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ERA is a digital repository of original research produced at The University of Edinburgh. The archive contains documents written by, or affiliated with, academic authors, or units, based at Edinburgh that have sufficient quality to be collected and preserved by the Library, but which are not controlled by commercial publishers. Holdings include full-text digital doctoral theses, masters dissertations, project reports, briefing papers and out-of-print materials.

Information on current research activity including staff, projects and publications is available via the Edinburgh Research Explorer.

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Recent Submissions

Ferrofluid-gaps for direct-drive wind turbine generators
(2026-05-15) Hall, Fergus; McDonald, Alasdair; Mueller, Markus; Engineering and Physical Sciences Research Council (EPSRC); EPSRC Wind and Marine Energy Systems and Structures Centre for Doctoral Training (CDT WAMSS)
The commercial offering of offshore wind turbines has generally converged upon three-blade horizontal-axis designs with variable speed generators and pitch-regulated blades. Arguably, the most significant distinguishing feature is whether the powertrain has a direct-drive or geared configuration. In a direct-drive powertrain, there is no gearbox that steps up the rotational speed and steps down the torque from the turbine rotor for input into the generator. This low-speed and high-power operation necessitates the production of immense electromagnetic torque: on the order of 20 MNm for a 15 MW wind turbine. As a result, direct-drive wind turbine generators are large, heavy, and require a substantial amount of rare earth permanent magnet material in their construction: on the order of 20 tonnes for a 15 MW wind turbine. Rare earth permanent magnets are expensive and environmentally damaging to procure, designers typically attempt to make the air-gap clearance of direct-drive wind turbine generators as small as practicably possible so that the air-gap magnetic reluctance is minimised: reducing the amount of permanent magnet material required. This thesis investigates an unconventional approach to reducing the permanent magnet material requirements of direct-drive wind turbine generators in which the air-gap region is flooded with magnetically permeable ferrofluid such that it becomes a ‘ferrofluid-gap’. The initial chapters of this thesis examine the design of multi-megawatt scale direct-drive wind turbine generators. A detailed design procedure is specified which is supported by an advanced thermal modelling methodology. A review of air-gap dimensioning is provided, and insights are presented that improve understanding in this area. Subsequent chapters focus on the ferrofluid-gap concept. First, it is explained how the magnetic and mechanical behaviour of ferrofluid-gaps can be modelled according to theoretical predictions. Prior work regarding the ferrofluid-gap concept is reviewed and the opportunities for further research are highlighted. To validate the theoretical models of ferrofluid-gap magnetic and mechanical behaviour, a novel ferrofluid-gap test rig was designed, fabricated, and tested. The test rig dimensions were scaled such that the fluid dynamic conditions expected in multi-megawatt scale direct-drive wind turbine generators could be achieved at a laboratory scale. The resulting experimental data provides unprecedented validation of the theoretically predicted magnetic and mechanical behaviour of ferrofluid-gaps in radial-flux electrical machines. Drawing upon the analytical models, design tools, and experimental results developed throughout this work, the feasibility of ferrofluid-gaps for direct-drive wind turbine generators is assessed. It is found that, in principle, ferrofluid-gaps can enable a reduction in permanent magnet material (~10%) without unacceptably compromising efficiency due to drag losses. It is also demonstrated that a ferrofluid-gap has the potential to enhance thermal performance. However, it can be concluded that the potential benefits of a ferrofluid-gap are outweighed by the costs and difficulties associated with their implementation in multi-megawatt scale direct-drive wind turbine generators.
