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(2010)ThesisThe aim of this thesis was to investigate the chemical processes involved in the production and transformation of the major acid sulfate soil (ASS) contaminants, iron (Fe) and aluminium (AI), and their associated acidity, as they are transported from the soil to coastal waters. The results of these investigations are summarised below. Within the body of the thesis, the results are discussed in relation to currently available remediation options aimed at reducing the export of these contaminants to neighbouring estuaries. Laboratory studies established that high concentrations of dissolved silica (Si) and natural organic matter (NOM) present in coastal lowland acid sulfate soil (CLASS) groundwaters inhibit the Fe(II)-catalysed transformation of poorly crystalline Fe(Ill) minerals to thermodynamically stable Fe(III) minerals. This is consistent with CLASS environments being dominated by Fe(I]I) minerals that readily undergo reductive dissolution. The release of soluble AI from the soil profile was found to be highly pH dependent. Solid phase and theoretical solubility calculations indicate the solubility of AI within CLASS groundwaters above approximately pH 4.5 is most likely controlled by the formation of a mixture of amorphous basaluminite (AI4(OH)J(..~D4.4H20) and AI(OH)3' Basaluminite is also predicted to be the major species controlling the solubility of Al at the interface of the CLASS flood drains and pH 6-8 buffered estuarine waters. Chemical Transformations of Fe and AI from Acid Sulfate Soils to Coastal Waters Abstract Laboratory studies indicated that dissolved NOM-facilitated transport of Fe(III) or Al(III) is not a significant transport pathway in CLASS environments. For Fe(III), this is due to NOM concentrations limiting the concentration of soluble Fe(III)-NOM complexes which may form. In the case of Al(III), AI(III)-NOM complexes formed were found to readily dissociate, thereby limiting the ability for dissolved NOM to transport significant concentrations of Al(III) large distances off-site. The concentration of sulfate within ASS discharge waters was also found to severely limit the potential for the highly toxic inorganic polymeric Al13 species to form. Field and laboratory studies demonstrate the photo-reduction potential of both dissolved and colloidal Fe(III) within the flood drains. This aids in maintaining higher concentrations of soluble Fe(II) than would otherwise be present in the absence of sunlight, increasing the transport of Fe to the main estuary. Laboratory studies also ascertained the degree to which SRFA catalyses the oxidation of Fe(II) at pH 3-5. A kinetic model encompassing the Fenton cycle, precipitation and catalysed Fe(II) oxidation satisfactorily modelled field results and identified the main chemical transformations of Fe occurring within the acidic flood drains.
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(2010)ThesisThis study develops computation models to examine impacts of telecommuting on transport systems and environment for both macro and micro levels. Models have been developed as tools to analyse transport policy and transport control systems relating to telecommuting. For transport policy development, four performance evaluation models have been attempted to examine the reduction of traffic congestion, vehicle-km travelled, travel time and pollution of transport networks. These computation models are developed consistent with empirical data from the literature for the aggregate assessments. In this thesis these models are called macro-level assessment models. For operation and control, a model to determine changes of flow pattern by telecommuting is proposed. This model applies traffic engineering theory referred to as the network equilibrium problem. This model accounts for impacts at road link level and it is called the micro-level assessment model. This study also proposed a definition and a classification of telecommuting to serve the development of models mentioned above. The proposed definition is presented by the precise approach and the approach based on characteristics of telecommuting. A new classification is necessary due to impacts of full-day and part-day telecommuting on transport and environment being different. The proposed classification distinguishes between full-day and part-day telecommuting instead of full time and part time telecommuting as in previous studies. This framework is applied to develop computational models. Numerical examples of the macro-level assessment models are demonstrated for data of New South Wales and Ho Chi Minh City. The average numerical magnitude estimated is about 7% for the reduction of traffic congestion in Ho Chi Minh City. The reduction of vehicle-km travelled in New South Wales is forecasted to be from 11% to 15.5% and the maximum saving of travel time would reach to II% in 2021. A numerical example of 8 nodes and 13 links of the micro-level assessment model is demonstrated. This is implemented via software program GAMS. Travel time saved because of changes of link flows in the trial network with telecommuting is estimated to be about 27.5%.
