A. James Clark School of Engineering
Permanent URI for this communityhttp://hdl.handle.net/1903/1654
The collections in this community comprise faculty research works, as well as graduate theses and dissertations.
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Item Sensor-Augmented Lightning Mitigation; Implications for Risk at Hydraulic Fracturing Storage Facilities(2015) Rooke, Sterling; Skibniewski, Miroslaw J.; Fuhr, Peter L.; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Hydraulic Fracturing (hydro fracking) has revolutionized oil and gas production in the United States. Controversy has been widespread and plenty of uncertainty remains commonplace in the public. The topic of hazardous chemicals and pollution associated with hydro fracking will be presented in some detail. However, the key focus will be on sensors and lightning mitigation at produced hydrocarbon storage batteries. Unmitigated fires and explosions will be shown to cause $10 million per direct strike in some lightning risk zones. Lightning has stood as an unresolved threat to hydrocarbon storage facilities for over 100 years. Literature research has shown that 33% of all modern hydrocarbon tank accidents are due to lightning (Chang and Lin, 2006); in addition, cloud-ground lightning strikes are predicted to increase by 50% this century (Romps et al., 2014). An overlay of the current National Lightning Detection Network (NLDN) risk map and the Energy Information Administration (EIA) shale play map clearly show the lightning threat only increasing with the migration of future shale activities. While planning may change, shale deposits and regional lightning threats are not changing geographically; this research quantifies the threat and outlines clear lightning mitigation strategies. Furthermore, real-time detection and the associated methodology of lightning mitigation have implications for industries far beyond hydro fracking. By leveraging industrial standards for Fire and Gas Systems (FGS) such as IEC 61511, the proposed lightning effects mitigation system has a pathway toward verification and eventual validation at a broad array of industrial sites. Some extended applications included Navy fuel storage depots and Liquefied Natural Gas (LNG) facilities.Item Mitigation of Acceleration of Vehicles Subjected to Buried Mine Loading(2015) Plitt, Zachary Tyler; Fourney, William; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This dissertation investigates the mitigation of acceleration to passengers on a blast loaded vehicle. Small scale explosive testing was conducted to simulate the detonation of a buried mine on a vehicle. Tests were conducted in saturated sand, which will act as the loading mechanism on the simulated vehicle. Piezoelectric accelerometers, in conjunction with high speed cameras, were used to record test data. Two forms of mitigation were utilized in this research: hull shaping and crushing polyurea-coated thin-walled cylinders. Hull shaping deflects the blast, while the polyurea-coated thin-walled cylinders are crushed to absorb energy. Both forms of mitigation were tested, both separately and together, to determine their effectiveness at mitigating acceleration on the simulated vehicle. The goal of this dissertation is to determine the effectiveness of different mitigation techniques at reducing acceleration in order to design safer military vehicles.Item AVIATION CONGESTION MANAGEMENT IMPROVEMENTS IN MODELING THE PREDICTION, MITIGATION, AND EVALUATION OF CONGESTION IN THE NATIONAL AIRSPACE SYSTEM(2014) Vlachou, Kleoniki; Lovell, David J.; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The air transportation system in the United States is one of the most complex systems in the world. Projections of increasing air traffic demand in conjunction with limited capacity, that is volatile and affected by exogenous random events, represent a major problem in aviation system management. From a management perspective, it is essential to make efficient use of the available resources and to create mechanisms that will help alleviate the problems of the imbalance between demand and capacity. Air traffic delays are always present and the more air traffic increases the more the delays will increase with very unwanted economic impacts. It is of great interest to study them further in order to be able to more effectively mitigate them. A first step would be to try to predict them under various circumstances. A second step would be to develop various mechanisms that will help in reducing delays in different settings. The scope of this dissertation is to look closer at a threefold approach to the problem of congestion in aviation. The first effort is the prediction of delays and the development of a model that will make these predictions under a wide variety of distributional assumptions. The work presented here is specifically on a continuum approximation using diffusion methods that enables efficient solutions under a wide variety of distributional assumptions. The second part of the work effort presents the design of a parsimonious language of exchange, with accompanying allocation mechanisms that allow carriers and the FAA to work together quickly, in a Collaborative Decision Making environment, to allocate scarce capacity resources and mitigate delays. Finally, because airlines proactively use longer scheduled block times to deal with unexpected delays, the third portion of this dissertation presents the assessment of the monetary benefits due to improvements in predictability as manifested through carriers' scheduled block times.Item Small-Scale Testing to Study Mitigation of Acceleration on Simulated Vehicles(2013) Bonsmann, Jarrod; Fourney, William L; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This dissertation investigates various means for mitigating acceleration experienced by passengers on vehicles subjected to blast loading. In order to complete this study, small-scale testing of simulated vehicles was used. The explosives designated for this research are exclusively buried in saturated sand, which will act as the loading media for the simulated vehicles. In addition to explosive testing, various tests were performed dynamically using a high-pressure gas gun. Initially, tests were performed to better understand the effects of vehicle mass and stand-off distance on vehicle acceleration due to blast loads; after which, studies were conducted to mitigate the acceleration. Test plates used in this study vary in both size and geometry. When necessary, simple plate geometries are employed to investigate various mitigation parameters. Ultimately, much of the testing was conducted on simplified scaled versions of vehicles likely to be subjected to attack. This paper focuses mainly on mitigation through crushing of thin-walled cylinders, but also investigates the advantages of applying polymeric coatings to dynamically loaded structures. Piezoelectric accelerometers are used in conjunction with high speed videography to collect test data. In addition to acceleration, impulse and kinetic energy of each test plate is examined. This research, though funded by the US Army, will be of use to all branches of the armed forces utilizing Mine-Resistant Ambush-Protected vehicles. The ultimate goal of this research is to help create a vehicle that will increase the probability that the passengers will survive a blast event with minimal long-term damage to the brain.Item Mitigation of Frame Acceleration Induced by a Buried Charge(2010) Brodrick, Thomas James; Foruney, William; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)In this thesis, methods to mitigate acceleration delivered to the frame of a vehicle with an attached v-shaped hull are investigated. The frame of a vehicle represents an alternative location for crew seating, as opposed to seats being secured to the floorboard. Mitigation techniques were investigated for three test setups: aluminum frame with a downwardly convex aluminum hull, steel frame with a downwardly convex steel hull, and a steel frame with a downwardly concave steel hull. Accelerations of the frame were measured using piezoelectric accelerometers placed at three different locations on the frame. These acceleration measurements were verified against video recorded by high speed cameras. Each test was intended to reduce peak accelerations experienced by the frame, and to reduce the width of the acceleration envelope at large g levels. Mitigation techniques focused on reducing the initial hull-frame interactions, while damping subsequent responses of the system. Mitigation systems and hull orientation were compared for their ability to reduce blast effects experienced by the frame.