154 leaves : ill., photos ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physics, 1976

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 66-72). Also available via the Internet.

Thesis (Ph. D.)--Florida State University, 2005. / Advisor: Daniel McGee, Sr. , Florida State University, College of Arts and Sciences, Dept. of Statistics. Title and description from dissertation home page (viewed Jan. 24, 2006). Document formatted into pages; contains xi, 124 pages. Includes bibliographical references.

Diss.-- Univ. of Innsbruck, 2008. / In SpringerLink. Titre de l'écran-titre (visionné le 19 avril 2010). Bibliogr. Publié aussi en version papier.

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Surface photometry is one area of extragalactic studies in which information is urgently needed by optical as well as radio astronomers. The aim of this thesis is to supply some of the photometric parameters for 48 galaxies in two international colour systems. The reader will notice that descriptions are included of many detailed aspects of the work and little attention is paid to the more basic problems. This is because the discussion of the basic problems in photo-graphic photometry of galaxies formed the contents of an M.Sc. thesis. Volume one is devoted to a detailed description of the methods used for the reduction techniques together with a discussion of the results, while volumes two and three contain the photometric data. In the first volume, the first chapter is concerned with previous investigations and the following chapter contains detailed descriptions of the instruments and methods used in the preliminary plate reductions. The subject of isophotometry is dealt with in the third chapter, while in the fourth and fifth chapters respectively, mention is made of the reduction techniques, together with conclusions which may be deduced from the photometric data. This information is given in volume two for those galaxies with NGC catalogue numbers from 4189 to 4459, while the data for objects from NGC 4461 to NGC 4762 are listed in the third volume of the thesis.

Planetary systems around other stars have been observed to be far more diverse than what would be expected from the example of the Solar System. Exoplanets have been detected with a wide range of sizes and separations from the host star, with a range of orbital properties including large eccentricities and small inter-planet mutual inclinations. How representative these planetary systems are, however, is unclear due to detection techniques being more sensitive to planets on close orbits around the host star. It is possible therefore that a population of wide-orbit planets could be present in these systems and be evading detection. These planets may play a significant role in forming and shaping planetary systems, resulting in the architecture that is observed today. Currently, one of the major ways of inferring the presence of wide-orbit planets, besides directly detecting them, is to consider the dynamical impact they would have on known planets. In the first part of this thesis I consider how the eccentricities of known planets are affected due to long term dynamical interactions with a wide-orbit planet. I show that the eccentricity of a known planet in a system can periodically be significantly increased due to these interactions, provided that there are a total of two planets in the system. For systems with multiple known planets I show that the inner planets can protect each other against long term eccentricity perturbations from a wide-orbit planet. Following on from this investigation, I show how the inclinations of planets are affected due to long term interactions with a wide-orbit planet. Specifically, I consider how this interaction affects the probability that planetary systems are observed to transit. I find that the presence of wide-orbit planets in transiting planetary systems can help explain the so-called `Kepler-Dichotomy' which describes the apparent excess of observed single transiting systems compared with multi-planet transiting systems. Wide-orbit planets do not just dynamically interact with other planets in a system but also with small debris type bodies, akin to the Asteroid and Kuiper belts in the Solar System. In the second half of this thesis, I consider the planetary system HR8799 which is known to host four planets and two populations of debris which lie both internally and externally to the known planets. I find, through suites of N-body simulations, that a hypothetical planet in HR8799 sculpts an outer debris population that agrees more strongly with observations, compared with what would be expected by considering the known planets in isolation. Finally, for the last part of this thesis, I describe a survey that is looking to observe wide-orbit planets in close-by planetary systems directly. The observations and analysis for this survey is currently on-going, however I show preliminary results including systems with and without potential companion detections.

D.Phil. (Electrical and Electronic Engineering) / The ubiquitous missing data and its pervasiveness in large scale datasets (such as insurance datasets) have inspired research conducted on this thesis to focus on techniques that sustain high accuracies and robustness. It is a consensus in research and in practice that missing data reduces the quality of data and negatively affects the accuracy in classification. The increase in pervasiveness of missing data affects the accuracy and robustness (or resilience) of classifiers. This effectively impacts decision making and calculation of premiums. The goal of the thesis is to present methods that will improve the accuracy and/or robustness of classifiers in the presence of missing data in insurance datasets. The first contribution in this thesis is a comprehensive comparative study of machine learning techniques (classifiers) in the presence of increasing missing data. The study explores and scrutinises their performance and robustness. The classifiers are the repeated incremental pruning to produce error reduction (RIPPER), naïve Bayes (NB), k-nearest neighbour (k-NN), logistic discriminant analysis (LgDA) and support vector machines (SVM). The study reveals that the sensitivity of the classifiers decreases with increasing missing data rate. The RIPPER shows better performance overall, whilst the NB shows better robustness as the quality of the data deteriorates. A second contribution presented in this thesis is a novel relevance determination (ARD) ensemble for effective attribute selection in insurance datasets with large number of attributes and contains missing data. ARD ensemble applies the Bayesian neural networks and evidence framework to find and order attributes based on their relevance to the target outcome. The data is partitioned into numerical and nominal subsets. Each ARD in the ensemble is then constructed using each of the subsets. The combined outcome of each ARD is scrutinised using a confidence factor and the most relevant attributes are selected. Missing data imputation is performed using the mean-mode imputation. The performance of the ARD ensemble is compared to that of the principal component analysis (PCA). The results show that classifiers that use the ARD ensemble achieve high accuracies and sustain robustness than when applied using the PCA.

