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(2007)ThesisThe use of high performance concrete in construction has been enhanced by the use of pozzolanic materials. However, the use of these materials has not been optimized. Such optimization may be achieved by a systematic increase in the amount and combination of pozzolanic material additions, with accompanying studies of their effects on the mechanical, durability and microstructural characteristics of blended concrete. This work evaluated various concrete durability issues by studying systematic increases of pozzolanic materials such as fly ash and blast furnace slag (BFS) in the range of 25, 50 and 70%, and silica fume at 10% of total cementitious materials, forming various binary and ternary concrete blends. The concrete specimens were cured for a period of seven days after demoulding in line with widely practiced commercial curing procedures. The research explored the role and effectiveness of various binary and ternary blends of pozzolanic materials on the mechanical, durability and microstructural characteristics of concrete. Durability was evaluated by two independent rapid chloride permeability tests measured as charge passed and chloride conductivity from the RCPT and UCT tests respectively. These two rapid tests were coupled with long-term ponding tests to evaluate chloride ingress and the extent of corrosion for a period of two years. Further durability tests such as carbonation, drying shrinkage and porosity of these blends were also undertaken. This study also utilized micro-analytical techniques such as X-ray diffraction and Scanning Electron Microscopy to follow the hydration mechanism in various binary and ternary blends. Statistical significance testing was used to analyse and confirm all experimental results and conclusions. It is well known that a level of caution is exercised in the construction industry in the use of ternary blends. This study aims to evaluate the durability aspects of ternary concrete blends, in addition to binary blends, for resistance to chloride, corrosion, carbonation attacks and provide recommendations relating to the limits of blending level, as well as exposure conditions for blended concretes, based on the results of this study. It is expected that this will fill a major knowledge gap observed in the concrete industry. A comparison of two rapid chloride permeability tests such as UCT and RCPT indicates that the UCT test is easy and practicable, and does not contradict results obtained in the standard RCPT. However, the statistical significance of results obtained for some blends was only able to be established by using the RCPT. This effect can be attributed to the larger size specimens compared to UCT. The recommended blend to acquire both early-age and long-term strength development in fly ash is the ternary blends comprising 10% silica fume and 25% fly ash cast using lower w/b ratio. In addition, the same blend exhibited lower carbonation depth, lower charge passed from RCPT, lower chloride ingress and higher corrosion resistance characteristics from long-term ponding test compared to other blends of fly ash. In BFS blends, an increase in compressive strength was observed only in the specimens of 25% BFS compared to other higher percentage blends, while the higher addition of 50 and 70% replacement showed no significant difference in compressive strength between them and their corresponding ternary blends with addition of silica fume. The results of this study indicate that control (OPC) specimens cast with increased w/b ratio of 0.48 showed higher chloride ingress compared to both binary blends of 70% fly ash and 70% BFS specimens. This indicates that (OPC) cast using higher w/b ratio is to be avoided in chloride environments. On the other hand, though, the ternary blends of 10% silica fume and up to 50% fly ash exhibited lower chloride ingress compared to their respective binary blends of fly ash. However, these ternary blends exhibited lower compressive strength, more negative corrosion potential and higher corrosion rate, compared to the respective binary blends of 25% fly ash and its ternary blends. Therefore, the recommended blend observed in the long-term ponding test is the ternary blend of 25% fly ash and 10% silica fume. The recommended level of corrosion resistance in slag specimens is achieved by the use of ternary blends comprising silica fume at 10% added to the blend that contains up to 70% slag. However, the recommended level of slag for a lower carbonation effect is the use of a ternary blend comprising 50% slag and 10% silica fume (3B5S1) which showed a carbonation depth of 10.8 mm and a compressive strength of 53.2 MPa after 365 days of exposure. The drying shrinkage of concrete increased with the increase in fly ash and the same trend was observed in BFS specimens. However, the results were not significantly different between their respective blends. The extent of carbonation in fly ash specimens was higher compared to BFS blends specimens. This can be attributed to the formation of dusty and weak surfaces on the outer surface in addition to the excessive leaching of sodium chloride solution from the long-term ponding test in the former specimens compared to later. The high volume pozzolanic materials, irrespective of fly ash or BFS and addition of silica fume (70% fly ash and 10% silica fume, and 70% BFS and 10% silica fume), showed higher cumulative pore volume indicating that these blends with seven days of curing were not beneficial. These high volume ternary blends required prolonged curing to release portlandite from the hydration of cement to continue the pozzolanic reaction. This study has shown that 7-days curing of the pozzolanic concrete is inadequate if pozzolanic activity is to be invoked. This is particularly the case when it is expected that the concrete is likely to be subjected to a harsher than usual environment characterised by a dry atmosphere.
