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Intelligent State Evaluation and Fault Diagnosis Methods for Wind Turbines
No full textWind power is an important green and sustainable source of power generation. However, the construction of wind farms needs a large amount of initial investment and a highly expensive maintenance cost for wind turbines (WTs). Therefore, it is crucially important to accurately assess the state of WTs and keep WTs in good operation conditions. This thesis proposes a framework for the novel intelligent state evaluation and maintenance arrangement (iSEMA) system based on digital twin (DT) and deep learning (DL) technology, which can accurately evaluate the state of WTs and detect faults in the early stage. With the proposed iSEMA system, operators can better monitor WT conditions and use the information provided by the iSEMA system to schedule maintenance work more effectively, thereby minimizing downtime and boosting the economic efficiency of WTs.
In addition, this thesis creatively gives the concept of the sub-healthy state of WTs by introducing some relevant quantities, which is very useful for designing the iSEMA system and better describing the state of WTs. Based on the historical data of WTs, the iSEMA system can automatically select the suitable value of the parameters.
In the research about bearing fault diagnosis methods, this thesis proposed a novel hybrid framework by combining traditional machine learning (ML) and advanced DL models. The proposed hybrid framework can not only realize the automatic feature extraction for random forest (RF), but also significantly improve the accuracy for handling multi-classification problems.
Based on the auxiliary classifier generative adversarial networks (ACGANs) which is an advanced variant of the generative adversarial network (GAN), this thesis proposed an improved bearing fault diagnosis method for handling the imbalanced data problem. This method addresses the issue of insufficient fault data in real-world scenarios, which leads to low accuracy of data-driven methods in fault diagnosis
Enriching Electronic Health Records with Semantic Features: Leveraging Multi-Modality Embeddings.
No full textThe exponential growth of Electronic Health Records (EHRs) offers rich clinical narratives for
healthcare improvement, but their unstructured nature makes information retrieval challenging.
While models like BERT excel in classification tasks, their potential for EHR-based retrieval—
especially in combining structured and unstructured data—remains underutilized.
We introduce ClinicalNarr, a transformer-based model for clinical information retrieval. Our
initial research examined four language representation settings, finding that concept-only em-
beddings achieve superior performance (BERTScore F1: 0.699) by emphasizing key medical
concepts while filtering noise. Building on these insights, ClinicalNarr leverages MIMIC-III
data, combining structured ICD codes with unstructured narratives to improve retrieval. When
tested on MedNLI, it achieved 90.5% accuracy, outperforming previous models, with strong cor-
relations with physician judgments (r=0.69) and medical coders (r=0.76).
Comparative analysis reveals HNSW’s superiority over IVF for semantic retrieval (NDCG@10:
0.49 vs. 0.43). ClinicalNarr outperformed existing models, achieving three times better hit
rate. This advantage expanded with our novel ontology-augmented evaluation methodology,
which increased performance by 13%—reaching a 52% Hit Rate compared to competing models
(15-20%).
This study establishes a benchmark for clinical information retrieval using MIMIC-III, sig-
nificantly advancing clinical decision support capabilities by improving semantic alignment in
healthcare information system
Development of bifunctional, carbon-supported nanocatalysts for wastewater treatment
Get PDFGlobally 1 in 3 people do not have access to safe drinking water. [1] Households, industry, and agriculture often introduce persistent organic pollutants into their waste streams, and by extension into surface waters, ground water and eventually drinking water supplies.[2] An increasing number of these pollutants are being linked to potentially serious negative health effects.[3-4] The ideal solution to this problem would be to prevent these compounds from reaching surface waters, but failing that, there is a pressing need for sustainable, highly active tertiary water treatment solutions.
The most common experimental tertiary water treatment methods use coagulation flocculation, adsorption on activated carbon materials, ozonation, advanced oxidation processes (AOPs), and various bioremediation processes.[5] Some of these methods do not actually destroy pollutants, just transfer or concentrate them into another phase, which often ends up being incinerated, while others suffer from high costs and/or slow detoxification.
This thesis discusses the development of carbon-supported bifunctional catalysts that are capable of both generating H2O2 and decomposing it into reactive oxygen species, which can then be used to efficiently degrade aqueous organics.
