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(2021)ThesisPlasmonic is an emerging technology used to increase the performance of thin-film devices via light-trapping mechanisms. Recently, plasmonic devices have been used due to their nanoscale fabrication abilities. Metamaterials are promising candidates for improving the light absorption of plasmonic devices. The extraordinary properties of metamaterial-plasmonic devices (such as the perfect absorption of light) open up applications such as solar energy harvesting, photo-detecting and making batteries. This thesis focuses on the theoretical design and experimental studies of metamaterial-based perfect absorbers (MMPA) to improve their optical properties and applications (e.g., energy harvesting). I also design a high-power MMPA for high-power laser applications. First, I present the design and analysis of a high-power broadband perfect absorber. An array of rectangular patterns was placed to broaden the bandwidth so that the array can function between 950 nm and 1400 nm. Here, I propose a tungsten boride (a refractory ceramic) broadband metamaterial absorber and characterize its optical properties numerically and experimentally. I have also analyzed the damage characteristics of this absorber using a femtosecond laser and compared these with an ordinary gold metamaterial absorber. Second, a multilayer-based perfect absorber for omnidirectional capabilities is theoretically and experimentally analyzed. The device provides a reasonable amount of light absorption and thermal stability has been checked. Applying this device to high-temperature solar cell applications is discussed. I demonstrate a thermally stable broadband absorber based on an ultrathin layer of refractory ceramic, tungsten boride. I experimentally analyze and compare the performance of the absorber with an aluminum-based absorber. The multilayer perfect absorber has absorption higher than 85% in the wavelength range between 500 and 1600 nm over a large range of incident angles (up to 60 degrees). I show that a tungsten boride absorber has significantly better temperature stability compared to its aluminum counterpart, achieving stable operation at temperatures up to 270 ℃. These absorbers may have applications in solar thermophotovoltaic energy conversion. Third, a square hole structure is proposed, where a lossless silica dielectric material is combined with MnO2 materials. Then, the geometric parameters of this structure are numerically optimized at the desired application. An adequate choice of parameters, shape and the proper combination of materials can lead to an electrically tuneable metasurface. The structure can produce a 25% change of transmission with the applied electric power. Finally, I numerically analyzed and experimentally characterized Kevlar fabrics for the application of personal heat management. Heat management is essential for human comfort. In recent years, passive radiative cooling through heat transfer to outer space has been extensively studied. Personal temperature control is used to control the temperature of objects beyond the local environmental temperature. I show that Kevlar fabrics are transparent to mid-infrared human body radiation but opaque to visible light. Here, I have experimentally investigated the optical and thermal properties of Kevlar fabrics, which can have 90% emissivity in the mid-infrared region and produce a 2.6 ℃ temperature drop. I processed a Kevlar textile that promotes effective radiative cooling while retaining sufficient air permeability, water-wicking rate, and mechanical strength for wearability. The Kevlar fabric is an effective and scalable textile for personal thermal management.
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(2021)ThesisA handful of technologies have had a profound influence on the course of human history. The most influential have transformed society by recasting the social, political, economic and military norms of the age. Another transformation is presently underway, driven by the influence of computation, artificial intelligence, biotechnologies and nanotechnologies behaving as General Purpose Technologies. This change constitutes a Fourth Industrial Revolution with enduring consequences for all aspects of modern society. Anticipating transformational change is a prerequisite for adequate preparation. The Australian Army is preparing for an increasingly uncertain future in which emerging technologies, domain fusion and accelerating rates of change will produce disruptive discontinuities in military power. While the Army is aware of the magnitude of change it faces, it remains poorly positioned to adapt, let alone thrive. The Australian Army needs to prepare for a future where successive waves of technology influence society. This influence will change societal expectations governing how military power is applied, while concurrently disrupting the methods available to apply military force. This study assesses organisational adaption to these change pressures through the lens of military transformation theory. Military Revolutions theory describes transformational societal conditions alongside the potential for one or many Revolutions in Military Affairs to profoundly influence military power. The Australian Army is not prepared for either, preferring traditional approaches to modernisation that replace existing equipment with expensive upgrades. This approach to modernisation is conservative, avoiding the risk of uncertain conditions, but in doing so sets the conditions for a future crisis. The Australian Army can adequately prepare for the conditions ahead, but it must be willing to challenge long held beliefs. Balancing sustaining and disruptive forms of innovation is key to competitiveness in the present and future. New structures and a culture that supports all forms of innovation will allow the Army to thrive in the design competition which will characterise military preparedness in the Fourth Industrial Age.
