Computer Sciences Commons^™

Development Of Advanced Algorithms To Detect, Characterize And Forecast Solar Activities, Yuan Yuan

Dissertations

Study of the solar activity is an important part of space weather research. It is facing serious challenges because of large data volume, which requires application of state-of-the-art machine learning and computer vision techniques. This dissertation targets at two essential aspects in space weather research: automatic feature detection and forecasting of eruptive events.

Feature detection includes solar filament detection and solar fibril tracing. A solar filament consists of a mass of gas suspended over the chromosphere by magnetic fields and seen as a dark, ribbon-shaped feature on the bright solar disk in Hα (Hydrogen-alpha) full-disk solar images. In this dissertation, …

Applications Of Stochastic Simulation In Two-Stage Multiple Comparisons With The Best Problem And Time Average Variance Constant Estimation, Dibyendu Chakrabarti

Dissertations

In this dissertation, we study two problems. In the first part, we consider the two-stage methods for comparing alternatives using simulation. Suppose there are a finite number of alternatives to compare, with each alternative having an unknown parameter that is the basis for comparison. The parameters are to be estimated using simulation, where the alternatives are simulated independently. We develop two-stage selection and multiple-comparison procedures for simulations under a general framework. The assumptions are that each alternative has a parameter estimation process that satisfies a random- time-change central limit theorem (CLT), and there is a weakly consistent variance estimator (WCVE) …

Active Caching For Recommender Systems, Muhammad Umar Qasim

Dissertations

Web users are often overwhelmed by the amount of information available while carrying out browsing and searching tasks. Recommender systems substantially reduce the information overload by suggesting a list of similar documents that users might find interesting. However, generating these ranked lists requires an enormous amount of resources that often results in access latency. Caching frequently accessed data has been a useful technique for reducing stress on limited resources and improving response time. Traditional passive caching techniques, where the focus is on answering queries based on temporal locality or popularity, achieve a very limited performance gain. In this dissertation, we …

Cloud Shadow Detection And Removal From Aerial Photo Mosaics Using Light Detection And Ranging (Lidar) Reflectance Images, Glover Eugene George

Dissertations

The process of creating aerial photo mosaics can be severely affected by clouds and the shadows they create. In the CZMIL project discussed in this work, the aerial survey aircraft flies below the clouds, but the shadows cast from clouds above the aircraft cause the resultant mosaic image to have sub-optimal results. Large intensity variations, caused both from the cloud shadow within a single image and the juxtaposition of areas of cloud shadow and no cloud shadow during the image stitching process, create an image that may not be as useful to the concerned research scientist. Ideally, we would like …

A Methodology To Develop A Communication Protocol For Visualizing Simulations In A Collaborative Virtual Reality Environment, Lacey Suzanne Duckworth

Dissertations

In the technology field, simulations and collaborative virtual reality environments (CVREs) are not generally combined because it is complicated to develop large scale simulations within CVREs. The complexity of combining these two technologies in order to form a better form of visualization stems from the lack of a methodology to help derive these scalable simulations. Simulations require very complex calculations that the CVRE cannot perform as it is overloaded in calculations for the maintenance and stability of the environment itself. Since the simulation cannot be held within the CVRE, the solution is to move the simulation external to the CVRE …

A Molecular Dynamics Simulation Based Principal Component Analysis Framework For Computation Of Multi-Scale Modeling Of Protein And Its Interaction With Solvent, Tao Wu

Dissertations

This dissertation presents a new computational framework for calculating the normal modes and interactions of proteins, macromolecular assemblies and surrounding solvents. The framework employs a combination of molecular dynamics simulation (MD) and principal component analysis (PCA). It enables the capture and visualization of the molecules' normal modes and interactions over time scales that are computationally challenging. It also provides a starting point for experimental and further computational studies of protein conformational changes.

A protein's function is sometimes linked to its conformational flexibility. Normal mode analysis (NMA) and various extensions of it have provided insights into the conformational fluctuations associated with …

Face Recognition Using Multiple Features In Different Color Spaces, Zhiming Liu

Dissertations

Face recognition as a particular problem of pattern recognition has been attracting substantial attention from researchers in computer vision, pattern recognition, and machine learning. The recent Face Recognition Grand Challenge (FRGC) program reveals that uncontrolled illumination conditions pose grand challenges to face recognition performance. Most of the existing face recognition methods use gray-scale face images, which have been shown insufficient to tackle these challenges. To overcome this challenging problem in face recognition, this dissertation applies multiple features derived from the color images instead of the intensity images only.

First, this dissertation presents two face recognition methods, which operate in different …

Debugging Support For Message-Passing Based Concurrent Software, Mohamed Medhat Elwakil

Dissertations

Today, multi-core processors are used in all computing aspects, including embedded systems such as mobile devices. In order for software programs to benefit from the transition to multi-core processors, the programs need to be concurrent.

