Engineering: Journal Articles
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Item Open Access Developing a Stochastic Two-Tier Architecture for Modelling Last-Mile Delivery and Implementing in Discrete-Event Simulation(MDPI AG, 2022) Lyu, Z; Pons, Dirk; Chen, J; zhang, yileiModelling freight logistics is challenging due to the variable consignments and diverse customers. Discrete-event Simulation (DES) is an approach that can model freight logistics and incorporate stochastic events. However, the flexible delivery routes of Pickup and Delivery (PUD) are still problematic to simulate. This research aims to develop last-mile delivery architecture in DES and evaluate the credibility of the model. A two-tier architecture was proposed and integrated with a DES model to simulate freight operations. The geographic foundation of the model was determined using Geographic Information Systems (GIS), including identifying customer locations, finding cluster centres, and implementing Travelling Salesman Problem (TSP) simulation. This complex model was simplified to the two-tier architecture with stochastic distances, which is more amenable to DES models. The model was validated with truck GPS data. The originality of the work is the development of a novel and simple methodology for developing a logistics model for highly variable last-mile delivery.Item Open Access Disjointed Equivalence of Gravitational and Inertial Mass(Scientific Research Publishing, Inc., 2023) Pons, DirkProblem—Contemporary physics offers no underlying reason for the equi valence of inertial and gravitational mass. Approach—The equivalence is examined from the new physics provided by the cordus theory, being a non-local hidden-variable (NLHV) theory. Mathematical formalisms are de rived for masses and observers in different fabric densities. Findings—A dis jointed equivalence is predicted, whereby inertial and gravitational masses are equivalent in any one situation, but a different equivalence holds when the fabric densities change. Consequently this theory predicts that the gravita tional constant G varies with fabric density, and hence would be different across the universe and across time. Not only is the gravitational constant non-constant, but the formulation of gravitation changes with fabric density. Specifically, the theory predicts gravity is stronger at genesis (and the end of the universe) such that orbit velocity B B v r ∝ (where Br is orbit radius), compared to weaker gravitation at middle life epochs with 1 B B v r ∝ . The current Earth location and epoch correspond to the latter case, i.e. Newtonian gravitation is recovered. The findings disfavour the existence of both dark energy and dark matter, and instead attribute these effects to differences in the fabric density. Originality—The work makes the contribution of deriving a mass equivalence relationship that includes fabric density, identifying a dis jointed mass equivalence, and showing that the gravitation formulation itself changes with relative fabric densities.Item Open Access Geotechnical characterization and liquefaction evaluation of gravelly reclamations and hydraulic fills (Port of Wellington, New Zealand)(Elsevier BV, 2020) Dhakal, Riwaj; Cubrinovski, Misko; Bray , Jonathan D.In the 2016 Mw 7.8 Kaikōura earthquake, widespread liquefaction occurred in the reclamations at CentrePort, Wellington (New Zealand), while less intense shaking during two earthquakes in 2013 produced only some liquefaction manifestation over isolated areas of the port. The two types of reclamations, comprised of end-dumped gravelly fills and hydraulically placed silty-sandy fills, are not well represented in current empirical simplified liquefaction procedures. Comprehensive CPT investigations are presented and used to characterize the fills, and then perform CPT-based liquefaction evaluation for the three earthquakes that affected the port in 2013 and 2016. The results of the analyses are compared to observations of liquefaction performance and are examined in relation to the soil and deposit characteristics of the fills. The CPT-based liquefaction assessment was generally consistent with observations, though clear shortcomings and limitations of these procedures were also evident. The paper scrutinizes conventional engineering procedures for liquefaction assessment when applied to non-conventional or problematic soils for such assessment, with reference to a well-documented case history.Item Open Access Participatory modelling: precedents and prospects for civil engineering(Informa UK Limited, 2022) Avendano-Uribe , Bryann; Milke, Mark; Castillo-Brieva , D.This work provides an analysis for the civil engineering community of the practice of participatory modelling (PM), reviewing the advances that environmental researchers and practitioners have made over 20 years, providing key references, case studies, and practical guidelines. Past consultation methods have proven inadequate to build trust with communities, and have led to development of PM