Engineering: Conference Contributions
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Item Open Access Development of a 2D biomechanical model to simulate seated multidirectional arm strength of people with C5-C7 tetraplegia(Cambridge University Press (CUP), 2023) Stilwell, George; Symons, Digby; Gooch , ShaynePeople living with tetraplegia experience a significant loss of sensory and motor function; with the severity depending on their injury level and completeness. To complete tasks independently, people with tetraplegia often rely on assistive devices. To avoid upper extremity pain, designs should not require applications of force near the limits of the user's physical strength. This paper establishes a 2D biomechanical model using static equilibrium and joint torque limits to predict multidirectional strength patterns in the sagittal plane for people with C5 to C7 tetraplegia in a seated position. The results from the biomechanical model highlight the areas and directions of high strength. The strength patterns observed in this paper provide an opportunity for designers to evaluate strength requirements and take advantage of areas and directions of high strength and ensure that users are not required to apply force near their physical limit. In doing this, designs such as assistive devices can be developed that enable users with a reduction in strength to operate them independently.Item Open Access Evaluation of E-Scooter Tyre Performance Using Dynamometer-Based Coast-Down Tests(Cambridge University Press (CUP), 2023) Stilwell, George; Gooch S; Goodwin M; Zarifeh HE-scooters have become a popular form of personal transport with millions of E-scooters used worldwide. This paper details an initial investigation into the relative differences in rolling resistance for a range of e-scooter tyres. Tyre performance was measured using dynamometer-based coast-down tests to determine the coast-down distance and coefficient of rolling resistance of each tyre. Insights from testing showed that e-scooter tyres had coefficients of rolling resistance that were 3.5 to 6 times the coefficient of rolling resistance of a 700x32C bike tyre. Comparisons between tyres of similar specification showed the tyres with solid inserts had more rolling resistance than a pneumatic tyre at the rated pressure. Comparisons of equivalent airless and pneumatic tyres the rated pressure indicated airless tyres had slightly better performance in terms of coast-down distance. The results also show how a decrease in tyre pressure increases rolling resistance, highlighting the importance of maintaining rated tyre pressure to improve e-scooter efficiency. The results from this study provide useful insights into the performance of tyres that can be used on low-powered vehicles.Item Open Access Comparison of e-scooter tyre performance using rolling resistance trailer(Cambridge University Press (CUP), 2024) Stilwell, George; Gooch S; Lafitte ME-scooters are a cost-effective means of urban transport, however, there have been questions about their safety, performance, and energy efficiency. This paper investigates the rolling resistance of scooter tyres so that the performance of scooters can be more accurately determined. A rolling resistance trailer was manufactured to directly measure tractive force and closely approximate the rolling resistance force for nine commonly used scooter tyres at low speed on a smooth concrete surface. The results of this study will enable a better understanding of the energy losses of these devices.Item Open Access Rethinking reactor design: additive manufacturing applications in chemical engineering(2024) Watson, Matt 5389Item Open Access Semiconductor Device Fabrication Lab Demonstration during and after COVID-19(2024) Chen L; Hayali A; Adams R; Wislang K; Hou C; Alkaisi M; Nock, Volker; Allen MCONTEXT The Solar Cell Lab is a vital element of the popular ENEL491 Nano Engineering course offered by the Electrical and Computer Engineering at the University of Canterbury. The course and associated lab introduce and demonstrate basic semiconductor device fabrication processes to 400-level students. The lab has attracted students from multiple departments and the number of enrolled students increased from less than 20 in 2012 to nearly 70 in 2024. Students fabricate and characterise solar cells from a plain silicon wafer received at the beginning of the lab session. PURPOSE OR GOAL To minimize virus transmission and, at the same time, maintain the quality of the delivered teaching. To ensure students have the opportunity for sufficient hands-on experience in semiconductor fabrication processes, the measures described were