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In-situ control of magnetic multilayers studied with polarised neutron reflectometry
Get PDFPolarised Neutron Reflectometry (PNR) is a powerful measurement technique used for studying structural and magnetic profiles. Here, we develop the ability to perform PNR measurements with external stimuli applied in situ. These in situ measurement techniques provide new avenues of research for functional spintronic devices. The work of this thesis is split into two main studies. In the first, PNR measurements with in situ annealing are performed on C60/CoB/C60 trilayers to monitor the migration of B ions from the CoB magnetic alloy into C60 molecular layers. This allows for control of magnetism by changing the B composition of CoB. Initial SQUID magnetometry measurements allowed for a comparison of the magnetisation before and after annealing as well as the monitoring of the magnetic moment during annealing. The C60/CoB/C60 sample magnetisation increased by approximately 50% due to annealing. Structural information was gathered using PNR measurements with in situ annealing. The results show a significant injection of B into the C60 layers due to annealing. For a 10 hour anneal at 300◦C the atomic percentage of the CoB layer reduces by (7 ± 4)% resulting in an increase in the magnetic moment of (80 ± 30)%. Nuclear Reaction Analysis (NRA) measurements show a broadening of the B profile as further evidence of diffusion.
In the second main study of this thesis, an in situ FMR-PNR measurement technique is developed. This technique aims to combine the depth dependent magnetisation measurement of PNR with the measurement of magnetisation dynamics from FMR to unlock the ability to study the depth profile of the cone angle and damping. This measurement was performed in two geometries, one where the sample magnetisation and neutron polarisation are aligned and the other where there is an angle between the magnetisation and neutron polarisation. The second of these allows for a measurement of the magnetisation angle as well as the magnetisation. PNR measurements were performed with the sample on and off resonance to attempt to observe the changes in magnetisation due to the FMR precession. It was found that the measurement sensitivity is much greater for the magnetisation angle than the magnetisation magnitude so the angular sensitivity is vital for this measurement. Simulations were used to determine the relationship between the measured angle between the magnetisation and neutron polarisation and the FMR cone angle. These demonstrated that the change in the measured magnetisation angle from PNR is proportional to the square of the FMR cone angle, ΔθM ∝ ϕ2. The experimental measurements in this geometry show a small change in magnetisation angle of (0.2 ± 0.3)◦ corresponding to a cone angle of (3 ± 2)◦
Modelling the contact behaviour in the presence of viscoelasticity
Get PDFThis project addresses critical knowledge gaps in frictional viscoelastic contact mechanics, focusing on the partial slip phenomenon, where the contacting area is divided into stick and slip zones under insufficient tangential loads. The transient evolution of these zones and their influence on subsequent gross sliding behaviour remain underexplored for viscoelastic materials. To fill in these gaps, a numerical framework was developed, integrating time-dependent viscoelastic effects and coupling mechanisms arising from the frictional contact of dissimilar materials.
The research is structured around four objectives. As the foundation of the numerical framework, an elastic partial slip contact model was first developed to investigate effects of surface roughness on partial slip solutions. For rough contact of similar materials (nominally-flat against flat), the stick ratio is unaffected by roughness parameters but follows a linear relationship with applied tangential load. However, the relationship becomes nonlinear when dissimilar materials are involved due to the coupling effects.
The elastic models were then converted into transient viscoelastic partial slip contact models using the elastic-viscoelastic correspondence principle. Different from elastic materials, the separation pattern of stick and slip regions for viscoelastic materials varies with time when different phenomena (creep induced by a constant load or stress relaxation induced by a constant displacement) are encountered in lateral and normal directions, even though the stick ratio remains constant under constant contact inputs.
A transient viscoelastic sliding contact model was further developed to explore effects of early partial slip period on sliding contact solutions, including the delay of the attainment of steady-state sliding and slight decrease of the peak pressure compared to frictionless sliding. These findings justify the use of a frictionless assumption in viscoelastic sliding contact analysis, where qualitative predictions of steady-state behaviour are the primary research concern, such as the assessment of long-term tribofilm performance.
Finally, the framework was extended to model viscoelastic layered contact, focusing on zinc dialkyl dithiophosphate (ZDDP)-derived tribofilms. The layer-substrate system exhibits viscoelastic or elastic-dominated behaviour depending on loading and sliding conditions. In practical applications, the tribofilm performs primarily as a soft elastic layer. This study bridges nanoscale viscoelastic findings with large-scale observations, offering insights for optimizing additive performance in tribological systems
Enabling Better Healthy Food Recommendation By Incorporating Contextual Knowledge
Get PDFFood recommender systems (FRS) are increasingly recognised as valuable tools for simplifying food decision-making, while also promoting healthier eating habits. However, accurately predicting user preferences in this context remains a challenging task: choosing what to eat is a multifaceted and highly complex process. The greater challenge lies in recommending food that users will not only enjoy, but that is also healthy, requiring work that goes beyond the typical recommender system (RS) algorithms, which focus on maximising expected ratings and typically may encourage people to make less healthy choices.
