4,934 research outputs found
Breaking Virtual Barriers : Investigating Virtual Reality for Enhanced Educational Engagement
Virtual reality (VR) is an innovative technology that has regained popularity in recent years. In the field of education, VR has been introduced as a tool to enhance learning experiences. This thesis presents an exploration of how VR is used from the context of educators and learners. The research employed a mixed-methods approach, including surveying and interviewing educators, and conducting empirical studies to examine engagement, usability, and user behaviour within VR. The results revealed educators are interested in using VR for a wide range of scenarios, including thought exercises, virtual field trips, and simulations. However, they face several barriers to incorporating VR into their practice, such as cost, lack of training, and technical challenges. A subsequent study found that virtual reality can no longer be assumed to be more engaging than desktop equivalents. This empirical study showed that engagement levels were similar in both VR and non-VR environments, suggesting that the novelty effect of VR may be less pronounced than previously assumed. A study against a VR mind mapping artifact, VERITAS, demonstrated that complex interactions are possible on low-cost VR devices, making VR accessible to educators and students. The analysis of user behaviour within this VR artifact showed that quantifiable strategies emerge, contributing to the understanding of how to design for collaborative VR experiences. This thesis provides insights into how the end-users in the education space perceive and use VR. The findings suggest that while educators are interested in using VR, they face barriers to adoption. The research highlights the need to design VR experiences, with understanding of existing pedagogy, that are engaging with careful thought applied to complex interactions, particularly for collaborative experiences. This research contributes to the understanding of the potential of VR in education and provides recommendations for educators and designers to enhance learning experiences using VR
Defining novel regulators of inflammatory signalling in pancreatic cancer
Pancreatic ductal adenocarcinoma (PDAC) remains a cancer with few effective therapeutic options and, for patients with this disease, the prognosis remains extremely poor. In recent years immunotherapy has emerged as a promising treatment modality for a number of different tumour types but so far its impact in treatment of PDAC has been limited. Examining the molecular pathways that determine the immune response to cancer cells in PDAC will enable development of new therapeutic strategies to target this response.
Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase that is elevated in human PDAC tissues and correlates with high levels of fibrosis and poor CD8+ T cell infiltration. The Serrels Laboratory has already demonstrated a role for FAK in promoting tumour evasion by inducing an immunosuppressive microenvironment, specifically by regulation of cytokines. This has led to trials of the FAK inhibitor (defactinib) in conjunction with immunotherapy. I proposed that FAK was likely to regulate further chemokine/cytokine and ligand receptor networks and that by understanding more about these networks it may be possible to target potential pathways to modify this response and provide therapeutic benefit.
I used CRISPR, Forward Phase Protein Arrays (FPPA) and ELISA on mouse and human PDAC cell lines to examine relative expression of chemokines and cytokines and how this expression was regulated by FAK. I identified CXCL16 as one of the most abundantly expressed cytokines in both mouse and human cell lines and one of the most significantly increased cytokines upon FAK depletion. PDAC FAK null cell lines +/- CXCL16 were then orthotopically implanted into the pancreas of C57BL/6 mice and I demonstrated that CXCL16 depletion resulted in a re-programming of the immune cell tumour infiltrate with reduced tumour growth. These findings identify a FAK dependent CXCL16-CXCR6 paracrine signalling axis that may represent a mechanism of resistance to FAK inhibition and thus an important potential therapeutic target
First-principles calculations of anharmonic phonons in diamond and silicon at high temperature and pressure
Many ab initio approaches for calculating anharmonic phonon dispersion relations have recently been developed, taking advantage of improvements in computational power. In this thesis, anharmonic phonons in the diamond-type semiconductors silicon and diamond are studied using two of these recently developed ab initio techniques to better understand the role of anharmonicity in these materials at elevated temperatures and pressures. The two techniques are the self-consistent phonon method as implemented in the alamode code and the temperature dependent effective potential approach implemented in the TDEP code. Both these approaches rely on density functional theory calculations to compute anharmonic phonon frequencies from first principles.
The renormalisation of the zone-centre optical phonon of silicon is calculated using both methods. The TDEP approach accurately reproduces the experimentally observed temperature dependence of the zone-centre phonon, whereas alamode underestimates the renormalisation. This underestimation is determined to originate from the exclusion of certain phononâphonon interaction processes in a series expansion central to the self-consistent phonon method. In particular, an interaction process involving three phonons is identified to contribute strongly to the anharmonic phonon renormalisation. An attempt was made to extend alamode to include this interaction, which was, regrettably, unsuccessful.
