Infrastructure Engineering - Theses
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ItemTrip quality in peer-to-peer shared ride systems( 2007-01)In a peer-to-peer shared ride system, transportation clients with traffic demand negotiate with transportation hosts offering shared ride services for ad-hoc ridesharing in a continuously changing environment, using wireless geosensor networks. Due to the distinctive characteristic of this system—a complex and non-deterministic transportation network, and a local peer-to-peer communication strategy—clients will always have limited transportation knowledge, both from a spatial and a temporal perspective. Clients hear only from nearby hosts, and they do not know the future availability of current or new hosts. Clients can plan optimal trips prior to departure according to their current knowledge, but it is unlikely that these trips will be final optimal trip due to continuously changing traffic conditions. Therefore, it is necessary to evaluate the trip quality in this dynamic environment in order to assess different communication and wayfinding strategies. (For complete abstract open document)
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ItemAgent behavior in peer-to-peer shared ride systems( 2007-01)Shared ride systems match the travel demand of transport a client with the supply of vehicles, or hosts, so that the client find rides to their destinations. A peer-to-peer shared ride system allows a client to find rides in an ad-hoc manner, by negotiating directly with nearby hosts via radio-based communication. Such a peer-to-peer shared ride system has to deal with various types of hosts, such as private cars, taxicabs and mass transit vehicles. Agents, i.e. a client and hosts, have diverse behaviors in such systems. Their different behaviors affect the negotiation process, and consequently the travel choices. Preliminary research (Winter et al. 2005) has investigated peer-to-peer shared ride systems with homogeneous hosts and immobile client. This thesis extends their work to multiple types of agents. It focuses on what are typical agent behaviors in peer-to-peer shared ride systems, and how these behaviors affect negotiation processes in a dynamic transport environment. (For complete abstract open document)
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ItemAn SDI model to include the marine environment( 2006-07)Currently Spatial Data Infrastructure (SDI) initiatives are mainly focused on the terrestrial environment and have not yet expanded to fully accommodate marine and coastal spatial information. This causes many stakeholders within the marine and coastal environments difficulty in obtaining spatial data or information about these areas. Therefore the aim of this research is to develop an extended seamless SDI model that can apply to coastal and marine spatial data as well as terrestrial data. This thesis explains the need for improved management of the marine and coastal environments, in terms of sustainable development and the importance of spatial information to underpin administration of the various rights, restrictions and responsibilities in these areas. It also discusses the common understanding and views of the nature, concept and components of SDI. Different views about the development and implementation of SDI are explored and the Australian Spatial Data Infrastructure (ASDI) is used as a real-life example of an SDI. (For complete abstract open document)
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ItemDecision-making under spatial uncertainty( 2005)Errors are inherent to all spatial datasets and give rise to a level of uncertainty in the final product of a geographic information system (GIS). There is growing recognition that the uncertainty associated with spatial information should be represented to users in a comprehensive and unambiguous way. However, the effects on decision-making of such representations have not been thoroughly investigated. Studies from the psychological literature indicate decision-making biases when information is uncertain. This study explores the effects of representing spatial uncertainty, through an examination of how decision-making may be affected by the introduction of thematic uncertainty and an investigation of the effects of different representations of positional uncertainty on decision-making. Two case studies are presented. The first of these considers the effects on decision-making of including thematic uncertainty information within the context of an airport siting decision task. An extremely significant tendency to select a zone for which the thematic classification is known to be of high certainty was observed. The reluctance to select a zone for which the thematic classification is of low certainty was strong enough to sometimes lead to decision-making that can only be described as irrational. The second case study investigates how decision-making may be affected by different representations of positional uncertainty within the context of maritime navigation. The same uncertainty information was presented to participants using four different display methods. Significant differences in their decisions were observed. Strong preferences for certain display methods were also exhibited, with some representations being ranked significantly higher than others. The findings from these preliminary studies demonstrate that the inclusion of uncertainty information does influence decision-making but does not necessarily lead to better decisions. A bias against information of low certainty was observed, sometimes leading to the making of irrational decisions. In addition, the form of uncertainty representation itself may affect decision-making. Further research into the effects on decision-making of representing spatial uncertainty is needed before it can be assumed that the inclusion of such information will lead to more informed decisions being made.
