of surface specific crystallization. This effect has been successfully induced and observed in PVA to produce what is believed to be a highly crystalline surface layer, and crystalline regions of PVA are generally accepted to be more water resistant than amorphous ones. In summary, in this work several surface-specific treatments for PVA have been trialled, providing options for post-film forming modification to reduce the surface water sensitivity whilst retaining the bulk properties of the polymer.

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Magnusson, Erik. « Implied Volatility Surface Construction ». Thesis, Umeå universitet, Institutionen för fysik, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-145894.

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Implied volatility surfaces are central tools used for pricing options. This thesis treats the topic of their construction. The main purpose is to uncover the most appropriate methodology for constructing implied volatility surfaces from discrete data and evaluate how well it performs. First some methods and techniques in use for such surface constructing are presented. Then the most attractive approach, chosen to contain 4 interesting models is studied. The models’ performances are tested on two price grids from the EURO STOXX 50 and Nikkei 225 indices. The found implied volatility surfaces give good and decent fits to the data, respectively. The surfaces are evaluated in terms of presence of static arbitrage and are found to have it, although mostly for strike price and time to maturity combinations which are somewhat abnormal and rarely traded. Arbitrage is found to be more prevalent in surfaces when the input data is of lower quality. The volatility surfaces’ shapes and absolute values are compared in between models but also within models for some of the best-fit producing parameter sets. The surfaces are found to differ in both cases for some strike and maturity combinations - sometimes with relative differences of more than 10%. This suggests that surfaces with good fits to the input data still can produce distinctly differing prices for some options. Calibrating the models with the chosen approach involves calculations with complex numbers in ways which potentially introduce problematic discontinuities due to branch crossings. This is investigated numerically as well as theoretically for the 4 models and found to be a significant problem in one of them. The three other models are found to avoid these problems under all valid parameter sets.

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Twetman, Theodor. « Multi View Image Stitching of Planar Surfaces on Mobile Devices : Large Surface Analog Notes Scanning ». Thesis, KTH, Robotik, perception och lärande, RPL, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-196554.

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Digital notes have numerous advantages compared to analog notes, yet the will to use pen and paper remains. Thus, a need to digitize handwritten notes arises. To make it as simple as possible a minimum amount of user interaction should be required. The aim of this project is to present a process of automated image capturing, followed by a process of automatic image stitching, given photos taken by a camera which is moved parallel to a whiteboard or similar planar scenery. The need stems from being able to obtain higher image quality than possible using only one overall picture. The processes is to be executed on mobile devices, with comparatively low computational capacity, within a reasonable time interval. A review and theoretical analysis is conducted of existing methods for all parts of the processes: automated image capturing, registration, reprojection and blending. The methods considered appropriate for further use are evaluated in the form of a series of tests developed for the purpose with focus on the balance between robustness, which ultimately means visual accuracy in the final image, and computation intensity. The techniques evaluated are based on feature points which are used to calculate a transformation homography. Also, two new techniques are presented and evaluated. One for finding features in the form of corners by approximating shapes into polygons. The other method is used to speed up the image matching process from a camera feed towards a given image by reducing the search space by using the former transient image from the camera feed. The results show that it is feasible to assemble correct image compositions despite that the intended sceneries often contain few features; a bigger problem is that they often are poorly distributed. The difference in quality between the corresponding evaluated techniques is small in comparison to the speed differences. With a combination of fast algorithms, including the proposed speed up, it is possible to achieve a holistic process working viable on standard mobile devices. To optimize the stitching process an alternative method is proposed utilising dynamic criteria for when a new image should be stored during the automated capturing.
Digitala anteckningar har flera fördelar gentemot analoga, men viljan att använda penna och papper kvarstår. Därmed uppkommer ett behov av att digitalisera handskrivna anteckningar. För att det ska vara så enkelt som möjligt är målet minsta möjliga antal interaktioner med användaren. Syftet med projektet är att presentera en process för automatiserad bildtagning för bilder tagna av en kamera som flyttas parallellt med en whiteboardtavla, eller liknande scenbild, följt av en process för automatisk sammanfogning av dessa bilder. Problemet ligger i behovet av att få högre kvalitet i den slutgiltiga bilden än vad som är möjligt med enbart en övergripande bild. Processerna ska exekveras på mobila enheter, med jämförelsevis låg beräkningskapacitet, inom ett rimligt tidsintervall. En genomgång och teoretisk analys utförs av befintliga metoder för alla delar av processen: automatiserad bildtagning, registrering, omprojecering samt färgutjämning. De metoder som bedöms ändamålsenliga utvärderas vidare i form av en serie tester utvecklade för ändamålet där fokus ligger på avvägningen mellan robusthet, vilket i förlängningen innebär visuell korrekthet i den slutgiltiga bilden, samt beräkningsintensitet. Teknikerna som utvärderas baseras på intressepunkter vilka används för att beräkna en omvandlingshomografi. Även två nya tekniker presenteras och utvärderas. Den ena för att hitta intressepunkter i form av hörn genom att approximera former till polygoner. Den andra metoden används för att snabba upp matchningsprocessen från ett kameraflöde mot en given bild genom att minska sökrymden med hjälp av föregående bild från kameraflödet. Resultaten visar att det är möjligt att foga samman korrekta bildkompositioner trots att de avsedda scenbilderna ofta innehåller få intressepunkter; ett större problem är att de ofta har dålig spridning. Skillnaden i bildkvalitet mellan de utvärderade teknikerna är små i jämförelse med hastighetsskillnaderna. Med en kombination av snabba algoritmer, inklusive den föreslagna uppsnabbningen, är det möjligt att åstadkomma en helhetsprocess som fungerar dugligt på vanliga mobila enheter. För att optimera bildsammanfogningen föreslås en alternativ metod med dynamiska kriterier för när en ny bild ska sparas under den automatiserade bildtagningen.

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Armstrong, Christopher J. « Live Surface ». BYU ScholarsArchive, 2007. https://scholarsarchive.byu.edu/etd/1029.

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Live Surface allows users to segment and render complex surfaces from 3D image volumes at interactive (sub-second) rates using a novel, Cascading Graph Cut (CGC). Live Surface consists of two phases. (1) Preprocessing for generation of a complete 3D watershed hierarchy followed by tracking of all catchment basin surfaces. (2) User interaction in which, with each mouse movement, the 3D object is selected and rendered in real time. Real-time segmentation is ccomplished by cascading through the 3D watershed hierarchy from the top, applying graph cut successively at each level only to catchment basins bordering the segmented surface from the previous level. CGC allows the entire image volume to be segmented an order of magnitude faster than existing techniques that make use of graph cut. OpenGL rendering provides for display and update of the segmented surface at interactive rates. The user selects objects by tagging voxels with either (object) foreground or background seeds. Seeds can be placed on image cross-sections or directly on the 3D rendered surface. Interaction with the rendered surface improves the user's ability to steer the segmentation, augmenting or subtracting from the current selection. Segmentation and rendering, combined, is accomplished in about 0.5 seconds, allowing 3D surfaces to be displayed and updated dynamically as each additional seed is deposited. The immediate feedback of Live Surface allows for the segmentation of 3D image volumes with an interaction paradigm similar to the Live Wire (Intelligent Scissors) tool used in 2D images.

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Parker, Emily M. « Surface active polymers as anti-infective and anti-biofouling materials ». Thesis, University of Oxford, 2012. http://ora.ox.ac.uk/objects/uuid:54e462df-b64c-499c-94ce-55d624be9a69.

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This thesis is concerned with the chemical modification of polymers in the preparation of a library of materials which exhibit altered surface properties as a result of the surface chemical functionality, with particular emphasis on the development of materials that control biofouling and are antibacterial. Chemical modification of crosslinked polystyrene, in film and microsphere form, was carried out by carbene insertion followed by diazonium coupling. This provided access to a collection of materials with varying surface chemistry, whilst the bulk properties of the polystyrene substrates were maintained. Synthesis of the diaryldiazo and the diazonium salts used to perform the surface modifications is described, as well as the preparation and characterisation of the materials. Analysis of the ability of the materials to adsorb and bind the protein bovine serum albumin (BSA) is presented with data obtained from two methods of observation. Quartz Crystal Microbalance with Dissipation (QCM-D) and a protein assay based on the change in optical density of a BSA/PBS solution are used to demonstrate how the specific surface chemistry of the materials influences the ability to adsorb and bind protein. The behaviour of the materials was time dependent and was rationalised with respect to the surface water contact angle and the calculated parameters polar surface area and % polar surface area of the functional groups added to the surfaces. Finally, penicillin loaded materials were prepared and their antibacterial activity was tested against E. coli and S. aureus, demonstrating that the antibiotic is still active from within the polystyrene scaffold.

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Huang, Run. « High Precision Optical Surface Metrology using Deflectometry ». Diss., The University of Arizona, 2015. http://hdl.handle.net/10150/581252.

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Software Configurable Optical Test System (SCOTS) developed at University of Arizona is a highly efficient optical metrology technique based on the principle of deflectometry, which can achieve comparable accuracy with interferometry but with low-cost hardware. In a SCOTS test, an LCD display is used to generate structured light pattern to illuminate the test optics and the reflected light is captured by a digital camera. The surface slope of test optics is determined by triangulation of the display pixels, test optics, and the camera. The surface shape is obtained by the integration of the slopes. Comparing to interferometry, which has long served as an accurate non-contact optical metrology technology, SCOTS overcomes the limitation of dynamic range and sensitivity to environment. It is able to achieve high dynamic range slope measurement without requiring null optics. In this dissertation, the sensitivity and performance of the test system have been analyzed comprehensively. Sophisticated calibrations of system components have been investigated and implemented in different metrology projects to push this technology to a higher accuracy including low-order terms. A compact on-axis SCOTS system lowered the testing geometry sensitivity in the metrology of 1-meter highly aspheric secondary mirror of Large Binocular Telescope. Sub-nm accuracy was achieved in testing a high precision elliptical X-ray mirror by using reference calibration. A well-calibrated SCOTS was successfully constructed and is, at the time of writing this dissertation, being used to provide surface metrology feedback for the fabrication of the primary mirror of Daniel K. Inouye Solar Telescope which is a 4-meter off-axis parabola with more than 8 mm aspherical departure.

