Comparison of deterministic, stochastic and fuzzy logic uncertainty modelling for capacity extension projects of DI/WFI pharmaceutical plant utilities with variable/dynamic demand

The last 30 years have seen Fuzzy Logic (FL) emerging as a method either complementing or challenging stochastic methods as the traditional method of modelling uncertainty. But the circumstances under which FL or stochastic methods should be used are shrouded in disagreement, because the areas of application of statistical and FL methods are overlapping with differences in opinion as to when which method should be used. Lacking are practically relevant case studies comparing these two methods. This work compares stochastic and FL methods for the assessment of spare capacity on the example of pharmaceutical high purity water (HPW) utility systems. The goal of this study was to find the most appropriate method modelling uncertainty in industrial scale HPW systems. The results provide evidence which suggests that stochastic methods are superior to the methods of FL in simulating uncertainty in chemical plant utilities including HPW systems in typical cases whereby extreme events, for example peaks in demand, or day-to-day variation rather than average values are of interest. The average production output or other statistical measures may, for instance, be of interest in the assessment of workshops. Furthermore the results indicate that the stochastic model should be used only if found necessary by a deterministic simulation. Consequently, this thesis concludes that either deterministic or stochastic methods should be used to simulate uncertainty in chemical plant utility systems and by extension some process system because extreme events or the modelling of day-to-day variation are important in capacity extension projects. Other reasons supporting the suggestion that stochastic HPW models are preferred to FL HPW models include: 1. The computer code for stochastic models is typically less complex than a FL models, thus reducing code maintenance and validation issues. 2. In many respects FL models are similar to deterministic models. Thus the need for a FL model over a deterministic model is questionable in the case of industrial scale HPW systems as presented here (as well as other similar systems) since the latter requires simpler models. 3. A FL model may be difficult to "sell" to an end-user as its results represent "approximate reasoning" a definition of which is, however, lacking. 4. Stochastic models may be applied with some relatively minor modifications on other systems, whereas FL models may not. For instance, the stochastic HPW system could be used to model municipal drinking water systems, whereas the FL HPW model should or could not be used on such systems. This is because the FL and stochastic model philosophies of a HPW system are fundamentally different. The stochastic model sees schedule and volume uncertainties as random phenomena described by statistical distributions based on either estimated or historical data. The FL model, on the other hand, simulates schedule uncertainties based on estimated operator behaviour e.g. tiredness of the operators and their working schedule. But in a municipal drinking water distribution system the notion of "operator" breaks down. 5. Stochastic methods can account for uncertainties that are difficult to model with FL. The FL HPW system model does not account for dispensed volume uncertainty, as there appears to be no reasonable method to account for it with FL whereas the stochastic model includes volume uncertainty.

Thomas Davis's education policies: theory and practice

This thesis explores the education policies of Thomas Davis. On the eve of the Great Famine Ireland was economically impoverished and politically dependent. The Irish people had a subservient mentality, were mainly uneducated and were unaware of their potential. He believed that education would develop a self-reliant, self-sufficient people; it would create a new generation of leaders and citizens necessary to transform Ireland into a prosperous, independent nation. This thesis explores his education philosophy which was political in orientation; he called for reform of university education so that it would educate leaders who were knowledgeable, patriotic and responsible. He formulated a curriculum which consisted of knowledge that would have direct use and application in public life; his curriculum included moral philosophy, oratory, philological studies and history. His contribution to the debate on the Queens Colleges bill, 1845, is explored including his public disagreement with Daniel O’Connell on the principle of multi-denominational education. This work also examines his policies on learning methodologies and teaching methods. It provides details of his thoughts on learning by experience, by observation, book learning and learning in the home. It focuses on the deficiencies evident in the system of teaching and learning that operated in Trinity College Dublin and it provides an analysis of his preferred method of instruction: Lyceum teaching. This thesis also explores his national curriculum in history and Irish culture which was designed to forge a sense of national identity, to win support for repeal and to develop the principle of nationality. He formulated a national curriculum to counteract the absence of national knowledge in the state schools, to provide the people with a positive self-image and ultimately to empower them to reclaim Ireland and to develop it. Davis knew the power of education and he used it as an instrument of political and social change.