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(2010)ThesisEndocrine disrupting chemicals in the environment are widely implicated as a major cause of physiological abnormality in wildlife. Thus, it is crucial to better understand the fate and behaviour of potent endocrine disruptors, such as 17β-estradiol (E2), estrone (El) and ethinylestradiol (EE2). This research study has: (a) Developed assays for identifying estrogens in environmental matrices; (b) Determined estrogenic activity in aqueousand solidphasesofprimary,secondaryandtertiarysewagetreatment plants (STPs); and (c) Determined sorption behaviour of estrogens in wastewater and receiving environments. The development of solid phase and liquid extraction methods, coupled to gas chromatography-mass spectrometry, has enabled detection and quantification of low-level estrogens in STPs. Removal efficiency of Hand E2 from wastewater in primary STPs was poor (~14% and ~4% respectively). Secondary treatment removed significantly greater El and E210ads (~85% and ~96%) and these were further reduced folloWing tertiary treatment to below limit of Quantification (<0.1 ng.L-1) EE2 was <0.1 ng.L-1 in all tested wastewater samples. Secondary biosolids contained low-level estrogens, e.g., 9% Hand 1% E2 in waste activated sludge. EE2 also occurred at detectable levels in sludge. Suspended fine particulates in wastewater contained H , E2 and EE2, although actual levels varied between raw and treated effluent. Addition of NaCI caused particle aggregation and reduced levels of suspended estrogens in wastewater (containing 12% particles ≤1.5µm). Marine sediments near STP ocean outfall had 0.16-1.17 El, 0.22-2.48 E2 and <0.5 EE2 (ng/g). Estrogens removal via secondary treatment is controlled by preferential partitioning to the solid phase, due to high solid content in wastewater and extensive contact time between pollutants and sludge. Removal rates during activated sludge treatment are mainly caused by both sorption and degradation. The inefficiency of primary treatment is attributed to preferential partitioning to the water phase. Estrogens are not fully dissolved in waste water but are partially sorbed to fine particulates possessing colloidal characteristics; the high-strength ionic environment causes coagulation and aggregation of colloidal estrogens. Treated effluent released to marine waters undergoes particle aggregation, leading to eventual accumulation of estrogens in marine sediments. Modelling of the physico-chemical properties of estrogens provided generally robust predictions of their fate and behaviour, although results were inconsistent for biological treatments.
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(2010)ThesisThis dissertation demonstrates the applicability of the spaceborne interferometric synthetic aperture radar (InSAR) technique for measuring the ground surface displacement at various temporal and spatial scales. The dissertation focuses on optimisation of the InSAR technique for ground deformation monitoring applications due to earthquakes, underground mining, and groundwater extraction activities. There are four main factors which have limited the use of InSAR techniques for ground surface displacement monitoring. These four factors have been discussed and investigated in this dissertation, namely: (1) temporal and spatial decorrelation, (2) phase discontinuity due to rapid deformation, (3) atmospheric disturbances, and (4) retrieval of the 3D deformation vector. SAR satellite missions with longer radar wavelength, higher incident angle and finer ground imaging resolution are preferred in order to minimise the impact of the first two limitations. An approach has been developed and implemented to address the third limitation using small-stack SAR interferograms. Investigations to the fourth limitation have been carried out using InSAR pairs acquired from different viewing geometries to map the displacement due to underground mining in three dimensions. Persistent Scatterer Interferometry (PSI) is a SAR analysis technique which utilises long time series of interferometric SAR image data. A modified PSI technique has been proposed in this dissertation to enhance the utility of the conventional PSI technique. The main features of the proposed technique are: (1) improvement in the estimation and removal of orbital error and atmospheric error components, (2) improvement in the precision of PS point identification and the displacement estimated from the less reliable PS candidates, and (3) maximisation of total PS point identified while preserving accuracy. The capability of the proposed technique for urban subsidence monitoring has been demonstrated using both ENVISAT ASAR data and ALOS PALSAR data over Beijing City, China. Cross-validation has been carried out between the results obtained from both datasets. Good correlations have been observed from the PSI results from both datasets. The ENVISAT ASAR results showed good agreement with the continuous GPS measurements. The line-of-sight displacement rates derived from the results generated by both datasets were used to derive the vertical and horizontal displacement rates.
