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Privacy leakage quantification in vehicular ad hoc networks
(The University of Waikato, 2026) Daramas, Atthapan; Kumar, Vimal; Barcellos, Marinho
Vehicular Ad hoc Networks (VANETs) offer the benefits of enhancing road safety and efficiency through the frequent information exchange among vehicles through continuous broadcasting of their locations and kinematics. While VANETs can be a potential solution to reduce road accidents, frequently announcing locations raises concerns about user privacy, as vehicles may become targets of trajectory tracking, resulting in the exposure of sensitive locations visited by vehicle users. Several works in the literature have tackled the problem of privacy leakage and privacy preservation through mechanisms that use periodically changing pseudo-identities---known as pseudonyms in VANETs. However, most of this work was done before standards bodies, such as ETSI and SAE, developed VANET communication standards that described how messages should be formed and broadcast, and when pseudonyms should be changed. The use of VANET communication standards makes attempts by the research community to preserve users' privacy outdated and leaves the quantification of privacy leakage in VANETs unaddressed. By keeping communication standards as the context, this thesis aims to fill the gap in understanding potential privacy threats in VANETs and to quantify privacy leakage when these standards are enforced. We analyse potential VANET privacy threats using the LINDDUN framework — a privacy threat elicitation framework and uncover 13 privacy threats in VANET communication, ranging from unawareness of vehicle communication to privacy leakage through user reidentification when the full trajectory is reconstructed. The ability to reidentify a user's true identity from a reconstructed trajectory highlights two sides of the same coin in VANET privacy issues: privacy leakage through communication and the adversary's ability to reconstruct vehicle trajectories. Given the scarcity of real-world datasets, research on VANET privacy quantification can be hindered from being conducted in accordance with communication standardisations. We analyse two real-world VANET communication datasets and identify three limitations in these datasets that render them inadequate for VANET privacy quantification research. Therefore, we develop two VANET communication datasets based on the VANET communication standards from two major standards bodies, ETSI and SAE, to serve as substitutes for inadequate real-world datasets. Based on the findings from our privacy threat elicitation, three vehicle trajectory reconstruction models are developed to simulate privacy attacks against the standardised VANET communication. The three proposed trajectory reconstruction models include a path history-based approach, a Bayesian approach, and a Kalman filter approach. Our trajectory reconstruction models show that 65 to 98% of the trajectory can be fully reconstructed, where the amount of fully reconstructed trajectory depends on the tracking models and the communication standards. Our findings indicate that the VANET communication standards may not sufficiently protect users from privacy threats, as most of the trajectory can be reconstructed by the adversary, and highlight the need for enhanced privacy-preserving mechanisms that can be deployed alongside existing standards.
A preliminary study: Do the topography and frequency of stereotypy predict parent play bid engagement in children at high risk of autism
(The University of Waikato, 2026) Lin, Hung-Chun (Michael); Carnett, Amarie
Autism spectrum disorder (ASD) is a complex neurodevelopmental condition characterised by two core features: communication deficits & social interaction difficulties and restricted and repetitive behaviours, interests, or activities (RRBIs). Although numerous studies have been conducted in the social engagement and communication domain, research on RRBIs and remains relatively limited. This thesis aims to conduct a systematic review on stereotypy, a lower-order RRBI, to evaluate the current state of knowledge in this domain with a focus on assessment and measurement. Following this review, a pilot study using a novel coding system examines stereotypy and response to parent play bids among children at high risk of ASD, using video samples from a larger grant-funded project. Results of our pilot study suggest this assessment tool may be useful for evaluating learning impacts and to help determine if specialised intervention is needed for lower-order RRBIs. Additionally, the limited findings from our sample participants who were assessed with our tool suggest that stereotypy did not hinder children’s responses to parent play bids, thus not needing specialised interventions. Given the limited sample size, findings should be interpreted cautiously. Implications and future research directions are discussed.
Development and validation trace geosmin and 2-MIB detection in seawater: Application to zeolite and photocatalytic treatment in marine RAS water
(The University of Waikato, 2026) Kasseneva, Gulmira; Lay, Mark; Gavin, Chanelle
Taste and odour compounds such as geosmin (GSM) and 2-methylisoborneol (2-MIB) are a major challenge in marine recirculating aquaculture systems (RAS) because they are occur at trace ng/L levels in the water, accumulate in fish flesh and cause strong earthy off-flavours that reduce customer satisfaction and perceived product quality, while remaining difficult to remove and to measure reliably. This thesis addresses a combined analytical and treatment gap by developing and validating a GC-MS method for trace-level GSM and 2-MIB detection in seawater and applying it to evaluate zeolite-based adsorption and photocatalytic treatment options in marine RAS water. A headspace solid-phase microextraction GC-MS (HS-SPME-GC-MS) method was developed, optimized and validated for artificial and real seawater matrices with a target detection limit below 10 ng/L. The final conditions used SIM mode, an internal standard, 3 g NaCl in 10 mL samples, 60°C and 30 min incubation, and 15 min extraction, achieving linear calibration with R² > 0.99 and limits of detection below 10 ng/L for both compounds. Systematic experiments revealed that matrix composition, organic content, competitive sorption on the fibre, incomplete SPME enrichment and analyte instability all significantly affected performance. Using the validated method, batch experiments in artificial seawater at 1000 ng/L compared powder zeolite-Y, an immobilized TiO₂-zeolite coating with and without UV, and UV alone. Powder zeolite-Y achieved rapid and near-complete removal (about 95% for 2-MIB and 99% for GSM, with capacities ~ 7.5 ng/mg), while the TiO₂-zeolite coating with UV initially gave ~97-98% removal but declined on reuse. Overall, the work shows that trace-level GSM and 2-MIB in seawater are challenging to manage because of low concentrations, volatility and SPME limitations, but that a carefully controlled HS-SPME-GC-MS method combined with zeolite-based adsorption provides a practical basis for monitoring and reducing these off-flavour compounds in marine RAS water.
