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Supportive communication between apprentices and supervisors: development of a digital role play game
No full textPurpose: This paper describes the development of a digital role play game (RPG) designed to help construction apprentices to better communicate with their supervisors about issues with the potential to impact on their physical and psychological health and safety. Design/methodology/approach: A participatory approach was adopted to utilise the knowledge and insights of the target users to inform the digital RPG development. Apprentices and supervisors were interviewed to identify characteristics of effective supervisor-apprentice communication, which became the RPG’s learning objectives. The scenarios constructed in the RPG were drawn from lived experiences shared by the apprentices in the interviews. During the development process, consultations were conducted with an advisory committee comprising of apprentices and supervisors to improve the realism of the RPG scenarios. Findings: Three scenarios were developed for the RPG. In each scenario, players are asked to make decisions at various interaction points about how the characters should respond to the unfolding and challenging situations. Scripts were developed for the game, which were acted out and motion captured to animate digital MetaHuman characters embedded in a virtual construction site. Two example situations are introduced in this paper to illustrate the development process. Originality/value: To our knowledge, the RPG introduced is one of the first applications of digital game-based training in the construction industry. The adoption of a participatory design approach ensures that the game content relates to real-world experiences. The digital RPG is highly interactive and engaging in nature and presents a novel approach to developing “soft” skills in construction.</p
A Wearable Personalised Sonification and Biofeedback Device to Enhance Movement Awareness
No full textMovement sonification has emerged as a promising approach for rehabilitation and motion control. Despite significant advancements in sensor technologies, challenges remain in developing cost-effective, user-friendly, and reliable systems for gait detection and sonification. This study introduces a novel wearable personalised sonification and biofeedback device to enhance movement awareness for individuals with irregular gait and posture. Through the integration of inertial measurement units (IMUs), MATLAB, and sophisticated audio feedback mechanisms, the device offers real-time, intuitive cues to facilitate gait correction and improve functional mobility. Utilising a single wearable sensor attached to the L4 vertebrae, the system captures kinematic parameters to generate auditory feedback through discrete and continuous tones corresponding to heel strike events and sagittal plane rotations. A preliminary test that involved 20 participants under various audio feedback conditions was conducted to assess the system’s accuracy, reliability, and user synchronisation. The results indicate a promising improvement in movement awareness facilitated by auditory cues. This suggests a potential for enhancing gait and balance, particularly beneficial for individuals with compromised gait or those undergoing a rehabilitation process. This paper details the development process, experimental setup, and initial findings, discussing the integration challenges and future research directions. It also presents a novel approach to providing real-time feedback to participants about their balance, potentially enabling them to make immediate adjustments to their posture and movement. Future research should evaluate this method in varied real-world settings and populations, including the elderly and individuals with Parkinson’s disease.</p
User-Preference Based Evolutionary Algorithms for Solving Multi-Objective Nonlinear Minimum Cost Flow Problems
No full textNetwork flow optimisation has various applications such as communication, transportation, computer networks and logistics. The minimum cost flow problem (MCFP) is the most common network flow problem, which can be formulated as a multi-objective optimisation, with multiple criteria such as time, cost, distance and risk. In many real-world scenarios, decision-makers (DMs) aim for solutions in a preferred region(s). Using a reference point(s) allows the algorithm to efficiently search in the vicinity of the preferred regions instead of the entire search space. This paper introduces evolutionary multi-objective algorithms (EMOs) by employing a novel probability tree-based representation scheme (denoted as PTbNSGA-II and PTbMOEA/D) to address multi-objective integer minimum cost flow problems (MOIMCFPs) incorporating nonlinear cost functions. We also propose user-preference based EMO algorithms to solve MOIMCFPs using preference information (denoted as r-PTbNSGA-II and R-PTbMOEA/D). Since the algorithms utilise preference-based information, they have significantly lower computational costs compared to those of conventional EMOs. The performance of the proposed methods is evaluated on a set of 30 MOIMCFP instances. The experimental results demonstrate the superiority of PTbNSGA-II over PTbMOEA/D in finding high-quality solutions as well as the superiority of r-PTbNSGA-II over R-PTbMOEA/D in efficiently finding the high-quality solutions close to the preferred region.</p
Examining the Relationship Between Migration and Wages in Australia
No full textGlobalisation has led to a significant increase in international migration, with migrants now accounting for approximately 3.6% of the global population (IOM Annual Report 2023). This movement of people has sparked debates about the potential impacts of migration on local labour markets and wages. While existing research has produced mixed findings, the general consensus indicates that the impact of migration on wages is generally modest.