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Sharma, Priyanka. « Investigations of Titan's Topography and Surface Roughness ». Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/241978.

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Saturn's moon, Titan is a geomorphologically active planetary object, and its surface is influenced by multiple processes like impact cratering, fluvial and aeolian erosion, lacustrine processes, tectonics, cryovolcanism and mantling. Disentangling the processes that compete to shape Titan's landscape is difficult in the absence of global topography data. In this thesis, I utilize techniques in topographic statistics, fractal theory, study of terrestrial analogs and landscape evolution modeling to characterize Titan's topography and surface roughness and investigate the relative roles of surface processes in sculpting its landscape. I mapped the shorelines of 290 North Polar Titanian lakes using the Cassini Synthetic Aperture Radar dataset. The fractal dimensions of the shorelines were calculated via the divider/ruler method and box-counting method, at length scales of (1-10) km and found to average 1.27 and 1.32, respectively. The inferred power-spectral exponent of Titan's topography (β) was found to be ≤ 2, which is lower than the values obtained from the global topography of the Earth or Venus. In order to interpret fractal dimensions of Titan's shorelines in terms of the surficial processes at work, I repeated a similar statistical analysis with 114 terrestrial analogous lakes formed by different processes, using C-band radar backscatter data from the Shuttle Radar Topography Mission (SRTM). I found different lake generation mechanisms on Earth produce 'statistically different' shorelines; however, no specific set of processes could be identified for forming Titanian lake basins. Using the Cassini RADAR altimetry data, I investigated Titan's global surface roughness and calculated median absolute slopes, average relief and Hurst exponent (H) for the surface of Titan. I detected a clear trend with latitude in these roughness parameters. Equatorial regions had the smallest slopes, lowest values of H and smallest intra-footprint relief, compared to the mid-latitudes and polar regions of Titan. I used steady state models of relief generation (tectonic activity) and relief reduction (diffusive mass wasting and advective bedrock channel erosion) to generate synthetic landscapes and simulate Titan's topography. I provided constraints on two environmental variables for Titan that influence surface roughness: diffusivity and erodibility coefficient.

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Moore, Kathleen Dorothy. « The Impact of Surface Normals on Appearance ». W&M ScholarWorks, 2016. https://scholarworks.wm.edu/etd/1477068344.

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The appearance of an object is the result of complex light interaction with the object. Beyond the basic interplay between incident light and the object's material, a multitude of physical events occur between this illumination and the microgeometry at the point of incidence, and also beneath the surface. A given object, made as smooth and opaque as possible, will have a completely different appearance if either one of these attributes - amount of surface mesostructure (small-scale surface orientation) or translucency - is altered. Indeed, while they are not always readily perceptible, the small-scale features of an object are as important to its appearance as its material properties. Moreover, surface mesostructure and translucency are inextricably linked in an overall effect on appearance. In this dissertation, we present several studies examining the importance of surface mesostructure (small-scale surface orientation) and translucency on an object's appearance. First, we present an empirical study that establishes how poorly a mesostructure estimation technique can perform when translucent objects are used as input. We investigate the two major factors in determining an object's translucency: mean free path and scattering albedo. We exhaustively vary the settings of these parameters within realistic bounds, examining the subsequent blurring effect on the output of a common shape estimation technique, photometric stereo. Based on our findings, we identify a dramatic effect that the input of a translucent material has on the quality of the resultant estimated mesostructure. In the next project, we discuss an optimization technique for both refining estimated surface orientation of translucent objects and determining the reflectance characteristics of the underlying material. For a globally planar object, we use simulation and real measurements to show that the blurring effect on normals that was observed in the previous study can be recovered. The key to this is the observation that the normalization factor for recovered normals is proportional to the error on the accuracy of the blur kernel created from estimated translucency parameters. Finally, we frame the study of the impact of surface normals in a practical, image-based context. We discuss our low-overhead, editing tool for natural images that enables the user to edit surface mesostructure while the system automatically updates the appearance in the natural image. Because a single photograph captures an instant of the incredibly complex interaction of light and an object, there is a wealth of information to extract from a photograph. Given a photograph of an object in natural lighting, we allow mesostructure edits and infer any missing reflectance information in a realistically plausible way.

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Sabio, Darlene Danette. « Surface Characteristics of Bacillus Spores ». VCU Scholars Compass, 2004. http://hdl.handle.net/10156/1715.

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Fremont, Julien. « Etude des contributions aux surfaces de potentiel et couplages non-adiabatiques par calculs ab initio de structures électroniques et mise aux points des Hamiltoniens effectifs pour les prédictions vibrationnelles : applications aux molécules LiH, H+3 et PH3 ». Reims, 2010. http://theses.univ-reims.fr/sciences/2010REIMS019.pdf.

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Ce travail se place à mi chemin entre chimie théorique et spectroscopie moléculaire théorique en proposant d’exploiter à leur maximum les méthodes de chimie quantique pour ensuite réaliser des prédictions théoriques sur les trois molécules LiH, PH3 et H3+. Dans un premier temps, un chapitre est consacré aux méthodes de chimie quantique utilisées dans ce travail et permettant d’obtenir les surfaces d'énergie potentielle et états électroniques. Pour les applications en spectroscopie moléculaire, la surface d'énergie potentielle nécessite une grande précision. Le second chapitre étudie l’influence de la base de calcul, des corrélations électroniques, des corrections relativistes et des méthodes d’extrapolation sur les niveaux vibrationnels de la molécule LiH. Pour une molécule possédant un faible nombre d'électrons, il est possible d'obtenir des précisions sur la surface d'énergie potentielle telle que l'approximation de Born-Oppenheimer est mise en défaut. Le troisième chapitre développe les notions de transformation de contact et Hamiltonien effectif. Il introduit les termes issus des calculs de chimie quantique nécessaires, pour finalement appliquer ce formalisme hors approximation de Born-Oppenheimer à la molécule LiH. L'objectif de ces deux précédents chapitres est d'explorer les limites des précisions offertes par les méthodes ab-initio pour caractériser les états vibrationnels de l'ensemble des isotopologues près de la dissociation. L'étude des molécules possédant un grand nombre de variables présente d'autres types de difficultés. Le grand nombre d’électrons d'une part rend difficile les calculs de chimie quantique pour l'obtention de surface d'énergie potentielle de bonne qualité, d'autre part l'augmentation du nombre de variables nucléaires complexifie les fonctions d'onde et par conséquent le calcul des niveaux d'énergie vibrationnelle. Le quatrième chapitre propose l'étude dans le cadre de Born-Oppenheimer de la molécule PH3 contenant la dérivation de l'opérateur d'énergie cinétique en coordonnées de valences et le calcul de la surface d'énergie potentielle par méthode chimie quantique. Les symétries de l'Hamiltonien moléculaire produisent des effets encore mal compris des scientifiques. La molécule H3+ dans sa configuration C3v possède une intersection conique où les effets non-adiabatiques sont révélés. Dans ce dernier chapitre l'opérateur d'énergie cinétique en coordonnées hyperspheriques ainsi que la matrice Jacobienne associée à cette transformation sont dérivés. Les couplages non-adiabatiques calculés en coordonnées cartésiennes sont réexprimés en coordonnées hypersheriques. Après avoir présenté la transformation adiabatique-diabatique, les effets de phase géométrique sont étudiés
This work takes place at the halfway between theoretical chemistry and theoretical molecular spectroscopy by proposing to use at their limits the quantum chemistry methods and then make theoretical predictions on the three molecules LiH, PH3 and H3 +. First of all, a chapter is devoted to quantum chemistry methods used in this work to obtain the potential energy surfaces and electronic states. For applications in molecular spectroscopy, the potential energy surface requires to be very accurate. The second chapter examines the influence of the basis, electronic correlations, relativistic corrections and extrapolation methods on the vibrational levels of LiH molecule. For a molecule with a small number of electrons, it is possible to get such quality on the potential energy surface that the limit the Born-Oppenheimer approximation is reached. The third chapter develops the concepts of contact transformation and effective Hamiltonian. It introduce the terms derived from quantum chemistry calculations needed to finally apply this formalism beyond the Born-Oppenheimer approximation to the LiH molecule. The aim of these two preveiws chapters is to explore the limits of ab-initio methods to characterize the vibrational states of all isotopologues near to the dissociation. The study of molecules with a large number of variables has other types of difficulties. The large number of electrons on one hand makes difficult to quantum chemistry calculations to obtain potential energy surface of good quality, on the other hand, the increase in the number of variables complicates the nuclear wave functions and therefore the calculation of vibrational energy levels. The fourth chapter presents the study within the framework of Born-Oppenheimer of the PH3 molecule containing the derivation of the kinetic energy operator in valence coordinates and calculating the potential energy surface by quantum chemistry method. The molecular symmetries of the Hamiltonian produces effects still poorly understood by scientists. The H3 + molecule in its C3v configuration has a conical intersection where the non-adiabatic effects are revealed. In this final chapter the kinetic energy operator in hyperspherical coordinates and the Jacobian matrix associated with this transformation are derived. The non-adiabatic couplings calculated in Cartesian coordinates are reexpressed hypersheriques. After introducing the adiabatic-diabatic transformation, the geometric phase effects are studied

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Stievano, Lorenzo. « Petit Voyage vers la surface : Structure et réactivité de solides inorganiques ». Habilitation à diriger des recherches, Université Pierre et Marie Curie - Paris VI, 2005. http://tel.archives-ouvertes.fr/tel-00092493.

