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Theses and Dissertations

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Articles 2011 - 2040 of 2733

Full-Text Articles in Computer Sciences

Multi-Dimensional Range Querying Using A Modification Of The Skip Graph, Gregory J. Brault Mar 2007

Multi-Dimensional Range Querying Using A Modification Of The Skip Graph, Gregory J. Brault

Theses and Dissertations

Skip graphs are an application layer-based distributed routing data structure that can be used in a sensor network to facilitate user queries of data collected by the sensor nodes. This research investigates the impact of a proposed modification to the skip graph proposed by Aspnes and Shah. Nodes contained in a standard skip graph are sorted by their key value into successively smaller groups based on random membership vectors computed locally at each node. The proposed modification inverts the node key and membership vector roles, where group membership is computed deterministically and node keys are computed randomly. Both skip graph …

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Heuristically Driven Search Methods For Topology Control In Directional Wireless Hybrid Network, Roger L. Garner Mar 2007

Heuristically Driven Search Methods For Topology Control In Directional Wireless Hybrid Network, Roger L. Garner

Theses and Dissertations

Information and Networked Communications play a vital role in the everyday operations of the United States Armed Forces. This research establishes a comparative analysis of the unique network characteristics and requirements introduced by the Topology Control Problem (also known as the Network Design Problem). Previous research has focused on the development of Mixed-Integer Linear Program (MILP) formulations, simple heuristics, and Genetic Algorithm (GA) strategies for solving this problem. Principal concerns with these techniques include runtime and solution quality. To reduce runtime, new strategies have been developed based on the concept of flow networks using the novel combination of three well-known …

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An Artificial Immune System-Inspired Multiobjective Evolutionary Algorithm With Application To The Detection Of Distributed Computer Network Intrusions, Charles R. Haag Mar 2007

An Artificial Immune System-Inspired Multiobjective Evolutionary Algorithm With Application To The Detection Of Distributed Computer Network Intrusions, Charles R. Haag

Theses and Dissertations

Today's predominantly-employed signature-based intrusion detection systems are reactive in nature and storage-limited. Their operation depends upon catching an instance of an intrusion or virus after a potentially successful attack, performing post-mortem analysis on that instance and encoding it into a signature that is stored in its anomaly database. The time required to perform these tasks provides a window of vulnerability to DoD computer systems. Further, because of the current maximum size of an Internet Protocol-based message, the database would have to be able to maintain 25665535 possible signature combinations. In order to tighten this response cycle within storage constraints, …

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Unified Behavior Framework For Reactive Robot Control In Real-Time Systems, Brian G. Woolley Mar 2007

Unified Behavior Framework For Reactive Robot Control In Real-Time Systems, Brian G. Woolley

Theses and Dissertations

Endeavors in mobile robotics focus on developing autonomous vehicles that operate in dynamic and uncertain environments. By reducing the need for human-in- the-loop control, unmanned vehicles are utilized to achieve tasks considered dull or dangerous by humans. Because unexpected latency can adversely affect the quality of an autonomous system's operations, which in turn can affect lives and property in the real-world, their ability to detect and handle external events is paramount to providing safe and dependable operation. Behavior-based systems form the basis of autonomous control for many robots. This thesis presents the unified behavior framework, a new and novel approach …

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On-Demand Key Distribution For Mobile Ad-Hoc Networks, Daniel F. Graham Mar 2007

On-Demand Key Distribution For Mobile Ad-Hoc Networks, Daniel F. Graham

Theses and Dissertations

Mobile ad-hoc networks offer dynamic portable communication with little or no infrastructure. While this has many benefits, there are additional shortcomings specific to wireless communication that must be addressed. This research proposes gossip-based on-demand key distribution as a means to provide data encryption for mobile ad-hoc networks. This technique uses message keys to avoid encrypting and decrypting a message at every node. Other optimizations used include secure channel caching and joint rekey messages. The use of gossip makes the scheme robust to node failure. Experimental results show only a 15% increase in end-to-end delay with a node failure rate of …

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Software Protection Against Reverse Engineering Tools, Joshua A. Benson Mar 2007

Software Protection Against Reverse Engineering Tools, Joshua A. Benson

Theses and Dissertations

Advances in technology have led to the use of simple to use automated debugging tools which can be extremely helpful in troubleshooting problems in code. However, a malicious attacker can use these same tools. Securely designing software and keeping it secure has become extremely difficult. These same easy to use debuggers can be used to bypass security built into software. While the detection of an altered executable file is possible, it is not as easy to prevent alteration in the first place. One way to prevent alteration is through code obfuscation or hiding the true function of software so as …

