Zigbee is a relatively new wireless mesh networking standard with emphasis on low cost and energy conservation. It is intended to be used in wireless monitoring and control applications such as sensors and remotely operated switches where the end devices are battery powered. Because it is a recent technology there is not sufficient understanding on how network architecture and configuration affect power consumption of the battery powered devices. This research investigates the power consumption and delivery ratio of Zigbee wireless mesh and star networks for a single sink real time monitoring system at varying traffic rates and the beacon and non beacon mode operation of its underlying standard IEEE 802.15.4 in the star network architecture. To evaluate the performance of Zigbee, the network operation was simulated using the simulation tool NS-2. NS-2 is capable of simulating the entire network operation including traffic generation and energy consumption of each node in the network. After first running the simulation it was obvious that there were problems in the configuration of the simulator as well as some unexpected behaviour. After performing several modifications to the simulator the results improved significantly. To validate the operation of the simulator and to give insight on the operation of Zigbee, a real Zigbee wireless network was constructed and the same experiments that were conducted on the simulator were repeated on the Zigbee network. The research showed that the modified simulator produced good results that were close to the experimental results. It was found that the non beacon mode of operation had the lowest power consumption and best delivery ratio at all tested traffic rates. The operation of Zigbee mesh and star networks were compared to the results for IEEE 802.15.4 star networks in non beacon mode which revealed that the extra routing traffic sent by the Zigbee networking layers does contribute significantly to the power consumption, however even with the extra routing traffic, power consumption is still so low that it the battery life of the device would be limited by the shelf life of the battery, not by the energy consumption of the device. This research has successfully achieved its objectives and identified areas for future development. The simulator model for NS-2 could be improved to further increase the accuracy of the results as well as include the Zigbee routing layers and the experimental results could be improved by a more accurate power consumption data acquisition method.

The contributions of this thesis are an implicit modelling method for the coupled constitutive relations and an energy-based method for material modelling. The two developed methods utilise implicit models to represent material constitutive relations without the requirement of physical parameters. The first method is developed to model coupled constitutive relations using state-space representation with neural networks. State-space representation is employed to express the desired relations in a compact fashion while simultaneously providing the capability of modelling rate- and/or path-dependent behaviour. The employment of neural networks with the generalised state-space representation results in a single implicit model that can be adapted for a broad range of constitutive behaviours. The performance and applicability of the method are highlighted through the applications for various constitutive behaviour of piezoelectric materials, including the effects of hysteresis and cyclic degradation. An energy-based method is subsequently developed for implicit constitutive modelling by utilising the energy principle on a deformed continuum. Two formulations of the proposed method are developed for the modelling of materials with varying nature in directional properties. The first formulation is based on an implicit strain energy density function, represented by a neural network with strain invariants as input, to derive the desired stress-strain relations. The second formulation consists of the derivation of an energy-based performance function for training a neural network that represents the stress-strain relations. The requirement of deriving stress is eliminated in both formulations and this facilitates the use of advanced experimental setup, such as multi-axial load tests or non-standard specimens, to produce the most information for constitutive modelling from a single experiment. A series of numerical studies -- including validation problems and practical cases with actual experimental setup -- have been conducted, the results of which demonstrate the applicability and effectiveness of the proposed method for constitutive modelling on a continuum basis.

This thesis investigates several different aspects of the physics of few state quantum systems and their use in information processing applications. The main focus is performing high precision computations or experiments using imperfect quantum systems. Specifically looking at methods to calibrate a quantum system once it has been manufactured or performing useful tasks, using a quantum system with only limited spatial or temporal coherence. / A novel method for characterising an unknown two-state Hamiltonian is presented which is based on the measurement of coherent oscillations. The method is subsequently extended to include the effects of decoherence and enable the estimation of uncertainties. Using the uncertainty estimates, the achievable precision for a given number of measurements is computed. This method is tested experimentally using the nitrogen-vacancy defect in diamond as an example of a two-state quantum system of interest for quantum information processing. The method of characterisation is extended to higher dimensional systems and this is illustrated using the Heisenberg interaction between spins as an example. / The use of buried donors in silicon is investigated as an architecture for realising quantum-dot cellular automata as an example of quantum systems used for classical information processing. The interaction strengths and time scales are calculated and both coherent and incoherent evolution are assessed as possible switching mechanisms. The effects of decoherence on the operation of a single cell and the scaling behaviour of a line of cells is investigated. / The use of type-II quantum computers for simulating classical systems is studied as an application of small scale quantum computing. An algorithm is developed for simulating the classical Ising model using Metropolis Monte-Carlo where random number generation is incorporated using quantum superposition. This suggests that several new algorithms could be developed for a type-II quantum computer based on probabilistic cellular automata.