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Dans ma carrière, j'ai eu la chance et le privilège de m'attaquer à des problématiques scientifiques très variées, qui peuvent être ressemblées par le concept fédérateur de l'application de méthodes d'analyses physico-chimiques pour la compréhension de la structure et de la réactivité d'un matériau inorganique. Parmi les techniques d'analyse que j'ai utilisées, une place d'honneur doit sûrement être attribuée à la spectroscopie Mössbauer, qui a été la technique principale d'analyse de ma thèse et qui a continué jusqu'aujourd'hui, à travers différentes collaborations, à faire partie de mes intérêts. Les types principaux de matériaux étudiés sont les suivants :

1. Matériaux d'intérêt historique
En parallèle avec mes études de thèse, je me suis intéressé à la caractérisation de trois classes de matériaux inorganiques d'intérêt historique : des céramiques archéologiques, des faïences et des verres rouge rubis à l'or.
Dans le cas des céramiques archéologiques, ce travail à permis de mieux comprendre les propriétés de certaines céramiques anciennes et de reconstruire leur méthode de fabrication. Ces informations sont fondamentales pour les archéologues pour étudier le degré d'avancement et les connaissances de civilisations anciennes.
Dans le cas des verres rouge rubis à l'or, notre travail a permis de clarifier quel est l'état chimique de l'or dans le verre avant l'apparition de la coloration rouge, et de mieux comprendre le rôle chimique d'adjuvants tels que l'oxyde d'étain ou d'antimoine, connus pour influencer la vitesse d'apparition de la couleur et la teinte finale du verre.
Enfin, dans l'étude des faïences, nous avons pu, par le biais de répliques obtenues en suivant des recettes anciennes, clarifier les évènements chimiques lors de l'obtention d'un émail blanc à base d'oxyde d'étain. Ces connaissances nous ont permis par la suite d'étudier convenablement des faïences anciennes.

2. Matériaux d'intérêt catalytique
A partir de mes études de thèse, en participant à des collaborations scientifiques avec différents groupes de recherche, j'ai pu contribuer au développement de plusieurs types de catalyseurs : la majorité de ces matériaux consistait en des catalyseurs à base de métaux supportés, et ma contribution était surtout liée à leur caractérisation structurale, souvent réalisée in situ. Dans certains cas, toutefois, j'ai participé aussi au développement de nouvelles méthodes de synthèse (entre autres, la mise au point d'un système de préparation de catalyseurs bimétalliques modèles par vaporisation laser et la préparation de catalyseurs bimétalliques par dépôt de clusters bimétalliques préformés) et, dans un cas, à l'étude d'activité catalytique des matériaux synthétisés (étude cinétique en hydrogénation du toluène et en hydrogénation de la tétraline en présence du soufre des catalyseurs Pd-Pt/Al2O3 préparés par vaporisation laser.)

3. Surfaces et interfaces
Mon initiation aux surfaces et aux interfaces a débuté déjà pendant ma thèse, avec deux études : la première portait sur l'étude de nanoparticules d'or englobées dans une matrice de mylar, n'interagissant pas avec cette dernière ; la deuxième concernait l'adsorption d'un complexe d'or monovalent avec la thio-urée dans la porosité de solides différents. Dans le premier cas, nous avons pu détailler les propriétés électroniques de la surface nue des nanoparticules d'or, alors que dans la deuxième étude nous avons montré que ce complexe peut être utilisé, en combinaison avec la spectroscopie Mössbauer de 197Au, comme sonde pour étudier la force des liaisons hydrogène avec des surfaces de nature différente.
Ensuite, en intégrant le groupe du Prof. J.-F. Lambert au Laboratoire de Réactivité de Surface, j'ai pu affiner mes connaissances sur la chimie aux interfaces, en suivant trois axes thématiques de recherche : la première thématique est le dépôt en phase vapeur de complexes de métaux de transition comme méthode alternative dans la préparation d'un catalyseur. Dans ce cadre, nous avons pu mettre en évidence, au niveau moléculaire, le mécanisme d'interaction entre un complexe de nickel et une surface d'oxyde, sans la médiation d'un solvant.
La deuxième thématique concernait la préparation d'argiles à pilier ferriques en utilisant une approche originale, le pontage par l'intercalation de polycations de structure précisément définie stabilisés par un agent complexant organique. Dans ce cadre, nous avons pu détailler au niveau moléculaire l'adsorption d'un polycation ferrique (Fe8-tacn) entre les feuillets d'une saponite naturelle.
La dernière parmi ces trois thématiques, résumée dans le paragraphe suivant, est devenue maintenant le sujet porteur de ma recherche actuelle et qui sera développé dans le futur.

4. L'interface entre matériau inorganique et petites molécules biologiques
L'étude systématique de l'adsorption d'acides aminés et d'oligopeptides sur des surfaces peut avoir une grande importance fondamentale et pratique dans plusieurs domaines, tels que la chimie prébiotique, la synthèse de polypeptides à l'état solide, en chromatographie et dans la fabrication de matériaux hybrides organiques/inorganiques. De plus, l'étude de l'adsorption de polypeptides peut fournir des modèles pour l'étude de l'adsorption de protéines (polypeptides de masse moléculaire élevée), ce qui est en effet un problème de grande importance appliquée.
Dans ce cadre, nous avons entrepris une étude systématique de l'adsorption d'acides aminés et oligopeptides sur des surfaces d'oxyde, mettant l'accent sur la compréhension moléculaire des phénomènes impliqués. Du point de vue méthodologique, nous avons décidé de coupler deux approches complémentaires : une approche expérimentale, en utilisant toute une batterie de techniques physico-chimiques disponibles au LRS, et une approche théorique, qui nous a permis de modéliser les sites d'adsorption, et de les valider en comparant les paramètres spectroscopiques calculés avec les résultats expérimentaux.
Cette stratégie, novatrice par rapport aux études précédentes sur ce sujet, nous a fourni un modèle moléculaire précis de la glycine adsorbée et de son interaction avec un site d'adsorption spécifique en surface de la silice.
Nous comptons maintenant faire évoluer ce sujet en envisageant une étude intégrée et systématique de l'adsorption de molécules biologiques selon trois axes de complexité indépendants (complexité des surfaces, complexité du milieu et complexité des adsorbats), tout en mettant l'accent sur la compréhension moléculaire des phénomènes impliqués.

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Gunnarsson, Sarius Niklas. « Surface Technology for Optical and Electrical Connectors ». Doctoral thesis, Linköpings universitet, Tunnfilmsfysik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-63626.

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This thesis treats surface engineering with the purpose of improved quality of optical and electricalconnectors with a focus on electroplated and magnetron sputtered materials. In electroforming of tools formanufacturing optical connectors, the influence of ultrasonic agitation on intrinsic stresses and fillingproperties of electroplated Ni has been studied. It is established that the ultrasonic agitation at the substratesurface during deposition impacts the intrinsic stresses making it possible to increase deposition rate viacurrent density, with stress-free or low-stress levels in the Ni layers. Reduced variations of the intrinsicstress over the surface with the current density is a further important result. Filling of grooves byelectroplating of Ni using ultrasonic agitation is demonstrated. This is due to increasing mass transport ofspecies into the grooves compared to conventional pumped agitation. The enhanced filling propertiesmakes it possible to electroplate Ni in the bottom of high-aspect-ratio grooves. In order to industriallyimplement new nanocomposite coatings on electronic connectors, studies have been performed regardingthe thermal diffusion barrier properties against Cu for Ti-Si-C and Ti-Si-C-Ag nanocomposites, depositeddirectly onto Cu substrates or with sputtered Ni, Ti or electroplated Ni as an intermediate coating. Theapplication of an electroplated Ni diffusion barrier coating, hinders Cu from reaching the surface of thenanocomposites. Also, Ti-Si-C-Ag nanocomposite deposited on magnetron sputtered Ni or Ti on Cusubstrates hinder Cu from diffusing to the surface after annealing. The contact resistance of Ag-Pdtopcoated Ti-Si-C-Ag-Pd and Ti-Si-C-Ag nanocomposite coatings in contact with hard gold is shown tocompete with hard gold in contact with itself, as electrical contact coatings at contact forces around 5 N.Ag-Pd topcoated Ti-Si-C-Ag-Pd in contact with hard gold is shown to have approximately the same contactresistance as hard gold in contact with hard gold at contact forces around 0.1 N, which here is in the 10 mΩrange, while Ti-Si-C-Ag nanocomposite coatings in contact with hard gold has a contact resistance that isup to 10 times higher. The overall contribution of this thesis can be summarised as a deeper knowledge andunderstanding of techniques and coatings, that help reduce cost and increase reliability of electronics.

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Bolin, Maria. « Conjugated Polymer Surface Switches for Active Control ». Doctoral thesis, Linköpings universitet, Institutionen för teknik och naturvetenskap, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-71361.

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Conjugated polymers have been found useful in a wide range of applications such as sensors, electrochemical transistors, solar cells, and printed electronics due to their mechanical, optical and electronic properties. An amazing research field has grown during the last three decades since the discovery of conducting polymers in 1976. Since the materials can be made from solutions, different processing methods such as spin coating and vapor phase polymerization can be used to coat a huge variety of substrates. The choice of method depends mainly on monomer solubility and kind of substrate to be coated. During the synthesis the polymers can be chemically modified to tailor their functionalities. Due to this variability in materials and the processability, electronics can be achieved on unconventional substrates such as flexible plastic foils and cell culturing dishes. As a contrast to inorganic, usually metallic materials, conducting polymers are built up from organic compounds in a molecular structure with soft mechanical properties that have shown to be a benefit in combination with biology, ranging from interactions with cells to interactions with advanced biological species such as tissues. This combination of research fields and the possible applications are merged within the field of organic bioelectronics. The primary purpose of this thesis is to give a background to organic electronics in general and how electrochemical devices can be processed and developed for biological applications in particular. An organic electronic surface switch is introduced to control cell adhesion and proliferation as well as an electrochemical transistor to spatially tune the cell adhesion along an electrochemical gradient. To mimic a more natural cell environment a three dimensional fiber substrate was used to design an electronically active matrix to promote nerve cell adhesion and communication. By combining standard microfabrication techniques and conjugated polymers desired patterns of electroactive polymer were created to enable active regulation of cell populations and their extracellular environment at high spatial resolution. Finally, a brief look into future challenges will also be presented.

