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On the processing of a powder metallurgy low-cost Ti alloy via different induction sintering strategies
(MDPI, 2026) Bolzoni, Leandro; Roduit, Valentin; Carreno-Morelli, Efrain; Yang, Fei; Raynova, Stiliana (Stella) Rousseva
Reducing the cost of Ti alloys, both from a processing and compositional point of view, is a pathway forward for harnessing more extensively the industrial and environmental benefits associated with their uses, and it is an outstanding manufacturing challenge. Thus, this study investigated the manufacturing of a low-cost Ti alloy using different induction sintering strategies where both aspects are designed to reduce the final cost. The primary conclusion is that induction sintering of Ti alloys by cycling the temperature above and below the allotropic phase transformation (i.e., beta transus) suffices for the need for high green density values, which are commonly achieved using more expensive methods. This is due to faster densification kinetics. The fast uniform heating of the alloys leads to homogenous pore distribution in the entire volume and the dissolution of the alloying elements, especially during cycling sintering due to the fine particle size of the alloying elements. Consequently, despite the low homologous sintering temperatures used, the induction sintered low-cost Ti alloys do not fail catastrophically, although the ability to sustain plastic deformation is affected by the features of the residual porosity.
Supercapacitor assisted multilevel inverter topology for off-grid renewable energy systems
(IEEE, 2024) Naligama, Chamila Anuradha; Kularatna, Nihal; Steyn-Ross, D. Alistair; Gunawardane, Kosala
Supercapacitor assisted (SCA) techniques are a new family of power electronic building blocks for renewable energy systems based on the theory published as SCA-loss management (SCALoM) concept. SCA inverter is a unique application of SCALoM theory, capable of meeting any capacity of off-grid inverter requirement, based on a combination of an even number of smaller inverters with suitably sized supercapacitor banks. SCA-inverter technique reduces input loop losses and transistor voltage stresses while providing DC-UPS capability without using batteries. This paper discusses the technical background of the SCA-inverter arrangement of operating seamlessly without common load balancing issues observed in other multi-inverter systems and techniques. The experiment results of two/four-SCA-inverter arrangement show stable operation of the inverter systems, both in switching transients of the supercapacitor banks and steady state operation. Four-SCA-inverter arrangement shows up to 2.5% efficiency improvement by equally partitioning the load into four inverters with no load balancing issues. As the four supercapacitor modules are switched at millihertz order frequency, it eliminaties the need for any EMC filters and dynamic losses in the frontend SCA arrangement are negligible.
Implementation of a supercapacitor assisted inverter system for reducing input loop losses: Preliminary results of a four-stage inverter
(IEEE, 2024) Naligama, Chamila Anuradha; Kularatna, Nihal; Steyn-Ross, D. Alistair; Gunawardane, Kosala
Supercapacitor assisted loss management (SCALoM) concept has laid the theoretical foundation to develop high efficiency power converters for renewable energy systems using supercapacitors as lossless voltage droppers and energy buffers. SCALoM theory is applicable to inverter combinations in reducing overall losses, mainly occurring in the input loop, including losses in the DC bus capacitor. Supercapacitor assisted (SCA) multi-inverter technique reduces the voltage stress on the internal components of inverters enabling the use of more efficient lower voltage rated components. A summary of the theoretical foundations with reference to previous works on the topic is presented first. The four-SCA-inverter technique discussed in this paper extends the input voltage range of an inverter system by two times and reduces the input loop current by two times. The preliminary results obtained from the first experimental prototype of the 700W four-SCA-inverter system coupled with four identical 250F supercapacitor modules switched at low frequencies (less than 0.02 Hz), show up to 2.53% of efficiency gain at the inverter end. Additionally, proposed technique provides unquantified efficiency gains by reducing the ripple currents in the system, functioning as an energy buffer. Development of a high power capable SCA-inverter prototype is in progress.
Redesigning files to embed concise provenance metadata
(The University of Waikato, 2026) Phua, Thye Way; Kumar, Vimal; Bainbridge, David
Data provenance is essential for validating the origin, history, and trustworthiness of information. However, despite extensive research, provenance systems have seen limited mainstream adoption. This thesis argues that this gap stems from two fundamental deficiencies: (i) the lack of temporal awareness in existing models and (ii) the detachment of provenance metadata from the primary data. Current systems often treat versioning as symbolic markers rather than capturing the content of change, and they store metadata in centralised repositories that are prone to desynchronisation. To address these challenges, this research proposes a framework that integrates temporal data evolution with embedded provenance. The thesis posits that provenance must be integral to the data artefact itself to ensure portability and integrity. A prototype system was developed using a FUSE-based filesystem, employing delta encoding to capture fine-grained changes and a custom block-based format to embed provenance metadata and version histories directly within files. This architecture ensures that lineage information remains inseparable from the data it describes. The system was evaluated through microbenchmarks and a macrobenchmark involving a full Linux kernel compilation. The evaluation confirms that the delta-based storage model is efficient, achieving a sixty-fold reduction in space compared to full snapshot retention. Historical state reconstruction incurs linear overhead relative to version depth, remaining manageable for typical file lifespans. Although the prototype introduces a performance overhead of approximately 7.4% during intensive workloads, it successfully validates the feasibility of the approach. The findings demonstrate that integrating temporal awareness with embedded metadata significantly improves the accuracy and completeness of provenance tracking, offering a robust foundation for accountability in dynamic environments.