Australia presents an interesting case study, having implemented selective migration policies aimed at addressing skill shortages. As a result, the country has a substantial migrant population that plays a significant role in the labour force. The various visa streams have historically been closely aligned with the country’s labour market needs that usually vary with economic conditions, industry requirements and regional needs. This thesis aims to provide a comprehensive investigation of the relationship between migration and wages in the Australian context, examining both aggregate and industry-specific links. In particular, the thesis explores the long-run relationships between migration and wages, while also considering the differential impacts of specific visa types and migrants’ country of origin. Building on this, the research then takes a deeper, industry-level approach to uncover how the migration–wage relationship varies across sectors with differing concentrations of migrants and skill levels.
Using time-series data for the period 1996–2022, the analysis of wages and net overseas migration in Chapter 3 indicates a stable long-run equilibrium relationship as well as short-run bidirectional causality. However, migration encompasses diverse visa streams, each with distinct characteristics and labour market impacts. Indeed, a further analysis by types of visa streams provides interesting insights. Migration under the (permanent) skill stream indicates a long-run equilibrium relationship with wages. In the short run, there is evidence of a causal relationship where wages can predict the number of (permanent) skilled migrants. However, such a relationship is not found with (temporary) skill migration. Migration under the student visa stream, on the other hand, exhibits a short-term bidirectional as well as a long-term equilibrium relationship with wages. This dynamic clearly reflects the unique position of international students, both by contributing to the labour market as workers and also by transitioning into potential future skilled migrants in the future.
Disaggregating migration by country of origin further enriches the understanding of the migration–wage nexus. For instance, a stable long-run equilibrium relationship as well as short-run bidirectional causality is observed between Asian-born migrants and wages. Migrants from Asian countries often engage in entrepreneurship, starting businesses that contribute to local economic growth by creating jobs and stimulating economic activity. The inflow of Oceania-born migrants is found to predict short-run wage changes but not vice versa, consistent with the fact that migrants from Oceania often have skills and qualifications that directly influence their employment and wage prospects in Australia. Additionally, the one directional causality running from wages to migration for European-born migrants reflects a more passive relationship, where competitive wages and job opportunities become an attraction for migrants.
In Chapter 4, the wage–migration relationship is further explored using an industry level approach. Using panel data from 19 industries for the period 2001–2019, the analysis suggests an overall positive relationship, with a 1 percentage point increase in the migrant workers (measured as a share of the labour force) leading to a 0.28? rise in weekly wages. However, the magnitude and direction of this impact vary significantly with industry-specific characteristics. A key insight is that the positive influence of migrants on wages is more pronounced in industries with a lower baseline of migrant employers compared to more migrant-intensive sectors. This indicates that the contribution of migrants, in terms of filling critical skill gaps, boosting productivity, and creating new economic opportunities, has a greater impact in those sectors that are less saturated with migrant workers. In contrast, the migrant-intensive industries may experience a smaller wage effect, as the increased supply of migrant labour can also exert downward pressure on wages. The analysis across industries with varying skill intensity provides further insights. In high-skill-intensive sectors, migration has a positive impact on wages, consistent with migrants complementing the domestic workforce and leading to positive wage outcomes. However, a negative relationship is found between migration and wages in low-skill-intensive industries, indicating that migrants could be close substitutes for domestic workers. This suggests that the composition and skill profile of the migrant workforce play a significant role in the migration–wage relationship.</p
Multi-Document Non-Factoid Question Answering
No full textThis thesis focuses on multi-document answer generation for non-factoid questions
(NFQs), a challenging task of generating answers to open-ended questions that can only
be answered by summarizing information from multiple supporting documents. We first
conducted an eye-tracking study on the user evaluation of passage-length answers to NFQs
and found that the overall answer quality depends on several aspects. To better understand
what makes an answer useful, we identified 12 aspects of answer quality and evaluated the
limitations of commonly used NFQA evaluation measures.
