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Research Commons is the University of Waikato's open access research repository, housing research publications and theses produced by the University's staff and students.
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Publication Stemming the colonial environmental tide – Ecosystem-based management and shared Crown-Māori co-governance for sustaining our marine coastal estate in Aotearoa New Zealand – Summary report(Report, e Mata Hautū Taketake – the Māori and Indigenous Governance Centre, University of Waikato, 2023-12)This summary report was prepared by Dr Robert Joseph from Te Mata Hautū Taketake – the Māori and Indigenous Governance Centre, Te Piringa Faculty of Law at the University of Waikato for the National Science Challenge Sustainable Seas Ko Ngā Moana Whakauka Project.Item Thermoplastic composites in sustainable construction: Topology optimisation and additive manufacturing for a recyclable and modular building system(Conference Contribution, Association for Computer-Aided Architectural Design Research in Asia (CAADRIA), 2025)Despite the significant environmental impact of the building sector, sustainable building practices are yet to be widely adopted. This paper describes a practical approach based on computational design and additive manufacturing (AM) to generate modular and structural walls, following design for disassembly and recyclability principles. In this research, the anisotropy of recyclable short-fibre reinforced thermoplastic (SFRTP) composites is utilised. The proposed methodology involves starting from the building’s typology and using topology optimisation (TO) as a form-finding tool in the design of structural wall modules. The finite element analyses (FEA) guiding the TO are based on conventional building-codes used for load calculations. The TO-defined modules are then further optimised in stiffness by matching the principal stress directions with the AM printing path. Two case studies, the ground floor of a 3-storey building and a bus shelter, are used to illustrate the outcome of the approach. This comprehensive workflow generates structural elements with built-in optimised and tailored performance while enabling unique geometries that combine structural efficiency with architectural creativity.Publication Development of a real-time technique for in-sditu measurement of pH in capacitive deionisation(Thesis, The University of Waikato, 2025)Capacitive Deionisation (CDI) as a desalination technique proves to be one of the most promising technologies owing to its simplicity and ease of manufacturability. The longevity of CDI depends on a number of factors, such as the ability of carbon to withstand Faradaic reactions to CO2. Furthermore, like other technologies such as (reverse osmosis) RO and (electrodialysis reversal) EDR, scale formation is known to affect its hydraulic efficiency. The slow mineral deposition of magnesium and calcium carbonate is responsible for such phenomena. The extent of the problem is one where the hydraulic efficiency of the device drops well below 10%, a state where the device is considered to be at the end-of-life as it is too difficult to pump water through it. In the preliminary study we examined the performance of an industrial scale (membrane capacitive deionisation) MCDI module that has been in operation intermittently for 5 years to establish familiarity with the performance of a used module. In the main study, we described a new technique for observing the chemical state within the spacer channel of a CDI cell, the part of the electrode that is prone to blockage. This new technique for the direct measurement of pH is based on colourimetric analysis of a novel synthetic formulation of a pH-sensitive dye dissolved in the electrolyte phase. The basis for this novel technique combined a simple optical microscope integrated with a microfluidic device. This microfluidic device containing a microreactor cell of 750 picolitres in size was fabricated to host the electrochemical reaction (electrode and electrolyte phases) demonstrated in this study that recreates the “CDI effect” of an industrial cell. The pH indicator formulations were synthesised from a 1:1:2 ratio of phenolphthalein, bromothymol blue and methyl red in an ethanol solution. The pH indicator, which we denote as the standard formulation (SF), had a density of 0.93 kg/L and pH of 2.74. This was the formulation that was subsequently used in the main part of the study. The dye was characterised by visible range spectroscopy and subsequent conversion to (hue saturation value) HSV colourmap coordinates using the 1976 CIE (International Commission on Illumination) chromaticity model. This enabled the development of a range of pH-Hue relationships using best approximated by sigmoid functions. In the analysis of these functions, we investigated the sensitivity of the pH-Hue relationship to variation in the SF formulation due to selective electrosorption of the dye. It was shown that the variation in functions produced was not significant and that the general pH-Hue relationship did not break down into a non-usable form. Application of the novel technique was initially performed on a membraneless cell configuration. The pH profile was investigated from a starting range of interest of pH 8 to 9 where scale formation occurs. In the second series of reactions, we demonstrated microreactor CDI configurations with varying degrees of