Integration of agricultural systems for environmental sustainability: Vermicomposting organic resources for waste management and food production in a circular economy
(The University of Waikato, 2026) Robertson, Charlotte; Lay, Mark; Gavin, Chanelle; Bertram, Danielle; Quintern, Michael
Food production creates organic waste. Dissolved air flotation (DAF) sludges from meat processing are problematic to dispose of; they are odorous, have high moisture contents and are rich in nutrients. Direct land application without stabilisation of nutrients is common. Paper wastes can often be recycled, but food-contaminated paper wastes are usually landfilled. Nutrients in these two organic resources are therefore usually wasted. This research demonstrated that the compost worm (Eisenia fetida Savigny) could produce vermicompost from novel mixtures of chicken DAF sludge and cardboard, meeting the New Zealand Standards for vermicasts and provided a beneficial effect on plant growth. This research investigated whether commercially produced vermicast applied to onions, potatoes and maize affected yield and/or quality over three consecutive years, with crop rotation on a market garden farm. While international field trials have shown vermicast to improve crop yields, this has not been investigated in rotational crop farming for maize, potatoes and onions. It also has not been conducted in New Zealand at the scale in this thesis. The treatments applied were annual applications of either chicken litter applied at 3 t fresh matter (FM)/ha, vermicast applied at 12.5 t FM/ha or 25 t FM/ha. The treatments were compared to a Control (normal farm management). All treatments, including the Control, received normal fertiliser rates. The trials showed that vermicast applied at 25 t fresh matter (FM)/ha increased onion density and yield (with estimated farmgate profit of >$800/ha), as well as maize grain kernel mass compared to the Control in the third season. This season was the driest, indicating the vermicast provided benefits to crops under abiotic stress. The chicken litter treatment reduced onion density in the second and third seasons. In the third season, this led to an increase in average onion bulb mass, but did not translate to an increase in yield above that of the Control. Additional glasshouse studies were conducted on the application of commercially produced vermicast to determine whether the method or timing of application impacted onion bulbs under glasshouse conditions. Another study investigated the potential for vermicast to supplement diammonium phosphate (DAP) fertiliser in a phosphorus (P) sparing trial in onions on a low Olsen P soil. Final soil Olsen P contents from treatments with 12.5 t FM/ha vermicast and 100% and 75% of recommended P were not significantly different to the Control (100% P and no vermicast). No effect of timing or supplementation of DAP was found on onion size or mass, though these trials were found to be underpowered. The effect of vermicast application timing in relation to crop production has not previously been investigated. Neither has the potential for vermicast to supplement imported phosphate fertiliser on low Olsen P soils. The outcome of this thesis is that beneficial vermicast can be produced from organic wastes and has potential to improve food production in New Zealand. It may also be possible to use vermicast to reduce reliance on conventional fertilisers such as DAP.
Building conceptual understanding: Exploring teachers’ use of virtual manipulatives in primary mathematics education
(The University of Waikato, 2026) Goatley, James; Taylor, Simon
Despite the emphasis on representations and conceptual understanding in the 2024 refresh of the New Zealand Mathematics Curriculum, the integration of virtual manipulatives (VMs) remains limited in classroom practice. Using a mixed-methods action research (MMAR) design, this research investigated how a professional development intervention can shape teachers’ perceptions and integration of VMs into mathematical instruction, following evidence of limited uptake in an initial survey. Quantitative data were collected from 36 New Zealand intermediate school teachers using a modified Constructivist Learning Environment Survey (CLES -VM) to examine teachers’ perceptions and reported use of VMs. This informed a subsequent action research phase with seven participants, incorporating pre- and post- focus groups and a series of professional development sessions following a design-based structure. Qualitative data were analysed using reflective thematic analysis, while survey data were analysed using descriptive statistics. Findings indicated that while teachers initially faced challenges such as the pragmatic constraints of using VMs and the tension between constructivist ideals and classroom management, the professional development intervention helped to mitigate these barriers. The professional development intervention supported teachers to adopt more intentional and flexible approaches to VM use, deepening their understanding of VMs as tools for conceptual development rather than representational extras. An unanticipated finding was the participant-initiated use of generative AI to design custom-built VMs, which contributed to a perceived shift in teacher autonomy. By transitioning from consumers of generic digital tools to creators of tailored resources, teachers were able to address the specific needs of students more effectively. Additionally, participants identified the role of VMs in reducing cognitive load and supporting instructional equity and accessibility. The research suggests that sustainable digital integration requires a hybrid professional development model that balances the immediate need for ready to use resources with the long-term, design-based development of teachers TPACK (Technological Pedagogical Content Knowledge).