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Effect of foam density on the imperfection sensitivity of aluminium foam sandwich panels under in-plane compression
(The University of Waikato, 2026) Mohan, Devika; Fang, Zhiyuan (Arthur)
Aluminium foam sandwich panels are attractive lightweight structural components because they offer a good combination of low mass, stiffness, strength, and energy absorption. However, their in-plane compressive behaviour is still not fully understood, especially when the foam relative density and out-of-plane geometric imperfections are considered together. This study investigates how variations in the combinations of foam relative density and out-of-plane geometric imperfections influence the in-plane compressive response of these panels, with emphasis on strength, collapse mode, and post-buckling behaviour. These findings improve the understanding of the compressive performance and support more reliable use of these panels in lightweight structural applications. Parametric studies were conducted to examine the in-plane compressive response of 200 aluminium foam sandwich panels with varying relative density and initial imperfection. For certain combinations, mode interaction was enhanced, producing a temporary increase in load carrying capacity. The resulting imperfection-dependent interaction windows do not vary monotonically with either parameter but instead reflect a balance between foam-core stiffness, and imperfection sensitivity. A sensitivity study also showed that plate modulus also has a role in the formation and extend of such mode interaction windows. To support design decisions, a multi-objective performance framework was developed using imperfection tolerance, deformation mode stability, energy absorption, and mass efficiency. In addition, as a practical aid to similar panel configurations, a FE based predictive equation was developed to predict the normalized peak load in the higher imperfection regime.
Volcanic geology and geomorphology of the kaimai rhyolite dome complex, Tauranga volcanic centre, New Zealand
(The University of Waikato, 2026) Clark, Morgan; Pittari, Adrian
The Kaimai Rhyolite Dome Complex (KRDC) is an extinct rhyolite dome complex on the Waikato-Bay of Plenty border which forms a prominent feature at the southern end of the Kaimai Range. Published ⁴⁰Ar/³⁹Ar and U-Pb zircon ages place dome emplacement between approximately 2.87 and 2.2 Ma, placing the KRDC within the Tauranga Volcanic Centre (TgVC) spatially, temporally, and within the transitionary phase of subduction-related volcanism within the North Island from the Coromandel Volcanic Zone to the Taupo Volcanic Zone. It is contemporaneous with the Alexandra Volcanic Group and Okete Volcanics of the western North Island, the wider Minden Rhyolite Subgroup of the TgVC, and predates the ~2.1 Ma Waiteariki Supereruption of the Omanawa Caldera. Despite its prominence on the Tauranga skyline and regional significance the KRDC has never been the primary subject of a dedicated study. This study applies modern volcanological techniques to define the complex and its place within the TgVC, incorporating field mapping, LiDAR-derived geomorphological analysis, petrography, SEM-EDS, XRD, whole-rock major and trace element geochemical analysis (XRF and LA-ICP-MS), and zircon saturation thermometry. The KRDC is recognised in this study for the first time and its six discrete dome centres, Te Weraiti, Kaimai, Kakahu, Hiwiroa, the Eastern Dome, and the Southeastern Dome, all previously mapped as Minden Rhyolite Group on Rotorua QMAP with undefined internal unit contacts and margins. Hiwiroa, the Eastern Dome, and the Southeastern Dome are recognised for the first time on the basis of geomorphology and morphometric analysis. The complex forms a coalesced composite dome ridge spanning 25.8 km along a N-S corridor with a total post erosional volume of 5.67 km3. Field and geomorphological evidence confirm that dome emplacement predates the Waiteariki supereruption. A three-tier framework was developed describing the structural control on emplacement of the dome centres derived from elongation ratios and spatial context, fault-controlled fissure emplacement (Te Weraiti, Kakahu; ER 2.81–3.16), intermediate point-source emplacement within a fault corridor (Kaimai; ER 1.44), and minimal direct fault control (Hiwiroa, Eastern, Southeastern; ER 1.47–1.85). The bimodal distribution of elongation ratios indicating two distinct emplacement modes of both fissure derived and point source rather than a continuous spectrum. Phenocryst assemblages at Te Weraiti and Kaimai are plagioclase + quartz ± biotite ± sanidine ± pyroxene. The KRDC lavas are hornblende absent distinguishing it from the hornblende bearing Waiteariki Ignimbrite. Devitrification groundmass textures are pervasive across all KRDC lavas displaying large spherulites of cristobalite + sanidine, an assemblage consistent across CVZ–TgVC Minden Rhyolites from ~7.8 Ma (Hahei) to ~2.2 Ma (KRDC). KRDC lavas are high-silica 74–78 wt.