Reactive repair of a disrupted schedule is a better alternative to total rescheduling, as the latter is a time consuming process and also results in shop floor nervousness. The schedule repair heuristics reported in the literature generally address only machine breakdown. This paper presents a modified Affected Operations Rescheduling (mAOR) approach, which deals with many of the disruptions that are frequently encountered in a job shop. The repair of these disruptions has been decomposed into four generic repair actions that can be applied singularly or in combination. These generic repair actions are evaluated through a simulation study with the performance measures of efficiency and stability. The results indicate the effectiveness of the mAOR heuristic in dealing with typical job shop disruptions. / Singapore-MIT Alliance (SMA)

Public dependence on air transportation has grown to its largest point in history. Along with this increased dependence is a heightened awareness of safety concerns and the need for pilots to cover all scheduled flights. All commercial pilots are certified for the particular aircraft they are flying by satisfactorily completing a Federal Aviation Administration (FAA) approved course. During the training course, a number of training devices are used including a Full Flight Simulator (FFS) and a Flight Training Device (FTD). The procurement, installation, operation, and maintenance costs of these devices are expensive. In addition, the amount of time pilots spend in training is costly because they continue to be paid their salary rate although they are unable to fly revenue-generating flights for the airline. Due to these high costs, training is scheduled very tightly, with the goals of maximizing training device utilization and minimizing the pilot's training footprint (time spent in training). Any disruption to the tight schedule, such as a simulator breakdown, or pilot illness, renders the original schedule obsolete and demands rescheduling of activities. In this research, the rescheduling problem is investigated through the development and application of several different rescheduling approaches. The problem is decomposed by first investigating a single resource model and insights gained from this experimentation are transferred to the multiple resource model. The solution approaches developed for experimentation include: right-shift rescheduling (RSR), rescheduling of affected activities (RAFF), and rescheduling of all activities (RALL). Performance measures used to compare the various approaches include the minimization of the pilot footprint, the minimization of pilot tardiness, and the minimization of the deviation that a revised schedule has from the original schedule. A case study and a series of experiments involving random disruptions to original schedules were used to analyze the solution approaches. For the data sets analyzed, the RAFF algorithm outperformed other methods with respect to the majority of the measure collected. Analysis performed on the amount of slack in the original schedule revealed that diminishing returns were observed beyond a certain level of slack. Further analysis on the impact of the location of this slack showed that the majority of the slack should be placed at the end of the schedule, or the slack should be dispersed almost evenly over the entire schedule. / Master of Science

Disruptions in the supply chain are becoming more common as supply chains become more complex, and supply chain managers of warehouse distribution centers need strategies to minimize the impact of disruptions. In this study, the focus of the research questions was on strategies supply chain managers could use to mitigate the impact of disruptions. The conceptual frameworks for this study were the resource dependence theory and the normal accident theory, which link supply chain disruptions with resource availability and the inability to eliminate disruptions. An exploratory case study involved exploring how supply chain managers of a warehouse distribution center in Jacksonville, Florida, successfully used strategies to mitigate the impact of a disruption after it occurred. Data came from responses to semistructured interview questions from these managers (n = 6) and archival documents related to policies, procedures, and business continuity planning of a warehouse distribution center in Jacksonville, Florida. I analyzed the data by using Atlas.ti qualitative analysis software. There were 6 themes that emerged: collaborating to minimize the impact of disruptions, disruptions precursors, identifying and assessing impact of disruptions, resources used to minimize impact of disruption, strategies to mitigate disruptions, and supplier relationships. The results could contribute to social change by minimizing the negative effects disruptions have on an organization's profitability and performance. Social change can come from business leaders who are able to maintain and sustain their businesses after a supply chain disruption has occurred.

Supply chain disruptions are more prevalent in Ghana as businesses develop and become more complex. While business leaders recognize the importance of reducing the exposure to disruptions, 83 % of companies still suffer a form of disruption. Using the systems theory as the conceptual framework, the purpose of this qualitative case study was to explore strategies supply chain managers in Ghana use to reduce disruptions in the supply chain. The data collection was through face-to-face, semi-structured interviews from 12 supply chain managers who gave tape-recorded interview responses to 8 questions. Transcript evaluation, member checking, and methodological triangulation ensured reliability and strengthened the credibility of the data collected. Data analysis revealed 6 themes, which included identification of disruptions before they occur, information sharing and collaboration between partners, management strategies to mitigate supply chain disruptions, inventory optimization, availability of human capital, energy, and finance problems. The identification of disruptions was important to participants because they believed if they identified potential disruptions they might prevent them from happening. The collaboration between partners was important because participants believed that the speed at which stakeholders work together after a disruption determines the extent of the cost and the recovery period. Business leaders could apply the findings to provide insight to businesses to reduce disruptions, improve best practices, and increase business profits. Implications for social change include the enhancement of company profits given efficiencies in the supply chain. Such increase in profits leads to increases in taxes, which contributes to the overall betterment of the local communities.

While lean manufacturing has greatly improved the efficiency of production operations, it has left US enterprises in an increasingly risky environment. Causes of manufacturing disruptions continue to multiply, and today, seemingly minor disruptions can cause cascading sequences of capacity losses. Historically, enterprises have lacked viable tools for addressing operational volatility. As a result, each year US companies forfeit billions of dollars to unpredictable capacity disruptions and insurance premiums. In this dissertation we develop a number of stochastic models that capture the dynamics of capacity disruptions in complex multi-tier flow-matching feed-forward networks (FFN). In particular, we relax basic structural assumptions of FFN, introduce random propagation times, study the impact of inventory buffers on propagation times, and make initial efforts to model random network topology. These stochastic models are central to future methodologies supporting strategic risk management and enterprise network design.