membrane coverage from 12.5% to 100%. It was found that the pH variation in the spacer channel was minimal or non-existent across the full charge cycle from adsorption through to desorption. This indicates that obscuration of the carbon surface blocks the protons diffusing from the surface of the carbon where it is generated by way of the standard faradaic reaction in CDI or blocking co-ions from being expelled from the membrane that may result in speciation that affects the pH. We recommend longer in-situ observation type studies be performed to confirm the speciation chemistry present in the spacer channel typical of many situations where electrodes are reducing in performance by way of fouling and scale formation.Publication Walking into the past to explore the future: Utulizing larval densities to measure the effects of two climate change factors, temperature and salinity on Poorohe (common smelt, Retropinna retropinna) abundance in Te Puuaha o Waikato(Thesis, The University of Waikato, 2024-11-23)Poorohe (common smelt, Retropinna retropinna) are a highly valued kai species in Te Puuaha o Waikato (the lower 66 km of the Waikato River). Fisher whaanau have observed changes in the amount Poorohe that are harvested during annual fish harvests. Since Poorohe are particularly vulnerable to environmental changes, whaanau are particularly concerned about the how climate change might impact Poorohe populations. Climate change vulnerability assessments (CCVA) currently exist for several native New Zealand fish freshwater species; however, one does not yet exist for Poorohe. Previous larval distribution studies in the lower Waikato River only sampled as far downstream as Tuakau bridge (approximately 45km from the river mouth). These studies indicated that important spawning habitats likely existed downstream of Tuakau bridge. Temperature increases and saltwater intrusion have been identified as two climate change factors that will likely impact Poorohe in Te Puuaha o Waikato, because ambient temperatures have increased since the industrial revolution and the proximity of the study area to the ocean. A literature review was used to explore the experiences of fisher whaanau through the past, present and how the experiences will continue to change in a changing climate. The effects of temperature and saltwater intrusion on Poorohe populations were explored through replicating the methods of past research carried out in the 1980s and 2010s. Current river temperatures are in the optimal temperature range (12°C - 18°C) for Poorohe spawning. The saltwater wedge was suppressed by the high river flow during the eight-week sampling period, and it is unclear whether saltwater intrusion has an impact on Poorohe spawning. Larval densities did not significantly increase down river, which suggests large spawning habitat is not found downstream of Tuakau bridge. Furthermore, there were no decreases in larval densities in the two saltwater sites. This study has contributed to the available literature necessary to develop a CCVA for Poorohe and explored the cultural heritage of traditionally significant practices in Te Puuaha o Waikato relating to Poorohe.Publication A Foucauldian discourse analysis of judiciary talk about psychopathy(Thesis, The University of Waikato, 2025)Psychopathy-focused literature has primarily been situated in the positivist school of thought, aiming to understand this concept through cognitive, biological, neurological, and behavioural perspectives. Much of this research has been carried out in prisons, conflating the relationship between psychopathy and criminality. The findings from this knowledge base have contributed to the development of different practices and legislation in judicial settings. Some of the consequences of these practices, such as diagnosing psychopathy in the courtroom, have led to harsher sentencing outcomes at the expense of rehabilitation and treatment options. This is despite the lack of consensus as to the definition, cause, and treatment of psychopathy. Traditional research methods have largely overlooked how sociopolitical and cultural contexts have contributed to how psychopathy is understood and responded to. No research exists that sets out to examine how psychopathy is discursively constructed in courtrooms internationally, including in Aotearoa, New Zealand. Therefore, this thesis adopts a Foucauldian discourse analysis approach to uncover the discursive structures that contribute to the construction of psychopathy in Aotearoa New Zealand courtrooms. Four key discourses were uncovered: ‘the psychopath’ as a moral failure, psychopathy and risk, psychopathy and pathology, and ‘the psychopath’ as untreatable. The findings highlighted how psychopathy as a construct has evolved over time in the courtroom. The findings uncovered how shifts in discourses, discipline-specific practices, and technological knowledge have implications for how psychopathy is provided meaning and managed in judicial settings. Through the available discursive frameworks, truths about psychopathic individuals as deviant outsiders who posed a risk to the broader population were constructed. These truths often led to their incarceration and further exposure to practices such as assessment, diagnosis, monitoring and treatment. Through this process, the experiences and authority of those individuals labelled as psychopathic were marginalised.
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