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(2021)ThesisHost-guest systems incorporating various luminescent transition metal (TM) complexes as guests with cucurbit[10]uril (Q[10]) as host have been assessed. It has been found that hydrophobic effect is the dominant factor driving the association, while other factors such as overall size and charge of the guest have smaller influence on the binding modes or affinity. A systematic investigation of the effect of the host-guest interaction on the photophysical properties revealed a strong dependence on the electronic structure of the particular TM complex guest. Archetypal tris-polypyridyl TM complexes Ru-1 {[Ru(bpy)3]2+}, Ru-2 {[Ru(phen)3]2+}, Ir-1 {[Ir(bpy)3]3+} and Ir-2 {[Ir(phen)3]3+} (where, bpy = 2,2′-bipyridine and phen = 1,10-phenanthroline) were studied as guests with the host Q[10]. Larger phen-containing complexes showed greater affinity for Q[10], and changes in emission intensity were greater compared to the corresponding bpy complex. Molecular modeling showed that encapsulation by Q[10] caused distortion of the metal-ligand bonding framework, which, for the Ru(II) complexes, could lead to a reduced energy gap with a higher lying non-emissive state. Ir(III) and Ru(II) cyclometalated and Re(I) tricarbonyl TM complexes were also studied as a guest with the large host Q[10]. The guest complexes were as follows: Ir-P {[Ir(ppy)2(phen)]+}, Ir-DtBB {[Ir(ppy)2(dtb-bpy)]+}, Ir-bb5 {[{Ir(ppy)2}2(µ-bb5)]2+}, Ru-H {[Ru(bpy)2(ppy)]+}, Re-P {[Re(CO)3(phen)(py)]+}, and Re-TMP {[Re(CO)3(Me4phen)(py)]+} (where ppy = 2-phenylpyridyl, dtb-bpy = 4,4′-di-tert-butyl-2,2′-dipyridyl, bb5 = 1,5-bis[4-(4′-methyl-2,2′-bipyridyl)]-pentane, Me4phen = 3,4,7,8-tetramethyl-1,10-phenanthroline and py = pyridine). The binding preference in mononuclear cyclometalated complexes was not changed by the introduction of hydrophobic groups on the polypyridyl ligand, but the dinuclear complex Irbb5 did show an alternative mode of association for the metal centers. All complexes showed enhancement of emission intensity, with the extent of this being dependent on the nature and proximity of higher lying states, and the orientation of the metal center inside the cavity of Q[10]. Q[10] showed ability to differentiate between diastereomers of Irbb5 by NMR spectroscopy. The photochemically active guest molecules Ru-1, Ru-3 {[Ru(bpy)2(H2O)2]2+}, Ir-Cl {[Ir(phen)2Cl2]+} and its photoproducts Ir-A {[Ir(phen)2(H2O)2]3+} and Ir-B {[Ir(phen)2(OH)2]+} were investigated with Q[10]. Results showed that Q[10] binding may either enhance or inhibit photochemistry, depending on the particular TM guest complex and the overall reaction mechanism.
