Open Access. Powered by Scholars. Published by Universities.®

Computer Sciences Commons

Open Access. Powered by Scholars. Published by Universities.®

University of Texas at Arlington

Discipline
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 601 - 630 of 666

Full-Text Articles in Computer Sciences

A Distributed Sensor Data Management Infrastructure Based On 802.15.4/Zigbee Networks, Tianqiang Li Dec 2006

A Distributed Sensor Data Management Infrastructure Based On 802.15.4/Zigbee Networks, Tianqiang Li

Computer Science and Engineering Theses - Archive

Wireless sensor networks consist of a certain number of autonomous devices with sensor, every device has certain detection functionality like light, temperature pressure etc. Communication by using the radio frequency make these spatially distributed devices feasible to oversee the activities in a large scale of area/space. 802.15.4/ZigBee networks are slated to run in the unlicensed frequencies. It is a packet-based radio protocol aimed at very low-cost, battery-operated widgets and sensors that can intercommunicate and send low-bandwidth data to each other. This thesis covers the content of a software solution of data management for an 802.15.4 networks. Its main contribution lies …


Generalization And Enforcement Of Role-Based Access Control Using A Novel Event-Based Approach, Raman Adaikkalavan Aug 2006

Generalization And Enforcement Of Role-Based Access Control Using A Novel Event-Based Approach, Raman Adaikkalavan

Computer Science and Engineering Dissertations - Archive

Protecting information against unauthorized access is a key issue in information system security. Advanced access control models and mechanisms have now become necessary for applications and systems due to emerging acts, such as the Health Insurance Portability and Accountability Act (HIPAA) and the Sarbanes-Oxley Act. Role-Based Access Control (RBAC) is a viable alternative to traditional discretionary and mandatory access control. RBAC has been shown to be cost effective and is being employed in various application domains on account of its characteristics: rich specification, policy neutrality, separation of duty relations, principle of least privilege, and ease of management. Existing RBAC approaches …


Learning State And Action Space Hierarchies For Reinforcement Learning Using Action-Dependent Partitioning, Mehran Asadi Aug 2006

Learning State And Action Space Hierarchies For Reinforcement Learning Using Action-Dependent Partitioning, Mehran Asadi

Computer Science and Engineering Dissertations - Archive

Autonomous systems are often dicult to program. Reinforcement learning (RL) is an attractive alternative, as it allows the agent to learn behavior on the basis of sparse, delayed reward signals provided only when the agent reaches desired goals. Recent attempts to address the dimensionality of RL have turned to principled ways of exploiting temporal abstraction, where decisions are not required at each step, but rather invoke the execution of temporally-extended activities which follow their own policies un- til termination. This leads naturally to hierarchical control architectures and associated learning algorithms. This dissertation reviews several approaches to temporal abstraction and hierarchical …


Context Aware Energy Conservation In Pervasive Computing Environments, Prathiba Joseph Aug 2006

Context Aware Energy Conservation In Pervasive Computing Environments, Prathiba Joseph

Computer Science and Engineering Theses - Archive

Extending battery lifetime is one of the most critical and challenging problems in mobile systems. When the mobile device sounds a low battery alarm, the user is given an ultimatum to quickly find a power source or suspend work. The greatest utility of mobile devices is their ability to be used anywhere, and at anytime. But power limitations of these devices seem to hinder this goal. The ever-growing needs of mobile users for increased lifetime of wireless devices imply that emerging wireless systems must be more energy-efficient than ever before. Cyber foraging or remote resource exploitation may be an efficient …


Evaluating Indexing And Routing Schemes For Spatial Queries In Sensor Networks, Raja Rajeshwari Anugula Aug 2006

Evaluating Indexing And Routing Schemes For Spatial Queries In Sensor Networks, Raja Rajeshwari Anugula

Computer Science and Engineering Theses - Archive

Recent advances in low-power sensing devices coupled with widespread availability of wireless ad-hoc networks, has fueled the development of sensor networks. These senor networks have various applications such as to monitor conditions at different locations (temperature, pressure, rainfall, vibrations etc.,), tracking of objects and so on. Each device is equipped with an energy source (usually with a battery), memory, CPU and communication bandwidth, which is severely constrained. Hence each sensor network is comprised of hardware for sensing, software for communication and computational algorithms. Spatial queries are commonly applied to sensor network, for example: "Find the highest temperature sensed in a …


An Application Of Parallel And Distributed Computing Methods To Approximate Pattern Matching Of Genetic Regulatory Motifs, Tushar Kumar Jayantilal Aug 2006