Tuneable multilevel capacitance switching in hafnium-based oxides
(2026-05-15) Yadav, Deepika; Prodromakis, Themis; Stathopoulos, Spyros; Cheung, Rebecca
Memcapacitors are devices exhibiting history-dependent capacitance in response to applied electrical stimuli and have attracted increasing attention as potential building blocks for adaptive, reconfigurable, and energy-efficient electronic systems. Unlike conventional tunable capacitors that rely on continuous biasing or mechanical actuation, memcapacitors offer non-volatile capacitance tuning, enabling circuits that retain their programmed functionality without static power consumption. However, practical implementations that are compact, CMOS-compatible, and capable of reliable multilevel operation remain limited. This thesis therefore investigates memcapacitive behaviour in metal–dielectric–metal device architectures. Hafnium oxide is chosen as the dielectric material due to it’s high dielectric constant, ultrathin scalability, and CMOS compatibility, while appropriate compositional modification also enabling ferroelectric behaviour. These versatile properties allow hafnium oxide to be explored across two distinct physical regimes: defect-mediated switching in conventional hafnium oxide and polarisation-driven switching in ferroelectric hafnium zirconium oxide (HZO). This provides a unified framework to study the evolution of memcapacitive behaviour from binary to multilevel operation. In the first part of the thesis, memcapacitive behaviour is examined in conventional hafnium oxide memristor. Although primarily investigated for resistive switching, the geometry is inherently capacitive, offering an opportunity to study capacitance modulation. Electrical characterisation reveals binary capacitance switching with a capacitance ratio of 1:3 and a memory window of ∼3 pF in a 20×20 μm2 device, programmed using voltage pulses up to 5 V. Scaling the device area increases the absolute capacitance and enhances the capacitive ratio, confirming that the modulation scales with device geometry. Finally, an equivalent circuit model is developed to quantitatively capture the coupled resistive–capacitive behaviour. Building on this binary baseline, the thesis then investigates ferroelectric HZO capacitors, where capacitance is controlled by switchable polarisation rather than defect dynamics. These devices exhibit a substantially enlarged non-volatile capacitance window of approximately 24 pF and enable access to more than eight stable capacitance states, with endurance ∼10^6 cycles and retention beyond 10^5 s. The states are well separated, with switching behaviour analogous to potentiation–depression, and can be programmed using voltages within ±3 V for a 60 × 60 μm2 device size. Area-scaling analysis reveals a progressive reduction of the capacitive memory window with decreasing device size. At 20 × 20 μm2, the memory window becomes comparable to that observed in memristive devices, while voltage-dependent analogue switching remains intact. In this context, a single reconfigurable ferroelectric device can deliver capacitance densities of approximately 27 fF/μm2, which are competitive with current MIM technologies, while simultaneously providing non-volatile and programmable capacitance states. This combination offers a pathway to reduce overall capacitor footprint by replacing multiple fixed-value elements with a single tunable memcapacitor. Further studies of frequency-dependent be- haviour, dielectric loss, and DC leakage establish the operational limits and practical constraints governing reliable multistate performance. To verify circuit-level integration, the HZO devices were employed in a tunable high-pass filter and a relaxation RC oscillator. The filter cut-off frequency was tuned by 4.4 kHz, while the oscillator frequency was tuned by 6.5 kHz, directly translating non-volatile capacitance states into programmable frequency responses. In addition, complementary electrostatic force microscopy measurements confirm local charge and polarisation modulation, providing microscale evidence of stable multistate capacitive behaviour. Overall, this thesis presents a comprehensive progression of memcapacitive behaviour in hafnium-based devices, from binary defect-mediated switching to multilevel ferroelectric operation, supported by electrical, microscopic, and circuit-level analyses. The results establish hafnium-based ferroelectric capacitors as a scalable and versatile platform for non-volatile analogue capacitance tuning, with relevance to reconfigurable electronics, adaptive analogue systems, and emerging memory-centric computing architectures.
Moduli space of parahoric Higgs bundles
(The University of Edinburgh, 2026-05-15) Réga, Karim; Martens, Johan; Davison, Ben
We study parahoric Higgs bundles over a smooth, projective curve. We start out by reviewing the notion of a parahoric group over a local field and associated group schemes constructed by Bruhat and Tits. We continue by reviewing recent criteria to prove the existence of good moduli spaces for an algebraic stack by Alper, Halpern-Leistner and Heinloth. The first result is an application of these criteria to anti-invariant Higgs bundles, which provide a specific example of parahoric Higgs bundles. Lastly, we review work on the moduli of gauged maps by Halpern- Leistner and Herrero and show how this can be used to prove the existence of a moduli space for parahoric Higgs bundles.
