A large amount of information is contained in textual records, which originate from a variety of sources such as handwritten records and digital media like audio and video files. The information contained in these records is unstructured and to visualise the content of the records is not a trivialtask.In order to visualise information contained in unstructured textual records, the information must be extracted from the records and transformed into a structured format. This research aimed to visualise the coherence of facts contained in textual sources in order to allow the user who make use of the visualisation to make an assumption about the validity of the textual records as a set. For the purpose of the study, it was contemplated that the coherence of facts contained in a document set was indicated by the multiple occurrences of the same fact over several documents in the set. The output of this research is a model that abstracts the process required to transform information contained in unstructured textual records into a structured format and the visual representation of the multiple occurrences of facts in order to support the process of making an assumption about the coherence of facts in the set. This assumption enables the user to make a decision.based on the coherence theory of truth.about the validity of the document set. The modelprovides guidance and practices for performing tasks on similar textualdocument sets containing secondary data. The development of the model was informed by a phased construction of three specific software solution instantiations.namely an initial information extraction, an intermediate visual representation and a final information visualisation instantiation. The final solution instantiation was demonstrated to research participants and was evaluated as well. A pragmatic design science research approach was followed in order to solve the research problem. In conducting the research an adaption of the Peffers et at. (2006) design research process model was followed. The result of the research is a model for the visual representation of the coherence of facts in a textual document set. Expert review of the model is added through a process of peer review and academic scrutiny by means of conference papers and a journal article. It is envisaged that the results of the research can be applied to a number of research fields such as Indigenous Knowledge, History and Law. / School of Computing / M. Sc. (Computing)

There is growing evidence that knowledge co-creation and interactivity during learning interventions aid knowledge acquisition and knowledge transfer. However, learners have mostly been passive consumers and not co-creators of the knowledge visualisation aids created by teachers and instructional designers. As such, knowledge visualisation has been underutilised for allowing learners to construct, demonstrate and share what they have learned. The dearth of appropriate guidelines for the use of knowledge visualisation for teaching and learning is an obstacle to using knowledge visualisation in teaching and learning. This provides a rationale for this study, which aims to investigate usability-based knowledge visualisation guidelines for teaching and learning. The application context is that of Science teaching for high school learners in the Gauteng province of South Africa. Following a design-based research methodology, an artefact of usability-based knowledge visualisation guidelines was created. The artefact was evaluated by testing learners’ conformity to the visualisation guidelines. Qualitative and quantitative data was captured using questionnaires, interviews and observations. The findings indicate that the guidelines considered in this study had various degrees of impact on the visualisations produced by learners. While some made noticeable impact, for others it could be considered negligible. Within the context of high school learning, these results justify the prioritisation of usability-based knowledge visualisation guidelines. Integrating Human Computer Interaction usability principles and knowledge visualisation guidelines to create usability-based knowledge visualisation guidelines provide a novel theoretical contribution upon which scientific knowledge visualisation can be expanded. / School of Computing / M. Sc. (Computing)

This study explores the conceptual relationship between design aesthetics and Aristotelian rhetoric in the context of information visualisation. Aesthetics and rhetorical theory are traditionally studied as separate discourses, but conceptual links between these fields are identified, specifically in terms of communicative goals and strategies. This study therefore compares selected theories on design aesthetics and Aristotelian rhetoric in information visualisation in order to ascertain whether a combined framework may be feasible. Although information visualisation is traditionally practiced from software engineering disciplines, this study frames the practice within the broader field of information design. The democratisation of the field of information visualisation and the emerging practices that emphasise the aesthetic value of visualisations is explored. In order to understand what is meant by the term ‘aesthetic’, a variety of both classical and contemporary views on aesthetics theory is investigated. Even though the term ‘aesthetic’ is not defined, a broad understanding is created by identifying the main conceptual themes in discourse. A specific focus is placed on understanding aesthetics in a design context, since there are many misconceptions about ‘aesthetics’ in this context. The idea that aesthetics relates to the communication of artifacts is explored, which provides a point of departure in linking aesthetics and rhetorical theory. The communicative nature of information visualisations is thus explored in relation to visual rhetorical theory. Aristotle’s three rhetorical appeals, namely logos, pathos and ethos, form the backbone of the visual rhetorical analysis of visualisation artifacts. The aesthetic and rhetorical theories explored throughout the study are compared by applying them to Charles Joseph Minard’s seminal information visualisation of Napoleon’s march to Moscow. This comparative analysis considers the traditional divide between aesthetics and rhetorical theory but identifies sufficient conceptual links between the discourses to suggest that a combined aesthetic-rhetorical framework for information visualisation may indeed be practical. Lastly, the wider implications and potential value of such a combined framework is considered within a broader design context. Copyright / Dissertation (MA)--University of Pretoria, 2012. / Visual Arts / unrestricted

