Thesis (B.A.(Hons.))-- University of Adelaide, Dept. of Psychology, 1980.

Thesis (M.S.)--Rochester Institute of Technology, 2008. / Typescript. Includes bibliographical references (leaves 93-96).

Thesis (doctoral)--Rijksuniversiteit te Utrecht. / Description based on print version record.

Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2007. / Dr. J. David Frost, Committee Chair ; Dr. G. Wayne Clough, Committee Co-Chair ; Dr. William F. Marcuson III, Committee Member ; Dr. Paul W. Mayne, Committee Member ; Dr. Susan Burns, Committee Member.

In dieser Doktorarbeit wurde die elektronische Struktur von konventionellen und unkonventionellen Supraleitern untersucht. Das Ziel dieser Arbeit war es, die dHvA Parameter zu berechnen und mit experimentellen Daten zu vergleichen. Mit Hilfe des Bandstrukturprogrammes FPLO, welches auf der DFT basiert, untersuchten wir Diboride (MgB$_2$ und TaB$_2$) und schwere Fermionenverbindungen (CeMIn$_5$ und PuMGa$_5$, M=Co, Rh, und Ir) innerhalb der LSD-Näherung. / In this thesis theoretical study of the electronic structure of conventional and unconventional superconductor compounds was carried out. The goal was to calculate the dHvA parameters in comparison with available experimental data. By means of FPLO band structure code based on DFT within LSDA we investigated diborides (MgB$_2$ and TaB$_2$) and heavy fermion compounds (CeMIn$_5$ and PuMGa$_5$, M=Co, Rh, and Ir).

Les propriétés inattendues des nanoparticules d'or font que le contrôle de leur taille, de leur forme et/ou de leur morphologie devient essentiel pour une application ciblée. Des formes variées de nanoparticules en solution colloïdale ont été synthétisées. L'analyse de ces solutions par spectroscopie UV-Visible montre que les nanoparticules anisotropes ont deux bandes plasmoniques. Aussi, le potentiel zêta mesuré révèle que les solutions sont stables dans les conditions d'étude. La caractérisation par la microscopie électronique en transmission a permis d'observer que leur surface présente différentes orientations cristallographiques. Le dépôt sous potentiel du plomb par voltammétrie cyclique a révélé les sites cristallographiques à la surface de ces nanomatériaux. Ces matériaux présentent des proportions de surface orientée (111), (110) et (100) et de défauts cristallins en accord avec les résultats de microscopie. L'étude électrochimique dans l'électrolyte support montre que la formation des oxydes sur ces nanomatériaux dépend de leur structure. La cinétique de croissance des couches d’oxyde sur les nanobâtonnets d’or dépend fortement du potentiel, du temps de polarisation et de la température. Des différentes formes structurales des nanomatériaux d'or synthétisés et en présence de molécules modèles telles que le glucose et l'acide formique, les nanosphères présentent l'activité la plus forte pour l'oxydation du glucose ; tous les nanomatériaux sont moins actifs pour l'oxydation de l'acide formique. Les analyses par FTIR in situ mettent en évidence la gluconolactone comme intermédiaire de cette réaction et la forte influence de la structure de surface. / Due to the unusual properties of gold nanoparticles, the control of their size, their shape and/or their morphology for a well-targeted application becomes essential. Various shape controlled particles in colloidal solutions were synthesized. The analysis of such solution by UV-visible spectroscopy shows that the anisotropic particles exhibit two surface plasmon resonance bands. In addition, the zeta potential measurements reveal that such solutions are stable in the experimental conditions. It is clearly observed by the transmission electron microscopy characterization of these nanomaterials that their surface has different crystallographic orientations. The under potential deposition (upd) of lead by cyclic voltammetry revealed the surface crystallographic sites which present different ratio of orientated surface (111), (110), (100) and defaults confirming the microscopy results. The cyclic voltammetry in supporting electrolyte shows that the oxides formation on these nanomaterials depends strongly on their structure. On gold nanorods, an extensive study of the kinetic of the oxide layers growth shows that this process is affected by the polarization potential and time as well as temperature. The nanospheres exhibited high activity toward the glucose oxidation, while all the synthesized nanomaterials presented low activity toward the formic acid oxidation. Gluconolactone appears as the main intermediate species during the oxidation of glucose which is a surface structure dependent process.

