Thesis (M.U.D.)--University of Hong Kong, 1999. / Includes bibliographical references (leaves 60-61).

published_or_final_version / Urban Design / Master / Master of Urban Design

published_or_final_version / Physics / Master / Master of Philosophy

published_or_final_version / Physics / Doctoral / Doctor of Philosophy

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Cassini-RPWS high resolution (20 Hz) Langmuir probe data was analyzed to find the source of fast variations in the electron density especially in the Enceladus plume region. The spatial scale on the variations is between 1 and 10 km in size. The approaches were to check for correlations between the plasma density and its variations on one hand, and boundary conditions such as the cracks on Enceladus surface as well as dust and single jets on the other hand. None of these mechanisms could be identified as the only or dominating source of observed fine structure, though partial correlation can sometimes be found and the comparison to dust presence is qualitative more than quantitative. Along the way the charging mechanism in the plume was found to be most likely due to solar UV ionization since the maximum electron density was found to be around 200km altitude. Also the deformation of the plume in the corotation direction is visible in the 20 Hz data.

The London dispersion interaction is responsible for attraction between non-polar molecules and is of great importance in describing structure and reactivity in many areas of chemistry. Dispersion is difficult to model accurately. Density Functional Theory (DFT) methods, widely used in computational chemistry today, do not include the necessary physics. This often leads to qualitatively incorrect predictions when DFT is applied to dispersion-bound systems. A novel DFT method has been developed which is capable of accurately modeling dispersion. Dispersion attraction between molecules arises when an instantaneous dipole moment in one molecule induces a dipole moment in a second molecule. Our approach proposes that the source of these instantaneous dipole moments is the position-dependent dipole moment of the exchange hole. The model is no more computationally expensive than existing DFTs and gives remarkably accurate dispersion coefficients, intermolecular separations, intermolecular binding energies, and intramolecular conformational energies. Our dispersion theory is also combined with previous post-exact-exchange models of dynamical and nondynamical correlation, yielding a unified exact-exchange-based energy functional called DF07. DF07 overcomes many of the outstanding problems in DFT arising from local exchange approximations. The DF07 model is shown to provide highly accurate results for thermochemistry, kinetics, and van der Waals interactions. / Thesis (Ph.D, Chemistry) -- Queen's University, 2007-11-29 21:57:09.045

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A technique for establishing L1 asymptotic unbiasedness of a kernel density estimator in Rd that does not depend on the form of the kernel function will be demonstrated. We will introduce the concept of a region sequence of a sequence of kernel functions and show how this can be used to give necessary and sufficient conditions for L1 asymptotic unbiasedness. These results are then applied to kernel density estimators whose form is given and a number of known and novel results are obtained.