Background: Reshoring is a growing phenomenon that refers to a company’s decision to move production back from a previously offshored location. There are many drivers and barriers to such decisions that display an increased complexity for managers. It gets even more challenging in a world with high levels of uncertainty shown in the past decade.    Purpose:  This study aims to investigate the drivers and barriers of reshoring and how managers perceive the risk of disruptive events as a driver of reshoring.    Method: This study uses a qualitative method and deductive approach, where empirical evidence was collected through semi-structured interviews with eight managers at clothing companies.   Conclusion: The findings of this study confirm several already established drivers and barriers to reshoring in the particular context of the clothing industry. Furthermore, the study shows that managers perceive an increased willingness to reshore as a response to disruptive events. This was to a large extent due to long lead times and higher coordination costs. Managers can use the findings as support in making decisions of where to locate their production.

I should like to have completed this process by having this project bound so that it read from right to left instead of the traditional manner in which we have learnt and been taught to read. In partaking of such an activity, it would have been my purpose and intention to share with you my sense of physical discomfort that has situated itself beside me at various stages from the on-set of my research. Because I believe in this process, I have decided to follow a traditional approach, and as you can see it reads as it should from left to right. In the introductory phase of this study, I assert quite unequivocally that this is not a thesis. Instead I promote this as a prolegomena; an interlocutory prolusion. But don't be deceived! This is very much a thesis. It has been researched according to guidelines, formatted according to specifications and ethically undertaken. I want you to believe that it is a thesis. Partially because I have pursued this research in a very serious manner and also because no matter how much we try to avoid becoming enmeshed in a system, ultimately we find that we are. Three years ago I embarked on a quest. At this time, I proposed that I would undertake a study on the Historical Understandings of passion throughout the Western World. This idea came to a sudden and dramatic halt, through the encountering of what I should like to refer to as a series of problems. In order to do justice to my subject, I decided to write about these obstacles, a decision that I hoped would lead me back to my original statement of intent, following their reconciliation. It is Michel Foucault, that I credit with the title for this thesis. After reading his book entitled "This Is Not A Pipe" (1982) I felt a certain sense of inspiration and ethical obligation that I considered worth taking the risk for. Due to no longer writing a thesis on passion, I decided that this could not be called a thesis. It could only be an introduction to my thesis that would speak about why it had become impossible for me to pursue my thesis at this stage. The other reason that this carries the title of this is not a thesis, surrounds my favouring the post-modern over any other position that I have inquired about. This prolusion involves a discussion surrounding many of the problematics associated with my research processes. These include extensively looking at existing methodologies available when undertaking research today. Adjunct to the illumination of these problems, I look at literary disruptions; my penchant for knowledge and my naive aspirations which all contributed to thwarting my journey into completing an adequate study on passion. Included in this prolegomena, are two diagrammatic representations of passion. The first seeks to re-inscribe through re-presenting passion away from its traditional juxtaposition with love or sexual gratification. It re-presents passion as a polyvalent movement that is vastly more complicated than that to which we have come to believe in through out the centuries. Accompanying this depiction, are the traditional notions of passion. This is based on the works of authors such as Aquinas, Daly, Cicero and McLellan. In the conclusion of this prolusion, I suggest that there is a need to re-write a new methodology. One that transcends our current juncture that promotes stances belonging to foundationalism, anti-foundationalism and non-foundationalism. It is my ardent belief, that this is a necessary course of action and will enable the subject of passion to be spoken to as never before.

The aim of this thesis is to identify communication challenges in micro-organizations. Thisthesis defines theoretical areas such as organizational communication and internalcommunication, with a focus on competence, uncertainty, and work disruptions. The methodsused in the collection of empirical material were participant observation, semi-structuredinterviews, and an e-mail survey. This material in combination with the theoretical backgroundhas showed the importance of technical competence in order for employees to be ableto communicate effectively. The technological solutions available today have the potential tomake a workplace much more effective and efficient by using new equipment andcommunication methods, but reaching this potential requires that everyone feels comfortablewith the use and has sufficient competence. The results indicate that since microorganizationshave only a few employees, technical competence needs to be high for everyemployee. The study also reveals the lack of a theoretical framework to evaluate the resourcesrequired for optimal communication in organizations or businesses, and introduces asuitable framework for later studies.

Protection of critical national infrastructure has received significant attention in the past recent years. As a result, researchers have developed methods to preserve and maintain critical infrastructure systems and minimize their vulnerability to disasters and disruptions. However, these models are often customized to meet the characteristics and functionality requirements for a particular system, and are computationally intensive and require simplifying assumptions. In this study, we first develop a tractable and relatively comprehensive model for optimizing maintenance planning of generic network-structured systems. We considered both linear and nonlinear objective functions for our problems. We then reformulate the model in order to enhance its computational effectiveness for large scale complex problems. The proposed modeling framework inherently captures the network topography, the stochastic nature of disruptions, and can be applied to network-structured systems for which performance is assessed based on network flow efficiency and mobility. A hypothetical small-sized network is used to illustrate the developed models, and the pro- posed models are also applied to analyze a larger scale real network in order to assess their relative computational effectiveness and robustness. We selected the Istanbul highway net- work for the latter purpose because of its critical location and also because it has been considered in previous studies, which enables us to compare the effectiveness of our models with an existing model in the literature. We designed several test cases (considering single and multiple treatment types, and linear and nonlinear objectives), and solved them on the NEOS server using different available software. The results demonstrate that our models are capable of attaining optimal solutions within a very short time. Furthermore, the linear model is shown to yield a good approximation to the nonlinear model (it determined solutions within 0.3% of optimality, on average). Moreover, in both cases (our hypothetical illustrative example and the Istanbul highway network), the optimal policies obtained appear to favor the selection of fewer links and to apply a higher quality treatment to them. / Master of Science

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