In many everyday tasks it is necessary to compare the performance of the individuals in a population described by two or more criteria, for example comparing products in order to decide which is the best to purchase in terms of price and quality. Other examples are the comparison of universities, countries, the infrastructure in a telecommunications network, and the candidate solutions to a multi- or many-objective problem. In all of these cases, visualising the individuals better allows a decision maker to interpret their relative performance. This thesis explores methods for understanding and visualising multi- and many-criterion populations. Since people cannot generally comprehend more than three spatial dimensions the visualisation of many-criterion populations is a non-trivial task. We address this by generating visualisations based on the dominance relation which defines a structure in the population and we introduce two novel visualisation methods. The first method explicitly illustrates the dominance relationships between individuals as a graph in which individuals are sorted into Pareto shells, and is enhanced using many-criterion ranking methods to produce a finer ordering of individuals. We extend the power index, a method for ranking according to a single criterion, into the many-criterion domain by defining individual quality in terms of tournaments. The second visualisation method uses a new dominance-based distance in conjunction with multi-dimensional scaling, and we show that dominance can be used to identify an intuitive low-dimensional mapping of individuals, placing similar individuals close together. We demonstrate that this method can visualise a population comprising a large number of criteria. Heatmaps are another common method for presenting high-dimensional data, however they suffer from a drawback of being difficult to interpret if dissimilar individuals are placed close to each other. We apply spectral seriation to produce an ordering of individuals and criteria by which the heatmap is arranged, placing similar individuals and criteria close together. A basic version, computing similarity with the Euclidean distance, is demonstrated, before rank-based alternatives are investigated. The procedure is extended to seriate both the parameter and objective spaces of a multi-objective population in two stages. Since this process describes a trade-off, favouring the ordering of individuals in one space or the other, we demonstrate methods that enhance the visualisation by using an evolutionary optimiser to tune the orderings. One way of revealing the structure of a population is by highlighting which individuals are extreme. To this end, we provide three definitions of the “edge” of a multi-criterion mutually non-dominating population. All three of the definitions are in terms of dominance, and we show that one of them can be extended to cope with many-criterion populations. Because they can be difficult to visualise, it is often difficult for a decision maker to comprehend a population consisting of a large number of criteria. We therefore consider criterion selection methods to reduce the dimensionality with a view to preserving the structure of the population as quantified by its rank order. We investigate the efficacy of greedy, hill-climber and evolutionary algorithms and cast the dimension reduction as a multi-objective problem.

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Biological evolution can be described as a unifying concept in biology. A thorough understanding of evolution is thus important to fully understand different areas of biology. However, learning the concepts of evolution has proven difficult, both to students and teachers. During the last decade, the notion of threshold concepts in learning has emerged. Passing the threshold or grasping the threshold concept is a transformative process, thought to be irreversible and has been described as passing a portal to new areas of understanding. Threshold concepts of importance to understanding evolution has been suggested to be time, spatial scale, complexity, randomness and probability. A hypothesis is therefore that facilitating understanding of those threshold concepts also will lead to a greater understanding of evolutionary mechanisms. Visualisations in science communication and learning has gained increased interest and animations as a form of visualisations has proven to facilitate learning in some situations. Since many (threshoid) concepts in evolution are untangible, such as deep time, small scale (micro and sub micro scale) animations could be a way to make those concepts more tangible for learners. In order to explore the potential for animations in learning evolution by making threshold concepts more tangible an interactive animation was designed and tested with upper secondary students in the course Biology 1. The subject of the animation was development of antibiotic resistance in bacteria. Learning effect was measured as differences in pre and post test scores on a selection of previously used concept questions from the literature, the concept inventory of natural selection (CINS). Open ended questions were also used as well as interview sessions, to gain more insight to the eventual effects of the animation. No statiscally significant improvement in the CINS scores could be observed in total, however improvement on a specific question category (biotic potential) could be observed. The number of misconceptions on evolution seemed unaffected after animation. Indications of conceptual conflicts could also be observed after the animation, indicating a potential for conceptual change with future revisions of the animation.

