21684 research outputs found
Sort by
5th generation district heating and cooling for holistic energy system decarbonisation: Novel system designs and detailed techno-economic assessment
Get PDFTo limit climate breakdown, decarbonising the heating and cooling sector in a cost effective manner represents a crucial challenge. Holistic energy system decarbonisation is recognised as a key solution, relying on sector coupling, energy reuse and energy storage. 5th Generation District Heating and Cooling (5GDHC) presents a promising pathway for holistic decarbonisation. It utilises an ambient temperature water network with decentralised heat pumps to exploit synergies between heating and cooling, to harness low temperature waste heat and allow sector coupling with the electricity grid. However, questions remain on 5GDHC’s hydraulic design, operational stability, economic viability, and overall performance against alternative supply options.
This PhD thesis addresses these gaps by developing and experimentally validating a novel hydraulic design and operational methodology for 5GDHC systems. This design focuses on decentralised variable speed pumping and a centralised passive balancing unit to ensure system stability. Detailed simulation models for the proposed design are also developed and experimentally validated, which are made open access. Additionally, a technoeconomic assessment tool, the Centralisation Analysis Tool for Heat Pump Systems (CATHeaPS), is created to evaluate the economic viability of 5GDHC against other thermal supply options. CATHeaPS is also made open access.
To complete these tasks,
1. A systematic literature review is conducted and integrated with views from leading industry and academic professionals in the field, collected during bespoke interviews on the opportunities and challenges of 5GDHC for holistic decarbonisation. It is found that further research is required on quantifying the range of operational boundaries that make 5GDHC more techno-economically viable, hydraulic design and operation standardisation as well as a business structure redefinition.
2. A novel hydraulic design and suitable control philosophies are developed and experimentally validated. The experiments showed stable operation over a period of 20 hours for all demand regimes without control instabilities. A discussion is conducted on generalisability of findings and full-scale implementations.
3. Bespoke Modelica models are created and validated by building a digital twin of the experiment. A stepwise validation of the assembled digital twin demonstrates that the developed Modelica components effectively capture the behaviour of 5GDHC, with a Coefficient of Determination (R²) for the primary pump flowrates exceeding 0.88 in all cases. The similarity of the results is also seen through an analysis of the overall system behaviour.
4. For the techno-economic comparison of 5GDHC against alternative energy supply strategies for decarbonising heating and cooling, CATHeaPS is employed. CATHeaPS is verified using a direct comparison of outputs and the theoretical results/analysis verification approaches. Economic and environmental analyses are conducted highlighting the impact of cooling and access to waste heat sources. When there is no cooling, 5GDHC performs worse than 4th Generation District Heating (4GDH) for any network topology and consumer class configuration. An annual cooling to heating demand share of 30% (with a demand overlap coefficient of 16%) is required for 5GDHC to start performing better for a higher number of connections per property.
5. A real-world case study with heating and cooling loads and a waste heat source/sink during the winter/summer is used to demonstrate the application of the developed models and methodologies. It quantifies the techno-economic performance of 5GDHC against alternative supply options for the project area. 5GDHC shows a better economic performance than 4GDH with individual Air Condition units for cooling (4GDH&AC) with 227£/MWh compared to 257£/MWh. It is less energy efficient than 4GDH&AC, having an additional 81 tonnes of CO2 over a 40-year period. However, having reversible BHP units at each prosumer allows for a smaller electric capacity requirement, reducing the impact on the electricity grid. A discussion is also present on space constraints, operational complexity, and expansion flexibility.
Altogether, this research delivers a comprehensive framework for designing, simulating, and assessing 5GDHC systems. It facilitates their understanding and ultimately assists the efforts for a holistic energy system decarbonisation
He Who Pays the Piper Calls the Tune: Exploring asymmetry and imbalance in Scottish Local Government finance since 1974
No full textAbstract not currently available
Mitochondrial targeting for inhibition of fumarate hydratase
No full textAbstract not currently available
Calcium-aluminium-rich inclusion populations and abundances within CM chondritic lithologies
No full textC-type asteroids are considered prime candidates for the delivery of water to Earth in the early stages of the Solar System, due to their high-water and volatile content. Carbonaceous Mighei-like (CM) chondrites are water-rich polymict breccias that are thought to originate from these planetesimals. These carbonaceous meteorites have experienced extensive parent body alteration processes and display a diverse range of degrees of aqueous alteration. Among their components, Calcium-Aluminium-rich Inclusions (CAIs) are the first solids to have formed within the Solar System and accreted early onto these asteroidal parent bodies after migrating from their near-solar forming region. Therefore, these inclusions constitute ideal candidates for recording the aqueous alteration events that affected the CM parent body(-ies).
