926 research outputs found

    Resilience Assessment of Offshore Wind-to-Hydrogen Systems

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    Low-cost green hydrogen production will be key in reaching net zero carbon emissions by 2050. Green hydrogen can be produced by electrolysis using renewable energy, including wind energy. However, the configuration of offshore wind-to-hydrogen systems is not yet standardised. For example, electrolysis can take place onshore or offshore. This work presents a framework to assess and quantify which configuration is more resilient, so that security of hydrogen supply is incorporated in strategic decisions with the following key findings. First, resilience should be assessed according to hydrogen supply, rather than hydrogen production. This allows the framework to be applicable for all identified system configurations. Second, resilience can be quantified according to the quantity, ratio, and lost revenue of the unsupplied hydrogen

    Primary frequency response from hydrogen-based bidirectional vector coupling storage:modelling and demonstration using power-hardware-in-the-loop simulation

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    To meet reduction targets for carbon emissions and improve the flexibility and security of the energy supply, future energy networks will require enhanced energy vector coupling in addition to the generation of energy from renewable sources. Increased renewable generation penetration significantly affects the electrical grid’s inertia and consequently the severity and regularity of frequency deviations from nominal values. Bidirectional Hydrogen-based Vector Coupling Storage (VCS) has been explored as a means to provide primary frequency response (PFR) services to the electrical network. This paper demonstrates the use of Power Hardware-In-the-Loop (PHIL) simulation and Digital Twin (DT) technique for such an application. This new suggested structure of VCS is composed of grid-scale electrolysers, fuel cells, and hydrogen storage. Existing works focus on unidirectional VCS, and also use simplifications or neglect the impacts of power converters on the performance of the VCS. In addition, these works do not have any control over the hydrogen storage, therefore there is no guarantee that there will be enough energy available in the storage to meet the PFR service responsibilities. This paper presents the dynamic models of electrolysis, fuel cell stacks, and hydrogen storage as a DT. The key parameters affecting the behaviours of these main components are considered. The power converters’ accurate impact on the VCS’s performance is considered through PHIL simulations. The level of stored hydrogen is also considered in the VCS controller. The DT representing the VCS is integrated with the PHIL setup representing the deployment environment. The impact of VCS is then analysed as it propagates to the deployment environment. Results of the considered case studies demonstrate that the size of the VCS plays a significant role in bringing the frequency to the statutory allowed range. In addition, more VCS capacity was installed, the nadir frequency improved. Furthermore, the VCS is fast enough to offer PFR. The response times of the VCS were 2.857 s (during under-frequency periods), corresponding to the operation of the fuel cells, and 2.252 s during over-frequency periods, corresponding to electrolyser operation.</p

    Towards 2050 net zero carbon infrastructure:a critical review of key decarbonization challenges in the domestic heating sector in the UK

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    One of the most challenging sectors to meet “Net Zero emissions” target by 2050 in the UK is the domestic heating sector. This paper provides a comprehensive literature review of the main challenges of heating systems transition to low carbon technologies in which three distinct categories of challenges are discussed. The first challenge is of decarbonizing heat at the supply side, considering specifically the difficulties in integrating hydrogen as a low-carbon heating substitute to the dominant natural gas. The next challenge is of decarbonizing heat at the demand side, and research into the difficulties of retrofitting the existing UK housing stock, of digitalizing heating energy systems, as well as ensuring both retrofits and digitalization do not disproportionately affect vulnerable groups in society. The need for demonstrating innovative solutions to these challenges leads to the final focus, which is the challenge of modeling and demonstrating future energy systems heating scenarios. This work concludes with recommendations for the energy research community and policy makers to tackle urgent challenges facing the decarbonization of the UK heating sector.</p

    MicroGrid Resilience-Oriented Scheduling:A Robust MISOCP Model

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    This article introduces a Robust Mixed-Integer Second Order Cone Programming (R-MISOCP) model for the resilience-oriented optimal scheduling of microgrids (MGs). This is developed for MGs that are islanded due to a scheduled interruption from the main grid, where minimizing both operational costs and load shedding is critical. The model introduced presents two main benefits. Firstly, an accurate second order cone power flow model (SOC-PF) is used, which ensures global optimality. Through a comparison with a piecewise linear power flow model on a modified IEEE 33 bus network, it is demonstrated that failure to accurately model power flow equations, can result in a significant underestimation of the operational cost of almost 12%. Secondly, uncertainty is modelled using a robust approach which allows trade-offs between the uncertainty that a MG operator is willing to tolerate, and performance. In this article, performance criteria considered are operational cost and load shedding. Market price, demand, renewable generation and islanding duration are considered as uncertain variables. Results show that by controlling the budget of uncertainty, the MG operator can achieve an almost 20% reduction in the operating cost, compared to a fully robust schedule, while achieving 0% probability of shedding more demand than expected

    Midwifery students’ views and experiences of birth on mainstream factual television