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Performance Evaluation Of Ad Hoc Routing In A Swarm Of Autonomous Aerial Vehicles, Matthew T. Hyland Mar 2007

Performance Evaluation Of Ad Hoc Routing In A Swarm Of Autonomous Aerial Vehicles, Matthew T. Hyland

Theses and Dissertations

This thesis investigates the performance of three mobile ad hoc routing protocols in the context of a swarm of autonomous unmanned aerial vehicles (UAVs). It is proposed that a wireless network of nodes having an average of 5.1774 log n neighbors, where n is the total number of nodes in the network, has a high probability of having no partitions. By decreasing transmission range while ensuring network connectivity, and implementing multi-hop routing between nodes, spatial multiplexing is exploited whereby multiple pairs of nodes simultaneously transmit on the same channel. The proposal is evaluated using the Greedy Perimeter Stateless Routing (GPSR), …

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Analysis Of Routing Worm Infection Rates On An Ipv4 Network, James Gorsuch Mar 2007

Analysis Of Routing Worm Infection Rates On An Ipv4 Network, James Gorsuch

Theses and Dissertations

Malicious logic, specifically worms, has caused monetary expenditure problems to network users in the past. Worms, like Slammer and Code Red, have infected thousands of systems and brought the Internet to a standstill. This research examines the ability of the original Slammer worm, the Slammer based routing worm proposed by Zou et al, and a new Single Slash Eight (SSE) routing worm proposed by this research to infect vulnerable systems within a given address space. This research investigates the Slammer worm's ability to generate a uniform random IP addresses in a given address space. Finally, a comparison of the speed …

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Recommendations For A Standardized Program Management Office (Pmo) Time Compliance Network Order (Tcno) Patching Process, Michael Czumak Iii Mar 2007

Recommendations For A Standardized Program Management Office (Pmo) Time Compliance Network Order (Tcno) Patching Process, Michael Czumak Iii

Theses and Dissertations

Network security is a paramount concern for organizations utilizing computer technology, and the Air Force is no exception. Network software vulnerability patching is a critical determinant of network security. The Air Force deploys these patches as Time Compliance Network Orders (TCNOs), which together with associated processes and enforced timelines ensure network compliance. While the majority of the network assets affected by this process are Air Force owned and operated, a large number are maintained by external entities known as Program Management Offices (PMOs). Although these externally controlled systems provide a service to the Air Force and reside on its network, …

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Towards The Development Of A Defensive Cyber Damage And Mission Impact Methodology, Larry W. Fortson Jr. Mar 2007

Towards The Development Of A Defensive Cyber Damage And Mission Impact Methodology, Larry W. Fortson Jr.

Theses and Dissertations

The purpose of this research is to establish a conceptual methodological framework that will facilitate effective cyber damage and mission impact assessment and reporting following a cyber-based information incidents. Joint and service guidance requires mission impact reporting, but current efforts to implement such reporting have proven ineffective. This research seeks to understand the impediments existing in the current implementation and to propose an improved methodology. The research employed a hybrid historical analysis and case study methodology for data collection through extensive literature review, examination of existing case study research and interviews with Air Force members and civilian personnel employed as …

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Multi-Robot Fastslam For Large Domains, Choyong G. Koperski Mar 2007

Multi-Robot Fastslam For Large Domains, Choyong G. Koperski

Theses and Dissertations

For a robot to build a map of its surrounding area, it must have accurate position information within the area, and to obtain accurate position information within the area, the robot needs to have an accurate map of the area. This circular problem is the Simultaneous Localization and Mapping (SLAM) problem. An efficient algorithm to solve it is FastSLAM, which is based on the Rao-Blackwellized particle filter. FastSLAM solves the SLAM problem for single-robot mapping using particles to represent the posterior of the robot pose and the map. Each particle of the filter possesses its own global map which is …

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Stochastic Estimation And Control Of Queues Within A Computer Network, Nathan C. Stuckey Mar 2007

Stochastic Estimation And Control Of Queues Within A Computer Network, Nathan C. Stuckey

Theses and Dissertations

An extended Kalman filter is used to estimate size and packet arrival rate of network queues. These estimates are used by a LQG steady state linear perturbation PI controller to regulate queue size within a computer network. This paper presents the derivation of the transient queue behavior for a system with Poisson traffic and exponential service times. This result is then validated for ideal traffic using a network simulated in OPNET. A more complex OPNET model is then used to test the adequacy of the transient queue size model when non-Poisson traffic is combined. The extended Kalman filter theory is …