This thesis seeks to improve food recommendation performance and address the taste-healthiness trade-off challenge and by integrating several forms of contextual knowledge, including situational context. Very little extant research has systematically explored the impact of multiple dynamic factors on influencing people's eating habits, recipe ratings, and nutritional intake behaviours. Most existing research focuses on single contextual factors, typically simple extrinsic ones such as location and time.
This research addresses these gaps by understanding daily eating habits through semi-structured interviews, followed by a large-scale experimental study in simulated contexts to examine how these contexts influence recipe rating behaviour and, therefore, implied nutritional intake. The results highlight the importance of developing context-aware recommender systems (CARS) leading to the development of novel one-stage and two-stage contextual modelling approaches with multimodal feature sets. An innovative method for generating healthy recommendations and a novel evaluation approach are also proposed.
Key findings suggest that dynamic contextual factors like emotions, busyness, seasons, and physical activities influence food choices and decision-making. People's preferences for healthy recipes vary with context, especially under stress. Incorporating such contextual features into RS algorithms significantly improves recipe rating predictions and permits healthier recommendations to be made. A contextual healthy recommendation approach and a novel evaluation metric, RMSEh, are introduced to align recommendations with individual preferences whilst promoting healthier choices.
This research has implications for the future development of FRS, and shows that emotion-aware systems could lead to better healthy food recommendations. These findings provide valuable insights into the design of more sophisticated healthy food recommender systems and offer a promising framework for the development of context-aware recommender systems across various application domains
Fitting into Fashion: Sizing, Bodies, and Modernity in Britain 1870–1930
No full textThis thesis explores an expanding market of middle-class women consumers’ experiences of fitting into the standardisation and sizing of the British fashion industry from 1870–1930. It addresses two interdependent gaps in fashion history: the evolving supply of fashionable ‘tailor-made’ production en masse and its physical, psychological, and socio-cultural demands on consumers—both of which continue to shape the fashion industry, body, and society. It asks: how did standardisation and sizing progress across the fashion lifecycle and (re)shape middle-class women’s bodily and embodied experiences of fitting into fashion? In answer, it draws on objects from across fashion’s supply chain and consumption—including manufacturers’ pattern cutting systems, retailers’ catalogues, and consumers’ wardrobes of altered garments—to show how each stage and stakeholder (re)fashioned industrial production and individual experiences of fitting in. These respective case studies (in)form distinctive methodologies: from reflections on remaking a disciplinary pattern; through multimodal analysis of catalogues’ sizing and body projects; to conservation-inspired reconstructions of everyday fashion-body biographies through altered garments in wardrobes. Collectively, these methods integrate approaches from creative practice, museums, and scholarship on the body, embodying theory through practice. This research reveals not only that the standardisation and sizing of women’s fashion considerably predates received histories, but also its flexibility, not fixity: manufacturers, retailers, and consumers all negotiated these new systems and their systematisation of the body. By exposing this complexity of fashion production and consumer experiences, this thesis reframes scholarly frameworks oversimplifying these processes. Altogether, this multimedia, multidimensional, and interdisciplinary study reveals previously concealed relationships between fashion, the body, and modernity. To disciplines concerned with these areas, it contributes newly object-led histories, methodologies, and theories that challenge ‘one-size-fits-all’ approaches and address fashion’s agency in shaping modern subjectivity. Beyond academia, it proposes new insights into bodily diversity in library, archive, and museum collections, and the legacy of a fashion history that structures contemporary industry cultures of size exclusivity
Uneven Grounds and Unequal Losses: Structural Disadvantage and Behavioural Biases in Well-Being
Get PDFThis thesis examines the roles of area-level deprivation and psychologically driven loss aversion in shaping subjective well-being. Drawing on data from the UK Household Longitudinal Study linked with the English Indices of Multiple Deprivation, the first empirical chapter demonstrates that living in a deprived neighbourhood systematically depresses life satisfaction — even for individuals with relatively higher incomes. Propensity score matching indicates this effect is not just a product of self-selection, suggesting that limited local resources or weak social structures exert an independent toll on well-being. Shifting focus from context to cognition, Chapter 3 uses the Household, Income and Labour Dynamics in Australia survey to examine how perceived income “losses” below a person’s permanent or typical baseline produce disproportionately larger drops in life satisfaction compared to equivalent gains. This asymmetry remains robust under varied definitions of permanent income and persists after controlling for key socioeconomic characteristics. Extending beyond finances, a discrete choice experiment in Chapter 4 shows similarly strong aversive responses in other domains, implying that negative deviations — whether in income, health, or autonomy — carry more weight than comparable positive changes. Together, these findings highlight that structural disadvantage and individual reference points can have substantial impacts on life satisfaction. Place-based inequalities constrain how far income alone can boost well-being, while loss aversion magnifies the damage caused by even modest downturns in key life spheres. Consequently, effective policy interventions may require both community-level improvements — better infrastructure, social services, and employment opportunities — and safeguards against sharp declines in individual income or health status. By uniting quasi-experimental methods with experimental approaches, the thesis underscores the critical interplay of local context and human psychology in determining well-being, offering a foundation for more holistic policy strategies aimed at enhancing life satisfaction and resilience
Acceptability of psychotherapy for Functional Neurological Symptom Disorder: A systematic review and meta-Analysis of psychotherapy refusal and dropout, and development of an ACT-informed self-help intervention
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Developing Alternatives to Vehicle EMC Testing
Get PDFElectromagnetic Compatibility (EMC) measurements are always a significant challenge especially in industrial contexts where reliability and repeatability are crucial. Standards like CISPR 25 (for component-level testing) and CISPR 12 (for vehicle-level testing) are commonly used in the automotive industry, but they often require large, expensive facilities such as anechoic chambers. A major issue arises when results from component-level testing fail to correlate with those from full vehicle-level tests, often leading to unexpected failures in compliance checks. This mismatch not only complicates development cycles but also results in considerable financial losses for the automotive sector.