to improve engagement. Three lessons from PM are emphasised: (1) listen to stakeholders to better understand the system, (2) collaborate with stakeholders to better model the system, and (3) co-decide on actions to better empower and engage stakeholders. Advice on the key aspects to consider when designing a PM process is summarised. The challenges and obstacles to progress are analysed for PM in civil engineering applications. PM appears to be of greater value in larger projects involving complex socio-technical systems. The incorporation of PM within civil engineering work will be more useful to society when civil engineers understand better the operation of PM.Item Open Access Planning to adapt: identifying key decision drivers in disaster response planning(Informa UK Limited, 2021) Brown, Charlotte; Hayes , Josh L.; Milke, MarkTraditional disaster response plans are struggling to adapt to the increasingly complex, unique, and uncertain disaster impacts. Decision-making under deep uncertainty suggests the consideration of decision trigger points and adaptive processes to develop plans that are flexible for any oncoming challenge. Two disaster response planning situations are examined here: disaster waste management, and volcanic eruption clean-up. Both of these are examined in terms of how we can use adaptive processes to develop flexible plans oriented around key decision drivers. The indicators developed show that orienting plans around both hazard-centric drivers (level of earthquake shaking, ashfall depth) and impact-oriented descriptors (number of displaced people, hazard of waste) offer several benefits. Coupling the development of impact-oriented descriptors with scenario discovery and scenario planning will help disaster planners to identify key decisions, decision criteria and triggers that can be built into the planning process.Item Open Access A review, analysis and extension of water activity data of sugars and model honey solutions(Elsevier BV, 2020) Subbiah , Balaji; Blank , Ursula K.M.; Morison, KenWater activity is a physical property measured in the food industry which helps predict shelf life and microbial activity. Honey normally has a water activity less than 0.6, but this can vary with the amount of crystallization in solution. The aim of this work was to obtain relationships, as fundamental as possible, that can be used to predict the water activity of solutions with compositions similar to honey. Water activity measurements of aqueous sucrose solutions have been well analysed in literature using hydration theory. The analysis based on hydration numbers was easily able to show the quality of data previously published, and hence relationships were proposed for the hydration numbers of glucose, fructose, maltose and glycerol. A model was proposed in this study, to predict the water activity of food systems containing high concentrations of sugars and some electrolytes. The model was analysed and validated using mostly literature data supplemented with new experimental data.Item Open Access The engineering of CO2 hydrogenation catalysts for higher alcohol synthesis(2024) Tan, Angie; Isnaini MD; Phisalaphong M; Yip, AlexAnthropogenic CO2 emissions have drawn significant attention in recent years. Using CO2 as feedstock for chemical processes has become a key solution in overall closed carbon cycles for a vision of a circular carbon economy. CO2 hydrogenation to higher alcohols has emerged as one of the most promising CO2 conversion pathways for mitigating CO2 emissions and producing value-added chemicals. The present review critically discusses the most recent cutting-edge catalyst development in higher alcohol synthesis (HAS), focusing on the influence of different metals, promoters, and supports according to the contributions of different active species in modern catalyst configurations. Particularly, the critical roles of oxygen vacancies and the reaction mechanisms shed light on the rational design of the next-generation CO2 hydrogenation catalysts.Item Open Access Assessing wood grain and twist in a 2-year-old Eucalyptus bosistoana breeding population(Springer Science and Business Media LLC, online-publication-date) Sharma , Monika; Dijkstra , Stephanie M.; Garrill , Ashley; Collings , David A.; Altaner, ClemensInterlocked grain affects stem properties and timber value. Eucalyptus bosistoana is an emerging plantation species that is supported by a breeding programme, and which shows prominent interlocked grain. Grain assessments are difficult, either restricted in their spatial resolution or resource demanding. Comparative analysis of flexible and high-resolution X-ray microtomography grain measurements were shown to match the economical splitting test. Splitting demonstrated that, on average, grain in the 2-year-old E. bosistoana trees was straight close to the pith becoming slightly left-handed over the first 4 mm, but then developing a strong right-handed twist reaching an average of almost 5° by 12 mm. There was, however, a large