A contrast in sea ice drift and deformation between winter and spring of 2019 in the Antarctic marginal ice zone

Two ensembles of buoys, deployed in the marginal ice zone (MIZ) of the north-eastern Weddell Sea region of the Southern Ocean, are analysed to characterise the dynamics driving sea ice drift and deformation during the winter-growth and the spring-retreat seasons of 2019. The results show that although the two buoy arrays were deployed within the same region of ice-covered ocean, their trajectory patterns were vastly different. This indicates a varied response of sea ice in each season to the local winds and currents. Analyses of the winter data showed that the Antarctic Circumpolar Current modulated the drift near the sea ice edge. This led to a highly energetic and mobile ice cover, characterised by free-drift conditions. The resulting drift and deformation were primarily driven by large-scale atmospheric forcing, with negligible contributions due to the wind-forced inertial response. For this highly advective coupled ice–ocean system, ice drift and deformation linearly depended on atmospheric forcing. We also highlight the limits of commercial floating ice velocity profilers in this regime since they may bias the estimates of sea ice drift and the ice type detection. On the other hand, the spring drift was governed by the inertial response as increased air temperatures caused the ice cover to melt and break up, promoting a counterintuitively less wind-driven ice–ocean system that was more dominated by inertial oscillations. In fact, the deformation spectra indicate a strong decoupling to large-scale atmospheric forcing. Further analyses, extended to include the deformation datasets from different regions around Antarctica, indicate that, for similar spatial scales, the magnitude of deformation varies between seasons, regions, and the proximity to the sea ice edge and the coastline. This implies the need to develop rheology descriptions that are aware of the ice types in the different regions and seasons to better represent sea ice dynamics in the MIZ

Design and construction of a vibration data logging prototype board for overland conveyor belts

Includes bibliographical references (p. 124-131).Overland conveyor belt systems form a vital part of modern transportation systems in the mining and mineral processing industries. It is vital that the system is well maintained in order to minimise system downtime and maximise profit. The conveyor belt is the single most expensive item in the system. It must be monitored to pick up potential problems before they cause belt failure. The majority of conveyor belt monitoring methods identify belt failure events rather than belt failure causes. The purpose of this project was to research and design a belt condition monitoring board which could be physically embedded in the conveyor belt. This would then be used to monitor the condition of the conveyor idlers whose failure can result in major system damage. The venture was split into two areas of research: the design of a vibration data logging board and the design of a power generation system. The thesis focused on the design of a DSP vibration data logging prototype board, while S.A. Williams investigated the design of a power generation system

A robust implementation of the spatial pooler within the theory of Hierarchical Temporal Memory (HTM)

In this study learning reinforcement and noise rejection of a spatial pooler was examined, the first learning stage in a Hierarchical Temporal Memory (HTM) network. Hierarchical Temporal Memory (HTM) is a proposed model within the field of neuromorphic engineering. It describes a top down approach to understanding how the human brain performs higher reasoning and has application as a machine-learning algorithm. Final results displayed an increase in permanence values associated with the learning of the input pseudo-sensory signal and the system was able to accurately recognize the input signal with up to twenty percent of the binary data randomly modified. These results demonstrated conclusive evidence that HTM is a possible choice when machine intelligence is a system requirement

Contrasting sea ice drift and deformation between winter and spring in the Antarctic marginal ice zone

Two ensembles of buoys, deployed in the north-eastern Weddell Sea region of the Southern Ocean, are analysed to characterise the dynamics driving sea ice drift and deformation during the winter-growth and the spring-retreat seasons of 2019. The results show that although the two buoy arrays were deployed within the same region of ice-covered ocean, their trajectory patterns were vastly different. This indicates a varied response of sea ice in each season to the local winds and currents. Analyses of the winter data showed that the Antarctic Circumpolar Current modulated the drift near the sea ice edge. This led to a highly energetic and mobile ice cover, characterised by free-drift conditions. The resulting drift and deformation were primarily driven by large-scale atmospheric forcing, with negligible contributions due to the wind-forced inertial response. For this highly advective coupled ice-ocean system, ice drift and deformation linearly depends on atmospheric forcing. On the other hand, the drift in spring was governed by the inertial response as increased air temperatures caused the ice cover to melt and break up, within this less advective ice-ocean system. Moreover, the deformation spectra indicate a strong de-coupling to large-scale atmospheric forcing. Analysis, extended to include the datasets of deformation in different regions around Antarctica, indicates that for similar spatial scales the magnitude of deformation may vary between seasons, regions and the proximity to the sea ice edge and the coastline