Electrical fault management orientated design of future electrical propulsion aircraft

Electrical propulsion aircraft (EPA) have been cited as the future of aviation, enabling greener, quieter, more efficient aircraft. However, due to the stringent requirements surrounding aircraft certification, these novel EPA concepts will need to demonstrate high levels of safety and reliability if electrified flight is ever to become a mainstream mode of passenger transportation. Therefore, robust electrical fault management (FM) is necessary to maintain critical levels of aircraft thrust and to enable high confidence in the reliability and safety of future EPA designs. To date, electrical FM for EPA has been done at a first-pass, minimal level or not at all. For electrical FM to be effective, it must be integrated into the aircraft design from an early stage. This dictates that a novel approach to the design of electrical architectures for EPA is required which addresses the current uncertainty in the availability of suitable FM technologies for future EPA electrical architectures. Therefore, a first-of-kind FM strategy map is presented which identifies projections on the progression of key areas of future EPA-specific FM technology development and acts as a pre-cursor to future FM technology roadmaps. Furthermore, the FM orientated early-stage electrical architecture design methodology presented in this thesis derives feasible, FM-capable electrical architectures for a given EPA concept and captures significant assumptions which impact the down selection process. Since any novel EPA electrical architecture will require some form of testing in hardware, a novel framework for strategic FM demonstrator development is then proposed and the FM test goals for different levels of demonstrator are identified. This strategic development of critical aspects of FM and early integration of FM requires a portfolio of FM demonstrators and test beds for EPA and is crucial if unproven, future EPA electrical architectures are to reach high confidence.Electrical propulsion aircraft (EPA) have been cited as the future of aviation, enabling greener, quieter, more efficient aircraft. However, due to the stringent requirements surrounding aircraft certification, these novel EPA concepts will need to demonstrate high levels of safety and reliability if electrified flight is ever to become a mainstream mode of passenger transportation. Therefore, robust electrical fault management (FM) is necessary to maintain critical levels of aircraft thrust and to enable high confidence in the reliability and safety of future EPA designs. To date, electrical FM for EPA has been done at a first-pass, minimal level or not at all. For electrical FM to be effective, it must be integrated into the aircraft design from an early stage. This dictates that a novel approach to the design of electrical architectures for EPA is required which addresses the current uncertainty in the availability of suitable FM technologies for future EPA electrical architectures. Therefore, a first-of-kind FM strategy map is presented which identifies projections on the progression of key areas of future EPA-specific FM technology development and acts as a pre-cursor to future FM technology roadmaps. Furthermore, the FM orientated early-stage electrical architecture design methodology presented in this thesis derives feasible, FM-capable electrical architectures for a given EPA concept and captures significant assumptions which impact the down selection process. Since any novel EPA electrical architecture will require some form of testing in hardware, a novel framework for strategic FM demonstrator development is then proposed and the FM test goals for different levels of demonstrator are identified. This strategic development of critical aspects of FM and early integration of FM requires a portfolio of FM demonstrators and test beds for EPA and is crucial if unproven, future EPA electrical architectures are to reach high confidence

Hybrid electric aircraft : state of the art and key electrical system challenges

In both Europe and the USA, the aerospace sector is actively pursuing revolutionary design concepts to further improve the environmental impact of air travel. This is partly a result of increasing pressure on the industry from government and other organisations to reduce emissions , despite the continuing increase in air traffic [1] . The aggressive targets set by NASA and the EU [1, 2, 3] (e.g. the Advisory Coun cil for Aviation Research and Innovation in Europe has a target of a 75% reduction in CO2 emissions and a 90% reduction of NOx emissions by 2050) cannot be achieved through marginal improvements in turbine technology or aircraft design. Rather, disruptive technologies and more innovative aircraft must be considered

Establishing viable fault management strategies for distributed electrical propulsion aircraft

