Physical Sciences and Mathematics Commons^™

Modeling The Spread And Prevention Of Malicious Mobile Code Via Simulation Cs-2004-15, Christopher Brian Shirey

Theses and Dissertations

Malicious mobile code causes billions of dollars every year in damages, and that cost keeps increasing. Traditional signature-based anti-virus software is a reactive solution that can not detect fast spreading malicious code quickly enough to prevent widespread infection. If we hope to prevent widespread infection of future malicious mobile code, new prevention techniques must be developed that either stop a new infection completely, or at least limit the spread until signature-based anti-virus software can be updated. Simulators exist that model the spread of malicious mobile code, but none currently exists that can efficiently model host-based and network-based spread prevention techniques …

Annotation Manager: An Automated Web-Based Content Management System For Digital Libraries With Annotated Bibliographies, Frenny Thomas

Theses and Dissertations

With the expansion of the World Wide Web in the 90s, individuals (especially students) are always on a quest for information resources especially in the form of Web sites. Yet many of them are overwhelmed when faced with deciding which site will best suit their research needs. As a result, these individuals may select a resource for less than optimal reasons. To ease some of the burden, libraries have made great advances to provide a place to organize information resources. Such places are called library portals, and they typically provide a gateway to web resources by categorizing and annotating them …

Forensic Analysis Of Digital Image Tampering, Jonathan R. Sturak

Theses and Dissertations

The use of digital photography has increased over the past few years, a trend which opens the door for new and creative ways to forge images. The manipulation of images through forgery influences the perception an observer has of the depicted scene, potentially resulting in ill consequences if created with malicious intentions. This poses a need to verify the authenticity of images originating from unknown sources in absence of any prior digital watermarking or authentication technique. This research explores the holes left by existing research; specifically, the ability to detect image forgeries created using multiple image sources and specialized methods …

Analysis Of Hostile Network Reconnaissance To Anticipate And Mitigate Network Attacks, Luis Angel Rivera

Theses and Dissertations

Network security systems today such as current intrusion detection systems, intrusion prevention systems and firewalls are good at reacting to attacks as they occur or shortly after they occur. Current security systems lack the ability to identify and detect the activity that usually precedes an attack. This activity is known as network reconnaissance. In this thesis we have developed a technique that can assist current security systems to detect hostile network reconnaissance to anticipate and mitigate network attacks.

On The Use Of Randomness In Computing To Perform Intelligent Tasks, Ryan Scott Regensburger

Theses and Dissertations

The study of Artificial Intelligence attempts to simulate the processes of human intelligence in a set of computable algorithms. The purpose of Random Algorithms in this field is to provide a best-guess approach at identifying the unknown. In this thesis, research shows that random algorithms are able to break down many intelligent processes into a set of solvable problems. For example, solving puzzles and playing games involve the same estimating ability shown in standard problems such as the Coupon Collector problem or the Monty Hall problem. This thesis shows Random Algorithmic applications in two overlapping categories of intelligent behavior: Pattern …

Target-Dominant Chinese-English Machine Translation, Dan Su

Theses and Dissertations

Information exchange is increasing rapidly with the advent of globalization. As the language spoken by the most people in today's world, Chinese will play an important role in information exchange in the future. Therefore, we need an efficient and practical means to access the increasingly large volume of Chinese data. This thesis describes a target-dominant Chinese-English machine translation system, which can translate a given Chinese news sentence into English. We conjecture that we can improve the state of the art of MT using a TDMT approach. This system has participated in the NIST (National Institute of Standards and Technology) 2004 …

Automating The Extraction Of Domain-Specific Information From The Web-A Case Study For The Genealogical Domain, Troy L. Walker

Theses and Dissertations

Current ways of finding genealogical information within the millions of pages on the Web are inadequate. In an effort to help genealogical researchers find desired information more quickly, we have developed GeneTIQS, a Genealogy Target-based Information Query System. GeneTIQS builds on ontology-based methods of data extraction to allow database-style queries on the Web. This thesis makes two main contributions to GeneTIQS. (1) It builds a framework to do generic ontology-based data extraction. (2) It develops a hybrid record separator based on Vector Space Modeling that uses both formatting clues and data clues to split pages into component records. The record …

Does The Halting Necessary For Hardware Trace Collection Inordinately Perturb The Results?, Myles G. Watson

Theses and Dissertations

Processor address traces are invaluable for characterizing workloads and testing proposed memory hierarchies. Long traces are needed to exercise modern cache designs and produce meaningful results, but are difficult to collect with hardware monitors because microprocessors access memory too frequently for disks or other large storage to keep up. The small, fast buffers of the monitors fill quickly; in order to obtain long contiguous traces, the processor must be stopped while the buffer is emptied. This halting may perturb the traces collected, but this cannot be measured directly, since long uninterrupted traces cannot be collected. We make the case that …

Real-Time Image Enhancement Using Texture Synthesis, Matthew J. Sorensen

Theses and Dissertations

This thesis presents an approach to real-time image enhancement using texture synthesis. Traditional image enhancement techniques are typically time consuming, lack realistic detail, or do not scale well for large magnification factors.

