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 THE IMPACT OF PUBLIC MANAGEMENT REGIMES ON TIME-BASED DEFENSE INNOVATION(2021) Greenwalt, William Charles; Joyce, Philip G; Public Policy; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Time was a significant factor in shaping disruptive defense innovation solutions in World War II and the early Cold War. During this period, significant advances were made in military aircraft, missiles, submarines, electronics, and other technologies that were achieved through a time-based development approach of rapid experimentation and operational prototyping. Since the 1960s, however, the time taken to develop and deploy U.S. military systems has significantly increased. This increase corresponded to a shift in emphasis within the public management regimes established to govern defense innovation to one of predominately controlling cost. A systems analysis approach to defense management gained prominence during the Kennedy Administration and emphasized cost analysis, program budgeting, and centralized planning and control from within the Office of the Secretary of Defense as a means to obtain greater efficiency in defense spending. This framework was implemented through a series of linear processes overseen by compartmented management regimes such as the requirements, budget, acquisition, and contracting functions in a structure institutionalized in law and regulation. These linear processes evolved in a way that increased the minimum time to conduct defense innovation that far exceeded previous developmental timelines. Compounding the problem of linearity, government-unique processes and requirements within defense management regimes have created barriers to the civil-military integration of the industrial base. This has furthered the establishment of a narrow, specialized defense industrial base by excluding from the defense market those commercial companies that innovate quickly within time-based constraints. While periodic end-rounds to management regimes were created when the Department needed to rapidly innovate in an emergency or to access innovation from the larger commercial market, these efforts have been at the margins of expenditures and were eventually constrained by the traditional management regimes. A broader ability to reduce innovation times or expand the defense industrial base will require systematic change to address process linearity and civil-military integration barriers.Item TRUST-BASED DEFENSE AGAINST INSIDER PACKET DROP ATTACKS IN WIRELESS SENSOR NETWORKS(2013) Cho, Youngho; Qu, Gang; Electrical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)In most wireless sensor networks (WSNs), sensor nodes generate data packets and send them to the base station (BS) by multi-hop routing paths because of their limited energy and transmission range. The insider packet drop attacks refer to a set of attacks where compromised nodes intentionally drop packets. It is challenging to accurately detect such attacks because packets may also be dropped due to collision, congestion, or other network problems. Trust mechanism is a promising approach to identify inside packet drop attackers. In such an approach, each node will monitor its neighbor's packet forwarding behavior and use this observation to measure the trustworthiness of its neighbors. Once a neighbor's trust value falls below a threshold, it will be considered as an attacker by the monitoring node and excluded from the routing paths so further damage to the network will not be made. In this dissertation, we analyze the limitation of the state-of-the-art trust mechanisms and propose several enhancement techniques to better defend against insider packet drop attacks in WSNs. First, we observe that inside attackers can easily defeat the current trust mechanisms and even if they are caught, normally a lot of damage has already been made to the network. We believe this is caused by current trust models' inefficiency in distinguishing attacking behaviors and normal network transmission failures. We demonstrate that the phenomenon of consecutive packet drops is one fundamental difference between attackers and good sensor nodes and build a hybrid trust model based on it to improve the detection speed and accuracy of current trust models. Second, trust mechanisms give false alarms when they mis-categorize good nodes as attackers. Aggressive mechanisms like our hybrid approach designed to catch attackers as early as possible normally have high false alarm rate. Removing these nodes from routing paths may significantly reduce the performance of the network. We propose a novel false alarm detection and recovery mechanism that can recover the falsely detected good nodes. Next, we show that more intelligent packet drop attackers can launch advanced attacks without being detected by introducing a selective forwarding-based denial-of-service attack that drops only packets from specific victim nodes. We develop effective detection and prevention methods against such attack. We have implemented all the methods we have proposed and conducted extensive simulations with the OPNET network simulator to validate their effectiveness.