This research has been performed in the framework of the Virtuhcon project, which intends to virtualize high temperature conversion processes. Coal gasification is one of these processes, which is nowadays considered as a promising technology for the chemical industry. This study is devoted to the coal char physical structure, which is one of the most important parameters influencing coal gasification reaction. First, this study presents the extensive literature review of the char physical structure role during its conversion. Collection of the char structural properties as well as their changes during char conversion are shown and discussed. Literature review is followed by the experimental investigations. Chars prepared from two brown coals (Lusatian and Rhenish) were gasified in a laboratory scale fluidized bed reactor in CO2 at temperatures of 800, 850, 900, and 950 °C and atmospheric pressure. Char samples were gasified completely as well as partially in order to evaluate the reaction kinetics and char structural changes during the reaction, respectively. Complete gasification curves were evaluated by different methods, including application of three gasification models (the Random Pore Model, the Volume Reaction Model, and the Shrinking Reaction Model), instantaneous reaction rate approach as well as the self-developed surface-related reaction rate approach. The results of different approaches were compared. This study also presents a comprehensive methodology to analyze coal char physical structure. The variety of measurement techniques (gas physical adsorption, mercury porosimetry, helium pycnometry, SEM, etc.) were applied to assess structural properties of the char, such as specific surface area, particle density, porosity, pore size and shape, structure morphology, etc. Problems associated with the choice of a proper measurement technique and the comparability of the data delivered by different techniques were discussed. The main objective of the study was to link char structural changes to the char gasification kinetics. The specific task of this thesis was to investigate pore size in relation to their availability for the reaction. As such, specific surface areas of pores of different sizes (from sub-micro to mesopores) were correlated to the instantaneous reaction rates. Both chars exhibit similar trends in their structural changes during gasification, although the absolute values differ, especially with respect to the pores of microscale. Furthermore, structural changes were caused not only by the reaction but also by the influence of the heat treatment, especially at the earlier stages of the reaction. The most reasonable correlation has been achieved between the instantaneous reaction rate and the specific surface area of mesopores. Sub-micro- and micropores did not govern the gasification reaction under given conditions. Finally, kinetic parameters derived from different evaluation methods were reapplied in order to test their ability to predict the experimental data. Each of the method has its advantages and disadvantages as used for the kinetic evaluation. The results of this study represent a substantive base of the experimentally derived data concerning physical structure and morphology of coal char. The findings can be used in numerical and simulation studies for development, validation, and improvement of the models which consider coal particle as a reactive porous solid.

