<p>A new model, referred to as the Rational Dispersion Model is proposed for modeling of dispersive materials in wide wavelength range using the Finite-Difference Time-Domain(FDTD) method. A hardware-accelerated FDTD method combined with the matrix pencil method is proposed to solve both guided and leaky modes. A circuit model based on the complex mode theory is proposed for analysis of large scale structures with non-negligible radiation effects.</p> / Doctor of Philosophy (PhD)

Included in this file is a CD drive titled "Chapter Three: Supporting Information" with a 00:40 second long animation. For best quality, view in VLC, not Quicktime Player. / <p>Groundwater contamination by dense non-aqueous phase liquids (DNAPLs ), such as chlorinated solvents, continues to be a significant environmental problem. When released to the subsurface, either due to improper disposal or accidental release, DNAPLs can form complex source zones whose geometry is largely controlled by the geological heterogeneity of the subsurface. These source zones are composed of disconnected, immobile blobs or ganglia trapped by capillary forces (referred to as DNAPL residual) between high-saturation regions located at permeability interfaces (referred to as DNAPL pools). The slow dissolution of DNAPL pools can result in the contamination of groundwater for time periods on the order of decades to centuries.</p> <p>The common conceptual model used in the investigation of DNAPL-contaminated sites is based primarily on the mass transfer from DNAPL to the surrounding aqueous phase in the saturated zone. However, the presence of a discontinuous gas phase above a DNAPL pool can significantly affect the mass transfer from the pool through repeated, spontaneous expansion and mobilization of the gas phase. This mechanism has not been included in the common conceptual models.</p> <p>The goal of this research was to develop a quantitative understanding of discontinuous gas phase expansion and mobilization above a DNAPL pool. This goal was addressed using a combination of small-scale and intermediate-scale laboratory experiments. Small-scale, no-flow vial experiments were used to measure the expansion of single gas bubbles above DNAPL pools, and provide the basis for the development of an analytical model to assess the effect of expansion by multi-component partitioning on the mass transfer from DNAPL pools. Small-scale flow cell experiments were used to measure spontaneous expansion rates in porous media, and provide visual data concerning the distribution of the gas phase. Small-scale air injection experiments were used to characterize the gas flow. Finally, an intermediate-scale flow cell experiment was used to provide larger-scale data concerning the transient distribution of the gas phase, and measure the effect of spontaneous expansion and mobilization on the aqueous-phase DNAPL constituent concentrations.</p> <p>The combined results of these experiments established a detailed conceptual model for the spontaneous expansion and mobilization of a discontinuous gas phase above a DNAPL pool. In this conceptual model, spontaneous expansion of a discontinuous gas phase above a DNAPL pool occurs due to multi-component partitioning, and depends on the concentrations of both the volatile DNAPL and the other dissolved gases. This expansion is more likely to occur, and will be faster, in shallower systems (i.e. lower hydrostatic pressures) containing coarser media (i.e. lower capillary pressures), more volatile DNAPL, and higher concentrations of other dissolved gases (i.e. higher partial pressures). Mobilization of the expanding gas will occur as discontinuous gas flow in most sands, where the repeated trapping and coalescence of gas clusters can allow rapid, large-scale vertical transport of the gas phase. This discontinuous gas flow can produce macroscopic gas fingers composed of multiple, discrete gas clusters. These macroscopic fingers can reach substantial heights above the pool surface, but the growth occurs predominantly at the pool's leading edge due to the stripping of other dissolved gases. This expansion and mobilization can significantly affect the mass transfer from the DNAPL pool if the gas phase is in direct contact with the pool surface; or if the gas phase is close to the pool surface, covers a large fraction of the pool, and the groundwater flow is sufficiently slow. The partitioning of DNAPL constituent from the mobilized gas phase to the aqueous phase well above the pool surface can also change the spatial distribution of aqueous-phase DNAPL constituent concentrations, increasing them above those that are expected based on theoretical calculations for strictly DNAPL-water systems, even at elevations where the concentrations are expected to be zero. The increased concentrations well above the pool surface can appear as short-duration events in the presence of a sustained gas phase, due to the partitioning of DNAPL constituents from the gas to the aqueous phase during multi-component mass transfer. The results of this research provide the necessary basis to begin incorporating this fundamental mechanism into the conceptual and mathematical models used for DNAPL-related research, the investigation ofDNAPL-contaminated sites, and the design and application of DNAPL remediation technologies.</p> / Thesis / Doctor of Philosophy (PhD)

