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The UC Research Repository collects, stores and makes available original research from postgraduate students, researchers and academics based at the University of Canterbury.
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Recent Submissions
Very Low Frequency Observations During an Active DC Injection Campaign that Simulated Geomagnetic Storm effects on High Voltage Transformers
(2023) Clilverd M; Cobbett N; Brundell J; Dalzell M; Lapthorn, Andrew; Hardie S; Agger P; Subritzky S; Beggan C; Huebert J; Eaton E; Rodger C
In January 2023, in collaboration with our industry partner Transpower Ltd (New Zealand’s national grid operator), a
campaign was undertaken to inject large currents into operating high voltage transformers. New Zealand’s high voltage
DC (HVDC) link was used to inject current directly into the ground at Haywards substation near Wellington, including
into several 216MVA 220 kV / 110 kV autotransformers. Six injection test periods occurred, each lasting 1-2 hours. The
peak current injected into the ground was about 621 A, spread across several transformers within the Haywards
substation.
The injection campaign was undertaken for New Zealand’s Endeavour programme “Solar Tsunamis: Space-Weather
Prediction and Risk Mitigation for New Zealand’s Energy Infrastructure”. The technique of substation monitoring using
nearby very low frequency (VLF) receivers has been previously reported by the lead author, based on observations of
the Halfway Bush substation (HWB) in Dunedin, New Zealand. Evidence of harmonic distortion through enhanced odd
and even 50 Hz harmonic amplitudes during geomagnetically induced current (GIC) events of up to 50 A, associated
with large geomagnetic storms in 2017 and 2018, have already been observed and analysed in detail. Typically,
enhancements in the amplitude of harmonics in the 100 Hz to 600 Hz range have been detected during GIC events. The
VLF observations from HWB are consistent with the idea that the local transformers radiate even harmonics of the 50 Hz
fundamental mains frequency due to half-cycle saturation driven by additive dc flux induced by GIC. During the Active
Injection campaign at Haywards Station, two identical VLF receiving systems were deployed around the substation.
Each VLF system comprised a set of orthogonal magnetic field loop aerials.
Preliminary results from the VLF harmonic data suggest that observed variations in amplitude in the 100 – 600 Hz
frequency range were correlated with temporal variations in the injected ground current, particularly after the current had
been applied for more than 20 minutes. Prior to that, a slow increase in harmonic distortion occurred, beginning at the
time of the injection onset. For injected substation earth currents ranging from 300 A – 600 A (about 20 A – 35 A for
individual autotransformers) even small variations of the order of 10’s of amps appeared to be well correlated with the
VLF amplitude variations of even order harmonics. In this study we present the VLF data during the injection events,
describing the responses observed from a large, complex substation experiencing geomagnetic storm-like effects.
Investigation of nonlocal granular fluidity models using nuclear magnetic resonance
(AIP Publishing, 2024) Clarke DA; Poata J; Galvosas P; Holland, Daniel
Nonlocal rheology models describe features in granular flows, such as scale dependence and flow below the yield point, that are not captured by local rheology models. It has been proposed that these features may be described by the transport of a property known as the granular fluidity. In this article, we studied an annular Couette shear cell of lobelia seeds using nuclear magnetic resonance to collect detailed measurements of the velocity distribution and volume fraction. These data were used to study nonlocal granular rheology models. We found that the nonlocal granular fluidity model was capable of accurately describing the decay in the velocity profile along the shear gradient direction. We also measured the dimensionless fluidity and validated the general form of the relation between this quantity and the volume fraction.