To enhance understanding of the categories of NFQs that people tend to ask, what form
of answers they expect to see in return, and what the key research challenges of each category
are, we developed the first comprehensive NFQA taxonomy constructed with a transparent
methodology and extensively evaluated via crowdsourcing. Our analysis of major NFQA
datasets shows that the most challenging NFQ categories are underrepresented.
To address this, we introduce WikiHowQA, a new multi-document NFQA benchmark
built on WikiHow, a website dedicated to answering “how-to” questions. We provide
strong baselines and propose a novel human evaluation framework that utilizes highlighted
relevant supporting passages to mitigate issues such as assessor unfamiliarity with the
question topic.
non-factoid question answering
We aim for this research to serve as the basis for redefining user interactions with search
engines, ultimately creating the answer retrieval systems users have long desired.</p
Shock Tube Fabrication and Ignition Delay Measurements of Ammonia-Air Mixtures
No full textClimate change poses a significant threat to civilisation, driven largely by the combustion of hydrocarbon fuels used in power generation, industrial processes, and transportation. Recently, there has been a growing focus on green fuels like ethanol, biodiesel, and hydrogen carriers such as ammonia for powering engines and heating systems. Ammonia is particularly promising due to its higher energy density compared to liquid hydrogen. Additionally, its century-long use as a fertiliser and industrial chemical makes it safer and easier to store and transport. There is, however, a lack of information available on the combustion properties of ammonia, such as autoignition delay time and branched chemical reaction rates.
In the work described herein, the design and fabrication of the RMIT University Shock Tube (RUST) is discussed. The goal of this research was to design and fabricate a shock tube suited for investigating auto-ignition delay times of ammonia at pressures
and temperatures found in real engines. The design methodology and features of subsystems like gas distribution, control system, and data acquisition has been discussed. An in-house gas dynamics tool based on shock equations was programmed to predict test conditions when driver and driven gas mixtures are used. A MATLAB program was developed to process pressure data from high-frequency piezoelectric transducers, calculating ignition delay using the steepest gradient method. The program identifies the autoignition point by locating the intersection between the test pressure line and the steepest rate-of-change of pressure signals from the transducer nearest the endwall. Engine conditions for ammonia combustion were defined using isentropic relations, and a test matrix was created for a temperature range of 500-1100 K and a pressure range of 10-120 bar. Through the course of the project, it was discovered that the test time of the RUST (∼2 ms) was not sufficient to measure ignition delay of ammonia at engine conditions and higher temperature conditions (1600 to 2100 K) were studied instead. Techniques like gas tailoring and driver extensions to extend test times of the RUST to up to ∼9 ms were discussed along with X-T simulations. A reasonable agreement was found between measured data and literature.