An Application Of Parallel And Distributed Computing Methods To Approximate Pattern Matching Of Genetic Regulatory Motifs, Tushar Kumar Jayantilal

Computer Science and Engineering Theses - Archive

Bioinformatics is a relatively new scientific field concerned with providing computational means and support to research in molecular biology and genetics. It draws from many different areas of computer science, including database theory, algorithm design and analysis, and artificial intelligence, to name just a few. In many applications, such as one described in this thesis, a biologist is interested in locating a particular pattern, or sequence motif, in a given string or set of strings over the four-letter DNA alphabet. In this thesis we present an efficient approach to locating promoter and other regulatory sequences in entire genomes or in …


A Relational Database Approach For Frequent Subgraph Mining, Subhesh Kumar Pradhan Jul 2006

A Relational Database Approach For Frequent Subgraph Mining, Subhesh Kumar Pradhan

Computer Science and Engineering Theses - Archive

Data mining aims at discovering interesting and previously unknown patterns from data sets. Further more, graph-based data mining represents a collection of techniques for mining the relational aspects of data represented as a graph. Complex relationships in data can be represented using graphs and hence graph mining is appropriate for analyzing data that is rich in structural relationships. Database mining of graphs, on the other hand, aims at directly mining graphs stored in a database using SQL queries. Several SQL-based mining algorithms have been developed successfully and their efficiency and scalability have been established. One of them is HDB-Subdue which …


A Graph-Based Approach For Modeling And Indexing Video Data, Jeongkyu Lee Jun 2006

A Graph-Based Approach For Modeling And Indexing Video Data, Jeongkyu Lee

Computer Science and Engineering Dissertations - Archive

With the advances in electronic imaging, storage, networking and computing, the amount of digital video has grown tremendously. The proliferation of video data has led to significant amount of research on techniques and systems for efficient video database management. In particular, extensive research has been done on video data modeling to manage and organize the data that is semantically rich and complicated. However, the enormous amount of data size and its complexity have restricted the progress on video data modeling, indexing and retrieval. In order to get around the problems, we turn to a graph theoretical approach for video database. …


Simulation Of Sensor Responses Of Advanced Security Systems, Janakiram Natarajan Jun 2006

Simulation Of Sensor Responses Of Advanced Security Systems, Janakiram Natarajan

Computer Science and Engineering Theses - Archive

Security systems are becoming an increasingly important area of research. Advanced security detection and surveillance systems that integrates a variety of detection mechanisms, like signals from different kinds of sensors, is expected to yield more accurate assessment than any one sensor analyzed individually. Designing and investigating these systems, to date, has relied primarily on physical deployments and experimentation. While the quality of the results from such efforts is excellent, the need to work with the physical systems directly imposes a substantial research impediment. One obvious possibility for widening the scope of what can be investigated is to employ simulation as …


Exception Handling Using Class Diversity, Qizhi Ye Jun 2006

Exception Handling Using Class Diversity, Qizhi Ye

Computer Science and Engineering Theses - Archive

Software reliability has been received more and more attention not only in mission critical system but also in commercial software system. Developing robust software must consider faults caused by abnormal situations or exceptions. Although modern programming languages like Java and C++ provide sophisticated exception handling mechanisms for detecting and handling exceptions, many potential runtime exceptions are not caught and handled because runtime exceptions could occur anywhere and could be numerous in a typical program. If an uncaught runtime exception occurs during program execution, then the execution will terminate abnormally, resulting in a system crash. The thesis proposes a framework that …


Relative Clock Drift Rate Based Secure Time Synchronization For Wireless Sensor Networks, Jae Sung Choi May 2006

Relative Clock Drift Rate Based Secure Time Synchronization For Wireless Sensor Networks, Jae Sung Choi

Computer Science and Engineering Theses - Archive

Time synchronization is critical issue to many wireless sensor network applications such that target tracking, TDMA radio scheduling, and secure localization. However, the most of existing time synchronization algorithms in wireless sensor networks did not consider malicious attacks in hostile environments. In this thesis, we propose a Relative Clock Drift Rate Based Secure Time Synchronization (RSTS) schemes to address security problems. RSTS alleviates delay attacks and incorrect time stamp transmissions caused by external or internal malicious attackers. We discuss a simple estimation technique to calculate a relative clock drift rate between sender-receiver clocks, because the estimated relative clock drift rate …


Towards Optimum Play-Out Buffering Delay In Voice Over Ip, Ruchir Pramod Shende May 2006