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Razy, Alissa. « Synoptic analysis of cold-season surface wind regimes in Montreal ». Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=95056.

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We analyze the phenomenon of wind channeling, defined as dynamically- and thermally-induced processes that force the wind to blow along a valley's axis, for the region of Montreal (CYUL). CYUL lies at the focus of three valleys (the St. Lawrence River Valley, Lake Champlain Valley, and Ottawa River Valley), and these valleys each play a role in the observed distribution of wind directions at CYUL. Both the prediction and the effects of this channeling are non-trivial. This study identifies distinct synoptic patterns associated with the various surface wind regimes for instances of channeling, sustained for at least 12 hours, and for shorter periods. We also analyze the sensible weather impacts associated with sustained wind channeling. The results presented here are beneficial to the operational meteorologist in preparing forecasts and issuing weather warnings or advisories to the public.
Nous analysons le phénomène de canalisation du vent, défini comme des processus induits dynamiquement et thermiquement qui forcent le vent à souffler le long de l'axe d'une des vallées, pour la région de Montréal (CYUL). CYUL est au centre de trois vallées (la vallée du fleuve Saint-Laurent, la vallée du lac Champlain et la vallée de l'Outaouais), et ces vallées jouent chacune un rôle dans la distribution des directions du vent observée à CYUL. La prédiction ainsi que les effets de cette canalisation du vent ne sont pas aisés. Cette étude identifie les différents schémas synoptiques associés à différents régimes de vent de surface pour les instances de canalisation, maintenue pendant au moins 12 heures, et pour des périodes plus courtes. Nous analysons également les impacts météorologiques sensibles associés avec le maintient de la canalisation de vent. Les résultats présentés ici sont bénéfiques pour le météorologue opérationnel dans la préparation des prévisions et l'émission d'avertissements météorologiques ou d'avis au public.

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Liu, Ganming. « Hydrologic Response of Surface Waters in the Prairie Pothole Region to Climate Variability ». The Ohio State University, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=osu1313170630.

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Smith, Randall William. « Investigations of the Air-Water Interface : A Structural Analysis of Metallic Surface Films and Aquatic Surface Films by Comparative Microscopy ». PDXScholar, 2015. https://pdxscholar.library.pdx.edu/open_access_etds/2306.

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The air-water interface is an important natural boundary layer that has been neglected as an area of environmental field research. This study establishes that comparative microscopy can be an effective environmental method, and establishes that the term metallic surface films, is a more accurate descriptor than iron oxide surface films. This research shows that surface films are complex, often with layered structure, serve as habitat for significant biota, and act as a point of mineralization to several transition metal elements including manganese, iron, copper, nickel and zinc. This study demonstrates that surface films form under several conditions and can have diverse morphology. Activity of biota, microbes, particularly diatoms, suggests that bacteria and cyanobacteria integrate into the film often in patches, represented by forms and casts. Analytical imaging is used to document and compare film morphology and structures, using scanning electron microscopy, photoemission electron microscopy and transmission electron microscopy with elemental analysis by energy dispersive spectroscopy to confirm the hypothesis. Instrument parameters and strengths are reviewed. Component layers of a copper/zinc film were used to confirm metallic layers and elemental distribution. Bacterial casts were used to confirm film interaction, and to show entrainment and enrichment of the film to incorporate autochthonous and allochthonous materials into the films themselves. Most samples were from Oregon selected sites, with some samples from Maryland and Barbados.

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Park, Shinju. « On the estimation of near-surface atmospheric refraction uing scanning radar ». Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=94913.

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Near-surface atmospheric refraction, often characterized by the quantity refractivity, affects the propagation of the radar beam, yet it is poorly measured due to its complex pattern. The aim of this thesis is to characterize the structure of near-surface refractivity and its errors. The refractivity retrieval in the horizontal is obtained from the radar phase measurements that can be affected systematically by the variability of ground target heights over complex terrain coupled with propagation conditions. This study characterizes such factors statistically and reproduces the expected uncertainty (noisiness) by simulating phase for the assessment of the radar refractivity retrieval. However, the noisiness of simulated phase is much smaller compared with that of observations suggesting that such factors are incapable of characterizing moving ground targets and thus insufficient to fully explain the phase noisiness. The vertical structure of refractivity is, on the other hand, characterized in order to inform about low-level propagation conditions. The coverage of radar ground echo observed at low elevation angles is affected by the path of the radar beam determined with the vertical gradient of refractivity. Hence, this study simulates the coverage of ground targets with given vertical gradient of refractivity and compares it with the observed one. The best match between the simulation and observation is used to determine the radar estimate of refractivity changes in the vertical. The results are validated with the estimates from several sounding instruments. Although the identification of ground targets is required for better performance, this novel technique shows certain skill in extracting additional low-level atmospheric information out of radar measurements from ground targets. In both studies, the characterization of ground targets observed by radar plays a critical role: on one hand, it allows us to extract the structure of the near-ground refractivity
Près de la surface terrestre, la réfraction atmosphérique affecte la propagation des ondes radars. Cette caractéristique de l'atmosphère, qu'on nomme la réfractivité, est spatialement complexe et mal connue. Dans cette thèse, la structure de la réfractivité ainsi que ses erreurs sont caractérisés. La réfractivité est mesurée à partir du déphasage des échos radars provenant de cibles terrestres. Ce déphasage est une fonction de la complexité du terrain ainsi que des conditions de propagations. Ces deux facteurs sont analysés statistiquement afin de simuler l'incertitude attendue (le bruit) de la phase des échos radars affectant les mesures de réfractivité. Les simulations ainsi conduites possèdent un niveau de bruit sur la phase beaucoup plus petit que celui des mesures instrumentales. Cette observation suggère que le bruit sur la phase causé par le terrain et les conditions de propagation a un impact limité sur les mesures de réfractivité comparé au bruit provenant d'autres sources tel que les cibles mobiles. Dans un deuxième temps, la structure verticale de la réfractivité est étudiée afin de déduire les conditions de propagation en basse altitude. L'étendue des échos de sol observés à faibles élévations est affectée par la trajectoire des ondes radars qui à son tour est affectée par le gradient vertical de la réfractivité. Cette étude simule l'étendue des échos de sols en supposant différents gradients de réfractivité. Les gradients qui mènent à la meilleure ressemblance entre l'étendue des échos simulée et observée sont utilisés pour estimer les gradients réels de l'atmosphère. La validation des résultats est ensuite faite par comparaison avec d'autres instruments. Malgré le fait que les échos de sols doivent être identifiés pour une performance optimale, cette nouvelle technique démontre la possibilité d'inférer de nouvelles informations sur l'atmosphère en basse altitude à partir d'éch

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Eriksson, Kristofer. « Development and Applications of Surface-Confined Transition Metal Complexes : Heterogeneous Catalysis and Anisotropic Particle Surfaces ». Doctoral thesis, Stockholms universitet, Institutionen för organisk kemi, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-88215.

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The main focus of this thesis has been directed towards developing novel surface-confined transition metal complexes for applications in heterogeneous catalysis and for the preparation of anisotropic particle surfaces. The first part describes the heterogenization of a homogeneous transition metal-based catalyst tetraphenyl cobalt porphyrin (CoTPP) on silicon wafers and on silica particles. The activity in hydroquinone oxidation for the silica particle-immobilized CoTPPs was found to be increased 100-fold compared to its homogeneous congener whereas the silicon wafer-immobilized CoTPPs achieved lower activity due to the formation of clusters of catalyst molecules on the support surface as detected with atomic force microscopy (AFM). The second part of this thesis describes the development and characterization of anisotropic particle-surfaces by electrochemical site-specific oxidation of surface-confined thiols. Reactive patches or gold gradients could be obtained on the particle surfaces depending on the type of working electrode used and on the electrolyte composition. The particle surface functionalities were characterized with X-ray photoelectron spectroscopy (XPS) and the particle-surface-confined patches and gradients were conjugated with proteins to obtain fluorescence for investigation using fluorescence microscopy. Gold-functionalized siliceous mesocellular foams were further demonstrated to be highly efficient and selective catalysts in the cycloisomerization of 4-alkynoic acids to lactones. The final part of this thesis describes the preparation and characterization of palladium nanoparticles heterogenized in the pores of siliceous mesocellular foam. The nanoparticles were analyzed with transmission electron microscopy (TEM) and found to have a size of 1-2 nm. Primary- and secondary benzylic- and allylic alcohols were oxidized by the heterogeneous palladium nanoparticles in high to excellent yields using air atmosphere as the oxygen source. The nanopalladium catalyst was used up to five times without any decrease in activity and the size of the nanoparticles was retained according to TEM.

At the time of doctoral defence the following paper were unpublished and had a status as follows: Paper1: Manuscript; Paper 4: Manuscript

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Zhang, Wei. « Water overflow rage and bubble surface area flux in flotation ». Thesis, McGill University, 2010. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=86567.

