Engineering: Conference Contributions
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Item 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, online-publication-date) 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.Item Open Access Using Linear Assignments in Spatial Sampling(2023) Robertson, Blair; Price, C; Brown, J; Reale, MItem Open Access NZ Urban Forest Initiative(2024) morgenroth, justin; Chapman, TobyItem Open Access Detecting and measuring fine-scale urban tree canopy loss with deep learning and remote sensing(2024) Pedley D; morgenroth, justin; Pearse GItem Open Access Improving Neural Network Classification of Native Forest in New Zealand with Phenological Features(2024) Ye N; morgenroth, justin; Xu CItem Open Access Numerical modelling of the dynamic behavior of gravel-rubber mixtures and their efficiency as liquefaction countermeasures(The Japanese Geotechnical Society, 2024) Paul SM; Chiaradonna A; Chiaro, GabrieleDevastating earthquakes, such as those that recently affected Turkey and Morocco in 2023, are among the deadliest natural disasters. In addition, liquefaction-induced damage induced by strong shakings further exacerbates economic losses and elongates the repairing time for structures and infrastructures. Consequently, improving foundation soils and strengthening structural elements are possible ways to enhance the resilient capacity of a building to resist seismic forces. The main goal of this study is to numerically investigate the behaviour of innovative synthetic materials, made by a mixture of gravel and granulated rubber, used as geotechnical seismic isolation (GSI) systems relevant to the mitigation of seismic risk. To this aim, numerical simulations of a well-known and instrumented gravelly site affected by liquefaction during the 1995 Kobe earthquake are performed using a pore water pressure model implemented in one of the most popular nonlinear software adopted for dynamic analyses. The analyses were carried out with and without soil treatment made by a mixture of gravel and rubber, showing the efficacy of the proposed intervention. The result of the study contributes to expanding the knowledge about mixture-composite materials and assessing the gravel-rubber mixtures (GRMs) as an effective mitigation treatment of seismic risk.Item Open Access Liquefaction and Reliquefaction Characteristics of Compacted Slightly-Weathered Heterogeneous Tephras(The Japanese Geotechnical Society, 2024) Sood S; Chiaro, Gabriele; Wilson T; Stringer MTephras of slightly-weathered nature are essentially silty-sand deposits with no to low plasticity. They can constitute variable gradations and geochemical compositions depending upon the type and extent of weathering of particles and minerals. Case histories of liquefaction events suggest that such sand and silty-sand deposits can liquefy and reliquefy by a succeeding seismic event. However, the liquefaction and reliquefaction characteristics of different compacted tephras for backfilling usage have not been largely investigated. This paper presents the results of a series of undrained cyclic triaxial tests on specimens of three tephras(two rhyolitic and one basalt-andesitic) sourced from the North Island of New Zealand. Specimens are compacted at 90 % degree of compaction, isotropically consolidated under 100 kPa effective confining stress and then subjected to the first cyclic loading phase until liquefaction is achieved. Following liquefaction, specimens are reconsolidated and reliquefied. The test results showed an increase in the degree of compaction after reconsolidation for the compacted tephra specimens. However, a non-unified change in the liquefaction resistance is observed for the tephra specimens, which is dependent on their geochemical composition (or degree of weathering value) affecting the stress level (CSR) required. The elementally identical rhyolitic Kaharoa ashes (White Kaharoa Ash – WKA – and Golden Kaharoa Ash – GKA) exhibited a decrease in the liquefaction resistance following the first series of loading cycles. Despite a similar reliquefaction response, the liquefaction resistance of GKA was significantly lower in comparison to WKA tephra due to its more weathered nature. On the other hand, the basalt andesitic Maungataketake Ash (MA) tephra, being the most weathered out of the three tephras, showcased an opposite trend of increase in cyclic resistance after initial liquefaction.Item Open Access Fourier Series Model for Facial Feature Point Land-Marking(Elsevier BV, 2023) Arabian H; Ding N; Chase, Geoff; Moeller KThe field of digital health apps, combined with intelligent learning systems, is new and expanding to incorporate a wide range of possibilities in different domains. An application in the field of digital therapy is for the incorporation of emotion recognition systems as a tool for therapeutic interventions. Adopting an individually tailored virtual world combined with a novel reward system in a gaming scenario, complemented with the technical affinity of most autism spectrum disorder (ASD) children makes a suitable atmosphere for therapeutic intervention. In this paper the use of image processing techniques coupled