Browsing by Author "Hauman, Charlotte"
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- ItemThe application of the cross-entropy method for multi-objective optimisation to combinatorial problems(Stellenbosch : Stellenbosch University, 2012-12) Hauman, Charlotte; Bekker, James F.; Stellenbosch University. Faculty of Engineering. Dept. of Industrial Engineering.ENGLISH ABSTRACT: Society is continually in search of ways to optimise various objectives. When faced with multiple and con icting objectives, humans are in need of solution techniques to enable optimisation. This research is based on a recent venture in the eld of multi-objective optimisation, the use of the cross-entropy method to solve multi-objective problems. The document provides a brief overview of the two elds, multi-objective optimisation and the cross-entropy method, touching on literature, basic concepts and applications or techniques. The application of the method to two problems is then investigated. The rst application is to the multi-objective vehicle routing problem with soft time windows, a widely studied problem with many real-world applications. The problem is modelled mathematically with a transition probability matrix that is updated according to cross-entropy principles before converging to an approximation solution set. The highly constrained problem is successfully modelled and the optimisation algorithm is applied to a set of benchmark problems. It was found that the cross-entropy method for multi-objective optimisation is a valid technique in providing feasible and non-dominated solutions. The second application is to a real world case study in blood management done at the Western Province Blood Transfusion Service. The conceptual model is derived from interviews with relevant stakeholders before discrete event simulation is used to model the system. The cross-entropy method is used to optimise the inventory policy of the system by simultaneously maximising the combined service level of the system and minimising the total distance travelled. By integrating the optimisation and simulation model, the study shows that the inventory policy of the service can improve signi cantly, and the use of the cross-entropy algorithm adequately progresses to a front of solutions. The research proves the remarkable width and simplicity of possible applications of the cross-entropy algorithm for multi-objective optimisation, whilst contributing to literature on the vehicle routing problem and blood management. Results on benchmark problems for the vehicle routing problem with soft time windows are provided and an improved inventory policy is suggested to the Western Province Blood Transfusion Service.
- ItemAn assessment of the implementation of teleradiology in the Eastern Cape towards the enhanced utilisation of the system(Stellenbosch : Stellenbosch University, 2010-12) Hauman, Charlotte; Van Dyk, L.; Stellenbosch University. Faculty of Engineering. Dept. of Industrial Engineering.ENGLISH ABSTRACT: Telemedicine is the use of communication and information technology (ICT) to enable the delivery of specialised health care services. In a developing country like South Africa where there is a shortage of medical specialists, telemedicine is an innovative tool that can contribute to the equitable distribution of resources such as specialist knowledge. The problem is that the past decade has seen numerous telemedicine initiatives being introduced in the country, with little sustainability and low utilisation rates. The initiatives being introduced need to be monitored and evaluated to ensure the sustained implementation and complete adoption of the telemedicine systems in the country. This project focuses on a specific South African telemedicine initiative, the teleradiology system in the Eastern Cape province, with the purpose to provide an assessment of the implementation of the system and a framework towards the enhanced utilisation of the system. Literature is studied comprehensively to find a broad perspective on the factors involved when teleradiology is implemented. Four barriers to the sustained implementation of teleradiology are identified, namely technological, organisational, behavioural and economical barriers. These barriers are discussed with regard to the literature and then the broad perspective is narrowed by applying the literature to various aspects of the Eastern Cape system. This application follows a visit as part of a project team from the Medical Research Council of South Africa and the University of Stellenbosch in June 2010 to monitor and evaluate telemedicine in the Eastern Cape. Research was done using surveys, interviews and observations and valuable exposure to the system was obtained. The four implementation barriers and examples of the Eastern Cape system are integrated into a discussion of the entire teleradiology system. The assessment of the system is concluded with an engineering view point of providing an alternative solution and the evaluation of alternatives. It is anticipated that the project will contribute to the available literature on the sustained implementation of teleradiology and telemedicine in a developing country such as South Africa and provide decision makers and managers of telemedicine in the Eastern Cape with an original view on the system and a framework towards the enhanced implementation of the teleradiology system.