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(2022)ThesisThe limited scholarship concerning New Zealand’s military forces in the decades before the First World War has identified the strategic and imperial reasons for the military reforms of 1909. This thesis employs a ‘new military history’ or ‘war and society’ approach that recognises military and non-military reasons. While the post-1909 military system sought to create a pool of trained men who would volunteer for service overseas, it also needed to address the public’s expectation that training would mitigate perceived societal shortcomings. Thus, New Zealand’s citizen soldiers were more than a military force. The decades around the turn of the twentieth century saw profound changes in social values, the economy, demographics, communications and attitudes in New Zealand. Respect for military service, muscular Christianity and social Darwinism grew, as did concerns about urban youths. A new attitude to the empire and its defence developed. By the mid 1910s the public were increasingly insistent that broadly inclusive military training would remedy the decline in the behaviour, attitudes and physical condition of young males. In 1907 the New Zealand government began to accept that its support for imperial defence needed to be more than vocal. Prime Minister Ward’s 1909 decision to donate a battleship to the Royal Navy was applauded by the public. His intimation that the volunteer system might be replaced with compulsory or universal military training met with warm approval. For the first time in decades military and naval matters dominated public discourse. The Chief of the Imperial General Staff informed Ward that wholesale military reforms in New Zealand were required. Thus, government acceptance that it needed to make a tangible contribution to imperial defence, an empire-minded public, advocacy of military training for social remediation reasons, and professional military opinion led to the Defence Act of 1909. The operation of the new military system has been overlooked in the historiography. Sections of the public became upset that only half of those liable for training received it and that one-third of trainees were prosecuted in criminal courts for Defence Act offences while the vast majority of those who did not or refused to register did so with impunity. In 1914 it became clear that the territorial system would not provide the balanced force of trained volunteers as intended. Territorials were, however, relatively well-trained, five times more likely than non-territorials to volunteer for expeditionary service, and the staff and administrative systems that had been established proved effective. New Zealand’s post-1909 military system had two aims: social remediation and to deliver a trained expeditionary force. It was partially successful at both.
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(2019)ThesisAt the turn of the twentieth century in Australia and New Zealand, the question of women’s right to the franchise was hotly debated. Historians have addressed evidence such as records of political debates and journalism to elucidate the arguments suffragists and their opponents used to further their respective aims, and literary scholars have shown how each country’s literature contributed to discourses about women’s position in society more broadly. A thorough investigation of the literary manifestation of the women’s suffrage movements in the Tasman region has, however, not yet been undertaken. This thesis sets out to fill this lacuna by, firstly, determining the scope of Australian and New Zealand literature about women’s rights to political citizenship, and, secondly, by investigating the ways in which literary form interacted with politics to render enfranchised woman and her impact on society in an imaginative space. An analytical survey of accessible literature, including novels, short stories, poetry, and fictionalised letters, this thesis finds startling diversity in the aesthetic qualities of literature about women’s suffrage from the Tasman region. Identified works are variously and sometimes simultaneously argumentative, sincere, parodic, didactic, and ironic, and the question of enfranchised womanhood is most often entangled in wider social debates. The wider debates to which these texts attend are framed by contemporary generic trends, but each text tests the bounds of genre in different ways. To elucidate how their literary features can delimit these texts’ political imaginings, this thesis takes genre as its structuring principle. Categorised according to realist, romantic, and speculative genre traits, the literature selected for discussion showcases the dynamic interaction of literary genres and the political function of such work. The scarcity of contemporary reviews necessarily limits claims about the impact of literature about women’s suffrage on debates about women’s political citizenship. Yet, by drawing on the theoretical schema of thinkers Rita Felski, Martha Nussbaum and Ross Gibson, this thesis argues that the influence of literature about the franchise for women resonates across time and can illuminate the feminist pasts of Australia and New Zealand, while equipping us with the tools to thoughtfully confront the future.
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(2022)ThesisThe increase in waste disposal increases the demand for better design, construction, operation and management of the landfills. A common method to accelerate the decomposition, stabilization and settlement of municipal solid wastes (MSWs) is leachate recirculation. However, slope failure occurs due to the poor design and management of the recirculation and gas collection systems, together with the change in the geotechnical properties of MSWs due to decomposition. Based on the field compositions at a working cell in Mugga Lane Landfill, ACT, Australia, a series of experiments have been conducted to study the effects of leachate exposure on the geotechnical properties of MSWs with different compositions. The experimental programs include compaction, saturated hydraulic conductivity, direct shear, consolidated undrained triaxial shear and one-dimensional consolidation. Following this, fresh waste samples with different compositions were prepared in the simulators and recirculated with water or leachate to enhance the biodegradation. The samples with the same dry unit weights but different degrees of biodegradation (DOB) were tested to address the effects of decomposition on the geotechnical properties of the MSWs. Despite of the change in the composition and particle sizes, the variation in the leachate properties significantly affects the geotechnical properties of the MSWs. Three small laboratory scale and one larger laboratory scale, and four field scale bioreactors were set up in the laboratory or landfill site. The objectives are to investigate the effects of initial compaction, recirculation liquids and rates, loading levels and environmental temperatures on the long-term physical, mechanical and biochemical behaviours of the MSWs. The measured and analyzed properties include the settlement, initial creep, bio-compression and residual creep ratios, quantity and quality of leachate generation, rate and concentration of methane generation. A new equation was developed to capture the change in the methane generation rate with time. Further experiments were conducted to evaluate the water retention curves (WRCs) of MSWs under different degrees of biodegradation, dry unit weights and paper contents. Fresh MSW samples and soil-paper mixture were compacted to different initial dry unit weights and then decomposed for different periods to the same dry unit weight before testing. It was found that, in addition to dry unit weights of MSW, the effects of decomposition and paper contents on the unsaturated properties of the MSWs depend on the balance between the percentages of biodegradable and highly decomposed components. Two settlement profilers were installed in the landfill site to obtain the settlement of an MSW lift in a working cell of the landfill site. A global navigation satellite monitoring system was installed to monitor the settlement of three closed landfill cells. A settlement model was developed based on the change in the solid, liquid and gas phases of MSWs due to decomposition. The proposed settlement model was validated with the results from the laboratory and field scale bioreactors and in-situ monitoring data.
