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Theses and Dissertations

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Articles 1951 - 1980 of 2733

Full-Text Articles in Computer Sciences

Algorithms For White-Box Obfuscation Using Randomized Subcircuit Selection And Replacement, Kenneth E. Norman Mar 2008

Algorithms For White-Box Obfuscation Using Randomized Subcircuit Selection And Replacement, Kenneth E. Norman

Theses and Dissertations

Software protection remains an active research area with the goal of preventing adversarial software exploitation such as reverse engineering, tampering, and piracy. Heuristic obfuscation techniques lack strong theoretical underpinnings while current theoretical research highlights the impossibility of creating general, efficient, and information theoretically secure obfuscators. In this research, we consider a bridge between these two worlds by examining obfuscators based on the Random Program Model (RPM). Such a model envisions the use of program encryption techniques which change the black-box (semantic) and white-box (structural) representations of underlying programs. In this thesis we explore the possibilities for white-box transformation. Under an …

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Signal Processing Design Of Low Probability Of Intercept Waveforms, Nathaniel C. Liefer Mar 2008

Signal Processing Design Of Low Probability Of Intercept Waveforms, Nathaniel C. Liefer

Theses and Dissertations

This thesis investigates a modification to Differential Phase Shift Keyed (DPSK) modulation to create a Low Probability of Interception/Exploitation (LPI/LPE) communications signal. A pseudorandom timing offset is applied to each symbol in the communications stream to intentionally create intersymbol interference (ISI) that hinders accurate symbol estimation and bit sequence recovery by a non-cooperative receiver. Two cooperative receiver strategies are proposed to mitigate the ISI due to symbol timing offset: a modified minimum Mean Square Error (MMSE) equalization algorithm and a multiplexed bank of equalizer filters determined by an adaptive Least Mean Square (LMS) algorithm. Both cooperative receivers require some knowledge …

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Identification Of Command And Control Information Requirements For The Cyberspace Domain, Brian D. Aschenbrenner Mar 2008

Identification Of Command And Control Information Requirements For The Cyberspace Domain, Brian D. Aschenbrenner

Theses and Dissertations

The purpose of this research was to develop an information requirements analysis method that would provide the Director of Cyberspace Forces with the information required to support effective command and control of cyberspace. This research investigates the role of information in command and control, information in the traditional war fighting domains, cyberspace as a war fighting domain, and various methods of determining information requirements of organizations. This research produced an information requirements analysis method that is suitable for identifying the command and control information requirements of the Director of Cyberspace Forces.

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Cyber Flag: A Realistic Cyberspace Training Construct, Andrew P. Hansen Mar 2008

Cyber Flag: A Realistic Cyberspace Training Construct, Andrew P. Hansen

Theses and Dissertations

As is well understood, the rapidly unfolding challenges of cyberspace is a fundamental warfare paradigm shift revolutionizing the way future wars will be fought and won. A significant test for the Air Force (indeed any organization with a credible presence in cyberspace) will be providing a realistic training environment that fully meets this challenge. Why create another Flag level exercise? Realistic training (that which is effective, comprehensive and coordinated) is crucial to success in time of war. Red Flag provides dominant training within the air domain and now with the evolution of cyberspace, a comprehensive training environment is necessary to …

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Simulation And Visualization Of Environments With Multidimensional Time, Luther A. Tychonievich Jan 2008

Simulation And Visualization Of Environments With Multidimensional Time, Luther A. Tychonievich

Theses and Dissertations

This work introduces the notion of computational hypertime, or the simulation and visualization of hypothetical environments possessing multidimensional time. An overview of hypertime is provided,including an intuitive visualization paradigm and a discussion of the failure of common simulation techniques when extended to include multidimensional time. A condition for differential equations describing hypertime motion to be amenable to standard time-iterative simulation techniques is provided,but is not satisfied by any known model of physics. An alternate simulation algorithm involving iterative refinement of entire equations of motion is presented,with an example implementation to solve elastic collisions in hypertime. An artificial intelligence algorithm for …

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Wireless Authentication Using Remote Passwords, Andrew S. Harding Jan 2008

Wireless Authentication Using Remote Passwords, Andrew S. Harding

Theses and Dissertations

Current authentication methods for wireless networks are difficult to maintain. They often rely on globally shared secrets or heavyweight public-key infrastructure. Wireless Authentication using Remote Passwords (WARP) mitigates authentication woes by providing usable mechanisms for both administrators and end-users. Administrators grant access by simply adding users' personal messaging identifiers (e.g., email addresses, IM handles, cell phone numbers) to an access control list. There is no need to store passwords or other account information. Users simply prove ownership of their authorized identifier to obtain wireless access.

