viii, 178 leaves : ill., graphs ; 31 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, 1976

The chemistry during regrinding is critical to flotation. It has significant effects on mineral surface properties and can lead to different mineral floatabilities. This research seeks to quantify contributing factors to changes in mineral flotation behavior with grinding and regrinding. The influence of the particle breakage mechanism on mineral floatability is also investigated. In this research, sulphide mineral surface species and hydrophobicity were analyzed by a range of techniques, including X-ray photoelectron spectroscopy (XPS), surface area measurement (BET), ethylene diamine-tetra acid (EDTA) extraction and contact angle measurements. / Thesis (PhD)--University of South Australia, 2010

The release of sodium during the combustion of black liquor is a significant source of fume formation in a kraft recovery boiler, affecting efficiency in a pulp and paper mill. The fume is deposited on the surface of heat exchanger tubes in the upper furnace, causing fouling and corrosion, especially to the superheaters. This thesis reports on work done to develop improved understanding of fume formation. The mechanisms of sodium release during each stage of black liquor combustion are influenced by the surface temperature. The addition of boron to the black liquor, which debottlenecks the recausticizing plant by a reduction in lime usage, also influences the characteristics of black liquor combustion, such as combustion time and swelling. Previously, no effective measurement technique has been available to quantify sodium concentration in the plume of a burning black liquor droplet with or without boron, or to record the distribution of surface temperature through the time history of a burning droplet. This thesis reports on the adaptation of two techniques for the measurement of the release of atomic sodium and the temperature history, and their application to investigate several aspects of the release of atomic sodium during combustion of black liquor in a flat flame environment. The simultaneous employment of a planar laser-induced fluorescence (PLIF) technique with an absorption technique has been adapted to allow quantitative measurement of the release of atomic sodium. The absorption technique has been employed to correct for both fluorescence trapping due to absorption and attenuation by high concentration of the atomic sodium in the plume, and for collisional quenching by the other major gas components present in the flat flame. An independent assessment was performed using kinetic calculations, based on measured total sodium that is residual in a particle obtained at different stages in the combustion process. These independent assessments were used to provide greater insight in to the release process and to cross-check. The influence of both the initial diameter of the droplet and addition of boron to the black liquor on the temporal release and the release rate of atomic sodium during the combustion have been performed using the present PLIF technique. The second technique, two-dimensional two-colour optical pyrometry, has been adapted to measure the distribution of surface temperature and the swelling (change in surface area) of a burning black liquor droplet. The influence of surface temperature or the change in the external surface area of the droplet on the release of atomic sodium during the combustion of black liquor has been assessed through concurrent use of both adapted techniques. The highest concentration of atomic sodium was measured in the final stage of combustion that of smelt coalescence, where it is an order of magnitude greater than in the other stages combined. While the extensive release of atomic sodium at high temperature in this final combustion stage occurs in only a relatively small percentage of droplets in a kraft recovery boiler, the effect could still be significant in fume formation. This is because the extensive release is expected to occur in the very small droplets, predominantly generated by splitting or physical ejection. Small droplets will have a very short combustion time and so could remain in suspension within hot gases for sufficient time for extensive release of sodium. These measurements outcomes can be used to support the future development of sub-models for computational fluid dynamics (CFD) models in order to better understand and optimise fume formation in a kraft recovery boiler. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1474431 / Thesis (Ph.D.) - University of Adelaide, School of Mechanical Engineering, 2009