Recent research shows that programs developed using the message-passing model can scale better than programs developed using the shared-memory model. However, the message-passing model is not widely adopted, partly, because of the lack of debugging tools. Debugging message-passing programs is very intricate due to their inherent nondeterministic behavior; even with the same input, a program may behave differently when executed multiple times. Bugs in message-passing …

Leach-Sm: A Protocol For Extending Wireless Sensor Network Lifetime By Management Of Spare Nodes, Bilal Abu Bakr

Dissertations

Operational lifetime of a wireless sensor network (WSN) depends on its energy resources. Significant improvement of WSN lifetime can be achieved by adding spare sensor nodes to WSN. Spares are ready to be switched on when any primary (a node that is not a spare) exhausts its energy. A spare replacing a primary becomes a primary itself.

The LEACH-SM protocol (Low-Energy Adaptive Clustering Hierarchy with Spare Management) proposed by us is a modification of the prominent LEACH protocol. LEACH extends WSN lifetime via rotation of cluster heads but allows for inefficiencies due to redundant sensing target coverage. There are two …

Active Bundles For Protecting Confidentiality Of Sensitive Data Throughout Their Lifecycle, Lotfi Ben Othmane

Dissertations

Protecting confidentiality of shared sensitive data requires satisfying conflicting needs for disseminating data and preventing unauthorized data disclosures. We propose a solution named the active bundles scheme for protecting sensitive data from their disclosures to unauthorized parties during their dissemination. The scheme protects data throughout their entire lifecycle, from data creation through their dissemination to their evaporation or apoptosis (a partial or complete self-destruction, respectively).

An active bundle packages together sensitive data, metadata, and a virtual machine (VM) specific to the bundle. Metadata contain information related to the use of data, including data access control and dissemination policies. A VM …

Stereo Matching Using A Modified Efficient Belief Propagation In A Level Set Framework, Stephen Goyer Rogers

Dissertations

Stereo matching determines correspondence between pixels in two or more images of the same scene taken from different angles; this can be handled either locally or globally. The two most common global approaches are belief propagation (BP) and graph cuts.

Efficient belief propagation (EBP), which is the most widely used BP approach, uses a multi-scale message passing strategy, an O(k) smoothness cost algorithm, and a bipartite message passing strategy to speed up the convergence of the standard BP approach. As in standard belief propagation, every pixel sends messages to and receives messages from its four neighboring pixels in EBP. Each …

Cloud Computing:Strategies For Cloud Computing Adoption, Faith Shimba

Dissertations

The advent of cloud computing in recent years has sparked an interest from different organisations, institutions and users to take advantage of web applications. This is a result of the new economic model for the Information Technology (IT) department that cloud computing promises. The model promises a shift from an organisation required to invest heavily for limited IT resources that are internally managed, to a model where the organisation can buy or rent resources that are managed by a cloud provider, and pay per use. Cloud computing also promises scalability of resources and on-demand availability of resources.

Although, the adoption …

Natural Selection On Mrna Secondary Structure And Its Correlation With Protein Functional Groups, Suresh Solaimuthu

Dissertations

Natural selection may occur at multiple levels of the biological hierarchy, including at the molecular level. It may occur on any phenotypic trait that evidences variation and that is heritable. This research uses computational methods to investigate whether the stability of the secondary structures of mRNAs has been the subject of natural selection.

The DNA sequence that codes for a particular target protein is only partially determined by that protein, since the redundancy of the genetic code permits multiple possible synonymous codons for each peptide. An RNA transcript of a DNA protein template (gene) folds back on itself through complementary …

Dnagents: Genetically Engineered Intelligent Mobile Agents, Jeremy Otho Kackley

Dissertations

Mobile agents are a useful paradigm for network coding providing many advantages and disadvantages. Unfortunately, widespread adoption of mobile agents has been hampered by the disadvantages, which could be said to outweigh the advantages. There is a variety of ongoing work to address these issues, and this is discussed. Ultimately, genetic algorithms are selected as the most interesting potential avenue. Genetic algorithms have many potential benefits for mobile agents. The primary benefit is the potential for agents to become even more adaptive to situational changes in the environment and/or emergent security risks. There are secondary benefits such as the natural …

Variance Reduction Techniques For Estimating Quantiles And Value-At-Risk, Fang Chu

Dissertations

Quantiles, as a performance measure, arise in many practical contexts. In finance, quantiles are called values-at-risk (VARs), and they are widely used in the financial industry to measure portfolio risk. When the cumulative distribution function is unknown, the quantile can not be computed exactly and must be estimated. In addition to computing a point estimate for the quantile, it is important to also provide a confidence interval for the quantile as a way of indicating the error in the estimate. A problem with crude Monte Carlo is that the resulting confidence interval may be large, which is often the case …

New Data Structures, Models, And Algorithms For Real-Time Resource Management, Xinfa Hu

Dissertations

Real-time resource management is the core and critical task in real-time systems. This dissertation explores new data structures, models, and algorithms for real-time resource management.

