Now showing items 1-20 of 9606

    • Optimal Energy Resource Allocation in Isolated Micro Grid with Limited Supply Capacity

      Anuebunwa, Ugonna; Mokryani, Geev (IEEE, 2021-09)
      An isolated micro-grid network with limited generating capacity would most likely, end up having operational challenge either due to increasing number of customers, or introduction of new loads onto the network. This is in view of an observed scenario especially in developing countries whereby as load demand increases, installed PV capacity often do not receive commensurate expansion. So, in order to prevent network failure, each user can be allocated certain amount of limited power supply which should not be exceeded. These allotments are dynamic, and they vary at regular time intervals every day depending on their historic load profile data. This work is therefore based on managing power supply from a PV-source operating as an isolated micro-grid with storage capabilities. A power supply scheduling mechanism is introduced which allocates maximum power capacity for every user. Hence communities detached from the grid can enjoy electricity despite shortfalls in power supply capacity. The obtained results evaluated under three scenarios show that allocating energy limits to each user depends on the current capacity of the battery as well as the forecast load demand. This allotment is enforced using variable circuit breakers whose cut-off point is varied based on the prevailing energy demand and supply requirements.
    • Active Distribution Networks Planning Considering Multi-DG Configurations and Contingency Analysis

      Amjad, Bilal; Al-Ja'afreh, Mohammad A.A.; Mokryani, Geev (2021-07-19)
      This paper proposes a novel method for planning active distribution networks (ADNs) with the integration of an active network management (ANM) scheme using coordinated voltage control (CVC) through on-load tap changer (OLTC) transformers. The method was formulated as a security-constrained optimal power flow (SCOPF) problem to minimize total operational costs, which maximizes the utilization of renewable distributed generators (DGs) over a planning horizon. The ANM scheme was applied using OLTC to ensure safe operation and reduce voltage violations in the network. To analyse the impact of ANM, the planning problem was examined both with and without the ANM scheme. Moreover, SCOPF, considering the N-1 line contingency analysis and multi-DG configuration, was implemented to analyse the feasibility of the proposed method and the advantages of ANM under contingency situations. The method was validated on a weakly-meshed 16-bus UK generic distribution system (UKGDS). The results showed that ANM can lower operational costs and maintain network voltage for operation in feasible conditions even in the case of a contingency. Moreover, the ANM scheme mitigated the voltage rise effect caused by DGs and maximized their utilization.
    • Voltage Unbalance Mitigation in Low Voltage Distribution Networks using Time Series Three-Phase Optimal Power Flow

      Al-Ja'afreh, M.A.A.; Mokryani, Geev (IEEE, 2021)
      Due to high penetration of single-phase Photovoltaic (PV) cells into low voltage (LV) distribution networks, several impacts such as voltage unbalance, voltage rise, power losses, reverse power flow arise which leads to operational constraints violation in the network. In this paper, a time series Three Phase Optimal Power Flow (TPOPF) method is proposed to minimize the voltage unbalance in LV distribution networks with high penetration of residential PVs. TPOPF problem is formulated using the current injection method in which the PVs are modelled via a time-varying PV power profile with active and reactive power control. The proposed method is validated on a real LV distribution feeder. The results show that the reactive power management of the PVs helps mitigate the voltage unbalance significantly. Moreover, the voltage unbalance index reduced significantly compared to the case without voltage unbalance minimisation.
    • Enhanced Objective Detection of Retinal Nerve Fiber Bundle Defects in Glaucoma With a Novel Method for En Face OCT Slab Image Construction and Analysis

      Cheloni, R.; Dewsbery, S.D.; Denniss, Jonathan (2021-10-04)
      To introduce and evaluate the performance in detecting glaucomatous abnormalities of a novel method for extracting en face slab images (SMAS), which considers varying individual anatomy and configuration of retinal nerve fiber bundles. Dense central retinal spectral domain optical coherence tomography scans were acquired in 16 participants with glaucoma and 19 age-similar controls. Slab images were generated by averaging reflectivity over different depths below the inner limiting membrane according to several methods. SMAS considered multiple 16 µm thick slabs from 8 to 116 µm below the inner limiting membrane, whereas 5 alternative methods considered single summary slabs of various thicknesses and depths. Superpixels in eyes with glaucoma were considered abnormal if below the first percentile of distributions fitted to control data for each method. The ability to detect glaucoma defects was measured by the proportion of abnormal superpixels. Proportion of superpixels below the fitted first percentile in controls was used as a surrogate false-positive rate. The effects of slab methods on performance measures were evaluated with linear mixed models. The ability to detect glaucoma defects varied between slab methods, χ2(5) = 120.9, P
    • Fundus-controlled perimetry (microperimetry): Application as outcome measure in clinical trials