Real-time Enhancement using Texture Synthesis (RETS) combines interpolation, classification, and patch-based texture synthesis to enhance low-resolution imagery, particularly aerial imagery. RETS uses as input a low-resolution source image and several high-resolution sample textures. The output of RETS is a high-resolution image with the structure of the source image, but with detail consistent with the high-resolution sample textures. We show that RETS can enhance large amounts of imagery in …

Improved Signal Integrity In Ieee 1149.1 Boundary Scan Designs, Efren De Jesus Rangel Taboada

Theses and Dissertations

This work is an analysis of solutions to problems derived from inherent timing and signal integrity issues in the use and application of the IEEE 1149.1 Standard at the board level in conjunction with its test system. Setup or hold times violations may occur in a boundary scan chain using IEEE 1149.1 compliant devices. A practical study of the TDI-TDO scan data path has been conducted to show where problems may arise in relationship to a particular board topology and test system. This work points to differences between passing and failing scan path tests for problem characterization. Serial data flow …

Disk Based Model Checking, Tonglaga Bao

Theses and Dissertations

Disk based model checking does not receive much attention in the model checking field becasue of its costly time overhead. In this thesis, we present a new disk based algorithm that can get close to or faster verification speed than a RAM based algorithm that has enough memory to complete its verification. This algorithm also outperforms Stern and Dill's original disk based algorithm. The algorithm partitions the state space to several files, and swaps files into and out of memory during verification. Compared with the RAM only algorithm, the new algoritm reduces hash table insertion time by reducing the cost …

Vision-Based Human Directed Robot Guidance, Richard B. Arthur

Theses and Dissertations

This paper describes methods to track a user-defined point in the vision of a robot as it drives forward. This tracking allows a robot to keep itself directed at that point while driving so that it can get to that user-defined point. I develop and present two new multi-scale algorithms for tracking arbitrary points between two frames of video, as well as through a video sequence. The multi-scale algorithms do not use the traditional pyramid image, but instead use a data structure called an integral image (also known as a summed area table). The first algorithm uses edge-detection to track …

Network-Layer Selective Security, Casey T. Deccio

Theses and Dissertations

The Internet and other large computer networks have become an integral part of numerous daily processes. Security at the network layer is necessary to maintain infrastructure survivability in the case of cyber attacks aimed at routing protocols. In order to minimize undesired overhead associated with added security at this level, the notion of selective security is proposed. This thesis identifies elements in network topologies that are most important to the survivability of the network. The results show that the strategic placement of network security at critical elements will improve overall network survivability without the necessity of universal deployment.

Pattern Search Ranking And Selection Algorithms For Mixed-Variable Optimization Of Stochastic Systems, Todd A. Sriver

Theses and Dissertations

A new class of algorithms is introduced and analyzed for bound and linearly constrained optimization problems with stochastic objective functions and a mixture of design variable types. The generalized pattern search (GPS) class of algorithms is extended to a new problem setting in which objective function evaluations require sampling from a model of a stochastic system. The approach combines GPS with ranking and selection (R&S) statistical procedures to select new iterates. The derivative-free algorithms require only black-box simulation responses and are applicable over domains with mixed variables (continuous, discrete numeric, and discrete categorical) to include bound and linear constraints on …

Visual Unified Modeling Language For The Composition Of Scenarios In Modeling And Simulation Systems, Daniel E. Swayne

Theses and Dissertations

The Department of Defense uses modeling and simulation systems in many various roles, from research and training to modeling likely outcomes of command decisions. Simulation systems have been increasing in complexity with the increased capability of low-cost computer systems to support these DOD requirements. The demand for scenarios is also increasing, but the complexity of the simulation systems has caused a bottleneck in scenario development due to the limited number of individuals with knowledge of the arcane simulator languages in which these scenarios are written. This research combines the results of previous AFIT efforts in visual modeling languages to create …