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(2010)ThesisMuch of the research into multipath detection and mitigation has not considered the carrier phase delay between the line of sight (LOS) and reflected signals. A novel parameter referred to as Early Late Phase (ELP) is proposed in this thesis to exploit this phase difference and the resultant shift in energy from the I to the Q channel of a receiver. ELP is calculated as a phase difference between early and late correlator outputs. ELP has a higher magnitude in the presence of multipath and thus is proposed for multipath detection. Since ELP exploits the carrier phase difference between the LOS and reflected signals, the probability of detecting multipath is lower when this difference is an integer multiple of π. It has been proposed to use the new civilian signal, L2C to overcome this problem. This thesis presents an analysis of ELP for the L1 and L2C signals, and the combination of both. Their multipath detection performance has been statistically compared using probability of false alarm, probability of multipath detection, Receiver Operator Characteristics (ROC) curves, and the area under the ROC curves. It has been found that the L2C signal individually gives worse performance than L1 but the combination of L1 and L2C gives the best overall performance. ELP is also analyzed for various environmental conditions and receiver settings. It is proposed to average ELP in time to reduce thermal noise effects. However, it is found that at certain fixed and variable “critical Doppler offsets” averaged ELP can have a high magnitude even in the absence of multipath. Differential ELP (DELP) is proposed, which has lower magnitude at these critical Doppler offsets. DELP is then statistically compared with ELP and found not to be a reasonable replacement. Finally, it is proposed to exclude satellites from the navigation solution which are affected by multipath, as detected using ELP. In most of the cases considered, the performance of the ELPbased satellite exclusion has shown to be better or similar to the narrow correlator and high resolution correlator approaches, as long as Dilution of Precision (DOP) is not significantly increased by the exclusion.
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(2010)ThesisThe use of GPS positioning technologies in the agricultural environment has allowed the development of precision guidance systems that have greatly increased farm efficiencies and reduced environmental impacts. With the growing focus on sustainable farming, as well as the increasing demands on food supplies from a growing population, precision agriculture will continue to grow in importance into the future. GPS is the obvious choice to provide the position solution to an agricultural guidance system, however despite generally good GPS conditions in the agricultural environment, outages and obstructions can still occur. This research has focused on a novel method for the integration of the GPS with onboard sensors in order to provide a continuous position solution using an existing GPS data processing engine. The method of integration proposed in this research, called virtuaLites for virtual satellites, would allow the utilisation of the existing GPS engine by transforming the estimated position solution from onboard sensors into range measurements that can then be processed together with any available GPS measurements. This allows the utilisation of any available GPS measurements to bound the growth of the time dependent errors inherent in inertial positioning systems. The bulk of the benefits available from the adoption of precision agriculture practices are only realisable with a centimetre level positioning system. For GPS, this implies a RTK implementation with the fixing of the carrier phase ambiguities to their integer values. VirtuaLites can also be used to increase the precision of the float ambiguities as a preparatory step to fixing the float ambiguities to their integer values. This then decreases the time taken after a loss-of-signal event to reacquire the integer ambiguities and resume precision guidance.