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Live Surface, Christopher J. Armstrong Feb 2007

Live Surface, Christopher J. Armstrong

Theses and Dissertations

Live Surface allows users to segment and render complex surfaces from 3D image volumes at interactive (sub-second) rates using a novel, Cascading Graph Cut (CGC). Live Surface consists of two phases. (1) Preprocessing for generation of a complete 3D watershed hierarchy followed by tracking of all catchment basin surfaces. (2) User interaction in which, with each mouse movement, the 3D object is selected and rendered in real time. Real-time segmentation is ccomplished by cascading through the 3D watershed hierarchy from the top, applying graph cut successively at each level only to catchment basins bordering the segmented surface from the previous …

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Feature-Based Mini Unmanned Air Vehicle Video Euclidean Stabilization With Local Mosaics, Damon Dyck Gerhardt Feb 2007

Feature-Based Mini Unmanned Air Vehicle Video Euclidean Stabilization With Local Mosaics, Damon Dyck Gerhardt

Theses and Dissertations

Video acquired using a camera mounted on a mini Unmanned Air Vehicle (mUAV) may be very helpful in Wilderness Search and Rescue and many other applications but is commonly plagued with limited spatial and temporal field of views, distractive jittery motions, disorienting rotations, and noisy and distorted images. These problems collectively make it very difficult for human viewers to identify objects of interest as well as infer correct orientations throughout the video. In order to expand the temporal and spatial field of view, stabilize, and better orient users of noisy and distorted mUAV video, a method is proposed of estimating …

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System For Collision Detection Between Deformable Models Built On Axis Aligned Bounding Boxes And Gpu Based Culling, David Owen Tuft Jan 2007

System For Collision Detection Between Deformable Models Built On Axis Aligned Bounding Boxes And Gpu Based Culling, David Owen Tuft

Theses and Dissertations

Collision detection between deforming models is a difficult problem for collision detection systems to handle. This problem is even more difficult when deformations are unconstrained, objects are in close proximity to one another, and when the entity count is high. We propose a method to perform collision detection between multiple deforming objects with unconstrained deformations that will give good results in close proximities. Currently no systems exist that achieve good performance on both unconstrained triangle level deformations and deformations that preserve edge connectivity. We propose a new system built as a combination of Graphics Processing Unit (GPU) based culling and …

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Eliminating Redundant And Less-Informative Rss News Articles Based On Word Similarity And A Fuzzy Equivalence Relation, Ian Garcia Jan 2007

Eliminating Redundant And Less-Informative Rss News Articles Based On Word Similarity And A Fuzzy Equivalence Relation, Ian Garcia

Theses and Dissertations

The Internet has marked this era as the information age. There is no precedent in the amazing amount of information, especially network news, that can be accessed by Internet users these days. As a result, the problem of seeking information in online news articles is not the lack of them but being overwhelmed by them. This brings huge challenges regarding processing of online news feeds, i.e., how to determine which news article is important, how to determine the quality of each news article, and how to filter irrelevant and redundant information. In this thesis, we propose a method for filtering …

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Implicit Affinity Networks, Matthew Scott Smith Jan 2007

Implicit Affinity Networks, Matthew Scott Smith

Theses and Dissertations

Although they clearly exist, affinities among individuals are not all easily identified. Yet, they offer unique opportunities to discover new social networks, strengthen ties among individuals, and provide recommendations. We propose the idea of Implicit Affinity Networks (IANs) to build, visualize, and track affinities among groups of individuals. IANs are simple, interactive graphical representations that users may navigate to uncover interesting patterns. This thesis describes a system supporting the construction of IANs and evaluates it in the context of family history and online communities.

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Skuery: Manipulation Of S-Expressions Using Xquery Techniques, Kevin Burke Tew Jan 2007

Skuery: Manipulation Of S-Expressions Using Xquery Techniques, Kevin Burke Tew

Theses and Dissertations

Data query operations inside programming languages presently perform their functions through the use of domain-specific, declarative expressions and by way of course-grain, API library calls. These methods of operation are practiced by relational databases as well as semistructured XML data stores. Layers of translation, which are necessary to transform data and instructions from the domain of programming languages to data query systems, negtatively effect the performance of data query operations. Skuery resolves this impedance by adopting XML as a native data type with a native representation (SXML). Likewise, query operations are defined in a general purpose programming language (Scheme in …

