Turboelectric Distributed Propulsion System for NASA Next Generation Aircraft

Next generation aircraft, more specifically NASA aircraft concepts, will include new technologies and make many advancements in fuel economy and noise. However, there are some challenges associated with the latest technologies that NASA is planning to use for the next generation aircraft. For example, these aircraft concepts require large amounts of electrical power to generate the required thrust throughout a notional flight profile. One of the new technologies is using advanced propulsion systems, such as the Turboelectric Distributed Propulsion (TeDP) system, which is significantly different from current aerospace high bypass turbofan based propulsion system. The TeDP propulsion system replaces the traditional turbofan engines with a series of embedded electrical fans. The blended wing body aircraft, N3-X (Boeing 777 class), that NASA proposed will have as many as 14 electric fans mounted on the upper aft surface of the aircraft wings. In addition to improved aircraft efficiency, this propulsion system change will significantly reduce noise generation, and provide the capability of short take-off and landing. A dynamic model of the ducted fan distributed propulsion system was developed and simulated for different notional flight profiles. The results show that the ducted fan distributed propulsion system dynamic model and the control system successfully generate the required thrust for the flights and capture the transient behavior of the system throughout the flight profiles. In addition, the dynamic model was used to model a 50 passenger regional aircraft. This study shows the benefit of both the TeDP system and the flexibility of the developed model. The contribution to knowledge is the evolution of the evaluation model that helps researcher\u27s understand propulsion systems such as the TeDP system of NASA N+3 class aircraft. By identifying and understanding the principal challenges and possibilities provided by the technology, this research further contributes to defining a roadmap of the new technology propulsion system for future research

Mortality from gastrointestinal congenital anomalies at 264 hospitals in 74 low-income, middle-income, and high-income countries: a multicentre, international, prospective cohort study

Summary Background Congenital anomalies are the fifth leading cause of mortality in children younger than 5 years globally. Many gastrointestinal congenital anomalies are fatal without timely access to neonatal surgical care, but few studies have been done on these conditions in low-income and middle-income countries (LMICs). We compared outcomes of the seven most common gastrointestinal congenital anomalies in low-income, middle-income, and high-income countries globally, and identified factors associated with mortality. Methods We did a multicentre, international prospective cohort study of patients younger than 16 years, presenting to hospital for the first time with oesophageal atresia, congenital diaphragmatic hernia, intestinal atresia, gastroschisis, exomphalos, anorectal malformation, and Hirschsprung’s disease. Recruitment was of consecutive patients for a minimum of 1 month between October, 2018, and April, 2019. We collected data on patient demographics, clinical status, interventions, and outcomes using the REDCap platform. Patients were followed up for 30 days after primary intervention, or 30 days after admission if they did not receive an intervention. The primary outcome was all-cause, in-hospital mortality for all conditions combined and each condition individually, stratified by country income status. We did a complete case analysis. Findings We included 3849 patients with 3975 study conditions (560 with oesophageal atresia, 448 with congenital diaphragmatic hernia, 681 with intestinal atresia, 453 with gastroschisis, 325 with exomphalos, 991 with anorectal malformation, and 517 with Hirschsprung’s disease) from 264 hospitals (89 in high-income countries, 166 in middleincome countries, and nine in low-income countries) in 74 countries. Of the 3849 patients, 2231 (58·0%) were male. Median gestational age at birth was 38 weeks (IQR 36–39) and median bodyweight at presentation was 2·8 kg (2·3–3·3). Mortality among all patients was 37 (39·8%) of 93 in low-income countries, 583 (20·4%) of 2860 in middle-income countries, and 50 (5·6%) of 896 in high-income countries (p<0·0001 between all country income groups). Gastroschisis had the greatest difference in mortality between country income strata (nine [90·0%] of ten in lowincome countries, 97 [31·9%] of 304 in middle-income countries, and two [1·4%] of 139 in high-income countries; p≤0·0001 between all country income groups). Factors significantly associated with higher mortality for all patients combined included country income status (low-income vs high-income countries, risk ratio 2·78 [95% CI 1·88–4·11], p<0·0001; middle-income vs high-income countries, 2·11 [1·59–2·79], p<0·0001), sepsis at presentation (1·20 [1·04–1·40], p=0·016), higher American Society of Anesthesiologists (ASA) score at primary intervention (ASA 4–5 vs ASA 1–2, 1·82 [1·40–2·35], p<0·0001; ASA 3 vs ASA 1–2, 1·58, [1·30–1·92], p<0·0001]), surgical safety checklist not used (1·39 [1·02–1·90], p=0·035), and ventilation or parenteral nutrition unavailable when needed (ventilation 1·96, [1·41–2·71], p=0·0001; parenteral nutrition 1·35, [1·05–1·74], p=0·018). Administration of parenteral nutrition (0·61, [0·47–0·79], p=0·0002) and use of a peripherally inserted central catheter (0·65 [0·50–0·86], p=0·0024) or percutaneous central line (0·69 [0·48–1·00], p=0·049) were associated with lower mortality. Interpretation Unacceptable differences in mortality exist for gastrointestinal congenital anomalies between lowincome, middle-income, and high-income countries. Improving access to quality neonatal surgical care in LMICs will be vital to achieve Sustainable Development Goal 3.2 of ending preventable deaths in neonates and children younger than 5 years by 2030

Turboelectric Distributed Propulsion System for NASA Next Generation Aircraft

Next generation aircraft, more specifically NASA aircraft concepts, will include new technologies and make many advancements in fuel economy and noise. However, there are some challenges associated with the latest technologies that NASA is planning to use for the next generation aircraft. For example, these aircraft concepts require large amounts of electrical power to generate the required thrust throughout a notional flight profile. One of the new technologies is using advanced propulsion systems, such as the Turboelectric Distributed Propulsion (TeDP) system, which is significantly different from current aerospace high bypass turbofan based propulsion system. The TeDP propulsion system replaces the traditional turbofan engines with a series of embedded electrical fans. The blended wing body aircraft, N3-X (Boeing 777 class), that NASA proposed will have as many as 14 electric fans mounted on the upper aft surface of the aircraft wings. In addition to improved aircraft efficiency, this propulsion system change will significantly reduce noise generation, and provide the capability of short take-off and landing. A dynamic model of the ducted fan distributed propulsion system was developed and simulated for different notional flight profiles. The results show that the ducted fan distributed propulsion system dynamic model and the control system successfully generate the required thrust for the flights and capture the transient behavior of the system throughout the flight profiles. In addition, the dynamic model was used to model a 50 passenger regional aircraft. This study shows the benefit of both the TeDP system and the flexibility of the developed model. The contribution to knowledge is the evolution of the evaluation model that helps researcher\u27s understand propulsion systems such as the TeDP system of NASA N+3 class aircraft. By identifying and understanding the principal challenges and possibilities provided by the technology, this research further contributes to defining a roadmap of the new technology propulsion system for future research