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    © 2020 Objectives: To investigate midwifery students’ experiences of viewing childbirth on mainstream factual television and to explore implications for student career intentions and potential pedagogical uses of television excerpts in midwifery education. Design: Twenty-two undergraduate midwifery students at one of two universities took place in focus groups between February and June 2019. Ethical approval was obtained at both sites. Thematic analysis was employed to generate key themes from the data. Setting: Two UK universities based in the East Midlands and East Yorkshire regions of England. Participants: Twenty-two midwifery students at any stage of their studies. Findings: Researchers generated four key themes from the data a) Changed Perspectives on Televised Childbirth, b) Representations of Midwives and Social Implications, c) Representation of Childbirth and Social Implications and d) The Role of Televising Childbirth in Midwifery Education. Key conclusions: Midwifery students often experience a change of perspective on birth on television as they acquire new knowledge and skills. They recognise the potential social implications of how childbirth and midwifery are represented on television. Pedagogical use of televised birth has potential benefits but needs further investigation in the context of midwifery education. Implications for practice: Midwifery students are likely to begin their studies with pre-existing views and experiences around how birth is represented on mainstream factual television. They may need support to reflect on these to consider their expectations of the profession, to effectively support childbearing women and to potentially influence future production of media images of childbirth

    Measuring antenatal depressive symptoms across the world:A validation and cross-country invariance analysis of the patient health questionnaire-9 (PHQ-9) in eight diverse low-resource settings

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    Measures that produce valid and reliable antenatal depressive symptom scores in low-resource country contexts are important for efforts to illuminate risk factors, outcomes, and effective interventions in these contexts. Establishing the psychometric comparability of scores across countries also facilitates analyses of similarities and differences across contexts. To date, however, few studies have evaluated the psychometric properties and comparability of the most widely used antenatal depressive symptom measures across diverse cultural, political, and social contexts. To address this gap, we used data from the Evidence for Better Lives Study—Foundational Research (EBLS-FR) project to examine the internal consistency reliability, nomological network validity, and cross-country measurement invariance of the nine-item version of the Patient Health Questionnaire (PHQ-9) in antenatal samples across eight low-resource contexts. We found that the PHQ-9 scores had good internal consistency across all eight countries. Correlations between PHQ-9 scores and constructs conceptually associated with depression were generally consistent, with a few exceptions. In measurement invariance analyses, only partial metric invariance held and only across four of the countries. Our results suggest that the PHQ-9 yields internally consistent scores when administered in culturally diverse antenatal populations; however, the meaning of the scores may vary. Thus, interpretation of PHQ-9 scores should consider local meanings of symptoms of depression to ensure that context-specific conceptualizations and manifestations of antenatal depressive symptoms are adequately reflected.</p

    Measuring Antenatal Depressive Symptoms Across the World: A Validation and Cross-Country Invariance Analysis of the Patient Health Questionnaire-9 (PHQ-9) in Eight Diverse Low-Resource Settings

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    Measures that produce valid and reliable antenatal depressive symptom scores in low-resource country contexts are important for efforts to illuminate risk factors, outcomes, and effective interventions in these contexts. Establishing the psychometric comparability of scores across countries also facilitates analyses of similarities and differences across contexts. To date, however, few studies have evaluated the psychometric properties and comparability of the most widely used antenatal depressive symptom measures across diverse cultural, political, and social contexts. To address this gap, we used data from the Evidence for Better Lives Study—Foundational Research (EBLS-FR) project to examine the internal consistency reliability, nomological network validity, and cross-country measurement invariance of the nine-item version of the Patient Health Questionnaire (PHQ-9) in antenatal samples across eight low-resource contexts. We found that the PHQ-9 scores had good internal consistency across all eight countries. Correlations between PHQ-9 scores and constructs conceptually associated with depression were generally consistent, with a few exceptions. In measurement invariance analyses, only partial metric invariance held and only across four of the countries. Our results suggest that the PHQ-9 yields internally consistent scores when administered in culturally diverse antenatal populations; however, the meaning of the scores may vary. Thus, interpretation of PHQ-9 scores should consider local meanings of symptoms of depression to ensure that context-specific conceptualizations and manifestations of antenatal depressive symptoms are adequately reflecte

    TransfOrming Transnational intErcultural sensitivity for Midwifery students through an inclusive mobility model: A mixed-method evaluation of the TOTEMM project

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    Background: Contemporary midwifery curricula require that student midwives have insight and understanding of global health practice and intercultural sensitivity. The current mobility model excludes large numbers of students from engaging in transnational learning. Objectives: 1) to evaluate midwifery students' experiences of blended mobility; 2) to investigate if the combination of virtual and physical mobility activities supported development of intercultural sensitivity and soft skills. Design: Multi-centre mixed-methods study. Settings: Four European Higher Education Institutions located in England, Italy, Estonia and The Netherlands. Participants: Sixty-four midwifery students studying in one of the four partner institutions selected as study sites and who participated in the TOTEMM blended mobility scheme took part in the evaluation. Methods: Data were collected through two online surveys, face-to-face focus groups and learning analytics. Descriptive summary statistical analysis of survey data was undertaken. Focus group discussions were subjected to thematic analysis. Findings from the quantitative survey and qualitative focus groups were merged using a convergent mixed methods approach. Learning Analytics were interpreted as complementary to the above components, to further triangulate the findings. Results: Both virtual and physical components were evaluated positively by students, with high engagement confirmed by learning analytics. A statistically significant increase in the mean of the Total Intercultural Sensitivity Scale score was seen between the pre- and post-mobility surveys, indicating participation in the TOTEMM mobility model was associated with enhanced intercultural sensitivity. Positive effects on confidence, open-mindedness, empathy, interaction and non-judgment were shared by participants. Conclusions: TOTEMM is an innovative inclusive approach to enable a diverse student group to benefit from transnational learning, including the development of intercultural sensitivity. The TOTEMM blended mobility model has potential for integration into future midwifery curricula and programmes in the four partner settings involved in TOTEMM and utility for the wider European context

