Multidisciplinary assessment of a year 2035 turbofan propulsion system

A conceptual design of a year 2035 turbofan is developed and integrated onto a year 2035 aircraft model. The mission performance is evaluated for CO2, noise and NOx and is compared with a notional XWB/A350-model. An OGV heat exchanger is then studied rejecting heat from an electric generator, and its top-level performance is evaluated. The fan, the booster and the low-pressure turbine of the propulsion system are subject to more detailed aero design based on using commercial design tools and CFD-optimization. Booster aerodynamic modelling output is introduced back into the performance model to study the integrated performance of the component. The top-level performance aircraft improvements are compared to top-level-trends and ICAO estimates of technology progress potential, attempting to evaluate whether there is some additional margin for efficiency improvement beyond the ICAO technology predictions for the same time frame

Ventilation Techniques and Risk for Transmission of Coronavirus Disease, Including COVID-19 A Living Systematic Review of Multiple Streams of Evidence

Background: Mechanical ventilation is used to treat respiratory failure in coronavirus disease 2019 (COVID-19). Purpose: To review multiple streams of evidence regarding the benefits and harms of ventilation techniques for coronavirus infections, including that causing COVID-19. (PROSPERO registration: CRD42020178187) Data Sources: 21 standard, World Health Organization–specific and COVID-19–specific databases, without language restrictions, until 1 May 2020. Study Selection: Studies of any design and language comparing different oxygenation approaches in patients with coronavirus infections, including severe acute respiratory syndrome (SARS) or Middle East respiratory syndrome (MERS), or with hypoxemic respiratory failure. Animal, mechanistic, laboratory, and preclinical evidence was gathered regarding aerosol dispersion of coronavirus. Studies evaluating risk for virus transmission to health care workers from aerosol-generating procedures (AGPs) were included. Data Extraction: Independent and duplicate screening, data abstraction, and risk of bias assessment (GRADE for certainty of evidence and AMSTAR 2 for included systematic reviews). Data Synthesis: 123 studies were eligible (45 on COVID-19, 70 on SARS, 8 on MERS), but only 5 studies (1 on COVID-19, 3 on SARS, 1 on MERS) adjusted for important confounders. A study in hospitalized patients with COVID-19 reported slightly higher mortality with noninvasive ventilation (NIV) than with invasive mechanical ventilation (IMV), but 2 opposing studies, 1 in patients with MERS and 1 in patients with SARS, suggest a reduction in mortality with NIV (very low-certainty evidence). Two studies in patients with SARS report a reduction in mortality with NIV compared with no mechanical ventilation (low-certainty evidence). Two systematic reviews suggest a large reduction in mortality with NIV compared with conventional oxygen therapy. Other included studies suggest increased odds of transmission from AGPs. Limitation: Direct studies in COVID-19 are limited and poorly reported. Conclusion: Indirect and low-certainty evidence suggests that use of NIV, similar to IMV, probably reduces mortality but may increase the risk for transmission of COVID-19 to health care workers

Direct electromagnetic actuation on high ratio gears

This document demonstrates a conceptual study, design and development of unconventional electromagnetic actuators for applications where a high torque over a limited part of a rotational turn is required. The unconventionality of the actuators is that the electromagnetic actuation is applied directly on a high ratio transmission gear such as a cycloid disc in a cycloid drive or a flex-spline in a harmonic drive. Furthermore, normal forces are intentionally used to displace and rotate a cycloid disc or deform a flex-spline instead of tangential forces, which are typically used when integrating conventional rotating machine driving a high ratio gear transmission. The conceptual study is based on a number of finite element models where the idea is first presented and followed by field and force analysis. A finite element static model is used to calculate the expected excitation versus the gear location. The gear location of the cycloid disc is defined by an eccentric origin and rotation angle while the flex-spline is defined by a deformation and rotation angle. The analysis of the integrated normal force actuator inside the harmonic drive demonstrates the challenging strain gearing action in terms of elasticity and magnetic saturation. The challenge with the cycloid drive is the electromagnetic action force direction compared to the desired mechanic reaction force direction that causes unnecessary inner load or even locks the gear mechanisms. A prototype machine with the maximized rotor eccentricity is used to characterize four different rolling and geared cycloid transmissions