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A Browser-Side Solution For Detection And Prevention Of Cross-Site Request Forgery Attacks, Mary C. Henthorn Jan 2007

A Browser-Side Solution For Detection And Prevention Of Cross-Site Request Forgery Attacks, Mary C. Henthorn

Theses and Dissertations

The security of web-based applications concerns everyone who conducts business online. Cross-site request forgeries (CSRF) subject users, as well as applications, to attack. Cloaked by the standardized request and response interchange between browsers and web-based applications, an attacker can employ the browser as an agent to slip data into the transaction. CSRF exploits ride on session authentication and authorization, stealthily bypassing the security measures intended to form bonds of trust between the user and the application. Until CSRF protection is incorporated in all web-based applications, wary users may look for client-side protection. This thesis offers an original Firefox browser extension …

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Off-The-Record Secure Chat Room Via Public Im Services, Jiang Bian Jan 2007

Off-The-Record Secure Chat Room Via Public Im Services, Jiang Bian

Theses and Dissertations

This thesis proposes a solution into the implementation of on-line chat-room environments that ensures the privacy protection of such services and provides an off-the-record feature. Instant Messaging (IM) is becoming an integral part of social as well as business life. The main concern with IM systems is that the information being transmitted is easily accessible. Some protection could be achieved with the use of a secure tunneling (i.e. VPN etc.). Nevertheless, even the use of VPN-like technologies does not provide end-to-end secrecy. Off-the-record (OTR), designed by Borisov. N et al. is a protocol which enables IM users to have private …

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Supporting Data-Intensive Wireless Sensor Applications Using Smart Data Fragmentation And Buffer Management, Mbonisi Masilela Jan 2007

Supporting Data-Intensive Wireless Sensor Applications Using Smart Data Fragmentation And Buffer Management, Mbonisi Masilela

Theses and Dissertations

Recent advances in low power device technology have led to the development of smaller powerful sensors geared for use in Wireless Sensor Networks. Some of these sensors are capable of producing large data packets in a single reading. This becomes a challenging problem given the constraints imposed by current MAC and Transport Layer implementations since a single data packet can exceed the MTU of the protocol stack. Little has been done in the way of addressing this issue in Wireless Sensor Networks. This paper proposes a novel solution to this issue. Proposed is a Lightweight Data Transportation Protocol that uses …

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An Environmental Complexity Analysis For Robot-Environment System Design, Gang Yang Jan 2007

An Environmental Complexity Analysis For Robot-Environment System Design, Gang Yang

Theses and Dissertations

Recently, researchers have begun to investigate intelligent environments for robot applications. In this work, a robot and its work environment can be considered to be an integrated system. Currently, such robot-environment systems are designed on an ad-hoc basis, with the final performance of the system greatly dependent on the experience and preferences of the designer. This dissertation investigates a way to improve on this situation by looking at the complexity of an environment from the perspective of a robot. The objective of this research is to develop a method to evaluate environmental complexity and then use this information to help …

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Mining Frequent Patterns From Sequences: Theory, Algorithm, Implementation, And Performance, Markus Petteri Turkia Jan 2007

Mining Frequent Patterns From Sequences: Theory, Algorithm, Implementation, And Performance, Markus Petteri Turkia

Theses and Dissertations

Mining frequent patterns from sequences is an important data mining problem which has direct applications in many areas. In this thesis, we make three contributions to the state-of-the-art of the sequential frequent pattern mining. First of all, we propose a fast pattern-growth mining algorithm using a novel sequence database representation called First-Occurrence Linked WAP-tree (FLWAP-tree). The pattern-growth mining algorithm using the Pre-Order Linked WAP-tree (PLWAP-tree) was reported in the literature to be faster than other algorithms. We show that our pattern-growth using our FLWAP-tree outperforms the PLWAP-tree mining significantly and consistently. Secondly, we extend the pattern-growth algorithm with partial enumeration …

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Repurposing A Roomba: Evaluating And Training Behavior In A Simple Agent, Donald Samuel Abbott-Mccune Jan 2007

Repurposing A Roomba: Evaluating And Training Behavior In A Simple Agent, Donald Samuel Abbott-Mccune

Theses and Dissertations

Recent attempts to reprogram a Roomba to be used as a simple agent have led to interesting behavior. Observation has shown that the behavior of the Roomba is not only dependent on the precepts of the Roomba, but also relies heavily on the uncontrollable environmental conditions that the Roomba is placed in. Ultimately this makes the Roomba a great platform to test and teach aspects of artificial intelligence. This paper will show how most of the tested environmental conditions are mitigated by a learning agent that will adjust behavior dependent on the precepts that are received.

