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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
271

Technologies for enabling versatile information display

Mphepo, Wallen January 2016 (has links)
The thesis work is centered on five objectives. These objectives are among the main factors in the field of electronic information display technologies. They are namely display optical efficiency, crosstalk, resolution, power consumption and switchable 2D/3D capability. The thesis findings and the different levels of success are covered in detail in chapters 4 through chapter 8. They are then summarized in discussion and conclusion chapter using measurable quantities in tabular format. Specifically, with respect to optical efficiency three different solutions were applied. The first raised optical efficiency by 60%. The second solution raised optical efficiency to 90%. The third solution eliminated the need for backlighting altogether as well as remove pixel circuitry from optical light path. With respect to image crosstalk, two solutions were applied. One method reduced crosstalk by 51% while the other method eliminated crosstalk to zero percent in the viewing zones. With respect to resolution two methods were applied. One method increased 3D display resolution by limiting the reduction of the native display resolution by only half regardless of the number of concurrent 3D viewers. The other method increased display resolution 900%. With respect to power consumption two methods were applied. The first method eliminated the need for backlighting and also reduced the number of thin film transistors [TFTs] needed by 60% for the same display resolution. The second method increased display brightness by 60% without increasing power consumption. Finally with respect to 2D/3D switchable display an optical module was designed that successfully enable a conventional 2D display to become a switchable 2D/3D display.
272

Computational modelling of fluid-structure interaction at nano-scale boundaries

Hafezi, Farzaneh January 2014 (has links)
With the emergence of nano-devices and nano-scale research, gaining further understanding of the evolution of drag forces exerted by molecular flows, at low Knudsen numbers (-0.1-0.5), over nano-scaled objects with 20-100 nm size is a realistic expectation. The proposed research examines the fluid-structure interaction at nano-scales from first principles. It has also critically evaluated, and if necessary modified, the assumptions made during the development of a computational model. The research has provided new insights in modelling molecular interaction with continuum as well as molecular walls and calculation procedures for predicting macroscopic properties such as velocity, pressure and drag coefficients. The proposed formulation has been compared with the state of the art formulations as published in recent journals and verified on number numerical and molecular tests as experimental and analytical results are unavailable at this scale. The effect of various geometry configurations (slit pore, inclined and stepped wall) to model the pressure driven molecular flow through confined walls is studied for number of surface roughness and driving force values given by adjusting molecular accelerations. The molecular flow over diamond, circular and square shaped cylinders confined within parallel walls has also been modelled at various input conditions. It is expected that the proposed research will have impact in developing future nanoscale applications, in the field of drug delivery, surface cleaning and protein movement, where adsorption, drag resistance or, in general, understanding of the knowledge of fluid-structure interaction at 50-100nm scale is important. Some of the future research areas resulting from this research have also been identified.
273

An immersed computational framework for multiphase fluid-structure interaction

Yang, Liang January 2015 (has links)
The objective of this thesis is to further extend the application range of immersed computational approaches in the context of hydrodynamics and present a novel general framework for the simulation of fluid-structure interaction problems involving rigid bodies, flexible solids and multiphase flows. The proposed method aims to overcome shortcomings such as the restriction of having to deal with similar density ratios among different phases or the restriction to solve single-phase flows. The new framework will be capable of coping with large density ratios, multiphase flows and will be focussed on hydrodynamic problems. The two main challenges to be addressed are: - the representation, evolution and compatibility of the multiple fluid-solid interface - the proposition of unified framework containing multiphase flows, flexible structures and rigid bodies with possibly large density ratios First, a new variation of the original IBM is presented by rearranging the governing equations which define the behaviour of the multiple physics involved. The formulation is compatibile with the "one-fluid" equation for two phase flows and can deal with large density ratios with the help of an anisotropic Poisson solver. Second, deformable structures and fluid are modelled in a identical manner except for the deviatoric part of the Cauchy stress tensor. The challenging part is the calculation of the deviatoric part the Cauchy stress in the structure, which is expressed as a function of the deformation gradient tensor. The technique followed In this thesis is that original ISP, but re-expressed in terms of the Cauchy stress tensor. Any immersed rigid body is considered as an incompressible non-viscous continuum body with an equivalent internal force field which constrains the velocity field to satisfy the rigid body motion condition. The "rigid body" spatial velocity is evaluated by means of a linear least squares projection of the background fluid velocity, whilst the immersed force field emerges as a result of the linear momentum conversation equation. This formulation is convenient for arbitrary rigid shapes around a fixed point and the most general translation- rotation. A characteristic or indicator function, defined for each interacting continuum phase, evolves passively with the velocity field. Generally, there are two families of algorithms for the description of the interfaces, namely, Eulerian grid based methods (interface tracking). In this thesis, the interface capturing Level Set method is used to capture the fluid-fluid interface, due to its advantages to deal with possible topological changes. In addiction, an interface tracking Lagrangian based meshless technique is used for the fluid-structure interface due to its benefits at the ensuring mass preservation. From the fluid discretisation point of view, the discretisation is based on the standard Marker-and-Cell method in conjunction with a fractional step approach for the pressure/velocity decoupling. The thesis presents a wide range of applications for multiphase flows interacting with a variety of structures (i.e. rigid and deformable) Several numerical examples are presented in order to demonstrate the robustness and applicability of the new methodology.
274