Towards Optimum Play-Out Buffering Delay In Voice Over Ip, Ruchir Pramod Shende

Computer Science and Engineering Theses - Archive

Voice over Internet Protocol (VoIP) or transmission of real-time voice packets over the Internet is slowly emerging as a cost-effective alternative to the traditional Public Switched Telephone Network (PSTN). However, varying end-to-end delay and packet loss, which are inherent in a packet-switched network like the Internet, lead to relatively lower quality of VoIP calls. The call quality can be improved by adaptively adjusting the play-out buffer at the receiver to reduce the impact of the delay and jitter. A standard play-out strategy uses a weighted moving average of the mean and variance of network delay to adaptively set the play-out …


Concept-Based Search Using Parallel Query Expansion, Rahul Rajiv Joshi May 2006

Concept-Based Search Using Parallel Query Expansion, Rahul Rajiv Joshi

Computer Science and Engineering Theses - Archive

We address the problem of irrelevant results for short queries on Web search engines. Short queries fail to provide sufficient context to disambiguate possible meanings associated with the search terms resulting in a set of irrelevant pages that the user has to filter through navigation and sometimes examination. First, we predict the potential concept topics, which are the domains for the search terms. This prediction is based on word occurrences and relationships observed in the various domains (categories) of a corpus. Next, we expand the search terms in each of the predicted domains in parallel. We then submit separate queries, …


Ubca: A Utility Based Clustering Architecture For Peer-To-Peer Networks, Brent Lagesse May 2006

Ubca: A Utility Based Clustering Architecture For Peer-To-Peer Networks, Brent Lagesse

Computer Science and Engineering Theses - Archive

Use of the Peer-to-Peer (P2P) architecture has recently spread in popularity. File sharing and ad hoc networks have contributed to the architecture's usage. P2P generates new challenges in scalability, fairness, and quality of service. Current solutions tend to fall into two main areas: incentives and system design. Incentive-based approaches appeal to the self-interested nature of peers by requiring service to the system in order to access resources. System design includes distributed hash tables and graph-theoretical based designs which have seen some success, but also result in new problems. We introduce a Utility-Based Clustering Architecture, UBCA, designed to address scalability, fairness, …


Alternative Architectures For Improving Document Readability, Ankur Bora May 2006

Alternative Architectures For Improving Document Readability, Ankur Bora

Computer Science and Engineering Theses - Archive

A number of tools have been developed to improve the readability of documents. These tools assist users to make changes which result in an easy to read document. Most of these tools were developed for users who work independently with little interaction with other users. However, in recent years, because of the proliferation of Internet, there has been increased collaboration between users. A user may need to share his document repositories with others so that both can benefit. Another set of users may work with information from a specific domain. These domains may be located in different geographical areas. Some …


Anytime Top-K Queries On Exact And Fuzzy Data, Bhushan P. Chaudhari May 2006

Anytime Top-K Queries On Exact And Fuzzy Data, Bhushan P. Chaudhari

Computer Science and Engineering Theses - Archive

Top-k queries on large multi-attribute data sets are fundamental operations in information retrieval and ranking applications. In this thesis, we initiate research on the anytime behavior of top-k algorithms on exact and fuzzy data. In particular given specific topk algorithms we are interested in studying their progress towards identification of the correct result at any point of the algorithms' execution. We adopt a probabilistic approach where we seek to report at any point the scores of the top-k results the algorithm has identified, as well as associate a confidence with this prediction. Such functionality can be a valuable asset when …


Towards A Stronger Peer-To-Peer Anonymous System, Arjun R. Nambiar May 2006

Towards A Stronger Peer-To-Peer Anonymous System, Arjun R. Nambiar

Computer Science and Engineering Theses - Archive

Anonymous communications systems on the Internet provides protection against eavesdroppers and others that seek to link users with their communications. These systems have many important applications in areas such as law enforcement, intelligence gathering, business privacy, anonymous publishing, and personal privacy. Currently deployed systems rely on a relatively small set of advertised servers to forward messages for the user. These systems can suffer from scalability problems, with potentially large bandwidth and system overhead costs, and the servers themselves can be targets of direct attacks. Peer-to-peer anonymous communications systems, such as Tarzan[1] and MorphMix [2], have been proposed as a way …


Investigation Of Techniques To Increase The Scalability Of Graph-Based Data Mining Algorithms., Srilatha Inavolu May 2006

Investigation Of Techniques To Increase The Scalability Of Graph-Based Data Mining Algorithms., Srilatha Inavolu