Between 1845 and 1848, the United States doubled the size of its land holdings in North America, as Texas, Oregon, California, New Mexico, and other western regions were placed under the umbrella of U.S. sovereignty. Echoing John L. O’Sullivan’s famous phrase, historians have deemed these acquisitions “Manifest Destiny,” and have assumed that U.S. expansion – whether for good or ill – was foreordained. Yet this understanding fundamentally fails to take into account the history of the decade prior to 1846, when Americans throughout the continent believed that it was more likely that the United States would not expand beyond its borders. Examining five groups of Americans operating at the nations geographic and/or social margins, this dissertation argues that these groups hoped to achieve sovereignty outside of the United States. Nurtured by Jacksonian rhetoric that celebrated local government and personal ambition, and wary of – and at times running from – a United States mired in depression and uncertainty, these Americans were, in effect, forming their own “breakaway republics.” To validate their goal of self-sovereignty, breakaway republicans looked to the independent Republic of Texas, often referring to Texas to explain their objectives, or looking to Texas as an ally in achieving them. Between 1836 and 1845 – what this dissertation defines as “the Texas Moment” – Texas’ independent existence presupposed a different map of North America, where peoples of the northern, southern, and western borderlands carved out polities for themselves. With Texas in mind, even Americans who did not share the goals of breakaway republicans believed that independent American-led polities on the continent were likely, acceptable, and perhaps even desired. However, to a cabal of Democratic expansionists and James K. Polk in particular, this future was unacceptable. After winning the presidency after an unlikely series of contingencies in 1844, Polk and his allies laid the groundwork for a dramatic expansion of the U.S. state – and thereby a dramatic expansion of U.S. territory. Their actions ended the Texas Moment, thereby subsuming the actions of breakaway republicans and hiding their collective existence from later historians. Ultimately, the events of the mid-1840s were hardly the logical culmination of America’s expansionist destiny, but a profound rupture of the status quo. / History

Water is a scarce resource especially as the water demand is significantly increasing due to the rapid growth of population. Hydrological modelling has gained a lot of attention, as it is the key to predict water availability, optimize the use of water resources and develop risk mitigation schemes. There are still many challenges in hydrological modelling that researchers and designers are trying to solve. These challenges include, but not limited to: i) there is no single robust model that can perform well in all watersheds; ii) model parameters are often associated with uncertainty, which makes the results inconclusive; iii) the required computational power for uncertainty quantification increases with the increase in model complexity; iv) some modelling assumptions to simplify computational complexity, such as parameter independence are, are often not realistic. These challenges make it difficult to provide robust hydrological predictions and/or to quantify the uncertainties within hydrological models in an efficient and accurate way. This study aims to provide more robust hydrological predictions by developing a set of hybrid approaches. Firstly, a hybrid hydrological data-driven (HHDD) model based on the integration of a physically-based hydrological model (HYMOD) and a data-driven model (artificial neural network, ANN) is developed. The HHDD model is capable of improving prediction accuracy and generating interval flow prediction results. Secondly, a hybrid probabilistic forecasting approach is developed by linking the polynomial chaos expansion (PCE) method with ANN. The results indicate that PCE-ANN can be as reliable as but much more efficient than the traditional Monte-Carlo (MC) method for probabilistic flow forecasting. Finally, a hybrid uncertainty quantification approach that can address parameter dependence is developed through the integration of principal component analysis (PCA) with PCE. The results from this dissertation research can provide valuable technical and decision support for hydrological modeling and water resources management under uncertainty. / Thesis / Doctor of Engineering (DEng) / There is a water scarcity problem in the world, so it is vital to have reliable decision support tools for effective water resources management. Researchers and decision-makers rely on hydrological modelling to predict water availability. Hydrological model results are then used for water resources allocation and risk mitigation. Hydrological modelling is not a simple process, as there are different sources of uncertainty associated with it, such as model structure, model parameters, and data. In this study, data-driven techniques are used with process-driven models to develop hybrid uncertainty quantification approaches for hydrological modelling. The overall objectives are: i) to generate more robust probabilistic forecasts; ii) to improve the computational efficiency for uncertainty quantification without compromising accuracy; and, iii) to overcome the limitations of current uncertainty quantification methods, such as parameter interdependency. The developed hybrid approaches can be used by decision-makers in water resources management, as well as risk assessment and mitigation.

