Civil Engineering - Theses

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    Effect of land surface heterogeneity on satellite near-surface soil moisture observations
    Panciera, Rocco. (University of Melbourne, 2009)
    This thesis develops a technique to reduce the error in near-surface soil moisture estimates from spacebome passive microwave sensors, by accounting for the heterogeneity of land surface conditions within the sensor field of view. Using experimental data collected in the course of this research, it is demonstrated that this technique will significantly reduce the error in satellite near-surface soil moisture retrieval. The technique has been developed specifically for the first dedicated passive microwave soil moisture satellite, the European Soil Moisture and Ocean Salinity Mission (SMOS), which will use L-band (1.4GHz) measurements to map nearsurface soil moisture globally at a near-daily time scale. The main steps taken to develop these techniques are the first evaluation of the core radiative transfer model of the SMOS soil moisture retrieval algorithm for the Australian conditions using airborne data, and an analysis of the land surface controls on near-surface soil moisture distribution at the satellite footprint scale. These initial steps provided the tools in order to test the accuracy of the soil moisture retrieval approach proposed for SMOS at the satellite footprint scale in the presence of spatial variability of the land surface, and to develop a new retrieval approach for SMOS which overcomes the shortfalls identified in the SMOS proposed approach.
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    Addressing uncertainties associated with water accounting
    Lowe, Lisa Diane. (University of Melbourne, 2009)
    Water accounts provide information to a range of stakeholders who make decisions related to water. There are significant challenges in quantifying all of the information elements included in water accounts. Some information elements are measured while others are estimated. There is uncertainty associated with the information presented in water accounts, either due to measurement uncertainty or the assumptions made during the estimation process. The presence of uncertainties in water accounts poses two problems. Firstly, the decisions made based on information presented in the accounts may change if the associated uncertainties were disclosed. Secondly, due to the uncertainties associated with each element, the accounts rarely balance. At present the uncertainty in water accounts is not well understood and it is not systematically captured and reported in the accounts. This thesis identifies and quantifies the major sources of uncertainty in water accounts. Established techniques to quantify the uncertainties are only available for a few of the elements. A number of new techniques are developed to quantify the uncertainty associated with elements that include unmetered water use, net evaporation from storages, reservoir volumes and impacts of farm dams. A general framework to quantify uncertainties is developed and applied to a case study, the Werribee River basin (Victoria, Australia). The largest uncertainties in this catchment are associated with estimating rainfall runoff and surface water -groundwater interactions. A new method to constrain the uncertainty associated with each component of the water accounts and to create a balanced set of accounts, based on numerical data reconciliation, is presented. If the uncertainty surrounding each element is known, it is possible to improve the estimates and reduce the uncertainties by removing combinations of inflows and outflows that do not create a balanced set of accounts. Existing analytical techniques to perform the required calculations for data reconciliation are not suitable in water accounting because they assume that all uncertainties can be described using a Gaussian distribution. In order to incorporate other types of probability distributions, a numerical technique is developed. Overall, this thesis presents three new contributions: an identification of information elements which are useful to decision makers; a quantification of uncertainties associated with the elements reported in water accounts and methods are presented to quantify these uncertainties; a new numerical method, data reconciliation, to minimise the uncertainties by considering the joint probability of all inflows and outflows that create a balanced set of accounts.
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    A hybrid microsimulation model of freight transport demand
    Donnelly, Richard Ren�. (University of Melbourne, 2009)
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    Intersectoral water allocation : valuing water and the case for water property rights
    Glennie, Paul Rog�r. (University of Melbourne, 2006)
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    Intersectoral water allocation : valuing water and the case for water property rights
    Glennie, Paul Rog�r. (University of Melbourne, 2006)
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    The structure and strength of Victorian brown coals
    Rosengren, K. J. (University of Melbourne, 1961)
    A soil mechanics investigation into the structure and strength of Victorian brown coals has been performed and the results of consolidation and triaxial tests explained in terms of a proposed model of coal structure. Brown coal possesses a porous skeleton with aggregates of planar aromatic molecules cross-linked by aliphatic chain structures. The aggregates are effectively in contact with direct chemical linking at the points of contact. However, the bonding within the aggregates is much stronger than that between aggregates and the response of brown coal to stress is dominated by the inter-aggregate contact forces. Brown coal follows an effective stress law and a Hvorslev type law, with Ce/Je approximately 0.25 and �e approximately 35�, is applicable. A frictional type shear strength law is suggested and, good agreement is found between predicted and measured tensile strengths. Consolidation behaviour closely resembles that of a clay and the distribution of moisture contents in brown coal seams is shown to be a consolidation phenomenon. Other features in common with clays are the correlation of dimensionless parameters and the existence of a critical voids ratio line.