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ItemDuctility of one-way slabs constructed with class L mesh, Grade 500 steel, under support settlement( 2005)This study investigates the impact of new class L Grade 500 Australian steel on the behaviour of suspended reinforced concrete slabs. An experimental program consisting of two one-way full-scale slabs constructed with class L steel was carried out. The key focus of the test program was to examine the response of slabs under imposed support settlements, which could occur for various reasons in the life of a structure. The experimental results were compared with the numerical results obtained by using the computer software prepared by Dr. Rebecca Gravina at The University of Adelaide, SA. Two continuous one-way slabs, with spans more than 4 m and 5 m respectively, constructed with class L steel were tested under imposed support settlement. A typical value of support settlement was used to raise the intermediate support of one test slab and to lower the intermediate support of the other. The results recorded using various techniques were used to establish the load-deflection curves, moment-rotation curves, degree of moment redistribution, failure loads and crack patterns at different load stages during the tests. A comparison of the experimental results with the numerical study carried out by Dr. Rebecca Gravina using software developed in her PhD studies showed a good agreement between the two results. This study showed that the test slabs were able to resist a load higher than the design load, even when subjected to support settlements of a magnitude expected in practice. Also the test slabs developed significant cracking in the spans as well as over the intermediate support regions before failure. The load deflection curves showed little sign of ductility. Moreover, the failure in each case was in a catastrophic manner by fracture of steel in the negative moment region, with no sign of compressive concrete crushing. This study has provided a detailed experimental investigation about the behaviour of class L steel under support settlement effects. However, it is limited to one-way slabs and has used reinforcement provided one steel manufacturer. It can be further extended to two-way slabs and also to class N steel for comparison with class L behaviour.
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ItemEffective diffusion coefficients for charged porous materials based on micro-scale analyses( 2009)Estimation of effective diffusion coefficients is essential to be able to describe the diffusive transport of solutes in porous media. It has been shown in theory that in the case of uncharged porous materials the effective diffusion coefficient of solutes is a function of the pore morphology of the material and can be described by their tortuosity (tensor). To estimate the apparent diffusion coefficients, the values of tortuosity and porosity should be known first. In contrast with calculation of porosity, which can be easily obtained, estimation of tortuosity is intricate, particularly with increasing micro-geometry complexity in porous media. Moreover, many engineering materials (e.g, clays and shales) are characterized by electrical surface charges on particles of the porous material which can strongly affect the diffusive transport properties of ions. For these materials, estimation of effective diffusion coefficients have been mostly based on phenomenological equations with no link to underlying microscale properties of these charged materials although a few recent studies have used alternative methods to obtain the diffusion parameters. In the first part of this thesis a numerical method based on a recently proposed up-scaled Poisson-Nernst-Planck type of equation (PNP) and its microscale counterpart is employed to estimate the tortuosity and thus the effective and apparent diffusion coefficients in thin charged membranes. Beside this, a new mathematical approach for estimation of tortuosity is applied and validated. This mathematical approach is also derived while upscaling of micro-scale Poisson-Nernst-Planck system of equations using the volume averaging method. A variety of different pore 2D and 3D micro-geometries together with different electrochemical conditions are studied here. To validate the new approaches, the relation between porosity and tortuosity has been obtained using a multi-scale approach and compared with published results. These include comparison with the results from a recently developed numerical method that is based on macro and micro-scale PNP equations. Results confirm that the tortuosity value is the same for porous media with electrically uncharged and charged particles but only when using a consistent set of PNP equations. The effects of charged particles are captured by the ratio of average concentration to effective intrinsic concentration in the macroscopic PNP equations. Using this ratio allows to consistently take into account electro-chemical interactions of ions and charges on particles and so excludes any ambiguity generally encountered in phenomenological equations. Steady-state diffusion studies dominate this thesis; however, understanding of transient ion transport in porous media is also important. The last section of this thesis briefly introduces transient diffusion through bentonite. To do so, the micro Nernst-Planck equation with electro-neutrality condition (NPE) is solved for a porous medium which consists of compacted bentonite. This system has been studied before in another research using an experimental approach and the results are available for both transient and steady-state phases. Three different conditions are assumed for NPE governing equations and then the numerical results from these three conditions are compared to the experimental values and analytical phenomenological solution. The tortuosity is treated as a fitting parameter and the effective diffusion coefficient can be calculated based on these tortuosity values. The results show that including a sorption term in the NPE equations can render similar results as the experimental values in transient and steady state phases. Also, as a fitting parameter, the tortuosity values were found varying with background concentration. This highlights the need to monitor multiple diffusing ion fluxes and membrane potential to fully characterize electro-diffusive transport from fundamental principles (which have been investigated in first part of this thesis) rather than phenomenological equations for predictive studies. This research has lead to two different journal articles submissions, one already accepted in Computers and Geotechnics (October 22, 2009, 5-yrs Impact Factor 0.884) and the other one still under review.
