25813 research outputs found
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Tree Canopy Cover in Matamata 2024
No full textThis report was prepared by Professor Justin Morgenroth and Dr. Ning Ye at the School of
Forestry, University of Canterbury. The aim of this report is to provide local authorities in New
Zealand with a basic understanding of the urban tree canopy cover within their cities and towns
Development of highly active anodes for anion exchange membrane electrolysers to enable low-cost green hydrogen.
No full textOver recent years global efforts to decarbonise energy systems has intensified due to the
growing need to address the effects of climate change. Currently, over 95% of all hydrogen
production utilises the highly emissive steam methane reformation process. Hydrogen
generated from water electrolysis paired with renewable electricity presents a promising
alternative. Among the existing electrolyser technologies, anion exchange membrane water
electrolysis (AEMWE) is emerging as a cost-effective solution due to its ability to operate
using earth-abundant, non-precious metal catalysts, and low-cost cell components. However,
AEMWE is a relatively immature technology, requiring further optimisation to become cost
competitive with steam reformation.
An initial review of the literature revealed that significant variation in reported performance
and stability metrics hinders effective comparisons and makes it difficult to identify
whether observed improvements are genuinely material-related or simply a result of different
testing conditions, procedures, or reference baselines. To address this, a standardised testing
protocol was established and a benchmark membrane and electrode configuration were
identified. This preliminary work provided a consistent foundation for the experimental
investigations undertaken in this work.
The main objectives of this thesis are to optimise both the components and the system to
achieve high-performance, stable AEMWE operation using low-cost materials. A technoeconomic
model was employed to asses the cost drivers in AEMWE systems and identify
the most effective strategies in order to reduce the levelised cost of hydrogen (LCOH).
Since the efficiency, stability, and cost depend on current density, investigating how several
technical and economic parameters affect the LCOH allowed for the determination of key
cost drivers of capital and operational costs. This work identified the optimal current density
of 1.38 A cm-2 to achieve a compromise between stability and performance, resulting in an
initial LCOH of $5.79 per kg. Additionally, the model highlighted that greatest potential
for AEMWE to lower the LCOH in line with the Department of Energy’s cost target comes
from reducing the overpotentials of the oxygen and hydrogen evolution reactions. Since the
oxygen evolution reaction (OER) is slower, more kinetically unfavourable, and typically requires expensive rare catalysts such as iridium to effectively complete the reaction, this
work focuses primarily on optimising the anode to lower OER overpotentials.
Before optimising the anode, it was critical to establish an active and reliable cathode to
act as a consistent baseline for full-cell performance investigations. Cathodes were prepared
using spray-coating to create catalyst-coated substrate (CCS) and catalyst-coated membrane
(CCM) assemblies. The inks used Pt/C with Sustainion, PiperION, or Nafion ionomers at
several concentrations (2-25 wt.%). Although using Nafion in OH- conducting systems may
seem counterintuitive due to its proton-conducting properties, electrochemical testing showed
that Nafion consistently outperformed the other ionomers. Scanning electron microscopy
(SEM) found Nafion to produce the most uniform catalyst layers, while half-cell testing
found it to have the highest electrochemically active surface area (ECSA). An ionomer
content between 15-20 wt.% was found to be optimal, as agglomeration occurred at too
low or too high a concentration, increased resistance, and isolation of active sites. CCS
assemblies consistently outperformed CCMs and exhibited lower charge transfer resistance.
Overall, catalyst layer morphology presented to be the primary indicator of electrochemical
performance. The optimal CCS cathode using 15 wt.% Nafion served as the cathode electrode
in the subsequent work.
