Theses and Dissertations from UMD
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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 give thesis/dissertation in DRUM
More information is available at Theses and Dissertations at University of Maryland Libraries.
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Item Solving continuous replenishment inventory routing problems(2008-08-22) Fomundam, Samuel; Herrmann, Jeffrey; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This research investigates the problem of resupplying points of dispensing (PODs), which will dispense medications to millions of people in case of a bioterrorist attack such as anthrax. After receiving an initial but limited supply of medication, the PODs will operate continuously. Vehicles will resupply the PODs continuously from a central depot that has a stockpile of medication. Each vehicle will repeatedly follow the same route and will deliver at each POD enough medication to replace what was consumed since the last visit. Because the number of drivers and trucks may be limited during an emergency, we wish to minimize the number of vehicles used to resupply the PODs. This thesis presents heuristics and a branch-and-bound approach for solving this NP-hard problem and evaluates their performance. We also analyze a special case in which all of the PODs have the same demand.Item Critical Asset and Portfolio Risk Analysis for Homeland Security(2008-07-21) McGill, William L; Ayyub, Bilal M; Reliability Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Providing a defensible basis for allocating resources for critical infrastructure and key resource protection is an important and challenging problem. Investments can be made in countermeasures that improve the security and hardness of a potential target exposed to a security hazard, deterrence measures to decrease the likeliness of a security event, and capabilities to mitigate human, economic, and other types of losses following an incident. Multiple threat types must be considered, spanning everything from natural hazards, industrial accidents, and human-caused security threats. In addition, investment decisions can be made at multiple levels of abstraction and leadership, from tactical decisions for real-time protection of assets to operational and strategic decisions affecting individual assets and assets comprising a regions or sector. The objective of this research is to develop a probabilistic risk analysis methodology for critical asset protection, called Critical Asset and Portfolio Risk Analysis, or CAPRA, that supports operational and strategic resource allocation decisions at any level of leadership or system abstraction. The CAPRA methodology consists of six analysis phases: scenario identification, consequence and severity assessment, overall vulnerability assessment, threat probability assessment, actionable risk assessment, and benefit-cost analysis. The results from the first four phases of CAPRA combine in the fifth phase to produce actionable risk information that informs decision makers on where to focus attention for cost-effective risk reduction. If the risk is determined to be unacceptable and potentially mitigable, the sixth phase offers methods for conducting a probabilistic benefit-cost analysis of alternative risk mitigation strategies. Several case studies are provided to demonstrate the methodology, including an asset-level analysis that leverages systems reliability analysis techniques and a regional-level portfolio analysis that leverages techniques from approximate reasoning. The main achievements of this research are three-fold. First, this research develops methods for security risk analysis that specifically accommodates the dynamic behavior of intelligent adversaries, to include their tendency to shift attention toward attractive targets and to seek opportunities to exploit defender ignorance of plausible targets and attack modes to achieve surprise. Second, this research develops and employs an expanded definition of vulnerability that takes into account all system weaknesses from initiating event to consequence. That is, this research formally extends the meaning of vulnerability beyond security weaknesses to include target fragility, the intrinsic resistance to loss of the systems comprising the asset, and weaknesses in response and recovery capabilities. Third, this research demonstrates that useful actionable risk information can be produced even with limited information supporting precise estimates of model parameters.Item Structuring Biodefense: Legacies and Current Policy Choices(2007-01-23) Okutani, Stacy M.; Steinbruner, John D; Public Policy; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Policies are usually initiated in response to specific circumstances, but they do not become effective unless they are embedded in operating institutions. Understanding the historical process through which policies evolve is essential for assessing their character and their consequence. This study is a detailed history of the US bioweapons program from its inception to the present. It is an original analysis based on archival documents and scientific reports. The issue is, does the application of national security measures such as the classification of scientific programs improve biodefense? Initial organization of the US bioweapons program as a secret, military program that performed threat assessment work (1941-1969) led to the development and stockpiling of biological weapons for deterrence, but few medical defenses. A strategic review in 1969 concluded that bioweapons were not useful for legitimate military missions and did not enhance US deterrence. It also concluded that proliferation threatened the US. To reduce proliferation, the US destroyed its bioweapons arsenal and enforced the norm against bioweapons acquisition by signing the Biological and Toxin Weapons Convention (BWC) in 1972. Subsequent organization of the US biodefense program was as an unclassified military medical research program. This work at the US Army Medical Research Institute of Infectious Diseases (USAMRIID) improved medical countermeasures without a concomitant classified, offensive program. However, in response to the terrorist attacks of 2001, the US is again imposing secrecy over important aspects of its biodefense work, including its threat assessment work. Based on the analysis here, current policy will increase the risk to US security by both enlarging the threat space and reducing defensive options.