A. James Clark School of Engineering

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The collections in this community comprise faculty research works, as well as graduate theses and dissertations.

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    Lessons Learned from the 787 Dreamliner Issue on Lithium-Ion Battery Reliability
    (MDPI, 2013-09-09) Williard, Nicholas; He, Wei; Hendricks, Christopher; Pecht, Michael
    On 16 January 2013, all Boeing 787 Dreamliners were indefinitely grounded due to lithium-ion battery failures that had occurred in two planes. Subsequent investigations into the battery failures released through the National Transportation Safety Board (NTSB) factual report, the March 15th Boeing press conference in Japan, and the NTSB hearings in Washington D.C., never identified the root causes of the failures—a major concern for ensuring safety and meeting reliability expectations. This paper discusses the challenges to lithium-ion battery qualification, reliability assessment, and safety in light of the Boeing 787 battery failures. New assessment methods and control techniques that can improve battery reliability and safety in avionic systems are then presented.
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    Evaluation of Batteries for Safe Air Transport
    (MDPI, 2016-05-05) Williard, Nicholas; Hendricks, Christopher; Sood, Bhanu; Chung, Jae Sik; Pecht, Michael
    Lithium-ion batteries are shipped worldwide with many limitations implemented to ensure safety and to prevent loss of cargo. Many of the transportation guidelines focus on new batteries; however, the shipment requirements for used or degraded batteries are less clear. Current international regulations regarding the air transport of lithium-ion batteries are critically reviewed. The pre-shipping tests are outlined and evaluated to assess their ability to fully mitigate risks during battery transport. In particular, the guidelines for shipping second-use batteries are considered. Because the electrochemical state of previously used batteries is inherently different from that of new batteries, additional considerations must be made to evaluate these types of cells. Additional tests are suggested that evaluate the risks of second-use batteries, which may or may not contain incipient faults.
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    Determining the Number of Slots to Submit to a Market Mechanism at a Single Airport
    (2007-05-09) Churchill, Andrew Michael; Lovell, David J; Civil Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    In this thesis, several stochastic optimization models are presented to determine the number of airport arrival slots that should be made available for distribution via a market mechanism. Considerable attention is paid to the structure and mathematical properties of each of these models, with regards to obtaining integer-valued solutions. Calibration of the various parameters is undertaken using historical data. In addition, an analysis of the average pecuniary valuations assigned to each slot is presented, as this is an essential input to these models. Several methods are suggested by which each of these values can be estimated. The models are intended to be taken in a general context, but extensive computational examples making use of data for LaGuardia Airport are provided as a case study in the application of the various techniques presented herein.