In addition to ignition delay measurements, novel theories for diaphragm deformation were proposed and compared with real experimental data. Two theories – one for elastic region and the other for plastic region were discussed and the deformation of polycarbonate diaphragms of varying thicknesses (0.015” to 0.040”) was recorded. The elastic theory over-estimated deflection in the plastic region while the plastic theory predicted deflection with a ± 9 % accuracy.</p
A Review of Integrated Photonic Devices Using Sb<sub>2</sub>Se<sub>3</sub>
No full textThe silicon photonic technology is a highly promising option for photonic integrated circuits and has attracted intensive interests, particularly since it can utilize complementary metal‐oxide‐semiconductor processing techniques and facilities, thereby realizing high‐density photonic integrations with low‐cost. Unfortunately, the thermo‐optic and the carrier dispersion effects, which are the typical means of tuning silicon photonics devices, bring the drawbacks of high power consumption and large device size due to the relatively weak effect with a small refractive index change and being volatile. For overcoming these drawbacks, phase‐change materials are introduced into silicon photonic devices, where VO2 and Ge2Sb2Te5 are the most commonly used ones. However, the key disadvantage of large loss resulting from them limits further improving the performances of integrated photonic devices. Therefore, Sb2Se3 has seen increasing interests recently in the design of silicon photonic integrated devices, benefiting from the advantages of having extremely low loss over the C‐band and being non‐volatile. In this paper, the trending recent studies about integrated optical devices are systematically reviewed using Sb2Se3, which are classified according to the device function.</p
Reducing the social inequity of neighborhood visual environment in Los Angeles through computer vision and multi-model machine learning
No full textNo description supplie
One-pot synthesis of defect engineered carbon nitride for highly efficient visible light photocatalysis
No full textContinued industrial growth along with population growth is putting pressure on clean water supplies. Photocatalysis is an eco-friendly and cost-effective technology that can treat polluted water. As a visible-light-responsive photocatalyst, polymeric carbon nitride (CN) has shown significant potential for photocatalytic pollutant degradation. However, the fast charge recombination, slow charge transport and relatively large band gap restrict its photocatalytic performance. To overcome these challenges and develop a highly efficient photocatalyst, CN with robust visible-light photoactivity was solvothermally synthesised through defect engineering by carbon doping and surface vacancy modification. The additional carbon induces charge delocalization for enhancing charge tranfer and broadens the wavelength range of absorbance. The introduction of surface cyano functionality (–CN) not only enhances charge separation but also serves as electron-rich sites, thereby facilitating the generation of superoxide radicals. The controlled introduction of the C dopant and surface cyano group by simply introducing citric acid and varying the LiOH volume during synthesis demonstrated their synergy in optimising the electronic structure and the charge transport. As a consequence, there was a substantial generation of superoxide radicals when exposed to visible light (wavelengths > 420 nm), facilitating the efficient photodegradation of pollutants, such as tetracycline and Rhodamine B. Furthermore, the defect-engineered CN exhibited exceptional performance in the degradation of real-world wastewater. These findings underscore the promising potential of engineered CN for the advancement of visible-light-driven water purification technologies.</p
Energy Efficiency and Sustainable Development in Coastal Areas: Interactive Building Facade with Low-Cost Phase Change Material
No full textThe climatic environmental problem poses a significant threat to coastal areas, the world's most pressing issue in the coming decades. One common climatic environmental issue in coastal cities is the thermal discomfort in summer seasons, which leads to excessive energy usage for cooling spaces. From this perspective, responsive architecture is about how architects design specific parts of the building that measure climate features through a sensor and then enable buildings to adapt their form or shape through actuators. However, the problem is that the responsive façade mainly concentrates on expensive and complicated electrical systems. The control mechanism for detection and actuation needs high-tech mechanical solutions and more energy usage during the whole process. Accordingly, there is a need to develop a responsive façade system where low-tech solutions help reduce high energy costs. This research aims to (i) develop a ventilated responsive double-skin façade in the coastal area where the detection and actuation happen without electricity to increase the air ventilation and (ii) decrease the temperature of the cavity space through bio-based Phase Change Material (PCM). In façade systems, bi-metals are used as actuators to react to actual environmental conditions, while PCM is used as thermal energy storage to create thermal inertia in cavity space. For these purposes, numerical investigations, including Computational Fluid Dynamics (CFD) and Finite Element Methods (FEM) alongside lab tests, were conducted to understand the interactive facade behavior and its relation to the PCM. Based on the results, bi-metals could increase the blinds’ movement, increasing the airflow in cavity space. From the physical experiment, a significant reduction in cavity temperature was observed in high temperatures by applying PCM compared to when it was not. It is expected to evaluate the system's effectiveness on the typical occupants' thermal comfort. Finally, it was found that placing the designed operable façade system in front of a room can increase airflow and provide thermal comfort for the residents. The outcome of this research could help architects better understand the modular louver blinds' behavior when integrated with actuators in the design stage to improve thermal comfort prediction using responsive façades in coastal areas.</p