The volume of poetry Kleur kom nooit alleen nie (Colour never comes on its own) by Antjie Krog, is analysed extensively in this thesis. The main focus of the study is the way in which metaphors associated with boundaries, bordering, transgression and the crossing of boundaries are used to represent the struggle to come to terms with a traumatic past and to rethink new possibilities of co-existence in the future. In the poems the boundaries of the word, the text and the genre of poetry, as well as geographical and political boundaries and the boundaries of gender, especially the boundaries instituted by the patriarchal order, are challenged. The narration of alternative histories to supplement and correct documented history may also be considered as a boundary-crossing activity. Although colour is the most obvious metaphor of the divisions between people and is indeed used as the central metaphor throughout the volume, many other, sometimes more subtle examples of boundaries and bordering are explored and developed. There is for instance a strong focus on the psychological complexity of creativity and of writing poetry. The poet's withdrawal to a liminal zone which incorporates the almost spiritual dimension of her creative activities clearly forms a kind of leitmotiv in the collection. The text clearly suggests that the artist as a liminal figure achieves an enhanced ability to understand the forces at work in a community. Sharing the results of this insight from the liminal zone with the community implies that the artist can stimulate innovative processes which will obliterate boundaries and enable people to co-exist peacefully. Although the crossing of borders in most cases result in being wounded, there are also the possibilities of recovery and healing. The resultant scars are often regarded as strong identity-shaping features in people. Krog argues that language plays a decisive role in processes of reconciliation and that the text itself becomes a threshold area where different discourses interact and cross-fertilise one another. The structure of the thesis reflects the theoretical approach and is an attempt to present a balanced discussion of the aesthetic and the ideological aspects of Kleur kom nooit alleen nie as a poetic text. Appropriate theories are implemented to do justice to both the aesthetic qualities and the ideological undercurrents of single poems as well as the volume as such. Two discourses are therefore superimposed in order to present an adequate reading of this polyphonic and ambivalent text. 'The exploration of the varied manifestations of the boundary forms a continuous thematic line throughout the thesis but related themes such as identity, liminality and hybridity are also incorporated. On account of the postmodernistic nature of the text, the basic theoretical framework is that of literary postmodernism, with narrativity of the text, intertextuality, post-colonialism and feminism as its most significant manifestations. / Thesis (Ph.D. (Afrikaans and Dutch))--North-West University, Potchefstroom Campus, 2007.

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The solution of convection-diffusion problems is a challenging task for numerical methods because of the nature of the governing equation, which includes a non-dissipative component and a dissipative component. Once the convection-diffusion equation is discretised, it is usual to observe oscillations in the computed solution regardless of whether these might be expected in the original physical situation. Mostly these oscillations are the result of numerical instability. This thesis centres on this fundamental difficulty: the numerical stability of finite difference discretisation of a convection-diffusion equation. The existence of an exact evolution operator for the constant coefficient convection diffusion problem is the framework we use to derive new finite difference schemes in one and two dimensions and also, when a high-order scheme is considered, to derive numerical boundary conditions. The influence of numerical boundary conditions on the stability of a general scheme is one of the main themes. The stability analysis is done mostly by using the von Neumann method and the matrix method. The Godunov-Ryabenkii theory is also applied to the one dimensional case. In two dimensions we deduce different forms of second-order (Lax-Wendroff) schemes and third-order (Quickest) schemes. We apply some of those schemes to a Navier-Stokes problem by running experiments to illustrate the practical stability region, showing how results from a simpler case presented in previous chapters carry over to the more complex case.

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Implementation of the ultrasonic second harmonic generation has typically been restricted to simple setups such as through-transmission or Rayleigh surface waves. Recent research has evaluated the second harmonic generation in P- and SV- waves reflected from a stress-free surface to enable the single-sided interrogation of a specimen. This research considers the second harmonic generation in an aluminum specimen, which is analytically evaluated using an approach based on the perturbation method. Here, the model is chosen to mimic an experimental setup where a longitudinal wave is generated at an oblique angle and the reflected wave is detected using a set of wedge transducers. Due to mode conversion at the interface of the wedge and the specimen, it is necessary to evaluate longitudinal and shear waves, determining all second harmonic waves generated in the bulk and at the stressfree boundary. The theoretically developed model is then implemented in a commercial finite element code, COMSOL, using increasing fundamental wave amplitudes for different values of third order elastic constants. The results of this computational model verify the analytical approach and the proposed measurement setup, taking into account assumptions and approximations of the solution procedure. Furthermore, the computational model is used to draw important conclusions relevant to the experimental setup, including the need to avoid evolving surface waves and interactions with diffracted waves. These numerical results are used to develop a recommendation for the measurement position and incident angle. Finally, the nonlinearity of two different aluminum specimens is measured with the suggested measurement setup and the results confirm the feasibility of the single-sided determination of the acoustic nonlinearity using reflected bulk waves.

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Conditional sampling techniques were used to analyze airbourne carbon dioxide and water vapour flux traces recorded during the FIFE experiment. Two analysis methods based on quadrant analysis were used to isolate and examine extreme contributions to estimates of the mean flux. The first method was a graphical analysis based on 'hyperbolic holes'. This method was used to attain the result that 80% of the flux-fraction is carried by 20% of the time-fraction. The second method, based on quadrant analysis, permitted the distinction of physical structures which are thought to represent the signatures of turbulent flux structures such as eddies or thermals. Overall results indicate that mean flux estimates over the FIFE site are dominated by a very few intermittent extreme events.

This thesis describes the development and assessment of an undergraduate wind tunnel test engineering course utilizing the 7ft by 10ft Oran W. Nicks Low Speed Wind Tunnel (LSWT). Only 5 other universities in the United States have a wind tunnel of similar size and none have an undergraduate wind tunnel test engineering course built around it. Many universities use smaller wind tunnels for laboratory instruction, but these experiments are meant to only demonstrate basic concepts. Students go beyond conceptual learning in this wind tunnel test engineering course and conduct real-world experiments in the LSWT. This course puts knowledge into practice and further prepares students whether continuing on to graduate school or industry. Course content mainly originates from the chapters in Low Speed Wind Tunnel Testing by Barlow, Rae, and Pope. This is the most comprehensive book that addresses the specific requirements of large scale, low speed wind tunnel testing. It is not a textbook for novices. The three experiments used in the course are modeled on actual experiments that were performed at the LSWT. They are exactly what a commercial entity would want performed although the time scale is drastically reduced because of class requirements. Students complete the course with a working knowledge of the requirements of large scale, low speed wind tunnel tests because they have successfully performed real-world tests and have performed data reduction that is needed for high-quality industrial tests.

The handling of topological aspects in boundary value problems of engineering electromagnetics is often considered to be an engineer's art and not a science. This thesis is an attempt to show that the opposite is true. Through the use of differential forms and rudimentary concepts from homology theory a paradigm variational boundary value problem is formulated and investigated. It is seen that reasoning in terms of the Tonti diagram for this problem may lead to false conclusions if cohomology groups are ignored. As a prelude to this investigation, a suitable orthogonal decomposition of differential forms is derived and the roles played by the long exact homology sequence and topological duality theorems for compact orientable manifolds with boundary are considered in detail.