Engineering

Publication Search Results

Now showing 1 - 10 of 61
  • (2006) Arsana, I Made Andi
    Thesis
    The Democratic Republic of Timor-Leste (East Timor) attained independence on 20 May 2002, marking its separation from Indonesia. As a newly independent country, East Timor is faced with a number of significant international opportunities, together with some obligations that it must fulfil, including the delimitation of its international boundaries. Equally, for Indonesia, with 10 maritime neighbours, the delimitation of maritime boundaries is a significant challenge. This research aims to provide a preliminary study on the delimitation of the Indonesia - East Timor maritime boundary, with a focus on technical aspects. Geospatial data has been obtained from the Indonesian government and processed with the assistance of a specialised Geographic Information Systems (GIS) application: CARIS LOTS™. The main tasks of this research are to simulate the maritime claims of Indonesia and East Timor, to identify overlapping claims and to delimit the maritime boundaries between the two states. Technically, potential delimitation lines were calculated in a geodetically robust manner. A literature review has been conducted with regard to the principles of maritime boundary delimitation, research on similar cases of maritime boundaries and papers discussing the decision/judgement in some other proceedings regarding maritime boundary delimitation. Existing research and literature are used to support the arguments provided in this current research. The United Nations Convention on the Law of the Sea 1982, LOSC, provides the main legal reference point, along with relevant state practices and jurisprudence. As to the results of this research, it has been identified that three major locations for maritime boundaries are to be delimited. These are in the Ombai Strait, the Wetar Strait and in the Timor Sea. A number of alternative potential boundary alignments have also been examined and analysed for the three locations, in the context of future maritime boundary negotiations between the two States. However, the results are not the final boundaries that Indonesia and East Timor have to accept. Ultimately it is for the governments of Indonesia and East Timor to decide on and negotiate towards an equitable solution that will satisfy both parties. However, it is hoped that this study will contribute to achieving that goal.



  • (2003) Weerasekera, Nilushani Pavithra
    Thesis

  • (2017) Chen, Kai
    Thesis
    Ubiquitous navigation is becoming highly demanded as Location-Based Service (LBS) becomes increasingly popular. In outdoor environments, Global Navigation Satellite System (GNSS) has been developing rapidly over the past few decades. However, indoor navigation is still in its infancy. Compared with other strategies, vision appears to be one of the most promising indoor navigation technologies. Vision sensors are cheap, self-contained and work well for both indoor and outdoor environments. However, there are several elements affecting the performance of vision-based indoor navigation. The measurements for the navigation are image coordinates of Pseudo Ground Control points (PGCPs). These measurements are processed by least squares method with two types of mathematical models. The functional model has been well documented in the literature. However, the stochastic model still presents various challenges and has not been investigated in enough detail. This research focused on dealing with randomised errors existing in navigation steps. Different stochastic models are built to estimate the covariance matrix for image coordinates of PGCPs. These stochastic models have been tested, indicating a significant improvement in the reliability of the position and orientation of the vision sensor. The major research contributions are in the following three different methods to construct a stochastic model: a. Empirical method In the commonly used stochastic model, the variances of PGCP image coordinates are assumed to be the same. However, as the images from the camera can be affected by different variables such as the light, angle, camera parameters and geometric distribution, this assumption is not always accepted. Based on this fact, the measurements should be assigned with different accuracies. Empirically, the closer to the image centre, the more accurate the PGCP image coordinates are. A realistic stochastic model based on the distance between the image features of PGCPs and image centre was constructed to achieve satisfactory positioning results. b. MINQUE method Rao (1970) developed the most commonly used method for estimating variance-covariance components, Minimum Norm Quadratic Unbiased Estimation (MINQUE). It was employed to construct the covariance matrices for PGCP image measurements with the condition that redundant measurements were available. Furthermore, a simplified MINQUE procedure was also used to evaluate the accuracy of measurements. In this research, the efficiency of the estimators was tested using simulated and real PGCP data sets in two different structures of variance component models. Group and additive models were discussed using the rigorous MINQUE method and the simplified MINQUE method. c. BQUE method The Best Quadratic Unbiased Estimator (BQUE), another method for estimating variance-covariance components, was introduced to compare the positioning results with MINQUE by the additive model. However, in MINQUE and BQUE procedure, the estimated variance components may be negative. This is not satisfactory in a real environment. The possible reasons could be a) the adjustment and/or the stochastic models are unreasonable or b) there is not enough of redundancy in the least-squares computation for vision-based navigation applications. To deal with these problems, the Best Quadratic Minimum Bias Non-Negative Estimator (BQMBNE) has been designed to obtain non-negative estimates. The six exterior orientation parameters by these methods were analysed.