Computer Science and Engineering Theses - Archive

Frequent subgraph pattern recognition and graph-based relational learning have been an emerging area of data mining research with scientific and commercial applications. At the kernel of these algorithms are the computationally-expensive graph and subgraph isomorphism tests. The graph isomorphism problem consists in deciding whether two graphs are isomorphic i.e., whether there is a one-one mapping between the vertices of the two graphs that respects the edge connections. Many graphs will be depicted quite differently but in actuality have the same inherent structure. This leads to the isomorphism problem. The graph isomorphism problem belongs to the class of NP problems and …


Multiple Object Tracking Using Particle Filters, Hwangryol Ryu May 2006

Multiple Object Tracking Using Particle Filters, Hwangryol Ryu

Computer Science and Engineering Theses - Archive

We describe a novel extension to the Particle filter algorithm for tracking multiple objects. The recently proposed algorithms and the variants for multiple object tacking algorithms estimate multi-modal posterior distributions that potentially represent the multiple peaks (i.e., multiple tracked objects). However, the speci¯c state representation does not demonstrate birth, death and more importantly partial/complete occlusion of the objects. Furthermore, the weakness of the Particle Filter such that the representation may increasingly bias the posterior density estimates toward objects with dominant likelihood makes the multiple object tracking algorithms more di±cult. To circumvent a sample depletion problem and maintain the computational complexity …


Supervised Learning From Embedded Subgraphs, Joseph T. Potts May 2006

Supervised Learning From Embedded Subgraphs, Joseph T. Potts

Computer Science and Engineering Dissertations - Archive

We develop a machine learning algorithm which learns rules for classification from training examples in a graph representation. However, unlike most other such algorithms which use one graph for each example, ours allows all of the training examples to be in a single, connected graph. We employ the Minimum Description Length principle to produce a novel performance metric for judging the value of a learned classification. We implement the algorithm by extending the Subdue graph-based learning system. Finally, we demonstrate the use of the new system in two different domains, earth science and homeland security.


Power And Distortion Optimized Video Coding For Pervasive Computing Applications, Yongfang Liang Apr 2006

Power And Distortion Optimized Video Coding For Pervasive Computing Applications, Yongfang Liang

Computer Science and Engineering Dissertations - Archive

This dissertation investigates video encoding schemes for pervasive computing applications that must ensure low power consumption in addition to high compression efficiency. The contribution of the dissertation is the formulation of a theoretical problem that captures the joint optimization of power and distortion in video coding. The study of the complexity distribution of typical video encoders helps to develop a complexity-scalable video encoding architecture that includes several control parameters to adjust the power consumption of the major modules of the encoder. An analytic framework to model, control and optimize the power-rate-distortion is developed, which facilitates the development of optimization schemes …


Application Of Software Engineering Best Practices And Principles To Small Development Teams, Miles Phillips Apr 2006

Application Of Software Engineering Best Practices And Principles To Small Development Teams, Miles Phillips

Computer Science and Engineering Theses - Archive

The motivation of this thesis comes from the professional experience of the author. Having worked with very small software development teams in various capacities, he realized that significant improvements could be achieved by the application of modern software engineering practices and principles. This paper is the result of researching how the principles and practices promoted by the leading software development authors can be applied to the small development team as they transition from "programming in the small" to "programming in the medium." This paper investigates the best practices and principles in various case studies with the objective to clearly define …


The Advantages Of Implementing Software Engineering Process Models, Ricky Don Preuninger Apr 2006

The Advantages Of Implementing Software Engineering Process Models, Ricky Don Preuninger

Computer Science and Engineering Theses - Archive

The North Atlantic Treaty Organization Science Committee had discussions on the topic concerned the state of Computer Science. There were worldwide issues with the development of software, the crisis being that software projects did not seem ever to complete. The study group coined the term "software engineering" to be provocative and implying need for software manufacturing to be similar to traditional branches of engineering. In the beginning, individual programmers used whatever means worked to build software. Formal methods of design or programming did not exist. Programmers were never able to give a definitive estimate as to how long a project …


A Performance Evaluation Of Alternate Numbering Based Xml Indexing Techniques, Chul Ho Ahn Apr 2006

A Performance Evaluation Of Alternate Numbering Based Xml Indexing Techniques, Chul Ho Ahn

Computer Science and Engineering Theses - Archive

Since XML became a standard of representing semi-structured data and exchanging format over the web, the sheer volume of XML data has become larger. While relational database represents data as a structured format, XML represents data in a self-describing way as a hierarchical tree structure. For expediting query processing over XML, many different types of indexing techniques have emerged. We will focus on numbering-based indexing techniques in this thesis. We will present performance comparison according to different XPath queries among three distinct numbering based XML indexing named GENE (Generic numbering based), XISS (Range based numbering), and XACC (Dimension based numbering) …