The purpose of this study was to investigate whether Kenya's national policies of education are consistent with the principles of nation building and state sovereignty. The investigation involved developing eight multiple regression models. Each model utilized one dependent variable, one independent variable and two control variables. The dependent variables were the average boys and the average girls public primary education gross enrollment ratios for 2000-03, the boys and the girls public primary education completion rates for the class of 2003, and the boys and the girls public primary education gross enrollment ratios for 2003. The independent variables were the public primary education pupil/teacher ratios for 2000 and the public primary education pupil/teacher ratios for 2003. The two control variables were the percentage of the population living in towns in 1999 and the percentage of the population in wage employment in 1999. The only significant results were a negative relationship between public primary education pupil/teacher ratios for 2003 and the girls public primary education completion rates for the class of 2003 and, a positive relationship between the percentage of the population in wage employment in 1999 and the girls public primary education completion rates for the class of 2003. The results suggested that Kenya's national policies of education are not consistent with the principles of nation building and state sovereignty and led to the conclusion that Kenya's public primary education may not be playing the nation-building role that it should play. / Ph. D.

In most applications, the structure components have to be tested under different loading conditions before being placed in operation. A reliable and low cost measuring technique is desirable. However, most currently employed measuring approaches can only provide the structural response at several discrete locations. The accuracy of the measurements varies with the location and orientation of the sensors. Practically, it is not possible to place sensors at all the critical locations for different excitations. Therefore, an approach that derives the full field response using a limited set of measured data is desirable. In contrast to experimental full field measurement techniques, the expansion approach involves analytically expanding the limited measurements to all the degrees of freedom of the structure. Among all the analytical methods, the modal expansion method is computationally efficient and thus more suitable for real time expansion of measured data. In this method, the full-field response is approximated by the linear combination of mode shapes. In previous studies, the modal expansion method is limited by errors from mode aliasing, inaccuracy of the calculated mode shapes and the noise in measurements. In order to overcome these limitations, the modal expansion method is enhanced by mode selection and error compensation in this study. First, the key parameters used in modal expansion method were analyzed using a cantilever beam model and a method for optimal placement of sensors was developed. A mode selection method and error compensation method based on operation modal analysis and adaptive compressed sensing techniques were then developed to reduce the effects of mode aliasing, mode shape inaccuracy and measurement noise. The developed approach was further tested virtually using a numerical model of rotor 67. The numerical model was created using a two-way coupled fluid structure interaction technique. By developing these methods, the enhanced modal expansion approach can provide full field response for structures under different load conditions. Compared to the traditional modal expansion method, it can expand the data with high noise and under general dynamic loading. / Doctor of Philosophy / Accurate knowledge of the strain and stress at critical locations of a given structure is crucial when assessing its integrity. However, currently employed measuring approaches can only provide the structural response at several discrete locations. Practically, it is not possible to place sensors at all the critical locations for different excitations. Therefore, an approach that derives the full field response using a limited set of measured data is desirable. Compared to experimental full field measurement techniques, the expansion approach is focused on analytically expanding the limited measurements to all the degrees of freedom of the structure. Among all the analytical methods, the modal expansion method is computationally efficient and thus more suitable for real-time expansion of measured data. The current modal expansion method is limited by errors from mode aliasing, inaccuracy of the mode shapes, and the noise in measurements. Therefore, an enhanced method is proposed to overcome these shortcomings of the modal expansion. The following objectives are accomplished in this study: 1) Develop a method for optimal placement of sensors for modal expansion; 2) Eliminate the mode aliasing effects by determining the significance of participated modes using operational modal analysis techniques; 3) Compensate for the noise in measurements and computational model by implementing the compressed sensing approach. After accomplishing these goals, the developed approach is able to provide full field response for structures under different load conditions. Compared to the traditional modal expansion method, it can expand the data under dynamic loading; it also shows promise in reducing the effects of noise and errors. The developed approach is numerically tested using fluid-structure interaction model of rotor 67 fan blade.

Coastal forests are facing threats due to rising sea levels, increased storm severity, and land use change. These factors stress trees within coastal ecosystems, potentially predisposing them to attack by insects. In North America, two insect species of concern that pose threats to for coastal forest health are the native baldcypress leafroller (BCLR), Archips goyerana Kruse (Lepidoptera: Tortricidae), and non-native Japanese cedar longhorned beetle (JCLB), Callidiellum rufipenne Motschulsky (Coleoptera: Cerambycidae). Baldcypress leafroller has been reported from Mississippi and Louisiana, with defoliation only reported from the latter where increased flooding has stressed host trees. Through widespread trapping efforts, I found that BCLR occurs north into Arkansas and northeast into Delaware. I conducted environmental niche modeling that indicated that climatically suitable habitat in the United States is primarily in the southeastern United States, but that climatic suitability of the southeastern United States will increase and expands northwards. For JCLB, I found that interceptions of this insect of ports of entry in North America have remained low since the implementation of ISPM-15, and that most interceptions occur on wood packaging materials from the insect’s native range. Environmental niche modeling for JCLB indicated that climatically suitable areas were more prevalent in in the northern hemisphere under current and future climatic scenarios, but that poleward shifts in suitability are likely with ongoing climate change.

