Analysis of Low Pressure Steam Turbine Diffuser and Exhaust Hood Systems

This thesis concerns the computational modelling of low pressure (LP) steam turbine exhaust hood flows. A test case for LP last stage blades (LSBs) with a full aerodynamic definition and an accompanying exhaust hood was developed which is representative of current industrial practice. The test case geometry is freely available allowing other researchers to build on this work and is the first of its kind. Studies on this Durham Stage and Exhaust Hood Test Case showed the geometry produces a representative flow pattern and performance metrics comparable to other published research. Using the test case, the effect of condenser cooling water pressure gradient on the hood flow was computed for the first time. A generic boundary condition was developed to represent the transverse condenser cooling water flow and, when applied to the test case, was shown to have a larger influence on the flow asymmetry within the hood than the tip leakage jet. This thesis describes the first application of the non-linear harmonic (NLH) method to couple the LSBs to the exhaust hood. This method enabled the circumferential non-uniformity which develops in the exhaust hood to be transferred across the interface to the stage, in half the computational demand of the full annulus frozen rotor approach. The first review of the influence of inlet circumferential asymmetry on the hood flow field highlighted that modelling its effect is not as crucial as indicated in the literature, unless the diffuser axial length is very compact or if off-design flows are to be studied. A series of recommendations and guidelines for the CFD modelling of steam turbine exhaust hood flows based on this work are supplied. Experimental validation of the Durham Stage and Exhaust Hood Test Case and a comparison of full unsteady studies with the NLH method should be the next steps in this research

The influence of condenser pressure variation and tip leakage on low pressure steam turbine exhaust hood flows

This paper aims to highlight the importance of the accurate computational modelling of both the inlet and outlet exhaust hood boundary conditions. The computations presented are calculated using the public domain low pressure exhaust diffuser test case proposed by Burton in 2012. The original test case did not include the effect of tip leakage on diffuser flows, but this paper describes the inclusion of tip leakage and the results are shown to be in line with the outputs produced by other authors. The key advance in this paper is that calculations were conducted with a representative condenser pressure gradient caused by the temperature variation inside the condenser tube nest. It is shown that accurately modelling the exit boundary calculation has a large influence on the flow structure and a smaller influence on the pressure recovery inside the exhaust diffuser. This influence is smaller than that seen by other authors when including unsteady effects or accounting for the circumferential non-uniformity of the turbine exit flow but will need to be included in design calculations as diffuser design advances

Safe, Ethical and Sustainable : Framing the Argument

The authors have previously articulated the need to think beyond safety to encom-pass ethical and environmental (sustainability) concerns, and to address these concerns through the medium of argumentation. However, the scope of concerns is very large and there are other challenges such as the need to make trade-offs between incommensurable concerns. The paper outlines an approach to these challenges through suitably framing the argument and illustrates the approach by considering alternative concept designs for an autonomous mobility service

Refining fine sediment source identification through integration of spatial modelling, concentration monitoring and source tracing: A case study in the Great Barrier Reef catchments

Excess fine sediment delivery is a major contributor to the declining health of the Great Barrier Reef and identifying the dominant source areas of fine sediment has been critical to prioritising erosion remediation programs. The Bowen River catchment within the Burdekin Basin has been recognised as a major contributor and hence received considerable research investment over the last two decades. This study adopts a novel approach to integrate three independently derived sediment budgets produced from a catchment scale sediment budget model (Dynamic SedNet), targeted tributary water quality monitoring and geochemical sediment source tracing to refine and map the sediment source zones within the Bowen catchment. A four year study of water quality monitoring combined with modelled discharge estimates and geochemical source tracing both identified that the Little Bowen River and Rosella Creek were the largest sources of sediment in the Bowen River catchment. Both data sets contradicted initial synoptic sediment budget model predictions due to inadequate representation of hillslope and gully erosion. Recent improvements in model inputs have resulted in predictions that are consistent with the field data and are of finer resolution within the identified source areas. Priorities for further investigation of erosion processes are also revealed. Examining the benefits and limitations of each method indicates that these are complimentary methods which can effectively be used as multiple lines of evidence. An integrated dataset such as this provides a higher level of certainty in the prediction of fine sediment sources than a single line of evidence dataset or model. The use of high quality, integrated datasets to inform catchment management prioritisation will provide greater confidence for decision makers when investing in catchment management