Monitorexplorer: A State-Space Exploration Based Tool To Test Java Monitors Implementations, Vidur Gupta Apr 2006

Monitorexplorer: A State-Space Exploration Based Tool To Test Java Monitors Implementations, Vidur Gupta

Computer Science and Engineering Theses - Archive

A monitor is a concurrency construct that encapsulates data. There are many application classes which are written using the Java Monitors and these are difficult to test due to the inherent complexities of the concurrent programs. The key challenge is to be able to trace all possible execution paths and then able to reproduce them for regression testing. Our work explores the state-space of the monitor application. The state space is explored in the depth first fashion. At each state the next possible transition is executed. This process is repeated till a duplicate or invalid state is detected. The key …


Bridging Two Grids: The Sam-Grid/Lcg Integration Project, Tummalapalli Sudhamsh Reddy Apr 2006

Bridging Two Grids: The Sam-Grid/Lcg Integration Project, Tummalapalli Sudhamsh Reddy

Computer Science and Engineering Theses - Archive

SAM-Grid is an integrated data, job, and information management system. SAM-Grid addresses the distributed computing needs of the Dzero experiment at Fermi National Accelerator Laboratory, Batavia, IL. The system typically relies on SAM-Grid specific services deployed at the remote sites in order to manage the computing and storage resources. Such deployment requires special agreements with each resource provider, and it is a labor intensive process. Some members of the Dzero VO also have access to computing resources through the Large Hydron Collider Computing Grid (LCG) infrastructure. Therefore, Dzero users can enter into resource sharing agreements and deployment of standard middleware …


Interactive Animated Concept Map Generation - Using Dynamic Animations, Suneel Vana Dec 2005

Interactive Animated Concept Map Generation - Using Dynamic Animations, Suneel Vana

Computer Science and Engineering Theses - Archive

We present a visualization tool, which is useful for the illustration of educational concepts using interactive animated concept maps. This system serves as a presentation tool which provides a collection of multimedia elements (images, animations, audios clips and video clips), a collection of animated presentation templates and an interface by using which users can retrieve the multimedia elements from the multimedia database and generate the dynamic animations by placing the selected elements into the placeholders of the templates. The system generates the animated presentation by replacing embedded multimedia objects and their properties as desired by its users. A multimedia information …


Monitoring Health By Detecting Drifts And Outliers In Patterns Of An Inhabitant In A Smart Home, Gaurav Jain Dec 2005

Monitoring Health By Detecting Drifts And Outliers In Patterns Of An Inhabitant In A Smart Home, Gaurav Jain

Computer Science and Engineering Theses - Archive

The elderly, along with people with disabilities or chronic illness, are most often dependent on some kind of formal or informal care. They are forced to move to a place where they can be cared for. Automatic health monitoring allows them to maintain their independence and continue living at home longer by continuously providing key health and activity information to caregivers. In this thesis, we present a novel technique, called the Health Monitoring System (HMS), which is a data-driven automated monitoring system for detecting changes in the patterns of activities/inactivity, health data and the living environment. HMS classifies these changes …


Infosearch: A System For Searching And Retrieving Documents Using Complex Queries, Nikhil Deshpande Dec 2005

Infosearch: A System For Searching And Retrieving Documents Using Complex Queries, Nikhil Deshpande

Computer Science and Engineering Theses - Archive

The colossal amount of information available online has resulted in overloading users who need to navigate this information for their routine requirements. Although search engines have been effective in reducing this information overload, they support only queries involving keywords and Boolean operators. There are certain application domains where more expressive ways of searching are necessary. Consider searching a full-text patent database for documents containing more than n occurrences of a pattern, or for documents that have a particular pattern followed by another pattern within a specified interval. Such complex patterns involving pattern frequency and sequence, as well as patterns involving …


Customization Of A Generic Search Engine By Adding User Categories, Ajay Mohandas Madkaiker Dec 2005

Customization Of A Generic Search Engine By Adding User Categories, Ajay Mohandas Madkaiker

Computer Science and Engineering Theses - Archive

The current search engines available on the Net are generic in nature. They do not consider user preferences and treat all users information needs in the same way. As a result they frequently return a large number of links, that do not meet the user's information need. This requires more searching to find what the user is looking for. For example if a user is interested in a particular game, e.g. cricket, and enters the query world cup, a generic search engine would return links of all the sports that hold a world cup. The user has to browse through …