The TDEP approach is then applied to diamond in the same manner as silicon. The zone-centre optical phonon is calculated and a comparison to available experimental data is made. The approach is again found to accurately reproduce the experimental data. Consequently, the TDEP approach is used to investigate the so-called quantum isotope effect in diamond. Deviations from the harmonic frequency ratio of the zone-centre phonons are used to investigate the anharmonic nature of the interatomic potential, as well as to search for an experimentally suggested âinversionâ of the quantum isotope effect at high pressure. No such inversion of the quantum isotope effect is observed in the calculations made here. A detailed comparison of the effect of different exchangeâcorrelation functionals and pseudopotentials on the density functional theory calculations is made, ultimately recommending local density approximation as the most accurate predictor of phonon frequencies in diamond.
Finally, the Raman frequency of natural diamond is calculated at high temperature and pressure using the highly accurate TDEP method. Improvements are made to the stochastic sampling process, eliminating unwanted scatter from misaligned eigenvectors at degenerate points in the Brillouin zone and increasing the precision of the method. The calculated Raman frequency is used to suggest a calibration of the high-frequency edge of the Raman signal from a diamond anvil, which is used as a pressure marker in very-high-pressure experiments. The suggested calibration extends to pressures up to 1 TPa and temperatures up to 2000 K
Beam scanning by liquid-crystal biasing in a modified SIW structure
A fixed-frequency beam-scanning 1D antenna based on Liquid Crystals (LCs) is designed for application in 2D scanning with lateral alignment. The 2D array environment imposes full decoupling of adjacent 1D antennas, which often conflicts with the LC requirement of DC biasing: the proposed design accommodates both. The LC medium is placed inside a Substrate Integrated Waveguide (SIW) modified to work as a Groove Gap Waveguide, with radiating slots etched on the upper broad wall, that radiates as a Leaky-Wave Antenna (LWA). This allows effective application of the DC bias voltage needed for tuning the LCs. At the same time, the RF field remains laterally confined, enabling the possibility to lay several antennas in parallel and achieve 2D beam scanning. The design is validated by simulation employing the actual properties of a commercial LC medium
Laser absorption spectroscopic tomography with a customised spatial resolution for combustion diagnosis
Combustion is a widely used energy conversion technology. However, post-combustion gas emissions have adverse effects on climate change. To address the urgent need for carbon neutrality, efforts are being made to develop cleaner fuels and improve combustion efficiency. Accurate in situ measurements of temperature and species concentration are crucial for analysing and diagnosing the combustion process. In industrial applications, probed-based measurement methods are commonly used to detect temperature and species concentration in the combustion, favoured by their simplicity. However, the probe-based techniques are limited in their spatial resolution, as only point-wise measurements can be provided by them. Additionally, their principle often restricts their temporal resolution, which limits their ability to capture the dynamics of the combustion process. To overcome these limitations, researchers are actively working on developing rapid and multi-dimensional in situ techniques for temperature and species concentration monitoring.
Laser Absorption Spectroscopy (LAS) has gained significant attention for its non-intrusive nature and fast response in combustion diagnostics. LAS techniques use an emitter-receiver configuration to measure the line-of-sight light intensity absorbed by species in the gaseous medium. By collecting multiple line-of-sight measurements from different angles, LAS enables tomographic measurement of the combustion process. However, implementations of LAS tomography face challenges due to the physical dimensions of the emitter and receiver and the optical access to industrial combustors. These limitations lead to incomplete measurements, which are key factors of ill-posed problems and artefacts in the reconstructed images. The artefacts lead to inaccuracy and unreliability of the diagnostic results.
Increasing physical sampling density is one of the most straightforward ways to alleviate the ill-posed problem caused by inadequate line-of-sight measurements. Improvements in sensors have been demonstrated in previous research, such as optimising laser beam arrangement and reducing the spacing of neighbouring laser beams. In this work, a novel design of a miniature and modular sensor is firstly introduced. It reduces the beam spacing between adjacent laser beams, allowing for a more precise and detailed reconstruction of temperature and species concentration distributions. Meanwhile, modular design allows for customisation and adaptation to various measurement requirements. This flexibility in deployment reduces the cost of the LAS technique.
The application of small beam spacing in characterising the non-uniformity of the combustion process has also been demonstrated in this thesis. A multi-channel LAS sensor is developed and applied to exhaust measurements of a commercial auxiliary power unit. The results show that the small beam spacing allows a detailed understanding of the exhaust plume at the mixing zone between the exhaust gas and surrounding air. This spatial information can be used to improve the accuracy of temperature and species concentration measurements.