The first chapter of this thesis explores the emergent synergism between a macroscale carbon, graphitic nanofibres (GNFs), and a Fenton like catalyst (MnO2). Extensive characterisation is used to uncover the structure-performance relationships governing the activity of this composite catalyst. A novel metric is also suggested for the field of organics removal, which separates out the different contributions to overall organics removal. This research has shown that the most active MnO2-GNF composite facilitates more than three times as much truly catalytic dye degradation than unsupported MnO2. The ability of the composite to dissipate heat has been identified as a crucial factor in this increased catalytic activity.
The second chapter explores the chemical modification of two macroscale carbon materials, GNF and carbon beads (CB), via acid oxidation, and the effect of this modification on sorption characteristics. Observations show that GNF was mostly unchanged by acid oxidation, but CB went through significant changes. In this case, overall surface area decreased moderately but the ratio of micropore area to overall surface area increased, while the concentration of acidic surface functional groups doubled. This led to a strong suppression in the mostly irreversible adsorption of the studied organics.
These acid oxidised carbon materials (oGNF and oCB) are then used as catalyst supports in Chapter 3. In this chapter the synthesis and thorough characterisation of Co, Mn spinels is discussed, along with the catalytic performance of composites made of the most active spinel, and GNF, oGNF, CB and oCB. It was found that the formation of composites only led to an enhanced catalytic performance in the case of Co2MnO4-oCB, compared to the unsupported catalyst. Results also show that oCB composites facilitate a much higher truly catalytic activity, partly because of the prevention of adsorption.
Finally, in Chapter 4 the electrocatalytic activity of the previously synthesised composites are investigated in O2 reduction. The electrochemical activity of GNF and oGNF supported Co, Mn spinels has been investigated with multiple electroanalytical methods. Results showed negligible O2 reduction activity in the case of all studied materials.
This research highlights the suitability of macroscale carbon materials as catalyst supports in Fenton-like chemistry, while also emphasises the need for a nuanced approach to catalytic activity in the field, as not all organics removal modes are equally desirable. Additionally, the results discussed here show that the acid oxidation of macroscale carbon supports is a viable way of enhancing the catalytic activity of composites made with such materials
Demystifying the arts centre model: a critical exploration of a difficult difficult brand
Get PDFDespite their prevalence in both England and Australia, arts centres are often
neglected within academic research and policy. Beyond a few surveys and a
handful of publications, there is little investigation into the arts centre model
internationally and specifically in England and Australia. This thesis aims to
demystify the arts centre model, shedding light on arts centres in both England
and Australia by asking the question: How suitable is the arts centre model for
effective arts and cultural provision? To undertake this task, this thesis
incorporates three methodological approaches: an online survey with 201 arts
centres, nine external expert interviews, and four arts centre case studies.
The findings highlight the centrality of an arts centre’s relationship with its
community and provide insight into the role of arts centres, uncovering the
unique characteristics of arts centres in terms of management and leadership,
programming, marketing and branding, and stakeholder perceptions. The
research suggests that these inherent characteristics of the arts centre model
could be viewed as providing unique opportunities, yet also constituting a difficult
difficult brand (Harrison and Hartley, 2007), as it is precisely the characteristics
that make arts centres unique that present them with their greatest challenges.
This research reveals that the use of broader literature in the arts centre setting
fails to consider the complexities and nuances of the arts centre model. This
research is particularly timely given the opportunities presented by arts centres in
supporting policy agendas such as the focus on the hyperlocal (Polivtseva, 2020;
Sargent, 2021; Walmsley et al., 2022), placemaking and the rise of local and
regional policymaking. My research shows that if managed appropriately with
community at its heart, arts centres are an untapped resource for communities,
worthy of further research and attention
Plasma-Enhanced Pulsed Laser Deposition of metal oxynitride thin films for photoelectrochemical water splitting
Get PDFPlasma-enhanced pulsed laser deposition (PE-PLD) is a novel thin film deposition method
which employs radio-frequency plasmas and laser-ablated plasma plumes to produce semiconductor thin films. A high-powered, pulsed laser ablates material from a metal target into a plasma plume, which interacts with non-metal inductively-coupled plasma species to form metal compound material that deposits onto a substrate. PE-PLD has been shown to produce high-quality metal oxide thin films with many applications, including photocatalysts which use solar energy to produce hydrogen fuel from water splitting. PE-PLD remains an active area of research, particularly elucidating its underlying plasma physics and chemistry, such that thin films can be created according to specific criteria rather than empirical observation. This work centres around the suitability of PE-PLD in producing metal oxynitride thin films for photocatalysis.