      Pfau, M.; Jolly, J.K.; Wu, Z.; Denniss, Jonathan; Lad, E.M.; Guymer, R.H.; Fleckenstein, M.; Holz, F.G.; Schmitz-Valckenberg, S. (2021-05)
      Fundus-controlled perimetry (FCP, also called 'microperimetry') allows for spatially-resolved mapping of visual sensitivity and measurement of fixation stability, both in clinical practice as well as research. The accurate spatial characterization of visual function enabled by FCP can provide insightful information about disease severity and progression not reflected by best-corrected visual acuity in a large range of disorders. This is especially important for monitoring of retinal diseases that initially spare the central retina in earlier disease stages. Improved intra- and inter-session retest-variability through fundus-tracking and precise point-wise follow-up examinations even in patients with unstable fixation represent key advantages of these technique. The design of disease-specific test patterns and protocols reduces the burden of extensive and time-consuming FCP testing, permitting a more meaningful and focused application. Recent developments also allow for photoreceptor-specific testing through implementation of dark-adapted chromatic and photopic testing. A detailed understanding of the variety of available devices and test settings is a key prerequisite for the design and optimization of FCP protocols in future natural history studies and clinical trials. Accordingly, this review describes the theoretical and technical background of FCP, its prior application in clinical and research settings, data that qualify the application of FCP as an outcome measure in clinical trials as well as ongoing and future developments.
    • Demountable connections of reinforced concrete structures: Review and future developments

      Figueira, Diogo; Ashour, Ashraf F.; Yildirim, G.; Aldemir, A.; Sahmaran, M. (Elsevier, 2021-12)
      In the current practice, at the end of life of a reinforced concrete structure, it is destructively demolished and the demolition waste is landfilled or recycled. This approach is clearly wasteful of energy, creating serious environmental pollution and at high cost. However, design for demountability/deconstruction (DfD) of reinforced concrete structures would facilitate the future reuse of structural elements at the end of their life, potentially achieving a significant reduction in embodied energy of structures as well as giving the clients the benefit of retaining the value of their assets. In this paper, recent research developments and practical applications of DfD of reinforced concrete structures are reviewed and key technical issues are discussed. The main focus was on connections that should be designed in such a way to allow demounting. The main achievements are outlined, for each type of dry and semi dry connections, along with the aspects that still need to be developed. It is concluded that only semi-dry connections are currently implemented but information available in the literature on dry connections between structural elements is still very scarce. The paper concludes with an outline of some future opportunities and challenges in the application of DfD in concrete construction.
    • The effect of export market-oriented culture on export performance: Evidence from a Sub-Saharan African economy

      Olabode, Oluwaseun E.; Adeola, O.; Assadinia, S. (2018-07)
      Purpose: The purpose of this paper is to examine how export learning capability and export environmental turbulence serve as mechanisms and boundary conditions to link export market-oriented culture to export performance. Design/methodology/approach: A quantitative approach was undertaken to analyse longitudinal data of 249 small- and medium-sized exporting firms in Nigeria, a Sub-Saharan African economy. Findings: Four major findings emerged from the study. First, export market-oriented culture positively influences export performance. Second, possessing an export market-oriented culture results in the development of high export learning capabilities. Third, export learning capability mediates the relationship between export market-oriented culture and export performance. Fourth, increases in export environment turbulence weaken the positive effect of export learning capability on export performance. Research limitations/implications: This study does not investigate moderating effects which might affect the relationship between export market-oriented culture and export learning capability as this was beyond the scope of this study. Originality/value: This study looks at developing economy environment as a unique context to examine the direct, mediating, and moderating effects of export market-oriented culture on export performance.
    • Big data analytics capability and market performance: The roles of disruptive business models and competitive intensity

      Olabode, Oluwaseun E.; Boso, N.; Hultman, M.; Leonidou, C.N. (2021)
      Research shows that big data analytics capability (BDAC) is a major determinant of firm performance. However, scant research has theoretically articulated and empirically tested the mechanisms and conditions under which BDAC influences performance. This study advances existing knowledge on the BDAC–performance relationship by drawing on the knowledge-based view and contingency theory to argue that how and when BDAC influences market performance is dependent on the intervening role of disruptive business models and the contingency role of competitive intensity. We empirically test this argument on primary data from 360 firms in the United Kingdom. The results show that disruptive business models partially mediate the positive effect of BDAC on market performance, and this indirect positive effect is strengthened when competitive intensity increases. These findings provide new perspectives on the business model processes and competitive conditions under which firms maximize marketplace value from investments in BDACs.
    • Evaluation of bandwidth management technique using dynamic LSP tunnelling and LDP in MPLS for sustainable mobile wireless networks