As an outcome of very active arbovirus monitoring programs that began in Australia in the 1950s, some of the most diverse and unusual rhabdoviruses in the world have been isolated from this continent. These novel rhabdoviruses represent an important and valuable pool of highly diverse viruses; however, most of them have remained poorly characterised. In light of the significant disease potential of numerous rhabdoviruses, the characterisation of novel rhabdoviruses is indispensable for threat assessment to livestock, wildlife and humans and preparedness for outbreaks. The genetic characterisation of novel viruses is also an essential step for the development of molecular detection assays for improved monitoring and investigations into unidentified disease cases. In this study, the complete genomes of four novel rhabdoviruses have been sequenced and a fifth is close to completion. The substantial new data generated has significantly extended the understanding of the biology and evolution of the Rhabdoviridae. Wongabel virus (WONV), isolated from the biting midge Culicoides austropalpalis, was found to contain a unique genome structure encoding ten genes, including five novel genes (Chapter 2). Analysis by western blotting suggested that four out of the five novel genes were expressed in infected cell cultures. Ngaingan virus (NGAV), isolated from Culicoides brevitarsis, was found to have the largest genome of any rhabdovirus sequenced to date, and with thirteen genes has the largest number of genes of any (-) ssRNA virus sequenced to date (Chapter 3). Seven of the thirteen genes are novel. Similar to viruses in the genus Ephemerovirus (bovine ephemeral fever virus and Adelaide River virus), NGAV contains a second glycoprotein with an unknown function. Phylogenetic analysis places this virus alongside WONV and the north-American bird and mosquito-associated Flanders virus within the Hart Park group that remains to be classified by the ICTV. Screening of various wildlife and livestock sera collected in northern Australia indicated a strong association of NGAV with macropods. Tibrogargan virus (TIBV) and Coastal Plains virus (CPV) were isolated from cattle and Culicoides brevitarsis (TIBV). Past serological surveys reported both viruses to be highly prevalent in cattle in northern Australia and demonstrated that the two viruses share a relatively close relationship at the antigenic level. The genomic analyses revealed that these two viruses have a unique genome organization, with three additional genes (Chapter 4). These additional genes are highly diverged at the sequence level but the encoded putative proteins share a significant conservation of secondary structure elements. The sequencing of these two related viruses has provided a unique opportunity to gain insights into the characteristics and evolution of novel proteins in two different rhabdoviruses. Phylogenetic analyses showed that TIBV and CPV form an independent cluster which does not appear to belong to any of the current genera, but which is most closely related to the genus Ephemerovirus based on N protein analysis. Although neither virus has been associated with disease, a serological survey of various animal sera collected in northern Australia showed that these viruses are currently highly prevalent in sentinel cattle and buffalo. Oak Vale virus (OVRV) was isolated from mosquitoes, Culex edwardsi and Ochlerotatus vigilax, from two geographically diverse regions of Australia located approximately 3000 km apart. The genome of OVRV was found to contain only one novel gene (Chapter 5). Comparatively, the genome of this virus is much less complex than the others in this study, but this virus displays considerable divergence from all other rhabdoviruses. A high seroprevalence for this virus was found in the feral pig population in northern Australia. The data generated from this study represents a considerable increase in the quantity of genetic data available for this viral family, and has revealed the existence of a large number of previously unidentified genes, highlighting that that the potential for complexity within the prototype genomic model of a rhabdovirus is much greater than previously thought. The novel nature of the additional genes provides grounds for further research into rhabdovirus evolution. Analysis of this new data suggests that these viruses cannot be classified into existing genera under the current criteria and it is clear that the taxonomy of the Rhabdoviridae requires revision. The observation that these viruses are currently circulating in livestock and wildlife in northern Australia accentuates the need for closer monitoring of animals and the need for further study of this diverse and fascinating group of viruses.

