Graduation date: 1961

The properties of functional materials have been studied with density functional theory. The first type of materials that have been investigated is the so called diluted magnetic semiconductors. It is a new class of materials that could offer enhanced functionality by making use of spin in addition to the charge of the electron. (Mn,Al) co-doped ZnO has been investigated regarding the Al significance on ferromagnetic behavior using density functional theory within the generalized-gradient approximation plus on-site Coulomb interaction. Despite the presence of Al the system always shows antiferromagnetic behavior. The role of intrinsic defects on ferromagnetism in pure and Cr doped In2O3 was also studied. For pristine In2O3, In vacancy and O interstitial states are completely spin polarized. Moreover, these hole states will create Cr ions in mixed valence state, giving rise to a strong ferromagnetic coupling. The second type of functional materials studied are hydrogen storage materials for mobile applications. These materials are considered as alternative if hydrogen is to replace fossil fuels as a energy carrier. In the view of this a series of compounds containing boron, nitrogen and hydrogen has been examined with respect to electronic structure, dehydrogenation energy and hydrogen diffusion properties. One compound, NH3BH3, has many desirable properties as a hydrogen storage material. In an effort to improve those properties, one of the H atoms in the NH3 group was replaced by Li, Na or Sr. The calculated hydrogen removal energies of the hydrogen release reactions were found to be significantly improved. Finally, a coating material, Al2O3, for wear resistant coatings on high performance cemented carbide cutting tools has been investigated. Chemical vapor deposition grown Al2O3 has been used for decades by the industry. To improve the growth process H2S is added to the gas mixture. The catalytic effect of H2S on the AlCl3/H2/CO2/HCl chemical vapor deposition process has been investigated on an atomistic scale. By applying a combined approach of thermodynamic modeling and density functional theory it seems that H2S acts as mediator for the oxygenation of the Al-surface which will in turn increase the growth rate of Al2O3.

Space heating is one of the simplest and most appealing applications of solar energy. The Roof Integrated Solar Heating System (RISHS) initiated by the Sustainable Energy Centre (SEC) of the University of South Australia offers a practical solution for this application. The main objective of this project is to study the technical viability of this system for domestic applications in Australia. / The research work carried out and reported in this thesis brings together the pioneering work on RISHS, namely: modelling and analysis of both the roof integrated heating system and the phase change material (PCM) thermal storage. The work accomplished includes: developing an improved model for the PCM thermal storage unit (TSU), the development of a comprehensive collector model, the development of control strategy of the total system, the development of TRNSYS-based simulation tool for analysing individual component as well the total system, and analysis of the thermal performance of the system. / The new phase change thermal storage model allows for the inclusion of sensible heat both prior to and after the phase change is complete. It relies on the newly developed phase change processor (PCP) algorithm for accurately predicting the outlet temperature and heat transfer rate. The PCP algorithm facilitates the iterative process required to simulate the phase change process, a phenomenon which cannot be dealt with using the general conduction heat transfer equations. The work has also identified that a melting or freezing process of PCM can be divided into three stages; (a) the sensible heat exchange stage characterised by very high heat transfer rates, (b) predominant latent heat transfer stage with much reduced but relatively constant heat transfer rate, and (c) the stage of combined sensible and latent heat exchange with much a further reduced rate. Two temperature differences governing the melting and freezing processes have been introduced. It has been found that these two quantities affect melting and freezing significantly. Given the clear significance of these two newly introduced quantities, the research work questions some previous claims about the effects of natural convection in certain PCM TSU geometries. / The work on the roof integrated solar collector includes the development of a comprehensive solar collector model where the collector dimensions, construction and material properties become inputs or parameters. Using this model, thermal performance of the collector can be evaluated and the collector standard thermal parameters such as collector heat removal factor and collector heat loss coefficient can be evaluated. / The development of a control strategy of the total system which includes the house being heated, the collector, the PCM, the fan and the auxiliary heater, has been carried out. In the control strategy, the characteristics of each component are taken into account and the schedule of energy flow from the heat source and / or thermal storage are designed to maximise the solar contribution and minimise the auxiliary heating required throughout the heating period. To achieve this, an integrated control strategy of auxiliary and solar heating / thermal storage unit has been proposed. Using this approach, the optimum solar contribution for a specified RISIS can be established. The air mass flow rate and the room space temperature difference are the key parameters which influence the system thermal performance. / The subroutines for modelling the PCM thermal storage and the roof integrated solar collector and the system control strategy have been incorporated into the TRSNSYS simulation package to analyse the total system. The analysis carried out indicates that the RISHS is a technically viable system which can provide significant heating contribution for house heating in Adelaide and Melbourne. The introduction of the PCM thermal storage in the system is a technically viable option; it is in fact the main factor which improves RISHS overall performance. The analyses on three PCMs have revealed that the main factors which dictate their thermal performance are the charge temperature and the melting point (which affect the chargeability), mass flow rate and charge and discharge temperature differences. / The TRNSYS-based simulation tool developed during the research project is expected to become a reliable tool for designing any real system for any location and applications. / Thesis (PhDMechanicalEng)--University of South Australia, 2005.

Typescript (photocopy) / 259, 87 p. : ill. (some col.), charts ; 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 Electrical Engineering, 1978

No description available.

Thesis (M.S. - Hydrology and Water Resources)--University of Arizona, 1983. / Includes bibliographical references (leaves 204-207).

Proefschrift Universiteit van Amsterdam. / Met bibliogr., lit. opg. - Met samenvatting in het Nederlands.

Thesis ( Ph.D.) -- McMaster University, 1998. / Includes bibliographical references (leaves 214-218). Also available via World Wide Web.

Theses (M.S.)--Ohio University, November, 1980. / Title from PDF t.p.

Thesis (Ph. D.)--University of Melbourne, 1996. / Typescript (photocopy). Includes bibliographical references (leaves 190-195).