The anti-S2 peptides, the stabilizer and destabilizer, were designed to target myosin sub-fragment 2 (S2) in muscle. When the peptides are coupled to a heart-targeting molecule, they can reach the cardiomyocytes and interfere with cardiac muscle contraction. Monoclonal antibodies, MF20 and MF30, are also known to interact with light meromyosin and S2 respectively. The MF30 antibody compared to anti-S2 peptides and the MF20 antibody is used as a control to test the central hypothesis that: Both the anti-S2 peptides and antibodies bind to myosin S2 with high affinity, compete with MyBPC, and possibly interact with titin, in which case the anti-S2 peptides have further impact on myosin helicity and reach the heart with the aid of tannic acid to modulate cardiomyocytes' contraction in live mice. In this research, the effects of anti-S2 peptides and antibodies on myosin S2 were studied at the molecular and tissue levels. The anti-myosin binding mechanism to whole myosin was determined based on total internal reflectance fluorescence spectroscopy (TIRFS), and a modified cuvette was utilized to accommodate this experiment. The binding graphs indicated the cooperative binding of the peptides and antibodies with high affinity to myosin. Anti-myosin peptides and antibodies competition with Myosin Binding Protein C (MyBPC) was revealed through the super-resolution expansion microscopy using wildtype skeletal and cardiac myofibrils, and MyBPC knock-out cardiac myofibril. This new emerging technique depends on using the regular confocal microscope in imaging expanded myofibril after embedding in a swellable hydrogel polymer and digestion. A decrease in the fluorescent intensity at the C-zone was observed in myofibrils labeled with fluorescently labeled anti-S2 peptides or antibodies supporting the competition with MyBPC, which further was confirmed by the absence of this reduction at the C-zone in the knockout MyBPC cardiac tissue. The anti-S2 peptide's ability to reach inside the cardiomyocytes was tested by injecting fluorescently labeled anti-S2 peptides bound to tannic acid in live mice, the destabilizer peptide reached the heart 6X more than the stabilizer peptide. Some of the peptides labeled cardiac arterioles and T-tubules as detected by super-resolution microscopic images, meanwhile some peptides reached inside the cardiomyocytes and labeled some sarcomeres. This dissertation demonstrates the ability of anti-S2 peptides and antibodies in modifying myosin as they bind cooperatively with high affinity to myosin and compete with the regulatory protein MyBPC, in addition to the possible interaction between the stabilizer peptide and titin. Lastly, the peptides succeeded in labeling some cardiac sarcomeres in live mice.

The relationship between the mean square vibrational amplitude of the atoms of a crystalline solid and the thermal expansion of that solid is derived from basic principles, assuming a simple potential energy function between atoms. The functional accuracy of this relationship is proven for several cubic lattice elements and compounds by experimental data reported in the literature. The constants of the relationship are calculated for the materials investigated. / Master of Science

The sintering of (Ca_0.6,Mg_0.4)Zr₄(PO₄)₆ powder (CMZP) synthesized via a new solid-state reaction method was investigated for application as a thermal barrier in next generation internal combustion engines. Specifically, CMZP is being considered as a potential material for the manufacture of exhaust port liners to increase the overall performance of diesel engines. The effects of firing time, firing temperature, and amount of ZnO sintering aid on modulus of rupture (MOR), bulk density, and coefficient of thermal expansion (CTE) were determined for both dry pressed and slip cast samples to optimize the physical properties for this application. For both processing methods, suppressing the formation of secondary interparticle phases (grain boundaries) was found to be the controlling factor for obtaining high strength and positive thermal expansion. For a given ZnO level, increases in firing time and/or temperature resulted in improved density but a degradation in microstructure (undesirable grain growth, formation of a liquid phase, and intra-/trans- granular microcracking), accompanied by a reduction in MOR and negative CTE values. Therefore, optimizing bulk density was determined to be counter-productive for improving strength when ZnO is used as a sintering aid. / Master of Science