At first, novel data structures, i.e., a class of Testing Interval Trees (TITs), are proposed to help build efficient scheduling modules in real-time systems. With a general data structure, i.e., the TIT* tree, the average costs of the schedulability tests in a wide variety of real-time systems can be reduced. With the Testing Interval Tree for Vacancy analysis (TIT-V), the complexities of the schedulability tests in a class of parallel/distributed real-time systems can be effectively …

Guppie: A Coordination Framework For Parallel Processing Using Shared Memory Featuring A Master-Worker Relationship, Sean Christopher Mccarthy

Dissertations

Most programs can be parallelized to some extent. The processing power available in computers today makes parallel computing more desirable and attainable than ever before. Many machines today have multiple processors or multiple processing cores making parallel computing more available locally, as well as over a network. In order for parallel applications to be written, they require a computing language, such as C++, and a coordination language (or library), such as Linda. This research involves the creation and implementation of a coordination framework, Guppie, which is easy to use, similar to Linda, but provides more efficiency when dealing with large …

Algorithms In Comparative Genomics, Satish Chikkagoudar

Dissertations

The field of comparative genomics is abundant with problems of interest to computer scientists. In this thesis, the author presents solutions to three contemporary problems: obtaining better alignments for phylogeny reconstruction, identifying related RNA sequences in genomes, and ranking Single Nucleotide Polymorphisms (SNPs) in genome-wide association studies (GWAS).

Sequence alignment is a basic and widely used task in bioinformatics. Its applications include identifying protein structure, RNAs and transcription factor binding sites in genomes, and phylogeny reconstruction. Phylogenetic descriptions depend not only on the employed reconstruction technique, but also on the underlying sequence alignment. The author has studied and established a …

Understanding Cognitive Differences In Processing Competing Visualizations Of Complex Systems, Madhavi Mukul Chakrabarty

Dissertations

Node-link diagrams are used represent systems having different elements and relationships among the elements. Representing the systems using visualizations like node-link diagrams provides cognitive aid to individuals in understanding the system and effectively managing these systems. Using appropriate visual tools aids in task completion by reducing the cognitive load of individuals in understanding the problems and solving them. However, the visualizations that are currently developed lack any cognitive processing based evaluation. Most of the evaluations (if any) are based on the result of tasks performed using these visualizations. Therefore, the evaluations do not provide any perspective from the point of …

Job Seeking And Job Application In Social Networking Sites : Predicting Job Seekers' Behavioral Intentions, Maria Marcella Plummer

Dissertations

Social networking sites (SNSs) are revolutionizing the way in which employers and job seekers connect and interact with each other. Despite the reported benefits of SNSs with respect to finding a job, there are issues such as privacy concerns that might be deterring job seekers from using these sites in their attempts to secure a job. It is therefore important to understand the factors that are salient in predicting job seekers' use of SNSs in applying for jobs.

In this research, a theoretical model was developed to explicate job seekers' intentions to use SNSs to apply for jobs. Two aspects …

Semantics And Efficient Evaluation Of Partial Tree-Pattern Queries On Xml, Xiaoying Wu

Dissertations

Current applications export and exchange XML data on the web. Usually, XML data are queried using keyword queries or using the standard structured query language XQuery the core of which consists of the navigational query language XPath. In this context, one major challenge is the querying of the data when the structure of the data sources is complex or not fully known to the user. Another challenge is the integration of multiple data sources that export data with structural differences and irregularities. In this dissertation, a query language for XML called Partial Tree-Pattern Query (PTPQ) language is considered. PTPQs generalize …

Virtual World Commerce Adoption (Vwca) : A Case Study Of Second Life Investigating The Impacts Of Perceived Affordances, Trust, And Need Satisfaction, Kamolbhan Olapiriyakul

Dissertations

Virtual worlds are computer-simulated worlds in which multi-players can simultaneously interact in a rich graphical environment. The development of virtual worlds, along with the massive growth of users, creates opportunities for business organizations. This dissertation involves many studies regarding virtual world adoption in business by virtual consumers.