The release of sodium during the combustion of black liquor is a significant source of fume formation in a kraft recovery boiler, affecting efficiency in a pulp and paper mill. The fume is deposited on the surface of heat exchanger tubes in the upper furnace, causing fouling and corrosion, especially to the superheaters. This thesis reports on work done to develop improved understanding of fume formation. The mechanisms of sodium release during each stage of black liquor combustion are influenced by the surface temperature. The addition of boron to the black liquor, which debottlenecks the recausticizing plant by a reduction in lime usage, also influences the characteristics of black liquor combustion, such as combustion time and swelling. Previously, no effective measurement technique has been available to quantify sodium concentration in the plume of a burning black liquor droplet with or without boron, or to record the distribution of surface temperature through the time history of a burning droplet. This thesis reports on the adaptation of two techniques for the measurement of the release of atomic sodium and the temperature history, and their application to investigate several aspects of the release of atomic sodium during combustion of black liquor in a flat flame environment. The simultaneous employment of a planar laser-induced fluorescence (PLIF) technique with an absorption technique has been adapted to allow quantitative measurement of the release of atomic sodium. The absorption technique has been employed to correct for both fluorescence trapping due to absorption and attenuation by high concentration of the atomic sodium in the plume, and for collisional quenching by the other major gas components present in the flat flame. An independent assessment was performed using kinetic calculations, based on measured total sodium that is residual in a particle obtained at different stages in the combustion process. These independent assessments were used to provide greater insight in to the release process and to cross-check. The influence of both the initial diameter of the droplet and addition of boron to the black liquor on the temporal release and the release rate of atomic sodium during the combustion have been performed using the present PLIF technique. The second technique, two-dimensional two-colour optical pyrometry, has been adapted to measure the distribution of surface temperature and the swelling (change in surface area) of a burning black liquor droplet. The influence of surface temperature or the change in the external surface area of the droplet on the release of atomic sodium during the combustion of black liquor has been assessed through concurrent use of both adapted techniques. The highest concentration of atomic sodium was measured in the final stage of combustion that of smelt coalescence, where it is an order of magnitude greater than in the other stages combined. While the extensive release of atomic sodium at high temperature in this final combustion stage occurs in only a relatively small percentage of droplets in a kraft recovery boiler, the effect could still be significant in fume formation. This is because the extensive release is expected to occur in the very small droplets, predominantly generated by splitting or physical ejection. Small droplets will have a very short combustion time and so could remain in suspension within hot gases for sufficient time for extensive release of sodium. These measurements outcomes can be used to support the future development of sub-models for computational fluid dynamics (CFD) models in order to better understand and optimise fume formation in a kraft recovery boiler. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1474431 / Thesis (Ph.D.) - University of Adelaide, School of Mechanical Engineering, 2009

No description available.

The ongoing interest in bacterial interactions with various surfaces, followed by attachment and subsequent biofilm formation, has been driven by the importance of bacterial activities in number of medical, industrial and technological applications. However, bacterial adhesion to surfaces has not been completely understood due to the complexity of parameters involved. The study presented herein investigates the attachment pattern of nine medically and environmentally significant bacteria belonging to different taxonomic lineages: Firmicutes - Bacillus, Gammaproteobacteria, Alphaproteobacteria and Bacteriodetes. Physicochemical assessment techniques such as contact angle and surface charge measurements, atomic force microscopy (AFM), scanning electron microscopy (SEM), confocal microscopy (CLSM), as well as X-ray photoelectron spectroscopy (XPS), X-ray fluorescence spectroscopy (XRF) and time-of-flight secondary ion mass spectroscopy (ToF-SIMS) analysis were all employed in order to attain better insight into the factors that influence bacterial interactions with surfaces. Bacterial surface characteristics such as surface wettability and charge in addition to substratum surface wettability, tension, charge and chemistry were also considered. However due to the recent interest in designing micro-textured surfaces with antibacterial and/or antifouling effects the prime was given to the influence of micro- and nano-meter scale surface textures on bacterial adhesion. The interactions between selected bacteria and glass, polymer and optical fibre surfaces were studied. Carefully designed methods for surface modification allowed alteration of the topography of glass, polymer and optical fibre surfaces while maintaining other surface parameters near constant. This allowed isolated assessment of only the effects of surface roughness on bacterial adhesion. Obtained results indicated consistent cellular inclination towards the smoother surfaces for all of the tested species. Enhanced bacterial presence on the smoother surfaces was also accompanied by changes in the bacterial metabolic activity as indicated by the elevated levels of secreted extracellular polymeric materials (EPS) and modifications in the cells morphology. The results indicate that nano-scale surface roughness exert greater influence on bacterial adhesion than previously believed and should therefore be considered as a parameter of primary interest alongside other wellrecognized factors that control initial bacterial attachment.

viii, 178 leaves : ill., graphs ; 31 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, 1976

Thesis (PhD)--University of South Australia, 1999

Deposition of thin material films by sputtering is an increasingly common process in the field of silicon (Si)-based photovoltaics. One of the recently developed sputter-deposited materials applicable to Si photovoltaics comprises Si nanocrystals (NCs) embedded in a Si-based dielectric. The particular case of Si nanocrystals in a Silicon Dioxide (SiO2) matrix was studied by fabricating metal-insulator-semiconductor (MIS) devices, in which the insulating layer consists of a single layer of Si NCs in SiO2 deposited by sputtering (Si:NC-MIS devices). These test structures were subjected to impedance measurements. The presence of Si NCs was found to result in two distinct capacitance peaks. The first of these peaks is attributable to the small signal response of states at the insulator/substrate interface, enhanced by the presence of fixed charge associated with the NC layer. The second peak, which occurs without precedent, is due to external inversion layer coupling, in conjunction with a transition between tunnel-limited and semiconductor-limited electron current. Si:NC-MIS devices are also potential test structures for energy-selective contacts, based on SiO2/Si NC/SiO2 double barrier structures fabricated by sputtering. Using a one-dimensional model, current-voltage (I-V) curve simulations were performed for similar structures, in which the Si NCs are replaced by a Si quantum well (QW). The simulations showed that for non-degenerately doped Si substrates, the density of defects in the SiO2 layers can strongly influence the position of I-V curve structure induced by QW quasi-bound states. Passivation of crystalline Si (c-Si) surfaces by sputter-deposited dielectric films is another major application of sputtering for Si photovoltaics. This application was explored for the cases of sputtered SiO2 and hydrogenated Silicon Oxy-Carbide (SiOC:H). For the case of sputtered SiO2, an effective surface recombination velocity of 146 cm/s was achieved for an injection level of 1E15 cm???3. The investigated SiOC:H films were found to be unsuitable for surface passivation of Si, however their passivation performance could be slightly improved by first coating the Si surface with a chemically-grown or sputtered SiO2 layer. The investigations performed into specific aspects of sputter-deposited SiO2, Si NCs, and SiOC:H have highlighted important properties of these films, and confirmed the effectiveness of sputtering as a deposition technology for Si photovoltaics.