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One of the most important factors that determines the concentrate grade in flotation is water recovery. Water recovery is influenced by frother through control of bubble size and possibly a frother-related chemical effect. A frother mass balance approach is presented for determining an equivalent water film thickness associated with bubble surface area flux exiting via the froth overflow to represent the chemistry effect.
A closed loop mini flotation cell setup is used to achieve steady state in continuous tests. Four frothers are evaluated to reveal the dependence of water overflow velocity (JwO) on frother type and concentration. Using Total Organic Carbon analysis, frother partitioning between overflow and underflow is measured, showing a remarkable preferential distribution to the overflow at low frother dosage. From surface tension measurements the Gibbs excess adsorption density (Г) is estimated and used in the mass balance approach to estimate bubble surface area flux to overflow (SbO). Estimations from this approach are compared with bubble surface area flux into and on top of froth obtained from bubble size data using image analysis. A correlation is shown between JwO and SbO permitting an equivalent water film thickness carried by the bubble into the overflow (δO) to be estimated. The δO reflects the frother type: a stronger frother creates a larger δO and a weaker frother creates a smaller δO. Possible implications in flotation are discussed.
Dans les machines de flottation, le recouvrement d'eau est l'un des facteurs les plus importants dans la détermination de la teneur en minerai du concentré. Le recouvrement d'eau est influencé par l'agent moussant qui contrôle la taille des bulles et interagit possiblement d'un point de vue chimique. Afin de mettre en évidence le caractère chimique de cette interaction, une approche basée sur le bilan massique de l'agent moussant est présentée. Celle-ci vise plus précisément à déterminer l'épaisseur moyenne du film d'eau associé à l'aire de surface du flux de bulles empruntant comme voie de sortie la partie supérieure de la mousse.
Une cellule de mini flottation dotée d'un circuit en boucle est utilisée afin d'atteindre un d'état d'équilibre stable lors des tests en continu. Quatre agents moussants font l'objet d'études afin de comprendre la relation existant entre la vélocité du flux d'eau sortant (JwO) et le type et/ou la concentration d'agent moussant. Avec la méthode d'analyse du Carbone Organique Total, il est possible de mesurer la répartition de l'agent moussant entre la partie supérieure et la partie inferieure de la mousse. Lorsque la concentration en agent moussant est faible, on remarque que l'agent moussant se concentre préférentiellement dans la partie supérieure de la mousse. A partir de mesures de tension superficielle, l'excès de la densité d'adsorption de Gibbs (Г) est évalué et inclus dans le bilan massique afin d'estimer l'aire de surface du flux de bulle dans la partie supérieure de la mousse (SbO). Ces estimations sont comparées avec les aires de surface des flux de bulles au centre et dans la partie supérieure de la mousse, obtenues à l'aide de la technique d'analyse d'images. Une corrélation obtenue, entre JwO et (δO) permet d'estimer une épaisseur équivalente de film d'eau transporté par la bulle dans la partie supérieure. Des épaisseurs comparables de film d'eau transporté par la bulle dans la partie supérieure de la mousse δO sont obtenues. Le δO est caractéristique du type d'agent moussant : dans le cas d'un fort agent moussant, δO est épais alors que dans le cas d'un faible agent moussant, δO est fin. De possibles conséquences engendrées en matière de flottation font l'objet d'une discussion. fr

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Moore, Sara. « An Investigation of How Surface Coal Mining Affects Water Quality ». Digital Commons @ East Tennessee State University, 2010. https://dc.etsu.edu/honors/5.

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Surface coal mining has become the ideal method for extracting coal from the Appalachia Mountains. However, surface coal mining generates large amounts of waste which may decrease the water quality in central Appalachia. This research is an attempt to determine whether surface coal mining negatively impacts water quality. This research consists of a literature review in addition to an analysis of data obtained through the Virginia Department of Environmental Quality. This data was analyzed at three separate locations along the Clinch River, VA to determine trends and cycles in pH, temperature, total hardness, and chloride, sulfate and metal concentrations. After analysis of data, it was concluded surface mining did not negatively impact water quality at these three locations. In addition, more research must be done to make a more accurate, concise conclusion between water quality and surface mining.

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Beauchat, Tracey Allen. « Analysis of (iso)surface reconstructions : Quantitative metrics and methods ». W&M ScholarWorks, 1996. https://scholarworks.wm.edu/etd/1539623885.

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Due to sampling processes volumetric data is inherently discrete and most often knowledge of the underlying continuous model is not available. Surface rendering techniques attempt to reconstruct the continuous model, using isosurfaces, from the discrete data. Therefore, it natural to ask how accurate the reconstructed isosurfaces are with respect to the underlying continuous model. A reconstructed isosurface may look impressive when rendered ("photorealism"), but how well does it reflect reality ("physical realism")?;The users of volume visualization packages must be aware of the short-comings of the algorithms used to produce the images so that they may properly interpret, and interact with, what they see. However, very little work has been done to quantify the accuracy of volumetric data reconstructions. Most analysis to date has been qualitative. Qualitative analysis uses simple visual inspection to determine whether characteristics, known to exist in the real world object, are present in the rendered image. Our research suggests metrics and methods for quantifying the "physical realism" of reconstructed isosurfaces.;Physical realism is a many faceted notion. In fact, a different metric could be defined for each physical property one wishes to consider. We have defined four metrics--Global Surface Area Preservation (GSAP), Volume Preservation (VP), Point Distance Preservation (PDP), and Isovalue Preservation (IVP). We present experimental results for each of these metrics and discuss their validity with respect to those results.;We also present the Reconstruction Quantification (sub)System (RQS). RQS provides a flexible framework for measuring physical realism. This system can be embedded in existing visualization systems with little modification of the system itself. Two types of analysis can be performed; reconstruction analysis and algorithm analysis. Reconstruction analysis allows users to determine the accuracy of individual surface reconstructions. Algorithm analysis, on the other hand, allows developers of visualization systems to determine the efficacy of the visualization system based on several reconstructions.

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Aharonson, Oded 1973. « The surface of Mars : morphology and process ». Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/8056.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2002.
Includes bibliographical references (p. 119-136).
The goal of this work is a quantitative description of the morphology of the surface of Mars, in order to constrain the nature of processes acting during the ancient past through today. Emphasis is placed on linking geometric properties to physical mechanisms. Surface smoothness on Mars is distinctive in the vast northern hemisphere plains. Amazonis Planitia is remarkable in its smoothness, exhibiting an rms variation in topography of < 2 m over a 100-km baseline, that is most comparable to planetary surfaces that are depositional in origin. The region of concentrated hematite mineralization in Sinus Meridiani is also relatively smooth, but neither region forms a closed basin. Mars' slope distribution is longer tailed than those of Earth and Venus, indicating a lower efficiency of planation processes relative to relief-building tectonics and volcanics. The shallower long-wavelength portion of the lowlands' topographic power spectrum relative to the highlands' can be accounted for by a simple model of sedimentation such as might be expected at an ocean's floor, but the addition of another process such as cratering is necessary to explain the spectral slope in short wavelengths. Large drainage systems on Mars have geomorphic characteristics that are inconsistent with prolonged erosion by surface runoff. We find the topography has not evolved to an expected equilibrium terrain form, even in areas where runoff incision has been previously interpreted.
(cont.) We demonstrate that features known as slope streaks form exclusively in regions of low thermal inertia, steep slopes, and incredibly, only where daily peak temperatures exceed 275 K during the martian year. The results suggest that at least small amounts of water may be currently present and undergo phase transitions. We detect subtle changes of the polar surface height during the course of seasonal cycles. Using altimetric crossover residuals, we show that while zonally averaged data captures the global behavior of CO2 exchange, there is a strong dependence of the pattern on longitude. Decomposition of the signal into harmonics in time shows the amplitudes are correlated with the polar cap deposits.
by Oded Aharonson.
Ph.D.

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Goodman, Daniel Hayim. « Aware surfaces : large-scale, surface-based sensing for new modes of data collection, analysis, and human interaction ». Thesis, Massachusetts Institute of Technology, 2015. http://hdl.handle.net/1721.1/98643.

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Thesis: S.M., Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2015.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 152-158).
This thesis describes the design and construction of pressure sensing matrices for capturing human location and activity data from large surfaces in a space such as the floors, walls, tabletops, countertops, and furniture. With the ability to operate either alone or connected to others in an assembly, each sensor module is 0.3m x 2m, contains 512 force sensitive resistors, and has a refresh rate of about 8Hz. Each module was made with conductive inkjet printing and PCB fabrication, creating a low-profile sensing surface with robust signal-collecting circuitry. Several experiments were conducted on an assemblage of three modules to assess parameters such as response time, sensitivity, measurement repeatability, spatial and pressure resolution, and accuracy in analyzing walking data as compared to a camera. Applications that could employ such a system are explored and two visualizations were prototyped that could ambiently provide data and trends to a user.
by Daniel Hayim Goodman.
S.M.

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Van, Sinay Olivier W. J. « Etude de la composition de surface d'alliages NiRh ». Doctoral thesis, Universite Libre de Bruxelles, 1998. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/212031.

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Ruckert, Danielle. « Modification de surface de polymeres par greffage photochimique ». Doctoral thesis, Universite Libre de Bruxelles, 1994. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/212698.

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Zipser, Karl. « A role for striate cortex in surface perception ». Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/32680.

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Elloway, Edward A. G. « Acanthamoebal surface properties and the modulation of phagocytosis ». Thesis, Aston University, 2002. http://publications.aston.ac.uk/10946/.

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The surface nature of Acanthamoeba trophozoites and cysts was investigated with respect to cell surface charge, hydrophobicity and surface carbohydrate composition. Particulate microelectrophoresis revealed a marked negative charge for both morphological forms, though less for cyst surfaces. Hydrophobicity was determined by adhesion to n-hexadecane and indicated a relatively low hydrophobic nature of both forms, though less so for cysts. Surface carbohydrate composition was studied by the use of fluorescent lectins and flow cytometry, using a ligand-receptor approach for further in depth analysis of binding of particular lectins. These studies showed trophozoite and cyst surfaces to be rich in N-acetylglucosamine, N-acteylneuraminic acid, mannose and glucose, with the addition of N-acetylgalactosamine on cysts. The importance of such surface properties was investigated with respect to phagocytosis of polystyrene latex microspheres, of different surface types and size. Investigations into the optimum conditions of uptake of beads indicated a preference for a medium devoid of nutrients, such as saline, though temperature was not a factor. An amoebal predilection for beads of lower charge and greater hydrophobicity was demonstrated. Furthermore, a preference for the largest bead size used (2.0 m) was observed. The influence of either Con A or mannose or glucose on bead association was apparently limited. The fate of foreign DNA ingested by Acanthamoeba appeared to indicate that such DNA was destroyed, as it could not be detected following extraction procedures and PCR amplification.

