Infrastructure Engineering - Theses
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ItemA one-dimensional Boussinesq-type momentum model for steady rapidly varied open channel flows( 2004-11)The depth-averaged Saint-Venant equations, which are used for most computational flow models, are adequate in simulating open channel flows with insignificant curvatures of streamlines. However, these equations are insufficient when applied to flow problems where the effects of non-hydrostatic pressure distribution are predominant. This study provides a comprehensive examination of the feasibility of a simple one-dimensional Boussinesq-type model equation for such types of flow problems. This equation, which allows for curvature of the free surface and a non-hydrostatic pressure distribution, is derived using the momentum principle together with the assumption of a constant centrifugal term at a vertical section. Besides, two Boussinesq-type model equations that incorporate different degrees of corrections for the effects of the curvature of the streamline are investigated in this work. One model, the weakly curved flow equation model, is the simplified version of the flow model based on a constant centrifugal term for flow situations that involve weak streamline curvature and slope, and the other, the Boussinesq-type momentum equation linear model is developed based on the assumption of a linear variation of centrifugal term with depth.
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ItemMaking sustainable develoment ideas operational( 2004)The purpose of the thesis is to develop a General Technique (GT) for use by investigators as a template to help devise investigation programs applying sustainable development ideas (SDIs) to presenting-issues, in order to create ideas for sustainable development actions (SDAs). SDIs are the ‘ideals’, of behaviour for relations amongst people (people-matters) and between people and the environment of the planet (planet-matters) having ancient origins yet being constantly reinterpreted. SDAs are actions that synergistically deliver SDIs in both people-matters and planet-matters concomitantly. The GT was devised in a learning cycle involving theory development and practical experience. The theory of the GT uses a systems-thinking approach to set out the blocks of information necessary to apply SDIs to a presenting issue. The mental model used in the GT is based on the concepts that people are dependent on the planet and that every individual and their actions count. The GT has a Preliminary Step and four Tasks. The Preliminary Step establishes the relationships between the roles of stakeholders and the presenting-issue using a ‘4-group-stakeholder theory’;; group 1 are agents/individuals, groups 2 and 3 are organisations that operate in planet-matters and people-matters respectively, and group 4 are the general public/future generations. Everybody has group 1 and 4 roles and employed people play roles 2 and 3. Task 1 investigates the actions and agents that are fundamental in the presenting issue.Task 2 investigates the agents’; motivations to take up opportunities in both people and planet-matters. Motivations are based on the agents’; desire to satisfy the fundamental human needs (FHNs) of their family. Task 3 investigates: (a) the opportunities in people-matters and planet-matters, using a theory that posits that critical resources and critical arrangements are required for the delivery of FHNs in the very long-term. (b) The involvement stakeholders’; groups have in these opportunities.Task 4 reviews: (a) the success of groups 1 and 4 stakeholders in getting their FHNs met in the long-term and how successful stakeholder groups 3 and 4 are in helping them and why. (b) The maintenance of critical resources compared to the level needed to maintain all life forms and life system on the planet. (For complete abstract open document)
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ItemA framework for the evaluation of land administration systems( 2004-02)There are currently no accepted frameworks or methodologies to compare and evaluate national land administration systems. Comparisons, however, are an important source for learning and for identifying strengths and weaknesses. Part of the difficulty for adopting a common comparison framework for land administration systems is that they are in constant reform and, more importantly, they have strong social and cultural links and implications. Land administration systems reflect the particular and different perceptions that societies have of their land. (For complete abstract open document)
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ItemIntegrated position and attitude determination for augmented reality systems( 2004-10)One of the most challenging tasks for augmented reality systems is that of position and attitude determination in outdoor unprepared environments. Augmented reality, a technology that overlays digital information with views of the real world, requires accurate and precise position and attitude determination to operate effectively. For small (often indoor) areas, careful preparation of the environment can allow for augmented reality systems to work successfully. In large outdoor environments, however, such preparation is often impractical, time-consuming and costly. This thesis aims to investigate the development of a position and attitude determination component for augmented reality systems capable of operation in outdoor unprepared environments. The hypothesis tested in this investigation is that the integration of Global Positioning System (GPS), Dead Reckoning (DR) and map matching techniques enables the continuous and accurate real-time visual alignment of three-dimensional data with objects in the perspective view of a user operating in outdoor unprepared environments.
