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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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Defining success in decarbonising Scotland’s islands through the Carbon Neutral Islands Project
(Ricardo, 2026-05) Shaikh, Sabina; Voke, Ellie; Li, Helena; Hanbury, Katie; Morris , Simon
This project explores what the CNI project has achieved so far and investigates what is realistically achievable with a view to establishing a framework for measuring progress.
Modulation, tracking and adaptive system design for robust optical wireless communications
(2026-05-20) Chen, Jianhui; Popoola, Wasiu; Safari, Majid
Optical wireless communication (OWC) has emerged as a promising technology for high-speed wireless connectivity, offering vast unregulated bandwidth in the optical spectrum and inherent security advantages. However, the hostile nature of optical wireless channels, particularly in turbid, turbulent underwater and foggy free-space optical (FSO) environments, presents significant challenges for reliable data transmission. This thesis investigates the development of multiple complementary approaches to achieve link robustness in OWC systems, addressing challenges ranging from turbulence-induced fading and beam misalignment to time varying channel conditions through comprehensive theoretical analysis and experimental validation. Through experimental evaluation in a controlled channel emulator, an empirical investigation of frequency-based modulation schemes combined with polarisation division multiplexing (PDM) in underwater optical wireless communication (UOWC) channels is presented. The results demonstrate that frequency-shift keying with subcarrier intensity modulation (FSK-SIM) and frequency-shift chirp modulation (FSCM) provide inherent resilience to turbulence-induced received optical intensity fluctuations. In addition, the incorporation of PDM successfully approximately doubles the system throughput while maintaining the robustness of two frequencybased techniques. Building upon the need for link reliability, a fine tracking system for maintaining optical alignment in dynamic OWC links is developed. The system applies a photodiode array architecture with algorithm by differential intensity measurements to detect beam displacement in realtime. Experimental validation in free-space optical (FSO) channels demonstrates successful link maintenance at misalignment speeds up to 17.4 mm/s with 1.1% outage probability. Realtime image transmission experiments further validate the system’s practical impact, reducing bit error rate (BER) from 0.305 without tracking to 2.29 × 10−3 with tracking enabled. To simultaneously maximise data throughput and maintain link robustness under varying channel conditions, the investigation is expanded through the development of camera-based adaptive transmission strategies for both underwater and atmospheric channels. A k-nearest neighbour machine learning algorithm successfully classifies turbulence levels from captured images of backscattered light patterns with 99% accuracy, distinguishing between temperature-induced and bubble-induced turbulence. The system maintains reliable communication by dynamically adjusting modulation schemes based on the channel estimation, and achieves an average 3.51 Gbps throughout varying channel conditions. The adaptive OWC is further developed and demonstrated through a channel state information (CSI) estimation architecture based on corner-cube retroreflector. The system exploits deterministic polarisation changes induced by retroreflectors to enable transmitter side channel monitoring. The bidirectional propagation path effectively doubles the channel’s impact on the retroreflected signal, enhancing sensing sensitivity. Experimental validation demonstrates 9% throughput improvement in turbulent underwater channels and 15% improvement in foggy FSO channels compared to the best performing fixed modulation schemes.
Clustering of particles in weakly divergent flows
(The University of Edinburgh, 2026-05-20) Tully, Aidan; Vanneste, Jacques; Linkmann, Moritz; Cummins, Cathal
The clustering of particles in turbulent flows is an important mechanism in both natural and industrial processes. It appears across a diverse range of natural phenomena such as rain initiation and growth of rain drops, plankton dispersion in the ocean, and planetesimal formation as a result of aggregation of dust grains. In particular, turbulent particle laden flows in the ocean lead to the clustering of inorganic particulate matter, a topic of active interest with increasing concerns about microplastic and other particulate pollutants. Divergence in the particle velocity field is the cause of clustering of particles. The divergence is not necessarily a product of the compressibility of the carrier fluid and can occur from indirect causes. This thesis examines the clustering that results from two such indirect causes. The first is the inertia of particles, which makes the particle velocity differ from the fluid velocity and leads to clustering. We examine this process using the Maxey–Riley equation for inertial particle motion in the limit of small Stokes number St ≪ 1. In this limit, the dynamics in the full position–velocity phase space can be reduced to simple advection in position space, but with a new ‘effective’ velocity that is weakly divergent even though the fluid flow is incompressible. We study the statistics of clustering in this set up using a simple two-dimensional kinematic model in which the fluid velocity is random in time. The second indirect cause of divergence that is studied concerns particles floating at the surface of the ocean. These particles experience a two-dimensional divergent velocity field, namely the horizontal part of the full three-dimensional non-divergent fluid velocity. We model this horizontal flow using the SQG+1 model. This is an improved-accuracy version of the surface quasigeostrophic (SQG) model which captures the first-order corrections in the Rossby number (Ro) including the weak (horizontal) divergence. Particles in divergent flows converge to a fractal attractor in the position–velocity iii phase space. The projection of this attractor in physical space forms a fractal set. For floating particles, we make use of techniques from chaos theory to quantify the dimension of this set and consider in particular the information dimension D1 and correlation dimension D2. For D1, we rely on the Kaplan-Yorke conjecture which expresses D1 in terms of Lyapunov exponents. D2 is computed as a correlation sum. The dimension of the attractor is shown to scale quadratically in Ro for both estimates. For both inertial and floating particles, we examine in detail the rate of clustering as measured by large-deviations statistics of the particle density distribution. A Lagrangian approach is taken to overcome the challenge arising from the finite resolution of Eulerian models. We consider both the rate function describing the long time behaviour of this distribution and its Legendre dual, the free energy, describing the long time behaviour of the moments of the density. We develop and implement an importance sampling procedure to estimate the free energy accurately. This is necessary to capture the statistics of high moments of the density which are dominated by rare trajectories. We examine the applicability of the Kraichnan limit of short correlation time of the velocity for both inertial and floating particles. In this limit, we predict a parabolic shape for the free energy. The prediction is shown to be robust even when applied to experiments not strictly in the short correlation time limit.
Public perceptions of Carbon Capture and Storage
(Logika Group, 2026-05) Miu, Luciana; Wells, Rebecca; Hill, Dan; Grebot , Ben
A systematic literature review and interviewing 20 expert stakeholders finds that perceptions can change quickly and vary depending on the context. There is a persistent public belief that CCS is immature or unproven at scale, which can exacerbate public concerns. Safety is a key concern, particularly at local level. Other important concerns include fossil lock-in, cost, and local disruption. Early, tailored, and sustained communication from credible messengers is highlighted as vital for public confidence in CCS.
How can carbon pricing help achieve Scotland’s 2045 targets?
(Logika Group, 2026-05) Miu, Luciana; Umer, Huzefah; Hill, Dan; Sayers, Jamieleigh; Kulaga, Daryna; Tyrer , David
In Scotland, the buildings and transport sectors have not seen reductions in carbon emissions at the same rate as other sectors. Using the UK’s 7th carbon budget as a baseline, we model two carbon tax levels (£25/tCO₂ and £75/tCO₂) and two cap-and-trade system scenarios (with and without a soft price cap) in the period 2027 – 2045, with both partial and full cost passthrough to consumers. . The highest anticipated emissions reduction is in the higher £75 carbon tax scenario where costs are fully passed on to customers. The lowest emissions abatements were in the lower £25 carbon tax scenario, where costs are partially passed on. Our modelled ETS prices generate less emissions abatement than steadier price signals under a carbon tax. The model shows that most additional emissions reductions occur in the buildings sector. Costs are more significant for lower-income households. The disproportionate impact on low-income consumers can be alleviated through revenue recycling.