    AGILE-ACCORD: A Randomized, Multicentre, Seamless, Adaptive Phase I/II Platform Study to Determine the Optimal Dose, Safety and Efficacy of Multiple Candidate Agents for the Treatment of COVID-19: A structured summary of a study protocol for a randomised platform trial.

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    OBJECTIVES: Phase I - To determine the optimal dose of each candidate (or combination of candidates) entered into the platform. Phase II - To determine the efficacy and safety of each candidate entered into the platform, compared to the current Standard of Care (SoC), and recommend whether it should be evaluated further in a later phase II & III platforms. TRIAL DESIGN: AGILE-ACCORD is a Bayesian multicentre, multi-arm, multi-dose, multi-stage open-label, adaptive, seamless phase I/II randomised platform trial to determine the optimal dose, activity and safety of multiple candidate agents for the treatment of COVID-19. Designed as a master protocol with each candidate being evaluated within its own sub-protocol (Candidate Specific Trial (CST) protocol), randomising between candidate and SoC with 2:1 allocation in favour of the candidate (N.B the first candidate has gone through regulatory approval and is expected to open to recruitment early summer 2020). Each dose will be assessed for safety sequentially in cohorts of 6 patients. Once a phase II dose has been identified we will assess efficacy by seamlessly expanding into a larger cohort. PARTICIPANTS: Patient populations can vary between CSTs, but the main eligibility criteria include adult patients (≄18 years) who have laboratory-confirmed infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). We will include both severe and mild-moderate patients defined as follows: Group A (severe disease) - patients with WHO Working Group on the Clinical Characteristics of COVID-19 infection 9-point ordinal scale of Grades 4 (hospitalised, oxygen by mask or nasal prongs), 5 (hospitalised, non-invasive ventilation or high flow oxygen), 6 (hospitalised, intubation and mechanical ventilation) or 7 (hospitalised, ventilation and additional organ support); Group B (mild-moderate disease) - ambulant or hospitalised patients with peripheral capillary oxygen saturation (SpO2) >94% RA. If any CSTs are included in the community setting, the CST protocol will clarify whether patients with suspected SARS-CoV-2 infection are also eligible. Participants will be recruited from England, North Ireland, Wales and Scotland. INTERVENTION AND COMPARATOR: Comparator is the current standard of care (SoC), in some CSTs plus placebo. Candidates that prevent uncontrolled cytokine release, prevention of viral replication, and other anti-viral treatment strategies are at various stages of development for inclusion into AGILE-ACCORD. Other CSTs will be added over time. There is not a set limit on the number of CSTs we can include within the AGILE-ACCORD Master protocol and we will upload each CST into this publication as each opens to recruitment. MAIN OUTCOMES: Phase I: Dose limiting toxicities using Common Terminology Criteria for Adverse Events v5 Grade ≄3 adverse events. Phase II: Agreed on a CST basis depending on mechanism of action of the candidate and patient population. But may include; time to clinical improvement of at least 2 points on the WHO 9-point category ordinal scale [measured up to 29 days from randomisation], progression of disease (oxygen saturation (SaO2) <92%) or hospitalization or death, or change in time-weighted viral load [measured up to 29 days from randomisation]. RANDOMISATION: Varies with CST, but default is 2:1 allocation in favour of the candidate to maximise early safety data. BLINDING (MASKING): For the safety phase open-label although for some CSTs may include placebo or SoC for the efficacy phase. NUMBERS TO BE RANDOMISED (SAMPLE SIZE): Varies between CSTs. However simulations have shown that around 16 participants are necessary to determine futility or promise of a candidate at a given dose (in efficacy evaluation alone) and between 32 and 40 participants are required across the dose-finding and efficacy evaluation when capping the maximum number of participants contributing to the evaluation of a treatment at 40. TRIAL STATUS: Master protocol version number v5 07 May 2020, trial is in setup with full regulatory approval and utilises several digital technology solutions, including Medidata's Rave EDC [electronic data capture], RTSM for randomisation and patient eConsent on iPads via Rave Patient Cloud. The recruitment dates will vary between CSTs but at the time of writing no CSTs are yet open for recruitment. TRIAL REGISTRATION: EudraCT 2020-001860-27 14th March 2020 FULL PROTOCOL: The full protocol is attached as an additional file, accessible from the Trials website (Additional file 1). In the interest in expediting dissemination of this material, the familiar formatting has been eliminated; this Letter serves as a summary of the key elements of the full protocol
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