      Mustapha, O.Z.; Hu, Yim Fun; Sheriff, Ray E.; Abd-Alhameed, Raed A.; Ali, M. (2020-03)
      Fairness in bandwidth resource allocation is highly significance to the advancement of the future generation mobile and wireless technologies. It is likely that restriction of bandwidth due to the employment of some scheduling scheme would not be an appropriate option for the future development of communication systems. However, there is need to consider an implementation that would lead to good network performance and avoid unguaranteed bandwidth delivery. This paper focusses on evaluating the performance of Bandwidth Allocation using Dynamic Label Switching Paths (LSPs) Tunnelling and Label Distribution Protocol (LDP) signalling in Multi-Protocol Label Switching (MPLS) network. This will make provision for bandwidth allocation and reservation possible. An appropriate bandwidth allocation would have a positive impact on throughput as well as the delay. The results of an IP (Internet Protocol) Network without MPLS enabled is compared with MPLS model network. Furthermore, implementation of dynamic and static LSPs models are presented with about 75% decrease in packet delay variation for dynamic LSP when compared from static LSP. In addition, the models of bandwidth estimation, bandwidth allocation, delay and jitter are provided. Performance metrics used in this respect for multimedia services (Voice and Video conferencing) confirm that the modified models are improved in comparison with the baseline, having highest throughput of about 51% increment, and packet delay variation decreases drastically.
    • The mean–variance relation: A 24-hour story

      Wang, Wenzhao (2021-11)
      This paper investigates the mean-variance relation during different time periods within trading days. We reveal that there is a positive mean-variance relation when the stock market is closed (i.e., overnight), but the positive relation is distorted when the market is open (i.e., intraday). The evidence offers a new explanation for the weak risk-return tradeoff in stock markets.
    • Institutional Investor Sentiment and the Mean-Variance Relationship: Global Evidence

      Wang, Wenzhao; Duxbury, D. (2021-11)
      Although a cornerstone of traditional finance theory, empirical evidence in support of a positive mean-variance relation is far from conclusive, with the behavior of retail investors commonly thought to be one of the root causes of departures from this expected relationship. The behavior of institutional investors, conventionally thought to be sophisticated and rational, has recently come under closer scrutiny, including in relation to investor sentiment. Drawing together these two strands of literature, this paper examines the impact of institutional investor sentiment on the mean-variance relation in six regions, including Asia (excl. Japan), Eastern Europe, Eurozone, Japan, Latin America, and the US, and across thirtyeight markets. Empirical evidence supports the differential impact of institutional investor sentiment on the mean-variance relation (i.e., positive or negative), both across regions and across markets. In particular, for markets with cultural proneness to overreaction and a low level of market integrity institutional investor sentiment tends to distort the risk-return tradeoff.
    • Living well with dementia: what is possible and how to promote it

      Quinn, Catherine; Pickett, James A.; Litherland, R.; Morris, R.G.; Martyr, A.; Clare, L. (2021)
      Key points: The focus on living well with dementia encourages a more positive and empowering approach. The right support can improve the experience of living with dementia. An holistic approach to assessing the needs of people with dementia and identifying the factors that impact on their well-being is essential. Enabling people to live better requires a broad approach that encompasses both health and social systems and the wider community.
    • What Are the Barriers and Enablers to the Implementation of Pharmacogenetic Testing in Mental Health Care Settings?

      Jameson, Adam; Fylan, Beth; Bristow, Greg C.; Sagoo, G.S.; Dalton, C.; Cardno, A.; Sohal, J.; McLean, Samantha L. (2021-09-22)
      In psychiatry, the selection of antipsychotics and antidepressants is generally led by a trial-and-error approach. The prescribing of these medications is complicated by sub-optimal efficacy and high rates of adverse drug reactions (ADRs). These both contribute to poor levels of adherence. Pharmacogenetics (PGx) considers how genetic variation can influence an individual’s response to a drug. Pharmacogenetic testing is a tool that could aid clinicians when selecting psychotropic medications, as part of a more personalized approach to prescribing. This may improve the use of and adherence to these medications. Yet to date, the implementation of PGx in mental health environments in the United Kingdom has been slow. This review aims to identify the current barriers and enablers to the implementation of PGx in psychiatry and determine how this can be applied to the uptake of PGx by NHS mental health providers. A systematic searching strategy was developed, and searches were carried out on the PsychInfo, EmBase, and PubMed databases, yielding 11 appropriate papers. Common barriers to the implementation of PGx included cost, concerns over incorporation into current workflow and a lack of knowledge about PGx; whilst frequent enablers included optimism that PGx could lead to precision medicine, reduce ADRs and become a more routine part of psychiatric clinical care. The uptake of PGx in psychiatric care settings in the NHS should consider and overcome these barriers, while looking to capitalize on the enablers identified in this review.
    • Psychological and social factors associated with coexisting frailty and cognitive impairment: A systematic review