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Robot Controller Architecture: Layered Mode Selection Logic With Fuzzy Sensor Fusion Network, Traig E.B. Born Jan 2008

Robot Controller Architecture: Layered Mode Selection Logic With Fuzzy Sensor Fusion Network, Traig E.B. Born

Theses and Dissertations

A behavior based robot controller was implemented using Layered Mode Selection Logic as a behavior coordination mechanism and a Fuzzy Sensor Fusion Network to provide perception. A series of collision experiments were conducted to create a Fuzzy Sensor Fusion Network capable of detecting collisions using acceleration readings from wheel encoders. An obstacle avoidance behavior was created, and it was demonstrated that the robot could be constrained by movable obstacles. The avoidance behavior was modified to create an obstacle manipulation behavior. This behavior allowed the robot to escape when enclosed by movable obstacles. The fuzzy sensor fusion network was enhanced to …

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Network Security In Two-Year Colleges, Tamya Jean Stallings Jan 2008

Network Security In Two-Year Colleges, Tamya Jean Stallings

Theses and Dissertations

Network security has become a growing challenge in industry and education. With the increase of viruses, spam, hackers, and identity theft, organizations are beginning to look at areas to improve the protection of their Information Technology structure. Higher Education has the highest vulnerability to network security threats especially the two-year institutions. Two-year institutions are known for open access admission. Open labs, limited staff and resources hinder security measures for these institutions. This thesis focuses on the two-year institution delving into the Information Technology Departments and how security is handled. What challenges have these institutions faced trying to protect data and …

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Networks And Network Security, Michael Kuralt Jan 2008

Networks And Network Security, Michael Kuralt

Theses and Dissertations

In a world of ever-increasing security threats, companies have the difficult task of securing their networks from attack. One of the largest threats to a company is the users on its network. By educating its network administrators and employees about network threats, a company can lower its vulnerability to network attacks. Individual users also can benefit from understanding networks and network security by learning how to keep their computer and their information safe. Companies and users can stay safe by understanding how a network functions, what threats exist on the Internet, how to prevent and deal with attacks, and how …

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A Unified Framework For Solving Multiagent Task Assignment Problems, Kevin Cousin Dec 2007

A Unified Framework For Solving Multiagent Task Assignment Problems, Kevin Cousin

Theses and Dissertations

Multiagent task assignment problem descriptors do not fully represent the complex interactions in a multiagent domain, and algorithmic solutions vary widely depending on how the domain is represented. This issue is compounded as related research fields contain descriptors that similarly describe multiagent task assignment problems, including complex domain interactions, but generally do not provide the mechanisms needed to solve the multiagent aspect of task assignment. This research presents a unified approach to representing and solving the multiagent task assignment problem for complex problem domains. Ideas central to multiagent task allocation, project scheduling, constraint satisfaction, and coalition formation are combined to …

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A Hybrid Multi-Robot Control Architecture, Daylond J. Hooper Dec 2007

A Hybrid Multi-Robot Control Architecture, Daylond J. Hooper

Theses and Dissertations

Multi-robot systems provide system redundancy and enhanced capability versus single robot systems. Implementations of these systems are varied, each with specific design approaches geared towards an application domain. Some traditional single robot control architectures have been expanded for multi-robot systems, but these expansions predominantly focus on the addition of communication capabilities. Both design approaches are application specific and limit the generalizability of the system. This work presents a redesign of a common single robot architecture in order to provide a more sophisticated multi-robot system. The single robot architecture chosen for application is the Three Layer Architecture (TLA). The primary strength …

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Web Based Resource Management For Multi-Tiered Web Applications, Bryce Daniel Ott Dec 2007

Web Based Resource Management For Multi-Tiered Web Applications, Bryce Daniel Ott

Theses and Dissertations

The currently emerging trend of building more complex web applications to solve increasingly more involved software problems has led to the the need for a more automated and practical means for deploying resources required by these advanced web applications. As web based applications become more complex and involve more developers, greater system redundancy, and a larger number of components, traditional means of resource deployment become painfully inadequate as they fail to scale sufficiently. The purpose of this research is to provide evidence that a more sound and scalable test and deployment process can be employed and that many of the …

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Route Validation Using Radio Frequency Identification, William T. Watson Dec 2007

