ETD Collection

Permanent URI for this collectionhttps://wiredspace.wits.ac.za/handle/10539/104


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Now showing 1 - 3 of 3
  • Item
    A real-time expert system shell for process control.
    (1990) Kang, Alan Montzy
    A multi-layered expert system shell that specifically addresses real-time issues is designed and implemented. The architecture of this expert system shell supports the concepts of parallelism, concurrent computation and competitive reasoning in that it allows several alternatives to be explored simultaneously. An inference engine driven by a hybrid of forward and backward chanining methods is used to achieve real-time response, and certainty factors are used for uncertainty management. Real-time responsiveness is improved by allowing the coexistence of procedural and declarative knowledge within the same system. A test bed that was set up in order to investigate the performance of the implemented shell is described. It was found in the performance analysis that the proposed system meets the real-time requirements as specified in this research.
  • Item
    A framework for a real-time knowledge based system.
    (1993) Gebbie, Ian
    A framework designed to contain and manage the use of knowledge in a real-time knowledge based system for high level control of an industrial process is presented. A prototype of the framework is designed and implemented on a static objectorientated shell. Knowledge is stored in objects and in forward chaining rules. The knowledge has a well defined structure, making it easy to create and manage. Rules are used to recognize conditions and propose control objectives. The framework uses the knowledge to determine variables that if altered will meet the objectives. Control actions are then found to implement changes to these variables The use of explicit control objectives makes it possible to determine if an action worked as intended and if its use is suitable for the present conditions. This enables a learning mechanism to be applied in the expert system. The prototype operated adequately, but the knowledge required to drive the. system was found to be very detailed and awkward to create.
  • Item
    An error recovery technique for real-time distributed computer systems
    (2016-08-12) Bloch, Gerald
    This thesis studies fault tolerant strategies for real-time distributed computer control systems so as to propose an error recovery technique that renders individual processors on the network resistant to soft failures. The technique is effective for soft failures which have as certain maximum duration, and does not require the use of specialised hardware. Attention is focused on achieving resistance to soft failures in environments which have demanding time constraints such as those found in computer systems for process control, materials handling and automated manufacturing. [Abbreviated Abstract. Open document to view full version]