degree of variability. Further, grain measures obtained from splitting tests correlated to the observed twisting of the stems. Lastly, twisting of timber was under genetic control. The combination of a heritability (h2 ) value of 0.34 and a coefficient of genetic variation value (rg) of 44% means that our assessment techniques for young trees could be incorporated into a breeding programme.Item Open Access A qualitative study of the machine operator’s experience of wellbeing in the New Zealand logging industry(Scion, 2024) Best, Trevor; Visser, RienBackground: Prompted by the need to reduce exposure to the physical hazards of the logging workplace, more of Aotearoa New Zealand’s loggers now find themselves operating a machine rather than working ‘on the ground’. This change has enabled more production to be achieved with less workers and with a significant reduction in the rate of serious harm incidents. However, mechanisation is not without its risks to operator wellbeing. This study explores the wellbeing of operators and the psychosocial demands and coping adaptations that contributed to that experience. Methods: Twenty-seven operators were recruited from three regions to participate in a semi-structured interview to explore their experiences of stress and wellbeing. References with consistent meaning were first, coded, and then, using Axial Coding, themes or categories were identified. Defining properties for each of these categories were then used to conceptualise the relationships between the themes. Results: Stress and wellbeing were described as a specific set of experiences resulting from the adaptations participants made in the face of threats to production, a sense of place within the crew and to family wellbeing. Those adaptations were arranged in two pathways that were dependent on what resources were available to the participants. If left entirely to their own skills and time, the participants would cope with threats by working longer hours. If through the decisions their forest owner / manager and contractor made, they had access to sufficient supply chain capacity, work security and job control supported by an effective organisational culture and interpersonal relationships, they could access the work-life balance that was at the heart of their sense of wellbeing. Conclusions: This research has provided an inventory of the psychosocial hazards faced by logging machine operators working in Aotearoa and the resources that enable them to cope. In doing so it has suggested that the potential for operator wellbeing is established in the designing of the overall supply chain (skids, roads, logging equipment configuration, and truck capacity) and the contracts that connect the various services, and then achieved through the way logging businesses are led and managed.Item Open Access Forest restoration at the Cass Mountain Research Area, Canterbury, New Zealand(2023) Evison, David; Wyse She School of Forestry has initiated a long term forest restoration project at the Cass Mountain Research Area (CMRA), an area of 1,775 ha in the upper Waimakariri basin owned and administered by the University of Canterbury (UC). In August 2022, 656 mountain beech seedlings were planted on a part of Remus Hill (an area of approximately 70 ha within the CMRA) by members of the student Forestry Society (FORSOC), assisted by UC staff and others. To support this planting programme, small seedlings had been previously gathered from a local site on UC land, then grown on for two years in a local nursery. Subsequently, the area was flown by a drone to produce a high-resolution digital elevation model of the planted area. The trees were measured and geo-located by fourth-year undergraduate students three weeks following planting, and measurements were made of the associated cover (species, proximity and height of cover species). Survival assessment and other measurements were made by second-year undergraduate students approximately six months following planting, at which stage 75% of the seedlings were surviving. Traps to study the invertebrate ecology and populations in the area have also been established by School of Forestry postgraduate students. The School of Forestry plans to hold a forest restoration field trip at Cass each year, to carry out planting, weed control and other activities consistent with the objective of restoring the previous forest cover on Remus Hill. Because the focus is forest establishment, activities that are necessary to ensure the survival of trees already planted may take precedence over additional planting. Further field visits, including measurement and analysis, will be incorporated into School of Forestry teaching in forest ecology and restoration. Long-term research projects will be developed, as well as opportunities for Honours and postgraduate research.Item Open Access Playing With Uncertainty: Facilitating Community‐Based Resilience Building(Cogitatio, 2022) Avendano‐Uribe B; Lukosch, Heide Karen; Milke, MarkResilience has become a fundamental