The Semantic Web project has introduced new techniques for managing information. Data can now be organised more efficiently and in such a way that computers can take advantage of the relationships that characterise the given input to present more relevant output. Semantic Web based search engines can quickly educe exactly what is needed to be found and retrieve it while avoiding information overload. Up until now, search engines have interacted with their users by asking them to look for words and phrases. We propose the creation of a new generation Semantic Web search engine that will offer a visual interface for queries and results. To create such an engine, information input must be viewed not merely as keywords, but as specific concepts and objects which are all part of the same universal system. To make the manipulation of the interconnected visual objects simpler and more natural, 3D graphics are utilised, based on the X3D Web standard, allowing users to semantically synthesise their queries faster and in a more logical way, both for them and the computer.

Visualisations of election data produced by the mass media, other organisations and even individuals are becoming increasingly available across a wide variety of platforms and in many different forms. As more data become available digitally and as improvements to computer hardware and software are made, these visualisations have become more ambitious in scope and more user-friendly. Research has shown that visualising data is an extremely powerful method of communicating information to specialists and non-specialists alike. This amounts to a democratisation of access to political and electoral data. To some extent political science lags behind the progress that has been made in the field of data visualisation. Much of the academic output remains committed to the paper format and much of the data presentation is in the form of simple text and tables. In the digital and information age there is a danger that political science will fall behind. This thesis reports on a number of case studies where efforts were made to visualise election data in order to clarify its structure and to present its meaning. The first case study demonstrates the value of data visualisation to the research process itself, facilitating the understanding of effects produced by different ways of estimating missing data. A second study sought to use visualisation to explain complex aspects of voting systems to the wider public. Three further case studies demonstrate the value of collaboration between political scientists and others possessing a range of skills embracing data management, software engineering, broadcasting and graphic design. These studies also demonstrate some of the problems that are encountered when trying to distil complex data into a form that can be easily viewed and interpreted by non-expert users. More importantly, these studies suggest that when the skills balance is correct then visualisation is both viable and necessary for communicating information on elections.

Boiling in microchannels is a very efficient mode of heat transfer with high heat and mass transfer coefficients achieved. Less pumping power is required for two-phase flows than for single-phase liquid flows to achieve a given heat removal. Applications include electronics cooling such as cooling microchips in laptop computers, and process intensification with compact evaporators and heat exchangers. Evaporation of the liquid meniscus is the main contributor to the high heat fluxes achieved due to phase change at thin liquid films in a microchannel. The microscale hydrodynamic motion at the meniscus and the flow boiling heat transfer mechanisms in microchannels are not fully understood and are very different from those in macroscale flows. Flow instability phenomena are noted as the bubble diameter approaches the channel diameter. These instabilities need to be well understood and predicted due to their adverse effects on the heat transfer. A fundamental approach to the study of two-phase flow boiling in microchannels has been carried out. Simultaneous visualisation and hydrodynamic measurements were carried out investigating flow boiling instabilities in microchannels using two different working fluids (n-Pentane and FC-72). Rectangular, borosilicate microchannels of hydraulic diameter range 700-800 μm were used. The novel heating method, via electrical resistance through a transparent, metallic deposit on the microchannel walls, has enabled simultaneous heating and visualisation to be achieved. Images and video sequences have been recorded with both a high-speed camera and an IR camera. Bubble dynamics, bubble confinement and elongated bubble growth have been shown and correlated to the temporal pressure fluctuations. Both periodic and nonperiodic instabilities have been observed during flow boiling in the microchannel. Analysis of the IR images in conjunction with pressure drop readings, have allowed the correlation of the microchannel pressure drop to the wall temperature profile, during flow instabilities. Bubble size is an important parameter when understanding boiling characteristics and the dynamic bubble phenomena. In this thesis it has been demonstrated that the flow passage geometry and microchannel confinement effects have a significant impact on boiling, bubble generation and bubble growth during flow boiling in microchannels.