Thesis (MScEng)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: After SUNSAT was launched in 1999 and the possibility of developing another micro satellite emerged, areas of possible improvement were identified. Among the suggestions that emerged was the idea of developing an on-board computer for a micro satellite, using one of the new generation low power processors. The processor had to meet guideline specifications derived from the experience gained by researchers and students involved with the SUNSAT project. This thesis covers the process of choosing one of these processors and the subsequent testing of the feasibility of using it in an on-board computer. The feasibility test included comparing the processor's specifications to those required and designing an evaluation board for this processor to test its ease of use and programmability. / AFRIKAANSE OPSOMMING: Nadat SUNSAT in 1999 gelanseer is en die moontlikheid vir die ontwikkeling van In soortgelyke satellite ontstaan het, is areas vir verbetering op bestaande stelsels geidentifiseer. Die idee om In nuwe generasie verwerker met lae kragverbruik as In aanboord rekenaar te gebruik, was een moontlikheid wat ondersoek moes word. Die verwerker moes aan riglyne gemeet, word wat afgelei is uit die ondervinding wat deur navorsers en studente tydens die SUNSAT projek opgedoen is. Die tesis dek die proses wat gevolg is om In verwerker te kies en die daaropvolgende toetsing om die bruikbaarheid van die verwerker as In aanboord rekenaar te bepaal. As deel van die toetsing is die verwerker se spesifikasies teen die verlangde spesifikasies opgeweeg, en In evaluasiebord is ontwikkel om die gemaklikheid van die gebruik en programmering van die verwerker te bepaal.

The problem motivating this study is that database query facilities are not effectively meeting the needs of casual users. A solution to this problem is especially important due to the increasing number of potential casual users. There is considerable controversy revolving around the question of which elements and/or which combination of elements within the casual users' environment are necessary to provide an effective man/machine interface. The purpose of the study is to extend the basic knowledge relating to the effect of using different data models, the effect of cognitive style differences, and the interaction effects of these two independent variables on casual users' performance and confidence in writing database queries. The data models being investigated are the relational, hierarchical, and network models. The cognitive style classifications used are two of the Jungian dimensions, Sensing/Intuition and Thinking/Feeling.

Collaborative Information Retrieval (CIR) is a branch of Computer Supported Cooperative Work (CSCW). CIR is the process by which people search for and retrieve information, working together and using documents as data sources. Currently, computer support for CIR is limited to single user systems. Collaboration takes place either with users working at different times or in different locations. Multi-touch interaction has recently seen a rise in prominence owing to a reduction in the cost of the technology and increased frequency of use. Multi-touch surface computing allows multiple users to interact at once around a shared display. The aim of this research was to investigate how multi-touch interaction techniques could be used to support CIR effectively in a co-located environment. An application architecture for CIR systems that incorporates multi-touch interaction techniques was proposed. A prototype, called Co-IMBRA, was developed based on this architecture that used multi-touch interaction techniques to support CIR. This prototype allows multiple users to retrieve information, using the Internet as a shared information space. Documents are represented as visual objects that can be manipulated on the multi-touch surface, as well as rated, annotated and added to folders. A user study was undertaken to evaluate Co-IMBRA and determine whether the multi-touch interaction techniques effectively supported CIR. Fifteen teams of two users each participated in the user study. High task completion rates and low task times showed that the system was effective and efficient. High levels of user satisfaction were reported in the post-test questionnaires. Participants rated the system as highly useful and several commented that it promoted collaboration and that they enjoyed the test. The successful implementation of Co-IMBRA provides evidence that multi-touch interaction techniques can effectively support CIR. The results of the user evaluation also enabled recommendations for future research to be made.

In recent years, the focus of cartographic research has shifted from the cartographic communication paradigm to the scientific visualization paradigm. With this, there has been a resurgence of cognitive research that is invaluable in guiding the design and evaluation of effective cartographic visualization tools. The design of new tools that allow effective visual exploration of spatial data and data quality information in a resource management setting is critical if decision-makers and policy setters are to make accurate and confident decisions that will have a positive long-term impact on the environment. The research presented in this dissertation integrates the results of previous research in spatial cognition, visualization of spatial information and on-line map use in order to explore the design, development and experimental testing of four interactive visualization tools that can be used to simultaneously explore spatial data and data quality. Two are traditional online tools (side-by-side and sequenced maps) and two are newly developed tools (an interactive "merger" bivariate map and a hybrid o f the merger map and the hypermap). The key research question is: Are interactive visualization tools, such as interactive bivariate maps and hypermaps, more effective for communicating spatial information than less interactive tools such as sequenced maps? A methodology was developed in which subjects used the visualization tools to explore a forest species composition and associated data quality map in order to perform a range of map-use tasks. Tasks focused on an imaginary land-use conflict for a small region of mixed boreal forest in Northern Alberta. Subject responses in terms of performance (accuracy and confidence) and preference are recorded and analyzed. Results show that theory-based, well-designed interactive tools facilitate improved performance across all tasks, but there is an optimal matching between specific tasks and tools. The results are generalized into practical guidelines for software developers. The use of confidence as a measure of map-use effectiveness is verified. In this experimental setting, individual differences (in terms of preference, ability, gender etc.) did not significantly affect performance. / Arts, Faculty of / Geography, Department of / Graduate

