Browsing by Author "Goosen, H A"

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    An efficient parallelization of a real scientific application
    (1995) Post, Elizabeth Anne; Goosen, H A
    In the past decade the cost of computing has come down considerably making high-powered computing more easily affordable. As a result many institutions and organisations now have networks of high-powered workstations. Such networks provide a large, generally untapped, source of computing power which can be used for running large scientific applications which previously could only be run on supercomputers. This dissertation shows that a substantial improvement in performance can be achieved by the parallelization of a real scientific application for a heterogeneous network of Sun and Silicon Graphics workstations connected by an Ethernet network, but that this is affected by a number of factors. These factors include communication delays, load balancing, and the number of slaves used. This dissertation shows that performance can be improved by sending more, shorter messages, and by overlapping communication with computation. Part of this thesis concerns the difficulties involved in the evaluation of parallel performance on a heterogeneous network. This dissertation shows that conventional methods such as speedup and efficiency are not appropriate for evaluating the performance of a heterogeneous system, and that linear speed gives a much more representative indication of the actual performance achieved. We also proposed new concepts of perfect linear speed and linear efficiency, which help to evaluate the improvement in parallel performance on a heterogeneous system.
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    Information visualisation
    (1996) Paverd, Wayne; Goosen, H A
    Information visualisation uses interactive three-dimensional (3D) graphics to create an immersive environment for the exploration of large amounts of data. Unlike scientific visualisation, where the underlying physical process usually takes place in 3D space, information visualisation deals with purely abstract data. Because abstract data often lacks an intuitive visual representation, selecting an appropriate representation of the data becomes a challenge. As a result, the creation of information visualisation involves as much exploration and investigation as the eventual exploration of that data itself. Unless the user of the data is also the creator of the visualisations, the turnaround time can therefore become prohibitive. In our experience, existing visualisation applications often lack the flexibility required to easily create information visualisations. These solutions do not provide sufficiently flexible and powerful means of both visually representing the data, and specifying user-interface interactions with the underlying database. This thesis describes a library of classes that allows the user to easily implement visualisation primitives, with their accompanying interactions. These classes are not individual visualisations but can be combined to form more complex visualisations. Classes for creating various primitive visual representations have been created. In addition to this, a number of auxillary classes have been created that provide the user with the ability to swap between visualisations, scale whole scenes, and use automatic level of detail control. The classes all have built-in interaction methods which allow the user to easily incorporate the forms of interaction that we found the most useful, for example the ability to select a data. item and thereby obtain more information about it, or the ability to allow the user to change the position of certain data items. To demonstrate the effectiveness of the classes we implemented and evaluated a. number of example systems. We found that the result of using the classes was a decrease in development time as well as enabling people with little, or no visualisation experience to create information visualisations.
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    Visualizing the performance of parallel programs
    (1996) Hinz, Peter; Goosen, H A
    The performance analysis of parallel programs is a complex task, particularly if the program has to be efficient over a wide range of parallel machines. We have designed a performance analysis system called Chiron that uses scientific visualization techniques to guide and help the user in performance analysis activities. The aim of Chiron is to give the user full control over what section of the data he/she wants to investigate in detail. Chiron uses interactive three-dimensional graphics techniques to display large amounts of data in a compact and easy to understand/ conceptualize way. The system assists in the tracking of performance bottlenecks by showing data in 10 different views and allowing the user to interact with the data. In this thesis the design and implementation of Chiron are described, and its effectiveness illustrated by means of three case studies.