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(2007)ThesisThe ability of jurors and juries to comprehend and utilise scientific evidence in Australian criminal trials has been examined. From mock jury surveys relating to DNA profiling evidence, it was determined that most respondents were able to comprehend some basic and applied statistics, although their ability was in part related to their knowledge of English and their level of education. The point at which mock jurors were prepared to convict an accused solely on the basis of DNA profiling evidence was examined and found to be low compared with the strength of DNA profiling evidence commonly presented in Australian courts. Mock jurors also demonstrated the ability to process evidence that was presented in a Bayesian framework; commencing with prior odds, introducing new information and culminating in posterior odds. From a survey of Australian forensic scientists, including fraud investigators, it was found that most practitioners' concerns could be addressed by greater pre-trial consultation between experts and legal advocates. Improved knowledge within the legal profession concerning the jargon, principles, procedures, limitations and conclusions to be drawn from different scientific disciplines, prior to presenting this evidence in court, is recommended as the means by which complex evidence can be better adduced from expert witnesses and better presented to juries in criminal trials. Finally, from interviewing actual jurors in criminal trials in the Australian Capital Territory it was determined that where jurors' expectations of scientific evidence, particularly DNA profiling evidence, are not met, high levels of juror frustration and speculation may culminate in hung juries. The adversarial setting of criminal proceedings was also found to produce an environment in which jurors felt that information that would assist them in reaching a verdict was being deliberately withheld. The ability of the jury to ask questions and the allowed nature of those questions were also examined, with the resultant recommendation that juries be given more explicit information at the commencement of trials to inform them about their rights and obligations when asking questions.
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(2006)ThesisThe study of stable, channelled, upland swamps is relatively new and the processes by which they attain and maintain stability are of particular interest. Channels can adjust three elements of their morphology: cross-section, bedform and planform. This thesis examines unusual extremes in the adjustment of these elements in several swamp channels at Barrington Tops, New South Wales. In these channels, high bank strength is afforded by dense vegetation that has enabled the channels to achieve unusually low width/depth ratios. The resultant at-a-station hydraulic geometry is such that width barely increases with flow stage, depth increases moderately and velocity increases markedly; the channels have particularly high hydraulic efficiencies. Shear stress calculations suggest that bankfull flows are more than capable of transporting the scant sediment with which they are supplied. This economic use of energy means that, to maintain equilibrium, the excess must be consumed by the remaining elements; bedform and planform. Bedform magnitude (steepness) is strongly linked to flow resistance and there are large variations in the scale of bedforms between the channels studied here. In the smaller but more sinuous Polblue Creek, power is moderate and bed features display moderate steepness values. In contrast, the larger but less sinuous Barrington River and Edwards Creek channels have higher stream powers and their armoured bedforms have developed with much greater steepness. The considerable turbulence associated with these larger features are unable to destabilise the highly resistant channel banks but are sufficient to generate energy losses that reduce grain shear-stresses and prevent bed erosion. Polblue Creek, Barrington River and Edwards Creek have each developed sinuous planforms, with some examples of very tight bends. The reduction in the energy slope associated with planform development and the substantial turbulence that these tight bends generate combine with bedform development to counter the exceptional hydraulic efficiency of the channel cross-sections. The development of extreme bedform and planform morphologies have enabled system stability, despite high shear stresses and limited energy expenditure on sediment transport. This research suggests that bed armouring, high bank strengths and the development of highly sinuous planforms are integral to the maintenance of channel equilibrium, as has been demonstrated by channelled-swamp stability over the last ~1ka.
