70040 research outputs found
Sort by
Bushfire-enhanced wind load on building structures
No full textThe present thesis aims to explore the fundamental mechanisms governing the interaction between the fire-enhanced wind and residential low-rise structures, with a focus on the aerodynamic load on the roof and smoke transport. For this purpose, an immersed boundary - lattice Boltzmann method - finite difference method (IB-LBM-FDM) is developed, and applied to three scenarios at high Reynolds numbers (Re > 2.5 × 105).
To address the intense computational cost of high-fidelity fire simulations, an efficient
geometry-adaptive multi-block solver is developed by employing the Boussinesq approximation and the volumetric heating and smoke source models for fire and smoke modeling, respectively. The solver is specifically designed for high temperature gradient flows
with ground effects using wall-modelled large eddy simulation (WM-LES) and is vali-
dated against extensive numerical and experimental benchmark cases with/without a fire
showing satisfactory accuracy for the scales of fire considered in this study.
Chapter 3 explores the role of fire-enhanced wind on the aerodynamics of a gable roof
structure and designs a bio-inspired geometry modification to reduce the roof load. The
results show that the fire-enhanced wind can generate very high uplift forces on the building, about three times that of the wind-only cases. Inspired by flippers of humpback
whales, scalloping the edges of the building generates strong streamwise vorticity and
significantly improves the flow separation in both normal and oblique directions in both
wind-only and fire-enhanced wind conditions, leading to a reduction in overall roof load.
In chapter 4, the role of openings on both aerodynamics and smoke ventilation into the
building during a fire event is studied. It is found that the net pressure load on the building roof increases even with a small-sized windward opening. In addition, during fire events, buildings with multiple openings allow for more smoke to penetrate compared to those with single openings.
In chapter 5, a study on the effect of neighboring structures on the aerodynamics and
smoke ventilation around the structures in urban-like geometries is presented. A notable
increase in wind load of all buildings is found under the fire-enhanced wind condition
compared to the wind-only condition. A combined vortex-entraining and vortex-trapping
mechanisms are found to generate a downward flow that allows smoke to be entrained and trapped from the smoke plume in the wake of the last row of buildings
Real-Time Gait Planning and Control of Bipedal Mechanisms: Applications for a Transformable-Wheel Robot
No full textIn this thesis, we develop a novel method for generating real-time orbital trajectories for bipedal robots in dual-stance or single-stance. We then apply this method to a class of balancing robots with reconfigurable wheel profiles. The hybrid locomotion mechanism in question allows a wheel rim to unfold into a set of radially-projecting claws, which assists with obstacle traversal. Our method is based on some modest modeling assumptions, and exploits the Adomian decomposition method to determine an approximate solution to the robot dynamics. As a result, we derive a unique manifold that represents the set of Poincaré fixed points. This structure, which we term a fixed-point map (FPM) is parameterised by the gait period T, and describes the set of pendular initial conditions such that, after the completion of a step, the pendulum returns to the same conditions. To demonstrate the use of the FPM, we develop a model-predictive controller (MPC) which drives the robot state onto the FPM surface from large local neighborhoods. Controller performance is evaluated on a novel, high-fidelity simulation of a transformable-wheel robot in 3D space. Our controller was able to maintain balance of the robot during obstacle ascent and descent, while differentially steering the wheels, during dynamic, differential expansion of the wheels. These highly-complex motions were enacted under the influence of artificial sensor errors, external disturbances and parameter uncertainties
Integrated Path Planning and Localization for an Ocean Exploring Team of Autonomous Underwater Vehicles With Consensus Graph Model Predictive Control