implemented during the COVID-19 pandemic. APPROACH OR METHODOLOGY/METHODS The original arrangement of the lab demonstration was designed for fully immersive face-to-face delivery. There were 2 streams with 6 to 8 groups of students (2 or 3 per group) per stream depending on numbers. Students are expected to attend 1 stream for a duration of 3 weeks, learning different fabrication techniques. Each student will submit a report individually at the end of the three weeks of labs. After the pandemic, the maximum number of students for each stream was reduced to 6 students per stream and the number of available streams increased to a maximum of 12 streams. In addition, videos were recorded during wafer preparation and lab sessions, and made available via UC Learn, thus maintaining student engagement during mandatory COVID-19 isolation. ACTUAL OR ANTICIPATED OUTCOMES There are better interactions between the teaching assistants (TAs) and students after the change in the arrangement. Students are more likely to ask questions during lab sessions when the maximum student number per stream decreases. With the change in lab session arrangements, students were able to work on each process step without time pressure, allowing for a more hands on experience, with students thus receiving more information transfer from TAs and staff. CONCLUSIONS/RECOMMENDATIONS/SUMMARY Before the pandemic, students were allocated less than 12 minutes per group per step. After changes were implemented, better interactions with students could be observed during lab sessions, and the TA workload could be better balanced for preparation between sessions, thus providing a better work/rest balance. Interestingly, despite challenges experienced during the pandemic, students were still able to achieve similar solar cell performance compared to pre-COVID years.Item Open Access Effects of thickness on the energy dissipation efficiency of GSI(2024) Chiaro, Gabriele; Forcellini , D.; Palermo , A.; Banasiak , L.Geotechnical seismic isolation (GSI) using gravel-rubber mixtures (GRM), as an energy dissipative horizontal layer, is a foundation system that can enhance the seismic resilience of low-rise residential buildings. This paper presents the results of a numerical study carried out to evaluate the seismic performance of a selected GSI(VRC40) system (having volumetric rubber content of 40%) and compare it to that of a standard foundation system placed on a compacted gravel layer (i.e., without rubber). To this scope, a 3-dimensional FE model is implemented in OpenSees and calibrated using experimental data. In the model, a 12 m × 6 m × 0.5 m concrete raft foundation is placed on a layer of VRC40 with varying thicknesses (i.e., 0.6, 1.2, 1.8, 2.4, 3.0 and 3.6 m). No structures are considered in this study. The model is subjected to a ramped sinusoidal input base acceleration (ab = 0.1 - 0.5 g) at different frequency levels (f = 1 - 8 Hz). The accelerations at the base (aGIS,base) and top (aGIS,top) of the GSI layer are measured and it is found that the seismic performance of the GSI system significantly increases with increasing ab and f, as well as the GSI thickness, as the GSI(VRC40) layer is able to drastically reduced the acceleration transmitted at the GSI top (i.e., at the base of the concrete raft) as compared to that of the non-isolated gravel foundation. Using a recently proposed GSI efficiency index (EGSI), the effect of the thickness on the energy dissipation efficiency of GSI(VRC40) systems is further examined and it is found that GSI(VRC40) layers of 1.2‒1.8 m thicknesses represent cost-effective foundation systems to significantly reduce the seismic load on/improve the seismic performance of low rise-residential buildingsItem Open Access Mechanical Behaviour of Well-graded Gravel-rubber Mixtures in Static and Cyclic Fields(2024) Abate G; Chiaro, Gabriele; Fiamingo Angela; Massimino MRThe necessity to repurpose End-of-Life Tires (ELTs) has driven researchers to seek new methods for converting them into useful products. Recently, shredded rubber from ELTs has been increasingly utilised in various civil engineering fields due to its valuable mechanical properties. Over the past few years, numerous experimental tests have been conducted on the use of shredded scrap tyres mixed with poorly-graded granular soil, primarily sand or gravel, as backfill material for retaining walls, liquefaction mitigation, structural fill, and geotechnical seismic isolation (GSI). Many studies in literature have focused on the mechanical properties of sand-rubber mixtures, while limited research has been done on the behaviour of gravel-rubber mixtures. This paper aims to