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  • Thesis

  • Authors: Gergle, Darren R. (2006)

  • For several decades, researchers and engineers have struggled with the development of systems to support distance collaboration. The failure of many collaborative technologies is due, in part, to a limited understanding of how groups coordinate in collocated environments and how the coordination mechanisms of face-to-face collaboration are impacted by technology. The major goal of this thesis is to address this deficiency by building a theoretical understanding of the role that shared visual information plays in supporting group communication and performance during task-oriented collaboration. This understanding is developed over three major stages: (1) the development of a paradigm and a series of empirical studies that decompose the features of shared visual information and task s...

  • Thesis

  • Authors: Herzig, Florian (2006)

  • We formulate a conjecture generalising the weight in Serre's Conjecture to n-dimensional representations p : Gal(U/Q) -* GLn(IF,) that are tamely ramified at p. A weight in this context is an irreducible representation of GLn(1Fp) over Pp. The conjecture describes the predicted set of weights in terms of the reduction modulo p of a Deligne-Lusztig repre¬sentation of GLn(Fp) which only depends on the restriction of p to the inertia subgroup at p. When n = 3 a weight conjecture had already been made by Ash, Doud, Pollack and Sinnott. The advantage of our conjecture is that it is more conceptual. It moreover predicts more weights for many representations p. We give computational examples which strongly suggest the existence of these extra weights. When n = 4 we obtain some theoretica...

  • Thesis

  • Authors: Reddy, Govardhan Patluri (2006)

  • The effect of solvent on the behavior of complex fluids is studied using simple models. The tools employed in the study are theoretical techniques such as integral equation theory and density functional theory, and computational tools such as Monte Carlo and molecular dynamics simulations. A variation of density functional theory(DFT) in which a water molecule is treated as a solute and the rest of the water molecules as solvent is used to study the structure of bulk water using the simple point charge water model. This study suggests that three body correlations are very important in theory to capture the structure of water at room temperature. The behavior of solvent near a solute particle is studied using DFT and grand canonical Monte Carlo simulations. A model in which the solve...

  • Thesis

  • Authors: Weeks, Bjorn (2006)

  • Soil covers are commonly used to isolate waste materials from the surrounding environment. The flux of moisture through a soil cover is one of the key parameters defining its performance. While the flux of moisture through soil covers has been well investigated for horizontal soil surfaces, there has been relatively little research on applications to sloped surfaces. This thesis examines moisture fluxes through soil covers in three dimensions, with a particular focus on the variations that occur in evaporation over a three dimensional (sloped) surface. A model for the prediction of net radiation over a three dimensional surface was developed, and verified with field experiments. Statistical analysis of the field data showed that the model could predict net radiation on sloped surfac...

  • Thesis

  • Authors: Mawatari, Tadamichi (2006)

  • The objective of this thesis is to establish mathematical models for predicting strains in the axial and other two orthogonal (transverse) directions of a multi-parameter Bragg grating sensor which is subjected to an axial and transverse loadings simultaneously. Previous work by other researchers has established models for predicting axial strains, but not a combination of those three strain components. Test specimens consisted of polarization maintaining Bragg grating sensors created in optical fibers with bow-tie stress applying parts. Each of the sensors had two Bragg wavelength peaks at around 1300 nm, and two others around 1550 nm, and those four peaks moved due to external stimuli such as applied loads and/or temperature changes. The change in wavelength from a certain refe...

  • Thesis

  • Authors: Garcia, Francisco J. (2006)

  • In this dissertation, we will study the following three non-linear problems: 1. The lineability problem for functionals. 2. The minimum-norm problem for translations. 3. The Banach-Mazur conjecture for rotations. As far as we know, all of them are currently open, and we believe that any approach to their solutions will constitute a work of great interest to the mathematical community. In this dissertation, we obtain progresses that lead to partial solutions of these problems.

  • Thesis

  • Authors: Choi, Hyun Il (2006)

  • Climate models, both global and regional, have increased in sophistication and are being run at increasingly higher resolutions. The land surface models (LSMs) coupled to these climate models have also evolved from simple bucket models to the new generation models needed to support sophisticated linkages and process interactions at small scales to assess their cumulative impact at larger scales. This is possible by substantially improving the land-surface parameterization in these models to account for subgrid processes. Although topographic data is one of the most readily available high resolution products with continental and global coverage, heterogeneity induced by topographic characteristics, such as slopes and curvatures, is generally not well represented in the models. These ...

  • Thesis

  • Authors: Kothapalli, Kishore (2006)

  • In this age of information, new models of information exchange methodologies based on overlay networks are gaining popular attention. Overlay networks provide a logical interconnection topology over an existing physical network. Overlay networks offer bene¬fits such as ease of implementation, flexibility, adaptability, and incremental deployability. Due to the wide range of applications and advantages, formal study of overlay networks is required to understand the various research challenges in this context. In this thesis, we study two classes of overlay networks namely peer-to-peer networks and wireless ad hoc networks. Our focus will be along two central issues in overlay net works: how to arrive at efficient topologies and how to provide efficient routing strategies. Peer-t...

  • Thesis

  • Authors: Liu, Rongsong (2006)

  • In this thesis, we study the transmission dynamics and spatial spread of vector borne diseases using mathematical models incorporating different factors, contributing to the com¬plicated transmission dynamics and spatiotemporal spread patterns of vector borne diseases. We focus on the demographic and disease ages of hosts, the culling structured by the age of the vector, the spatial movement of the disease hosts, and the heterogeneity in host populations. We address the above issues and the relevant modeling and analysis techniques via a detailed case studying of the invasion and spread of West Nile virus in North America. Models involved and developed include patchy models with both long-range and short-range dispersal, delay differential systems, non-local delayed reaction diffusi...

  • Thesis

  • Authors: Gu, Qian (2006)

  • Nanotechnology is considered a very important scientific discipline. It probably will offer tremendous growth opportunities to many industries. Numerous nanostructures showing interesting and practical properties have been synthesized. In order to fully understand and assemble these nanostructures into useful "nano-machines", investigations on individual nanostructures are needed. This thesis will present electron transport studies on individual organic molecules, a new method of fabricating asymmetric junctions to contact individual nanostructures, and synthesis, electrical and optical characterizations on single vanadium dioxide nanobeams. Chapter 1 serves as a brief introduction to the progress and challenges in nanotechnology. Chapter 2 first introduces single charge tunneling...