Zigbee is a relatively new wireless mesh networking standard with emphasis on low cost and energy conservation. It is intended to be used in wireless monitoring and control applications such as sensors and remotely operated switches where the end devices are battery powered. Because it is a recent technology there is not sufficient understanding on how network architecture and configuration affect power consumption of the battery powered devices. This research investigates the power consumption and delivery ratio of Zigbee wireless mesh and star networks for a single sink real time monitoring system at varying traffic rates and the beacon and non beacon mode operation of its underlying standard IEEE 802.15.4 in the star network architecture. To evaluate the performance of Zigbee, the network operation was simulated using the simulation tool NS-2. NS-2 is capable of simulating the entire network operation including traffic generation and energy consumption of each node in the network. After first running the simulation it was obvious that there were problems in the configuration of the simulator as well as some unexpected behaviour. After performing several modifications to the simulator the results improved significantly. To validate the operation of the simulator and to give insight on the operation of Zigbee, a real Zigbee wireless network was constructed and the same experiments that were conducted on the simulator were repeated on the Zigbee network. The research showed that the modified simulator produced good results that were close to the experimental results. It was found that the non beacon mode of operation had the lowest power consumption and best delivery ratio at all tested traffic rates. The operation of Zigbee mesh and star networks were compared to the results for IEEE 802.15.4 star networks in non beacon mode which revealed that the extra routing traffic sent by the Zigbee networking layers does contribute significantly to the power consumption, however even with the extra routing traffic, power consumption is still so low that it the battery life of the device would be limited by the shelf life of the battery, not by the energy consumption of the device. This research has successfully achieved its objectives and identified areas for future development. The simulator model for NS-2 could be improved to further increase the accuracy of the results as well as include the Zigbee routing layers and the experimental results could be improved by a more accurate power consumption data acquisition method.

The oxidation and ignition behaviour of the four major sulfide minerals present in the nickel concentrates smelted at the Kalgoorlie Nickel Smelter (KNS) has been established. These minerals are pyrite (FeS2), pyrrhotite (Fe1-nS, where n = 0 to 0.125), pentlandite ((FeNi)9S8) and violarite ( Ni2FeS4 ).The characteristic behaviour of these sulfides has been examined using Thermogravimetry-Differential Thermal Analysis (TG-DTA) under normal oxidation conditions ( l0ºC/min, air atmosphere). By increasing the heating rate to 40ºC/min and using an oxygen atmosphere, the tendency of the sulfides to ignite was established. Ignition was characterised by a highly exothermic reaction which occurred in association with a rapid mass loss over a short time span. Significant overheating of the samples beyond the temperature of the surroundings was observed. Pyrite, pyrrhotite and violarite all exhibited ignition behaviour while pentlandite did not.Using Isothermal Thermogravimetry (TG) the sulfides were subjected to shock heating conditions (heating rate = 3000-5000ºC/min, oxygen atmosphere) analogous to those which exist in an industrial flash smelter. The order of reactivity of the sulfides agreed with that observed during TG-DTA ignition trials. Even under these more intensely oxidising conditions pentlandite did not ignite. The effect of particle size on the ignition temperature was determined, larger particles igniting at a higher temperature. The magnitude of this effect varied according to the characteristics of the minerals.Products collected during Isothermal TG were examined by optical microscopy, Scanning Electron Microscopy (SEM) and Electron Probe Microanalysis (EPMA). Using these techniques it was possible to establish the morphology of the products and hence, to propose mechanisms for the reaction of the four sulfide minerals under ignition conditions.In order to ++ / simulate the thermal environment which exists in the KNS, a pilot scale model of the reaction shaft was used. Nickel sulfide concentrates of varying mineralogy and particle size distribution were smelted under various conditions. The effect of larger particle size and increasing oxygen partial pressure on the reactivity of these concentrates was established.The products were quenched at the base of the shaft and collected for examination by optical microscopy, SEM and EPMA. Products ranged from unreacted to completely oxidised particles. The morphology and composition of these species were identified. Approximately 30 particles in each of 26 samples were examined with a view to establishing the frequency of occurrence of the particular product types in concentrates of differing mineralogy and particle size. This allowed proposals to be made regarding the fate of the individual sulfide minerals during ignition in the pilot scale flash reactor.

