Tuwhera Research Repository

The Tuwhera Research Repository provides sustainable open access and archiving to a broad range of AUT produced research - theses, research outputs and datasets.

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Recent Submissions

Access status: Open Access ,
From Compliant to Critical: Forecasting Emerging E. coli Risk in New Zealand’s South Island Rivers
(MDPI AG, 2026-09-12) Tiwari, Parul; Goyal, Tanishqa; Kulasiri, Don
Freshwater quality is degrading globally, and regulatory monitoring remains largely retrospective, identifying non-compliance only after it occurs. This study identifies whether multi-year, regulatorily relevant compliance breaches can be forecast from sparse monthly monitoring records alone and whether such forecasts improve on the assumption that next year resembles the current one. Using approximately two decades (2004–2024) of Land, Air, Water Aotearoa (LAWA) data from 497 South Island, New Zealand river sites, a single pooled gradient-boosted (LightGBM) classifier was trained to forecast Escherichia coli worst-band (Band E) non-compliance under the National Policy Statement for Freshwater Management at one-, two-, and three-year horizons, benchmarked against persistence, trend projection, and majority-class baselines under strictly temporal validation. The model discriminated breaches reliably (AUC 0.84–0.85) and exceeded persistence in balanced accuracy at all three horizons, significantly at two and three years. Its principal value was early warning: among currently compliant sites, it recovered roughly half of subsequent breaches, transitions that persistence cannot detect by construction, yielding a forward watchlist of 97 sites at risk of entering the worst band (Band E) by 2027, concentrated in pastoral catchments. Forecasting from monitoring data alone imposes an honest ceiling; scores are reported as risk rankings. The findings support a shift from reactive to anticipatory freshwater management.
Access status: Open Access ,
Insights Into the Pulsar Timing Array Hypothesis Space
(American Physical Society (APS), 2026-09-28) Zahraoui, El Mehdi; Maturana-Russel, Patricio; Van Straten, Willem; Meyer, Renate; Gulyaev, Sergei
We present novel insights into the pulsar-noise model space in pulsar timing array (PTA) experiments. Through a comparative analysis of the same Parkes PTA second data release observations processed with the 2020 and 2023 pipelines, we show that data processing materially changes the distribution of posterior support across competing noise hypotheses and increases sensitivity to weak contributions such as the solar wind. A solar-wind component appears in the highest-posterior hypothesis for ten pulsars under the 2023 pipeline, against four under the 2020 pipeline, while the corresponding mean electron density estimates are consistent with Parkes PTA DR3 results. Furthermore, hypothesis-space analysis exposes model competition and degeneracies that are hidden by single-model summaries. Approximately 75% of the pulsars retain substantial posterior support for alternative noise descriptions. Therefore, understanding the nature of the pulsar-noise hypothesis space is crucial for robust inference and nanohertz gravitational-wave background searches.
Access status: Open Access ,
Multi-Level Inclusion Systems: How Tempered Radicals Influence Change in Manufacturing Organisations
(Taylor and Francis Group, 2026-10-05) Griffiths, Chris; McGhee, Peter; Smollan, Roy
This study explores how tempered radicals promote inclusive workplaces across organizational levels in manufacturing companies. Tempered radicals work within established structures to deliver socially inspired change, strategically challenging norms while balancing organizational commitment and personal values. Building on Meyerson’sfoundational work, this research extends tempered radical theory by developing a Multi-Level Tempered Radical Approach Framework that examines how these change agents operate differently across frontline, supervisory, and managerial levels. Within manufacturing settings, 27 participants were interviewed through narrative inquiry methodology. We employed Leximancer text mining and thematic analysis. The findings reveal distinct patterns in how tempered radicals construct identities, navigate work environments, employ operational methods, and engage in interpersonal interactions at each organizational level. The framework developed for this study contributes to tempered radical literature by providing empirical evidence of level-specific strategies within hierarchical manufacturing contexts—an underexplored setting in existing research. The study advances understanding of Meyerson’s spectrum while offering insights for enhancing workplace inclusion in traditionally hierarchical industries.
Access status: Open Access ,
Do Investors Value Environmental Corporate Policies? Evidence From the Australian Market
(MDPI AG, 2021-03-16) Chandra, Mohinesh; Tourani-Rad, Alireza
In this paper, we explore the relationship between a firm’s environmental policies and their risk-adjusted stock returns, using a sample of stock exchange-listed Australian firms over the period of 2010–2018. We observed a positive and statistically significant relationship suggesting that a firm’s environmental policies partially explain their stock performance. Moreover, we found that investors in the Australian market significantly value a companies’ efforts to reduce emissions, and that this primarily drives the investors’ observed reaction to a firm’s social corporate policies. Next, we formed portfolios and observed that portfolios formed on high environmental, social, and governance (ESG) Environmental Pillar scores consistently outperformed those formed on low-ESG Environmental Pillar scores. Overall, our results lend support to the notion that investors in the Australian market value information about a firm’s social policies.
Access status: Open Access ,
24 GHz Flexible Antenna for Doppler Radar-Based Human Vital Signs Monitoring
(MDPI AG, 2021-05-27) Kathuria, Nitin; Seet, Boon-Chong
Noncontact monitoring of human vital signs has been an emerging research topic in recent years. A key approach to this monitoring is the use of the Doppler radar concept which enables real-time vital signs detection, resulting in a new class of radar system known as bio-radar. The antennas are a key component of any bio-radar module and their designs should meet the common requirements of bio-radar applications such as high radiation directivity and mechanical flexibility. This paper presents the design of a four-element antenna array on a flexible liquid crystal polymer (LCP) substrate of 100 μm thickness and εr of 3.35. The designed antenna array can be used with a 24 GHz bio-radar for vital signs monitoring in a non-contact manner. It features a relatively compact size of 36.5 × 53 mm2 and measured gain of 5.81 dBi. The two vital signs: breathing rate (BR) and heart rate (HR) of two human subjects are detected with relatively good accuracy using the fabricated antenna array and radio frequency (RF) output power of −3 dBm from a distance of approximately 60 cm. The effect of bending on the antenna performance is also analyzed.