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(2008)ThesisThe household has always been a place of information consumption. While much is known about the modern household as a consumer of information and adopter of information-related technologies, virtually nothing is known about how the household -as a collectivity - processes and manages its information. This research represents the first systematic study of the household as a human information system and presents an understandingtype theory of household information practices. Using dimensional analysis (including theoretical sampling) as proposed by Schatzman (1991), the information practices of eleven households (28 householders) were explored. Each householder completed a questionnaire to identify the information and information-related devices and services used in the household. This was followed by an unstructured group interview that explored the information practices in the household. Analysis of the questionnaires and interviews revealed that within a household it is individual householders who process and manage information. They do so because information has a role in their life, that is, particular information is meaningful for them. Each householder thus devises their own individual information practices, representing the unique way in which a householder comes to live with information. Household information practices are the sum of these individual information practices. They are mediated by two enabling processes - taking charge and negotiating - and nine dimensions of action. Six of the dimensions affect the information practices of individual householders - which are themselves a dimension - while the final two represent, respectively, the consequences of living with and without information. All processes and dimensions operate against, and interact with, a changing structural context of information, technology and society. As a result, each household has a characteristic mode for dealing with information. The centrality of negotiation in developing household information practices indicates that the practices are socially constructed and represent an emergent phenomenon. This, in turn, suggests that the household as an information system is a negotiated order. Insights from the research can be applied to other types of organisations and other aspects of the Information Systems discipline. Areas of further work are identified to expand upon the exploratory nature of this research.
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(2008)ThesisThe thesis deals with the design and implementation of an Adaptive Flight Control technique for Unmanned Aerial Vehicles (UAVs). The application of UAVs has been increasing exponentially in the last decade both in Military and Civilian fronts. These UAVs fly at very low speeds and Reynolds numbers, have nonlinear coupling, and tend to exhibit time varying characteristics. In addition, due to the variety of missions, they fly in uncertain environments exposing themselves to unpredictable external disturbances. The successful completion of the UAV missions is largely dependent on the accuracy of the control provided by the flight controllers. Thus there is a necessity for accurate and robust flight controllers. These controllers should be able to adapt to the changes in the dynamics due to internal and external changes. From the available literature, it is known that, one of the better suited adaptive controllers is the model based controller. The design and implementation of model based adaptive controller is discussed in the thesis. A critical issue in the design and application of model based control is the online identification of the UAV dynamics from the available sensors using the onboard processing capability. For this, proper instrumentation in terms of sensors and avionics for two platforms developed at UNSW@ADFA is discussed. Using the flight data from the remotely flown platforms, state space identification and fuzzy identification are developed to mimic the UAV dynamics. Real time validations using Hardware in Loop (HIL) simulations show that both the methods are feasible for control. A finer comparison showed that the accuracy of identification using fuzzy systems is better than the state space technique. The flight tests with real time online identification confirmed the feasibility of fuzzy identification for intelligent control. Hence two adaptive controllers based on the fuzzy identification are developed. The first adaptive controller is a hybrid indirect adaptive controller that utilises the model sensitivity in addition to output error for adaptation. The feedback of the model sensitivity function to adapt the parameters of the controller is shown to have beneficial effects, both in terms of convergence and accuracy. HIL simulations applied to the control of roll stabilised pitch autopilot for a typical UAV demonstrate the improvements compared to the direct adaptive controller. Next a novel fuzzy model based inversion controller is presented. The analytical approximate inversion proposed in this thesis does not increase the computational effort. The comparisons of this controller with other controller for a benchmark problem are presented using numerical simulations. The results bring out the superiority of this technique over other techniques. The extension of the analytical inversion based controller for multiple input multiple output problem is presented for the design of roll stabilised pitch autopilot for a UAV. The results of the HIL simulations are discussed for a typical UAV. Finally, flight test results for angle of attack control of one of the UAV platforms at UNSW@ADFA are presented. The flight test results show that the adaptive controller is capable of controlling the UAV suitably in a real environment, demonstrating its robustness characteristics.