To this end, CAIs from 21 samples from six CM chondrites spanning a wide range of degrees of aqueous alteration (CM2.0-2.9) were selected for investigation. Using a combination of backscatter electron images and energy dispersive X-ray spectroscopy, CAIs were identified, selected, and measured within Asuka 12236, DNG 06004, Paris, and Winchcombe, and CAIs from DNG 06004, LAP 02239, and Winchcombe were classified according to their mineralogical and morphological features. A singular large altered complex aggregate (CAI) from Winchcombe was further studied using electron probe micro-analysis, transmission electron microscopy, and transmission Kikuchi diffraction to determine the potential role of its unusual pre-accretionary mineralogy on secondary mineralisation processes.
Measurements of CAI modal abundances, combined with data from the literature, reveal a clear correlation: CM CAI modal abundance decreases relative to the increasing aqueous alteration of their host lithology. This is due to the progressive alteration and destruction of CAIs through fluid-mediated replacement reactions. Further petrological and geochemical investigations of the CAI populations within Winchcombe reveal that CAIs have been affected differentially by fluid-mediated replacement reactions. Further evidencing that the CM parent body(-ies) likely underwent heterogeneous aqueous alteration processes. This suggests that the initial distribution of CAIs within the CM parent body(-ies) was likely homogeneous, and heterogeneity in the CM CAI record was caused by subsequent fluid-driven alteration events.
During the large-scale investigation of CM CAIs, three rare CompoundChondrule-CAIs (CCCAIs) were identified within Aguas Zarcas and LAP 02239. These objects are described as CAIs enclosed within chondrules and have been previously reported in other major carbonaceous groups (CO, CV, and CH). One CCCAI was subjected to electron backscatter diffraction to test the potential for CAIs to act as nucleation sites for chondrule formation. Additionally, in order to trace the origin of the CCCAI components, oxygen isotopes were measured using secondary ion mass spectrometry. The targets included the CAI and chondrule components of CCCAIs, as well as other CAIs and chondrules from Aguas Zarcas, DNG 06004, LAP 02239, Paris, and Winchcombe for comparison.
Based on the oxygen isotope analysis, the components of the CCCAIs belong to the same CAI and chondrule populations found within the CM lithologies. This led to the proposition of a model for the formation of CCCAIs by the incorporation of CAIs within a precursor ferromagnesian melt during transient heating events in the chondrule forming region. This suggests an early outward migration of near-solar refractory material within 1 Ma after CAI formation (before the formation of a physical barrier, e.g. proto-Jupiter).
The CM CAI populations are diverse in their pre- and post-accretionary histories and can provide invaluable information by constraining the initial and early compositions of the CM parent body(-ies). The methods developed during this thesis could be applied to other carbonaceous groups in order to improve our understanding of early accretion and alteration of asteroidal parent bodies
May Drummond (1696-1777): An unruly Quaker
Get PDFTwo aspects of the history of the Religious Society of Friends (the Quakers) have in the last few decades begun to attract attention namely the state of the Society in the 18thcentury, and the role of women. These are examined in the current work, using the biography of one unusual woman.
In the 18th century Quakers entered what later became known as the Quietist period. They tried to withdraw from the world, placing barriers such as particular dress codes, ways of speaking, non-participation in any cultural activities, and endogamy. Membership was falling. Ministry became dry and uninspiring and meetings became silent. Despite this, evangelically minded Quakers, many of them women, continued to travel preaching at public meetings. These ‘Public Friends’ included May Drummond, the subject of this work. She was born into an elite Edinburgh family on the eve of the Enlightenment and in middle-age joined the Quaker movement. She travelled, preaching, for the rest of her life. She attracted a great deal of publicity, and was the focus of admiration and opprobrium. In many ways she refused to conform to the strictures laid down by the elders. As a result she was disowned, forbidden to preach, and attempts were made to blacken her name.
