Doctoral Degrees (Mathematical Statistics and Actuarial Science)

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Browsing Doctoral Degrees (Mathematical Statistics and Actuarial Science) by Author "Mangara, Bernard Tonderayi"

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    On some methods of reliability improvement of engineering systems
    (University of the Free State, 2015-08) Mangara, Bernard Tonderayi; Finkelstein, Maxim
    The purpose of this thesis was to study some methods of reliability improvement of engineering systems. The reason for selecting the theme “reliability improvement of engineering systems” was first to explore traditional methods of reliability improvement (that is, based on the notion that reliability could be assured by simply introducing a sufficiently high “safety factor” into the design of a component or a system) and then propose new and original concepts of reliability improvement. The latter consists of approaches, methods and best practices that are used at the design phase of a component (system) in order to minimize the likelihood (risk) that the component (system) might not meet the reliability requirements, objectives and expectations. Therefore, chapter 1 of the thesis, “Introduction to the main methods and concepts of reliability for technical systems” encompasses the introduction section and the main traditional methods available for improvement of technical / engineering systems. In chapter 2, “Reliability Component Importance Measures” two new and original concepts on reliability improvement of engineering systems are introduced. These are: 1) the study of availability importance of components in coherent systems and 2) the optimal assignment of interchangeable components in coherent multi-state systems. In chapter 3, “Cannibalization Revisited” two new and original concepts on reliability improvement of engineering systems are introduced. These are: 1) theoretical model to show the effects of cannibalization on mission time availability of systems and 2) new model for cannibalization and the corresponding example. In chapter4, “On the Improvement of Steam Power Plant System Reliability” a new and original model is developed that helps in determining the optimal maintenance strategies which will ensure maximum reliability of the coal-fired generating station. Conclusions are given, concerning the study conducted and the results thereof, at the end of each chapter. The conclusions for this thesis are annotated in chapter 5. A set of selected references that were consulted during the study performed for this doctor of philosophy thesis is provided at the end.