The use of accelerator technology, particularly Graphics Processing Units (GPUs), for scientific computing has increased greatly over the last decade. While this technology allows larger and more complicated problems to be solved faster than before it also presents another opportunity: the real-time and interactive solution of problems. This work aims to investigate the progress that GPU technology has made towards allowing fluid-structure interaction (FSI) problems to be solved in real-time, and to facilitate user interaction with such a solver. A mesoscopic scale fluid flow solver is implemented on third generation nVidia ‘Kepler’ GPUs in two and three dimensions, and its performance studied and compared with existing literature. Following careful optimisation the solvers are found to be at least as efficient as existing work, reaching peak efficiencies of 93% compared with theoretical values. These solvers are then coupled with a novel immersed boundary method, allowing boundaries defined at arbitrary coordinates to interact with the structured fluid domain through a set of singular forces. The limiting factor of the performance of this method is found to be the integration of forces and velocities over the fluid and boundaries; the arbitrary location of boundary markers makes the memory accesses during these integrations largely random, leading to poor utilisation of the available memory bandwidth. In sample cases, the efficiency of the method is found to be as low as 2.7%, although in most scenarios this inefficiency is masked by the fact that the time taken to evolve the fluid flow dominates the overall execution time of the solver. Finally, techniques to visualise the fluid flow in-situ are implemented, and used to allow user interaction with the solvers. Initially this is achieved via keyboard and mouse to control the fluid properties and create boundaries within the fluid, and later by using an image based depth sensor to import real world geometry into the fluid. The work concludes that, for 2D problems, real-time interactive FSI solvers can be implemented on a single laptop-based GPU. In 3D the memory (both size and bandwidth) of the GPU limits the solver to relatively simple cases. Recommendations for future work to allow larger and more complicated test cases to be solved in real-time are then made to complete the work.

Flat plate turbulent boundary layers disturbed by periodic moving wakes have been observed in an experimental rig mounted in a low speed wind tunnel. The wakes are produced periodically by cylinders traversing in front of the leading edge of a flat plate on which the boundary layers are measured. This is to simulate the unsteady flow pattern generated by upstream blades on the downstream blade boundary layer in an axial flow turbomachine. Both the time-averaged and ensemble-averaged data are taken from the free stream and boundary layer at different flow conditions. Free stream steady and unsteady wakes are compared and found to be similar to each other. The wake disturbance in the free stream is a function of time and distance from the cylinder. The periodic disturbance in the inner half of the boundary layer lags behind that in the free stream. This phase lag is due to the lower convection velocity near the solid surface. Similar to a steady wake, the velocity defect of an unsteady wake is higher in boundary layer than in free stream. This results in the maximum velocity defect amplitude in the inner half of the boundary layer. Phase lag and amplitude ratio profiles of the boundary layers are plotted and found to be similar to data obtained from axial flow turbomachines. Phase-averaged velocity and turbulence intensity profiles at different phase angles between two successive wakes are shown in a series of transparencies. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

The velocity profile shape and boundary layer thickness of an equilibrium boundary layer grown over a long fetch of roughness are closely matched with those of a boundary layer artificially thickened using spires (by adjusting the shape and height of the spires). Other turbulent characteristics of these two wind tunnel simula tions of the atmospheric wind are then compared. At the same time, more information on rough wall boundary layers is obtained to allow for a rational choice of the shape and spacing of roughness elements required to produce a particular simulation of the full scale boundary layer. A technique for calculating the shape of boundary layers in exact equilibrium with the roughness beneath, using a data correlation for the wall stress associated with very rough boundaries and a semi-empirical calculation method, is examined experimentally. Wall shear stress, measured directly from a drag plate, i combined with boundary layer integral properties to show that the shear stress formula is reasonably accurate and that the boundary layer grown over a long fetch of roughness is close to equilibrium after passing over a streamwise distance equal to about 350 times the roughness element height. The boundary layer quickly generated using spires proved to be a fair approximation to that grown over a long fetch of roughness, but did not accurately represent the longitudinal turbulence intensity of the full scale atmospheric wind or the naturally grown boundary layer. The boundary layer produced here by spires showed little change in gross characteristics after travelling about eight spire heights downstream of the spires. A distance of six or seven such heights has been advised by other workers in the past. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