An Ecological Display For Robot Teleoperation, Robert W. Ricks

Theses and Dissertations

This thesis presents an interface for effectively teleoperating robots that combines an ecological display of range and video information with quickening based on dead-reckoning prediction. This display is built by viewing range and video information from a virtual camera trailing the robot. This is rendered in 3-D by using standard hardware acceleration and 3-D graphics software. Our studies demonstrate that this interface improves performance for most people, including those that do not have much previous experience with robotics. These studies involved 32 test subjects in a simulated environment and 8 in the real world. Subjects were required to drive the …

A Qualitative Method For Dynamic Transport Selection In Heterogeneous Wireless Environments, Heidi R. Duffin

Theses and Dissertations

Computing devices are commonly equipped with multiple transport technologies such as IrDA, Bluetooth and WiFi. Transport switching technologies, such as Quality of Transport (QoT), take advantage of this heterogeneity to keep network sessions active as users move in and out of range of various transports or as the networking environment changes. During an active session, the goal is to keep the device connected over the best transport currently available. To accomplish that, this thesis introduces a two-phase decision making protocol. In phase one, intra-device prioritization, users indicate the relative importance of criteria such as speed, power, service charge, or signal …

Preserving Trust Across Multiple Sessions In Open Systems, Fuk-Wing Thomas Chan

Theses and Dissertations

Trust negotiation, a new authentication paradigm, enables strangers on the Internet to establish trust through the gradual disclosure of digital credentials and access control policies. Previous research in trust negotiation does not address issues in preserving trust across multiple sessions. This thesis discusses issues in preserving trust between parties who were previously considered strangers. It also describes the design and implementation of trust preservation in TrustBuilder, a prototype trust negotiation system. Preserving trust information can reduce the frequency and cost of renegotiation. A scenario is presented that demonstrates that a server supporting trust preservation can recoup the cost of the …

Grouping Search-Engine Returned Citations For Person-Name Queries, Reema Al-Kamha

Theses and Dissertations

In this thesis we present a technique to group search-engine returned citations for person-name queries, such that the search-engine returned citations in each group belong to the same person. To group the returned citations we use a multi-faceted approach that considers evidence from three facets: (1) attributes, (2) links, and (3) page similarity. For each facet we generate a confidence matrix. Then we construct a final confidence matrix for all facets. Using a threshold, we apply a grouping algorithm on the final confidence matrix. The output is a group of search-engine returned citations, such that the citations in each group …

Reduced Index Sparse Representation In A Parallel Environment, Pedro Alfonso Escallon

Theses and Dissertations

Sparse-matrix/dense-vector multiplication algorithms are not as highly developed as algorithms for dense matrices. Dense matrix multiplication algorithms have been made efficient by exploiting data locality, parallelism, pipelining, and other types of optimization. Sparse matrix algorithms, on the other hand, encounter low or no data locality, indirect addressing, and no easy way to exploit parallelism. In an effort to achieve savings in storage and computational time, the topic of sparse matrix representation is often revisited. The first contribution of this thesis is the introduction of a new representation for sparse matrices. This representation is called here the Reduced Index Sparse (RIS) …

Improving Tcp Performance By Estimating Errors In A Long Delay, High Error Rate Environment, Stephanie E. Carroll

Theses and Dissertations

Interest in finding methods of improving TCP performance over satellite and wireless networks is high. This has been an active area of research within the networking community. This research develops an algorithm, CETEN-R for TCP to determine if a particular packet is lost due to congestion or corruption and react accordingly. An analysis of the performance of CETEN-R under a variety of conditions is studied and then compared to TCP Reno and TCP New Reno. When delay is high and the error rate is high CETEN-R showed a 77.5% increase in goodput over TCP New Reno and a 33.8% increase …

Load Balancing Parallel Explicit State Model Checking, Rahul Kumar

Theses and Dissertations

This research first identifies some of the key concerns about the techniques and algorithms developed for distributed and parallel model checking; specifically, the inherent problem with load balancing and large queue sizes resultant in a static partition algorithm. This research then presents a load balancing algorithm to improve the run time performance in distributed model checking, reduce maximum queue size, and reduce the number of states expanded before error discovery. The load balancing algorithm is based on Generalized Dimension Exchange (GDE). This research presents an empirical analysis of the GDE based load balancing algorithm on three different supercomputing architectures---distributed memory …