No full textNavigation of a team of autonomous underwater vehicles (AUVs) coordinated by an unmanned surface vehicle (USV) is efficient and reliable for deep ocean exploration. AUVs depart from and return to the USV after collaborative navigation, data collection, and ocean exploration missions. Efficient path planning and accurate localization are essential, the latter of which is critical due to the lack of global localization signals and poor radio frequency (RF) communication in deep waters. Inertial navigation and acoustic communication are common solutions for localization. However, the former is subject to odometry drifts, and the latter is limited to short distances. This paper proposes a systematic approach for localization-aware energy-efficient collision-free path planning for a USV-AUVs team. Path planning is formulated as finite receding horizon model predictive control (MPC) optimization. A dynamic-aware linear kinodynamic motion equation is developed. The mathematical formulation for the MPC optimization is effectively developed where localization is integrated as consensus graph optimization among AUV nodes. Edges in the optimized AUV-to-USV (A2U) and AUV-to-AUV (A2A) graphs are constrained to the sonar range of acoustic modems. The time complexity of the consensus MPC optimization problem is analyzed, revealing a nonconvex NP-hard problem, which is solved using sequential convex programming. Numerical simulation results are provided to evaluate the proposed method
A dual polysaccharide and plant protein system for cheese analog with enhanced meltability and texture
No full textCurrent commercial plant-based cheeses lack the dairy-like characteristics expected by consumers, often formulated with only starch and/or low protein content, underscoring the need for better solutions. This study presents a dual polysaccharide formulation with inclusion of plant-based protein to mimic the meltability of dairy-based cheese upon heating. A novel approach to starch addition into the emulsion gel was developed to ensure favorable network formations at each stage of cheese application, maximizing meltability and the creation of a soft texture after cooking. Pea protein isolate (PPI, 5 %), for O/W interface stabilization, worked in tandem with the network-forming glutinous rice flour (GRF, 0–12 %), and κ-carrageenan (κC, 0.2–0.8 %) in an emulsion gel that was tested for its mechanical properties at varying composition. Cheese-like characteristics were achieved through sequential gel-sol-gel transition κC and gelatinization of starch during cooking. Our PPI-κC-GRF emulsion gels showed excellent freeze-thaw stability (>85 %) and improvements over commercial plant-based cheese analogs in meltability (+12.39–115.75 % vs. −3.89 %, respectively). The study was able to track the changes in the structural formations of the two gel networks during cooking. Through rheology, confocal laser scanning microscopy, and Synchrotron-FTIR chemical imaging, a step-by-step map of the changes responsible for the meltability and texture of the emulsion gel was proposed. The results underline that dual polysaccharide network emulsion gel could be tailored to mimic cheese characteristics, as a possible template for future plant-based cheese development
Filtration and clogging behaviour: A systematic definition in the pore network
No full textThis study utilises graph concepts to provide a novel framework that characterises a key element of the filtration process: the clogging of finer base particles within the pore space of coarser filter particles. By utilising particle-scale data, a hyper-graph is generated that combines the filter pore network and the base particle contact network, through the use of graph components. This hyper-graph representation enables the identification of individual constriction status as empty, clogged, or percolating depending on the component membership. Using the constriction status and the connectivity of the pore network, the status of individual pores was defined as empty, clogged or non-clogged, and at capacity or with remaining capacity. This framework was developed in a highly generalised way to enable application to any numerical or experimental investigation of filtration that could generate the required particle-scale data. The proposed framework was applied to an extensive set of gravity-driven filtration simulations using the Discrete Element Method. This demonstrated that it was essential to account for constriction clogging and percolation, as well as, separately accounting for pore clogging and pore capacity status. An improved clogging criterion that accounts for base particle group effects is presented, and the existence of meso-scale relationships was demonstrated. These findings not only provide an improved understanding of the filtration mechanisms, but will also inform better particulate transport modelling and improved filter criteria that capture underlying mechanisms of filtration
Exploring the role of neuromuscular fatigue as a determinant of running performance and its interactions with metabolic cost, gait biomechanics, and running shoes.