Das Forschungsgebiet der Kuprat- oder Hochtemperatursupraleiter (HTSL) ist bis heute einer der lebendigsten Bereiche der Physik kondensierter Materie. Ein besonderer Stellenwert kommt dem normalleitenden Zustand oberhalb TC zu, dessen Verständnis wesentlich zu einer Theorie der Hochtemperatur-Supraleitung beitragen könnte. Gegenstand dieser Arbeit ist die Untersuchung der Elektronenstruktur von HTSLn der Bi2Sr2CaCu2O8+[delta](Bi2212)-Familie nahe der Fermifläche im normalleitenden Zustand. Die Experimente wurden mittels winkelaufgelöster Photoemissionsspektroskopie (ARPES) durchgeführt, wobei die hohe Auflösung in Energie und Impuls recht genaue Rückschlüsse auf die Spektralfunktion und die Übergangs-Matrixelemente erlaubt. Die wichtigsten experimentellen Ergebnisse sind: 1) Hochaufgelöste ARPES-Fermiflächenkarten von Bi2212 und (Pb,Bi)2212 zeigen folgendes Bild: Die Hauptfermifläche ist lochartig und um die Ecken der Brillouinzone zentriert. Weiterer Bestandteil der Elektronenstruktur ist die Schattenfermifläche. Bei reinem Bi2212 treten außerdem extrinsische Beugungskopien der Fermifläche auf. 2) ARPES-Messungen entlang der -M-Richtung von Bi2212 zeigen eine starke Abhängigkeit von der Anregungsenergie, die auf starken Matrixelement-Effekten beruht. Verschiedene Methoden zur Bestimmung von kF zeigen, dass die Daten konsistent mit einer lochartigen Topologie der Hauptfermifläche sind. Des Weiteren wird die Qualität verschiedener Methoden zur Bestimmung von kF bei starken Matrixelement-Effekten bewertet. 3) Die Hauptfermifläche von (Pb,Bi)2212 behält ihre lochartige Topologie über einen großen Dotierungsbereich nahe optimaler Dotierung. 4) Erste hochaufgelöste ARPES-Messungen des Zirkulardichroismus wurden an (Pb,Bi)2212 durchgeführt. In der verwendeten nicht-chiralen Messanordnung wird ein CDAD (Circular Dichroism in the Angular Distribution of Photoelectrons)-Effekt beobachtet, dessen Asymmetrie antisymmetrisch bezüglich der Zweischicht-aufgespaltenen Zustände ist.