The techno-economic analysis determined there to be two main pathways for lowering
the cost of hydrogen produced via AEMWEs: lowering the anode OER overpotential, and
improving the long-term operational stability. To address these challenges, the composition of
Ni1.2Fe1.2-xMnx layered double hydroxides (LDH) anode catalysts was varied. The optimal
OER performance and stability was achieved by substituting a small amount of Fe with Mn
(Ni1.2Fe0.9Mn0.3 LDH). It exhibited a low overpotential (341 mV at 1 A cm-2) and Tafel
slope (52.9 mV dec-1) in half-cell testing and maintained a stable performance over 330
hours in full-cell AEMWE testing. Structural and electronic characterisation using SEM,
X-ray photoelectron spectroscopy (XPS), density functional theory (DFT), and in-situ X-ray
absorption near edge structure (XANES) indicated the elevated activity was due increased
oxygen vacancies, optimal charge distribution, and enhanced electron transfer, while the
oxidation state of Fe remains unchanged under oxygen evolution potentials, suggesting
the role of Fe for providing structural stability. Overall the results demonstrate tuning the
Ni:Fe:Mn ratio to enable the controlled design of efficient and stable LDH catalysts for
alkaline OER.
This optimised Ni1.2Fe0.9Mn0.3 LDH catalyst and a benchmark NiFe LDH were further
used to investigate a novel direct membrane deposition technique (DMD). Conventional
electrodes are typically fabricated ex-situ and then assembled into a cell, adding extra manufacturing steps and requiring solvents for ink preparation. In contrast, the DMD process
can be carried out ex-situ, while also offering the potential to create catalyst layers insitu.
By creating a concentration gradient over an anion exchange membrane (AEM) with
selective permeability, hydroxide ions diffuse through, react with a catalyst salt precursor, and
precipitate an LDH layer directly on the membrane surface. Deposition time was controlled
to enable a systematic assessment of how the electronic and physical structure evolves during
growth and how these changes ultimately determine electrochemical performance. SEM
revealed the time-dependent pH gradient imposed by the OH- flux through the AEM to be
the influencing factor of the film’s morphological evolution, with the LDH evolving from
a sheet-like baselayer through to flower-like structures that become more complex over
time. AEMWE testing identified the 3-hour deposition to achieve a balence of catalyst
loading and resistive losses for both NiFe and NiFeMn LDH, with NiFeMn LDH consistently
outperforming NiFe LDH. X-ray absorption fine structure (EXAFS) analysis found the
Mn incorporation to destabilize the NiFe lattice during early growth, generating oxygen
vacancies, shortening metal-metal bonds, and increasing the number of under-coordinated
sites before partial structural recover at longer deposition times, an effect not seen in the
more uniformly ordered NiFe LDH. Fourier transform infrared (FTIR) spectroscopy and
XPS found that the Mn-induced lattice disruption promoted interlayer carbonate uptake
and together with the resulting disorder improved stability and enhanced OH- adsorption
and charge transfer during OER. Overall, the results of this work highlight the complex
interactions between catalyst composition, lattice structure, and interlayer chemistry, and
how these factors collectively govern electronic properties, active site availability, and
ultimately OER performance in AEMWEs. Ultimately the developed DMD method from
this work demonstrates significant potential to be a low-cost, simple, and scalable process
for fabricating catalyst coated membranes, with applicability in both AEMWE research and
commercial manufacturing
Tree Canopy Cover in New Plymouth 2022
No full textResearchers at the University of Canterbury's School of Forestry assessed urban tree cover for
the 75 largest cities and towns in New Zealand. Each city has been sent a free, customised
report providing a baseline assessment of its tree canopy cover
Reflecting on the use of Tīvaevae research methodology in mathematics education: A multi-dimensional perspective
No full textOngoing challenges have been reported in relation to representation of diverse communities
in mathematics education and related careers including those of Pacific heritage. This article
maps reflections on how Tīvaevae as both an art form and research methodology can be
used to disrupt deficit theorising towards Pacific students in mathematics classrooms with
the goal of healing what Naepi and colleagues (2019) term the “broken pipeline”. This
includes considering how Tīvaevae can be used as a basis for mathematical task design to
integrate the everyday experiences and knowledge bases of Pacific peoples as well as a
means to connect to Pacific values during mathematics teaching and learning. A second
example provides a view of how the use of Tīvaevae research methodology coupled with a
participatory research methodology (photo-voice) facilitated Pacific children and their
families to become researchers of their own life-worlds. The article concludes by highlighting
how culturally grounded research methodologies such as Tīvaevae offer opportunities to
consider different ways of thinking about mathematics education
A detailed analysis and spectroscopic mode identification of selected β Cephei and SPB stars
No full textThis thesis presents a detailed spectroscopic and photometric study of the pulsational behaviour
of B-type stars, focusing on the β Cephei and Slowly Pulsating B (SPB) classes.
