UC Research Repository
Nau mai, haere mai, welcome to the UC Research Repository
The UC Research Repository collects, stores and makes available original research from postgraduate students, researchers and academics based at the University of Canterbury.
Communities
Select a community to browse its collections.
- Items from Journals and Conferences hosted by the University of Canterbury
- University of Canterbury Research Centres
Recent Submissions
The secret behind the spontaneous motion of droplets and its application to the design of lab-on-a-chip
(2025) Sellier M; Nock, Volker; Verdier C; Carnus J-M; Lamarche G; Rouault A; Tracey D
3D Robotic Control of Optical Swarms at Micro-Scale
(Institute of Electrical and Electronics Engineers (IEEE), 2025) Carlisle N; Nock, Volker; Williams MAK; Whitby CP; Chen JLY; Avci E
Optical force-induced assembly is a promising yet scarcely explored approach for developing functional tools and objects at the microscale, with a wide range of potential applications. Our previous work was the first to investigate the manipulation of these assemblies in the XY plane. Here, we expand on these techniques by systematically exploring optical trap manipulation with the addition of Z-axis control. Manipulation of the Z-axis is referred to as axial displacement and is a viable approach for actively manipulating the assembly morphology. Experiments are conducted for the first time to explore and detail the response of the assembly during active 3D trap manipulation, informing the development of an autonomous control algorithm over the 2D area of the assembly during motion. This control presents techniques to increase assembly stability or alter the area of the assembly for tasks such as passing through constrictions. This work aims to develop the control techniques required to create
a unique micromanufacturing approach inspired by the Kilobot thousand-robot swarm.
A critical state approach to characterise the liquefaction potential of sand-gravel mixtures
(2023) Chheda, Nainesh (Deena-Praful)
Gravelly soils’ liquefaction has been documented since early 19th century with however the focus being sand-silts mixture – coarse documentation of this topic, that gravels do in fact liquefy was only acknowledged as an observation. With time, we have been impacted by earthquakes, EQ causing more damage to our property: life and environment-natural and built. In this realm of EQ related-damage the ground or soils in general act as buffer between the epicentre and the structures at a concerned site. Further, in this area, upon the eventual acknowledgement of liquefaction of soils as a problem, massive efforts were undertaken to understand its mechanics, what causes and thereby how to mitigate its ill-effects. Down that lane, gravelly soils’ liquefaction was another milestone covered in early 20th century, and thus regarded as a problematic subject.
This being a fairly recent acknowledgement, efforts have initiated in this direction (or area of particle size under consideration-gravels>2mm), with this research outputs intended to complement that research for the betterment of our understanding of what’s happening and how shall we best address it, given the circumstances: socio (life) - environment (structures) - economic (cost or cost-“effectiveness’) and of course political (our “willingness” to want to address the problem).
Case histories from at least 29 earthquakes worldwide have indicated that liquefaction can occur in gravelly soils (both in natural deposits and manmade reclamations) inducing large ground deformation and causing severe damage to civil infrastructures. However, the evaluation of the liquefaction resistance of gravelly soils remains to be a major challenge in geotechnical earthquake engineering.
To date, laboratory tests aimed at evaluating the liquefaction resistance of gravelly soils are still very limited, as compared to the large body of investigations carried out on assessing the liquefaction resistance of sandy soils. While there is a general agreement that the liquefaction resistance of gravelly soils can be as low as that of clean sands, previous studies suggested that the liquefaction behaviour of gravelly soils is significantly affected by two key factors, namely relative density (Dr) and gravel content (Gc). While it is clear that the liquefaction resistance of gravels increases with the increasing Dr, there are inconclusive and/or contradictory results regarding the effect of Gc on the liquefaction resistance of gravelly soils.
Aimed at addressing this important topic, an investigation is being currently carried out by researchers at the University of Canterbury, UC. As a first step, a series of undrained cyclic triaxial tests were conducted on selected sand-gravel mixtures (SGMs), and inter-grain state framework concepts such as the equivalent and skeleton void ratios were used to describe the joint effects of Gc and Dr on the liquefaction resistance of SGMs.
Following such experimental effort, this study is aimed at providing new and useful insights, by developing a critical state-based method combined with the inter-grain state framework to uniquely describe the liquefaction resistance of gravelly soils. To do so, a series of monotonic drained triaxial tests will be carried out on selected SGMs.
The outcomes of this study, combined with those obtained to date by UC researchers, will greatly contribute to the expansion of a worldwide assessment database, and also towards the development of a reliable liquefaction triggering procedure for characterising the liquefaction potential of gravelly soils, which is of paramount importance not only for the New Zealand context, but worldwide. This will make it possible for practising engineers to identify liquefiable gravelly soils in advance and make sound recommendations to minimise the impact of such hazards on land, and civil infrastructures.
Multialgebras & related structures
(1979) Nolan, Francis Maurice
This thesis investigates the properties of two algebraic structures - multialgebras and partially ordered universal algebras. Multialgebras generalize the concept of a universal algebra to multivalued operations. Unlike universal algebras however there are many types of homomorphism associated with a multialgebra. A full homomorphism is defined and compared with the usual strong homomorphism of multialgebras. While they are similar in structure, the category of multialgebras and full homomorphisms is the dual of a category of boolean ordered algebras. This yields a more natural theory than that of the analogous category equivalent to multialgebras and strong homomorphisms.
Partially ordered algebras are universal algebras with a partially ordered base. They are treated from the view point of a universal algebra with an additional unary multi- operation (the partial ordering). In this fashion their peculiar properties can be explained by referring to either the universal algebra part or the multialgebra part. In particular the full and strong concepts of multialgebras are defined for the simpler structures and turn out to be dual notions.
Chapter 11. COVID-19, Community Health and Mitigating Climate Crisis
(MacMillan Brown Centre for Pacific Studies Press University of Canterbury, 2024) Crichton-Hill, Yvonne; Basu, Arindam; Ravono , Akisi; Vakamacawai , Esala
Climate change significantly impacts the health of Pacific peoples. These impacts
now need to be understood in the aftermath of a global COVID-19 pandemic.
To best understand the connection between the climate crisis, COVID-19 and
health, a holistic view of health encompassing the physical, mental, spiritual,
and social factors that influence health outcomes, is needed. Knowledge of the
impact of climate change on health continues to develop, however, positive health
adaptation strategies can also be found within Pacific Indigenous knowledge
and health models. Connecting understandings gained from the COVID-19 health
response, Pacific Indigenous knowledge and practices, alongside other scientific
knowledge will provide Pacific people with the best opportunity to successfully
mitigate climate and pandemic repercussions.