UMD Theses and Dissertations
Permanent URI for this collectionhttp://hdl.handle.net/1903/3
New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a given thesis/dissertation in DRUM.
More information is available at Theses and Dissertations at University of Maryland Libraries.
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Item System Design And Analysis Of A Renewable Energy Source Powered Microgrid(2018) Venegas Zambrana, Miguel Norman; Baras, John S; Systems Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Today there is a great need for alternative new energy sources at cheaper development prices than those required from a traditional power plants. The renewable generation technologies are and will become both cheaper and more beneficial for our environment than other traditional means of productions. As Renewable Energy Generation technologies advance, it is important that Power Systems Engineers investigate carefully the Smart Grid and specially the Islanded Microgrid. Microgrid System Design Solutions that seek zero Emissions are more important as pollutants from traditional plants contribute to the contamination of the environment. In this thesis we use a Systems Engineering approach to design and analyze a typical Islanded Microgrid in order to seek zero emission Microgrids at the lowest possible cost. This study designs the Microgrid as a Smart Grid; we use and follow the design by considering engineering Standards from NIST and IEEE. Then we develop initial Microgrid System design and architecture. The System then is Analyzed and simulated in HOMER. Finally, a Tradeoff analysis is performed to search design variations and their effect on system cost as well as on environmental emissions.Item A Systems Reliability Approach to Flow Control in Dam Safety Risk Analysis(2014) Komey, Adiel; Baecher, Gregory; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Most contemporary risk assessment techniques, such as failure modes and effect analysis (FMEA), fault tree analysis (FTA), and probabilistic risk analysis (PRA) rely on a chain-of-event paradigm of accident causation. Event-based techniques have some limitations for the study of modern engineering systems; specifically hydropower dams. They are not suited to handle complex computer-intensive systems, complex human-machine interactions, and systems-of-systems with distributed decision-making that cut across both physical and organizational boundaries. The emerging paradigm today, however, is not to analyze dam systems separately by breaking the major disciplines into stand-alone vertical analyses; but to explore the possibilities inherent in taking a systems approach to modeling the reliability of flow-control functions within the entire system. This dissertation reports on the development and application of systems reliability models to operational aspects of a hydropower cascade in Northern Ontario: The Lower Mattagami River (LMR) Project operated by Ontario Power Generation (OPG). The reliable performance of a spillway system depends on the many environmental and operational demand functions placed upon it by basin hydrology, the hydraulic conditions at reservoirs and dams, operating rules for the cascade of reservoirs in the basin, and the vagaries of human and natural factors such as operator interventions or natural disturbances such as ice and floating debris (Regan, 2010). These systems interact to control floods, condition flows, and filter high frequencies in the river discharge. Their function is to retain water volumes and to pass flows in a controlled way. The reliability of flow-control systems is a broad topic that covers structural, mechanical, electrical, control systems and subsystems reliability, as well as human interactions, organization issues, policies and procedures. All 3 of these occur in a broad spectrum of environmental conditions. A systems simulation approach is presented for grappling with these varied influences on flow-control systems in hydropower installations. The Mattagami River cascade operated by Ontario Power Generation is a series of four power stations along the Mattagami River and the Adams Creek bypass channel from Little Long GS at the top to the cascade to the Mattagami River below Kipling GS at the bottom. The number of riparians in the river flood plain is few and there is no commercial riverine navigation, so potential loss of life is small or negligible and operational safety dominates. Upstream of Little Long dam is a seasonally-varying inflow and a reservoir. The remaining three dams downstream (Smokey Falls, Harmon, and Kipling) have little storage capacity. Each dam has two vertical lift gates and all four structures have approximately the same spillway capacity. Far downstream, the river discharges into Hudson's Bay. Hydrological and climate frequency data are available for a period of 50 years. The problem facing the project was to conceptualize a systems engineering model for the operation of the dams, spillways, and other components; then to employ the model through stochastic simulation to investigate protocols for the safe operation of the spillway and flow control system. Details of the modeling, analysis, and results for safe operation of the cascade are presented.Item Systems-compatible Incentives(2010) Levin, David; Bhattacharjee, Samrat; Computer Science; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Originally, the Internet was a technological playground, a collaborative endeavor among researchers who shared the common goal of achieving communication. Self-interest used not to be a concern, but the motivations of the Internet's participants have broadened. Today, the Internet consists of millions of commercial entities and nearly 2 billion users, who often have conflicting goals. For example, while Facebook gives users the illusion of access control, users do not have the ability to control how the personal data they upload is shared or sold by Facebook. Even in BitTorrent, where all users seemingly have the same motivation of downloading a file as quickly as possible, users can subvert the protocol to download more quickly without giving their fair share. These examples demonstrate that protocols that are merely technologically proficient are not enough. Successful networked systems must account for potentially competing interests. In this dissertation, I demonstrate how to build systems that give users incentives to follow the systems' protocols. To achieve incentive-compatible systems, I apply mechanisms from game theory and auction theory to protocol design. This approach has been considered in prior literature, but unfortunately has resulted in few real, deployed systems with incentives to cooperate. I identify the primary challenge in applying mechanism design and game theory to large-scale systems: the goals and assumptions of economic mechanisms often do not match those of networked systems. For example, while auction theory may assume a centralized clearing house, there is no analog in a decentralized system seeking to avoid single points of failure or centralized policies. Similarly, game theory often assumes that each player is able to observe everyone else's actions, or at the very least know how many other players there are, but maintaining perfect system-wide information is impossible in most systems. In other words, not all incentive mechanisms are systems-compatible. The main contribution of this dissertation is the design, implementation, and evaluation of various systems-compatible incentive mechanisms and their application to a wide range of deployable systems. These systems include BitTorrent, which is used to distribute a large file to a large number of downloaders, PeerWise, which leverages user cooperation to achieve lower latencies in Internet routing, and Hoodnets, a new system I present that allows users to share their cellular data access to obtain greater bandwidth on their mobile devices. Each of these systems represents a different point in the design space of systems-compatible incentives. Taken together, along with their implementations and evaluations, these systems demonstrate that systems-compatibility is crucial in achieving practical incentives in real systems. I present design principles outlining how to achieve systems-compatible incentives, which may serve an even broader range of systems than considered herein. I conclude this dissertation with what I consider to be the most important open problems in aligning the competing interests of the Internet's participants.