Electrical propulsion has the potential to increase aircraft performance. However, this will require the design and development of an appropriate aircraft electrical system to power the propulsor motors. In order to protect this system against electrical faults, which have the potential to threaten the safety of the aircraft, a robust fault management strategy (FMS) is required. The FMS will comprise aspects of system design such as redundancy, reliability and reconfiguration and will rely on a range of protection devices deployed on the electrical system to intercept and manage faults. The electrical architecture will be shaped by the FMS as this will determine the optimal configuration to enable security of supply. The protection system is integral to the system design. Hence it must to be considered from the outset, as part of the wider aircraft concept development. This paper presents a robust framework to develop the optimal FMS for an electrical propulsion aircraft, which is subject to all the relevant aircraft constraints and incorporates the available protection devices for a chosen aircraft for a given developmental timeframe. A case study is then presented in which this protection design methodology is applied to the NASA STARC-ABL aircraft concept in order to demonstrate that the available protection for an electrical propulsion aircraft defines the possible electrical architectures

Impact of key design constraints on fault management strategies for distributed electrical propulsion aircraft

Electrically driven distributed propulsion has been presented as a possible solution to reduce aircraft noise and emissions, despite increasing global levels of air travel. In order to realise electrical propulsion, novel aircraft electrical systems are required. Since the electrical system must maintain security of power supply to the motors during flight, the protection devices employed on an electrical propulsion aircraft will form a crucial part of system design. However, electrical protection for complex aircraft electrical systems poses a number of challenges, particularly with regard to the weight, volume and efficiency constraints specific to aerospace applications. Furthermore, electrical systems will need to operate at higher power levels and incorporate new technologies, many of which are unproven at altitude and in the harsh aircraft environment. Therefore, today’s commercially available aerospace protection technologies are likely to require significant development before they can be considered as part of a fault management strategy for a next generation aircraft. By mapping the protection device trade space based on published literature to date, the discrepancy between the current status of protection devices and the target specifications can be identified for a given time frame. This paper will describe a process of electrical network design that is driven by the protection system requirements, incorporates key technology constraints and analyses the protection device trade space to derive feasible fault management strategies

A fault management oriented early-design framework for electrical propulsion aircraft

Electrical propulsion has been identified as a key enabler of greener, quieter, and more efficient aircraft. However, electrical propulsion aircraft (EPA) will need to demonstrate a level of safety and reliability at least equal to current aircraft to be a viable alternative. Therefore, a robust and reliable fault management (FM) system is needed to prevent electrical faults causing loss of propulsion and critical flight functions. To date, FM of the electrical propulsion system has not been considered in detail for future EPA, nor has it been effectively integrated into the electrical architecture design. This poses a risk that the proposed electrical architectures will be infeasible from an FM perspective, and key FM technologies may not be sufficiently developed. Therefore, a methodology to incorporate FM into the early stages of the design of electrical architectures is required to determine viable FM solutions for a given EPA concept. This paper describes a novel, system-level electrical architecture design framework for EPA, which incorporates FM from the outset. This methodology captures the significant assumptions in the design and acknowledges the novel interfaces that exist between the electrical, conceptual, and FM design of EPA

Protection and fault management strategy maps for future electrical propulsion aircraft

Electrical propulsion has been identified as a key enabler of greener, quieter, more efficient aircraft. However, electrical propulsion aircraft (EPA) will need to demonstrate a level of safety and fault management (FM) at least equal to current aircraft. This will rely heavily on the capability and design of the electrical FM system. Given the functional limitations and current lack of FM technologies suitable for a future EPA application, strategic development of FM devices is required. Whilst there are a variety of roadmaps for EPA concepts and key electrical components, the necessary development of FM solutions targeted towards EPA has yet to be established. This paper proposes FM strategy maps which go beyond projections of expected development in FM technologies to scope the feasibility of key FM solutions. This method can then be used to present FM technology projections, electrical oversizing and wider system redundancy alongside the EPA concepts in development. These strategy maps capture the impact of any FM technology barrier on the viability of a given EPA concept, enabling critical FM solutions to be integrated into the wider electrical system development. This marks a significant contribution to the development of robust, strategic electrical FM for future EPA concepts