paradigm for communities to deal with disaster planning. Formal methods are used to prioritise and decide about investments for resilience. Strategies and behaviour need to be developed that cannot be based on formal modelling only because the human element needs to be incorporated to build community resilience. Participatory modelling and gaming are methodological approaches that are based on realistic data and address human behaviour. These approaches enable stakeholders to develop, adjust, and learn from interactive models and use this experience to inform their decision‐making. In our contribution, we explore which physical and digital elements from serious games can be used to design a participatory approach in community engagement and decision‐making. Our ongoing research aims to bring multiple stakeholders together to understand, model, and decide on the trade‐offs and tensions between social and infrastructure investments toward community resilience building. Initial observations allow us as researchers to systematically document the benefits and pitfalls of a game‐based approach. We will continue to develop a participatory modelling exercise for resilience planning with university graduate students and resilience experts within academia in Christchurch, New Zealand.Item Open Access Using Everyday Objects as Props for VirtualObjects in First Person Augmented Reality Games: An Elicitation Study(2023) Greenslade, M; Clark, A; Lukosch, StephanIn this paper, we present an elicitation study which explores how people use common household objects as props to control virtual objects in augmented reality first-person perspective games. 24 participants were asked to select items from a range of common household objects to use as controllers for three different types of virtual object: a sword, shield, and crossbow. Participants completed short gameplay tasks using their selected items and rated the AR experience using the Augmented Reality Immersion (ARI) questionnaire. Results found no strong consensus linking any specific household object to any virtual object across our test group and, in addition, those who chose the most commonly selected object for each task did not have significantly higher scores on the ARI questionnaire compared to those who did not. A short post-experiment interview indicated a few key factors that were important to participants when selecting their household object, such as shape, size, grip feel and weight distribution. Based on our findings we recommend that developers provide the ability for users to choose which household objects to use as props based on the user’s own preferences, and that they design intuitive ways for users to interact with virtual objects.Item Open Access Immersive competence and immersive literacy: Exploring how users learn about immersive experiences(Frontiers Media SA, 2023) Steed A; Archer D; Izzouzi L; Numan N; Shapiro K; Swapp D; Lammiman D; Lindeman RWWhile immersive experiences mediated through near-eye displays are still a relatively immature medium, there are millions of consumer devices in use. The level of awareness of the forms of the interface and media will vary enormously across the potential audience. Users might own personal devices or might encounter immersive systems in various venues. We introduce the term immersive competence to refer to the general practical knowledge and skills that users accumulate about how typical immersive interfaces work—the ways in which buttons are used, main locomotion techniques, etc. We then introduce the term immersive literacy to refer to awareness of how immersive interfaces are unique, when they might be appropriate, typical forms of media, etc. We sketch out how users develop competence and literacy with immersive media, and then highlight various open questions that are raised.Item Open Access Tutorial video use by senior undergraduate electrical engineering students(Informa UK Limited, 2016) Martin, Philippa AnneThis paper looks at the impact, use and design of tutorial videos for two cohorts of senior undergraduate electrical engineering students. The videos are designed to augment in-person lectures and tutorials. This allows more problems to be covered or previously covered problems to be revised. We investigate how the videos impact student performance, whether students attempt problems before, during or after the videos and how students use the videos. We find that students use the tutorial videos in a variety of ways, including some that were unexpected. Results show wide spread use of the tutorial videos and indicate that students customised their learning environment to suit their needs, using both in-person and online resources. The value of tutorial videos on difficult concepts and troublesome knowledge is particularly clear. This highlights the importance of providing additional resources for such concepts and knowledge in order to improve student achievement. Different video design approaches and suggestions for further enhancements are also