      Ellwood, Alison; Mountain, Gail; Quinn, Catherine (2021)
      Those living with coexistent frailty and cognitive impairment are at risk of poorer health outcomes. Research often focuses on identifying biological factors. This review sought to identify the association psychological and social factors have with coexisting physical and cognitive decline. Six databases were systematically searched in July 2020. Studies included individuals aged 60 years or older identified as being both frail and cognitively impaired. A narrative synthesis examined patterns within the data. Nine studies were included, most employed a cross-sectional design. Depression was investigated by all nine studies, those with coexistent frailty and cognitive impairment had higher levels of depressive symptoms than peers. Findings were mixed on social factors, although broadly indicate lower education, living alone and lower material wealth were more frequent in those living with coexistent decline. Further research is needed to explore potentially modifiable psychological and social factors which could lead to the development of supportive interventions.
    • Impact of dementia care education and training on health and social care staff knowledge, attitudes and confidence: a cross-sectional survey

      Parveen, Sahdia; Smith, S.J.; Sass, C.; Oyebode, Jan R.; Capstick, Andrea; Dennison, Alison; Surr, C.A. (2021-01-19)
      The aim of this study was to establish the impact of dementia education and training on the knowledge, attitudes and confidence of health and social care staff. The study also aimed to identify the most effective features (content and pedagogical) of dementia education and training. Cross-sectional survey study. Data collection occurred in 2017. Health and social care staff in the UK including acute care, mental health community care trusts, primary care and care homes. All health and social care staff who had completed dementia education and training meeting the minimal standards as set by Health Education England, within the past 5 years were invited to participate in an online survey. A total of 668 health and social care staff provided informed consent and completed an online survey, and responses from 553 participants were included in this study. The majority of the respondents were of white British ethnicity (94.4%) and identified as women (88.4%). Knowledge, attitude and confidence of health and social care staff. Hierarchical multiple regression analysis was conducted. Staff characteristics, education and training content variables and pedagogical factors were found to account for 29% of variance in staff confidence (F=4.13, p<0.001), 22% of variance in attitude (knowledge) (F=3.80, p<001), 18% of the variance in staff knowledge (F=2.77, p<0.01) and 14% of variance in staff comfort (attitude) (F=2.11, p<0.01). The results suggest that dementia education and training has limited impact on health and social care staff learning outcomes. While training content variables were important when attempting to improve staff knowledge, more consideration should be given to pedagogical factors when training is aiming to improve staff attitude and confidence.
    • Fidelity and the impact of patient safety huddles on teamwork and safety culture: an evaluation of the Huddle Up for Safer Healthcare (HUSH) project.

      Lamming, Laura; Montague, Jane; Crosswaite, Kate; Faisal, Muhammad; McDonach, E.; Mohammed, A. Mohammed; Cracknell, A.; Lovatt, A.; Slater, B. (2021-10-01)
      The Patient Safety Huddle (PSH) is a brief multidisciplinary daily meeting held to discuss threats to patient safety and actions to mitigate risk. Despite growing interest and application of huddles as a mechanism for improving safety, evidence of their impact remains limited. There is also variation in how huddles are conceived and implemented with insufficient focus on their fidelity (the extent to which delivered as planned) and potential ways in which they might influence outcomes. The Huddle Up for Safer Healthcare (HUSH) project attempted to scale up the implementation of patient safety huddles (PSHs) in five hospitals - 92 wards - across three UK NHS Trusts. This paper aims to assess their fidelity, time to embed, and impact on teamwork and safety culture. A multi-method Developmental Evaluation was conducted. The Stages of Implementation Checklist (SIC) was used to determine time taken to embed PSHs. Observations were used to check embedded status and fidelity of PSH. A Teamwork and Safety Climate survey (TSC) was administered at two time-points: pre- and post-embedding. Changes in TSC scores were calculated for Trusts, job role and clinical speciality. Observations confirmed PSHs were embedded in 64 wards. Mean fidelity score was 4.9/9. PSHs frequently demonstrated a 'fear free' space while Statistical Process Control charts and historical harms were routinely omitted. Analysis showed a positive change for the majority (26/27) of TSC questions and the overall safety grade of the ward. PSHs are feasible and effective for improving teamwork and safety culture, especially for nurses. PSH fidelity criteria may need adjusting to include factors deemed most useful by frontline staff. Future work should examine inter-disciplinary and role-based differences in TSC outcomes.
    • Moving and handling and managing physiological deterioration of deceased children in hospice cool rooms: practice guidelines for care after death