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This dissertation presents and evaluates a method of managing spoken dialog interactions with a robust attention to fulfilling the human user’s goals in the presence of speech recognition limitations. Assistive speech-based embodied conversation agents are computer-based entities that interact with humans to help accomplish a certain task or communicate information via spoken input and output. A challenging aspect of this task involves open dialog, where the user is free to converse in an unstructured manner. With this style of input, the machine’s ability to communicate may be hindered by poor reception of utterances, caused by a user’s inadequate command of a language and/or faults in the speech recognition facilities. Since a speech-based input is emphasized, this endeavor involves the fundamental issues associated with natural language processing, automatic speech recognition and dialog system design. Driven by ContextBased Reasoning, the presented dialog manager features a discourse model that implements mixed-initiative conversation with a focus on the user’s assistive needs. The discourse behavior must maintain a sense of generality, where the assistive nature of the system remains constant regardless of its knowledge corpus. The dialog manager was encapsulated into a speech-based embodied conversation agent platform for prototyping and testing purposes. A battery of user trials was performed on this agent to evaluate its performance as a robust, domain-independent, speech-based interaction entity capable of satisfying the needs of its users.

The underlying goal of SUPERvisory Methodology And Notation (SUPERMAN) is to enhance productive operation of human-computer system developers by providing easy-to-use concepts and automated tools for developing high-quality (e.g., human-engineered, cost-effective, easy-to-maintain) target systems. The supervisory concept of the methodology integrates functions of many modeling techniques, and allows complete representation of the designer's conceptualization of a system's operation. The methodology views humans as functional elements of a system in addition to computer elements. Parts of software which implement human-computer interaction are separated from the rest of software. A single, unified system representation is used throughout a system lifecycle. The concepts of the methodology are notationally built into a graphical programming language. The use of this language in developing a system leads to a natural and orderly application of the methodology. / Ph. D. / incomplete_metadata

This thesis presents a data structure for the interactive editing of logic diagrams by means of a storage graphics terminal. It presents an overview of Computer-Aided Design of digital systems, and outlines the requirements of an interactive graphics system. The use of sequential list, hashing, binary tree, and linked list data structures are evaluated, and the data structure is formulated, which includes a combination of linked lists, binary trees, and sequential lists. An illustrative example is presented, along with recommendations for further study. / M.S.

The objective of this thesis is to provide an interactive system for the graphical design and analysis of planar disk cams. The software written for this thesis, the Cam Design System, operates as an add-on application that runs within the CADKEY® graphical environment and inherits all the CADKEY® software functions. It allows the user to specify different follower and motion curve parameters to synthesize a cam, and will analyze the cam for pressure angle flaws. It will also produce output in a numerical data format, as CAD drawings, as a detailed design report, or as NC data. This thesis first discusses what software is already available to perform similar synthesis and analysis, and the extent of documentation of cain design and the use of conjugate geometry theory in literature. Next, it describes how the C-code integrates with the CADKEY® graphical system. The next sections describe all the design theory used in the software, including all the conjugate geometry theory and full descriptions of each of the motion curve characteristics used in the software. The subsequent section describes the software itself and how it is structured, and provides a few examples of designing a cam. The last section sums up the work of this thesis, and provides some recommendations for future work in this area. / Master of Science

This paper is a discussion of the research, design, and implementation of an interactive testing program that was written in VAX-BASIC, and implemented on a VAX-11/780. Computer-assisted test construction and administration are discussed. Free response test items and response selection test items are discussed and implemented as are test, student, and item analysis statistics. The program allows the user to enter, change, delete, or add, question stems. correct answers, and incorrect answers. The program will randomly select questions and appropriate answers from the created test bank. It will either administer and score the test interactively, or produce a printed copy of the test along with an answer key. A statistical package allows the user to produce grade reports and item statistics. The program allows a professor to develop, and administer high quality test. / Master of Science