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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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Recent Submissions

Effects of different triggering mechanisms on pulse shaping of a TMS pulse generator based on supercapacitor energy storage
(IEEE, 2025) Raju, Soniya; Kularatna, Nihal; Wilson, Marcus T.; Steyn-Ross, D. Alistair
High-voltage pulse generators are useful in many applications such as transient surge simulators, electric fence energizers, and transcranial magnetic stimulation (TMS) systems. Traditionally they are based on a high-voltage DC power supply with or without voltage multipliers for raising the voltage to several thousand volts. In contrast to these complex and costly approaches, we use a pre-charged supercapacitor followed by a step-up transformer and associated output circuitry to develop an inexpensive and flexible high-voltage pulse generator for applications in transcranial magnetic stimulation. Our new approach is to use the high-power delivery capability of commercial supercapacitors. In this work, we explore the advantages of different waveforms applied to the MOSFET associated with the secondary stage of the circuit topology and how they affect the final pulse shape.
Identifying biological fluids using hyperspectral near-infrared imaging and machine learning for forensics analysis
(IEEE, 2025) Faisal, Shah; Ooi, Melanie Po-Leen; Kuang, Ye Chow; Thawdar, Yaminn; Abeysekera, Sanush K.; Reutemann, Peter; Fletcher, Dale; Fleming, Rachel; McClelland, Heather
Near-infrared hyperspectral imaging captures subtle spatial and spectral characteristics of biological fluids on fabrics for forensics analysis. It is a non-destructive approach that could potentially be used for onsite crime scene investigations. However, current data processing methods lack the accuracy and sensitivity required for real-world applications. This paper utilised a 900-1700nm hyperspectral camera to capture blood, semen, and urine fluids that were systematically applied onto a patterned rayon fabric. Multi-Later Perception (MLP) and 1D Convolutional Neural Network (1D-CNN) classifiers were then trained to identify them. A dual evaluation approach, combining machine learning model evaluation metrics (F1-score and accuracy) with uncertainty quantification (Entropy-based and Modal Predictionbased) was then used to assess the performance of the classifiers. The results indicated that the MLP slightly outperformed the 1DCNN for fluid-specific classification tasks, achieving slightly better accuracy and F1-score and lower uncertainty in predictions.
Supercapacitor based TMS pulse generator design - Experimental results versus Matlab MOSFET simulation model
(IEEE, 2025) Raju, Soniya; Kularatna, Nihal; Wilson, Marcus T.; Steyn-Ross, D. Alistair
Supercapacitors are ideal for short-term energy storage due to their high instantaneous power capability. Unlike traditional high-voltage DC power supplies typically used in transcranial magnetic stimulation (TMS) applications, a precharged supercapacitor module can serve as a cost-effective alternative for building a pulse generator with adjustable waveform capabilities. This approach utilizes a supercapacitor module with a capacitor bank rated at a few hundred farads and 10 V, combined with a step-up transformer-based converter and medium-voltage MOSFETs to meet TMS requirements. The output of this pulse generator, including the effects of varying gate voltages, can be accurately predicted using a robust model. This paper presents the design of a MOSFET model, incorporating a newly derived equation that effectively captures the subthreshold, near-threshold, and above-threshold regions of the MOSFET operation. Experimental results are provided and compared with Matlab model simulations, demonstrating the model's accuracy and effectiveness.
Research reciprocity and the ABC's of ABS
(Te Kotahi Research Institute, University of Waikato, 2026) Hudson, Maui; Hutchins, Leke
Attribution, Benefit Sharing, and Capacity Building across the research lifecycle. What is Research Reciprocity? It represents a deep commitment to partnership with communities in research collaborations. It emphasizes the need for both benefit sharing and power sharing in the data life cycle. What is ABS? Access and Benefit Sharing governs how genetic resources and associated traditional knowledge are accessed, and how benefits from their use are shared fairly and equitably. Why it matters: Research and commercialization have often separated biodiversity and knowledge from the peoples who sustain them. ABS addresses unequal returns.
Access and benefit sharing considerations for ancient eDNA and crop genomes
(Te Kotahi Research Institute, University of Waikato, 2026-10-28) Hutchins, Leke
Ancient environmental DNA and crop genomics can reconstruct past environments, trace crop histories, and recover genetic variation relevant to contemporary environmental and agricultural challenges. These possibilities also raise questions about who may authorize access, whose histories and stewardship are represented in genomic data, and how benefits should be shared. This report examines those questions through access and benefit sharing (ABS), Indigenous Data Sovereignty, and Indigenous data governance. The central argument is that responsible research requires governance throughout the full research lifecycle. Initial access agreements and eventual benefit sharing leave a “missing middle” in which samples become sequence data, analyses produce interpretations, and outputs enter repositories, breeding programmes, or commercial applications. Consent, mutually agreed terms, provenance, data governance, attribution, and accountability must remain active through these stages and into subsequent reuse. Neither the age of a sample nor its environmental character removes its relationships to living peoples. Soil, water, permafrost, archaeological materials, and historical specimens may remain connected to Indigenous territories, ancestors, cultural practices, and continuing systems of responsibility. Human genetic bycatch creates additional concerns about privacy and consent. Describing materials as ancient should therefore prompt attention to their histories and relationships rather than presume that they are culturally unclaimed. The discussion of kalo demonstrates why globally circulating crops can retain specific genealogical and cultural significance. A layered approach to benefit sharing distinguishes direct responsibilities to project partners, enduring responsibilities to wider communities of stewardship, and broader responsibilities when genomic value circulates through international research and commercial systems. These layers also inform research on barley, rice, and wheat, whose useful diversity reflects long histories of cultivation, exchange, and farmer innovation. For ancient eDNA and crop genome research, the practical task is to establish continuing community authority, clear conditions for materials and data, and benefits defined with the people whose lands, knowledge, and stewardship make the work possible. Genomic interventions should be assessed in relation to equitable governance, farmer and community autonomy, ecological responsibility, and the restoration of relationships disrupted by extractive research and industrial agriculture.