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(2010)ThesisPopulation growth has increased pressures on primary producers, including poultry producers, to competitively produce greater amounts of produce, whilst reducing environmental impact. In addition; the resulting rural encroachment has substantially reduced the buffer distance between primary producers and neighbouring properties, yielding increased odour related complaints. This research project aims to improve understanding of the emission of odorous compounds from poultry facilities by benchmarking analytical methodologies. In particular this thesis focuses on methodologies for speciation of Non-Methane Volatile Organic Compound (NMVOC) and odorant emissions from mechanically ventilated poultry houses in Australia. Laboratory analysis methods (dilution olfactometry) have been established to quantitatively assess odour intensity. However assigning a numerical value to an odour does not provide information relating to its chemical composition or character. An understanding of the chemical composition of the odour is required to better manage the emissions from an operation. While identifying the emitted chemical species provides useful information; the key to understanding the odour is establishing which of the chemical species are odorants. The use of gas-chromatography with simultaneous mass spectral and olfactory detection provides a method of identifying the chemical species present along with their odour potential. Extensive field sampling of broiler and layer facilities was performed to develop an understanding of the emissions of poultry houses. The broiler houses yielded greater chemical diversity and abundance than the layer houses. NMVOCs identified within the emissions included alcohols, aldehydes, ketones, carboxylic acids and terpines. Gains were made in understanding the fate of specific odorants and NMVOCs and the potential impact on emissions. Although beyond the initial scope of the research, interpreting the presence of disulphide species within the emissions was essential to interpreting the overall odour profile. Experimental results reflected a plausible correlation between disulphide presence in samples and thiol presence in the field. Whilst significant laboratory analysis methodological developments were made and an extensive database of results established; the variety of chemical species and abundances between sampling campaigns was a significant result. This variability has identified the need to further investigate litter material of broiler houses as a potential source of nuisance odour emissions.
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(2010)ThesisThe ionosphere is an atmospheric region, which includes a significant number of free thermal electrons and ions located at altitudes of 60km to beyond 1000km above the Earth. The ionosphere can act as the media for long-distance propagation of electromagnetic waves. On the other hand, it also simultaneously disturbs the transmission of these radio signals. Therefore, not only the features of the ionosphere need to be thoroughly studied, but also it is necessary to monitor and predict the ionosphere in near real time through effective ionospheric-detecting instruments and models. Nowadays, it is still a challenging issue to build up accurate and easy-to-use ionospheric models because of the ionospheric variability and lack of very effective instrumentation. The drawbacks of many currently used ionospheric models include: 1) they need to simultaneously combine many different data sources e.g., Global Positioning System (GPS) data, radio occultation (RO) data, data from in situ measurement (i.e., ionosondes, the incoherent scatter radar, the relative ionospheric opacity meter) and the data from the airglow radiances, etc. However, because some of these data sources are difficult to obtain at many target locations at the expected time, it will limit the widespread use of these ionospheric models; 2) based on some special conditions and prior assumptions (or modelling parameters), some of the ionospheric models are accurate. However, when these conditions and parameters change, the model bias may become large and can make the results unsuitable; 3) some kinds of the models only express the ionospheric distribution in a wide area. It may generate a large bias when they are used in a specific location. The major contributions of this study are summarised as follows: (1) Four novel models, which can retrieve electron densities using fewer data sources, are proposed as below: a) A method is proposed to model the electron density bias (with location dependence) generated by the Abel inversion algorithm. When the calculated bias is removed, the accuracy of the retrieved vertical electron density (VED) can be improved. This method only needs a RO event data to generate a more accurate VED profile. b) The electron density is firstly modeled with the parameters of altitude and the zenith angle (with regard to the local centre), and then it is estimated by the tomographic ART (Algebraic Reconstruction Technique) algorithms using the GPS data from a RO event and a ground-based receiver. c) In the ionospheric Shape Function model, the Shape Function is proposed to be altitude and location dependence rather than only altitude dependence (as that in the classic Shape Function model). This Shape Function can be solved by using the GPS data from a RO event and a ground-based receiver. d) The electron density is firstly modeled with the parameters of altitude, the zenith and azimuth angles (with regard to the local centre, and then it is estimated separately by the tomographic ART (Algebraic Reconstruction Technique), the MART (Multiplicative Algebraic Reconstruction Technique) and the Kalman Filter algorithms using the GPS data from a RO event and a ground-based receiver. (2) Two quality control methods for TEC modelling are proposed as follows: a) A method of GPS outlier detection and exclusion in TEC modelling is proposed. Also the impact of outliers on TEC modelling is numerically calculated and analysed. b) In the estimation of the unknown parameters of the TEC models by a Kalman Filter, the impacts from the modelling parameters are numerically analysed. (3) A TEC model, which uses a Kalman Filer to smooth pseudo-ranges and to solve for combined biases in the hardware and the model, is proposed. Based on this model, the TEC temporal and spatial variations, which occurred in Australia in 2006, are analysed.
