Dissertation Defense

Algorithm Capability and Applications in Artificial Intelligence

Many algorithms are known to work well in practice on a variety of different problem instances. Reusing existing algorithms for problems besides the one that they were designed to solve is often quite valuable. This is accomplished by transforming an instance of the new problem into an input for the algorithm and transforming the output of the algorithm into the correct answer for the new problem. To capitalize on the efficiency of the algorithm, it is essential that these transformations are efficient.

An "Active Vision" Computational Model of Visual Search for Human-Computer Interaction

Visual search is an important part of human-computer interaction (HCI). The visual search processes that people use have a substantial effect on the time expended and likelihood of finding the information they seek. This dissertation investigates visual search through experiments and computational cognitive modeling. Computational cognitive modeling is a powerful methodology that uses computer simulation to capture, assert, record, and replay plausible sets of interactions among the many human processes at work during visual search.

Knowledge Support for Parallel Performance Data Mining

Parallel applications running on high-end computer systems manifest a complex combination of performance phenomena, such as communication patterns, work distributions, and computational inefficiencies. Current performance tools compute results that help to describe performance behavior, as well as to understand performance problems and how they came about. Unfortunately, parallel performance tool research has been limited in its contributions to large-scale performance data management and analysis, automated performance investigation, and knowledge-based performance problem reasoning.

Automated Methods to Infer Ancient Homology and Synteny

Establishing homologous (evolutionary) relationships among a set of genes allows us to hypothesize about their histories: how are they related, how have they changed over time, and are those changes the source of novel features? Likewise, aggregating related genes into larger, structurally conserved regions of the genome allows us to infer the evolutionary history of the genome itself: how have the chromosomes changed in number, gene content, and gene order over time?

Measuring the Internet AS Graph and Its Evolution

The AS graph is the "social network" that makes up the Internet infrastructure and determines inter-network traffic flow. How has this social network changed over time? Has traffic flow on the Internet been centralizing over time or decentralizing over time? We will build up the necessary framework to state these questions formally, and then we answer them using careful historical data analysis and some graph theory.

Ontology Databases

This dissertation defines ontology databases as a mapping from ontologies to relational databases in order to combine the expressiveness of ontologies with the scalability of relational databases. This mapping is sound and, under certain conditions, complete. That is, the database behaves like a knowledge base which is faithful to the semantics of a given ontology.

A software framework for simulation-based scientific investigations

This thesis provides a design and development of a software architecture and programming framework that enables domain-oriented scientific investigations to be more easily developed and productively applied. The key research concept is the representation and automation of scientific studies by capturing common methods for experimentation, analysis and evaluation used in simulation science. Such methods include {\em parameter studies}, {\em optimization}, {\em uncertainty analysis}, and {\em sensitivity analysis}.

Peer-to-Peer Streaming: Design and Challenges

Streaming multimedia content over the Internet is extremely popular mainly due to emerging applications such as IPTV, youtube and e-learning. All these applications require simultaneous streaming of multimedia content from one or multiple sources to a large number of users. Such applications impose unique requirements in terms of server bandwidth and playback delay which are difficult to achieve in a scalable fashion with the traditional client-server architecture.

Use of Ontologies in Information Extraction

Information extraction (IE) aims to recognize and retrieve certain types of information from natural language text. For instance, an information extraction system may extract key geopolitical indicators about countries from a set of web pages while ignoring other types of information. It has existed as a research field for a few decades and ontology-based information extraction (OBIE) has recently emerged as one of its subfields.

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