3 resultados para Critical infrastructures. Fault Tree. Dependability. Framework. Industrialenvironments

em DRUM (Digital Repository at the University of Maryland)


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This study explores the origins and development of honors education at a Historically Black College and University (HBCU), Morgan State University, within the context of the Maryland higher education system. During the last decades, public and private institutions have invested in honors experiences for their high-ability students. These programs have become recruitment magnets while also raising institutional academic profiles, justifying additional campus resources. The history of higher education reveals simultaneous narratives such as the tension of post-desegregated Black colleges facing uncertain futures; and the progress of the rise and popularity of collegiate honors programs. Both accounts contribute to tracing seemingly parallel histories in higher education that speaks to the development of honors education at HBCUs. While the extant literature on honors development at Historically White Institutions (HWIs) of higher education has gradually emerged, our understanding of activity at HBCUs is spotty at best. One connection of these two phenomena is the development of honors programs at HBCUs. Using Morgan State University, I examine the role and purpose of honors education at a public HBCU through archival materials and oral histories. Major unexpected findings that constructed this historical narrative beyond its original scope were the impact of the 1935/6 Murray v Pearson, the first higher education desegregation case. Other emerging themes were Morgan’s decades-long efforts to resist state control of its governance, Maryland’s misuse of Morrill Act funds, and the border state’s resistance to desegregation. Also, the broader histories of Black education, racism, and Black citizenship from Dred Scott and Plessy, the 1863 Emancipation Proclamation to Brown, inform this study. As themes are threaded together, Critical Race Theory provides the framework for understanding the emerging themes. In the immediate wake of the post-desegregation era, HBCUs had to address future challenges such as purpose and mission. Competing with HWIs for high-achieving Black students was one of the unanticipated consequences of the Brown decision. Often marginalized from higher education research literature, this study will broaden the research repository of honors education by documenting HBCU contributions despite a challenging landscape.

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Transportation system resilience has been the subject of several recent studies. To assess the resilience of a transportation network, however, it is essential to model its interactions with and reliance on other lifelines. In this work, a bi-level, mixed-integer, stochastic program is presented for quantifying the resilience of a coupled traffic-power network under a host of potential natural or anthropogenic hazard-impact scenarios. A two-layer network representation is employed that includes details of both systems. Interdependencies between the urban traffic and electric power distribution systems are captured through linking variables and logical constraints. The modeling approach was applied on a case study developed on a portion of the signalized traffic-power distribution system in southern Minneapolis. The results of the case study show the importance of explicitly considering interdependencies between critical infrastructures in transportation resilience estimation. The results also provide insights on lifeline performance from an alternative power perspective.

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The occurrence frequency of failure events serve as critical indexes representing the safety status of dam-reservoir systems. Although overtopping is the most common failure mode with significant consequences, this type of event, in most cases, has a small probability. Estimation of such rare event risks for dam-reservoir systems with crude Monte Carlo (CMC) simulation techniques requires a prohibitively large number of trials, where significant computational resources are required to reach the satisfied estimation results. Otherwise, estimation of the disturbances would not be accurate enough. In order to reduce the computation expenses and improve the risk estimation efficiency, an importance sampling (IS) based simulation approach is proposed in this dissertation to address the overtopping risks of dam-reservoir systems. Deliverables of this study mainly include the following five aspects: 1) the reservoir inflow hydrograph model; 2) the dam-reservoir system operation model; 3) the CMC simulation framework; 4) the IS-based Monte Carlo (ISMC) simulation framework; and 5) the overtopping risk estimation comparison of both CMC and ISMC simulation. In a broader sense, this study meets the following three expectations: 1) to address the natural stochastic characteristics of the dam-reservoir system, such as the reservoir inflow rate; 2) to build up the fundamental CMC and ISMC simulation frameworks of the dam-reservoir system in order to estimate the overtopping risks; and 3) to compare the simulation results and the computational performance in order to demonstrate the ISMC simulation advantages. The estimation results of overtopping probability could be used to guide the future dam safety investigations and studies, and to supplement the conventional analyses in decision making on the dam-reservoir system improvements. At the same time, the proposed methodology of ISMC simulation is reasonably robust and proved to improve the overtopping risk estimation. The more accurate estimation, the smaller variance, and the reduced CPU time, expand the application of Monte Carlo (MC) technique on evaluating rare event risks for infrastructures.