explore the physical and mechanical properties of more economic and easy-to-prepare geomaterials combining well-graded gravel mixed with scrap rubber grains (wgGRMs) through isotropically consolidated drained monotonic and cyclic triaxial (TxCD and CLTxT) tests. The tests were carried out by varying the confining pressure and the volumetric rubber content (VRC). The results highlight the effect of confining pressure and VRC on the stress-strain relationship and volumetric and cyclic behaviour.Item Open Access Quantifying tree-level Eucalyptus defoliation using UAV LiDAR(2024) Pariyar S; Xu C; Pawson S; Morgenroth, Justin; Ye NItem Open Access Enhancing Individual Tree Detection and Species Classification in an Urban Forest with Semi-Supervised Deep Learning Models(2024) morgenroth, justin; Zhao H; Pearse G; Schindler JItem Open Access Extremely large post-liquefaction deformations of saturated sand under cyclic torsional shear loading(2009) Chiaro, Gabriele; Kiyota , Takashi; De Silva , Laddu Indika Nalin; Sato , Takeshi; Koseki , JunichiThe effect of static shear stress on the undrained cyclic behavior of saturated Toyoura sand was studied by conducting a series of torsional shear tests up to double amplitude shear strain of about 100%. After being isotropically consolidated, the specimens were subjected to drained monotonic torsional shear loading, and then, cyclic torsional shear stress was applied under undrained condition. The amplitude of combined static and cyclic shear stress was kept constant by correcting the measured value for the effect of membrane force. Based on these test results, it was found that the effective stress path and the stress-strain curve were affected by the initial static shear stress. Accumulation of shear strain was clearly noticed in the same direction where the static shear stress was applied. Localization of specimen deformation, which increases with the shear strain level, was observed.Item Open Access What Determines VR Integration in Design Practice? An Investigation of Industrial Designer's Acceptance of VR Visualisation Tools(Cambridge University Press, 2023) Zhang, Wendy; Ranscombe C; Piumsomboon, Thammathip; Mallya PEmerging visualisation tools based on eXtended Reality (XR) platforms offer designers new possibilities and benefits, attracting increasing interest from academia and industry. However, as the users and consumers of these tools, practising designers' perceptions of XR visualisation tools need to be further verified as they shape the tools' acceptance and integration in the industry. This paper investigates industrial designers' acceptance of VR visualisation tools using the Unified Theory of Acceptance and Use of Technology (UTAUT) model. Semi-structured interviews were undertaken with 12 designers from 3 countries to discuss their attitudes, motivations, experiences, and expectations regarding adopting VR visualisation tools as professional tools. The study highlights key opportunities to promote VR integration in industrial design as the tools' practical capabilities to support design performance and the social influence of stakeholders and peer designers on the professional use of VR. The main barriers lie in designers' expected effort to learn and use the tools and the investment and upkeep of VR systems and facilities in the industry. The paper concludes with recommendations for reaping benefits and overcoming barriers.Item Open Access Improving Neural Network Classification of Native Forest in New Zealand with Phenological Features(2024) Ye N; morgenroth, justinItem Open Access Enhancing Seedling Detection in New Zealand Forestry: A Multi-Datastream Approach(2024) Singleton B; Xu C; Ye N; morgenroth, justinItem Open Access Emotional Design in Transforming Excessive Social Media Use: A Case Study on Young Adults' Overuse of Short-Form Video Products(2024) Li H; Zhang, Wenwen; Shahri, Bahareh; Chen ZGrowing concerns have been raised about excessive social media usage among young adults and its adverse effects on mental health. Challenges persist in designing effective strategies to help young adults manage the overuse of social media, especially in the context of short-form video (SFV) products, where the issue is more pronounced. This study explores and discusses design strategies grounded in emotional design principles to assist young adults in managing the excessive use of SFV products, aiming to transform their relationship with social media into a more sustainable one. The study focuses on two main questions: 1) What factors influence young adults' excessive usage of SFV applications? 