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ItemModelling the flow regime of arid zone, floodplain rivers( 2004-08)The requirements of ecological studies and water resource management plans are driving demand for hydrological models of the rivers of the arid zone. Knowledge of the hydrology of Australia’s arid zone is poor, yet is critical in understanding the ecology of the region. The research presented in this thesis seeks to address some shortcomings in our understanding of the hydrology of the Australian arid zone. In particular, the research examines the requirements for modelling the flow regime of arid zone rivers, concentrating on the rivers of the Lake Eyre Basin (LEB). The LEB has exceptionally low annual runoff of 3.5 mm, its major rivers develop over extremely low gradients and are characterised by very wide floodplains and complex anastomosing flow paths in their mid to lower reaches. This research was driven by both a practical and theoretical impetus. Practically, hydrological data were required at the water body scale for a large number of sites across three river systems of the LEB, for use in a study, known as ARIDFLO, of the ecological responses to hydrological conditions. Because of the remoteness of these sites and the paucity of gauging stations on these rivers, modelling of the rivers was the only method for delivering the required discharge data. Theoretically, the challenge was set for creating hydrological models for some extraordinarily complex river systems, in terms of their size, catchment characteristics and flow regime variability. (For complete abstract open document)
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ItemPlasterboard as a bracing material: from quality control to wall performance( 2004)The recently revised Residential Timber-Framed Construction Standard (ASI684-1999) explicitly specifies the bracing contribution of nominally fixed plasterboard, which has been traditionally treated as a non-structural component by designers. The inclusion of the bracing strength of plasterboard in the standard has been done without associated changes to the control of structural properties of plasterboard. In other words, plasterboard manufacturers could modify the properties of plasterboard without any requirement of ensuring the bracing performance of the plasterboard. This study has identified the lack of understanding of the relationship between the material properties of plasterboard and its bracing performance and has added to the current state of knowledge. With this understanding, a new test method described as fastener bearing test has been proposed, developed and verified such that plasterboard manufacturers could use this test to quantify the bracing capacity of plasterboard as part of the manufacturing process. The fastener bearing test was validated through an extensive experimental program, which comprised density tests, shear connection tests and full-scale isolated wall racking tests, and has proven to be reliable in controlling the bracing quality of plasterboard. The proposed test is simple and could be applied without severe cost or time penalty to plasterboard manufacturers. The knowledge gained from the experimental analyses has been incorporated into two analytical models to predict the load-displacement response of plasterboard clad walls in Australian residential structures under monotonic racking load. The first analytical model was' developed using finite element (FE) techniques where various types of elements were employed. In addition to the FE model, a new closed-form mathematical model, described as 'Modularised' Closed-Form Mathematical (MCFM) model, has also been developed and validated. This MCFM model is the first closed-form mathematical model which has the capability of assigning different load-slip characteristics for sheathing-to-framing connections (shear connections). The effects of the fastener locations have proven to be particularly important for walls clad with plasterboard. In addition, the model is also capable of generating the shape of stud deformation based on the load-slip characteristics of shear connections and stud properties. This analytical model has proven to be flexible in accommodating various nailing patterns and different framing member dimensions. The findings of this study have significantly contributed to the understanding of the bracing performance of plasterboard, the behaviour of plasterboard clad walls and to some extent, the behaviour of residential light-framed structures when subjected to lateral wind loading. This study has produced reliable and effective analytical models, particularly the MFCM model which is suitable for developing simple and cost effective computer programs for everyday design. Significant interests in the findings of this study have been expressed by Boral Australian Gypsum and CSR Building Materials, the two largest plasterboard manufacturers in Australia.