Engineering considerations on skewing of an interior permanent magnet synchronous machine for parallel hybrid electric heavy vehicles

The focus of this paper is on investigating the influence of skewing on the torque production of an Interior Permanent Magnet Synchronous Machine (IPMSM). The machine is designed as a traction machine according to the requirements of a parallel hybrid electric commercial heavy vehicle. In order to meet the requirements, the machine is designed with a speed higher than that of the conventional powertrain and connected via a fixed speed reduction. To minimize the noise and wear in the gear reduction, it is desirable to keep the torque ripples in the machine to a minimum. The investigation is performed in the post processor of a 2D FE simulation tool. The outcome from the study is that skewing has higher influence on the fundamental torque when operating in field weakening compared to below base speed. This makes skewing questionable as a mean to reduce the torque ripple in an IPMSM traction machine. The simulation result is verified with measurements with good correlation

Costs, health effects and cost-effectiveness of alcohol and tobacco control strategies in Estonia.

Contains fulltext : 53722.pdf (publisher's version ) (Closed access)OBJECTIVE: To assess the population-level costs, effects and cost-effectiveness of different alcohol and tobacco control strategies in Estonia. DESIGN: A WHO cost-effectiveness modelling framework was used to estimate the total costs and effects of interventions. Costs were assessed in Estonian Kroon (EEK) for the year 2000, while effects were expressed in disability-adjusted life years (DALYs) averted. Regional cost-effectiveness estimates for Eastern Europe, were used as baseline and were contextualised by including country-specific input data. RESULTS: Increased excise taxes are the most cost-effective intervention to reduce both hazardous alcohol consumption and smoking: 759 EEK (euro 49) and 218 EEK (euro 14) per DALY averted, respectively. Imposing additional advertising bans would cost 1331 EEK (euro 85) per DALY averted to reduce hazardous alcohol consumption and 304 EEK (euro 19) to reduce smoking. Compared to WHO-CHOICE regional estimates, interventions were less costly and thereby more cost-effective in Estonia. CONCLUSIONS: Interventions in alcohol and tobacco control are cost-effective, and broad implementation of these interventions to upgrade current situation is warranted from the economic point of view. First priority is an increase in taxation, followed by advertising bans and other interventions. The differences between WHO-CHOICE regional cost-effectiveness estimates and contextualised results underline the importance of the country level analysis

Power Losses and Heat Extraction in a Stator with Directly Air-Cooled Laminated Windings

This paper explores and assesses power loss generation and heat extraction in a stator with directly air-cooled laminated winding. An electrical machine winding made of an electric conducting sheet, which have slotted structure for accommodating a magnetic core, is denoted a laminated winding. A space is introduced between the conducting sheets so that the heating power is removed right where it is created. Explicit to the laminated windings, the conductors with smallest cross section and highest dc resistance have also limited cooling. Since these conductors are closest to the air-gap they become subject to induced power losses. An electrical machine with folded air-cooled laminated winding is built and evaluated. The paper demonstrates on how the thermal management of the stator segments is evaluated and adjusted during the manufacturing process. The power loss estimation of the prototype machine reveals significant discrepancy between the measurements and the calculation of known power losses at no load condition compared to short-circuit conditions. Conjugate heat transfer models are developed to evaluate the coolant flow distribution and heat dissipation in the direct air-cooled laminated windings

Direct Conductor Cooling in Concentrated Windings

This paper presents and assesses the cooling integration of electrical machines with concentrated windings. A conventional coil in a concentrated winding with forced cooling applied on the exterior coil surfaces is replaced by an alternative solution where the coil is opened up in a laminar structure with the intention of the coolant fluid penetrating the coil and removing the interior heat. This is a purely theoretical study where a set of FE models are used to evaluate the torque capability under elevated thermal loads, comparing conventional to alternative cooling integration topologies. The objective of the unsophisticated FE evaluation models and simple design rules is to demonstrate the potential of the laminated type of windings where the space between the current carrying flat conductors is used to circulate coolant so that the heat losses are removed in the vicinity of where they are generated. Conjugate heat transfer analysis in Comsol multiphysics based on 2D and 3D is used to demonstrate the cooling capability for air and oil cooled windings up to thermal loads corresponding to 50 A/mm2at 24 nΩm and a target hot spot temperature of 120°C for copper