The interaction between fluids and structures, which is an interdisciplinary problem, has gained importance in a wide range of scientific and engineering applications. Thanks to new advances in computer technology, the numerical analysis of multiphysics phenomena has aroused growing interest. Fluid-structure interactions have been numerically and experimentally studied by many researchers and published by several books, papers, and review papers. Hou et al. (2012) [3] have also published a review paper entitled “Numerical methods for fluid-structure interaction”, which provides useful knowledge about different approaches for FSI analysis. The key challenge encountered in any numerical FSI analysis is the coupling between the two independent domains with clear distinctions. For example, a structure domain requires discretizing by a Lagrangian mesh where the mesh is fixed to the mass and follows the mass motion. In fact, the Lagrangian mesh is able to deform and follows an individual structural mass as it moves through space and time. Nonetheless, the fluid mesh remains intact within the space, where the fluid flows as time passes. The numerical approaches with regard to FSI phenomena can be divided into two main categories, namely the monolithic approach and the partitioned approach. In the former, a single system equation for the whole problem is solved simultaneously by a unified algorithm; however, in the latter, the fluid and the structure are discretized with their proper mesh and solved separately by different numerical algorithms. When a fluid flow interacts with a structure, the pressure load arising from the fluid flow is exerted on the structure, followed by deformations, stresses, and strains of the structure. Depending on the resulting deformation and the rate of the variations, a one-way or two-way coupling analysis can be conducted. Fluid-structure interaction (FSI) is characterized by the interaction of some movable or deformable structure with an internal or surrounding fluid flow. In a fluid-structure interaction (FSI), the laws that describe fluid dynamics and structural mechanics are coupled. There is also another classification for FSI problems on the basis of mesh methods: conforming methods and non-conforming methods. In the first method, the interface condition is regarded as a physical boundary (interface boundary) moving during the solution time, which imposes the mesh for the fluid domain to be updated in conformity with the new position for the interface. In contrast, the implementation of the second method eliminates a need for the fluid mesh update on the account of the fact that the interface requirement is enforced by constraints on the system equations instead of the physical boundary motion. In this work, we study numerically and experimentally the fluid-structure interaction comprising a flexible slender shaped structure, free surface flow and potentially interacting rigid structures, categorized in flood protection applications, whereas more emphasis is given to numerical analysis. Objectives of this study are defined in detail as follows: The initial aim is the numerical analysis of the behavior of a down-scale membrane loaded by hydrostatic pressures, where the numerical results have to be validated against available experimental data. A further case which has to be investigated is how the full scale flexible flood barrier behaves when approached and impacted by an accelerated massive flotsam. The numerical model has to be built so as to replicate the same physical phenomenon investigated experimentally. It enables a comparison between the numerical and experimental analyses to be drawn. A more complicated case where the flexible down-scale membrane interacts with a propagated water wave is a further target area to study. Moreover, an experimental investigation is required to validate the numerical results by way of comparison. The ultimate goal is to perform a similitude analysis upon which a correlation between the full-scale prototype and the down-scale model can be formed. The implementation of the similarity laws enables the behavior of the full scale prototype to be quantitatively assessed on the basis of the available data for the down-scale model. In addition, in order to validate the accuracy of the similitude analysis, numerical analyses have to be carried out.:Contents Zusammenfassung I ABSTRACT IV Nomenclature X 1 Introduction 1 1.1 Work overview 2 1.2 Literature review 3 1.2.1 The non-conforming methods 6 1.2.2 The conforming (partitioned) approaches 11 1.2.2.1 Interface data transfer 16 1.2.2.2 Accuracy, stability and efficiency 16 1.2.2.3 Modification of interface conditions: Robin transmission conditions 18 1.3 Concluding remarks 19 2 Methodology-numerical methods for fluid-structure interaction analysis (FSI) 20 2.1 Single FV framework 21 2.1.1 The prism layer mesher 24 2.1.2 Turbulence modeling 24 2.2 Preparation of the standalone Abaqus model 27 2.2.1 Damping by bulk viscosity 28 2.2.2 Coulomb friction damping 29 2.2.3 Rayleigh damping 29 2.2.4 Determination of the Rayleigh damping parameters based on the Chowdhury procedure 29 2.2.5 The frequency response function (FRF) measurement 30 2.2.6 The half-power bandwidth method 31 2.3 Explicit partitioned coupling 33 2.4 Implicit partitioned coupling 39 2.5 Overset mesh 40 2.6 Concluding remarks 42 3 Verification and validation of the structural model 44 3.1 Numerical model setup of the down-scale membrane 44 3.2 Comparing similarity between numerical and experimental results 46 3.2.1 Hypothesis test terminology 46 3.2.2 Curve fitting 47 3.2.3 Similarity measures between two curves 48 3.3 Results (down-scale membrane) 52 3.3.1 Similarity tests for the contact length 54 3.3.2 Similarity tests for the slope 58 3.3.3 Similarity tests for the displacement in Y direction 60 3.4 Concluding remarks 63 4 Numerical model setup of the original membrane for impact analysis 66 4.1 Structure domain 67 4.2 Fluid domain 72 4.2.1 Standard mesh and results 74 4.2.2 Overset mesh 80 4.3 Co-simulation model setup and results 88 4.4 Concluding remarks 96 5 Numerical wave generation 100 5.1 Theoretical estimation of the waves 107 5.2 Numerical wave tank setup 110 5.3 Results 114 5.4 Concluding remarks 119 6 Validity of the model with dynamic pressure 121 6.1 Wave tank 123 6.2 Structure domain 127 6.3 Fluid domain 130 6.4 Co-simulation model setup 136 6.5 Experimental approach 137 6.6 Results 141 6.6.1 Similarity tests for the displacement of the membrane in X direction 156 6.6.2 Similarity tests for the displacement of the membrane in Y direction 160 6.6.3 Similarity tests for the displacement of the membrane in Z direction 164 6.7 Concluding remarks 168 7 Similarity 171 7.1 Motivation 171 7.2 Governing equations 174 7.3 Buckingham Pi theorem 175 7.4 Dimensionless numbers 175 Similitude requirement 177 7.5 Simulation setup 178 7.6 Results 179 7.7 Concluding remarks 191 8 Summary, conclusions and outlook 192 List of figures 199 List of tables 209 References 210