presented.Item Open Access CountShoots: Automatic Detection and Counting of Slash Pine New Shoots Using UAV Imagery(American Association for the Advancement of Science (AAAS), 2023) Hao, X; Cao, Y; Zhang, Z; Tomasetto, F; Yan, W; Xu, Cong; Luan, Q; Li, YThe density of new shoots on pine trees is an important indicator of their growth and photosynthetic capacity. However, traditional methods to monitor new shoot density rely on manual and destructive measurements, which are labor-intensive and have led to fewer studies on new shoot density. Therefore, in this study, we present user-friendly software called CountShoots, which extracts new shoot density in an easy and convenient way using unmanned aerial vehicles based on the YOLOX and Slash Pine Shoot Counting Network (SPSC-net) models. This software mainly consists of 2 steps. Firstly, we deployed a modified YOLOX model to identify the tree species and location from complex RGB background images, which yielded a high recognition accuracy of 99.15% and 95.47%. These results showed that our model produced higher detection accuracy compared to YOLOv5, Efficientnet, and Faster-RCNN models. Secondly, we constructed an SPSC-net. This methodology is based on the CCTrans network, which outperformed DM-Count, CSR-net, and MCNN models, with the lowest mean squared error and mean absolute error results among other models (i.e., 2.18 and 1.47, respectively). To our best knowledge, our work is the first research contribution to identify tree crowns and count new shoots automatically in slash pine. Our research outcome provides a highly efficient and rapid user-interactive pine tree new shoot detection and counting system for tree breeding and genetic use purposes.Item Open Access Practitioner perspectives on sea-level rise impacts on shallow groundwater: Implications for infrastructure asset management and climate adaptation(Elsevier BV, 2024) Bosserelle , Amandine L.; Hughes, MatthewClimate change is causing sea levels to rise, posing an unprecedented threat to coastal communities and infrastructure from coastal flooding and other hazards. The impact of sea-level rise on coastal shallow groundwater and subsequent impacts on infrastructure assets is a challenge that is not well understood. Semi-structured interviews were conducted with infrastructure engineers, asset managers and climate adaptation scientists from city- to regional-scale government organisations to capture their understanding of shallow groundwater impacts and adaptation responses to these current and anticipated issues in New Zealand. The study shows that groundwater already poses challenges to infrastructure asset managers. These issues are saltwater intrusion, flooding, increased liquefaction hazard, vulnerability of stormwater, wastewater management, drainage systems and coastal protection and long-term planning and financing. Climate change and sea-level rise will exacerbate these current and future issues. A key issue is who will take responsibility for shallow groundwater management in the face of new challenges from growing climate risks. This study highlights current approaches to manage groundwater variability will continue to be applied in future adaptation strategies. Further, groundwater monitoring and infrastructure asset management approaches to adaptation are limited less by technical understanding and more by political and economic considerations.Item Open Access Effects of fuel distribution on thermal environment and fire hazard(2024) Khan, Aatif Ali; Nan , Zhuojun; Zhang , Xiaoning; Usmani , AsifFire accidents in buildings are occurring and claiming thousands of lives each year. Due to various architectural designs, fire hazards would be unique to each building layout. This paper discusses how fire hazard varies with the arrangement of the fuel inside buildings. To comprehensively present the effect of fuel distribution on fire behaviour, results from large-scale experiments, bench-scale experiments, empirical correlations, and numerical studies are provided. In large-scale fire tests, two different cases of wood cribs were tested to demonstrate the effects of porosity on heat generation and fire spread behaviour. Due to the limitations of experimental conditions, the variation in heat release rate attributable to differences in fuel porosity and surface area has been also qualitatively investigated using a cone calorimeter test. To bring the gap between experimental observations and real-word scenarios, a numerical study is also performed. This study further explores the effects of fuel distribution (considering porosity and surface area of fuel throughout the compartment) and ventilation on fire spread beyond the fire compartment. The computational fluid dynamics (CFD) simulations show how the distribution of fuel in different ways can lead fire to spread beyond its origin, as observed in many fire accidents. The paper suggests that designers should consider such critical fire scenarios in performance-based design.Item Open Access Liquefaction