with Fourier models is used to generate point land-mark annotations on facial features in an image. The OULU-CASIA database was used for the analysis process. The images were first pre-processed based on previous work to reduce background noise and focus on the face. Afterwards a de-correlation stretch was executed to separate different features. A series of morphological, region detections and boundary traces followed. Fourier series models were used to transition the rough segmented pixel data into a smooth geometric representation. Twenty evenly distributed land-mark points are then selected from a fine mesh. Results showed that the geometric representation adhered to the segmented pixel data with a mean of 81.88% Dice similarity. The positive outlook highlighted the effectiveness of such a technique in automating the land-mark annotation process, which is tedious and time consuming. This method leads to explainable machine learning feature representations, which lead to more robust emotion recognition models.Item Open Access Examining the effect of sap sugar concentration on fibre embolism in sugar maple (Acer saccharum)(International Society for Horticultural Science (ISHS), 2024) Robinson , J. A.; Rennie , M.; Clearwater , M.; Holland , D. J.; van den Berg , A.; Watson, MatthewSugar maple (Acer saccharum) develops elevated pressures in response to repeated cycles of freezing and thawing. This pressure is theorised to develop due to compression of gas present within fibres. Due to surface tension the pressurised gas within fibres should rapidly dissolve. That the gas persists over time is believed to be due to an osmotic barrier present between fibres and vessels that prevents sucrose from diffusing into fibres. This creates sufficient osmotic pressure to prevent gas dissolution and so maintain fibre embolisms. In our work we examine this hypothesis using synchrotron based microCT to produce high-resolution three-dimensional images of stem segments. Using this technique, we directly resolved the gas present in the fibres. Subsequently we perfused stem segments with either water or 2% sucrose and re-imaged them to examine any changes in fibre embolisms. Additionally, we also looked at samples that were frozen for 2-3 months to promote fibre embolism development, and for comparison we look at paper birch (Betula pendula), a species that is thought to develop elevated stem pressures through a different mechanism than Acer. From the fresh stem segments, we observed fibre embolisms were indeed present, and that when perfused with sucrose solution there was little to no change in fibre embolisms, whereas in almost all cases perfusing with water led to partial or complete refilling of fibre embolisms, supporting the hypothesis. The frozen samples did not display complete xylem embolization, in contrast to expectations, and showed complete refilling upon perfusion with either solution, suggesting cell damage had occurred. The birch samples also showed fibre embolisms. These embolisms remained after perfusing with sucrose solution, and there was some evidence the fibre embolisms refilled upon perfusion with water, however more samples are required to confirm these observations.Item Open Access Sensor-Based Pavement Layer Change Detection Using Long Short-Term Memory (LSTM)(IOP Publishing, 2022) Patel , Tirth; Guo, Hongwei; Zou , Yang; van der Walt, Jacobus Daniel; Li, YuDuring construction, pavement projects often suffer from a lack of progress certainty, which leads to cost and time overruns. The pavement construction progress should be monitored in a timely and accurate manner to provide prompt feedback and ensure project success. However, current pavement construction progress monitoring practices (e.g., data collection, processing and analysis) are manual, time-consuming, tedious, inconsistent, subjective and error-prone. The previous research study was limited to only incremental road construction progress measurement. This preliminary study proposes a novel sensor-based method to identify pavement layer changes during construction using a time series algorithm for the approach development of automated as-built measurement of road construction. In this study, data were collected from generating various road construction scenarios in a controlled environment by simulating layer changes using a ground vehicle equipped with a laser ToF (time-of-flight) distance-ranging sensor. Subsequently, Long Short Term Memory (LSTM) was utilized on collected data for feature detection as 'layer up', 'layer down' and 'layer not changed' to classify road layer change. The experimental result demonstrates 84.91% as a promising overall average accuracy of road layer change classification on the control environment data, confirming the potential implementation suitability to detect pavement layers in real pavement construction projects. However, low-performance measures (low precision, recall and F1 score) of layer up and layer down suggest further improvement to enhance the robustness of the proposed model. This method can be extended to automate pavement construction progress monitoring by validating the proposed approach in a real case.