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Observational Intelligence: An Overview Of Computational Actual Entities And Their Use As Agents Of Artificial Intelligence, Brandon Scot Saunders Jan 2007

Observational Intelligence: An Overview Of Computational Actual Entities And Their Use As Agents Of Artificial Intelligence, Brandon Scot Saunders

Theses and Dissertations

This thesis' focus is on the use of Alfred North Whitehead's concept of Actual Entities as a computational tool for computer science and the introduction of a novel usage of Actual Entities as learning agents. Actual Entities are vector based agents that interact within their environment through a process called prehension. It is the combined effect of multiple Actual Entities working within a Colony of Prehending Entities that produces emergent, intelligent behavior. It is not always the case that prehension functions for desired behavior are known beforehand and frequently the functions are too complex to construct by hand. Through the …

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Screencrayons: Using Screen Captures For Annotation And Research, Trent Alan Taufer Dec 2006

Screencrayons: Using Screen Captures For Annotation And Research, Trent Alan Taufer

Theses and Dissertations

In a world full of digital information we should be able to easily collect, organize, annotate, and leverage information from many different sources. This should be easy to do and not interrupt our normal workflow. A system to support information collection and organization should be user-friendly and as unobtrusive as possible, while still allowing for flexible and intelligent annotation. It should also be able to leverage the inherent information content of a collection of annotated information. We present a system that will demonstrate how these ideas can come together to make information collection easier and more productive. The system facilitates …

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Analysis Of Near-Infrared Phase Effects On Biometric Iris Data, Brady Roos Stevenson Dec 2006

Analysis Of Near-Infrared Phase Effects On Biometric Iris Data, Brady Roos Stevenson

Theses and Dissertations

The purpose of this research is to ascertain potential iris scan data variations from near infrared waves derived from fluorescent illumination. Prior studies of iris data variances from infrared wave interference of halogen, incandescent, and sunlight with iris cameras suggest that similar changes may exist under near infrared wavelengths from fluorescent light. The concern is that the fluorescent energy emission may interfere with the near infrared detection of an iris camera. An iris camera is used to measure human eye characteristics known as biometrics. If such infrared emission is statistically significant, then it can alter the validity of the iris …

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Generating Paraphrases With Greater Variation Using Syntactic Phrases, Rebecca Diane Madsen Dec 2006

Generating Paraphrases With Greater Variation Using Syntactic Phrases, Rebecca Diane Madsen

Theses and Dissertations

Given a sentence, a paraphrase generation system produces a sentence that says the same thing but usually in a different way. The paraphrase generation problem can be formulated in the machine translation paradigm; instead of translation of English to a foreign language, the system translates an English sentence (for example) to another English sentence. Quirk et al. (2004) demonstrated this approach to generate almost 90% acceptable paraphrases. However, most of the sentences had little variation from the original input sentence. Leveraging syntactic information, this thesis project presents an approach that successfully generated more varied paraphrase sentences than the approach of …

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Contour Encoded Compression And Transmission, Christopher B. Nelson Nov 2006

Contour Encoded Compression And Transmission, Christopher B. Nelson

Theses and Dissertations

As the need for digital libraries, especially genealogical libraries, continues to rise, the need for efficient document image compression is becoming more and more apparent. In addition, because many digital library users access them from dial-up Internet connections, efficient strategies for compression and progressive transmission become essential to facilitate browsing operations. To meet this need, we developed a novel method for representing document images in a parametric form. Like other “hybrid" image compression operations, the Contour Encoded Compression and Transmission (CECAT) system first divides images into foreground and background layers. The emphasis of this thesis revolves around improving the compression …

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A Performance Evaluation Of Dynamic Transport Switching For Multi-Transport Devices, Lei Wang Nov 2006

A Performance Evaluation Of Dynamic Transport Switching For Multi-Transport Devices, Lei Wang

Theses and Dissertations

Multi-transport devices are becoming more common, but sophisticated software is needed to fully realize the advantages of these devices. In this paper, we examine the performance of dynamic transport switching, which selects the best available transport for communication between two devices. We simulate transport switching within the Quality of Transport (QoT) architecture and show that it can effectively mitigate the effects of congestion and interference for connections between two multi-transport devices. We then evaluate dynamic transport switching overhead to characterize its effect on application throughput. Based on these insights, we identify several limitations of the QoT architecture and present solutions …

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