Spectra were obtained using the high-resolution HERCULES spectrograph on the 1.0m
telescope at ¯ Oteh¯ıwai Mt John Observatory and photometry from the Transiting Exoplanet
Survey Satellite (TESS). The study aims to identify pulsation frequencies, determine
mode geometries and examine how different observational techniques complement
one another in the analysis of stellar oscillations. Three representative targets – HD 29248
(ν Eridani), HD 28114 (V1143 Tauri) and HD 118716 (ϵ Centauri) – were analyzed to
characterize their oscillation properties and perform mode identification. Radial velocities
and line profile variations were extracted from multiple spectral lines and these were
combined with TESS light curves and analyzed to determine pulsation frequencies, amplitudes
and phases.
A spectroscopic mode identification was then carried out for each target. For HD 29248,
multiple β Cephei p-modes were confirmed, including the dominant radial mode and several
non-radial modes were identified with ℓ = 1–2. The second star, HD 28114, exhibits
low-amplitude g-mode pulsations consistent with SPB variability, with mode identification
indicating ℓ = 1–4 and m values spanning −1 to 1. For the third star, HD118716,
two dominant p-modes were detected at 5.896 d⁻¹ and 6.183 d⁻¹, identified as ℓ = 2,
m = 1 and ℓ = 3, m = 1, confirming its classification as a β Cephei star. The combined
use of spectroscopic and photometric data provides a coherent picture of the stars’
oscillation behaviour. This work highlights the value of multi-technique analysis in constraining
pulsation properties and advancing asteroseismic studies of B-type stars within
the β Cephei–SPB instability region
Minutes Matter for Risk to Life in Disasters-the experience from Aotearoa, New Zealand
No full textHuman casualties related to rapid-onset natural hazards are usually proportional to the number
of people directly exposed. Yet population mobility makes exposure difficult to assess due to
temporal and spatial variability. Population exposure is a crucial dimension of risk, and often the
dynamics of exposure are overlooked in disaster risk assessment and subsequent management.
Here, we quantify how disaster risk in Aotearoa New Zealand changes across multiple temporal
and a highly resolved spatial scales due to dynamic population mobility and observe the significant
influence it has on resulting risk
Speech and language therapists' assessment and management of paediatric dysphagia in New Zealand.
No full textIntroduction
Paediatric dysphagia encompasses a range of feeding and swallowing difficulties in
infants and children. Based on the current available literature, there are various methods of
assessing and managing paediatric dysphagia, with little information surrounding current practices in the New Zealand context. Previous research in the New Zealand context has focused primarily on services for infants and has identified considerable variation in clinical procedures (Peters et al., 2019). Therefore, this study aims to explore the current service delivery and clinical practices of speech-language therapists (SLTs) working with children
with dysphagia across New Zealand.
Methods
This study consists of two self-administered surveys that targeted SLTs who work
with the paediatric dysphagic population in New Zealand. Each survey consisted of
demographic questions, questions regarding assessment and management, and questions regarding evidence-based practice (EBP) and professional development (PD). Data were analysed using descriptive statistics.