A seismic explosion program has been carried out in the Vancouver Island-Strait of Georgia area of Western Canada. The program included a relatively-intensive survey in the Strait of Georgia between Campbell River and the south end of Texada Island, as well as a number of longer range refraction lines extending from Kelsey Bay along the coast as far south as northern California, and east through the mountains to a distance of 700 km. Gravity readings were obtained at intervals of about ten km. along the east coast of Vancouver Island as well as for a number of east-west traverses. Readings were also obtained for a few locations on the British Columbia mainland. Except for a marked positive trend in the Victoria area, the regional value of the Bouguer anomaly for the Vancouver Island area is nearly zero. The average structure for the area, derived from the seismic refraction observations consists of a layer of volcanic and granitic strata less than five km. in thickness, and an intermediate layer with a constant velocity for compressional waves of 6.66 km/sec, 46 km. thick. A velocity of about 7.7 km/sec. for the mantle has been observed along unreversed refraction lines, both along the coast and east through the mountains. Interpretation of the refraction observations has been based mainly on first arrival phases. The observed regional gravity anomaly is compatible with the crustal model obtained from the seismic results. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The Twomey effect describes the radiative forcing associated with a change in cloud albedo due to an increase in anthropogenic aerosol emissions. It is driven by the perturbation in cloud droplet number concentration (1Nd; ant) in liquid-water clouds and is currently understood to exert a cooling effect on climate. The Twomey effect is the key driver in the effective radiative forcing due to aerosol–cloud interactions, but rapid adjustments also contribute. These adjustments are essentially the responses of cloud fraction and liquid water path to 1Nd; ant and thus scale approximately with it. While the fundamental physics of the influence of added aerosol particles on the droplet concentration (Nd) is well described by established theory at the particle scale (micrometres), how this relationship is expressed at the large-scale (hundreds of kilometres) perturbation, 1Nd; ant, remains uncertain. The discrepancy between process understanding at particle scale and insufficient quantification at the climate-relevant large scale is caused by co-variability of aerosol particles and updraught velocity and by droplet sink processes. These operate at scales on the order of tens of metres at which only localised observations are available and at which no approach yet exists to quantify the anthropogenic perturbation. Different atmospheric models suggest diverse magnitudes of the Twomey effect even when applying the same anthropogenic aerosol emission perturbation. Thus, observational data are needed to quantify and constrain the Twomey effect. At the global scale, this means satellite data. There are four key uncertainties in determining 1Nd; ant, namely the quantification of (i) the cloud-active aerosol – the cloud condensation nuclei (CCN) concentrations at or above cloud base, (ii) Nd, (iii) the statistical approach for inferring the sensitivity of Nd to aerosol particles from the satellite data and (iv) uncertainty in the anthropogenic perturbation to CCN concentrations, which is not easily accessible from observational data. This review discusses deficiencies of current approaches for the different aspects of the problem and proposes several ways forward: in terms of CCN, retrievals of optical quantities such as aerosol optical depth suffer from a lack of vertical resolution, size and hygroscopicity information, non-direct relation to the concentration of aerosols, difficulty to quantify it within or below clouds, and the problem of insufficient sensitivity at low concentrations, in addition to retrieval errors. A future path forward can include utilising co-located polarimeter and lidar instruments, ideally including high-spectral-resolution lidar capability at two wavelengths to maximise vertically resolved size distribution information content. In terms of Nd, a key problem is the lack of operational retrievals of this quantity and the inaccuracy of the retrieval especially in broken-cloud regimes. As for the Nd-to-CCN sensitivity, key issues are the updraught distributions and the role of Nd sink processes, for which empirical assessments for specific cloud regimes are currently the best solutions. These considerations point to the conclusion that past studies using existing approaches have likely underestimated the true sensitivity and, thus, the radiative forcing due to the Twomey effect.