This thesis presents results from modelling the laser ablation of different photocatalytic
metals using the code POLLUX, showing the electron temperature and mass density of the plasma plume both increased with the atomic number of the material, whilst the mass density of the material had no observed effect on the electron temperature or particle density of the plume.
Additionally, the TALIF diagnostic provided absolute measurements of ground-state
atomic O and N densities for a range of low-pressure oxygen/nitrogen plasma mixtures, showing the relative flow input of oxygen and nitrogen had the greatest control over the O:N atomic density ratio, allowing it to change by up to a factor of 100.
Finally, the structure and chemical composition of deposited metal oxynitride thin films
were analysed with different diagnostics, showing a consistent lack of nitrogen present on the films and lack of visible light absorption, highlighting many areas of improvement for PE-PLD in producing oxynitride films, such as understanding interactions between oxygen/nitrogen plasma species and their effect on deposition
Creative accounting and corporate social responsibility
No full textAbstract
The literature has extensively examined creative accounting and corporate social responsibility (CSR). However, there is limited evidence on the interaction between voluntary activities, such as CSR, and accounting practices. This study investigates the association between creative accounting and CSR.
A mixed-methods approach was employed, integrating both qualitative and quantitative methods—an underutilised research design in this area. This approach provides a more comprehensive perspective compared to single-method studies. The qualitative component, based on interviews, offers new insights into the relationship between creative accounting and CSR that may not be easily captured through quantitative analysis. In contrast, the quantitative analysis tests the relationship between key variables using secondary data.
The qualitative research involved interviews with eleven chief financial executives from UK-listed companies in the FTSE 350 index and six auditors from the "Big Four" accounting firms in the UK. The quantitative data was collected from DataStream, Thomson Reuters Asset 4, and Bloomberg, covering non-financial UK firms listed in the FTSE 350 index from 2010 to 2019.
The findings from both methods reveal that UK companies are willing to reduce CSR spending as a tool to achieve financial objectives. Additionally, the study identifies a bidirectional relationship between creative accounting and CSR performance, driven by corporate principles and values. Similarly, a negative relationship is found between creative accounting and CSR disclosure. However, firms are more likely to engage in impression management through CSR disclosures in meetings, which appears to be more effective than relying solely on CSR information presented in annual reports
Advancing the Development and Integration of Dynamic-Bodied Ionic Solution-Based Soft Sensors for Biomedical Robots
No full textMedical robots are increasingly adopting soft robotic technologies, to minimise the damage left behind by robotic interventions and explore new therapeutic treatments. For long-term implantable robots interacting with tissue, there are a plethora of challenges presented by the in vivo context, including biocompatibility, safety and compactness of design. Soft robots afford many advantages and answers to these contextual requirements, including their inherent compliance and hyperelasticity, providing the means for both increased safety, as well as generating large expansions from compact designs. However, the use of soft robots is limited by their infinite degrees of freedom, state-dependent and nonlinear behaviours, a strong dependence on the external environment, and difficulties in differentiating between stimuli. Soft sensors capable of giving information on the system and environment as a whole, as well as any abnormalities and faults, and, importantly, able to adapt to the changes in both the robot and the environment, will be key in driving, and securing, the future of soft technologies in medical robots.
In this thesis, a variety of sensing technologies are implemented and explored to advance the development of safer and more effective medical robots. Firstly, a soft sensor actuator, capable of large expansion and differentiating between height and pressure, is introduced as a building block for a variety of demonstrated probe and implant applications. Pressure and resistance sensing were shown to be interchangeable, although best used in combination, and a best estimated resolution of 4 g and 0.07 mm was achieved. The integration of these sensing technologies to distinguish between internal and external stimuli is developed further in the context of tissue lengthening soft robots. A three-columned sensor-actuator is shown to have good structural strength, shrinking by only 12 % under a 500 g load and growing more than 80 % of its unloaded height when preloaded with 250 g. The resistance sensing also proved useful for bending characterisation, but further work is still needed to improve repeatability. Finally, new methodologies, to maximise the information of localisation of stimuli and to tune the sensors to a robot and its context, are presented. The ability to tailor and tune sensing is preliminarily demonstrated as an opportunity to adjust sensing dynamically to the context. Additionally, exploiting the dynamics of fluid-based sensing is shown, allowing single and multiple press events and their locations to be determined
Characterising the Emission and Dispersion of Aerosols from the Toilet Plume and Quantification of the Associated Infection Risk
Get PDFToilet flushing is known to generate aerosol plumes that can contain pathogenic microorganisms, and shared toilet facilities have been implicated in the transmission of infectious diseases. However, few studies have quantified the infection risks posed by these aerosols or investigated in detail how they disperse after flushing.