Developing an Intervention for Fall-Related Injuries in Dementia (DIFRID): an integrated, mixed-methods approach

Background Falls in people with dementia can result in a number of physical and psychosocial consequences. However, there is limited evidence to inform how best to deliver services to people with dementia following a fall. The aim of the DIFRID study was to determine the feasibility of developing and implementing a new intervention to improve outcomes for people with dementia with fall-related injuries; this encompasses both short-term recovery and reducing the likelihood of future falls. This paper details the development of the DIFRID intervention. Methods The intervention was designed using an integrated, mixed-methods approach. This involved a realist synthesis of the literature and qualitative data gathered through interviews and focus groups with health and social care professionals (n=81). An effectiveness review and further interviews and observation were also conducted and are reported elsewhere. A modified Delphi panel approach with 24 experts was then used to establish a consensus on how the findings should translate into a new intervention. After feedback from key stakeholders (n=15) on the proposed model, the intervention was manualised and training developed. Results We identified key components of a new intervention covering three broad areas: • Ensuring that the circumstances of rehabilitation are optimised for people with dementia • Compensating for the reduced ability of people with dementia to self-manage • Equipping the workforce with the necessary skills and information to care for this patient group Consensus was achieved on 54 of 69 statements over two rounds of the Delphi surveys. The statements were used to model the intervention and finalise the accompanying manual and protocol for a feasibility study. Stakeholder feedback was generally positive and the majority of suggested intervention components were approved. The proposed outcome was a 12-week complex multidisciplinary intervention primarily based at the patient’s home. Conclusions A new intervention has been developed to improve outcomes for people with dementia following a fall requiring healthcare attention. The feasibility of this intervention is currently being tested. Trial registration ISRCTN41760734 (16/11/2015

An intervention to support stroke survivors and their carers in the longer term (LoTS2Care): study protocol for a cluster randomised controlled feasibility trial

Background Despite the evidence that many stroke survivors report longer term unmet needs, the provision of longer term care is limited. To address this, we are conducting a programme of research to develop an evidence-based and replicable longer term care strategy. The developed complex intervention (named New Start), which includes needs identification, exploration of social networks and components of problem solving and self-management, was designed to improve quality of life by addressing unmet needs and increasing participation. Methods/Design A multicentre, cluster randomised controlled feasibility trial designed to inform the design of a possible future definitive cluster randomised controlled trial (cRCT) and explore the potential clinical and cost-effectiveness of New Start. Ten stroke services across the UK will be randomised on a 1:1 basis either to implement New Start or continue with usual care only. New Start will be delivered by trained facilitators and will be offered to all stroke survivors within the services allocated to the intervention arm. Stroke survivors will be eligible for the trial if they are 4–6 months post-stroke and residing in the community. Carers (if available) will also be invited to take part. Invitation to participate will be initiated by post and outcome measures will be collected via postal questionnaires at 3, 6 and 9 months after recruitment. Outcome data relating to perceived health and disability, wellbeing and quality of life as well as unmet needs will be collected. A ‘study within a trial’ (SWAT) is planned to determine the most acceptable format in which to provide the postal questionnaires. Details of health and social care service usage will also be collected to inform the economic evaluation. The feasibility of recruiting services and stroke survivors to the trial and of collecting postal outcomes will be assessed and the potential for effectiveness will be investigated. An embedded process evaluation (reported separately) will assess implementation fidelity and explore and clarify causal assumptions regarding implementation. Discussion This feasibility trial with embedded process evaluation will allow us to gather important and detailed data regarding methodological and implementation issues to inform the design of a possible future definitive cRCT of this complex intervention. Trial Registration ISRCTN38920246. Registered 22 June 2016