Solving Large Mdps Quickly With Partitioned Value Iteration, David Wingate

Theses and Dissertations

Value iteration is not typically considered a viable algorithm for solving large-scale MDPs because it converges too slowly. However, its performance can be dramatically improved by eliminating redundant or useless backups, and by backing up states in the right order. We present several methods designed to help structure value dependency, and present a systematic study of companion prioritization techniques which focus computation in useful regions of the state space. In order to scale to solve ever larger problems, we evaluate all enhancements and methods in the context of parallelizability. Using the enhancements, we discover that in many instances the limiting …

On The Effects Of Device Mobility Upon Resource-Sharing In A Simulated Wireless Grid Network, Arris Ray

Theses and Dissertations

The primary aim of modern computer networks is to permit simplified sharing of resources (e.g., files and data) or to provide access to remote resources (e.g., printers or remote file-systems). Grid networks aim to provide a more sophisticated framework for securely sharing, selecting and/or aggregating a wide-variety of remote resources, whether logical (e.g., files and data) or physical (e.g., remote sensors, processing power or disk storage space). Provided that circuit design continues to improve at the relatively steady pace that it has for the past decade, in addition to standard desktop systems, miniature and mobile devices will soon become substantially …

Quantifying Software Maintainability On Re-Engineered Translation Of Fortran To C++ Code, Zane Grey Tomlinson Jr.

Theses and Dissertations

Due to the expanding existence of old software, legacy systems, and obsolete platforms with many industries, software re-engineering has become a widespread methodology that assists engineers and software practitioners with translating inflexible, unsupportable legacy software into maintainable software. Many companies today are investing in a variety of re-engineering techniques such as translation of source code to new code structures and target platforms to ensure future software maintenance can be performed in an efficient and effective manner. With sound re-engineering principles, the application of these techniques leverage the knowledge and previous engineering endeavors to mitigate risks and provide adequate performance to …

Mool: An Object-Oriented Programming Language With Generics And Modules., María Lucía Barrón Estrada

Theses and Dissertations

Modern object-oriented languages like Java and C# do not support parametric polymorphism and do not have a traditional module system to allow the development of large systems. They overload the class mechanism with several tasks and they use packages and namespaces to organize clusters of classes providing weak control for accessing members. Other languages that support generic programming and objects do not have a simple object model to support object-oriented features. In this thesis the language MOOL is presented. MOOL is a class-based object-oriented language that supports modular programming and genericity. The main goal in the design of MOOL was …

Web-Based Trend Analysis Of Rocket Data Using Xml, Mark Randall Gibson

Theses and Dissertations

This paper will discuss and prove the feasibility of using XML to transfer, compare, and view data created during automated testing of black boxes; stored both in simple text format and relational database format. This system arises from the need for the reliability department to review the test data from the flight hardware at all testing locations. For the purposes of this paper we will refer to this system as the "Test Data Retrieval System" (TDRS). This data review is being done to determine if there are any negative trends in the hardware that may be surfacing. This data resides …

Solving Combinatorial Optimization Problems Using A New Algorithm Based On Gravitational Attraction, Barry Lynn Webster

Theses and Dissertations

This dissertation represents the culmination of research into the development of a new algorithm for locating optimal solutions to difficult problems. This new algorithm is founded upon one of the most basic concepts in nature - so basic that it is in fact one of the four primary forces in physics: gravity. It is called the Gravitational Emulation Local Search algorithm, or GELS. Four variants of the algorithm were developed, representing combinations of two basic methods of operation and two modes of search space exploration. Following development, a series of experiments were conducted to assess the capabilities of this new …

Learning States For Detecting Anomalies In Time Series, Stan Weidner Salvador

Theses and Dissertations

The normal operation of a device can be characterized in different operational states. To identify these states, we introduce a segmentation algorithm called Gecko that can determine a reasonable number of segments using our proposed L method. We then use the RIPPER classification algorithm to describe these states in logical rules. Finally, transitional logic between the states is added to create a finite state automation. Multiple time series data may be used for training, by merging several time series into a single representative time series using dynamic time warping. Our empirical results, on data obtained from the NASA shuttle program, …

Responding To Policies At Runtime In Trustbuilder, Bryan J. Smith

Theses and Dissertations

Automated trust negotiation is the process of establishing trust between entities with no prior relationship through the iterative disclosure of digital credentials. One approach to negotiating trust is for the participants to exchange access control policies to inform each other of the requirements for establishing trust. When a policy is received at runtime, a compliance checker determines which credentials satisfy the policy so they can be disclosed. In situations where several sets of credentials satisfy a policy and some of the credentials are sensitive, a compliance checker that generates all the sets is necessary to insure that the negotiation succeeds …