published_or_final_version / Industrial Engineering / Master / Master of Science in Engineering

published_or_final_version / Business Administration / Master / Master of Business Administration

published_or_final_version / Business Administration / Master / Master of Business Administration

abstract / Housing Management / Master / Master of Housing Management

published_or_final_version / abstract / Civil Engineering / Doctoral / Doctor of Philosophy

This thesis explores different paradigms for incorporating uncertainty with optimization frameworks for applications in chemical engineering and site-wide operations. First, we address the simulation optimization problem, which deals with the search for optimal input parameters to black-box stochastic simulations which are potentially expensive to evaluate. We include a comprehensive literature survey of the state-of-the-art in the area, propose a new provably convergent trust region-based algorithm, and discuss implementation details along with extensive computational experience, including examples for chemical engineering applications. Next, we look at the problem of long-term site-wide maintenance turnaround planning. Turnarounds involve the disruption of production for significant periods of time, and may incur enormous costs in terms of maintenance manpower as well as lost sales. The problem involves (1) the simulation of profit deterioration due to wear and tear followed by the determination of how frequently a particular turnaround should take place; and (2) the consideration of site network structure and turnaround frequencies to determine how turnarounds of different plants may be coordinated over a long-term horizon. We investigate two mixed-integer models, the first of which determines optimal frequencies of individual plant turnarounds, while the second considers maximizing long-term profit through coordination of turnarounds across the site. We then turn to more conventional methods of dealing with optimization under uncertainty, and make use of a combined robust optimization and stochastic programming approach to medium-term maintenance planning in integrated chemical sites. The nature of the uncertainty considered affects two aspects of maintenance planning, one of which is most suitably addressed through a robust optimization framework, while the other is better handled with stochastic programming models. In summary, we highlight the importance of considering uncertainty in optimization as well as the choice of approach or paradigm used through chemical engineering applications that span varied domains and time scales.

From 1979 through 1984 the economic bases of rural Oregon counties have undergone structural change. Nonwage income, especially transfer payments, has played an important role in these changes. Demographic changes in rural counties have contributed to the growth in unearned income. The economic structure of rural Oregon counties was estimated by applying indirect export analysis techniques to secondary data. The results of the structural analysis provided the data for the econometric analysis. A conceptual model of regional growth was developed that incorporated community characteristics such as the size of the market (population) and market distance (location and commuting activity) from central place theory. This conceptual model was made operational through several econometric models which regressed basic income and community characteristics on residentiary incomes. Data limitations prevented extensive testing of the econometric models. Some bias, which affected the values of the residentiary sectors, was perceived in the estimation of exports. Two methodological improvements were attained. Firstly, the economic base of each county was estimated with sectoral groupings and data disaggregation that were better suited to the analytical techniques than is commonly applied. Secondly, a regional growth model was develped that combined basic income arguments with regional location and population arguments. The growth of expenditures by transfer payments recipients, both as a type of basic income expenditure and as a representative of retiree consumption, helped to account for the growth of residentiary income in rural counties during the early 1980's. Due to the steady growth of transfer payments, the growth of the retiree population and the decline in export earnings, policy makers should specifically consider the changing number of retirees when formulating regional development strategies. / Graduation date: 1988

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As two emerging terms in industry field, “Industry 4.0” and “Cyber-Physical System” have attracted an increasing amount of attention from both researchers and manufactures. Available advanced technologies brought by these terms, offers possible solutions and improvements for future maintenance. The purpose of the thesis is to identify how Industry 4.0 integrates with Cyber-Physical Systems regarding maintenance management and the requirements for companies to reach the ideal smart factory. Two researcher questions were studied to fulfill the purpose. Firstly, identifying the integration between Industry 4.0 and CPS regarding maintenance functions. Secondly, to investigate how such integration contribute to maintenance management in an ideal future factory.