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(2022)ThesisTransparency ensures that the decision-making logic used by autonomous agents is available in a form comprehensible to human teammates. It enhances a system's performance, reliability and trustworthiness. Transparency in human-autonomy teaming is a key success factor in the communication between humans and autonomous agents. This thesis focuses on the problem of knowledge transfer between two neural network (NN) agents in a swarm-guidance task in the presence of a human observer. A novel three-module knowledge transfer framework is proposed to interpret non-symbolic knowledge of communicative autonomous agents into a transparent human-friendly form. The knowledge interpretation module transforms the NN into a rule-based knowledge representation. The relevant knowledge is then chosen by a knowledge selection module to transfer it to the other agent. Finally, the knowledge fusion module combines the newly incoming knowledge with the receiver agent's existing knowledge. Two algorithms are introduced to transform NNs into a rule-based knowledge representation. The first algorithm, the Exact-Convertible Decision Tree (EC-DT), rewrites the relationships between nodes and weights of the NN into a multivariate decision tree. The second algorithm, the Extended C-Net, leverages the training data to learn the association between the NN's nodes at the final hidden layer and the outputs and then uses recursive back-projections to derive the rules regulating input-output relationships. Performance is assessed using three measures: fidelity, compactness and transparency. EC-DT has higher fidelity, while Extended C-Net produces more compact rule sets. The fusion module then evaluates the effectiveness of transmitted rule-based knowledge in new environments. The rule-based representation is projected back into forms that can be integrated with the NN representation at the receiver agent's end. A retraining strategy, Priority on Weak State Areas (PoWSA), is introduced to help speed up the learning process in novel scenarios. Analyses of the proposed methodology in a swarm-guidance problem show higher training stability and chances of success in return for a slight increase in computational costs. The framework provides a more transparent knowledge representation that could be visualised to complement the verbal rule-based representation.
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(2022)ThesisMission Planning for a Multi-Uncrewed Ground Vehicle (UGV) is vital for smooth and effective autonomy and coordination. Sub-problems of mission planning are NP-hard and include task allocation, scheduling, and motion planning. Swarm Optimisation Algorithms (SOAs) have attracted increasing attention due to their superiority in addressing NP-hard problems. This thesis contributes a comprehensive evaluation of SOAs, design of new SOAs and their application to the multi-UGV mission planning. The analysis of nineteen SOAs in their organic form and their performance on five sets of benchmark problems motivated the development of a unified taxonomy for swarm optimisation. This systematic approach shed light on new design areas for SOAs, which led to two new variants for continuous Ant Colony Optimisation (ACOR), namely ACOPAR and MACOR respectively. ACOPAR is designed specifically for multi-UGV path planning by 1) designing a probability-based random-walk strategy to balance exploration and exploitation; and 2) proposing an adaptive waypoints-repair method for improving feasibility. Experiments demonstrate the superiority of ACOPAR, especially when addressing high-dimensional problems. MACOR is designed for solving general real-world problems by 1) proposing an adaptive multi-operator framework to select the suitable operator during different evolutionary stages; and 2) presenting four operators for solution construction to improve the search accuracy. Experiments investigate the effects of the different combinations of operators on the algorithmic performance and validate the outstanding search capability of MACOR. A comprehensive multi-UGV mission planning system is then designed. The system integrates environmental modelling, task decomposition and assignment, task sequencing, path planning and trajectory tracking. In this system, 1) a modified cost approximation method is proposed and is integrated with the environmental modelling sub-system; 2) a hybrid clustering method is proposed for task decomposition and assignment; and 3) a three-layer path planner fusing A*, post-processing and MACOR is designed. A benchmark set of multi-UGV mission planning problems is designed for evaluating the performance of planning techniques and experiments to validate the effectiveness of the planning system. ACOPAR demonstrated superior performance in path optimisation and MACOR showed outstanding search capability in general real-world problems and significantly enhanced performance in the three-layer path planner.