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Lamana, Thais. « Nickel sorption on calcite surface : a macroscopic experimental study ». Thesis, McGill University, 2011. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=97241.

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In natural aqueous systems, adsorption and co-precipitation (sorption) are regarded as possible metal sequestration mechanisms that would promote in situ passive remediation. Calcite is a ubiquitous mineral on the Earth's surface, whose propensity to scavenge trace metals has been extensively investigated. Since Nickel (Ni) appears on the EPA "priority list" of pollutants, identifying factors that may control its fate in calcite-rich natural waters (e.g. groundwaters, carbonate-rich coastal and marine sediments) is critical. Unfortunately, scarce literature is dedicated to the influence of mineral properties and solution chemistry on the affinity and sorption mechanisms of Ni on the calcite surface. With that in mind, batch sorption experiments were conducted, under controlled laboratory conditions (ambient temperature of 25 ± 2ºC, and atmospheric pCO2= 10-3.41atm) in calcite-saturated 0.1M and 0.7M NaCl solutions over a range of pH (7.5 to 8.9) and total Ni concentrations- [Ni]total- (1.2 x 10-4 to 3.5 x 10-6 M), to characterize the affinity of Ni for the calcite surface. Our experimental results revealed that the first 24 hours of reaction are critical to the metal-mineral interaction and the fractional Ni(II) sorption varied with solution pH and Ni(II) aqueous speciation. Notably, Ni sorption onto the calcite surface increased with pH and was well correlated to the relative abundance of the NiCO30(aq) species (ion-pair) over the pH range studied. After 24 hours, the overall Ni fractional sorption was attenuated with an increase of the background electrolyte (NaCl) concentration. The application of adsorption isotherm models (Langmuir and Freundlich) allowed us to highlight the dependence of adsorption to the [Ni]total and solution pH. Finally, irrespective of the solution ionic strength (0.1 and 0.7 M NaCl), Ni did not desorb readily when the total Ni(II) concentration in solution exceeded 4.0 x 10-5M.
Dans les systèmes aquatiques naturels, l'adsorption et la co-précipitation (sorption) sont considérés comme des processus passifs de séquestration in-situ des métaux lourds. La calcite est un minéral très abondant dans la croûte terrestre et un puits pour plusieurs métaux. Par conséquent, sa capacité de séquestration de métaux a été largement étudiée. Puisque le nickel (Ni) est considéré comme un polluant dangereux pour la santé humaine et environnementale, l'identification des facteurs qui peuvent contrôler son devenir dans les milieux naturels riches en calcite (eaux souterraines riches en carbonate ou sédiments côtiers et marins) est essentielle. Malheureusement, il y a peu de littérature pertinente sur l'influence des propriétés du minéral et la composition de la solution sur l'affinité et les mécanismes de sorption du Ni(II) à la surface de la calcite. Vu le manque d'information sur le sujet, nous avons mené une étude sous des conditions contrôlées en laboratoire (température ambiante de 25 (±2°C) et une pression partielle de CO2 = 10-3.41atm) dans des solutions aqueuses de NaCl saturées en calcite. Afin de caractériser l'affinité du Ni(II) pour la surface de la calcite, les expériences ont été effectuées dans des solutions de force ionique (0.1M et 0.7M), pH et concentration totale de Ni ([Ni]total) variées. Les résultats révèlent que les 24 premières heures de réaction sont critiques pour la sorption du Ni(II). La sorption du Ni(II) sur la calcite augmente avec le pH de la solution mais diminue avec l'augmentation de la concentration de NaCl. Indépendamment de la force ionique, la sorption fractionnelle du Ni est fortement corrélée avec l'abondance relative du complexe NiCO3o(aq) dans l'intervalle de pH étudié. Quelle que soit la force ionique (0.1M et 0.7M NaCl) de la solution, le Ni(II) ne se désorbe pas suite à son adsorption dans les solutions dont la concentration totale en Ni est supérieure à 4.0 x 10-5M.

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Jerry, Ruel (Ruel Valentine). « Effects of subsurface fracture interactions on surface deformation ». Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/84911.

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Thesis (S.M. in Geophysics)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2013.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 63-64).
Although the surface deformation resulting from the opening of a single fracture in a layered elastic half-space resembles the observed deformation at the InSalah site, it seems unlikely that only a single fracture is involved. This raises the question of how interaction among multiple fractures affects surface deformation. Finite element modeling is used to build a 3D model of a reservoir with multiple fractures. The interacting cracks and fractures give this model a more complicated stress state, and so any surface deformation would be different from that of a model with a single fracture. Geodetic monitoring of large-scale CO 2 sequestration provides a potentially powerful and cost-effective tool for interrogating reservoir structure and processes. For example, InSAR observations at the InSalah, Algeria sequestration site have mapped the surface deformation above an active reservoir, and helped delineate the effects of CO2 storage. The impact of interactions on individual fractures and the qualitative changes in the surface displacement and stress fields are considered and the importance of orientation, position and fracture area is investigated. It was found that when the crack locations are biased towards stacked parallel arrangements, then the shielding effect of interactions dominates, meaning that the overall stiffness of a representative volume increases. When collinear interactions dominate then the overall stiffness is reduced. These effects are then used to find a volume average and a continuum description of a solid with effective elastic properties. In this way a volume of fractured rock can be replaced with a representative volume with elastic properties that approximate the interaction effects.
by Ruel Jerry.
S.M.in Geophysics

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Gnanadesikan, Anand 1967. « Dynamics of Langmuir circulation in oceanic surface layers ». Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/52995.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1994.
Vita.
Includes bibliographical references (leaves 344-349).
by Anand Gnanadesikan.
Ph.D.

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Hayashi, Koichi 1967. « Variable grid finite-difference modeling including surface topography ». Thesis, Massachusetts Institute of Technology, 1999. http://hdl.handle.net/1721.1/9367.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, September 1999.
"August 6, 1999."
Includes bibliographical references (leaves 188-190).
We have developed a two-dimensional viscoelastic finite-difference modeling method for highly complex surface topography and subsurface structures. Realistic modeling of seismic wave propagation in the near surface region is complicated by many factors, such as strong heterogeneity, topographic relief and large attenuation. In order to account for these complications, we use a velocity-stress staggered grid and employ an 0(2,4) accurate viscoelastic finite-difference scheme. The implementation includes an irregular free surface condition for topographic relief and a variable grid technique in the shallow parts of the model. Several methods of free surface condition are bench marked, and an accurate and simple condition is proposed. In the proposed free surface condition, stresses are calculated so that the shear and normal stresses perpendicular to the boundary are zero. The calculation of particle velocities does not involve any specific calculations, and the particle velocities are set to zero above the free surface. A stable variable grid method is introduced, where we use a three times finer grid in the near surface or low velocity region compared to the rest of the model. In order to reduce instability, we apply averaging or weighting to the replacement of the coarse grid components within the fine grid. The method allows us to avoid any limitation of the shape of the grid size boundary. Numerical tests indicate that approximately ten grid-points per shortest wavelength with the variable grid method results in accurate calculations. The method requires a stair-shaped discretization of a free surface. We investigated the stair-shaped structures, and found that the cause of the dispersion from irregular free surface is mainly a numerical error due to the large grid sizes rather than the Rayleigh waves scattering due to the stair-shaped boundary. The finite-difference modeling is applied to the investigation of near surface wave propagation. Several numerical simulations are performed to show the characters of wave propagation in the near surface region. The simulations show that the low velocity thin layers just below the surface and anelastic attenuation have significant effect on surface seismic record. The 2-D modeling of near surface structure beneath a 2-D refraction survey line is carried out. The comparison of the observed data with theoretical waveforms is performed. The characters in the observed data can be explained by a subsurface model constructed by P-wave traveltime tomography.
by Koichi Hayashi.
S.M.

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34

Rodney, Marcel. « Subseasonal prediction of wintertime North American surface air temperature using the MJO signal ». Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=110747.

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A multi-variable linear regression model is constructed based on the status of the Madden-Julian oscillation (MJO) and persistence in order to forecast wintertime surface air temperature anomalies over North America out to 4 pentads (20 days). The current and previous states of the MJO are utilized as predictors, based on the Real-time Multivariate (RMM) indices of Wheeler and Hendon (2004). Modest skill is found, largely centred over the eastern United States and the Great Lakes. The model skill is seen to be highly dependent on the magnitude and phase of the MJO as well. Beyond the persistence driven 1st pentad, forecasts starting from MJO phases 3,4,7 and 8 that correspond to a dipole diabatic heating anomaly in the tropical Indian Ocean and western Pacific are more skillful during pentads 2 and 3 than those with other MJO phases at the initial time. The results are compared with the monthly hindcast of the Global Environmental Multiscale Model (GEM). The empirical method proves to be slightly superior to GEM beginning with pentad 3 south of the Great Lakes. This advantage expands and strengthens by pentad 4 throughout much of the eastern United States and into portions of western Canada.
Un modèle constitué d'une régression linéaire à plusieurs variables de l'indice d'oscillation de Madden-Julian (OMJ) et de la persistance est construit et employé dans le but de prévoir les anomalies de température de l'air en Amérique du Nord durant la saison hivernale. Ces prévisions, qui s'étalent sur une période de 20 jours (divisée en quatre intervalles de 5 jours, que l'on indiquera désormais par les indices I1 à I4, respectivement), sont fondées sur des données présentes et historiques entourant l'OMJ, analysées en fonction d'indices à multiples variables en temps réel "Real-time Multivariate indices (RMM)" (voir Wheeler et Hendon, 2004). La qualité des prévisions est plutôt modeste, et l'ensemble des résultats concluants se limitent principalement sur la portion est des États-Unis ainsi que la région des Grands Lacs; de plus, la performance du modèle semble correspondre avec l'intensité et la phase de l'OMJ. Hormis l'intervalle I1, où la qualité de prévision s'explique principalement par la persistance des anomalies, les simulations débutant aux phases 3, 4, 7 et 8 de l'OMJ liées à une anomalie dipolaire de chauffage diabatique dans la portion tropicale de l'Océan Indien et le Pacifique ouest démontrent une qualité de prévision accrue durant les intervalles I2 et I3 par rapport aux autres phases de l'OMJ. Les résultats sont également comparés avec le modèle de prévision Global Environnemental Multiéchelles (GEM), employé par Environnement Canada. La méthode empirique surpasse légèrement les simulations du GEM à partir de l'intervalle I3 au sud des Grands Lacs; lors du dernier intervalle I4, cet avantage se matérialise presque partout aux États-Unis, et couvre également une partie de l'Ouest Canadien.