To the RescEU? Disaster Risk Management as a Driver for European Integration
(2024) Hopkins, W. John; Faulkner , Holly; Clausing , Silke
The European Union has incrementally expanded its role in the field of disaster risk management (DRM) since the late 1980s. This expansion has often been very slow as states have regularly challenged the EU’s growing role in an area traditionally seen as core member-state business. Nevertheless, the increasing inability of individual Member States to respond effectively to disasters led to the establishment of the Union Civil Protection Mechanism (UCPM) in 2001. The mechanism was significantly strengthened in 2019 with the establishment of the rescEU operational reserve and again in 2021 as a response to the COVID-19 pandemic. This article assesses the development of EU responsibilities in the field the DRM in the context of EU integration. In particular, it asks whether increased risk from natural hazards is creating a new driver towards European co-operation and integration. Will disasters, ironically, play a significant role in ‘rescEU’ing the Union?
Does the "Nae Umeed" group intervention improve mental health and social participation? A pre–post study in Uttarakhand, India
(Cambridge University Press (CUP), 2023) Bailie , Christopher R.; Pillai , Pooja S; Goodwin Singh , Atul; Leishman , Jed; Grills, Nathan J.; Mathias, Kaaren
Abstract
There are few evidence-based interventions to support caregiver mental health developed for low- and middle-income countries. Nae Umeed is a community-based group intervention developed with collaboratively with local community health workers in Uttarakhand, India primarily to promote mental wellbeing for caregivers and others. This pre–post study aimed to evaluate whether Nae Umeed improved mental health and social participation for people with mental distress, including caregivers. The intervention consisted of 14 structured group sessions facilitated by community health workers. Among 115 adult participants, 20% were caregivers and 80% were people with disability and other vulnerable community members; 62% had no formal education and 92% were female. Substantial and statistically significant improvements occurred in validated psychometric measures for mental health (12-Item General Health Questionnaire, Patient Health Questionnaire-9) and social participation (Participation Scale). Improvements occurred regardless of caregiver status. This intervention addressed mental health and social participation for marginalised groups that are typically without access to formal mental health care and findings suggest Nae Umeed improved mental health and social participation; however, a controlled community trial would be required to prove causation. Community-based group interventions are a promising approach to improving the mental health of vulnerable groups in South Asia.
The effects of temperature and emersion on the respiratory physiology of the New Zealand lobster Jasus edwardsii in air and water
(1999) Pritchard, Michelle M.
The New Zealand lobster Jasus edwardsii is the basis of a major seafood industry, where the majority of lobsters caught are exported alive. There is a lack of physiological information regarding the design, management, transport and holding of live lobsters. The main aim of this study is to understand the effect of temperature and emersion on the respiratory physiology of the New Zealand lobster.
Resting oxygen consumption increased with acute temperature change. When Jasus edwardsii was exposed to 5°C lobsters experienced a cold coma. Diurnal rhythm had no effect on the resting oxygen consumption. Lobsters did not show metabolic temperature compensation, actually showed reverse or paradoxical compensation i.e. lowered M0 2 after 2 weeks in a cooler environment.
There was an initial decrease in oxygen consumption at 5°C, 12°C and 18°C following aerial exposure, this was followed by a partial recovery at 12°C and 18°C. Resting aerial oxygen consumption increased with temperature. L-Lactate and ammonia had accumulated in the haemolymph of lobsters at the end of each emersion period. Hence lobsters still rely on anaerobic metabolism even at temperatures as low as 5°C in air.
There was a initial decrease in Pa0 2 and the oxygen content of the haemolymph when lobsters were emersed. pH initially decreased at all three temperatures and then tended to stabilize. Lactate steadily accumulated in the haemolymph at the three temperatures.
The haemocyanin oxygen affinity increased during prolonged emersion (measured in vitro at a constant pH). This increase was probably due to a rise in lactate concentration of the haemolymph.
Oxygen coductance of the gills decreased on emersion at 12°C but was partially restored between 4 and 24 hours. However, the rate oxygen consumption of lobsters
during emersion was not affected by the quantity of water in the branchial chamber. Thus it is concluded that the major factor leading to restoration of MO2 in air is lactate-induced increase in the affinity of haemocyanin for oxygen.
This study developed the understanding of the effects of temperature on the metabolism of the New Zealand lobster Jasus edwardsii in air and water. The information in this study is useful to the design and management of future lobster holding facilities.