A review of Turboelectric Distributed Propulsion technologies for N+3 aircraft electrical systems

In order to minimise the environmental impact of increased air traffic substantial developments in civil aircraft electrical power systems must occur. NASA have set a target to reduce noise by 71dB, NOx emissions by 80% and fuel consumption by 60% for the N+3 generation of aircraft entering into service sometime between 2030 and 2035. Turboelectric Distributed Propulsion (TeDP) is expected to enable these goals to be met. NASA's N3-X concept aircraft comprises gas turbine engines which drive electrical generators and a DC network distributes power to an array of fans, which provide thrust. Interconnection and protection technologies will also be included to achieve desired levels of reliability of supply to the propulsion motors. This paper outlines the architecture of a generic TeDP system, explores its benefits, describes technical challenges that will need to be overcome and discusses the technical implications of implementing TeDP with regards to electrical system power density and safety

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

Comparison of candidate architectures for future distributed propulsion aircraft

Turbine engine driven distributed electrical aircraft power systems (also referred to as Turboelectric Distributed Propulsion (TeDP)) are proposed for providing thrust for future aircraft with superconducting components operating at 77K in order for performance and emissions targets to be met. The proposal of such systems presents a radical change from current state-of-the-art aero-electrical power systems. Central to the development of such power systems are architecture design trades which must consider system functionality and performance, system robustness and fault ride-through capability, in addition to the balance between mass and efficiency. This paper presents a quantitative comparison of the three potential candidate architectures for TeDP electrical networks. This analysis provides the foundations for establishing the feasibility of these different architectures subject to design and operational constraints. The findings of this paper conclude that a purely AC synchronous network performs best in terms of mass and efficiency, but similar levels of functionality and controllability to an architecture with electrical decoupling via DC cannot readily be achieved. If power electronic converters with cryocoolers are found to be necessary for functionality and controllability purposes, then studies show that a significant increase in the efficiency of solid state switching components is necessary to achieve specified aircraft performance targets

Development of voltage standards for turbo-electric distributed propulsion aircraft power systems

Distributed propulsion is being considered as a possible solution to increase aircraft efficiency, reduce fuel costs and reduce emissions. The size, weight and efficiency of components within a Turbo-electric Distributed Propulsion (TeDP) system are dependent on the voltage level of the electrical power network. Current aircraft voltage standards do not address the architecture of distributed propulsion and so a review of voltage standards from different industries is conducted with areas of commonality addressed. An example of TeDP architecture is presented and analyzed to highlight how current aircraft standards may not apply to TeDP. A summary of challenges in developing standards for a TeDP is compiled with a stakeholder analysis to demonstrate the wide range of industries and personnel with vested interests in the development of voltage standards and recommended practices for TeDP

Lesbian and bisexual women's gynaecological conditions: a systematic review and exploratory meta-analysis

Background: Little is known about the gynaecological health of lesbian and bisexual (LB) women. Objectives: To examine differences in incidence and/or prevalence of gynaecological conditions in LB compared with heterosexual women. Search strategy: The systematic review protocol was prospectively registered (PROSPERO-CRD42015027091) and searches conducted in seven databases. Selection criteria: Comparative studies published 2000–2015, reporting any benign (non-infectious) and/or malignant gynaecological conditions with no language or setting restrictions. Data collection and analysis: Inclusions, data extraction and quality assessment were conducted in duplicate. Meta-analyses of condition prevalence rates were conducted where ≥3 studies reported results. Main results: From 567 records, 47 full papers were examined and 11 studies of mixed designs included. No studies directly addressing the question were found. Two chronic pelvic pain studies reported higher rates in bisexual compared with heterosexual women (38.5 versus 28.2% and 18.6 versus 6.4%). Meta-analyses showed no statistically significant differences in polycystic ovarian syndrome, endometriosis and fibroids. There was a higher rate of cervical cancer in bisexual than heterosexual women [odds ratio (OR) = 1.94; 95% CI 1.46–2.59] but no difference overall (OR = 0.76; 95% CI 0.15–3.92). There was a lower rate of uterine cancer in lesbian than heterosexual women (OR = 0.28; 95% CI 0.11–0.73) and overall (OR = 0.36; 95% CI 0.13–0.97), but no difference in bisexual women (OR = 0.43; 95% CI 0.06–3.07). Conclusions: More bisexual women may experience chr onic pelvic pain and cervical cancer than heterosexual women. There is no information on potential confounders. Better evidence is required, preferably monitoring sexual orientation in research using the existing validated measure and fully reporting results

