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  • Thesis

  • Authors: Harper, Lois (2006)

  • From the variety of agent communication languages that have been proposed since the early 1990's, it can be seen that there is no general agreement on what constitutes a necessary core of semantics for agent communication languages. This has led some researchers to observe that agent communication languages have been implemented ad hoc. This dissertation develops and evaluates an approach towards representing the semantics of agent communication languages explicitly in the notation of conceptual graphs. The speech act theories of Austin, Searle and Habermas that are cited as having motivated the semantics of some agent communication languages are also represented in conceptual graph notation. These explicit representations support comparing the semantic features of agent communicati...

  • Thesis

  • Authors: Xie, Zhimin (2006)

  • We categorize American English phonemes into several groups: vowel, semi-vowel, nasal, whisper, fricative/affricative, closure/stop, silence and some special phonemes (/q/ and /dx/), among which five main groups (vowel, semi-vowel, nasal, fricative, stop) are further examined. Thereafter, we construct several detectors based on acoustic features for each phoneme group and compare them with HMM-based systems by testing on continuous speech data, TIMIT, and some data in unfavorable environments, like TIMIT with additive noise, and NTIMIT. To detect vowels, a compact vowel detector based only on two acoustic features, periodicity and energy, is implemented. It performs with 86.8% accuracy and 22.4% total error rate. Even under some adverse environments, it still works stably. To detec...

  • Thesis

  • Authors: Dai, Xiangtian (2006)

  • This thesis presents a visual tracking framework, Component-based Tracking. This framework combines low-level visual clues and constraints in a systematic way. It is based on a probabilistic graphical model to infer the marginal probability density function of the state of a tracked target. In this framework, all potential functions are approximated as weighted sums of multivariate Gaussians so probabilistic inference by message passing is equivalent to hypotheses combination and evaluation. The possibility of low level detectors not providing useful information is taken into account by the introduction of a null hypothesis. Simulation is conducted to verify the framework. In addition, a new kind of image-level region tracking method is studied. The estimation error of transformati...

  • Thesis

  • Authors: Marks, Tim Kalman (2006)

  • We present a generative graphical model and stochastic filtering algorithm for simulta¬neous tracking of 3D rigid and nonrigid motion, object texture, and background texture from single-camera video. The inference procedure takes advantage of the conditionally Gaussian nature of the model using Rao-Blackwellized particle filtering, which involves Monte Carlo sampling of the nonlinear component of the process and exact filtering of the linear Gaussian component. The smoothness of image sequences in time and space is exploited using Gauss-Newton optimization and Laplace’s method to generate proposal distributions for importance sampling. Our system encompasses an entire continuum from optic flow to template-based tracking, elucidating the conditions under which each method is optimal...

  • Thesis

  • Authors: Howse, Samuel (2006)

  • NummSquared Explained is the thesis version of the comprehensive formal docu¬ment NummSquared 2006a0 Done Formally, which is available at http / /nummist . com/poohbist/. Set theory is the standard foundation for mathematics, but often does not include rules of reduction for function calls. Therefore, for computer science, the untyped lambda calculus or type theory is usually preferred. The untyped lambda calculus (and several improvements on it) make functions fundamental, but suffer from non-terminating reductions and have partially non-classical logics. Type theory is a good foundation for logic, mathematics and computer science, except that, by making both types and functions fundamental, it is more complex than either set theory or the un¬typed lambda calculus. This document p...

  • Thesis

  • Authors: Niu, Linwei (2006)

  • Driven by the remarkable evolution of IC technology and the ever-increasing human appetite for higher computing power, the dramatically increased power /energy consumption for real-time embedded systems has presented a profound challenge to researchers and developers. Battery-operated embedded devices, which have already been ubiquitous, demand low power consumption to extend the battery life and thus the mission cycles. Even for power-rich platforms, rapidly elevated power consumption raised serious concerns regarding the reliability and packaging/cooling cost as a result of the heat dissipation. It is fair to say that en¬ergy reduction has become one of the most critical design issues in the design of next generation real-time embedded systems. Power/energy reduction for real-tim...

  • Thesis

  • Authors: Choi, Chiu Wo (2006)

  • A widely adopted approach to solving constraint satisfaction problems combines backtracking tree search with various degrees of constraint propagation for pruning the search space. One common technique to improve the execution efficiency is to add redundant constraints, which are constraints logically implied by others in the problem model and may offer extra information to enhance constraint propagation. However, some redundant constraints are propagation redundant and hence do not contribute additional propagation information to the constraint solver. In this thesis, we propose propagation rules as a tool to compare the propagation strength of constraints, and establish results relating logical and propagation redundancy. Redundant constraints arise naturally in the process of re...

  • Thesis

  • Authors: Walker, Jessie J. (2006)

  • The notion of mobility has always been a prime factor in human endeavor and achievement. This need to migrate by humans has been distilled into software entities, which are their representatives on distant environments. Software agents are developed to act on behalf of a user. Mobile agents were born from the understanding that many times it was much more useful to move the code (program) to where the resources are located, instead of connecting remotely. Within the mobile agent research community, security has traditionally been the most defining issue facing the community and preventing the paradigm from gaining wide acceptance. There are still numerous difficult problems being addressed with very few practical solutions, such as the malicious host and agent problems. These probl...

  • Thesis

  • Authors: Savova, Virginia (2006)

  • A central question for linguistics is how strings and structures relate to one another. The majority of frameworks that exist today assume that the hidden structures contain complete information about word order. Hence, the theory of grammar is only a theory of the structure-generating component. However, it is possible to design a theory of grammar which views the structure-generating component as separate from the linearization component. As a result, structural descriptions can directly incorporate multi-dominance, and consequently eliminate the need for transformational devices like movement. Another benefit is that linearization can take into account any combination of structural, morpho-phonological and discourse features, paving the way for a word or-der typology in the style...