Route Validation Using Radio Frequency Identification, William T. Watson

Theses and Dissertations

In recent years, radio frequency identification (RFID) has been proposed and implemented in a variety of applications where tracking objects, animals or people is desirable. This paper proposes a novel approach to the application of RFID technology in those applications where it is possible to validate a person or an object's passive contact with a given or arbitrary set of fixed points along a predefined route. The notable departure from the typical application of RFID technology is that in this scheme, the transponders are permanently installed while the interrogator is affixed to a person or object that travels the course. …

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Rss Management: An Rss Reader To Manage Rss Feeds That Efficiently And Effectively Pulls And Filters Feeds With Minimal Bandwidth Consumption, Brian Cooper Dec 2007

Rss Management: An Rss Reader To Manage Rss Feeds That Efficiently And Effectively Pulls And Filters Feeds With Minimal Bandwidth Consumption, Brian Cooper

Theses and Dissertations

In the early 2000s, RSS (Really Simple Syndication) was launched into cyber space and rapidly gained fame by existing as the underlying technology that fueled millions of web logs (blogs). Soon RSS feeds appeared for news, multimedia podcasting, and many other types of information on the Internet. RSS introduced a new way to syndicate information that allowed anyone interested to subscribe to published content and pull the information to an aggregator, (RSS reader application), at their discretion. RSS made it simple for people to keep up with online content without having to continuously check websites for new content. This new …

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Malicious Mobile Code Related Experiments With An Extensible Network Simulator, Attila Ondi Dec 2007

Malicious Mobile Code Related Experiments With An Extensible Network Simulator, Attila Ondi

Theses and Dissertations

The automated spread of worms such as Code-Red, SQL/Slammer, and Nimda have caused costly problems to computers connected to the Internet. Even users whose machines were not vulnerable to these threats suffered a loss of productivity and experienced great frustration as connectivity and network traffic were negatively impacted during outbreaks. Although the number of new worm attacks reported in the media seems to be declining, it is vital that researchers study the effects of malicious code on the global network to understand how to defend against future threats. The choice of system for studying the spread of worms and viruses …

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A Direct Algorithm For The K-Nearest-Neighbor Classifier Via Local Warping Of The Distance Metric, Tohkoon Neo Nov 2007

A Direct Algorithm For The K-Nearest-Neighbor Classifier Via Local Warping Of The Distance Metric, Tohkoon Neo

Theses and Dissertations

The k-nearest neighbor (k-NN) pattern classifier is a simple yet effective learner. However, it has a few drawbacks, one of which is the large model size. There are a number of algorithms that are able to condense the model size of the k-NN classifier at the expense of accuracy. Boosting is therefore desirable for increasing the accuracy of these condensed models. Unfortunately, there does not exist a boosting algorithm that works well with k-NN directly. We present a direct boosting algorithm for the k-NN classifier that creates an ensemble of models with locally modified distance weighting. An empirical study conducted …

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Supporting Flight Control For Uav-Assisted Wilderness Search And Rescue Through Human Centered Interface Design, Joseph L. Cooper Nov 2007

Supporting Flight Control For Uav-Assisted Wilderness Search And Rescue Through Human Centered Interface Design, Joseph L. Cooper

Theses and Dissertations

Inexpensive, rapidly deployable, camera-equipped Unmanned Aerial Vehicle (UAV) systems can potentially assist with a huge number of tasks. However, in many cases such as wilderness search and rescue (WiSAR), the potential users of the system may not be trained as pilots. Simple interface concepts can be used to build an interaction layer that allows an individual with minimal operator training to use the system to facilitate a search or inspection task. We describe an analysis of WiSAR as currently accomplished and show how a UAV system might fit into the existing structure. We then discuss preliminary system design efforts for …

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Intersection Algorithms Based On Geometric Intervals, Nicholas Stewart North Oct 2007

Intersection Algorithms Based On Geometric Intervals, Nicholas Stewart North

Theses and Dissertations

This thesis introduces new algorithms for solving curve/curve and ray/surface intersections. These algorithms introduce the concept of a geometric interval to extend the technique of Bézier clipping. A geometric interval is used to tightly bound a curve or surface or to contain a point on a curve or surface. Our algorithms retain the desirable characteristics of the Bézier clipping technique such as ease of implementation and the guarantee that all intersections over a given interval will be found. However, these new algorithms generally exhibit cubic convergence, improving on the observed quadratic convergence rate of Bézier clipping. This is achieved without …

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Heuristic Weighted Voting, Kristine Perry Monteith Oct 2007

