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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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Item Dynamic mud deposition along the fluvial–tidal transition zone in the Waihou River, Aotearoa New Zealand(Journal Article, American Geophysical Union (AGU), 2025)The fluvial–tidal transition zone (FTT) is a critical interface where complex interactions between river flow, tides, and sedimentation shape geomorphic systems and influence the dynamics of aquatic environments. However, few previous studies have integrated real‐time hydrodynamic data with sedimentary deposits. In particular, the range of depositional conditions over which mud accumulates remains poorly constrained, and little is understood about how these deposits are preserved in the stratigraphic record. To address this knowledge gap, we examined co‐located hydrodynamic instrument data and sedimentary deposits from the lower Waihou River, Aotearoa New Zealand. Results reveal that “dynamic mud” events, including fluid mud and rapidly deposited mud, dominate the spatial and temporal record, with few “static mud” events in which mud is deposited through gravitational settling. We suggest that dynamic mud conditions with the potential for deposition may occur throughout the tidal cycle, although cyclic tidal successions are never fully preserved. Many of the trends in sedimentation observed in studies of larger systems are not present in this small muddy river system, indicating the significance of climatic and river‐flow characteristics on the sedimentary record. This work underscores the importance of studying systems of multiple sizes across diverse climatic regimes to establish holistic facies models to reconstruct geological history accurately.Item Quantitative characterization of the multiscale mechanical properties of low-permeability sandstone roofs of coal seams based on nanoindentation and triaxial tests and its implications for CO2 geological sequestration(Journal Article, Springer, 2025)Microstructural heterogeneity of low-permeability sandstone roofs of deep unmineable coal seams due to diagenesis significantly affects rock mechanical behavior, greatly impacting the sealing potential of in situ CO2 sequestration and the structural stability of the geological formation. However, little is known about how the microstructure of different mineral groups influences the multiscale mechanical behavior of deep sandstone. This study proposes a new method for quantitatively characterizing the multiscale mechanical properties of low-permeability sandstone and shows the mechanisms responsible for mechanical failure at the micro-, meso-, and macroscale. Triaxial compression tests and targeted nanoindentation tests were conducted to assess the micro- and macroscale mechanical properties of different types of sandstone. The micro- and macroscale experiments were coupled with numerical simulations of compression using a unified cohesive model based on Voronoi polygons to clarify the multiscale mechanical behavior. The results indicate that quartz, the primary mineral component of the sandstones examined, exhibits the strongest micromechanical properties, followed by feldspar, calcite, and clay minerals. Compared to polycrystalline quartz, monocrystalline quartz has a more stable microstructure and is mechanically stronger. The macro-mechanical properties of tight sandstone samples are weakened by increased microstructural inhomogeneity and larger grain size. This leads to a higher likelihood of splitting damage, characterized by a high degree of discrete and weak stress sensitivity. The major conclusion is that the positive rhythm lithofacies of medium-grained sandstone to siltstone are the most favorable for efficient CO2 sequestration in deep unmineable coal seams.Publication Axial capacity of face-to-face built-up aluminium alloy columns: Numerical simulation and design proposal(Thesis, The University of Waikato, 2025-03-25)In recent years, aluminum alloy has seen increased use in construction due to its exceptional corrosion resistance and mechanical strength, especially in structural elements like channel sections, hollow pipes, and angles. Cold-formed aluminum alloy face-to-face (CAAFTF) built up channel sections with web holes or without web holes have emerged as a significant development in the construction industry, focusing on streamlining the installation of plumbing and electrical services as well as Glass walls in front of buildings. Previous research indicated that these aluminum alloy sections were studied on bending capacity with web holes and found the bending modified formula for plain webs as well as the web with perforated sections. However, no comprehensive study has been reported in the literature for such aluminum alloy built up face to face columns subjected to compression. This study investigates the axial compression behaviour of aluminium alloy columns with perforated webs, focusing on the influence of screws and perforations on axial capacity. A numerical analysis was conducted on screw-fastened, perforated, face-to-face built-up aluminium alloy channel sections under axial compression. The finite element (FE) model developed using abaqus was validated