  • (2019) Gong, Shuangqing
    Thesis
    Although tourism is one of the main reasons for inter-regional travel, but there are relatively little quantitative models of inter-regional and national-level travel demand developed specifically to explain and simulate its pattern. This research project attempts to answer three questions for the different group of tourists: 1) how long will a tourist spend in a journey? 2) what destinations are the tourist going to select and how much time they spend at each selected destination? also, 3) in which order the tourist visit these selected destinations? A sequential modelling framework is proposed and developed in this study to answer the three issues. A Negative Binomial (NB) model is formulated to model tourists’ length of stay in Australia. A Multiple Discrete-Continuous Extreme Value (MDCEV) model is applied to estimate tourists’ selection on destinations and the allocation of time to each selected destination under the constraint of the time budget. A Mixed Logit (ML) model is developed to model the visiting sequence of the selected destinations. The performances of these three models are evaluated by using the root mean square error and correct ratio metrics. These models are calibrated by the data obtained from the National Visitor Survey (2007) and International Visitor Survey (2012) in Australia. The modelling results show that trip duration and destination selection are affected by age group, origin, income, and employment status. The finding of this research is useful for stakeholders in the tourism industry to better understand domestic and international tourists’ behaviour in Australia and make better policies for improving the service level.

  • (2014) Wang, Ke
    Thesis
    Tropical cyclone (TC) and flooding are global catastrophes, devastating natural disasters. Synthetic aperture radar (SAR) satellite images present unique capabilities of cloud penetration, from signal response of sea/ground surface backscatter. The availability of high spatial resolution SAR satellite imagery shows potential for new metrological and environmental applications. This thesis presents two major case studies detailing efficient approaches in TC eye extraction and water body detection, using data from spaceborne Radarsat-1, Envisat ASAR and airborne Interferometric Synthetic Aperture Radar (IFSAR). In the case study of TCs, using the relationship between normalized radar cross section (NRCS) and backscatter for the roughness of sea surface, SAR images enable the measurement of the areas of TC eyes as an identifiable result. The size and shape of TC eyes strongly corresponds with its evolution and strength. It can play a vital role in monitoring and forecasting the behaviour of TCs by introducing mathematical morphology methods. Skeleton pruning based on discrete curve evolution (DCE) was used to ensure global and local preservation of the TC eye shape, by reducing redundant skeletons caused by speckle noise along the edges of the TC eye. These morphological-based analyses have been employed explicitly for six representative ocean SAR images with different TC patterns. The results demonstrate a high degree of agreement with the area of coverage derived from reference data based on NOAA’s manual work. The second case study for water body detection involves pattern recognition with respect to digital image segmentation. Morphological watershed algorithm is applicable for image segmentation, albeit excessively sensitive to speckle noise in SAR images, leading to over-segmentation and thus a reduction in efficiency. This thesis presents a novel approach for water body extraction from SAR images by applying marker-controlled watershed combined with top-hat transformation. The purpose of this case study is to improve the efficiency of watershed techniques compared with Canny edge detection results for fine resolution IFAR images, and to yield an intuitive and well segmented image for mapping of water body boundaries.

