Geosynthetic tubes filled with water are considered. The tubes can be used in applications to resist rising floodwaters. They can also be used to form breakwaters and protect shores from erosion. This thesis considers single and stacked tubes resting on a rigid and deformable foundation resisting rising hydrostatic headwater. Experiments were carried out to determine the behavior of a three-tube stacked configuration resting on a sand foundation. This study was a continuation of previous work on unstacked tubes. Many tests were performed to determine the deformation and stability of the system. A geosynthetic drain was placed beneath the tubes to prevent piping. The objective was to cause failure of the system in a sliding manner and formulate a hypothesis according to the placement of the drain beneath the tubes. In order to cause a sliding failure, a strapping system was developed to try and prevent the tubes from rolling. A single tube at rest, filled with water but with no external hydrostatic pressure, was considered for analysis first. The tube rested on a rigid foundation and was assumed to be infinitely long. The friction between the tube and the foundation was neglected, and the bending stiffness of the tube was assumed to be negligible. The tube material was assumed to be inextensible. Mathematica was used to solve the system of equations and compute the unknowns. Excel was used to plot the data and observe the behavior of the tubes. An analysis was also performed on a single tube with an apron attached, resting on a rigid foundation. The apron was attached on the rising headwater side to increase stability. The assumptions for the tube at rest were also applied in this analysis. Two cases were derived and analyzed: a case where the internal hydrostatic pressure remains constant, and a case where the cross-sectional area remains constant. For the second case, the internal pressure changes as the floodwater level rises. The results from this study demonstrated that water-filled tubes, stacked or with an apron attached, can be an effective alternative method to sandbags in resisting floodwaters. / Master of Science

Charge transfer at the organic/inorganic semiconductor interfaces lies at the heart of interfacial photochemistry. While decades of research have shaped the current understanding that interfacial charge transfer depends crucially on energetic driving force and electronic coupling, much less is known about the role played by the spin degree of freedom. In particular, it is not clear how spin states evolve during the charge transfer process. With the advent of group 6 transition metal dichalcogenides (TMDC), a class of two-dimensional layered materials which permits the optical generation of spin-polarized electron-hole pairs in the monolayer limit, we now have the opportunity to investigate if charge transfer at an organic/inorganic interface could enable the transfer of spin polarization. Using time-resolved Faraday rotation and transient absorption spectroscopy, it is found in the MoSe₂/H₂Pc and C60/WS₂ heterostructures that the photoinduced hole transfer from MoSe₂ to H₂Pc and electron transfer from WS₂ to C60 results in spin polarization lifetimes one order of magnitude longer than that of a monolayer. In the WS₂/MoSe₂/H₂Pc heterostructure, the addition of a WS₂ monolayer drives the dissociation of electron-hole pairs bound at the MoSe₂/H₂Pc interface and leads to the observation of nanosecond-long spin polarization at room temperature. These findings evidence the photoinduced transfer of spin polarization, a mechanism which could potentially be exploited to enhance the efficiency and selectivity of photochemical reactions involving angular momentum change, and may be generalized to other organic/inorganic interfaces composed of crystalline semiconductors with spin-momentum locking.

Yes / Reverse osmosis (RO) has become a significant method for removing salts and organic compounds from seawater and wastewater in recent decades. Spiral-wound module has been widely used due to a number of special features such as high packing density, premium separation and low operating cost. In this paper, a two-dimensional mathematical model is developed for the transport of dilute aqueous solutions through a spiral-wound RO module and the operational characteristics of the process under steady state conditions are analysed. The model is based on the solution-diffusion model coupled with the concentration polarization mechanism. This model yields a set of Differential and Algebraic Equations (DAEs), which are solved using the gPROMS software. The model is validated using experimental data from the literature for the rejection of dimethylphenol as solute in aqueous solutions. The model is then used to simulate the process under steady state conditions to gain deeper insight of the process.