2) What emotional design-based strategies can effectively regulate this usage? An online ethnography was conducted to understand user motivations, behaviours, and the effectiveness of existing methods for managing overuse. The findings indicate that boredom is a significant factor driving the excessive use of SFV products, with users exhibiting varying levels of awareness and ability to control their usage. Integrating emotional and behavioural design principles, the study presents ‘Sustainable Design for User Emotion’ recommendations, highlighting key factors for developing effective design strategies to manage users' excessive use of digital products and promote healthier usage patterns. A broad survey was conducted with young adults aged between 18 and 35, further investigating the real-world usage patterns of SFV products and assessing the effectiveness of the proposed design strategies. The results offer insights and actionable recommendations for research and practice in responsible product design.Item Open Access Insulin pump accuracy at low and minimum delivery rates, in relation to paediatric diabetes care(Elsevier BV, 2023) Payne , Matthew; Pooke , Francis; Holder-Pearson, Lui; Chase, GeoffIncidence of Type 1 Diabetes is increasing rapidly in children. The uptake of insulin pump therapy as a treatment method amongst the paediatric population is also increasing quickly, surpassing the rate of uptake in other groups. Studies have shown varied results regarding the safety of insulin pump therapy in children and adolescents. A study was conducted to determine if delivery accuracy of insulin pumps can potentially affect glycaemic outcomes in younger users. Three insulin pumps were tested: a low-cost prototype pump design, and two commercially available insulin pumps at basal rates of 0.025 U/h, 0.1 U/h and 1 U/h. Bolus accuracy was also tested at a range of bolus sizes between 0.025 U and 1 U. Testing was completed in accordance with IEC60601-2-24, with some modifications made to improve accuracy and ensure results are more generalisable to real-world insulin pump use. Results showed large inaccuracies at smaller dose sizes and potential for insulin pump accuracy errors to cause a clinically relevant shift in blood glucose values, especially at the smaller dose sizes and basal rates used by children and those sensitive to insulin. Further testing is needed with a wider range of commercial insulin pumps to determine if these errors are present in all devices.Item Open Access Flexible external heat-pulse sap flow sensor for bi-directional measurement of sap-flow in small diameter stems(International Society for Horticultural Science (ISHS), 2023) Rennie M, M.; morgenroth, justin; Watson, MatthewAt present, most sap flow sensors are probe-based and therefore inappropriate with small diameter trees, where large comparative amounts of cross-sectional xylem will be disrupted by the probes and heat produced. While external non-invasive sap flow sensors can measure bi-directional flow in trees with diameters less than 10 mm, they are based on the heat ratio method derived from a line heat source. This presents the potential to create localised heating around the heat source, disrupting the natural flow of sap within the tree. Therefore, in this study, we propose a non-invasive sap flow sensor consisting of a ring heat source heating the circumference of the stem along with a modified heat ratio method. Calibration of the measured heat pulse velocity (𝒗𝒉) was conducted by gravimetric measurement of an imposed flow through sections of stem. Two species were examined: white poplar (Populus alba) and paper birch (Betula papyrifera). Preliminary results of the sap flow sensor show linear agreement of both species with their imposed flow, ranging between -20 to 20 g h-1.Item Open Access Questioning Urban Forest Canopy Cover Goals(2024) morgenroth, justin; Dobbs C; Doick K; Hauer R; Duinker PItem Open Access Emerging Trends in Freehand Sketch Usage within Contemporary Industrial Design Practice and Education(2024) Mallya P; Woods T; Zhang, Wendy; Shahri, BaharehTraditionally, freehand sketching has proven to be an indispensable method for industrial designers to generate, develop and communicate product concepts. However, the primacy of sketching in design practice is now challenged by accelerated workflows, advances in visualisation technology, and the evolution of the discipline from a product focus to a contemporary evolutionary trend towards product systems and services. How is this evolution in practice contributing to changes in the usage of traditional forms of industrial design sketching? If so, what are the implications for the future of sketching for design? Through a broad survey