<p> The transmit-power control (TPC) problem is a fundamental problem in cognitive radio design, which aims at determining transmit-power levels for secondary users across available subcarriers. This thesis studies both the theory and the algorithms for the TPC problem for cognitive radio networks, and specifically examines the problem under two different limitations: an interference-power limitation and a low-power limitation. First, the TPC problems are cast into game-theoretic models and the sufficient and necessary optimality conditions ·for solutions are derived. Sufficient conditions for the existence, uniqueness and stability of a solution are presented as well. Second, the fast iterative water-filling controller (FIWFC) for the TPC problem is developed, which is linearly convergent under certain conditions. The computational complexity is lower than for the iterative water-filling controller (IWFC) for digital subscriber lines. In order to evaluate the FIWFC, simulations are carried out for both stationary and nonstationary radio environments. In addition, the performance of the FIWFC is evaluated, given the presence of measurement errors. The results of these various simulations show that the FIWFC outperforms IWFC in terms of convergence speed in all cases. </p> / Thesis / Doctor of Philosophy (PhD)

<p> In recent years, a number of qualitative calculations of various nuclear properties have been undertaken based on a "pairing-plus-quadrupole" force model. The present work involves an extension of the techniques associated with this model and is an investigation of the extent to which it can quantitatively predict properties of the low-lying levels of spherical even-even nuclei.</p> <p> As a particular application, the energies of several of the low-lying levels and the reduced transition probabilities for the first 2+ levels are calculated for the even isotopes of lead.</p> <p> These calculations show in a natural way how collective levels arise, and help to clarify the nature both of these and of the non-collective levels.</p> / Thesis / Doctor of Philosophy (PhD)

<p> Twenty-two energy levels of 105Ru populated in the beta decay of 105Ru have been determined. The internal conversion coefficients of the eighteen strongest transitions were measured using a magnetic spectrometer and were used to obtain their multipole assignments. The energies and intensities of seventy gamma rays were measured using germanium detectors and scintillation counters. Gamma-gamma and beta-gamma coincidence measurements carried out with magnetic spectrometers, NaI(Tl) and Ge(Li) detectors were used with these energy measurements to establish a decay scheme. An interpretation of the decay scheme in the light of current nuclear models was attempted.</p> / Thesis / Doctor of Philosophy (PhD)

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