% SiO₂ high-K calc-alkaline to shoshonitic, peraluminous rhyolites that underwent plagioclase-dominated fractionation. Single-stage fractional crystallisation modelling could not produce these lavas from either Waiteariki Ignimbrite or the potential parental basaltic-andesite basement, requiring assimilation-fractional crystallisation. Zircon saturation thermometry produces mean KRDC melt temperatures ~40 °C cooler than the comparable Mount Misery rhyolite series within the TgVC, indicating the KRDC lavas represent a cooler, more evolved magma batch through a similar petrogenetic process but from a separate plumbing system.
Towards formalisation of 3D user interaction: Making spatial interaction verifiable
(ACM, 2025) Turner, Jessica; Weyers, Benjamin
Interactive systems which incorporate 3D interaction techniques, such as virtual or augmented reality, lack appropriate methods for formalisation to verify and validate their properties. In safety-critical contexts, such as virtual environments used for training users in medical settings, ensuring systems behave as expected is crucial to enabling positive user experiences. In this paper we propose a formalisation that will allow us to express 3D virtual environments, end users and their interactions. This work represents a first step towards creating formalisation methods for virtual reality applications, enabling model checking techniques to ensure systems behave as expected, leading to improved reliability, safety and better user experience in virtual environments.
The appearance of free will in artificial intelligence: How human decision-making is influenced
(The University of Waikato, 2026) Stewart, Annabelle; Perszyk, Ken; Agar, Nick
This thesis examines how artificial intelligence (AI), in particular large language models (LLMs), influences human deliberation and the experience of free will (FW). While much of the existing literature focuses on whether AI systems genuinely possess FW or consciousness, this thesis shifts the focus to how the appearance of these affects human decision-making. It is argued that LLM AI systems show an appearance of FW (AFW) and an appearance of consciousness (AC) through observable behaviours. This appearance is enough to influence human deliberation, even when users may not believe that AI systems have genuine FW or consciousness. While AI systems do not remove alternative possibilities (APs) or take away human control, they do reshape how options are perceived and evaluated, which narrows the phenomenological experience of freedom. This influence often operates below conscious awareness, affecting reasoning processes without coercion. Traditional views of FW and moral responsibility that focus on the ability to do otherwise do not adequately account for external influence on deliberation from AI systems. The thesis concludes that responsibility and accountability should remain with humans, as AI systems function as a tool rather than morally responsible entity. However, the increasing use of AI in everyday decision-making suggests the need to reconsider how influence, human cognition, responsibility, and accountability interact in an AI-mediated environment.
Navigating researcher positionality in comparative and international education research: Perspectives from emerging researchers
(University of Sydney, 2022-11-17) Chin, Mellisa; Beckwith, Victoria; Levy, Ben; Gulati, Swati ; Macam, Alea Ann F.; Saxena, Tanya; Suwarningsih, Dwi Purwestri Sri
Articulating one’s positionality as a researcher is crucial to social research. This is particularly important in comparative and international education research where context, culture and notions of power underpin much of the work. However, researcher positionality has multiple meanings, making it challenging for emerging researchers to navigate its muddied, cluttered and unfamiliar terrain. In this article, seven emerging researchers examine their own researcher positionality within the context of their postgraduate research. Through a series of short vignettes, they draw attention to the different conceptualisations of researcher positionality and uncover the challenges and dilemmas.