2017 Scientific Consensus Statement: land use impacts on the Great Barrier Reef water quality and ecosystem condition, Chapter 2: sources of sediment, nutrients, pesticides and other pollutants to the Great Barrier Reef

This chapter provides an up-to-date review of the state of knowledge relating to the source of sediment and nutrients as well as pesticides and other pollutants delivered to the Great Barrier Reef from adjacent catchments. The strengths and limitations of the various datasets are also discussed. Collectively, sediment, nutrients, pesticides and other pollutants (e.g. petroleum hydrocarbons, pharmaceuticals) are described as ‘pollutants’. This chapter is focused on defining the major source areas of these pollutants across the Great Barrier Reef, how these sources have varied in space and time, the major processes (e.g. hillslope, gully and streambank erosion) delivering these pollutants, their relative loads to the Great Barrier Reef and a summary of the main drivers in terms of land use, land condition and agricultural practices. Plot- and paddock-scale studies, including the effectiveness of remediation approaches, are summarised in Chapter 4. Acknowledging that all forms of data used to estimate pollutant loads to the Great Barrier Reef have constraints and limitations, this review uses a ‘multiple lines of evidence’ approach and draws on data from three main sources. These include the Queensland Government load monitoring data, the latest Queensland Government whole of Great Barrier Reef Source Catchments modelling results (which underpin the Report Card 2015) as well as a summary of the numerous individual research projects and synthesis reports published over the last four years. Data and information are included that was published, publicly available and that had undergone a peer review process. In a few cases, grey literature (e.g. consulting reports) and journal publications currently in review are included. A synthesis of the broad findings of this chapter are outlined below and in Table 1. A detailed description of what has changed since the last Scientific Consensus Statement is provided in Table 20

Mind the Gaps: Assuring the Safety of Autonomous Systems from an Engineering, Ethical, and Legal Perspective

This paper brings together a multi-disciplinary perspective from systems engineering, ethics, and law to articulate a common language in which to reason about the multi-faceted problem of assuring the safety of autonomous systems. The paper's focus is on the “gaps” that arise across the development process: the semantic gap, where normal conditions for a complete specification of intended functionality are not present; the responsibility gap, where normal conditions for holding human actors morally responsible for harm are not present; and the liability gap, where normal conditions for securing compensation to victims of harm are not present. By categorising these “gaps” we can expose with greater precision key sources of uncertainty and risk with autonomous systems. This can inform the development of more detailed models of safety assurance and contribute to more effective risk control

Getting back to life after stroke: co-designing a peer-led coaching intervention to enable stroke survivors to rebuild a meaningful life after stroke