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Coquelet, Hélène. « Transcription des gènes d'antigène de surface chez Trypanosoma brucei ». Doctoral thesis, Universite Libre de Bruxelles, 1990. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/213141.

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Foster, Alexander J. « Cell surface analysis of the basidiomycete yeast cryptococcus neoformans ». Thesis, Aston University, 2004. http://publications.aston.ac.uk/11011/.

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Cell surface properties of the basidiomycete yeast Cryptococcus neoformans were investigated with a combination of novel and well proven approaches. Non-specific cell adhesion forces, as well as exposed carbohydrate and protein moieties potentially associated with specific cellular interaction, were analysed. Experimentation and analysis employed cryptococcal cells of different strains, capsular status and culture age. Investigation of cellular charge by particulate microelectrophoresis revealed encapsulated yeast forms of C. neoformans manifest a distinctive negative charge regardless of the age of cells involved; in turn, the neutral charge of acapsulate yeasts confirmed that the polysaccharide capsule, and not the cell wall, was responsible for this occurrence. Hydrophobicity was measured by MATH and HICH techniques, as well as by the attachment of polystyrene microspheres. All three techniques, where applicable, found C. neoformans yeast to be consistently hydrophilic; this state varied little regardless of strain and culture age. Cell surface carbohydrates and protein were investigated with novel fluorescent tagging protocols, flow cytometry and confocal microscopy. Cell surface carbohydrate was identified by controlled oxidation in association with biotin hydrazide and fluorescein-streptavidin tagging. Marked amounts of carbohydrate were measured and observed on the cell wall surface of cryptococcal yeasts. Furthermore, tagging of carbohydrates with selective fluorescent lectins supported the identification, measurement and observation of substantial amounts of mannose, glucose and N-acetyl-glucosamine. Cryptococcal cell surface protein was identified using sulfo-NHS-biotin with fluorescein-streptavidin, and then readily quantified by flow cytometry.

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Gunnerek, Rasmus. « Fatigue behavior of Ti-6Al-4V alloys manufactured by Selective Laser Melting : Influence of microstructure, surface roughness and surface morphology ». Thesis, Karlstads universitet, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-67514.

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The intention of this thesis is to investigate the fatigue behavior of the Ti-6Al-4V alloy manufactured by the relatively new additive manufacturing process called Selective Laser Melting(SLM). SLM has been shown the interest from important industries such as the aerospace and biomedical industry for its potential of manufacturing lightweight and complex parts to net shape without the need of conventional methods like machining. Due to the short history of SLM there is little knowledge about how fatigue properties are influenced by the manufacturing process. This project aims to add to that knowledge by studying how the microstructure, surface roughness and surface morphology influences the fatigue life of SLM made Ti-6Al-4V alloys. Fatigue tests are done by conducting 3-point bending tests on SLM and conventional samples. It was found that the SLM samples only managed 9% of the fatigue life obtained for conventional samples. This was assumed to be caused by the poor surface roughness of SLM samples, acting as stress concentrations resulting in multiple crack nucleation leading to final fracture. It was also found that a surface morphology of 90°, relative to the length of the sample, had worse fatigue life compared to 60° and 30° due to the pattern of the sample being perpendicular to the applied load.

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Guo, Hua. « Bio-inspired surface engineering for hydrophobicity ». Thesis, Edith Cowan University, Research Online, Perth, Western Australia, 2014. https://ro.ecu.edu.au/theses/1013.

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Highly evolved, efficient and sophisticated biological systems can be used as models for scientific innovations. This research explored specific surface structures on plant leaves with respect to their hydrophobicity in the context of the often arid Australian climate. The relationships between leaf surface structures and their hydrophobicity could inform the making of artificial surfaces with specially designed hydrophobicity. Moderate hydrophobicity and strong surface adhesion were discovered on many study plant leaves. Scanning Electron Microscopy (SEM) revealed that their surface morphologies could be categorized into four groups while their water-repellent mechanisms were considered at an individual species level. Specifically, physical models were built based on the topography of several Eucalyptus species. Wetting robustness and surface free energy analyses were performed with these models to study wetting transitions on surfaces with specific microscopic features. In the fabrication component of the study, a convenient self-assembly procedure of oxysilane successfully converted a hydrophilic glass slide into a hydrophobic surface, with the measured contact angle changing from 30.8 to more than 1000. Atomic force microscope (AFM) images showed randomly distributed roughness at a micrometre scale on these self-assembled hydrophobic surfaces. Samples with square arrays of micro-posts were also fabricated following a sophisticated photo-lithography process. Wetting properties similar to some leaves, namely moderate hydrophobicity and strong surface adhesion, were observed with these fabricated samples. Anisotropic wetting, liquid-surface contact footprints and base lengths on these micro-textured surfaces were also investigated. Finally, fluorine containing diamond-like carbon (F-DLC) coatings were examined because of their chemical inertness, mechanical durability, and low surface energy. F-DLC films were prepared by closed-field, unbalanced, magnetron sputtering (CFUBMS) on silicon substrate to study their wetting and mechanical properties. The influences of CF4 and C2H2 gas addition during fabrication on these properties were explored by measuring contact angles, fluorine contents, surface roughness, Young's modulus and hardness. Simulation from Finite Element Analysis with COMSOL software was also conducted to confirm the mechanical results obtained in nano-indentation experiments. The leaf surface geometries revealed in this study could trigger further relevant research and applications. Surface free energy analysis on the built models could lead to a deeper theoretical understanding of wetting state transition for these geometries. The preliminary results on the self-assembly of oxysilane at ambient conditions could contribute to the development of cost-efficient and environmentally friendly methods for fabricating durable hydrophobic coatings. The results of F-DLC coatings could be beneificial for manipulating surface free energy and mechanical properties, to match specific requirements for certain applications.

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39

Wang, Haining. « Novel optical properties of metal nanostructures based on surface plasmons ». Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5720.

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Surface plasmons have been attracted extensive interests in recent decades due to the novel properties in nanometer sized dimensions. My work focused on the novel optical properties of metal nanostructures based on surface plasmons using theoretical simulation methods. In the first part, we investigated metal nanofilms and nanorods and demonstrated that extremely low scattering efficiency, high absorption efficiency and propagation with long distance could be obtained by different metal nanostructures. With a perforated silver film, we demonstrated that an extremely low scattering cross section with an efficiency of less than 1% can be achieved at tunable wavelengths with tunable widths. The resonance wavelength, width, and intensity are influenced by the shape, size and arrangement pattern of the holes, as well as the distance separating the holes along the polarization direction. The extremely low scattering could be used to obtain high absorption efficiency of a two-layer silver nanofilm. Using the discrete dipole approximation method, we achieved enhanced absorption efficiencies, which are close to 100%, at tunable wavelengths in a two-layer silver thin film. The film is composed of a 100 nm thick perforated layer facing the incident light and a 100 nm thick solid layer. Resonance wavelengths are determined by the distances between perforated holes in the first layer as well as the separation between two layers. The resonance wavelengths shift to red with increasing separation distance between two layers or the periodic distance of the hole arrays. Geometries of conical frustum shaped holes in the first layer are critical for the improved absorption efficiencies. When the hole bottom diameter equals the periodic distance and the upper diameter is about one-third of the bottom diameter, close to unit absorption efficiency can be obtained. We examined the electromagnetic wave propagation along a hollow silver nanorod with subwavelength dimensions. The calculations show that light may propagate along the hollow nanorod with growing intensities. The influences of the shape, dimension, and length of the rod on the resonance wavelength and the enhanced local electric field, |E|2, along the rod were investigated. In the second part, a generalized electrodynamics model is proposed to describe the enhancement and quenching of fluorescence signal of a dye molecule placed near a metal nanoparticle (NP). Both the size of the Au NPs and quantum yield of the dye molecule are crucial in determining the emission intensity of the molecule. Changing the size of the metal NP will alter the ratio of the scattering and absorption efficiencies of the metal NP and consequently result in different enhancement or quenching effect to the dye molecule. A dye molecule with a reduced quantum yield indicates that the non-radiative channel is dominant in the decay of the excited dye molecules and the amplification of the radiative decay rate will be easier. In general, the emission intensity will be quenched when the size of metal NP is small and the quantum yield of dye molecule is about unity. A significant enhancement factor will be obtained when the quantum yield of the molecule is small and the particle size is large. When the quantum yield of the dye molecule is less than 10-5, the model is simplified to the surface enhanced Raman scattering equation.
Ph.D.
Doctorate
Chemistry
Sciences
Chemistry

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Rozenbeek, Erik. « Surface reactivity of ultrathin atomic layer deposited Al2O3 on Li[Ni0.8Mn0.1Co0.1]O2 ». Thesis, Uppsala universitet, Institutionen för kemi - Ångström, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-416702.