This thesis presents an integrated analysis of airborne infection risks associated with toilet plume aerosols, combining controlled experimental studies, quantitative microbial risk assessment (QMRA), and computational fluid dynamics (CFD) simulations. The aim is to investigate aerosol generation, dispersion, and mitigation strategies in shared toilet settings.
Controlled chamber experiments were conducted using a gravity-flow, close-coupled toilet, with and without a cubicle enclosure over a range of ventilation rates. The generation of aerosols was characterised by flushing a salt solution, revealing a large proportion of smaller particles (< 5 μm). Particle concentrations peaked in the first 1 min after flushing and returned to background levels within 10 min. Bioaerosol sampling using Escherichia coli showed that most bacteria were released in the first 5 min after flushing, with ventilation rates having a modest influence on airborne concentrations. Continuous but low-level bacterial deposition suggested cumulative risks from surface contamination.
A QMRA framework was developed to assess the infection risks associated with single flushing events, accounting for transient aerosol dynamics and realistic occupancy durations. Two models were developed: one combining particle concentrations with estimated viral loads, and another using measured bioaerosol data. When applied to the experimental results, these models suggested non-negligible infection risks, particularly for pathogens present at high faecal concentrations, such as norovirus. The introduction of short delays (> 1 min) between toilet users significantly reduced the estimated infection risks.
CFD simulations further examined aerosol dispersion and exposure risks, demonstrating how room layout, ventilation rate, and outlet positioning influence aerosol removal. Optimised ventilation strategies, including increased airflow and repositioned outlets, substantially reduced airborne particle concentrations.
This research provides new insights and robust methods to evaluate and mitigate airborne infection risks from toilet plume aerosols, with implications for public health guidance and the design of safer shared toilet environments
De-implementation of low-value practices (clinical and non-clinical) in UK mental health services: A patient perspective
Get PDFBackground: Low-value care is a widely recognised issue that threatens the quality of patient care and the sustainability of healthcare systems. The majority of efforts to identify and stop the use of low-value care have focused on clinical practices such as unnecessary diagnostic tests, clinical treatments and surgical procedures. Little is known about non-clinical patient safety practices. Furthermore, there appear to be limited efforts to identify and de-implement low-value care in mental health services. Eliminating practices that are wasteful could free up the time and resources staff need to provide safe and high-quality care.
Aims: The overall aim of this PhD to identify low-value care practices in UK mental health services, examine how they could be de-implemented and understand the role of patients in this process.
Study 1: A systematic review and meta-analysis were conducted to examine the effectiveness of de-implementation interventions that target patients. The ‘active ingredients’ in successful interventions were also explored. The review highlighted the importance of the patient-clinician interaction in stopping low-value care and the paucity of de-implementation efforts in mental health settings.
Study 2: To identify mental health care practices that are perceived to be low-value, semi-structured interviews were carried out with people who have lived experience of mental health challenges. Four practices were identified as low-value. This included the overuse of antidepressants, risk assessments, physical restraint and enhanced observations.
Study 3: An established de-implementation framework was used to determine a priority practice for further exploration. The literature surrounding each practice was reviewed to explore existing efforts to de-implement these practices. Through this process, enhanced observation on mental health wards was identified as a potential target for de-implementation.
Study 5: To explore enhanced observations further, a rapid ethnographic study was carried out at three NHS acute female mental health wards. This study looked at how enhanced observations were experienced by staff and service users, how they are conducted, and how ward related cultural and contextual factors impact the use of this practice. Contextual summaries of each site and crosscutting themes were developed to summarise interviews and observational data.