Most of the research in Information Systems (IS) was conducted investigating factors influencing technology adoption, such as ease of use and usefulness, subjective norms and behavioral controls, self-efficacy, performance and effort expectancy, flow, etc. However, most of these research studies focused neither on design aspects related to affordances nor users' goal-oriented behaviors, such …

A Comparison Of Computer-Based Training And Traditional Classroom Training For The Sad Corporation Job Placement Team, Janice Brown Adams

Dissertations

Purpose: The purpose of this research study was to compare the effectiveness of computer-based training with traditional classroom training; both instructional delivery methods utilized the traditional classroom curriculum as a means of delivery for an on-the-job company-sponsored program. The JAW-SAD Human Resource Center (HRC) is a training facility for the SAD Corporation, a major international manufacturing company. The HRC is responsible for conducting continuous training and certification of SAD employees. Historically, training has been provided through conference workshops with a traditional classroom training format. The motivation and importance for this study was influenced by an administrative requirement to determine the …

Anomaly Detection Techniques For Ad Hoc Networks, Chaoli Cai

Dissertations

Anomaly detection is an important and indispensable aspect of any computer security mechanism. Ad hoc and mobile networks consist of a number of peer mobile nodes that are capable of communicating with each other absent a fixed infrastructure. Arbitrary node movements and lack of centralized control make them vulnerable to a wide variety of unknown and known attacks from inside as well as from outside. In this dissertation we propose two efficient statistical techniques for anomaly detection for these networks.

In order to take into account incomplete testing samples and the interaction among multiple features, we present BANBAD •- a …

Processing Techniques For Partial Tree-Pattern Queries On Xml Data, Pawel Placek

Dissertations

In recent years, eXtensible Markup Language (XML) has become a de facto standard for exporting and exchanging data on the Web. XML structures data as trees. Querying capabilities are provided through patterns matched against the XML trees. Research on the processing of XML queries has focused mainly on tree-pattern queries. Tree-pattern queries are not appropriate for querying XML data sources whose structure is not fully known to the user, or for querying multiple data sources which structure information differently. Recently, a class of queries, called Partial Tree-Pattern Queries (PTPQs) was identified. A central feature of PTPQs is that the structure …

In-Group / Out-Group Dynamics And Effectiveness In Partially Distributed Teams, Faina Privman

Dissertations

When organizations collaborate they often do so using partially distributed teams (PDTs). In a Partially Distributed Team there exist at least two distinct sub-groups. In addition, at least one of the sub-groups has two or more members that are geographically co-located. Co-located members can meet face to face; chat in the hallway; have lunch together; and otherwise socialize with one another. On the other hand, remote members must rely on technology to communicate and work together. This distinct characteristic of partially distributed teams makes them especially susceptible to the In-Group / Out Group dynamic (Huang and Ocker, 2006). This dynamic …

Design Development And Evaluation Of Collario, A Group Support System For Collaborative Scenario Creation, Xiang Yao

Dissertations

In the fields of Emergency Management and Business Continuity Planning, scenarios are a widely used tool for planning, training and knowledge sharing purposes. The ability to create and discuss emergency scenarios in virtual teams can lead to many potential applications, such as discussing emergency scenarios by world-wide experts, conducting on-line exercises, and creating Communities of Practices. Existing scenario creation systems, like NxMsel provided by FEMA, allow distributed groups to create scenarios together. However, collaborative support in these systems is generally limited.

This dissertation explores an innovative solution to provide various types of collaboration support around a knowledge structure and uses …

Topology Control Using Joint Power And Beam-Width Control In Hybrid Rf/Fso Mesh Networks, Osama Awwad

Dissertations

Most wireless networks are deployed strictly in the radio frequency (RF) domain, since RF channels provide natural support for radial broadcast operations. However, the downside of RF channels is that they introduce many limiting externalities that make providing scalable quality of service (QoS) support difficult, if not intractable. These well-known technical challenges include bandwidth scarcity, lack of security, high interference, and high bit error rates.

Faced with such daunting obstacles to QoS, the use of Free Space Optics (FSO) for wireless communications has been proposed in which it has the potential to support higher link data rates compared to present …

Predictive Decoding Of Neural Data, Yaroslav O. Halchenko

Dissertations

In the last five decades the number of techniques available for non-invasive functional imaging has increased dramatically. Researchers today can choose from a variety of imaging modalities that include EEG, MEG, PET, SPECT, MRI, and fMRI.

This doctoral dissertation offers a methodology for the reliable analysis of neural data at different levels of investigation. By using statistical learning algorithms the proposed approach allows single-trial analysis of various neural data by decoding them into variables of interest. Unbiased testing of the decoder on new samples of the data provides a generalization assessment of decoding performance reliability. Through consecutive analysis of the …

Autonomous Migration Of Vertual Machines For Maximizing Resource Utilization, Hyung Won Choi

Dissertations

Virtualization of computing resources enables multiple virtual machines to run on a physical machine. When many virtual machines are deployed on a cluster of PCs, some physical machines will inevitably experience overload while others are under-utilized over time due to varying computational demands. This computational imbalance across the cluster undermines the very purpose of maximizing resource utilization through virtualization. To solve this imbalance problem, virtual machine migration has been introduced, where a virtual machine on a heavily loaded physical machine is selected and moved to a lightly loaded physical machine. The selection of the source virtual machine and the destination …