In this thesis, this study focuses on radiated emissions testing with the goal of establishing a meaningful and practical correlation between component-level and vehicle-level measurements. To approach this, the research first develops a series of numerical models and scaled-down physical models (at a 1:10 scale), allowing us to simulate and test them in the University of York's EMC laboratory. These models are designed to mimic real-world setups but at a size manageable for the in-house equipment. Following this, full-scale measurements are carried out in industrial environments to validate the findings and ensure real-world relevance
Bird flight energetics and the mechanical performance of the muscles that power and control flight
No full textAlthough bird flight is the most energetically costly form of locomotion, it remains one of the most economical, allowing birds to cover relatively large distances and occupy a wide range of niches across all continents. This makes the study of flight energetics important for understanding bird behavioural ecology, especially for migratory species that must carefully manage metabolic energy expenditure during long journeys. According to aerodynamic theory, mechanical power output during flight follows a U-shaped relationship with flight speed. This power is predominantly generated by the pectoralis muscle, responsible for wing depression during the downstroke, while other muscles in the wing itself serve to control the shape of the wing, which is important in slow, manoeuvring, take-off, and landing flights. This thesis primarily examines the metabolic input and mechanical output of the main flight muscle during level, steady flight, and concludes with an exploration of the function of the scapulotriceps muscle, an intrinsic wing muscle, during various flight modes. Measurements of metabolic power using respirometry exhibited a U-shaped power-speed curve. The measurements of metabolic power were used to validate acceleration data measured using back-mounted accelerometers, as an indirect measure of energy expenditure. The findings suggest that accelerometry provides a proxy that can reliably estimate flight metabolic power during free flight. The strategies used to modulate pectoralis power output were assessed using in vivo recordings of muscle strain and activation patterns. These data were then replicated in a novel in situ work loop preparation to estimate force and power output directly, where no U-shaped relationship was found. Finally, the mechanical function of the scapulotriceps was investigated in situ, confirming its hypothesized role in elbow support during wing flexion. This work demonstrates that accelerometry can be utilized as a robust proxy for accurate estimation of metabolic power in the field and also provides the first in situ evaluation of the function of the scapulotriceps muscle across different flight modes
Identification Documents and the Governance of Mobilities in, through and beyond Seventeenth-Century London
Get PDFThis thesis examines the documentary processes used to identify people who were mobile into, out of, through and beyond seventeenth-century London. It develops the category of ‘identification documents’ to examine documents which were used by authorities to identify and thereby govern mobile people and their movements. This thesis examines these texts not merely as sources of information regarding seventeenth-century mobilities, but rather as functional documents produced and used by a variety of actors. Over the course of four chapters, this thesis examines how authorities in London used documents to surveil a broad range of patterns of movements: movements within England; movements from northwestern Europe to London; movements out of England to northwestern Europe; and movements out of London to English America. In doing so, this thesis demonstrates that the seventeenth century witnessed the development of a variety of different forms of document which were used to monitor and control a wide range of mobilities.
In the seventeenth century, the identification of mobile people developed as a key logic and mechanism of governance deployed by a variety of different authorities in London in their efforts to govern movement and mobile people. This logic of governance was fundamentally structured by patriarchy. These processes of identification developed into a central aspect of how mobile people interacted with authorities in seventeenth-century London. These interactions were crucially shaped by gender and thus led to important gendered divergences in how men and women experienced both migration and authority. This thesis demonstrates that the development of processes in which authorities monitor and control movement, including transnational movement, is not a recent phenomenon, but rather developed in early modernity as a product of the relationship between heightened levels of mobility and authorities’ efforts to govern and surveil these mobilities by producing, using and storing documents
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