On the other hand, prior knowledge, such as smoothness and sparsity of the measurement target and beam arrangement of the LAS tomographic sensor is used to provide extra physical information to the ill-posed inverse problem. To incorporate the beam arrangement information into the reconstruction process, a new meshing scheme is proposed in this thesis. The scheme dynamically allocates smaller meshes in the beam-dense regions and coarser meshes in the beam-loose regions. This adaptive meshing scheme ensures a finer resolution in detailing the combustion zone where the beams are closely spaced while maintaining the integrity of the physical model by using less resolved reconstruction in the bypass flows or regions where the beams are further apart. As a result, the proposed meshing scheme improves the reconstruction accuracy of the combustion zone.
Overall, this PhD project designed and developed LAS tomographic sensors and methods that enable accurate and fast measurement of gas temperature and species concentration in combustion processes with a customised spatial resolution. The main contributions of this thesis include the design and prototyping of a miniature and modular optical sensor for flexible LAS tomography; the development of a multi-channel LAS sensor for simultaneously monitoring exhaust gas temperature and water vapour concentration in gas turbine engines; and the development of a size-adaptive hybrid meshing scheme to improve the reconstruction of target flow fields
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R&D and innovation capabilities in South African state-owned enterprises: the case of the South African National Energy Development Institute
Working paper series, no. 2b, FebruaryOne critical question addressed in the research contributing to this case study report is which dimension(s) could be instrumental in gearing SANEDI's R&D and innovation performance. As a small SOE that performs vital applied R&D, and other innovation activities, in a transforming and dynamic energy sector, collaboration with universities and other organisations is critical to gearing the SOE to use its R&D and innovation outputs to achieve its mandate more efficiently and effectively. Clearly, it is through collaboration that SANEDI can acquire
technological capability, resources, and infrastructure. But collaboration also helps SANEDI's R&D personnel acquire new knowledge and build capacity, and validate and quality assure its projects. Indeed, SANEDI's strong partnering function can, in part, be attributed to its robust R&D and innovation governance -that is, the generally effective and supportive management environment enabling the entity to secure the right collaborative partners and funding on an ongoing basis. Equally, a strategic approach, including the appointment of a new CEO beyond its interim appointments, is required to ensure the organisation selects the appropriate topics to co-invest or partner and does not 'spread itself too thin'.N/
Virtual Reality in Mathematics Education (VRiME):An exploration of the integration and design of virtual reality for mathematics education
This thesis explores the use of Virtual Reality (VR) in mathematics education. Four VR prototypes were designed and developed during the PhD project to teach equations, geometry, and vectors and facilitate collaboration.Paper A investigates asymmetric VR for classroom integration and collaborative learning and presents a new taxonomy of asymmetric interfaces. Paper B proposes how VR could assist students with Autism Spectrum Disorder (ASD) in learning daily living skills involving basic mathematical concepts. Paper C investigates how VR could enhance social inclusion and mathematics learning for neurodiverse students. Paper D presents a VR prototype for teaching algebra and equation-solving strategies, noting positive student responses and the potential for knowledge transfer. Paper E investigates gesture-based interaction with dynamic geometry in VR for geometry education and presents a new taxonomy of learning environments. Finally, paper F explores the use of VR to visualise and contextualise mathematical concepts to teach software engineering students.The thesis concludes that VR offers promising avenues for transforming mathematics education. It aims to broaden our understanding of VR's educational potential, paving the way for more immersive learning experiences in mathematics education
Multiphysics simulations of fire inside the cavity of a facade
The facade system is highly complex and requires achieving multiple objectives to provide occupants with a safe and comfortable environment. Any attempt to improve these objectives, such as aesthetic, thermal or acoustic insulation, could potentially affect the fire safety of the facade system. This is especially true as novel materials were introduced over the last decades, resulting in an ongoing rise in facade fires. Researchers have observed that a narrow cavity in a facade system encourages rapid facade fire spread. Unfortunately, there is little knowledge of quantifying the impact of cavities on a facade fire. Computational Fluid Dynamics (CFD) fire simulation represents an excellent tool to complement experimental studies on fire inside a narrow cavity of a flammable facade. Cavity fire is a multiphysics phenomenon, and all physics, i.e. fluid flow, heat transfer, buoyancy, combustion and pyrolysis involved in the model must be coupled step-by-step for a narrow cavity fire scenario to ensure model reliability. This thesis provides a step-by-step development of a CFD simulation for a narrow cavity fire. We split the facade cavity fire into six different scenarios with increasing complexity and validated the model against experimental data in the literature to limit the compensation effect. The compensation effect is the concept where similar results could be obtained by varying two or more parameters. We studied how cavity barriers affect fire dynamics and performed parametric studies to quantify the impact of both material properties and cavity width on fire dynamics inside a cavity of a flammable facade. This work demonstrates that modelling represents a powerful tool to aid in understanding facade cavity fire to improve building fire safety.Open Acces
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