Purpose: Rebuilding one’s life after stroke is a key priority persistently identified by patients yet professionally led interventions have little impact. This co-design study constructs and tests a novel peer-led coaching intervention to improve post-stroke leisure and general social participation. Methods: This study followed the principles of co-design by actively engaging and harnessing the knowledge of stroke survivors in order to develop and test a peer-lead coaching intervention. Phase 1 assessed function, mood, and involvement in leisure and social activities 6 months following stroke (n = 79). Phase 2 involved semi-structured, in-depth interviews with 18 stroke survivors, and 10 family carers to explore experiences related to social and leisure participation. Phase 3 tested the co-designed peer-led coaching intervention. Data collected also included co-design feedback sessions and a training workshop with selected peer coaches and in addition, interviews with stroke survivors and their peer coaches at two time-points: following the training program (n = 5) and delivery of the intervention (n = 2). Results: A peer-coaching intervention was successfully co-designed and tested combining the use of lay knowledge sociocognitive and self-regulatory theories with principles of transformational leadership theory. Both peers and stroke survivors reported having benefited at a personal level. Conclusions: This study reports on an innovative community-based and peer-led intervention and its results have generated new evidence on how stroke survivors engage with and respond to peer coaching support. It further provides a theoretical platform for designing and implementing peer interventions. Hence, these results have the potential to inform the development of future peer coaching intervention not only for stroke rehabilitation but also for a wide range of chronic conditions. - Implications for rehabilitation - The results of this co-design study, if replicated and extended, provide a theoretical framework to guide rehabilitation professionals about the optimal timing of peer-coaching interventions and contextual factors that need to be taken into account. - Applying transformational leadership theory principles to the training of peers may prove useful at the time of the implementation of a coaching intervention. - Peer-led coaching interventions, which are community-based and tailored to stroke survivors at the time of discharge, may help support re-engagement in social and leisure activities

Getting back to life after stroke: co-designing a peer-led coaching intervention to enable stroke survivors to rebuild a meaningful life after stroke

PurposeRebuilding one’s life after stroke is a key priority persistently identified by patients yet professionally led interventions have little impact. This co-design study constructs and tests a novel peer-led coaching intervention to improve post-stroke leisure and general social participation. MethodsThis study followed the principles of co-design by actively engaging and harnessing the knowledge of stroke survivors in order to develop and test a peer-lead coaching intervention. Phase 1 assessed function, mood and involvement in leisure and social activities six months following stroke (n=79). Phase 2 involved semi-structured, in-depth interviews with 18 stroke survivors and 10 family carers to explore experiences related to social and leisure participation. Phase 3 tested the co-designed peer-led coaching intervention. Data collected also included co-design feedback sessions and a training workshop with selected peer coaches and in addition, interviews with stroke survivors and their peer coaches at two time-points: following the training programme (n=5) and delivery of the intervention (n=2). Results A peer coaching intervention was successfully co-designed and tested combining the use of lay knowledge sociocognitive and self-regulatory theories with principles of transformational leadership theory. Both peers and stroke survivors reported having benefited at a personal level. ConclusionsThis study reports on an innovative community-based and peer-led intervention and its results have generated new evidence on how stroke survivors engage with and respond to peer coaching support. It further provides a theoretical platform for designing and implementing peer interventions. Hence, these results have the potential to inform the development of future peer coaching intervention not only for stroke rehabilitation but also for a wide range of chronic conditions

Efficiency and safety of varying the frequency of whole blood donation (INTERVAL): a randomised trial of 45 000 donors