  • (2014) Karna, Barun
    Thesis
    Membrane fouling in reverse osmosis (RO) systems remains a significant operational issue during seawater treatment for potable applications. Specifically, organic and biological fouling caused by the deposition of dissolved organic matter (DOM) and/or growth of microorganisms in RO systems is a major problem, despite the low concentration of these compounds (at 1-4 mg L-1 as C), compared with the other chemical constituents present in seawater (e.g. dissolved salts at 25-50 g L-1). Hence, pre-treatment of DOM remains a key issue influencing operation and maintenance costs in RO systems. Dissolved air flotation (DAF) has recently received attention as a potential pretreatment option for seawater, since this process has been used extensively in freshwater situations to remove low density particles such as algae, colloids and DOM. However, there have been limited investigations in its application to seawater. Furthermore, such investigations have been hampered by the difficulty in characterising DOM in seawater, due to the high salt content and low carbon concentration. In this study, a model seawater solution was prepared, using six model organic compounds that have been shown to be present in seawater, to develop and validate fluorescence excitation emission matrix (FEEM) and liquid chromatography with organic carbon detection (LC-OCD) analytical methods. These methods were then used to characterise real seawater. Subsequently, these analytical techniques were applied to assess the performance of DAF under varying coagulation conditions for removing DOM from the model seawater and a number of real seawater samples. Once the methods were optimised, both LC-OCD and FEEM were able to provide detailed information on the concentration and character of the low concentrations of DOM in saline environments and to assess the DAF performance. On DAF treatment of model solution and seawater samples, the biopolymer and humic substance fractions were the major organic fractions removed at 42-98% and 20-95%, respectively. Humic acid removal increased at low pH (5-6) which was observed generally to be the optimal operating pH. The normalised coagulant dose (Fe3+/DOC ratio) required for successful coagulation was observed to be between 0.5-4 at pH 5.5, increasing to 4-12 at pH 7.5.

  • (2017) Alac Barut, Ruken
    Thesis
    In 1999, the Izmit Earthquake struck Istanbul and its surroundings in northwest Turkey. It was one of the most devastating earthquakes of the twentieth century, significantly impacting on 20 million inhabitants and nearly half of the country’s industry. The earthquake’s epicentre was located on the North Anatolian Fault (NAF) which is one of the most active right-lateral strike-slip fault. Because of its importance for the tectonics of Marmara region, the Izmit earthquake has attracted the interest of several scientist to study the surface deformation during earthquake cycles. This study examines the Izmit earthquake using Interferometric Synthetic Aperture Radar (InSAR) with Global Navigation Satellite System (GNSS) and Coulomb Stress Change Modelling. Since the InSAR and GNSS techniques are sensitive to displacement , the technique is very efficient to measure “earthquake deformation” phenomenon. Moreover, by combining these techniques with Coulomb Stress Change Modelling, the understanding of complex deforming zones can be improved. From a joint analysis of InSAR, GNSS and Coulomb Stress Modelling techniques, the interseismic, coseismic and postseismic deformation of the 17 August 1999 Izmit earthquake have been determined in terms of stress progression and displacement. The results of the research show that there is an apparent correlation between the InSAR, GPS and Coulomb Stress Change Modelling results, which contribute to the identification of the Izmit earthquake characteristics. It shows that the Izmit earthquake caused the northern part of the NAF to move in an easterly direction and the southern part to move in a westerly direction. This partially explains the fault extended westwards of the surface faults, underneath of the Gulf of Izmit. In addition, this westerly movement changed the stress distribution and increased the deformation around the fault zone. The conclusion can also be drawn that combination of these three techniques can improve the understanding of the behaviour of the earthquakes and highly damaged areas. Following an in-depth multi-dimensional analysis of research results, recommendations for hazard mitigation can also be presented.

  • (2015) Mac, Thi Ngoc
    Thesis
    A unified bounding surface viscoplasticity model is developed to describe the stress-strain time-dependent behaviour of soils using the consistency viscoplastic theory. Unlike the overstress based models, the elasto-viscoplastic model proposed meets the consistency condition, and allows smooth transition from rate-independent elastoplasticity to rate-dependent viscoplasticity. In the model proposed, the yield function is defined as a function of strain and strain rate parameters. This means the yield surface can expand and shrink not only by hardening or softening effects but also by strain rate effects. Two solutions, i.e. analytical and numerical are proposed for the derivation of viscoplastic multiplier with relevant assumptions in order to obtain the relationship between stresses and viscoplastic strains. A non-associated flow rule is used to generalise application of the model to all types of soils. A new hardening parameter, namely the strain rate hardening parameter, is introduced to account the rate dependency in the model. This strain rate hardening parameter (𝜉) is defined as a function of the strain hardening parameter (ℎ). The essential elements of the model are validated by comparing numerical results with the experimental data from the literature. Application of the bounding surface viscoplasticity model to predict the stress-strain behaviour of fully saturated soils are demonstrated for undrained creep and undrained constant strain rate tests. Several numerical examples are also presented to illustrate the time-dependent behaviour of cohesive and non-cohesive soils subjected to a wide range of monotonic loadings in both drained and undrained conditions.