This MS thesis studies the effect of uncertainty in the demand of finished products, supply of raw materials, and maintenance resources availability on the maintenance schedule of a manufacturing facility. A simulation model is formulated in order to realistically model manufacturing systems of various complexities, consisting of multiple interacting machines that degrade and fail over time, and are repaired using imperfectly available maintenance crews and resources. A design of experiments (DOE) based sensitivity study is conducted to find the system parameters that mostly affected the maintenance decisions and corresponding profits. / text

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Methodical maintenance and renewal of infrastructure systems is critical due to the rapid deterioration of infrastructure assets under increasing loads and environmental effects and the scarcity of resources allocated for their preservation. A crucial step in pavement management is the formation and prioritization of maintenance and rehabilitation (M&R) projects that compete for limited funding for inclusion in the agency’s multiyear pavement management plan (PMPs). In general, many highway agencies perform this task subjectively, and thus a more rational and objective approach is desired to produce sound and justifiable PMPs. Specifically, such methodology should take into account the multiple factors that are considered by engineers in prioritizing M&R projects. This research addresses this need by developing a methodology for use by the Texas Department of Transportation (TxDOT) in preparing their four-year PMPs. Several key decision factors were considered and TxDOT decision makers were surveyed to weigh these factors as to their influence on prioritizing M&R projects. These were then used to develop a priority score for each candidate M&R project. Since TxDOT collects and stores data for individual 0.5-mile pavement sections, these sections must be grouped in a logical scheme to form realistic candidate M&R projects. The incremental benefit-cost analysis was performed on the candidate M&R projects to identify a set of M&R projects that maximizes network’s priority score under budgetary constraint. Future pavement condition was projected using performance prediction models and the process is repeated throughout the planning horizon to produce a multi-year pavement management plan. Data from Bryan district, which consists of 7,075 lane-miles of roadway, were used to develop and validate the PMP methodology. Comparison with the actual PMP (produced by TxDOT) shows some disagreements with the PMP generated by the methodology though the latter was shown to produce more cost-effective and defendable pavement management plans. Since the methodology is founded on TxDOT engineers’ decision criteria and preferences, they can be assured that the PMPs produced by this methodology are in line with their goals and priorities.

This thesis presents and analyses a solution to the problem of formally re- engineering program data structures, allowing new representations of a program to be developed. The work is based around Ward's theory of program transformations which uses a Wide Spectrum Language, WSL, whose semantics were specially developed for use in proof of program transformations. The re-engineered code exhibits equivalent functionality to the original but differs in the degree of data abstraction and representation. Previous transformational re-engineering work has concentrated upon control flow restructuring, which has highlighted a lack of support for data restructuring in the maintainer's tool-set. Problems have been encountered during program transformation due to the lack of support for data re-engineering. A lack of strict data semantics and manipulation capabilities has left the maintainer unable to produce optimally re-engineered solutions. It has also hindered the migration of programs into other languages because it has not been possible to convert data structures into an appropriate form in the target language. The main contribution of the thesis is the Data Re-Engineering and Abstraction Mechanism (DREAM) which allows theories about type equivalence to be represented and used in a re-engineering environment. DREAM is based around the technique of "ghosting", a way of introducing different representations of data, which provides the theoretical underpinning of the changes applied to the program. A second major contribution is the introduction of data typing into the WSL language. This allows DREAM to be integrated into the existing transformation theories within WSL. These theoretical extensions of the original work have been shown to be practically viable by implementation within a prototype transformation tool, the Maintainer's Assistant. The extended tool has been used to re-engineer heavily modified, commercial legacy code. The results of this have shown that useful re-engineering work can be performed and that DREAM integrates well with existing control flow transformations.

This research analyzes case studies of Korean immigrant families in Canada regarding their attitudes and efforts toward Korean language maintenance. Through the life experiences of Korean immigrant families, this study examines 1) the role of the Korean language in Korean immigrant families, 2) parenting methods and attitudes towards maintaining the use of the Korean language, 3) challenges regarding cultural adaptation, and 4) the effects of Korean language loss within Korean immigrant families. Perspectives from Korean immigrant parents will be explored to examine how Korean language loss impacts the family in the context of relationships, cultural values, and identities. Furthermore, the ability of future generations of Korean immigrant families to maintain the Korean language will be discussed. Finally, the study will suggest alternative approaches to maintaining the Korean language to assist Korean immigrants in the future.