Results
A total of 36 SLTs participated in both surveys (South Island, n = 14; North Island, n
= 22). Demographic analysis revealed that SLTs across both islands worked with varied
paediatric caseloads. However, North Island SLTs were more likely to work in main urban
and acute settings, while South Island SLTs were more involved in long-term communitybased care. Assessment availability and accessibility varied, with North Island respondents reporting greater availability of VFSS and FEES. In contrast, South Island clinicians often
required long-distance referrals or had no access to these tools. The frequency of use of these instrumental assessments mirrored accessibility, and most SLTs indicated their usage would
increase if accessibility improved. Management strategies, including positioning,
environmental modification, and responsive feeding, were commonly used across both
islands. However, oral motor techniques and diet modification showed variation. Barriers to
intervention included family adherence, limited experience, and staff implementation
challenges. Satisfaction with the evidence base and access to professional development opportunities was generally lower in the South Island compared to the North Island.
Conclusion
Based on the data collected, it is evident that there is a wide range of service delivery
variation across the South and North Islands. The results indicate differing clinical practice procedures, barriers to interventions, and professional development opportunities depending
on the location of work and the demographics that SLTs work with. These findings highlight the need for national clinical guidelines and competency frameworks to be implemented to
promote the standardisation of paediatric dysphagia care
What controlled the occurrence of more than 116,000 human-mapped landslides triggered by Cyclone Gabrielle, New Zealand?
No full textThis paper uses an extract of 116,655 landslide source
areas from the >160,000 human-mapped landslides contained in
the Version One (V1.0) landslide inventory triggered by Cyclone
Gabrielle (11–17 February 2023). It describes the analysis of the
human-mapped landslide distribution and the relationships
between landslide occurrence, their susceptibility factors, and their
hydrological forcing factors. The results show that rain is one of the
main controlling factors on landslide probability, but the relationship is complex. Our results show the amount of 24-h rain becomes
less important, relative to other landslide susceptibility factors, at
high (>220 mm) to very high (>330 mm) 24-h rainfalls, suggesting
that such extreme rain amounts may not drive the highest probability of landslide occurrence. Results also suggest that the 24-h
rainfalls experienced by some areas during Cyclone Gabrielle were
likely to have been sufficiently high enough to “overprint” antecedent soil water conditions. In these overprint areas, soil-water conditions prior to Cyclone Gabrielle rainfall may not have materially
influenced the spatial landslide distributions. The results from this
study suggest that during a storm, more intense rainfall may not
directly translate to increasing probability of landslide occurrence;
however, it may diminish the effect of pre-event soil water content
Tree Canopy Cover in Whanganui 2022
No full textThe aim of this report is to provide local authorities in New Zealand with a basic understanding of the urban tree canopy cover within their cities and towns
The ‘Clash of Nationalisms’ in the Contentious USA–Taiwan–China Relations
No full textWhy is it that cross-strait tension has been at its highest since the missile crisis of 1996? Why is the USA–Taiwan–China relations so contentious since 2016? This article argues that one oft-neglected factor—nationalism and identity politics—needs to be considered as a contributing factor to the heightened tension in this triangular relationship. In all three states, audience costs have significantly increased as domestic leaders and elites appeal to populist and nationalistic positions and rhetoric. Though studies of foreign policy often claim that ‘politics stop at the water’s edge,’ populist and nationalist rhetoric in the domestic politics almost always spill over to the international arena. The convergence of Trump’s America First and the US’ obsession with its global primacy underpins and drives America’s approach to its strategic competition with China. China’s continual reference to the hundred years of humiliation in the nineteenth century and early twentieth century and Xi Jinping’s ‘China Dream’ are ethnonationalist appeals that drives China’s fight for its ‘rightful place’ in the global pecking order. Taiwan’s deepening national identity and sociopolitical de-Sinicisation while contributing the development of a separate nation-state is a direct clash to the People’s Republic of China (PRC’s) claim of Taiwan as part of its one-China principle. This article will trace and examine the role of domestic nationalism and how it has contributed to make the Taiwan Straits a ‘hotspot’ in global geopolitics and geoeconomics