Heuristic Weighted Voting, Kristine Perry Monteith

Theses and Dissertations

Selecting an effective method for combining the votes of classifiers in an ensemble can have a significant impact on the overall classification accuracy an ensemble is able to achieve. With some methods, the ensemble cannot even achieve as high a classification accuracy as the most accurate individual classifying component. To address this issue, we present the strategy of Heuristic Weighted Voting, a technique that uses heuristics to determine the confidence that a classifier has in its predictions on an instance by instance basis. Using these heuristics to weight the votes in an ensemble results in an overall average increase in …

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Limitations And Extensions Of The Wolf-Phc Algorithm, Philip R. Cook Sep 2007

Limitations And Extensions Of The Wolf-Phc Algorithm, Philip R. Cook

Theses and Dissertations

Policy Hill Climbing (PHC) is a reinforcement learning algorithm that extends Q-learning to learn probabilistic policies for multi-agent games. WoLF-PHC extends PHC with the "win or learn fast" principle. A proof that PHC will diverge in self-play when playing Shapley's game is given, and WoLF-PHC is shown empirically to diverge as well. Various WoLF-PHC based modifications were created, evaluated, and compared in an attempt to obtain convergence to the single shot Nash equilibrium when playing Shapley's game in self-play without using more information than WoLF-PHC uses. Partial Commitment WoLF-PHC (PCWoLF-PHC), which performs best on Shapley's game, is tested on other …

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Improving Neural Network Classification Training, Michael Edwin Rimer Sep 2007

Improving Neural Network Classification Training, Michael Edwin Rimer

Theses and Dissertations

The following work presents a new set of general methods for improving neural network accuracy on classification tasks, grouped under the label of classification-based methods. The central theme of these approaches is to provide problem representations and error functions that more directly improve classification accuracy than conventional learning and error functions. The CB1 algorithm attempts to maximize classification accuracy by selectively backpropagating error only on misclassified training patterns. CB2 incorporates a sliding error threshold to the CB1 algorithm, interpolating between the behavior of CB1 and standard error backpropagation as training progresses in order to avoid prematurely saturated network weights. CB3 …

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Parallelization Of Ant Colony Optimization Via Area Of Expertise Learning, Adrian A. De Freitas Sep 2007

Parallelization Of Ant Colony Optimization Via Area Of Expertise Learning, Adrian A. De Freitas

Theses and Dissertations

Ant colony optimization algorithms have long been touted as providing an effective and efficient means of generating high quality solutions to NP-hard optimization problems. Unfortunately, while the structure of the algorithm is easy to parallelize, the nature and amount of communication required for parallel execution has meant that parallel implementations developed suffer from decreased solution quality, slower runtime performance, or both. This thesis explores a new strategy for ant colony parallelization that involves Area of Expertise (AOE) learning. The AOE concept is based on the idea that individual agents tend to gain knowledge of different areas of the search space …

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Collaborative, Trust-Based Security Mechanisms For A National Utility Intranet, Gregory M. Coates Sep 2007

Collaborative, Trust-Based Security Mechanisms For A National Utility Intranet, Gregory M. Coates

Theses and Dissertations

This thesis investigates security mechanisms for utility control and protection networks using IP-based protocol interaction. It proposes flexible, cost-effective solutions in strategic locations to protect transitioning legacy and full IP-standards architectures. It also demonstrates how operational signatures can be defined to enact organizationally-unique standard operating procedures for zero failure in environments with varying levels of uncertainty and trust. The research evaluates layering encryption, authentication, traffic filtering, content checks, and event correlation mechanisms over time-critical primary and backup control/protection signaling to prevent disruption by internal and external malicious activity or errors. Finally, it shows how a regional/national implementation can protect private …

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A Framework For Analyzing And Mitigating The Vulnerabilities Of Complex Systems Via Attack And Protection Trees, Kenneth S. Edge Sep 2007

A Framework For Analyzing And Mitigating The Vulnerabilities Of Complex Systems Via Attack And Protection Trees, Kenneth S. Edge

Theses and Dissertations

Attack trees have been developed to describe processes by which malicious users attempt to exploit or break complex systems. Attack trees offer a method of decomposing, visualizing, and determining the cost or likelihood of attacks. Attack trees by themselves do not provide enough decision support to system defenders. This research develops the concept of using protection trees to offer a detailed risk analysis of a system. In addition to developing protection trees, this research improves the existing concept of attack trees and develops rule sets for the manipulation of metrics used in the security of complex systems. This research specifically …