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    Further understanding ground source heat pump system design using finite element methods and machine learning techniques
    Makasis, Nikolas ( 2018)
    Ground-source heat pump (GSHP) systems can efficiently provide renewable energy for space heating and cooling. Even though these systems have shown great potential, contributing towards the continuously increasing energy demand and reducing greenhouse gas (GHG) emissions, our understanding of how they can be best utilised and designed can still be improved. This research adopts detailed numerical modelling and statistical approaches to provide further insights on these systems and contribute towards their worldwide adoption, focusing on three main areas. Firstly, due to the nature of their installation, there can exist disparities between the designed and installed systems. One such design-installation disparity, variable geothermal pipe separation, is addressed, aiming to reduce the gap between theory and practice. Secondly, due to the relatively recent emergence of energy geo-structures, such as energy piles or retaining walls, there currently exists little information on their utilisation/design. Therefore, an in-depth numerical analysis on energy geo-structure thermal performance is provided, focusing on the less well-researched energy retaining walls and providing suggestions on important factors such as the thermal demand, structure geometry and pipe configuration. Finally, two statistical approaches are presented that complement numerical modelling (often adopted for energy geo-structure analysis) and significantly reduce the computational time/resources associated, making numerical analysis and design of GSHP systems more accessible to engineering practice.
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    Design optimisation for off-site manufacture and assembly of MEP systems
    Samarasinghe, Tharindu Tharanga ( 2018)
    Modularisation and Standardisation for prefabrication of mechanical, electrical and plumbing (MEP) systems have become more prevalent during the last decade with the growth of the prefabricated construction industry. Speedy construction, minimum onsite labour, improved quality and waste reduction are the key benefits that make prefabrication superior to conventional construction. However, in MEP, modularisation and standardisation are currently applied only to smaller systems, where integrated packaged units are used in heating, ventilation and air conditioning (HVAC) and other building services installations. Modular prefabrication is rarely practiced when services are located within the building due to limitations during installation and difficulty in coordination. The term ‘optimum modularity’ is not accurately used in the field, and identification of modules is solely based on individual judgement than a structured method. The absence of a structured method for modularisation in MEP has made the identification of modules for prefabrication a time-consuming process, that often fails to achieve the optimum module division with minimum installation cost. In most cases, this has resulted in modular prefabrication of MEP being the same cost as conventional construction or even higher. This is one of the main reasons that impedes the use of modular prefabrication in the MEP industry. Therefore, this research has formulated an algorithm for optimum module identification in MEP systems, considering the installation cost and the functional requirements of the system. The structured modularisation process developed in the thesis, identifies the optimum module configuration to achieve minimum installation cost, while satisfying the installation and operation constraints of MEP systems. This method assists engineers and researchers to evaluate the benefits of a modular configuration compared to conventional site build strategy, prior to implementing prefabrication in MEP projects. In order to achieve these objectives, three case study project sites were visited during the construction period to identify the constraints in MEP construction and aspects to consider in the modularisation process. Chilled water central plants are chosen for the development of the modularisation algorithm, due to its complex installation process and popularity in the industry. This practical insight into the development of the method ensures that the configurations generated using the algorithm are practically constructable onsite. Structured modularisation methods practiced in various manufacturing industries such as Aerospace, Automotive, Shipbuilding and Consumer electronics were studied to identify their applicability to the construction industry. The developed structured modularisation method presented in this thesis is the only study available to date in literature, that takes an algorithmic approach to modularisation in the construction industry. An automated process of module identification, using a combination of fuzzy logic, Dependency Structure Matrix (DSM) and Hierarchical Clustering and Partitioning Algorithm (HCPA) have minimum human intervention, where input data is extracted from the Building Information Model (BIM). This leads to significant time and cost savings during the design and construction stages of MEP systems. Although the development of the algorithm was based around chilled water plant construction, the methods proposed in this thesis can be used for modularisation of other MEP central plants, such as generator, transformer and pumps, with further research on limitations and assemblies associated with a particular system. In addition to a structured method for modularisation, design engineers and researches would also require a model to evaluate the benefits of modular over conventional construction. In this regard, the output of the developed algorithm estimates the installation cost of the optimum configuration and compare the cost benefits with the conventional case, prior to implementing modular construction in MEP projects. This thesis provides a comparison of the modular approach to conventional construction, to identify a hybrid strategy to MEP plant construction. Furthermore, recommendations are provided to implement this research in other disciplines in the modular construction industry.