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(2008)ThesisHistorians have largely ignored the importance of relationships in war, particularly at a grass roots level. Examining the past from a relational point of view provides a new perspective on war not accessible through other forms of analysis. A relational approach to a study of the campaigns in Greece and Crete helps to explain, amongst other issues, why so many Australian lives were saved. Australians entered Greece with little background knowledge of the country and the people they were required to defend. There was no serious consultation with the Australian government apart from the cursory briefing of its Prime Minister. Although Britain had numerous intelligence officers operating on the ground in Greece prior and during the campaign, little information about the true political situation in the country had filtered through to the Australian high command. This placed the troops in a very vulnerable position on the Greek frontier and, later, on Crete. Military interaction with the Greeks proved difficult, as key officers from the Greek General Staff and senior government ministers did not intend to fight the Germans. As a result, little coordination took place between the Australian and Greek forces hindering the development of a successful working relationship. Conversely, relations with the Greek people were very amicable with many Greeks risking their lives to help Australian troops. The altruism of the Greeks was one of the most striking features of the Greek and Crete campaigns. Unlike Egypt, where the Australians felt alienated by the values and customs of the Egyptian people, in Greece they warmed to the behaviour of the Greeks. Although they did not speak the same language nor share a similar culture, they had many characteristics in common with the Greeks whose strong sense of loyalty to their allies really impressed the Australians. On their part, the Australians displayed respect for the values and customs of the Greek people. Through their interaction during the war, the Greeks came to regard the Australians, not only as friends, but also as brothers, forging an intimate relationship that has been incorporated in the social memory of both countries.
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(2008)ThesisApplication-layer overlay networks have recently emerged as a promising platform to deploy additional services over the Internet. A virtual network of overlay nodes can be used to regulate traffic flows of an underlay network, without modifying the underlay network infrastructure. As a result, an opportunity to redeem the inefficiency of IP routing and to improve end-to-end performance of the Internet has arisen, by routing traffic over multiple overlay paths. However, to achieve high end-to-end performance over the Internet by means of overlay networks, a number of challenging issues, including limited knowledge of the underlay network characteristics, fluctuations of overlay path performance, and interactions between overlay and the underlay traffic must be addressed. This thesis provides solutions to some of these issues, by proposing a framework to construct a multi-path overlay architecture for improving Internet end-to-end performance and availability. The framework is formed by posing a series of questions, including i) how to model and forecast overlay path performance characteristics; ii) how to route traffic optimally over multiple overlay paths; and iii) how to place overlay nodes to maximally leverage the Internet resource redundancy, while minimizing the deployment cost. To answer those research questions, analytical and experimental studies have been conducted. As a result, i) a loss model and a hybrid forecasting technique are proposed to capture, and subsequently predict end-to-end loss/delay behaviors; with this predictive capability, overlay agents can, for example, select overlay paths that potentially offer good performance and reliability; ii) to take full advantage of the predictive capability and the availability of multiple paths, a Markov Decision Process based multi-path traffic controller is developed, which can route traffic simultaneously over multiple overlay paths to optimize some performance measures, e.g. average loss rate and latency. As there can be multiple overlay controllers, competing for common resources by making selfish decisions, which could jeopardize performance of the networks, game theory is applied here to turn the competition into cooperation; as a consequence, the network performance is improved; iii) furthermore, to facilitate the deployment of the multi-path overlay architecture, a multi-objective genetic-based algorithm is introduced to place overlay nodes to attain a high level of overlay path diversity, while minimizing the number of overlay nodes to be deployed, and thus reducing the deployment cost. The findings of this thesis indicate that the use of multiple overlay paths can substantially improve end-to-end performance. They uncover the potential of multi-path application-layer overlay networks as an architecture for achieving high end-to-end performance and availability over the Internet.