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ItemConjunctive management of groundwater and surface water resources in the Upper Ovens River Valley( 2009)The Upper Ovens River catchment is located in the Victorian high plains of Australia. With an absence of major storages or weirs, the flow regime of the Upper Ovens River is close to its natural magnitude and frequency. Water extraction from rivers has the potential to negatively impact on environmental flow requirements and management of extraction is required to maintain flows to the river, especially over the low flow summer periods. The Upper Ovens River has been shown to have a high connectivity between groundwater and surface water, and for effective protection of stream flow, it is proposed that groundwater and surface water are managed conjunctively by a government legislated Water Management Plan. Environmental stream flow objectives have been identified, but no method exists to link these to groundwater objectives. Without this link, water resource managers cannot develop management methods or plans for management of groundwater to achieve surface flow objectives. Existing data commonly available to water resource managers was analysed to develop a method to link stream flow objectives to groundwater management objectives, and investigate the groundwater-surface water relationship and water cycle in the Upper Ovens catchment. A water balance for a well defined sub-catchment was developed for the period between 1975 and 2005 to investigate the water cycle and magnitude of fluxes between groundwater in the unconsolidated sediments of the valleys and surface water. Darcy’s law and statistical regression analysis of commonly available historic data were used to develop the understanding of the groundwater-river level relationship and produce a method for relating environmental river flow targets to groundwater levels. A set of conjunctive management principles for resource managers was produced based upon the sound scientific understanding of groundwater-surface water interactions. The mean water balance shows a clear seasonal pattern for movement of water between surface water and groundwater. Groundwater levels have remained steady, with average annual groundwater recharge from rainfall and the river of 9,773 ML nearly equal to average annual discharge of 9,584 ML from the aquifer as baseflow or evaporation in the dry season. Generally extraction of groundwater and surface water (3,200 ML/yr) and fluxes between groundwater and the river (2,626 ML/yr), are only minor components of the water balance (560,000 ML/yr) and do not affect the flow patterns in the Ovens River. However, in years with very low flows over the Summer/Autumn period, extraction from the river can significantly reduce flow in the river. Management of river flow at this time is the focus for water resource managers. Field measurements and regression relationships showed a rapid rate of flux between groundwater and the river with the time lag (for rises in river level to subsequent rises in groundwater levels) increasing with distance of the aquifer from the river to be 14-20 days at the maximum measured distance of 750 metres from the river. With the narrow width of the unconsolidated sediment aquifer (less than 3000 metres) extraction of groundwater from these aquifers is expected to impact on stream flows within the summer period (90 days). Regression analysis produced equations for relating Ovens River levels to groundwater levels with a high correlation. These equations can relate stream flow objectives to corresponding groundwater management that can be used by resource managers with a high level of confidence. Groundwater and surface water, in the form of river flows, are intrinsically linked and to protect flows in the Ovens River during times of low flow, groundwater has to be managed in line with surface water. Four principles have been identified for conjunctive management in the Upper Ovens, and resource managers should set management rules based on the following principles: 1) Groundwater and surface water are hydraulically connected, manage as one; 2) Restrict groundwater extraction in line with surface water restrictions; 3) Manage groundwater to minimum groundwater levels; and 4)Manage groundwater in the unconsolidated sediments as one aquifer.