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Wind power, as a source of renewable energy, is growing very fast. Especially so, is consideration given to offshore wind farms where expansion is due in part to limited social and visual impact, reduced noise effect of turbines, and at the same time higher production of offshore wind turbines. Maintenance is always a considerable and costly part of the wind power investment, especially for offshore projects, but it could not improve as fast as the increasing wind industry in the world. The operation and maintenance management of wind farms should have always a reliable and structured planning to have an economical investment. At the beginning of the growth of wind industry, companies tried to transfer responsibilities of the failure and loss of production to the insurance companies, but it cannot be continued any more. These days even the insurance companies ask about regular inspection or condition monitoring. In other words, they ask for a reliable strategy for operation and maintenance. Both preventative and corrective maintenance are used in offshore wind farms. Preventive maintenance is usually performed at the first sign of failure, and in so doing it helps reduce costs associated from lost production. Having a perfect preventive maintenance program is not easy and it usually needs more inspection and online monitoring. To select a suitable strategy, data should be gathered from different stakeholders who are involved in the project. The stakeholders could be turbine designers, construction companies, transportation companies, operation staff, etc. The reason is that each group has the data which could help to define a reliable strategy of maintenance. Reliability includes measurements, e.g., failure rate, repair time, and availability. Reliability is the ability of components or system to perform their function under given operational condition and for a predicted period of time. However always preventive maintenance especially for offshore wind farm is faced with uncertainty due to bad weather, access difficulty, and logistic limitation. Reliability Centered Maintenance (RCM) is a systematic qualitative technique that balances preventive and corrective maintenance. It chooses the right preventive maintenance activities for the right component at the right time to reach the most cost efficient solution. This research points out that RCM, as an experienced methodology in other industries, could be a good method for scheduled preventive maintenance in offshore wind power for purposes of lowering cost while improving reliability and safety. RCM implementation is always facing with uncertainty. Engaged uncertainty to RCM is known as Reliability and Risk Centered Maintenance RRCM and it could lead maintenance process to an optimal preventive schedule with minimum uncertainty.

Sandvik Coromant in Gimo, Sweden, is a world- leading supplier of tools and know- how for the metal cutting industry. This thesis was carried out on the maintenance division at the production plant producing tools for milling and drilling. The maintenance division is responsible for the maintenance of the machinery operating at all eight production units on the tool production plant. This thesis aims to map the value flow and non- value adding activities on the maintenance division and come up with suggestions for improvement. The study only focuses on the organizations work procedures and routines. The thesis began with a current state analysis of the maintenance division to find out how the activities, databases and service technicians interacts in daily operations. A time study showed that the proportion of non-value adding activities in some isolated cases was as low as 30%. The thesis ended in a root cause analysis, in form of a workshop, which aimed to, with help from the service technicians’ expertise and the researchers’ knowledge of lean production come up with solutions worth implementing on the maintenance division. The root cause analysis resulted in three solutions, which the researchers along with the service technicians sees as simple actions that will reduce the non-value adding time associated with the use, and handling of documentation. The analysis also resulted in sex actions seen as worth implementing, which however is more recourse demanding for the organization. / Sandvik Coromant i Gimo, Sverige, är en världsledande leverantör av verktyg och know- how för metallbearbetningsindustrin. Detta arbete utfördes på underhållsavdelningen vid fabriken för tillverkning av verktyg för borrning och fräsning. Underhållsavdelningen är ansvarig för underhållet av maskinparken på alla de åtta produktionsavsnitten vid fabriken för verktygstillverkning. Arbetet syftar till att kartlägga värdeflödet och icke värdeskapande tid vid underhållsavdelningen och komma med förbättringsförslag. Studien fokuserar enbart på organisationens arbetssätt och rutiner. Arbetet började med en nuvärdesanalys av underhållsavdelningen för att undersöka hur aktiviteter, databaser och servicetekniker fungera tillsammans i den dagliga verksamheten. En tidsstudie genomfördes för att undersöka hur mycket icke värdeskapande tid serviceteknikerna har vid en standardarbetsorder från produktionsavsnitten. Tidsstudien visade att andelen icke värdeskapande tid var så låg som 30 % i vissa isolerade fall. Arbetet avslutades i en rotorsaksanalys i form av en workshop, vilkens syfte var att med hjälp från serviceteknikerna och deras expertis tillsammans med kunskapen om lean production hos forskarna undersöka vilka lösningar som skulle minska denna siffra ytterligare. Rotorsaksanalysen resulterade i tre lösningar som forskarna tillsammans med serviceteknikerna ser som enkla åtgärder för att minska den icke värdeskapande tiden kopplad till användning och hantering av dokumentation. Analysen resulterade även i sex åtgärder som anses vara värd att implementera men som är mer resurskrävande för organisationen.