Face verification is a challenging pattern recognition problem. The face is a biometric that, we as humans, know can be recognised. However, the face is highly deformable and its appearance alters significantly when the pose, illumination or expression changes. These changes in appearance are most notable for texture images, or two-dimensional (2D) data. But the underlying structure of the face, or three dimensional (3D) data, is not changed by pose or illumination variations. Over the past five years methods have been investigated to combine 2D and 3D face data to improve the accuracy and robustness of face verification. Much of this research has examined the fusion of a 2D verification system and a 3D verification system, known as multi-modal classifier score fusion. These verification systems usually compare two feature vectors (two image representations), a and b, using distance or angular-based similarity measures. However, this does not provide the most complete description of the features being compared as the distances describe at best the covariance of the data, or the second order statistics (for instance Mahalanobis based measures). A more complete description would be obtained by describing the distribution of the feature vectors. However, feature distribution modelling is rarely applied to face verification because a large number of observations is required to train the models. This amount of data is usually unavailable and so this research examines two methods for overcoming this data limitation: 1. the use of holistic difference vectors of the face, and 2. by dividing the 3D face into Free-Parts. The permutations of the holistic difference vectors is formed so that more observations are obtained from a set of holistic features. On the other hand, by dividing the face into parts and considering each part separately many observations are obtained from each face image; this approach is referred to as the Free-Parts approach. The extra observations from both these techniques are used to perform holistic feature distribution modelling and Free-Parts feature distribution modelling respectively. It is shown that the feature distribution modelling of these features leads to an improved 3D face verification system and an effective 2D face verification system. Using these two feature distribution techniques classifier score fusion is then examined. This thesis also examines methods for performing classifier fusion score fusion. Classifier score fusion attempts to combine complementary information from multiple classifiers. This complementary information can be obtained in two ways: by using different algorithms (multi-algorithm fusion) to represent the same face data for instance the 2D face data or by capturing the face data with different sensors (multimodal fusion) for instance capturing 2D and 3D face data. Multi-algorithm fusion is approached as combining verification systems that use holistic features and local features (Free-Parts) and multi-modal fusion examines the combination of 2D and 3D face data using all of the investigated techniques. The results of the fusion experiments show that multi-modal fusion leads to a consistent improvement in performance. This is attributed to the fact that the data being fused is collected by two different sensors, a camera and a laser scanner. In deriving the multi-algorithm and multi-modal algorithms a consistent framework for fusion was developed. The consistent fusion framework, developed from the multi-algorithm and multimodal experiments, is used to combine multiple algorithms across multiple modalities. This fusion method, referred to as hybrid fusion, is shown to provide improved performance over either fusion system on its own. The experiments show that the final hybrid face verification system reduces the False Rejection Rate from 8:59% for the best 2D verification system and 4:48% for the best 3D verification system to 0:59% for the hybrid verification system; at a False Acceptance Rate of 0:1%.

L’oncogène v-erbA transforme les progéniteurs érythrocytaires primaires aviaires (T2EC) en bloquantleur engagement d’un programme d’auto-renouvellement vers un programme de différenciation. Unecomparaison trancriptomique de T2EC exprimant soit v-erbA, soit une forme non transformante de verbAa été réalisée par SAGE et RT-qPCR. Seuls quelques uns, mais pas tous les messagers codant lesprotéines ribosomiques sont réprimés. Ces résultats suggèrent que v-erbA pourrait moduler lacomposition des ribosomes et/ou moduler les fonctions extra-ribosomiques de protéines ribosomiquesspécifiques. Ainsi, nous avons décidé d’analyser le taux des protéines ribosomiques associées auxribosomes par 2D-DIGE à partir des ribosomes purifiés. L’analyse statistique effectuée sur 4expériences indépendantes avec des marquages inversées a montré de manière significative que letaux de RPL11 est inférieur dans les T2EC exprimant v-erbA comparé à ceux exprimant la forme nontransformante de v-erbA. Ces données indiquent l’existence de ribosomes dépourvus de RPL11 dansles T2EC sous l’effet de v-erbA. Les résultats des expériences d’immunoprécipitation ont conforté cettehypothèse. L’ensemble des résultats obtenus suggèrent l’implication des protéines ribosomiques, etspécialement celle de RPL11, dans les processus de transformation induite par l’oncogène v-erbA, à lafois au niveau de la traduction, et probablement par sa fonction extra-ribosomique. L’analyse de lafonction biologique de RPL11 a montré qu’une sur-expression de RPL11 dans les T2EC retarderait laprolifération cellulaire. / The v-erbA oncogene transforms chicken erythroid progenitors by blocking their differentiation andpreventing them to exit a state of self-renewal. The transcriptome of primary avian erythroidprogenitors cells (T2EC) expressing either v-erbA or a non-transforming form of v-erbA werecompared by SAGE. Only some, but not all, mRNAs encoding ribosomal proteins were shown to beaffected. These results suggest that v-erbA could modulate the composition of ribosomes and/ormodulate the extraribosomal functions of specific ribosomal proteins. We therefore decided to analyzethe level of ribosomal proteins associated to ribosomes by 2D-DIGE performed on purified ribosomes.A statistical analysis performed on 4 independent flip-flop experiments demonstrated that the level ofRPL11 is significantly lower in T2EC expressing v-erbA as compared to the non-transforming form ofv-erbA. These data suggest the presence of ribosomes without RPL11 in T2EC expressing v-ErbA.Results obtained from immunoprecipitation experiments were strengthened this hypothesis. The set ofthese data evoke the involvement of ribosomal proteins, and specially RPL11, in the v-erbAtransformation process both at the translational level and possibly in its extra-ribosomal function.Overexpression of RPL11 in T2EC showed a decrease of cell proliferation.

Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2005. / The two-dimensional flow-field through the stationary blade row of a radial inflow turbine in a torque converter was analysed by means of a potential flow model and a viscous flow model. The purpose was to compare the accuracy with which the two flow models predict the flow field through the static turbine blade row. The freestream turbulence level necessary to optimise the accuracy of the viscous flow model was also investigated. A first order source-vortex panel method with flat panels was used to apply the potential flow model. A radial inflow freestream was used. It was found that the stator blade row directly upstream of the turbine had to be included in the analysis to direct the flow at the turbine inlet. Even then the panel method did not satisfactorily predict the pressure distribution on a typical blade of the static 2nd turbine blade row. A two-dimensional viscous flow model gave excellent results. Furthermore, the two-dimensional viscous flow model was simple to set up due to the fact that symmetry boundary conditions could be used. This facilitated useful predictions of the salient features of the two-dimensional flow through the middle of the radial turbine blade row.

Aerodynamic analysis is an important area of survivability studies. There is a desire to be able to predict the aerodynamic effects of a given damage scenario on an aircraft wing with minimal wind tunnel testing or computational simulations. Due to the limited nature of previous studies, this has not generally been possible. The original contribution of this thesis is a predictive technique developed to estimate the aerodynamic effects of a simulated battle damage hole on an aircraft wing, resulting from a range of attack directions. This technique was successfully validated against experimental data. Testing under two-dimensional conditions was undertaken on a NASA LS(1)-0417MOD aerofoil at a Reynolds number of 500,000. This project simulates the effect of attack direction by varying the offset between upper and lower surface damage holes in both chordwise and spanwise directions. Damage was modelled using circular holes. Lift, drag and pitching moment coefficients were measured and supplemented with surface flow visualisation and surface pressure measurements. Coefficient increments, defined as the difference between the damage cases and a datum undamaged case were used to quantify the effects of the damage, with the performance qualified in terms of weak and strong jets. Weak jets were found to have little effect on the flow and aerodynamic properties, while strong jets caused significant disruption. The effects increased in magnitude with hole size, incidence and proximity of the upper surface hole to the pressure peak. Spanwise offset on the holes had little effect on the jet strength but introduced asymmetry into the surface flow. This effect was found to be due to the behaviour of the flow within the cavity. Three-dimensional testing was undertaken at a Reynolds number of 1,000,000 on a half wing model in order to investigate any changes in the aerodynamic characteristics of the damage when applied to a more representative aircraft wing. The higher Reynolds number exploited the larger wind tunnel working section and provided a value more representative of typical unmanned aerial vehicles. As the damage was moved towards the tip its effects were lessened and the transition from weak jet to strong jet delayed. Spanwise pressure variation from the tip also introduced asymmetry into the jet s surface flow features. Plotting coefficient increments for all attack directions against the pressure coefficient difference between upper and lower surfaces from an undamaged wing, across the equivalent damage hole region highlighted significant trends, which were used as the basis of a predictive technique for a range of hole sizes and attack directions. The validity of the technique was assessed by predicting a previously untested damage case and comparing it against subsequent wind tunnel tests. The results from this validation proved encouraging.