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ItemThe intelligent placement of vegetation objects in 3D worlds( 2009)In complex environments, increasing demand for exploring natural resources by both decision makers and the public is driving the search for sustainable planning initiatives. Among these is the use of virtual environments to support effective communication and informed decision-making. Central to the use of virtual environments is their development at low cost and with high realism. This paper explores intelligent approaches to objects placement, orientation and scaling in virtual environments such that the process is both accurate and cost-effective. The work involves: (1) determining of the key rules to be applied for the classification of vegetation objects and the ways to build an object library according to ecological classes; (2) exploring rules for the placement of vegetation objects based on vegetation behaviours and the growth potential value collected for the research area; (3) developing GIS algorithms for implementation of these rules; and (4) integrating of the GIS algorithms into the existing SIEVE Direct software in such a way that the rules find expression in the virtual environment. This project is an extension of an integrated research project SIEVE (Spatial Information Exploration and Visualization Environment) that looks at converting 2D GIS data into 3D models which are used for visualization. The aims of my contribution to this research are to develop rules for the classification and intelligent placement of objects, to build a normative object database for rural objects and to output these as 2D billboards or 3D models using the developed intelligent placement algorithms. Based on Visual Basic Language and ArcObjects tools (ESRI ArcGIS and Game Engine), the outcomes of the intelligent placement process for vegetation objects are shown in the SIEVE environment with 2D images and 3D models. These GIS algorithms were tested in the integrated research project. According to the case study in Victoria, rule-based intelligent placement is based on the idea that certain decision-making processes can be codified into rules which, if followed automatically, would yield results similar to those which would occur in the natural environment. Final product produces Virtual Reality (VR) scenes similar to the natural landscapes. Considering the 2D images and 3D models represented in the SIEVE scenario and the rules (for natural and plantation vegetation) developed in conjunction with scientists in the Victorian Department of Primary Industries (DPI) and other agencies, outcomes will contribute to the development of policies for better land and resource management and link to wide ranging vegetation assessment projects.
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ItemSeismic performance of concrete beam-slab-column systems constructed with a re-usable sheet metal formwork system( 2007)This report describes an investigation of seismic performance of a ribbed slab system constructed with an innovative re-usable sheet metal formwork system. Experimental results from quasi-static cyclic lateral load tests on half-scale reinforced concrete interior beam-slab-column subassemblages are presented. The test specimen was detailed according to the Australian code (AS 3600) without any special provision for seismicity. This specimen was tested up to a drift ratio of 4.0 %. Some reinforcement detailing problems were identified from the first test. The damaged specimen was then rectified using Carbon Fibre Reinforced Polymer (CFRPs), considering detailing deficiencies identified in the first test. The repaired test specimen was tested under a lateral cyclic load as per the original test arrangement up to a drift level of 4%. The performance of the repaired specimen showed significant improvement with respect to the level of damage and strength degradation. The results of the rectified specimen indicate that the use of CFRPs may offer a viable retrofit/repair strategy in the case of damaged structures, where this damage may be significant. Two finite element analysis models were created and results of the first test were used to calibrate the FE model. The second FE model was used to obtain detail information about stress and strain behaviour of various components of the beam-column subassemblage and to check the overall performance before carrying out expensive lab tests. It was concluded that finite element modelling predictions were reliable and could be used to obtain more information compared to conventional type laboratory tests. Time-history analyses show that the revised detailing is suitable to withstand very large earthquakes without significant structural damage.
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ItemActive transport journey planner methodology( 2009)This research aims to define and develop a methodology to assist an individual traveller to select healthier and more sustainable transport routes and modes among admissible transport options and highlight the trade-offs among multiple objectives in terms of health, economic, social and environmental benefits. It aims to assist an individual traveller with multi-objectives to make more informed decisions in route and mode planning. The objectives in the case study were identified as personal energy expenditure, travel time, travel cost, CO2 emissions and energy resource consumption concerning sustainability. This research presents procedures for estimating a range of costs and benefits for journeys; procedures for determining the optimal route for an individual’s trip in an urban area based on cost and benefit estimates and preference weights for specific objectives; procedures for undertaking sensitivity analysis for the optimal route; and uses of the cost and benefit estimation and optimal route generation procedures to conduct a case study for a realistic journey in Melbourne. An active transport journey planner model was developed in MS Excel to allow users to set constraints for most objectives and give their corresponding weightings, respectively. The recommended transport solution (the least total disutility one) and ranking of other options along with their detailed objective-related information are derived. A case study shows that the methodology developed could be applied in selecting more informed transport solutions based on the user’s multi-objective preferences. In addition, transport options incorporating more cycling and walking have the higher probability to deliver healthier and more sustainable solution to users if social, environmental concerns were considered beyond economic issues. Meanwhile, in sensitivity analysis, the tornado diagrams and spiderplots diagrams are used for demonstrating how sensitive each transport option’s disutility is to the weightings of objectives.