Electronic screening for mental illness in patients with psoriasis

In this cross sectional study from a large UK centre, screening for mental illness in individuals with psoriasis has demonstrated a high burden of depression and anxiety. 85% of the cohort report that their psoriasis had affected their quality of life. Quality of life scores correlate with depression scores, emphasing the importance of managing individual's mental health alongside their psoriasis to improve overall quality of life

Reliability of Medical Records in Diagnosing Inflammatory Breast Cancer in Egypt

BACKGROUND: Inflammatory breast cancer (IBC) is a rare, aggressive breast cancer diagnosed clinically by the presence of diffuse erythema, peau d\u27orange, and edema that arise quickly in the affected breast. This study evaluated the validity of medical records in Gharbiah, Egypt in identifying clinical signs/symptoms of IBC. For 34 IBC cases enrolled in a case-control study at the Gharbiah Cancer Society and Tanta Cancer Center, Egypt (2009-2010), we compared signs/symptoms of IBC noted in medical records to those recorded on a standardized form at the time of IBC diagnosis by clinicians participating in the case-control study. We calculated the sensitivity and specificity of medical records as compared to the case-control study for recording these signs/symptoms. We also performed McNemar\u27s tests. RESULTS: In the case-control study, 32 (94.1%) IBC cases presented with peau d\u27orange, 30 (88.2%) with erythema, and 31 (91.2%) with edema. The sensitivities of the medical records as compared to the case-control study were 0.8, 0.5, and 0.2 for peau d\u27orange, erythema, and edema, respectively. Corresponding specificities were 1.0, 0.5, and 1.0. p values for McNemar\u27s test were CONCLUSION: Medical records lacked information on signs/symptoms of IBC, especially erythema and edema, when compared to the case-control study. Deficient medical records could have implications for diagnosis and treatment of IBC and proper documentation of cases in cancer registries

Impact of bottle size on in-home consumption of wine: feasibility and acceptability randomised cross-over study

Abstract: Background: Reducing alcohol consumption across populations would prevent many non-communicable diseases. Large packages increase food and non-alcoholic drink consumption and large glasses increase wine consumption. Smaller bottles may reduce alcohol consumption but their impact is uncertain. This study aims to (i) explore the feasibility and acceptability of conducting a large-scale randomised study to assess the impact of bottle size on in-home wine consumption and (ii) estimate the effect size and variance of the intervention on consumption to inform the design of future studies. Methods: Cross-over randomised study in which 16 households in Cambridge, England, consuming at least two 750-ml bottles of wine each week, received a pre-set volume of wine biweekly for 4 weeks, in 750-ml and 375-ml bottles, in random order. Consumption was assessed by recording the number of empty and partially full bottles at the end of each biweekly period. At the end of the study, household representatives were interviewed about their experiences of participating in the study. Results: The study procedures proved feasible. Comparable to similar trials, 14% of identified eligible households (18/125) consented to participate in the study. Attrition between consent and study completion was 11% (2/18) and 0% between study periods and 13% of households (2/16) correctly identified the study aim. The study procedures were considered acceptable. After adjusting for guest and out-of-home consumption, the difference in consumption between the 750-ml (3385.2 ml; SD = 1698.5) and 375-ml bottles (3376.7 ml; SD = 1719.0) was 8.4 ml (SD = 1235.4; 95%CI − 596.9, 613.8). Results suggest a possible order effect, with households receiving the 375-ml bottles first consuming more wine out of the 750-ml bottles and vice versa. This might also reflect an increase in consumption with study duration. Households receiving the 375-ml bottles first (6315.9 ml; SD = 3293.5) also drank less wine overall than those receiving the 750-ml bottles first (7335.4 ml; SD = 3735.4). Discussion: The findings support the feasibility and acceptability of running a large-scale randomised study to assess the impact of bottle size on in-home wine consumption. Due to the heterogeneous patterning of results, a future study will be powered using the variance observed in the current study to detect a meaningful reduction of 250 ml of wine when consumed from smaller compared with larger bottles. Trial registration: Open Science Framework (OSF): rmk43; May 23, 2017