It is essential to make performance measurements of photovoltaics modules in order to quantify the power they will produce under operational conditions. Performance measurements are fundamental throughout the photovoltaic industry, from product development to quality control in manufacturing and installation in the field. Rapid and economic evaluation of photovoltaic performance requires measurements using pulsed illumination solar simulators. However some devices have characteristics which can cause difficulties making these measurements. The aim of this thesis is to overcome these measurement problems focusing particularly on two of the most prevalent and pressing of these problematic characteristics: high capacitance and metastability. A new method for measuring high capacitance modules in a pulsed simulator, based on tailor made voltage ramps, was developed. The voltage ramp is tailor made such that the measurement time is minimised while maintaining high accuracy (0.5 %), allowing the measurement of high capacitance modules in a single 10ms illumination pulse. The necessary inputs for this method are the capacitance and dark current as a function of voltage for each module. In order to make these measurements, at the high forward bias voltages required, a new system was developed. The tailored voltage ramp can be created individually for each module, since the process is rapid an automatic. This makes the method applicable to a production line or to test house measurements. In addition to their use as inputs for the voltage ramp design, the capacitance and dark current also contain other valuable information, including effective minority carrier lifetime. In several thin film technologies, such as CIGS, the efficiency is not a fixed value, rather the module is metastable and the efficiency changes depending on the previous exposure /preconditioning of the device. Preconditioning is normally applied to these devices before measurement in order to put them in a specific state that is repeatable and representative of outdoor operation. Improved preconditioning practices are vital for performance measurements in CIGS modules. Therefore the preconditioning behaviour of a variety of CIGS modules from different manufacturers was investigated. The effect of preconditioning varied for different modules, commonly the fill factor improved substantially, but often changes in open circuit voltage were also seen and in some cases also substantial changes in short circuit current. The rates of preconditioning and relaxation were found to follow stretched exponential behaviour, such that the changes occur linearly on a logarithmic timescale over several orders of magnitude in time. The total time for performance stabilisation was found to vary significantly between different types of module. Because of this stretched exponential behaviour, even though the module took days to fully relax to the dark state, there was significant relaxation within the tens of minutes that it would normally take a module to cool down after light soaking before it could be measured. The major implication of observed kinetics is that in order to achieve repeatable measurement the timing in each element of a preconditioning routine should be controlled such that the fractional error in the duration of each step is small. During the investigation an unexpectedly short timescale preconditioning effect was observed, which occurs on a millisecond timescale and relaxes in seconds. It was shown that the measurement artefacts introduced using this method can be eliminated by using electrical forward bias until immediately before the measurement. Another measurement system was developed to track the dark current and C-V characteristic of the modules during electrical bias preconditioning and subsequent relaxation. These measurements demonstrate that more than one process involved during preconditioning in CIGS. Changes occur both in the doping in the bulk of the absorber and also in charge accumulation occurring near to the absorber / buffer interface. The theoretical models for preconditioning in CIGS were reviewed and compared to the experimental results. A rate model was developed based on the theory of the metastable VSe-VCu defect. This model was shown to correspond well to the rates of preconditioning and relaxation in CIGS. The non-exponential behaviour was shown to be compatible with a distribution of activation energies for the transition between different defect states. The difference in the time taken for modules to stabilise is explained by differences in doping density and the density of VSe-VCu defects. The work presented facilitates more accurate, economical performance measurements for high capacitance devices and CIGS devices, thereby contributing to the large scale implementation of photovoltaics as power source.

