Automotive engineering metal foam structures: fabrication, characterisation, testing and simulation

The contrubution of this thesis is to generate fundamental research and design information on the impact and bending behaviours of metal foams and foam-filled tubes

Characterization of the moisture absorption and thermal ageing behaviour of polymeric composite systems using Raman spectroscopy

Advanced polymeric materials and their respective composites are fast becoming one of the world's most frequently used engineering materials. They find application in the manufacture of e.g. boat hulls, high performance motor vehicles, aircraft components and sports goods. Their high specific strength and specific stiffness give them the edge in applications where weight savings are critical, but their long-term durability is often questioned. These materials are susceptible to environmental conditions such as temperature and humidity. There is also a lack of relevant data, due to the long time-scales required for testing. In this study, the Raman technique has been used to monitor the degradation of two composite systems, namely: a rubber toughened vinylester material used in the marine industry and a high temperature bismaleimide/carbon fibre aerospace composite. Preliminary Raman studies show that the toughening rubber particles dispersed in the cured vinylester resin are leached out during hygrothermal ageing. The weight gain during ageing suggests that this leaching process occurs concurrently with the absorption of water molecules. An increase in the degree of cross-linking is observed when bismaleimide/carbon fibre composite is aged at high temperature. This cross- linking tendency decreases with increasing depth within the carbon fibre bundle.

Absorption and desorption characteristics of fluoride in the calcareous and siliceous sand sheet aquifers of south-west Victoria, Australia

This study assessed the sustainability of utilising groundwater systems to
manage an aluminium smelter's fluoridated trade wastewater stream. Replacing ocean discharge of the wastewater with land irrigation is one option. Using a groundwater model (developed using MODFLOW incorporating parameter estimation software (PEST-ASP)), we found that most of the groundwater flow takes place through surface sands. Fluoride is adsorbed in these sands during the drier summer months, but desorption is rapid when winter rain flushes the aquifer. Underlying clays and other layers prevent significant contamination of the deeper aquifer.

Incorporation of fused tetrathiafulvalenes (TTFs) into polythiophene architectures : varying the electroactive dominance of the TTF species in hybrid systems

A novel polythienylenevinylene (PTV) and two new polythiophenes (PTs), featuring fused tetrathiafulvalene (TTF) units, have been prepared and characterized by ultraviolet−visible (UV−vis) and electron paramagnetic resonance (EPR) spectroelectrochemistry. All polymers undergo two sequential, reversible oxidation processes in solution. Structures in which the TTF species is directly linked to the polymer backbone (2 and 4) display redox behavior which is dictated by the fulvalene system. Once the TTF is spatially removed from the polymer chain by a nonconjugated link (polymer 3), the electroactivity of both TTF and polythiophene moieties can be detected. Computational studies confirm the delocalization of charge over both electroactive centers (TTF and PT) and the existence of a triplet dication intermediate. PTV 4 has a low band gap (1.44 eV), is soluble in common organic solvents, and is stable under ambient conditions. Organic solar cells of polymer 4:[6,6]-phenyl-C₆₁ butyric acid methyl ester (PCBM) have been fabricated. Under illumination, a photovoltaic effect is observed with a power conversion efficiency of 0.13% under AM1.5 solar simulated light. The onset of photocurrent at 850 nm is consistent with the onset of the π−π absorption band of the polymer. Remarkably, UV−vis spectroelectrochemistry of polymer 4 reveals that the conjugated polymer chain remains unchanged during the oxidation of the polymer.

Predicting the acceptance of unit guide information systems

Information Systems can play an important role in ensuring and improving the quality of education provided. However, lack of acceptance of these information systems and resistance of technology innovations by the end users limit the expected benefits of the system. This research attempts to identify the key determinants for the acceptance of the Unit Guide Information Systems (UGIS) in the Australian higher education sector. The technology acceptance model (TAM), social cognitive theory (SCT) and model of PC utilization (MPCU) are combined to provide a new framework for this analysis. Results of the study are consistent with the technology acceptance factors for explaining the behavioural intention of the academics. The study also shows the effects of application specific self-efficacy, application specific anxiety and social influence on the acceptance of UGIS. Implications of the results are discussed within the context of unit guides and curriculum mapping.

Surface structure of SnOxNy thin films deposited using a filtered cathodic arc for novel energy storage systems

Tin oxide/nitride (SnOxNy) thin films were synthesised using a filtered cathodic vacuum arc deposition system. These films were deposited at room temperature with increasing amounts of reactive nitrogen gas to alter the nanostructure. To understand the surface structure of the coatings several techniques were used including scanning electron microscopy (SEM), atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS), x-ray diffraction (XRD) and x-ray absorption spectroscopy (XAS). Preliminary results have shown that a cathodic arc can be used to deposit smooth films which exhibit a mixed tin oxide/nitride structure.

Enhancement of transient stability limit and voltage regulation with dynamic loads using robust excitation control

In stressed power systems with large induction machine component, there exist undamped electromechanical modes and unstable montonic voltage modes. This article proposes a sequential design of an excitation controller and a power system stabiliser (PSS) to stabilise the system. The operating region, with induction machines in stressed power systems, is often not captured using a linearisation around an operating point, and to alleviate this situation a robust controller is designed which guaruntees stable operation in a large region of operation. A minimax linear quadratic Gaussian design is used for the design of the supplementary control to automatic voltage regulators, and a classical PSS structure is used to damp electromechanical oscillations. The novelty of this work is in proposing a method to capture the unmodelled nonlinear dynamics as uncertainty in the design of the robust controller. Tight bounds on the uncertainty are obtained using this method which enables high-performance controllers. An IEEE benchmark test system has been used to demonstrate the performance of the designed controller

Kinetic resolution of the interactions between agrochemical products and adjuvant systems upon mixing

The addition of an adjuvant to a pesticide usually occurs in a mix-tank, before spray application to the crop. Their interaction is potentially crucial to overall efficacy but has received little attention from a physical-chemical perspective. Study was undertaken by laser diffraction, Raman spectroscopy, and small-angle X-ray scattering to resolve these physical processes. It was shown that migration of the pesticide into the adjuvant droplet occurred in all cases studied. The level of transfer was dependent upon adjuvant level, adjuvant solubility, and surfactant level. For suspension pesticides, dissolution of crystallites within the droplet occurred to a degree limited by solubility. The results directly demonstrate the transfer of the pesticide into the adjuvant carrier. This indicates that for emulsion-based pesticides, application to the target is likely as a homogeneously mixed droplet, whereas for suspension pesticides, solubility may limit transfer and dissolution, leading to heterogeneity in the applied particles.