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(2010)ThesisThe central focus of the GPS modernization program is the addition of new navigation signals. L2C is the first modernized GPS civilian signal to become available over the full constellation by the year 2016. It has an advanced signal structure designed to meet the demands of new and more challenging application environments. Due to its imminent availability and modern code design L2C is likely to be a widely used GPS signal. A GPS L2C receiver must perform an exhaustive search to acquire the signal, due to the unusually long ranging codes used in L2C, consuming substantial resources at the very first stage of digital processing. Dealing with this problem is particularly important for L2C success in the mass market of low-cost mobile devices such as mobile phones and PDAs, constrained by battery power. This dissertation identifies three different approaches for saving processing resources during the L2C acquisition phase. The first approach focuses on the design of the local replica code to accommodate multiple searches in parallel. Several composite codes are proposed to expedite the L2C search and their acquisition performance is evaluated. In the second approach, down-sampling of baseband signals is investigated, to perform correlation at slower rates, saving searches in the code delay dimension whilst reducing the computations per search. A chip-wise correlation strategy is proposed where one correlation per each chip period is sufficient to accomplish a search without compromising detection performance. In the third approach, partial-period correlations are performed to save searches in the Doppler dimension and their outcomes are combined through a semi-coherent differential processing technique. The detection performance of this approach is shown to be competitive with the full-period correlation. The L2C signal is also the first fully accessible signal to join the legacy L1 C/A signal to serve dual frequency civil users. In this context, two different investigations are carried out in this thesis. First, it is identified that while longer L2C codes might appear a straightforward decision to combat the cross-correlation interference in a dual frequency GPS L1/L2C receiver, in fact L1 C/A is more robust in the Assisted-GPS, warm start and reacquisition scenarios. Secondly, a scheme for improving sensitivity and measurement accuracy of the L1 carrier tracking loop by providing aiding from the L2C PLL is evaluated. A margin of at least 3 dB against the effects of radio frequency interference is shown to be achieved by the aided-L1 tracking loop, while such benefits might previously have been obtained though inertial aiding.
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(2010)ThesisThe research presented in this thesis is concerned with the time-dependent behaviour of reinforced concrete and the mechanisms of tension stiffening. The research program comprises both experimental investigation and numerical modeling. The aims are to provide a comprehensive understanding about tension stiffening under short-term and long-term loading.Of particular interests are the effects of concrete creep and shrinkage on the change of tension stiffening with time. The experimental program involved testing axially loaded reinforced concrete prisms and simply-supported reinforced concrete beams and slabs under short-term and long-term loadings. The experimental results have demonstrated that tension stiffening is greatly influenced by the drying shrinkage of concrete, the extent of cracking and the deterioration with time of the bond between the reinforcement and the concrete. A two-dimensional continuum-based finite element model has been developed. The model incorporates instantaneous and time-dependent constitutive laws for concrete, steel and importantly the bond interface between them. A shrinkage-related bond model has been proposed to accurately model the loss of tension stiffening under long-term loading. The finite element model has been used to simulate the response of the test specimens and the numerical results are in close agreement with the experimental results. A parametric study has also been undertaken using the finite element model; the effects of different parameters (concrete cover, reinforcing ratio, etc.) on time-dependent tension stiffening have been examined. The significance of each parameter has been discussed.