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(2008)ThesisThis thesis examines the origins and development of signals intelligence in the Royal Australian Navy, during the period 1914 to 1945, within the context of an Australian contribution to Imperial defence. In doing so it demonstrates how the development of this capability was shaped by national, Imperial and international forces and events. The thesis thus fills a gap in the historiography of imperial defence and of early twentieth century signals intelligence. It also constitutes a case study of the development of a niche military capability by a small to medium power in the context of great power alliances and major historical events. The thesis is based principally upon the investigation of documents in the Australian, US and UK national archives, some of which have been newly declassified for this purpose. During the First World War the RAN undertook a minor cryptographic effort focused on intercepting and breaking coded messages from the German Pacific Squadron. After the War, and at the request of the RN, the RAN began to develop a signals intelligence capability aimed at the Imperial Japanese Navy. This capability was seen as part of the RAN contribution to Imperial defence. The commitment, made without Australian political approval, would see the RAN conduct two covert intelligence collection operations against the Japanese Mandated Territories. After the Japanese attack on Pearl Harbor and subsequent defeat of the Western Powers in Asia, the RAN signals intelligence organisation became, as a consequence of agreements between Britain and the USN, part of the USN organisation in the Pacific. At no stage however, was the RAN involved in the discussions which accompanied these arrangements nor did it have any subsequent say in the strategic direction of this capability. As a consequence, when the Pacific War was drawing to a close the future of the RAN's cryptographic organisation came in to question. By the time the Japanese surrendered this issue had still not been resolved. Beyond the history of the origins and development of signals intelligence in the RAN, and of its involvement in the signals intelligence war against Japan, the thesis highlights the importance of committed individuals in small military organisations and how they can greatly influence the success or otherwise of these organisations. The ability of personnel from different nations to work together in signals intelligence is reflective of the functioning of the alliance as a whole. The development of such a niche capability by a small to medium power can have an effect on that nation's standing, in the context of alliance relationships, as it did in this case. As the RAN found however, such capabilities do not provide for automatic access to strategic decision making within an alliance.
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(2007)ThesisThe intent of this study is to assess the role of fundamental Japanese security policy objectives in driving the significant shifts in Japan s approach towards missile defence cooperation with the United States from 1993 to 2003. In studying the relative influence of the objectives that guided Japan s approach towards missile defence cooperation, this thesis seeks to address a gap in the literature. A debate has occurred over the direction of Japanese security policy that is based on widely different assumptions on the importance attached to various fundamental security objectives. At the same time, Japan s approach to missile defence has been the subject of considerable analysis that identified the crucial importance of the issue for the attainment of these fundamental security policy objectives. But no linkage has been established between these two levels of analysis. In particular, there has been an absence of assessments of what Japan s decisions on missile defence cooperation indicate about the relative influence of the various objectives. This thesis developed an analytical framework to enable such an assessment by examining the structure of missile defence cooperation undertaken. Japan possessed a range of options in the level and type of involvement in missile defence cooperation. That involvement would determine the eventual type of benefits and costs incurred against the affected objectives. Cooperation agreed to (or rejected) over the ten year period thereby provides a means to determine the influence of key objectives on Japan s approach, and in particular those objectives that restrained involvement. The thesis finds that a clear hierarchy existed in the influence of the various objectives on Japan s approach with changes in their influence explaining the evolution of Japan s commitment. The desire to strengthen the alliance, weakening domestic political constraints, and disregard of China s opposition provide the key explanations. These findings not only point towards the respective strengths and weaknesses of the various approaches employed to explain Japanese security policy, but they also suggest the value of greater attention to the state s ability to overcome domestic constraints in determining policy in order to fully understand the broader transformation of Japanese security policy.