With magnetic storage devices already achieving storage densities of up to 400 Gigabits per square inch (Gb/in2), the state of the art is rapidly approaching theoretical limits (dictated by thermal stability concerns). Hence, there is an eort in the industry to develop alternative magnetic storage technologies. Two-dimensional magnetic recording (TDMR) is one such candidate technology. In contrast to other technologies(e.g. heat-assisted magnetic recording [1], bit-patterned media [2]) which rely on signicant changes being made to the recording medium, TDMR relies on the use of traditional recording media, while relying on signal processing to make improvements in the recording density. Though advantageous due to the fact that no drastic re-engineering of media is required, there are signicant challenges that need to be addressed in order to make TDMR a viable candidate for next-generation recordingsystems.The main challenges involved in TDMR arise due to (i) the small bit-area, along with an aggressive write/read process, which leads to a large amount of noise, and (ii) the two-dimensional nature of the recording process { so far not encountered in today's systems. Thus, a gamut of 2D signal processing algorithms need be developed for the compensation of errors occurring due to the aggressive write/read processes. In this dissertation, we present some of the work done with regard to the signal processing tasks involved in TDMR. In particular, we describe our work on (i) channel modelling, (ii) detection strategies, and (iii) error-correction coding strategies targetted at TDMR.

A glass couldn't contain water unless it contained H2O-molecules. Likewise, a man couldn't be a bachelor unless he was unmarried. Now, the latter is what we would call a conceptual or analytical truth. It's also what we would call a priori. But it's hardly a conceptual or analytical truth that if a glass contains water, then it contains H2O-molecules. Neither is it a priori. The fact that water is composed of H2O-molecules was an empirical discovery made in the eighteenth century. The fact that all bachelors are unmarried was not. But neither is a logical truth, so how do we explain the difference? Two-dimensional semantics is a framework that promises to shed light on these issues. The main purpose of this thesis is to understand and evaluate this framework in relation to various alternatives, to see whether some version of it can be defended. I argue that it fares better than the alternatives. However, much criticism of two-dimensionalism has focused on its alleged inability to provide a proper semantics for certain epistemic operators, in particular the belief operator and the a priori operator. In response to this criticism, a two-dimensional semantics for belief ascriptions is developed using structured propositions. In connection with this, a number of other issues in the semantics of belief ascriptions are addressed, concerning indexicals, beliefs de se, beliefs de re, and the problem of logical omniscience.

This dissertation focuses on methodology specific to microarray data analyses that organize the data in preliminary steps and proposes a cluster analysis method which improves the interpretability of the cluster results. Cluster analysis of microarray data allows samples with similar gene expression values to be discovered and may serve as a useful diagnostic tool. Since microarray data is inherently noisy, data preprocessing steps including smoothing and filtering are discussed. Comparing the results of different clustering methods is complicated by the arbitrariness of the cluster labels. Methods for re-labeling clusters to assess the agreement between the results of different clustering techniques are proposed. Microarray data involve large numbers of observations and generally present as arrays of light intensity values reflecting the degree of activity of the genes. These measurements are often two dimensional in nature since each is associated with an individual sample (cell line) and gene. The usual hierarchical clustering techniques do not easily adapt to this type of problem. These techniques allow only one dimension of the data to be clustered at a time and lose information due to the collapsing of the data in the opposite dimension. A novel clustering technique based on normal mixture distribution models is developed. This method clusters observations that arise from the same normal distribution and allows the data to be simultaneously clustered in two dimensions. The model is fitted using the Expectation/Maximization (EM) algorithm. For every cluster, the posterior probability that an observation belongs to that cluster is calculated. These probabilities allow the analyst to control the cluster assignments, including the use of overlapping clusters. A user friendly program, 2-DCluster, was written to support these methods. This program was written for Microsoft Windows 2000 and XP systems and supports one and two dimensional clustering. The program and sample applications are available at http://etd.vcu.edu. An electronic copy of this dissertation is available at the same address.