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(2022)ThesisProjects account for 20%–40% of all economic activity (Schoper et al., 2018). They are the main vehicle for achieving organizational strategies (Kwak & Anbari, 2009). Despite this, the rates of project success remain low. Many researchers point to project governance as a key factor in improving project success (Crawford et al., 2008). In that light, a key focus in this thesis is the role of project sponsors in project governance, particularly their relationships with project managers and project teams by way of formal and informal governance mechanisms. However, little is understood about the interplay between two major types of governance mechanisms, formal and informal, regarded as either substitutes or complements. This lack of understanding can be attributed to two factors: (1) a lack of a holistic and dynamic perspective in developing project governance mechanisms and (2) little consideration of project sponsors’ cognitive barriers in implementing the governance mechanisms. This thesis draws on Yin-Yang and mindfulness theories to explore whether and how an appropriate balance can be established between complementary yet conflicting project governance mechanisms, with a view to project performance. Three Chinese case studies were conducted to verify the usefulness of Yin-Yang principles in guiding the interplay of formal and informal governance mechanisms and the importance of the project sponsor’s mindfulness in balancing the governance mechanisms. The case studies suggest this approach may enhance the project’s performance.
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(2022)ThesisLight-matter interaction within a strong coupling regime has attracted much attention because of its potential applications in quantum manipulation, Bose−Einstein condensation, optical transistors, coherent emission or absorption, photovoltaics, ultrafast optical switching, sensing, low-threshold lasers, quantum fluid of light and all-optical logic devices. However, conventional materials used in strong coupling suffer from several challenges, as follows: low working temperature, small binding energy, low-quality factor and challenging fabrication. To overcome these limitations, transition metal dichalcogenides (TMDCs) and 2D lead halide perovskite materials are used to achieve a strong coupling regime between optical and polariton modes. This thesis initially reviews previous studies that used TMDCs or perovskite materials in a strong coupling regime. Owing to TMDCs’ optical properties, several studies reported the strong coupling between exciton and optical cavities. However, current structures face many challenges, including difficulties in fabrication and the associated cost increase. The strong coupling between exciton in TMDCs monolayer, plasmonic resonance in silver and anapole mode in Silicon nanodisk was analysed at room temperature and normal incident. This nanostructure provides large Rabi splitting accompanied by a giant field enhancement, thereby paving the way for the creation of exciton-polariton devices. Although previous studies used metallic nanocavities to excite plasmonic resonances that offered a small mode volume and strongly coupled them with exciton in TMDCs, damping losses in metals degraded the performance of exciton-polariton systems. Consequently, researchers used dielectric materials as an alternative to plasmonic materials to observe a strong coupling regime. However, exciton-polariton devices that use dielectric materials suffer from large mode volumes. This thesis explores the strong coupling between hybrid resonance and exciton in hybrid dielectric-metallic nanostructure and TMDC monolayer by using metallic and dielectric materials that include small mode volume low losses. Another material with potential for strong coupling is lead-halide perovskite. Lead halide perovskite materials have a larger binding energy at room temperature compared with conventional materials. Thus, the strong coupling between exciton of perovskite and photonic cavity has been demonstrated in different platforms, such as plasmonic nanocavity and distributed Bragg reflector-based microcavity. The former suffers from large intrinsic loss due to the nature of noble metals, and the latter may involve a complex fabrication process. In recent years, researchers have also used a guided-mode resonance supported by a photonic crystal slab to achieve exciton-polariton in perovskite metasurface. In this thesis, the strong coupling between Mie resonances and exciton is explored at room temperature without resorting to other photonic cavities. Finally, at the end of this thesis, the future perspective and a summary of this research's main results are presented.
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