Doctor of Philosophy(PhD) / Digital photography has not only changed the nature of photography and the photographic process, but also the manner in which we share photographs and tell stories about them. Some traditional methods, such as the family photo album or passing around piles of recently developed snapshots, are lost to us without requiring the digital photos to be printed. The current, purely digital, methods of sharing do not provide the same experience as printed photographs, and they do not provide effective face-to-face social interaction around photographs, as experienced during storytelling. Research has found that people are often dissatisfied with sharing photographs in digital form. The recent emergence of the tabletop interface as a viable multi-user direct-touch interactive large horizontal display has provided the hardware that has the potential to improve our collocated activities such as digital photograph sharing. However, while some software to communicate with various tabletop hardware technologies exists, software aspects of tabletop user interfaces are still at an early stage and require careful consideration in order to provide an effective, multi-user immersive interface that arbitrates the social interaction between users, without the necessary computer-human interaction interfering with the social dialogue. This thesis presents PhoTable, a social interface allowing people to effectively share, and tell stories about, recently taken, unsorted digital photographs around an interactive tabletop. In addition, the computer-arbitrated digital interaction allows PhoTable to capture the stories told, and associate them as audio metadata to the appropriate photographs. By leveraging the tabletop interface and providing a highly usable and natural interaction we can enable users to become immersed in their social interaction, telling stories about their photographs, and allow the computer interaction to occur as a side-effect of the social interaction. Correlating the computer interaction with the corresponding audio allows PhoTable to annotate an automatically created digital photo album with audible stories, which may then be archived. These stories remain useful for future sharing -- both collocated sharing and remote (e.g. via the Internet) -- and also provide a personal memento both of the event depicted in the photograph (e.g. as a reminder) and of the enjoyable photo sharing experience at the tabletop. To provide the necessary software to realise an interface such as PhoTable, this thesis explored the development of Cruiser: an efficient, extensible and reusable software framework for developing tabletop applications. Cruiser contributes a set of programming libraries and the necessary application framework to facilitate the rapid and highly flexible development of new tabletop applications. It uses a plugin architecture that encourages code reuse, stability and easy experimentation, and leverages the dedicated computer graphics hardware and multi-core processors of modern consumer-level systems to provide a responsive and immersive interactive tabletop user interface that is agnostic to the tabletop hardware and operating platform, using efficient, native cross-platform code. Cruiser's flexibility has allowed a variety of novel interactive tabletop applications to be explored by other researchers using the framework, in addition to PhoTable. To evaluate Cruiser and PhoTable, this thesis follows recommended practices for systems evaluation. The design rationale is framed within the above scenario and vision which we explore further, and the resulting design is critically analysed based on user studies, heuristic evaluation and a reflection on how it evolved over time. The effectiveness of Cruiser was evaluated in terms of its ability to realise PhoTable, use of it by others to explore many new tabletop applications, and an analysis of performance and resource usage. Usability, learnability and effectiveness of PhoTable was assessed on three levels: careful usability evaluations of elements of the interface; informal observations of usability when Cruiser was available to the public in several exhibitions and demonstrations; and a final evaluation of PhoTable in use for storytelling, where this had the side effect of creating a digital photo album, consisting of the photographs users interacted with on the table and associated audio annotations which PhoTable automatically extracted from the interaction. We conclude that our approach to design has resulted in an effective framework for creating new tabletop interfaces. The parallel goal of exploring the potential for tabletop interaction as a new way to share digital photographs was realised in PhoTable. It is able to support the envisaged goal of an effective interface for telling stories about one's photos. As a serendipitous side-effect, PhoTable was effective in the automatic capture of the stories about individual photographs for future reminiscence and sharing. This work provides foundations for future work in creating new ways to interact at a tabletop and to the ways to capture personal stories around digital photographs for sharing and long-term preservation.