No full textPerformance is a key focus of runners and researchers. In the laboratory it is analysed indirectly via determinants such as metabolic cost, neuromuscular fatigue, and gait mechanics. The metabolic cost of running (i.e., the energy expended during running) is a key determinant of performance, but it does not fully explain it. Therefore, this thesis explores an alternate determinant, namely neuromuscular fatigue, which is defined as a reduction in force or power output from a muscle. The relationships between fatigue, metabolic cost, gait biomechanics, and running shoes are explored in three studies (Chapters 3-5). Understanding how fatigue impacts performance is difficult, due to measurement challenges. A local fatigue protocol was therefore developed and implemented in Chapters 3-5. This allowed fatigue to be isolated to one muscle group and its relationship with metabolic cost (Chapter 3), metabolic cost and running shoes (Chapter 4) and joint mechanics (Chapter 5) to be explored. In Chapter 3, runners completed an unfatigued and fatigued run with plantar flexor and knee extensor fatigue. There was no change in metabolic power in the presence of fatigue for either muscle group. In Chapter 4 the effects of traditional and maximalist shoes on local plantar flexor and knee extensor fatigue were investigated for the same cohort. Fatigue recovery, measured before and after the fatigued run, was minimal for both muscle groups and shoe conditions. Also, as per Chapter 3, metabolic cost was unchanged. Finally, in Chapter 5 the effect of plantar flexor fatigue on positive joint work distribution during faster running, and the influence of advanced footwear technology (AFT) was evaluated. Running with, versus without, plantar flexor fatigue was associated with reduced positive ankle work and increased positive knee work. There was no effect of shoe condition. Local fatigue in key muscle groups does not appear to affect submaximal running performance and maximalist shoes do not alter this relationship or improve fatigue recovery. However, at faster paces, plantar flexor fatigue contributes to the adoption of altered gait strategies, which may impair performance. This research emphasises the complexity of running performance and provides new insights into the influence of fatigue
Digital health interventions for people who use methamphetamine: a scoping review
No full textIntroduction
Methamphetamine use is increasing and is associated with substantial health, social and economic harms. Despite these harms, many individuals delay or avoid treatment due to personal and systemic barriers. Digital health interventions (DHIs) are a promising avenue for expanding treatment access, however their application for methamphetamine use remains relatively underexplored. This scoping review aimed to identify and synthesise existing evidence on the feasibility, acceptability, and potential clinical impact of DHIs for people who use methamphetamine.
Methods
Four databases (Embase, PubMed, PsychINFO, and Scopus) were searched up to December 18, 2024. Eligible peer-reviewed studies examined DHIs aimed at reducing methamphetamine use and reported outcomes related to feasibility, acceptability, engagement, or clinical outcomes. Data were extracted and synthesised descriptively.
Results
Seventeen records (from 15 studies) reporting on 1269 participants (aged ≥18) across six counties were included. Women were underrepresented (180/1,217; 14.8%) in studies reporting gender. Most participants (772/1269, 60.8%) met study inclusion criteria for methamphetamine use; the remainder (497/1269, 39.2%) met diagnostic criteria for methamphetamine use disorder. Thirteen unique DHIs were identified including web-based programs (n=2), text messaging (n=2), smartphone apps (n=6), chatbots or virtual agents (n=2), and virtual reality (n=1). Cognitive behavioural therapy approaches underpinned 8 of 13 (61.5%) interventions, and 8 of 15 studies (53.3%) used randomised controlled trial designs. Most DHIs were feasible and acceptable, with high satisfaction reported. Initial engagement was generally strong but declined over time; dropout rates ranged from 7.3% to 67.7%. Clinical impact was mixed. Some DHIs demonstrated reductions in methamphetamine use, craving or improvements in cognitive functioning and help-seeking, with some sub-groups appearing to benefit more than others.
Discussion
DHIs show promise for people who use methamphetamine. While current evidence supports feasibility and acceptability, clinical outcomes are variable. High attrition and engagement challenges persist. Heterogeneity in study designs, measures, and reporting limits comparability. Future research should explore long-term outcomes, hybrid models, and co-designed approaches with a focus on gender and equity. With further development, DHIs may play a valuable role in the broader intervention landscape
The Four Dimensions of an Indigenous-State Treaty
No full textOn 13 November 2025, the First Peoples’ Assembly of Victoria and the State government signed the first formal treaty between an Australian government and Aboriginal and Torres Strait Islander communities. That same day, the Statewide Treaty Act 2025 (Vic), which gives legal effect to the Statewide Treaty, received Royal Assent and became law. But what are Indigenous-State treaties? In this article, I examine how Canadian courts characterise and interpret historic and modern treaties negotiated between the Crown and First Nations. Drawing on this jurisprudence, I argue that Indigenous-State treaties possess four dimensions. These agreements possess the qualities of a contract, a statute, an international agreement, and contain a constitutional character. When an Australian court is confronted with a dispute arising out of an Indigenous-State treaty, these four characters should be borne in mind