Prenatal SMN-dependent defects in translation uncover reversible primary cilia phenotypes in a mouse model of spinal muscular atrophy
(2026-05-15) Genovese, Federica; Gillingwater, Tom; Huang, Nikky; Faller, Kiterie
Spinal muscular atrophy (SMA) is a rare inherited neuromuscular disease with an incidence of around one in every 10,000 live births. In most patients, SMA is caused by mutations in the survival motor neuron 1 gene (SMN1), resulting in insufficient production of full-length, functional SMN protein. The SMN protein is dynamically regulated during development, where high levels of SMN expression during embryogenesis undergo a significant reduction after birth, suggesting an important role for SMN prenatally. SMN has also been shown to be a ribosome-associated protein that plays a crucial role in translation and ribosome biology. Therefore, when SMN is depleted, widespread perturbations of protein synthesis occur in SMA. Several therapeutic approaches aimed at boosting SMN are now approved for use in human patients, leading to significant improvements in lifespan and symptom severity. However, new and unexpected phenotypes are being reported in treated SMA patients, including significant neurodevelopmental alterations in some individuals, indicative of changes in brain development. In this thesis, I use a mouse model of severe SMA to explore the prenatal development of the central nervous system (CNS). Using a combination of morphological and molecular analyses, I reveal neurodevelopmental defects in SMA embryos and demonstrate that these changes are accompanied by widespread perturbations in translation. Furthermore, by performing network analysis of the genes presenting with alterations in ribosome occupancy, I show the involvement in processes related to primary cilia. Assessments of primary cilia in the CNS in vivo and in primary neuronal cultures in vitro confirmed the presence of a primary cilia phenotype in SMA. Finally, to demonstrate that this observed novel phenotype is SMN-dependent, and amenable to therapeutic intervention, in this work I show that prenatal transplacental treatment with risdiplam, an approved SMN-restoring drug, can rescue primary cilia defects in SMA mouse embryos. Using these approaches, I unveil that SMN protein is necessary for the normal cellular and molecular development of primary cilia in the CNS, and that prenatal treatment with SMN-restoring therapies can address neurodevelopmental phenotypes in SMA.
Isa Town and the modernisation of Bahrain
(The University of Edinburgh. College of Humanities and Social Sciences, 2026-05-15) Al Khalifa, Hesa Khalifa Ahmed; Freeman, Richard; Williams, Richard
As a modern phenomenon, the new town spread from the UK to Europe and eventually the rest of the world. New Towns gained widespread attention for their reconfiguration of new social orders and their construction of new spatial domains. They came in all forms and sizes – each was similar enough to be recognised as a new town, and yet each one contained varying iterations and characteristics. For countries in the Arabian Gulf, new towns were born out of the oil boom and were sustained by a political determination that has capitalised on their value to illustrate new visions of urbanisation, build economies, and mobilise societies living within them. They continue to be a part of political, economic, and social realities, set in narratives of the past as well as urban development plans. Unlike in other countries where they were introduced, such as the UK, their popularity in the Arab world did not wane or diminish. Thus, they remain as relevant today as when they were first introduced there in the second half of the twentieth century. One of the earliest examples in the Arabian Gulf, Bahrain’s Isa Town, which was built in multiple phases between the early 1960s and the early 1980s in Bahrain, illustrates the evolution of a new relationship between social, economic, and political processes in an evolving state. Until now, however, it has largely been absent from the wider and regional literature on new towns. Originally part of a state vision based on modernisation, Isa Town was designed and supervised by the British company George Wimpey, Ltd., and built by a group of up-and-coming local construction firms. The first of its multiple phases occurred between 1963 and 1974, when the Bahraini state oversaw the building of a whole new town with multiple house typologies for low to middle-income Bahraini families. The original town was also designed to include a wide spectrum of social and cultural amenities such as schools, health clinics, a town centre, a stadium, and other mixed-use facilities, transforming them into the centre of political and social attention in Bahrain and beyond. This thesis aims to bridge the knowledge gap regarding new town examples outside the West, particularly in the Arabian Gulf. It builds on several key local Bahraini and external archives, using multimodal data in the form of photographic images, cinematographic recordings, and oral history interviews, to make up for silences within archives and address power relations within and across them. The project studies Isa Town and examines why it was built and its meaning to its community and the Bahraini society more broadly. Notably, it was through this state-led housing project that the Bahraini government developed and illustrated its new administrative capacity as it was preparing to embrace sovereign independence, simultaneously transforming society from the inside out. Isa Town was the process in which modernisation was mainstreamed to low- and middle-income Bahraini families, and it served social and political aims, in place of constitutional innovation. More specifically, Isa Town socially transformed Bahraini families and modernised an evolving public administration body while supporting both with extensive contemporary media coverage. This Isa Town study illustrates the transformative nature of the move from older towns and villages for those who came to live there and what the new town represented for the Bahraini state. It also highlights how the new town was a space for both the state and citizens to construct and project their new modern identity, both of which were mediatised through a comprehensive creation and circulation of images to both local and foreign audiences, as seen in photographic images and newsreel creations found within the Bahrain Oil Company archives, their publications and elsewhere. In short, Bahrain’s first new town illustrates the execution of a national modernisation project at a critical time in its modern history. Due to the continuing interest in new towns in the Arab world and elsewhere, studies of their emergence and creation are as relevant today as they were when they were first introduced. The study of Isa Town sheds light on several important social, political, and administrative considerations regarding new towns and their development, offering critical knowledge for the future of these communities.