hazard of Wellington reclamations based on conventional analysis(New Zealand Society for Earthquake Engineering, 2024) Cappellaro, Claudio; Dhakal, Riwaj; Cubrinovski, MiskoSevere liquefaction-induced damage occurred in reclamation fills at the port of Wellington (CentrePort) in the 2016 Kaikoura earthquake, but little or no damage was reported in areas of older and shallower reclamations in central Wellington. Recent studies have therefore primarily focused on understanding the liquefaction hazard of the port, while little is still understood with regards to the fill characteristics and liquefaction potential of the Wellington reclamations outside CentrePort. This study utilizes data from comprehensive field investigations, including 58 new cone penetration tests (CPTs) performed both within and outside the port in the Wellington waterfront area, supplemented with over 100 CPTs from our previous studies at CentrePort, to characterize the liquefaction resistance of the reclaimed fills in Wellington. The geotechnical data is first used to define simplified schematic soil profiles and to determine characteristic CPT parameter values (25th-50th-75th percentiles) for fills encountered in different reclamation areas. These analyses highlight differences in the soil profiles, and the relative similarity in the estimate of liquefaction resistance based on conventional CPT-based assessment, of fills encountered in different reclamation areas despite differences in the age, techniques, and materials employed in the construction of these reclamations. Conventional liquefaction assessments of reclamation fills based on CPT data are then performed over the wider waterfront area for a range of earthquake scenarios and ground motion intensities relevant for Wellington. For recent, past earthquakes, correspondence between predicted and observed severity of the manifestations of liquefaction vary depending on the earthquake event and area of observations. Likelihood of liquefaction occurrence and severity of the effects of liquefaction are then discussed for characteristic return periods, in the context of the seismic hazard of Wellington.Item Open Access Liquefaction characteristics of sand-gravel mixtures: Experimental observations and its assessment based on intergranular state concept(Elsevier BV, 2024) Pokhrel , Abilash; Chiaro, Gabriele; Kiyota , Takashi; Cubrinovski, MiskoCase histories from at least 28 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 potential and cyclic strain accumulation characteristics of gravelly soils remains a major challenge in geotechnical earthquake engineering. To provide new and useful insights into this crucial topic, stress-controlled undrained cyclic triaxial tests were conducted on sand-gravel mixtures (SGM) having sand-dominated microstructure but different packing states (i.e., soil grain arrangement), which were obtained by varying the gravel content (GC) and relative density (Dr). The experimental results confirmed that both the GC and Dr have marginal (at low GC and Dr) to significant (at high GC and Dr) effects on the cyclic resistance ratio (CRR) of SGM, but highlighted the need to consider GC and Dr effects together. In this regard, the use of state parameters, such as the equivalent void ratio (ef(eq)) and equivalent relative density (Drf(eq)), were found to be suitable approaches to describe the combined effect of GC and Dr on CRR as they provide unique correlations for sand-dominated SGM irrespective of their packing states.Item Open Access The Fragile State of Industrial Agriculture: Estimating Crop Yield Reductions in a Global Catastrophic Infrastructure Loss Scenario(Wiley, 2024) Moersdorf J; Rivers M; Denkenberger, David; Breuer L; Jehn FUModern civilization relies on a complex, globally interconnected industrial agriculture system to produce food. Its unprecedented yields hinge on external inputs like machinery, fertilizers, and pesticides, rendering it vulnerable to disruptions in production and international trade. Such a disruption could be caused by large-scale damage to the electrical grid. Solar storms, nuclear detonations in the upper atmosphere, pandemics, or cyber-attacks, could cause this severe damage to electrical infrastructure. To assess the impact of such a global catastrophic infrastructure loss on major food crops (corn, rice, soybean, wheat), we employ a generalized linear model. The predictions show a crop-specific yield reduction between 15% and 37% in phase 1, the year after the catastrophe, assuming rationed use of fertilizers, pesticides, and fuel stocks. In phase 2, when all stocks are depleted, yields decrease by 35%–48%. Soybean is less affected in phase 1, while all crops experience strong declines in phase 2. Europe, North and South America, and parts of India, China, and Indonesia face major yield reductions, potentially up to 75%, while most African countries are less affected. These findings underscore the necessity for preparation by highlighting the vulnerability of the food system.