Comparison of two mentoring programs for at-risk black adolescents : a traditional one-to-one mentoring program and a school-to-work transitional program

Frederick, Garnett Noel 05 April 2001 (has links)
The purposes of this study were: (a) to compare the impact of One-to-One (OTO) mentoring interventions administered in the high school setting, and the workplace of the students who participated in the School-to-Work (STW) transitional program, and (b) to identify how the participants perceived their experience in the OTO mentoring program and the STW transitional program. A qualitative approach was used to identify how participants perceived their mentoring experiences with the STW and OTO mentoring programs by utilizing focus groups and content analysis. A quantitative approach was used to compare the statistical differences of outcomes between the STW and OTO mentoring programs, by utilizing descriptive statistics, independent samples Wests, chi- square analyses, and logistic regression. The sample was limited to participants in the STW and OTO mentoring programs resulting in 21 participants for the qualitative approach and 114 participants for the quantitative approach. Results from the qualitative approach indicated that focus group participants in the STW program were satisfied with the program and the relationship with their mentors. They also suggested that the STW program be lengthened to include the entire academic year. Participants from the OTO focus group were dissatisfied with their program due to inadequate mentor involvement. Results from the quantitative approach showed that the increase in school attendance for the STW program’s at-risk Black male youth was statistically significant compared to the OTO program participants; the STW program participants displayed a better outlook for attending college that was statistically significant compared to those in the OTO program; and the OTO program participants displayed a better outlook for permanent employment compared to those in the STW program. Therefore, this study finds that mentoring can contribute to reducing school absences and high school completion in order for at-risk Black adolescents to attend college. It is recommended that the OTO program be restructured to eliminate the disparity that exists regarding the administration of the STW program and the OTO program.
275

A quantitative application of symbolic interactionism to advance directive completion by older adults

Fritschi, Lois P. 07 September 2004 (has links)
This study examined contextual and situational influences on older adults’ decision to complete advance directives by means of a conceptual framework derived from symbolic interactionist theory and a cross-sectional, correlational research design. It was hypothesized that completion of advance directives among older adults would be associated with visiting or participating in the care of a terminally ill or permanently incompetent individual sustained by technology. Using a 53-item questionnaire, computer assisted telephone interviews (CATI) were conducted with 398 community dwelling adults between September and October 2003. Respondents were contacted using random-select dialing from a listed sample of 99% of household telephone numbers in one South Florida census tract. Over 90% of households in this tract include an individual age 65 or older. The results revealed that contrary to most reports in the literature a substantial proportion of older adults (82%) had completed advance directives and that the link between older adults and document completion was mainly through attorneys and not mandated agents, health care professionals. Further, more than one third of older adults reported that religion/spirituality was not an important part of their life, suggesting that the recommended practice of offering religious/spiritual counseling to all those approaching death be reexamined. The hypothesis was not supported (p > .05) and is explained by the situational emphasis on the variables rather than on structural influences. In logistic regression analysis, only increasing age (p = .001) and higher education (p = < .001) were significant but explained only 10% of the variance in document completion. Based on the findings, increased interdisciplinary collaboration is suggested with regard to the advance directive agenda. Since attorneys play a key role in document completion, other professions should seek their expertise and collaboration. In addition, the inclusion of a religious/spiritual preference section in all living wills should be considered as an essential part of a holistic and individually appropriate document. Implications for social work education, practice, and advocacy are discussed as well as suggestions for farther research.
276

Analytical and numerical studies in the theory of tides and storm surges

Flather, Roger Anthony January 1972 (has links)
No description available.
277

Development of a proof of concept for an online automobile configurator / Utveckling av en prototyp för en bilkonfigurator för webben

Nordlander, Gustav January 2018 (has links)
This thesis represents a development from start to a proof of concept for an automobile configurator with 3D visualization. This proof of concept must be independent from other products and should only need a web browser to use. To be able to develop this type of product certain methods must be researched, these include; methods for developing a web based user interface for interaction with a 3D model, different methods for reducing data size of CAD models as well as visualizing the model. As there were two designers working alongside to develop this proof of concept, there was a good opportunity to try different approaches in terms of interface and test them on probable future users. A more conventional approach was preferred by the users and therefore chosen to be developed into a final design that would be for the website. When developing, certain features had to remain unimplemented due to time and resource restraints but the test users were still enthusiastic about such a product if the different aspects were to be polished.
278

Peer relationships, play and language of visually impaired children

Roe, Maria Joao Lopes da Purificacao Windsor January 1999 (has links)
No description available.
279

Students' learning experiences in multigrade and single grade Greek primary schools

Kapsalis, George January 2000 (has links)
No description available.
280

Metaphor in diagrams

Blackwell, Alan Frank January 1998 (has links)
No description available.

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