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ItemEjector cooling with reference to combined ejector-vapour compression system( 2004)A study about an ejector refrigeration system with focus on the combined ejector-vapour compression system has been carried out. The study was divided into three stages; one-dimensional analysis, CFD modelling and experiment. In the one-dimensional analysis, a selection process for the working fluid in the combined system was carried out. This involved screening of a refrigerant database to find refrigerants that satisfied (to a certain extent) a number of criteria identified for an ideal working fluid in the combined system. A one-dimensional ejector refrigeration model was developed to examine several potential refrigerants selected. This model was based on the constant-pressure-mixing theory that analysed the flow in the ejector as an isentropic flow with a normal shock taking place in the constant area duct of the ejector. R 141b and R245fa were among those identified as the most beneficial working fluids in the combined system through comprehensive single and dual refrigerant analyses. Further analyses on the effects of intercooler temperature on the overall system performance and refrigerant responses towards intercooler temperature variation were presented. It was discovered that the intercooler temperature had a vital effect on the ejector performance. The results of intercooler temperature effects in terms of COPth, COPpe and COPme were indicating that for a condenser temperature selected as low as 40°C the intercooler temperature (evaporator temperature for the ejector cycle) was most suitably selected at 32°C. It was also found that different refrigerants responded differently towards intercooler temperature variation and water as one of the refrigerants considered had a good potential for use in the ejector cycle at very high intercooler temperatures. CFD was used in the second stage of the study to model several ejectors and compare the results obtained with published data about ejectors using R141b as the working fluid. This first step was for validating the modelling approach and prediction accuracy of the CFD analysis. The outcome was encouraging because the CPD predicted results had a better coefficient of correlation to the experimental data than that of the one-dimensional analysis. The flow field of the ejector was then studied to see the characteristics of the flow when the generating temperature was increased from 80°C to IS0°C in the CFD simulations of a theoretically designed RI4Ib ejector. Three distinct flow fields related to the operating conditions were identified and the flow field Mach number contour plot clearly displayed the differing characteristics of the three flow scenarios. Relating those flow scenarios with the ejector entrainment ratio, it was concluded that the ejector would have the best performance when operating at an over expansion state with the secondary flow choked but no presence of normal shock in the ejector. The effects of ejector geometry on performance were given a close look when the constant area diameter and nozzle exit distance to the constant area tube entrance were varied in the subsequent CFD simulations. It appears the scenarios between the flow field and the operating conditions above did apply to enlargement of the constant area diameter when best performance was being sought. A less significant effect was observed for the nozzle exit distance. These findings backed with valid CFD results were useful for improved ejector designs. An ejector test rig was then built to test an R141b ejector in the last stage of the study. The process took several major steps from design, construction, leak testing and establishing control strategy before experimental data gathering could be undertaken. The measurement of the primary and secondary flow rates was given a great emphasis by utilising a superior mass flow meter that had an accuracy of 0.1 % of the measured flow. This was achieved through using a specially designed flow switching loop that enabled measurements of two different flow rates with one flow meter without imposing too much disturbance to the measurements. The ejector was subjected to the basic tests and superheat tests. In the basic tests the conditions at the generator, condenser and evaporator were varied individually and the ejector entrainment ratio was recorded and examined. The superheat tests were carried out for up to 20°C superheat at the ejector inlets to see how this would affect ejector performance. The results from the basic tests showed a number of familiar ejector operating characteristics but the main finding had been the way the entrainment ratio curve peaked at around 95°C generating temperature at the combined system evaporating temperature of 32°C. At lower evaporating temperatures, the lower entrainment ratio curves peaked at correspondingly higher generating temperatures.
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ItemStochastic joint probability modelling of estuarine flood levels( 2004)The determination of the annual exceedence probability (AEP) of extreme water levels, such as the 1% AEP flood level, in complex estuarine systems is an important and yet highly challenging issue. Water level AEP is required for land and water resources planning, emergency management and flood insurance underwriting. Extreme water levels in estuaries are caused by the combined effects of environmental forcings (river floods, winds and coastal ocean levels (COLs)), estuarine hydrodynamics, floodplain topography and catchment conditions. A comprehensive flood study should therefore entail a detailed hydrological, hydraulic and terrain modelling of the entire system. Unfortunately, there is currently no standard procedure for undertaking such a study. The question asked in this thesis is: "Is it possible to estimate, in a scientifically rigorous but computationally efficient way, the AEP of extreme water levels in large and complex estuarine systems such that the spatial and temporal forcing characteristics ranging from catchment to synoptic scales are preserved?" This question is addressed by developing a generic modelling method for application to any estuaries, and testing it on the Gippsland Lakes in southeast Australia - a coastal lagoon system having water surface area of almost 400 km2 and contributing catchment area of over 20,000 km2. The new method is a stratified Monte-Carlo stochastic-deterministic hydro-climatic modelling-based joint probability (MBJP) method. Conceptually, two thousand years of stochastic event-based concurrent hourly forcing sequences (river flows, winds and COLs) that preserve the space-time cross-correlations are generated using a sequence of hydro-climatic models developed in this thesis. Monte-Carlo (MC) simulation of event-based water levels around the estuarine system is then carried out using a calibrated hydrodynamic model (HDM) driven by the generated stochastic forcing sequences. (From Abstract)