Study 6: The final stage of this PhD involved developing recommendations to reduce the inappropriate use of enhanced observations. A four-stage stakeholder consultation process was used to refine a set of nine recommendations.
Conclusion: Study findings presented several novel insights about low-value mental healthcare practices. Evidence from this PhD provides a novel way of involving service users in the identification of low-value care and de-implementation. The findings also contribute to the development of de-implementation theory and understanding the patient's role in de-implementation
The site-specific kinetics of OH radicals with esters
Get PDFThis work uses laser flash photolysis coupled with laser induced fluorescence to experimentally determine the overall and site-specific kinetics of a series of formates. The total kinetics for OH and OD + methyl formate and its deuterated isotopomers (CH3OC(O)H, CH3OC(O)D, CD3OC(O)H and CD3OC(O)D) have been determined between 298 and 573 K and are outlined in Chapter 3. The kinetics of OH + methyl formate determined in this work are in excellent agreement with literature studies at 298 K and bridge the gap between the work of Le Calve et al. (253 – 372 K) and Lam et al. (876 – 1371 K). The KIE indicates similar branching ratios from both the methyl and formate reaction sites, which are determined to be coupled, with a coupling factor of 2.38 at 298 K.
The experimental site-specific kinetics of OH + methyl formate (CH3OC(O)H) and CH3OC(O)D are outlined in Chapter 4. The rates of thermal decomposition of the CH3OC(O) radical formed following formate abstraction have also been determined, and decomposition is demonstrated to dominate over oxygen addition above ~ 423 K. The rate coePicients for CH3OC(O) + O2 and CH2OC(O)H + O2 are investigated in the low-pressure regime between 8 and 84 Torr, and 298 and 573 K. Experiments indicate the ether-centred radicals react with oxygen faster than carbonyl-centred radicals, in agreement with literature trends. The site-specific kinetics for hydrogen abstraction reactions of the OH radical with methyl formate are determined from Stern-Volmer intercepts, utilising the decomposition of CH3OC(O) to determine the branching ratio for methyl abstraction. The site-specific kinetics are also determined from the internal isomerisation of thermalised RO2 radicals, which form a carbon-centred radical (QOOH) that promptly decomposes to regenerate OH. There is good agreement between the OH yields determined from both methods. The experimental site-specific kinetics are also compared with MESMER calculated rate coePicients determined by Dr Robin Shannon.
Chapter 5 outlines the overall and site-specific kinetics of isopropyl formate. This work demonstrates that the current temperature-dependent kinetics of OH radicals with isopropyl formate by Zhang et al. likely underestimate the overall rate coefficient due to interference from OH regeneration. At 298 K, the site-specific kinetics for formate abstraction have been determined in good agreement with Pimentel et al. Above 400 K, decomposition of the (CH3)2CHOC(O) radical prevents OH regeneration following formate abstraction. Thanks to ab initio calculations at the M062X/6-31+G** level of theory, OH regeneration above 400 K is attributed to tertiary abstraction, providing the site-specific kinetics for tertiary abstraction by OH radicals between 400 and 573 K. The ab initio calculations also indicate the acceleration in the overall rate coefficient below room temperature is due to tertiary abstraction, which has a negative energy barrier. Above approximately 400 K, abstraction at the tertiary site is experimentally determined to decrease, coinciding with an increase in the rate coefficient, largely attributed to increasing formate abstraction.
The experimental site-specific kinetics of methyl formate (Chapters 3 and 4), isopropyl formate (Chapter 5), ethyl formate (determined by Dr Lavinia Onel, Appendix E), tertbutyl formate (Appendix E) and n-butyl formate (Appendix E) are combined in Chapter 6 and discussed in terms of wider trends in ester reactivity. The coupling between reaction sites in methyl formate is also demonstrated for the other formates and higher esters. Experimental site-specific kinetics are implemented into an updated structure activity relationship (SAR). The overall and site-specific kinetics of n-butyl formate are reserved from SAR development and used to test the updated SAR. The updated SAR improves upon the current SAR prediction of overall and site-specific ester kinetics. Consequently, the atmospheric chemistry of esters can be better represented within atmospheric chemical models. However, this work also highlights issues with the current SAR approach, namely the inability to predict hydrogen-bonding interactions, which influence reactivity in the esters and other oxygenated molecules. Alternative SAR approaches and suggestions for future work are proposed
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