We investigate the some of the many subtleties in taking a microscopic approach to modelling the decoherence of an Open Quantum System. We use the RF-SQUID, which will be referred to as a simply a SQUID throughout this paper, as a non-linear example and consider different levels of approximation, with varied coupling, to show the potential consequences that may arise when characterising devices such as superconducting qubits in this manner. We first consider a SQUID inductively coupled to an Ohmic bath and derive a Lindblad master equation, to first and second order in the Baker-Campbell-Hausdorff expansion of the correlation-time-dependent flux operator. We then consider a SQUID both inductively and capacitively coupled to an Ohmic bath and derive a Lindblad master equation to better understand the effect of parasitic capacitance whilst shedding more light on the additions, cancellations and renormalisations that are attributed to a microscopic approach.

Graphene-based materials (GBM) have recently generated great interest due to their unique two-dimensional (2D) carbon geometry, which confers exceptional physicochemical properties that hold great promise in many fields, including biomedicine. An understanding of how these novel 2D materials interact with the biological milieu is therefore fundamental for their development and use. Graphene oxide (GO) has been proven more biologically friendly than the highly hydrophobic pristine graphene. Therefore, the main aim of this study was to prepare well-characterised GO derivatives and test the hypothesis of their possible use for biomedical applications. GO was prepared reproducibly by a modified Hummers' method and further functionalised by using a radio-metal chelating agent, namely 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA) to form GO-DOTA. The constructs were extensively studied using structural, optical and surface characterisation techniques. GO prepared from different forms of graphite demonstrated differences mainly in structure and production yields. However, all GO constructs were found biocompatible, with the mammalian cell cultures tested; furthermore, the biocompatibility of GO prepared as papers was retained when they were used as substrates for cell growth. Radiolabelling of GO-DOTA was further carried out to yield highly stable radio-labelled constructs, both in vitro and in vivo. These constructs were used for in vivo whole-body imaging and biodistribution studies in mice after intravenous administration. Extensive urinary excretion and accumulation mainly in the reticuloendothelial system (RES), including the spleen, liver and lungs, was the main fate of all the GO derivatives used in this thesis. The physicochemical characteristics were determined to play a central role for their preferential fate and accumulation. While the thicker sheets tended to accumulate mainly in the RES, the thinner ones were mostly excreted via the kidneys. Finally, it was crucial to perform safety investigations involving the structure and function of organs at high risk of injury (mainly the kidney and spleen). Our results revealed that no severe structural damage or histopathologic or functional abnormality of these vital organs. However, some preliminary inflammatory responses were detected that require further investigation. In summary, this study helped gain a better understanding of how thin 2D materials interact with biological barriers and the results indicate that these materials could be potential candidates for biological applications. Nevertheless, further investigations are necessary to confirm our findings.

Over the last five years hybrid organic-inorganic metal halide perovskites have attracted strong interest in the solar cell community as a result of their high power conversion efficiency and the solid opportunity to realise a low-cost as well as industry-scalable technology. Nevertheless, several aspects of this novel class of materials still need to be explored and the level of our understanding is rapidly and constantly evolving, from month to month. This dissertation reports investigations of perovskite solar cells with a particular focus on their local chemical composition. The analytical characterisation of such devices is very challenging due to the intrinsic instability of the organic component in the nanostructured compounds building up the cell. STEM-EDX (Scanning Transmission Electron Microscopy - Energy Dispersive X-ray spectroscopy) was employed to resolve at the nanoscale the morphology and the elemental composition of the devices. Firstly, a powerful procedure, involving FIB (Focus Ion Beam) sample preparation, the acquisition of STEM-EDX maps and the application of cutting edge post-processing data techniques based on multivariate analysis was developed and tested. The application of this method has drastically improved the quality of the signal that can be extracted from perovskite thin films before the onset of beam-induced transformations. Morphology, composition and interfaces in devices deposited by using different methodologies and external conditions were then explored in detail by combining multiple complementary advanced characterisation tools. The observed variations in the nanostructure of the cells were related to different photovoltaic performance, providing instructive indications for the synthesis and fabrication routes of the devices. Finally, the main degradation processes that affect perovskite solar cells were probed. STEM-EDX was used in conjunction with the application of in situ heating, leading to the direct observation of elemental species migration within the device, reported here for the first time with nanometric spatial resolution. Further analyses, involving a set of experiments aimed to study the effects of air exposure and light soaking on the cells, were designed and performed, providing evidence of the main pathways leading to the drastic drop in the device performance.