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Multi-Objective Optimization For Speed And Stability Of A Sony Aibo Gait, Christopher A. Patterson Sep 2007

Multi-Objective Optimization For Speed And Stability Of A Sony Aibo Gait, Christopher A. Patterson

Theses and Dissertations

Locomotion is a fundamental facet of mobile robotics that many higher level aspects rely on. However, this is not a simple problem for legged robots with many degrees of freedom. For this reason, machine learning techniques have been applied to the domain. Although impressive results have been achieved, there remains a fundamental problem with using most machine learning methods. The learning algorithms usually require a large dataset which is prohibitively hard to collect on an actual robot. Further, learning in simulation has had limited success transitioning to the real world. Also, many learning algorithms optimize for a single fitness function, …

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Scaling Ant Colony Optimization With Hierarchical Reinforcement Learning Partitioning, Erik J. Dries Sep 2007

Scaling Ant Colony Optimization With Hierarchical Reinforcement Learning Partitioning, Erik J. Dries

Theses and Dissertations

This research merges the hierarchical reinforcement learning (HRL) domain and the ant colony optimization (ACO) domain. The merger produces a HRL ACO algorithm capable of generating solutions for both domains. This research also provides two specific implementations of the new algorithm: the first a modification to Dietterich's MAXQ-Q HRL algorithm, the second a hierarchical ACO algorithm. These implementations generate faster results, with little to no significant change in the quality of solutions for the tested problem domains. The application of ACO to the MAXQ-Q algorithm replaces the reinforcement learning, Q-learning and SARSA, with the modified ant colony optimization method, Ant-Q. …

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Ontology Aware Software Service Agents: Meeting Ordinary User Needs On The Semantic Web, Muhammed Jassem Al Muhammed Aug 2007

Ontology Aware Software Service Agents: Meeting Ordinary User Needs On The Semantic Web, Muhammed Jassem Al Muhammed

Theses and Dissertations

To achieve the dream of the semantic web, it must be possible for ordinary users to invoke services. It is clear that users need simple-to-invoke-and-use services. This dissertation offers an ontological approach to declaratively create services that users can invoke using free-form, natural-language-like specifications. Our approach uses task ontologies as foundational knowledge. A task ontology consists of a domain ontology and a process ontology. The domain ontology encodes domain information such as possible constraints and instances in terms of object sets, relationship sets among these object sets, and operations over values in object sets and relationship sets. The process ontology …

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The Spillable Environment: Expanding A Handheld Device's Screen Real Estate And Interactive Capabilities, Jeffrey S. Clement Aug 2007

The Spillable Environment: Expanding A Handheld Device's Screen Real Estate And Interactive Capabilities, Jeffrey S. Clement

Theses and Dissertations

Handheld devices have a limited amount of screen real estate. If a handheld device could take advantage of larger screens, it would create a more powerful user interface and environment. As time progresses, Moore's law predicts that the computational power of handheld devices will increase dramatically in the future, promoting the interaction with a larger screen. Users can then use their peripheral vision to recognize spatial relationships between objects and solve problems more easily with this integrated system. In the spillable environment, the handheld device uses a DiamondTouch Table, a large, touch-sensitive horizontal table, to enhance the viewing environment. When …

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Text Identification By Example, Daniel Joseph Preece Aug 2007

Text Identification By Example, Daniel Joseph Preece

Theses and Dissertations

The World-Wide Web contains a lot of information and reading through the web pages to collect this information is tedious, time consuming and error prone. Users need an automated solution for extracting or highlighting the data that they are interested in. Building a regular expression to match the text they are interested in will automate the process, but regular expressions are hard to create and certainly are not feasible for non-programmers to construct. Text Identification by Example (TIBE) makes it easier for end-users to harvest information from the web and other text documents. With TIBE, training text classifiers from user-selected …

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Sampling Methods In Ray-Based Global Illumination, David Cline Jul 2007

Sampling Methods In Ray-Based Global Illumination, David Cline

Theses and Dissertations

In computer graphics, algorithms that attempt to create photographic images by simulating light transport are collectively known as Global Illumination methods. The most versatile of these are based on ray tracing (following ray paths through a scene), and numerical integration using random or quasi-random sampling. While ray tracing and sampling methods in global illumination have progressed much in the last two decades, the goal of fast and accurate simulation of light transport remains elusive. This dissertation presents a number of new sampling methods that attempt to address some of the shortcomings of existing global illumination algorithms. The first part of …

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