The Science Performance of JWST as Characterized in Commissioning

This paper characterizes the actual science performance of the James Webb Space Telescope (JWST), as determined from the six month commissioning period. We summarize the performance of the spacecraft, telescope, science instruments, and ground system, with an emphasis on differences from pre-launch expectations. Commissioning has made clear that JWST is fully capable of achieving the discoveries for which it was built. Moreover, almost across the board, the science performance of JWST is better than expected; in most cases, JWST will go deeper faster than expected. The telescope and instrument suite have demonstrated the sensitivity, stability, image quality, and spectral range that are necessary to transform our understanding of the cosmos through observations spanning from near-earth asteroids to the most distant galaxies.Comment: 5th version as accepted to PASP; 31 pages, 18 figures; https://iopscience.iop.org/article/10.1088/1538-3873/acb29

Dolutegravir twice-daily dosing in children with HIV-associated tuberculosis: a pharmacokinetic and safety study within the open-label, multicentre, randomised, non-inferiority ODYSSEY trial

Background: Children with HIV-associated tuberculosis (TB) have few antiretroviral therapy (ART) options. We aimed to evaluate the safety and pharmacokinetics of dolutegravir twice-daily dosing in children receiving rifampicin for HIV-associated TB. Methods: We nested a two-period, fixed-order pharmacokinetic substudy within the open-label, multicentre, randomised, controlled, non-inferiority ODYSSEY trial at research centres in South Africa, Uganda, and Zimbabwe. Children (aged 4 weeks to <18 years) with HIV-associated TB who were receiving rifampicin and twice-daily dolutegravir were eligible for inclusion. We did a 12-h pharmacokinetic profile on rifampicin and twice-daily dolutegravir and a 24-h profile on once-daily dolutegravir. Geometric mean ratios for trough plasma concentration (Ctrough), area under the plasma concentration time curve from 0 h to 24 h after dosing (AUC0–24 h), and maximum plasma concentration (Cmax) were used to compare dolutegravir concentrations between substudy days. We assessed rifampicin Cmax on the first substudy day. All children within ODYSSEY with HIV-associated TB who received rifampicin and twice-daily dolutegravir were included in the safety analysis. We described adverse events reported from starting twice-daily dolutegravir to 30 days after returning to once-daily dolutegravir. This trial is registered with ClinicalTrials.gov (NCT02259127), EudraCT (2014–002632-14), and the ISRCTN registry (ISRCTN91737921). Findings: Between Sept 20, 2016, and June 28, 2021, 37 children with HIV-associated TB (median age 11·9 years [range 0·4–17·6], 19 [51%] were female and 18 [49%] were male, 36 [97%] in Africa and one [3%] in Thailand) received rifampicin with twice-daily dolutegravir and were included in the safety analysis. 20 (54%) of 37 children enrolled in the pharmacokinetic substudy, 14 of whom contributed at least one evaluable pharmacokinetic curve for dolutegravir, including 12 who had within-participant comparisons. Geometric mean ratios for rifampicin and twice-daily dolutegravir versus once-daily dolutegravir were 1·51 (90% CI 1·08–2·11) for Ctrough, 1·23 (0·99–1·53) for AUC0–24 h, and 0·94 (0·76–1·16) for Cmax. Individual dolutegravir Ctrough concentrations were higher than the 90% effective concentration (ie, 0·32 mg/L) in all children receiving rifampicin and twice-daily dolutegravir. Of 18 children with evaluable rifampicin concentrations, 15 (83%) had a Cmax of less than the optimal target concentration of 8 mg/L. Rifampicin geometric mean Cmax was 5·1 mg/L (coefficient of variation 71%). During a median follow-up of 31 weeks (IQR 30–40), 15 grade 3 or higher adverse events occurred among 11 (30%) of 37 children, ten serious adverse events occurred among eight (22%) children, including two deaths (one tuberculosis-related death, one death due to traumatic injury); no adverse events, including deaths, were considered related to dolutegravir. Interpretation: Twice-daily dolutegravir was shown to be safe and sufficient to overcome the rifampicin enzyme-inducing effect in children, and could provide a practical ART option for children with HIV-associated TB