of award-winning industrial designers in New Zealand, this visual paper reveals a notable evolution in professional sketch usage in the following formats: (1) low-fidelity ‘rough’ sketches; (2) medium- to high-fidelity sketches; and (3) non-traditional 'non-object' sketches. These findings are additionally compared with taught sketching content in undergraduate degrees at universities, to reveal significant differences in how educators include each of these three formats within sketching modules.Item Open Access Understanding Poroelastic Stressing and Induced Seismicity with a Stochastic/Deterministic Model: an Application to an EGS Stimulation at Paralana, South Australia, 2011(2016) Riffault, J; Dempsey, David; Archer, R; Kelkar, S; Karra, STo create an Enhanced Geothermal System (EGS), cold water is injected at high pressure, along with acid, with the goal of reactivating pre-existing fractures and enhancing their permeability. Through increases in pore pressure and associated stress changes, shear failure occurs, which is part of the permeability enhancement process, but also results in induced seismicity. In spite of being the primary goal of stimulation, details about the spatiotemporal evolution of permeability are difficult to determine. One measure of its improvement is the increase in well injectivity, which is defined as the injected flow rate divided by the wellhead pressure. However, this measure is sensitive to both the volume of stimulated rock as well as the permeability increase, and so it does not uniquely constrain the stimulation state. To augment this analysis, we present an inverse modelling approach that incorporates both the injection records and the spatiotemporal distribution of induced seismicity. We present an application of the method to the Paralana-2 EGS stimulation undertaken in 2011 in South Australia. High pressure injection is modelled by solving coupled flow and heat transport equations in the reservoir simulator FEHM. In the model, the magnitude of permeability increase is a prescribed function of space and time. The injectivity profile observed at Paralana limits the possible set of permeability evolution scenarios, however, additional constraint is necessary to choose amongst these. As induced seismicity is a consequence of elevated pore pressure, we assume that the density of earthquake hypocenters is proportional to pore pressure rise. By comparing the pressure profiles modelled in the different scenarios to the high-resolution microearthquake data collected during the stimulation, we can pick the permeability enhancement distribution scheme most consistent with the injectivity and seismicity data.Item Open Access DESIGNING FOR UNSEEN USERS: ENHANCING NON-EXPERT RESCUERS’ EMOTIONAL EXPERIENCE IN CARDIAC ARREST EMERGENCIES(The Design Society, 2024) Chen , Zhen; Zhang, Wenwen; Coutts , Euan; Li , HongyaoGlobal ageing is leading to an increase in cardiac arrest incidents among senior citizens, posing a significant societal challenge. Most out-of-hospital cardiac arrest (OHCA) incidents occur at home, limiting patients' immediate access to professional help and Automated External Defibrillators (AEDs). In such instances, Cardiopulmonary Resuscitation (CPR) by caregivers, often the patient's family with no expert knowledge of emergency care, becomes crucial. Compared to professional rescuers, caregivers could face challenges in executing effective CPR due to skill gaps and emotional barriers in performing such procedures on family members. This study investigates the emotional experience of caregivers in cardiac arrest scenarios, a critical but often overlooked aspect in the design of emergency care devices. We aim to understand 1) how emotions affect caregivers' performance and experience during domestic cardiac arrest incidents, and 2) how design can support their practical and emotional needs, enhancing their performance. Semi-structured interviews with professional rescuers and non-expert caregivers reveal the emotional challenges that caregivers might confront before, during, and after cardiac arrest incidents, such as fear of approaching a collapsed person, anxiety about causing harm, lack of confidence, and moral pressure from social ties. These challenges can lead to adverse reactions that further hinder their CPR performance. The study highlights the importance of including emotional support for non-expert rescuers in OHCA incidents. By incorporating human-centred design principles, we propose an inclusive design guideline for emergency care devices and practical design strategies to mitigate emotional barriers and assist operational performance for non-expert rescuers.