      Tatterton, Michael J.; Honour, A.; Billington, D.; Kirkby, L.; Lyon, J.A.; Lyon, N.; Gaskin, G. (2021)
      Children’s hospices provide a range of services for babies, children and young people who have life-shortening conditions, including care after death in specialist ‘cool bedrooms’. Caring for children after death is a challenging area of hospice care, with variation seen within, and between organisations. The study aims to identify current practices and to produce guidelines that promote safe practice in moving and handling and managing physiological deterioration of children after death. An electronic questionnaire was sent to all 54 British children’s hospices; 33 responded (=62% of hospices). Variation in the way in which children’s hospices delivered care after death was identified, in terms of the length of stay, care provision and equipment used, owing to demands of individual families and the experience and confidence of practitioners. Internal variation in practice can lead to practitioner anxiety, and risk-taking when providing care, particularly in the presence of family members. Practice recommendations have been made that reflect the practical demands of caring for a child’s body after death; these have been split into two parts: moving and handling considerations and managing physiological deterioration. These recommendations should be used to support the development of policy and practice, allowing organisations to standardise staff expectations and to support practitioners when caring for children after death.
    • Moving and handling children after death: an inductive thematic analysis of the factors that influence decision-making by children’s hospice staff

      Tatterton, Michael J.; Honour, A.; Kirby, L.; Billington, D. (Lippincott Wolters Kluwer, 2021)
      Hospices for children and adolescents in the United Kingdom provide care to the bodies of deceased children, in specially-designed chilled bedrooms called ‘cool rooms’. In an effort to develop resources to support hospice practitioners to provide this specialist area of care, the study aimed to identify the factors that influence decision-making when moving and handling children’s bodies after death in a hospice cool bedroom. An internet-based survey was sent to all practitioners employed by one children’s hospice. A total of 94.9% of eligible staff responded (n=56). An inductive approach to thematic analysis was undertaken, using a six-phase methodological framework. Three core themes were identified that inform practitioners’ perception of appropriateness of moving and handling decisions: care of the body, stages of care, and method of handling. The complexity of decision-making and variation in practice was identified. Practitioners relied on both analytical and initiative decision-making, with more experienced practitioners using an intuitive approach. Evidence-based policy and training influence the perception of appropriateness, and the decisions and behaviour of practitioners. The development of a policy and education framework would support practitioners in caring for children’s bodies after death, standardising expectations and measures of competence in relation to moving and handling tasks.
    • Destitution in pregnancy: Forced migrant women’s lived experience

      Ellul, R.; McCarthy, R.; Haith-Cooper, Melanie (2020-11-02)
      Forced migrant women are increasingly becoming destitute whilst pregnant. Destitution may exacerbate their poor underlying physical and mental health. There is little published research that examines this, and studies are needed to ensure midwifery care addresses the specific needs of these women. This study aimed to explore vulnerable migrant women's lived experience of being pregnant and destitute. Six in-depth individual interviews with forced migrant women who had been destitute during their pregnancy were conducted over one year. A lack of food and being homeless impacted on women's physical and mental health. Women relied on support from the voluntary sector to fill the gaps in services not provided by their local authorities. Although midwives were generally kind and helpful, there was a limit to how they could support the women. There is a gap in support provided by local authorities working to government policies and destitute migrant pregnant women should not have to wait until 34 weeks gestation before they can apply for support. Home office policy needs to change to ensure pregnant migrant women receive support throughout their pregnancy.
    • A systematic review of perinatal social support interventions for asylum-seeking and refugee women residing in Europe

      Balaam, M.C.; Kingdon, C.; Haith-Cooper, Melanie (2021)
      Asylum-seeking and refugee women currently residing in Europe face unique challenges in the perinatal period. A range of social support interventions have been developed to address these challenges. However, little is known about which women value and why. A critical interpretive synthesis was undertaken using peer reviewed and grey literature to explore the nature, context and impact of these perinatal social support interventions on the wellbeing of asylum-seeking and refugee women. Four types of interventions were identified which had varying impacts on women’s experiences. The impacts of the interventions were synthesised into five themes: Alleviation of being alone, Safety and trust, Practical knowledge and learning, being cared for and emotional support, and increased confidence in and beyond the intervention. The interventions which were most valued by women were those using a community-based befriending/peer support approach as these provided the most holistic approach to addressing women’s needs.