Boundary Bay is a novel that explores important areas of investigation linked to education. These fields of inquiry include: literary study and the teaching of literature, aesthetics and artistic production. The novel also investigates the nature of teachers' lives in school and university settings, the nature of institutional education, societal issues affecting intellectual and creative life, the roles of the woman poet and teacher, the social structures and conventions of marriage and contemporary women, the conflicts and paradoxes of motherhood, the issues of teen suicide and homosexuality, and the transformative power of literature and artistic forms of seeing the world. As an example of arts-based qualitative research, the "art of fiction" is envisioned as an extension of human experience. The novel or literary narrative as a viable mode of representation for research is envisioned in light of the perception that ideas can be reflectively addressed through the arts in order to enlarge human understandings. Boundary Bay explores the vital roles literary fictions play in our everyday lives and in educational processes. Fictions are not the unreal side of reality or the opposite of reality: they are conditions that enable the production of possible worlds. In this sense, fiction can become a premise for epistemological positionings. The writing of Boundary Bay is informed by narratives of beginning secondary school teachers as well as the narratives of Ph.D. candidates and university educators. Boundary Bay is a novel that forms a response to the debate at the 1996 Annual American Educational Researcher's Association Meeting (AERA) between Elliot Eisner and Howard Gardner recorded in "Should a Novel Count as a Dissertation in Education?" (Saks, 1996; Donmoyer, 1996). The debate between Eisner and Gardner continued as Boundary Bay was presented at a symposium titled "Shaking the Ivory Tower: Writing, Advising and Critiquing the Postmodern Dissertation" at AERA 1999 in Montreal. The manuscript of poetry interwoven through Boundary Bay was short-listed for the 1998 CBC Canada Council Literary Awards. Boundary Bay was a semifinalist for the 1999 Robertson Davies Prize for fiction. / Education, Faculty of / Language and Literacy Education (LLED), Department of / Graduate

A área de recuperação de informação baseada em conteúdo visual vem ganhando importância graças ao volume de material visual existente (imagens e vídeo digitais), compartilhado e distribuído principalmente via Internet, e à capacidade de processamento alcançada pelos computadores pessoais na última década. Novas formas de consumo, manipulação e exploração de vídeo digital podem ser criadas através da organização e indexação apropriada desse material. A delimitação de tomadas fornece uma base para a abstração e estruturação de vídeo, agregando quadros contíguos em seqüências de mesmo contexto, isto é, trechos com unidade em termos de tempo e espaço. Nesta dissertação são apresentados os conceitos básicos de delimitação de tomadas e métodos tradicionais utilizados nesse tipo de segmentação, bem como vários resultados experimentais obtidos a partir de seqüências reais de TV. É analisada a distribuição das diferenças entre quadros sucessivos, calculada através de seus histogramas, na tentativa de caracterizar as transições entre tomadas e obter melhores parâmetros para a segmentação. Obtêm-se experimentalmente mais evidências que comprovam a superioridade da medida de intersecção de histogramas sobre outras medidas. A principal contribuição do trabalho consiste no desenvolvimento de um algoritmo baseado no método twin-comparison, que apresenta melhor desempenho que o método original na detecção dos limites de tomadas por utilizar análise local da variação visual entre os quadros do vídeo. / Visual content based information retrieval is an area of increasing importance due to the large volume of available material (digital images and videos), shared and distributed mainly by the internet, and the processing power achieved by personal computer in the last ten years. New ways to consume digital video and to manipulate and explore its visual information can be made by appropriately organizing and indexing this material. The shot boundary detection is a fundamental tool to video abstraction and structuring, combining near frames into sequences with similar context, segments with space and time unity. This work presents the basic concepts about shot boundary detection, traditional methods used and several experimental results obtained from a real TV data set. The distribution of differences of neighboring frames, calculated from histogram comparison, is used to define the transitions between frames and to obtain better parameters for segmentation. Our experimental results show the superiority of the histogram intersection method over other measures. Our main contribution is the development of a new algorithm based on the twin-comparison method, extended with local analysis of visual content variation between video frames. This algorithm was tested over hours of TV data, and performs better than the original method.