The present research examines her life in detail, against the background of the Enlightenment and the Quaker Quietist period. The public records reveal her true date of birth. She was not, as had been thought, a girl of twenty-one, but a mature single woman who deliberately turned her back on the life society had mapped out for her. Her life can be traced through contemporary newspapers, her letters, and the diaries and other records left by fellow Quakers.
Because the records of her disownment by the Quakers were kept in detail, this event has formed the main narrative of her life, which has seemed to be one of failure. On the contrary, as this work shows, she was a successful independent woman who defied the norms of both the society she was born into, and the movement she joined. She has been written out of the history of both Scotland in the Enlightenment and the Quaker movement and deserves to take her place in both
Studies into uropathogenic Escherichia coli gene expression in a mouse model of urinary tract infection
No full textAbstract not currently available
Analysis of sustainable socio-technical transition - unpacking the development of the NEV sector from the early 2000s through an innovative conceptual framework
Get PDFThis research investigates the significant growth of China’s New Energy Vehicle (NEV) sector from the early 2000s to the 2020s, evolving from a niche market to a central player in the automotive industry. While previous studies have focused mainly on singular factors, such as policy impacts, this study introduces the Global, Internal, and External Sociotechnical System (GIESTS) Framework, an advanced adaptation of the Multi-Level Perspective (MLP), to analyse China’s NEV transition comprehensively through providing a multidimensional view of China’s electrification journey.
Additionally, the study introduces the Resources-Capabilities Analytics (RCA) Framework to examine firm-level transitions, drawing on the resource-based view and dynamic capability theory. This framework allows for comparisons between different types of automakers, offering more profound insights into how firms navigate the NEV sector’s challenges and opportunities.
Using a mixed-methods approach, combining secondary data analysis, participatory observation, and expert interviews, the research explores the roles of key stakeholders, transition pathways, and how China’s government’s role compares to that of developed countries. It also examines interactions between various transition layers using the GIESTS Framework, revealing how the various factors have influenced the sector’s growth.
The findings provide strategic insights for policymakers and industry leaders, proposing a systematic methodology for understanding complex transitions in socio-technical systems. This thesis significantly contributes to scholarly discussions on socio-technical transitions and offers a valuable guide for stakeholders involved in the ongoing transformation of the NEV industry
Online therapy across the lifespan: an exploration into the perspectives of clients and clinicians
Get PDFAbstract available at each chapter
“Sometimes it protects you, sometimes it hurts you”: An exploration of dissociation, psychosis and trauma
Get PDFAbstract available at each chapter
Frailty assessment in vascular surgery
Get PDFBackground: Frailty describes a syndrome characterised by reduced physiological reserve and increased vulnerability to even minor stressors due to age-associated changes in physiological substrate. Frailty is common in vascular surgery populations and has demonstrated associations with adverse health outcomes and increased risk of mortality. However, in the absence of clear guidelines there is uncertainty over the approach to frailty identification and its management. Frailty identification can be considered the critical first step to improving health outcomes for this vulnerable population. A role is identified for exploring approaches to frailty assessment and the implications this might bring to vascular surgery services.
Aims: This thesis addresses the following aims:
1. To explore the methodological approaches to frailty assessment described
in vascular surgery research and clinical practice.
2. To explore the practical utility of frailty in vascular surgery clinical
practice.
3. To explore stakeholders perceptions of frailty assessment in clinical
practice.
Methods: Three approaches were adopted to target research questions. First a two-part systematic review was performed. The first part included any study describing any form of frailty assessment in vascular surgery populations for any reason. Data collection included which frailty assessment tools were used, the methodological application of each tool and how data was analysed. The second review set out to explore how the clinimetric properties have been assessed for the ten most commonly used frailty assessment tools identified in the aforementioned review. Any study with the aim of exploring any clinimetric property was included. The search criteria was expanded to include studies of any surgical population as initial search strategy found restricting to vascular surgery populations only yielded a low number of eligible studies.