against 29 experimental results from the literature. The validated nonlinear elasto-plastic FE model was then extended to analyse 495 parametric FE models to examine the effects of key parameters, including modified slenderness, screw number, number of web holes, hole diameter, and section thickness, on the axial strength. The parametric analysis revealed a reduction in axial strength by approximately 8% for every 0.2 increment in the diameter-to-web width ratio (a/h). Axial strength results from experimental tests and FE analysis were compared with current design guidelines in the Australian/New Zealand Standards (AS/NZS 4600). The analysis showed that AS/NZS design strengths were overestimated by 15% for single perforated webs and underestimated strengths by 12% for multiple perforated web sections but AS/NZS estimation for plain section is more closely match with experimental results. A new strength reduction factor equation was developed for aluminium alloy face-to-face built-up channel sections with single and multiple perforated webs. Reliability analysis confirmed the accuracy of the proposed equation, which is applicable within specific limits of slenderness ratio, web width-to-length ratio, and web width-to-thickness ratio. The findings indicate that introducing perforations reduces the axial capacity of plain sections by 8% to 16% for single and multiple perforated webs, respectively. This study provides valuable insights for the design and optimization of aluminium alloy built-up sections with perforated webs.Item Perceptions of warmth and competence conveyed by hard sell and soft sell voices: A cross-cultural study(Journal Article, Taylor and Francis Group, 2025)We assess the reactions of Generation Z consumers to hard and soft sell vocal styles in two countries (France and New Zealand) to understand whether the association of warmth and competence personality traits differs across countries. Results reveal commonalities and differences that advertisers should take into consideration when designing advertising vocal strategies. In both countries, the soft sell vocal style conveyed significantly more warmth than the hard sell style. Our study also reveals differences between countries with French participants having a clear preference for soft sell voices, which they rated very high in both warmth and competence, whereas participants from New Zealand found the hard sell voices significantly more competent than French participants did.Item Words on walls: The linguistic landscape of Kirikiriroa primary school classrooms(Conference Contribution, 2024)Language contact between te reo Māori and English has resulted in one of the central features of New Zealand English (NZE): the integration of loanwords from the Indigenous, donor language, te reo Māori, into a dominant Lingua Franca (Hay et al., 2008). Previous works have analysed the presence and presentation of these loanwords across a number of mediums. Our study, however, examines data directed at a previously unexamined demographic: primary school-aged children. We aim to establish which loanwords children are regularly exposed to, and thus examine a most relevant domain: the classroom. Considering the linguistic landscape of classrooms (schoolscapes) offers insight into the language use that occurs within them. Further, the classroom is educational in the traditional sense, but also in the developmental sense, in the acquisition of broader social meaning. Previous schoolscapes research has highlighted not only their pedagogical importance, but their influence in the construction and transmission of language ideologies (Pzymus and Huddleston 2021; Brown 2012), making these particularly valuable spaces to study. This study presents a schoolscape investigation of nine Waikato classrooms by analysing loanwords arising in educational artefacts directed at primary-aged children (7-11) in an English-medium school setting. We make the following contributions: (1) a systematic schoolscape method for analysing contact-induced language phenomena; (2) quantitative and qualitative analyses of loanwords identified in our data; (3) a detailed taxonomic expansion of te reo Māori loanword categories (semantic and syntactic) in present day NZE. In this talk, we ask the following questions: RQ1) What type of te reo Māori (loan)words are children regularly exposed to through schoolscapes in A/NZ? RQ2) What is their distribution across schools/classrooms/years? We find that, in the classes examined, children encounter both high levels of exposure to te reo Māori (loan)words and high levels of variation in the types of words present. On average, children encounter one te reo Māori token for every ten English tokens. As in previously identified trends (Macalister, 2006b), most loanwords found are nouns belonging to semantic categories pertaining to the environment, place names and social culture items. However, we also identify prominently occurring words and word types that have not previously been identified in corpora. We show that, within classrooms, children regularly encounter a landscape richer in te reo Māori (loan)words than previously seen, but also one characterised by substantial variation.
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