The set of transverse homoclinic intersections for a saddle-focus equilibrium in the planar equilateral restricted four body problem admits certain simple homoclinic orbits which form the skeleton of the complete homoclinic intersection, or homoclinic web. In this thesis, the planar restricted four body problem is viewed as an invariant subsystem of the spatial problem, and the influence of this planar homoclinic skeleton on the spatial dynamics is studied from a numerical point of view. Starting from the vertical Lyapunov families emanating from saddle focus equilibria, we compute the stable/unstable manifolds of these spatial periodic orbits and look for intersections between these manifolds near the fundamental planar homoclinics. In this way, we are able to continue all of the basic planar homoclinic motions into the spatial problem as homoclinics for appropriate vertical Lyapunov orbits which, by the Smale Tangle theorem, suggest the existence of chaotic motions in the spatial problem. While the saddle-focus equilibrium solutions in the planar problems occur only at a discrete set of energy levels, the cycle-to-cycle homoclinics in the spatial problem are robust with respect to small changes in energy. The method uses high order Fourier-Taylor and Chebyshev series approximations in conjunction with the parameterization method, a general functional analytic framework for invariant manifolds. Tools that admit a natural notion of a-posteriori error analysis. Finally, we develop and implement a validation algorithm which we later use to obtain Theorems confirming the existence of homoclinic dynamics. This approach, known as the Radii polynomial, is a contraction mapping argument which can be applied to both the parameterized manifold and the Chebyshev arcs. When the Theorem applies, it guarantees the existence of a true solution near the approximation and it provides an upper bound on the C0 norm of the truncation error. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection

Parasitic friction and material wear exist in all moving parts, causing about 20% in global energy loss annually. Machinery startup accounts for a major portion of this loss. This issue involves a boundary lubrication problem, where rubbing surfaces are inadequately covered by lubricating oils. Lubricating oil fluids rely on tribochemical reactions to establish metalorganic tribofilms that protect the contacting surfaces. The improved oil lubrication mechanism can ensure smooth operation, improving efficiency, and extending the mechanical component lifetime. In this thesis, we study tribochemical reactions resulting from various fuel and oil blends. The interactions among blended additives are given particular attention. Lubrication phenomena are simulated using a ball-on-disk linear reciprocation configuration in a standardized tribological test rig, Optimol SRV5. The tribofilm growth patterns are investigated by measuring friction and electrical contact resistance (ECR), followed by a detailed surface analysis. The proposed lubrication mechanisms are verified with experimental and numerical simulation results. Fuel lubrication studies are conducted by investigating a) lubricity loss upon the addition of multiple oxygenated compounds, b) accelerated material wear rates observed in dieselethanol fuel blends, and c) enhanced lubrication performances with carbon-based nanofluid fuels. Lubricity loss is found to correlate with: ● Extended induction periods for ECR rises, ● Reduced average electrical contact resistance values, and ● Inhibitions of protective frictional species formations (e.g., iron oxides and graphite). The developed tribochemical reaction model advances the design of friction and extremepressure modifiers using tribo-active nanomaterials. For instance, adding carbon-based nanomaterials to fuels enhances lubrication performance by serving as tribo-active materials to accelerate tribofilm formation and by replenishing damaged surfaces. In engine oil systems, we demonstrated that the lubrication performance could be enhanced by formulating TiO2 nanoparticles modified by gallic acid esters, and polyether-based co(ter)polymers. Based on the tribochemical reaction mechanisms found in this study, we propose more designs of functionalized nanomaterials for advanced lubricant applications in future work.