He kai kei aku ringā (there is food at the end of my hands): Developmental transdisciplinary research to inform co-management of Tuangi in Ōhiwa Harbour
(The University of Waikato, 2026-10-21) Reihana, Kiri; Paul-Burke, Kura; Ellis, Joanne I.; Bulmer, Richard H.; McGowan, Pā (Robert)
Indigenous Knowledges, traditions, practices and ways of being are increasingly present within the global marine conservation discourse. As long-standing intergenerational custodians of a large percentage of the earth’s natural areas, many Indigenous communities seek to play a central role in co-defining the issues, co-participating in the process and co-designing the solutions for their lands and water resources. The value and benefits of Indigenous-led conservation, knowledge creation and participation are exponentially expanding within scholarship. This research is located within Ōhiwa Harbour, an estuarine inlet in the Bay of Plenty, in the North Island of Aotearoa New Zealand. The thesis explores historical and contemporary information of the identified taonga (sacred, treasured) species tuangi, or cockles, within Ōhiwa Harbour. The research was designed to identify relevant tools and technology to address the declines of the tuangi populations, and to assist iwi (tribes) and authorities in providing information for decision making over the shellfish beds. Finally, findings of the thesis produced species distribution models which assisted in understanding tuangi-preferential habitats within the estuary, and the development of rapid site-assessment techniques based on mātauranga Māori (Cultural knowledge system). This thesis uses a transdisciplinary mixed method approach inclusive of mātauranga Māori, marine sciences, and technology. This research is led by kaupapa Māori (a Māori way of being, seeing, and doing) informing and developing a Tīwaiwaka framework informed by multiple evidence-based approaches as a means of weaving multiple knowledge systems. To achieve this, the guiding framework and methodology emerged from the te ao Māori conservation movement Tīwaiwaka, which prioritises kaitiakitanga (active stewardship), unification and reciprocating co-existence with our natural environment. Results from the legislative review on marine governance highlighted historical colonial exclusionary policies, accelerated extractive practices and tools displacing Māori people and culture on the settlement of Aotearoa. The polarity of views from the two cultures set the backdrop of the ensuing misunderstandings over management and governance of the marine space, and all natural resources, within Aotearoa. Therefore, future aspirations herald a call for a paradigm shift from the existing extractive model to an inclusive sustainable marine model which maintains a “respectful” relationship with our oceans, inclusive of Māori values such as tikanga (customs and traditional values in a Māori context), rangatiratanga (self-determination, autonomy), kaitiakitanga, mana (authority, status, influence) and mauri, (divine spark, force or energy) to name a few. Results from the field studies showed that legal-sized tuangi have not been harvestable within Ōhiwa since the mid-1980s. There is an urgent need for integrated culturally responsive marine management actions. My study highlights the importance of the local traditional knowledge in identifying tohu (here I define tohu as a “observable cue,” an expression of mana, or mauri, communicated through the environment) for rapid broad-scale mapping techniques for habitat monitoring and assessment locations. These techniques can be scaled up and prioritise areas of interest within harbours, depending on species and/or objectives. The use of technology to interpret and analyse population dynamics confirmed Elders’ knowledge of the species and spaces within Ōhiwa Harbour. The Tīwaiwaka framework developed to address the declines of tuangi has provided an exemplar for the weaving together of multiple knowledges for shellfish management within Ōhiwa Harbour. This model of transdisciplinary estuarine and coastal regeneration, inclusive of Indigenous Knowledges such as mātauranga Māori, fulfils global conservation initiatives such as Article 8(j), of the Convention of Biodiversity, and the United Nations Decade of Oceans Science for sustainability, creating “the science we need for the ocean we want” as robust scientific-based solutions. Creating new knowledge through the weaving of mātauranga Māori, marine science and technology provides a pathway for transformative environmental change. The weaving of Indigenous Knowledge, ecological assessment and species distribution modelling generated new insights into tuangi populations and identified priority monitoring and restoration sites. The observational tohu identified are long standing environmental indicators that enabled rapid site assessment and the recognition of areas of significance. While tohu have long informed Māori environmental kaitiakitanga, this research formalised their application within contemporary conservation practice. More broadly, the Tīwaiwaka framework demonstrates a transferable Indigenous-led model for marine conservation, co-management and knowledge co-development that maintains the integrity of multiple knowledge systems while delivering culturally grounded, scientifically robust solutions for environmental governance and biodiversity conservation.