Secondly, a prospective observational study was conducted to explore the practical utility of frailty assessments in clinical practice. Patients were recruited from a vascular rapid-access clinic, baseline data were collected and five different frailty assessments were performed (Clinical Frailty Scale, Healthcare Improvement Scotland FRAIL, Frail NonDisabled questionnaire, subjective clinical assessment and 11-item modified frailty index). Outcome measures include feasibility parameters, comparisons of the demographic differences between
robust and frail patients and clinimetric property assessment (interrater reliability and convergent validity), using clinician-assessed CFS as reference standard. A short-term (30-day) follow-up explores prognostic properties of frailty assessment tools.
Finally, a national mixed methods study recruited vascular surgeons and allied healthcare professionals and explored their perceptions and utilisation of frailty assessment in clinical practice. An 18-item questionnaire was distributed purposively by email with respondents given the option to volunteer for follow-up interview/focus groups through the questionnaire.
Results:
Research aim 1: Screening 5358 records identified 111 eligible studies. Forty-three differing frailty assessment tools were identified. One-third of these failed to assess frailty as a multidomain deficit and there was a reliance on assessing function and presence of comorbidity. Substantial methodological variability in data analysis and lack of methodological description was also identified. Published psychometric and/or clinimetric assessment was available for only 4 of the 10 most commonly used frailty tools. The Clinical Frailty Scale (CFS) was most studied and demonstrated good clinimetric properties within a surgical population.
Research aim 2: A total of 150 patients were recruited. Most were young, male and from areas of greatest social deprivation. Seventy-six (51%) were frail (CFS 5+). Frailty was significantly associated with age, polypharmacy and comorbidity. Clinicians were more likely to consider women frail on end-of bed, this was not replicated in remaining instruments. Compared to CFS, there was excellent agreement with end-of-bed assessment and moderate agreement with HIS FRAIL. The mFI-11 and FiND demonstrated poor agreement and correlation with the remaining frailty assessment instruments which suggests these tools measure different constructs. Due to small numbers, no significant differences were observed on 30-day follow-up, including: mortality, morbidity, length of stay, readmission rate, or nonhome discharge.
Research aim 3: A total of 160 questionnaires were distributed with 60 (37.5%) responses. Respondents were primarily consultant or trainee vascular surgeons but contributions were comprehensive and involved most members of vascular surgery multidisciplinary team members. Responses were received from ten of fourteen Scottish regional health boards. A total of 20 respondents volunteered for follow-up interviews/focus groups across four regional health boards and totalling over 8 hours of recorded interview time. Healthcare workers recognise the importance of identifying and treating frailty. However, assessment lacks a unified approach with clinicians primarily performing subjective assessments. A call for standardising the approach to frailty assessment was made primarily due to a feeling that this would assist in unifying the necessary, and currently, disjointed services into a collaborative multidisciplinary approach to improving health outcomes for patients living with frailty.
Conclusion: Despite frailty being recognised by vascular healthcare professionals as a relevant construct with important clinical considerations, there is substantial heterogeneity in approaches to frailty assessment within vascular surgery research and clinical practice. This might be associated with variability in diagnostic and prognostic accuracy and has generated uncertainty around tool selection. For this reason, a call has been made for adopting a standardised approach to frailty assessment. To support such a movement, the work in this thesis presents data supporting the feasibility of routine frailty screening using standardised tools in an outpatient setting. Surgeons prioritise a prognostic role for such tools while allied healthcare professionals consider frailty in a broader sense, recognising the need for collaborative multidisciplinary approaches to its management as part of improving health care outcomes. Introducing a standardised approach to frailty identification is felt supportive in this movement primarily through guiding unification of language, awareness of a growing problem and to redirect the attention and priorities of multidisciplinary services. As part of achieving shared care goals, a deepened understanding of early-onset frailty and the interplay with mobility-limiting pathology, particularly in considering frailty phenotypically, is recommended
Data sources:
Access Repository Dashboard
Do you manage Open Research Online? Become a CORE Member to access insider analytics, issue reports and manage access to outputs from your repository in the CORE Repository Dashboard! 👇