Outdoor green spaces are necessary for cognitive development. Many mentally challenged children in South Africa lack proper treatment and access to green spaces, as well as basic social interaction. This dissertation investigates why play in outdoor spaces is beneficial and how this can be achieved through the basis of a playscape focusing on development and therapy for mentally challenged and abled-bodied children. The design solution also aims to uplift the community and create safe spaces. The main research question asks how a playscape can transform the segregated, derelict areas in Westbury into spaces that encourage child development. The hypothesis states that activity-orientated playground design that recognizes the abilities of mentally challenged and abled-bodied children, and provokes imagination, can create platforms that remove social boundaries and aid in development. Furthermore, naturalistic playground design can aid in solving the issue of boundary within Westbury, while effectively defining open space and creating a sense of place. In order to test the hypothesis, pragmatic requirements for child development were obtained through a literature review and by conducting interviews with therapists dealing with mentally challenged children. Case studies were consulted to understand the application in design. In conclusion, it is confirmed that naturalistic, activity-orientated playground design can create platforms that remove social boundaries and aid in development and therapy. By using archetypical landscape elements that provoke the imagination, a multifaceted playscape can be created. This dissertation in its design application demonstrates that it is possible to use boundary to create safer, integrated spaces, while effectively defining an open space. By this example a playscape and its surrounding spaces can offer platforms for economic, social, communal and environmental upliftment within Westbury. / Mini Dissertation ML(Prof)--University of Pretoria,2018. / Architecture / ML(Prof) / Unrestricted

This study explored 6 high school student’s experiences of setting sexual boundaries. The significance of this study expands the findings and contributes to the existing literature on sexual learning by adolescents setting sexual boundaries. Qualitative methodology, narrative style semi-structured interviews and thematic analysis were used in this study. Research findings point out that youths face significant challenges when setting sexual boundaries, such as, dealing with negative responses, having to maintain boundaries for an extended time, and managing emotional distress after consent is provided, but not followed by, a positive sexual experience. Implications for future research would include an exploration of this research question with a larger and more diverse population. The goal would be to develop findings that could be generalized with a larger population. Further, the goal would be to engage in an increased dialog of sex-education for youths. The important areas to explore would include experiences of setting sexual boundaries, support a healthy integration of the meanings that are associated with these experiences, and to enhance strength-based practices of setting healthy sexual boundaries. / Graduate

Boundary integral equation techniques are useful in thenumerical simulation of scattering problems for wave equations.Their advantage over methods based on partial di.erentialequations comes from the lack of phase errors in the wavepropagation and from the fact that only the boundary of thescattering object needs to be discretized. Boundary integraltechniques are often applied in frequency domain but recentlyseveral time domain integral equation methods are beingdeveloped. We study time domain integral equation methods for thescalar wave equation with a Galerkin discretization of twodi.erent integral formulations for a Dirichlet scatterer. The.rst method uses the Kirchho. formula for the solution of thescalar wave equation. The method is prone to get unstable modesand the method is stabilized using an averaging .lter on thesolution. The second method uses the integral formulations forthe Helmholtz equation in frequency domain, and this method isstable. The Galerkin formulation for a Neumann scattererarising from Helmholtz equation is implemented, but isunstable. In the discretizations, integrals are evaluated overtriangles, sectors, segments and circles. Integrals areevaluated analytically and in some cases numerically. Singularintegrands are made .nite, using the Du.y transform. The Galerkin discretizations uses constant basis functionsin time and nodal linear elements in space. Numericalcomputations verify that the Dirichlet methods are stable, .rstorder accurate in time and second order accurate in space.Tests are performed with a point source illuminating a plateand a plane wave illuminating a sphere. We investigate the On Surface Radiation Condition, which canbe used as a medium to high frequency approximation of theKirchho. formula, for both Dirichlet and Neumann scatterers.Numerical computations are done for a Dirichlet scatterer. / NR 20140805