Background: Limits on the frequency of whole blood donation exist primarily to safeguard donor health. However, there is substantial variation across blood services in the maximum frequency of donations allowed. We compared standard practice in the UK with shorter inter-donation intervals used in other countries. Methods: In this parallel group, pragmatic, randomised trial, we recruited whole blood donors aged 18 years or older from 25 centres across England, UK. By use of a computer-based algorithm, men were randomly assigned (1:1:1) to 12-week (standard) versus 10-week versus 8-week inter-donation intervals, and women were randomly assigned (1:1:1) to 16-week (standard) versus 14-week versus 12-week intervals. Participants were not masked to their allocated intervention group. The primary outcome was the number of donations over 2 years. Secondary outcomes related to safety were quality of life, symptoms potentially related to donation, physical activity, cognitive function, haemoglobin and ferritin concentrations, and deferrals because of low haemoglobin. This trial is registered with ISRCTN, number ISRCTN24760606, and is ongoing but no longer recruiting participants. Findings: 45 263 whole blood donors (22 466 men, 22 797 women) were recruited between June 11, 2012, and June 15, 2014. Data were analysed for 45 042 (99·5%) participants. Men were randomly assigned to the 12-week (n=7452) versus 10-week (n=7449) versus 8-week (n=7456) groups; and women to the 16-week (n=7550) versus 14-week (n=7567) versus 12-week (n=7568) groups. In men, compared with the 12-week group, the mean amount of blood collected per donor over 2 years increased by 1·69 units (95% CI 1·59–1·80; approximately 795 mL) in the 8-week group and by 0·79 units (0·69–0·88; approximately 370 mL) in the 10-week group (p<0·0001 for both). In women, compared with the 16-week group, it increased by 0·84 units (95% CI 0·76–0·91; approximately 395 mL) in the 12-week group and by 0·46 units (0·39–0·53; approximately 215 mL) in the 14-week group (p<0·0001 for both). No significant differences were observed in quality of life, physical activity, or cognitive function across randomised groups. However, more frequent donation resulted in more donation-related symptoms (eg, tiredness, breathlessness, feeling faint, dizziness, and restless legs, especially among men [for all listed symptoms]), lower mean haemoglobin and ferritin concentrations, and more deferrals for low haemoglobin (p<0·0001 for each) than those observed in the standard frequency groups. Interpretation: Over 2 years, more frequent donation than is standard practice in the UK collected substantially more blood without having a major effect on donors' quality of life, physical activity, or cognitive function, but resulted in more donation-related symptoms, deferrals, and iron deficiency. Funding: NHS Blood and Transplant, National Institute for Health Research, UK Medical Research Council, and British Heart Foundation

Evaluating the effect of a digital health intervention to enhance physical activity in people with chronic kidney disease (Kidney BEAM): a multicentre, randomised controlled trial in the UK

BACKGROUND: Remote digital health interventions to enhance physical activity provide a potential solution to improve the sedentary behaviour, physical inactivity, and poor health-related quality of life that are typical of chronic conditions, particularly for people with chronic kidney disease. However, there is a need for high-quality evidence to support implementation in clinical practice. The Kidney BEAM trial evaluated the clinical effect of a 12-week physical activity digital health intervention on health-related quality of life. METHODS: In a single-blind, randomised controlled trial conducted at 11 centres in the UK, adult participants (aged ≥18 years) with chronic kidney disease were recruited and randomly assigned (1:1) to the Kidney BEAM physical activity digital health intervention or a waiting list control group. Randomisation was performed with a web-based system, in randomly permuted blocks of six. Outcome assessors were masked to treatment allocation. The primary outcome was the difference in the Kidney Disease Quality of Life Short Form version 1.3 Mental Component Summary (KDQoL-SF1.3 MCS) between baseline and 12 weeks. The trial was powered to detect a clinically meaningful difference of 3 arbitrary units (AU) in KDQoL-SF1.3 MCS. Outcomes were analysed by an intention-to-treat approach using an analysis of covariance model, with baseline measures and age as covariates. The trial was registered with ClinicalTrials.gov, NCT04872933. FINDINGS: Between May 6, 2021, and Oct 30, 2022, 1102 individuals were assessed for eligibility, of whom 340 participants were enrolled and randomly assigned to the Kidney BEAM intervention group (n=173) or the waiting list control group (n=167). 268 participants completed the trial (112 in the Kidney BEAM group and 156 in the waiting list control group). All 340 randomly assigned participants were included in the intention-to treat population. At 12 weeks, there was a significant improvement in KDQoL-SF.13 MCS score in the Kidney BEAM group (from mean 44·6 AU [SD 10·8] at baseline to 47·0 AU [10·6] at 12 weeks) compared with the waiting list control group (from 46·1 AU [10·5] to 45·0 AU [10·1]; between-group difference of 3·1 AU [95% CI 1·8-4·4]; p<0·0001). INTERPRETATION: The Kidney BEAM physical activity platform is an efficacious digital health intervention to improve mental health-related quality of life in patients with chronic kidney disease. These findings could facilitate the incorporation of remote digital health interventions into clinical practice and offer a potential intervention worthy of investigation in other chronic conditions. FUNDING: Kidney Research UK