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The nickel-rich cathode material Li[Ni0.8Mn0.1Co0.1]O2 is a much sought after material in Li-ion batteries for the future of electric vehicles due to its high specific capacity. However, it exhibits fast degradation during its use due to the interaction between the electrolyte and the cathode surface leading to capacity loss. In this thesis, the surface interaction of pristine and alumina coated NMC811, and NiO powder with electrolyte was investigated to observe difference in surface reactivity and if hydroxide groups on the surface could be a potential culprit in degradation. Thermogravimetric analysis (TGA) and Brunauer–Emmett–Teller (BET) analysis were used to measure thermal properties, surface area and adsorptive properties respectively between pristine and coated powders but no distinct difference was found. A soaking experiment was performed to induce electrolyte degradation on the powders by soaking them in the electrolyte LP40 for a duration of two weeks at 50°C. The electrolyte and the soaked powders were thereafter investigated through various spectroscopy methods like Attenuated Total Reflection – Fourier Transform Infrared (ATR-FTIR) and Raman spectroscopy to find potential degradation products but were found insignificant or inconclusive difference. The electrochemical testing was performed on NMC811 half-cells at 3-4.2V and 3-4.4V with a 0.5C – rate. The coated heat-treated NMC811 was found to have the best cyclability at both potential ranges. In conclusion, the difference in surface reactivity of the pristine, coated, and coated heat-treated powders were found to be insignificant. However, the coated heat-treated NMC811 was found to have improved electrochemical performance at both potential ranges but it remains uncertain if hydroxide groups could be a culprit in the degradation.

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41

Jin, Menglin. « Interpolation of surface radiative temperature measured from polar orbiting satellites to a diurnal cycle ». Diss., The University of Arizona, 1999. http://hdl.handle.net/10150/282883.

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The land surface skin temperature diurnal cycle (LSTD) is very important for the understanding of surface climate and for evaluating climate models. This variable, however, cannot be obtained globally from polar-orbiting satellites because the satellites usually pass a given area twice per day and because their infrared channels cannot observe the surface when the sky is cloudy. In order to more optimally use the satellite data, this research is designed, for the first time, to solve the above two problems by advance use of remote sensing techniques and climate modeling. Specifically, this work is divided into two parts. Part one deals with obtaining the skin temperature diurnal cycle for cloud-free cases. We have developed a "cloud-free algorithm" to combine model results with satellite and surface-based observations, thus interpolating satellite twice-daily observations to the diurnal cycle. Part two studies the cloudy cases. The "cloudy-pixel treatment" presented here is a hybrid technique of "neighboring-pixel" and "surface air temperature" approaches. The whole algorithm has been tested against field experiments and climate model CCM3/BATS in global and single column mode simulations. It shows that this proposed algorithm can obtain skin temperature diurnal cycles with an accuracy of 1-2 K at the monthly pixel level.

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42

Otero, Sonia. « A real-time distributed analysis automation for hurricane surface wind observations ». FIU Digital Commons, 2002. https://digitalcommons.fiu.edu/etd/3466.

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From 1993 until 1999, the Hurricane Research Division of the National Oceanic and Atmospheric Administration (NOAA) produced real-time analyses of surface wind observations to help determine a storm's wind intensity and extent. Limitations of the real-time analysis system included platform and filesystem dependency, lacking data integrity and feasibility for Internet deployment. In 2000, a new system was developed, built upon a Java prototype of a quality control graphical client interface for wind observations and an object-relational database. The objective was to integrate them in a distributed object approach with the legacy code responsible for the actual real-time wind analysis and image product generation. Common Object Request Broker Architecture (CORBA) was evaluated, but Java Remote Method Invocation (AMI) offered important advantages in terms of reuse and deployment. Even more substantial, though, were the efforts towards object-oriented redesign, implementation and testing of the quality control interface and its database performance interaction. As a result, a full-featured application can now be launched from the Web, potentially accessible by tropical cyclone forecast and warning centers worldwide.

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Chartrand, Daniel 1955. « Ventilation by high-frequency body-surface oscillation in rabbits ». Thesis, McGill University, 1989. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=75917.

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Ventilation by high-frequency body-surface oscillation (HFBSO) was studied in normal rabbits. Adequate ventilation and acceptable gas exchange took place during HFBSO from 3 to 15 Hz. The tidal volume required to maintain a normocapnic state was established at each frequency studied. Using catheter-tip micromanometers inserted in the esophagus or the superior vena cava, new techniques to measure high-frequency intrathoracic pressure oscillations were developed. Using a gamma-function to fit the thermodilution curve, a new technique was developed to measure the cardiac output in small animals. No detrimental hemodynamic effect was found during HFBSO used either for normocapnic ventilation or with large pressure oscillations (30 cm H$ sb{ rm 2}$O) in the body chamber. Finally, during normocapnic ventilation by HFBSO in normal rabbits, the mechanical behavior of the respiratory system was characterized using transfer impedances.

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Lu, Jing S. M. Massachusetts Institute of Technology. « Seismic tomography and surface deformation in Krýsuvík, SW Iceland ». Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/87506.

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Thesis: S.M. in Geophysics, Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2013.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 59-62).
The Krýsuvík region of southwestern Iceland is a region of high potential for geothermal energy that is currently experiencing seismic swarm activity and active surface deformation. Understanding the subsurface structure of the area is of great scientific and practical significance. Using permanent and temporary seismic stations deployed in the region, we captured an earthquake swarm from Nov. 2010 to Feb. 2011 clustered around the center of the Krýsuvík volcanic system. We studied the seismicity and Vp, Vs and Vp/Vs ratio in this region by applying double difference tomography. Our tomography result indicates a low velocity zone at a depth of about 6 kin, directly beneath the earthquake swarm. At the same time, our relocation result delineates strike-slip and dip-slip faults above and around this low velocity zone. Brittle-ductile transition is delineated based on the distribution of the earthquakes in this area. In order to understand the relation between the subsurface structure and the surface deformation, we modeled surface deformation using the input parameters constrained from our tomography results. We found that the main deformation is well captured by a pressure source yielding a volume expansion of about 30x 106 m3 at the depth of about 6 km, centered on the low velocity zone detected in tomography. And the secondary deformation could be explained by the normal and the right-lateral slip faults, whose patterns are delineated by the earthquake relocations. The combination of the local stress caused by the expanding source and regional stress that yields a combination of left-lateral shear and extension might have triggered the earthquakes. Based on the low Vp, Vs and possibly high Vp/Vs ratio at depth of ~6 km and its expanding property, the possibilities of supercritical water, H₂O-rich partial melting with magma intrusion are discussed. The results of this thesis provide new insights to understand the seismicity and surface deformation in volcanic zones as well as provided important reference in exploration of new geothermal areas.
by Jing Liu.
S.M. in Geophysics

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Rigel, Adam C. « Modeling sea surface height in the Gulf of Mexico ». Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/114359.

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Thesis: S.B., Massachusetts Institute of Technology, Department of Earth, Atmospheric, and Planetary Sciences, 2008.
Cataloged from PDF version of thesis. "May 9, 2008."
Includes bibliographical references (pages 25-26).
A model was created to form synthetic plots of sea surface height (SSH) from monthly SSH statistics in the Gulf of Mexico generated from satellite laser altimetry data. SSH is a signal of the upper ocean mixed layer heat content and is an input for hurricane intensity models. A significant ocean feature in the Gulf of Mexico is the Loop Current (LC) which sheds warm eddies into the Gulf of Mexico at irregular intervals, which adds to the variability in monthly SSH readings beyond seasonal change. Satellite laser altimetry data was used from October 14th 1992 to May 23rd 2007. The SSH data included an area of the Gulf of Mexico (16°N-30°N latitude, 80°W-100°W longitude) with a resolution of 1/3° by 1/3° on a Mercator grid. Monthly SSH averages, variances, and covariances were created from a total of 763 samples, which allowed for approximately 65 samples per month. Once monthly SSH averages, variances, and covariances were made, synthetic plots were made by using a Karhunen-Loève transform, the Singular Variable Decomposition of the SSH monthly covariance, and random vector composed of random numbers in a Gaussian distribution. Differences in synthetic SSH plots compared to individual SSH observations could vary greatly; the average of all synthetic SSH plot nodes differed by no more than plus or minus 10 cm. The difference between observed and synthetic SSH variance was no more than 400 cm². The large differences occurred in the in the eddy shedding region of the LC. To assess the effectiveness of the model, the synthetic SSH model will need to be used in a hurricane intensity model.
by Adam C. Rigel.
S.B.

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46

Schroeder, Brett. « Surface modification enhanced semiconductor-on-insulator heteroepitaxy / ». Thesis, Connect to this title online ; UW restricted, 2000. http://hdl.handle.net/1773/9808.

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47

GALAL, TAREK. « Interactions ondes electromagnetiques et surfaces rugueuses : applications a la surface cutanee ». Besançon, 1989. http://www.theses.fr/1989BESA2007.

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Solution analytique de la dispersion d'une onde electromagnetique par une surface rugueuse, prenant en compte les parametres locaux de la topographie=une autre technique est developpee basee sur l'utilisation d'elements finis ou de differences finies

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48

Torne, Olaf. « Un problème de dirichlet pour l'opérateur de la surface minimale ». Doctoral thesis, Universite Libre de Bruxelles, 2000. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211784.

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49

Alves, Verdasca José A. « Pattern formation in surface reactions :the role of nonlinear diffusion ». Doctoral thesis, Universite Libre de Bruxelles, 2000. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211803.

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50

Dubois, Patrice. « Signal transduction by the surface antigen receptors of B lymphocytes ». Doctoral thesis, Universite Libre de Bruxelles, 1991. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/213058.

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Thèses sur le sujet « Surface sciences »

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