H2020 STRATOFLY Project: from Europe to Australia in less than 3 hours

As eluded in previous studies, with special reference to those carried out in the European framework, some innovative high-speed aircraft configurations have now the potential to assure an economically viable high-speed aircraft fleet. They make use of unexploited flight routes in the stratosphere, offering a solution to the presently congested flight paths while ensuring a minimum environmental impact in terms of emitted noise and green-house gases, particularly during stratospheric cruise. However, only a dedicated multi-disciplinary integrated design approach could realize this, by considering airframe architectures embedding the propulsion systems as well as meticulously integrating crucial subsystems. In this context, starting from an in-depth investigation of the current status of the activities, the STRATOFLY project has been funded by the European Commission, under the framework of Horizon 2020 plan, with the aim of assessing the potential of this type of high-speed transport vehicle to reach Technology Readiness Level (TRL) 6 by 2035, with respect to key technological, societal and economical aspects. This paper aims at summarizing the main results achieved so far to solve the main issues related to thermal and structural integrity, low-emissions combined propulsion cycles, subsystems design and integration, including smart energy management, environmental aspects impacting climate change, noise emissions and social acceptance, and economic viability accounting for safety and human factors

Global disparities in surgeons’ workloads, academic engagement and rest periods: the on-calL shIft fOr geNEral SurgeonS (LIONESS) study

: The workload of general surgeons is multifaceted, encompassing not only surgical procedures but also a myriad of other responsibilities. From April to May 2023, we conducted a CHERRIES-compliant internet-based survey analyzing clinical practice, academic engagement, and post-on-call rest. The questionnaire featured six sections with 35 questions. Statistical analysis used Chi-square tests, ANOVA, and logistic regression (SPSS® v. 28). The survey received a total of 1.046 responses (65.4%). Over 78.0% of responders came from Europe, 65.1% came from a general surgery unit; 92.8% of European and 87.5% of North American respondents were involved in research, compared to 71.7% in Africa. Europe led in publishing research studies (6.6 ± 8.6 yearly). Teaching involvement was high in North America (100%) and Africa (91.7%). Surgeons reported an average of 6.7 ± 4.9 on-call shifts per month, with European and North American surgeons experiencing 6.5 ± 4.9 and 7.8 ± 4.1 on-calls monthly, respectively. African surgeons had the highest on-call frequency (8.7 ± 6.1). Post-on-call, only 35.1% of respondents received a day off. Europeans were most likely (40%) to have a day off, while African surgeons were least likely (6.7%). On the adjusted multivariable analysis HDI (Human Development Index) (aOR 1.993) hospital capacity > 400 beds (aOR 2.423), working in a specialty surgery unit (aOR 2.087), and making the on-call in-house (aOR 5.446), significantly predicted the likelihood of having a day off after an on-call shift. Our study revealed critical insights into the disparities in workload, access to research, and professional opportunities for surgeons across different continents, underscored by the HDI

Analysis of a combined cycle propulsion system for STRATOFLY hypersonic vehicle over an extended trajectory

Hypersonic civil aviation is an important enabler for extremely shorter flight durations for long-haul routes and using unexploited flight altitudes. Combined cycle engine concepts providing extended flight capabilities, i.e. propelling the aircraft from take-off to hypersonic speeds, are proposed to achieve high-speed civil air transportation. STRATOFLY project is a continuation of former European efforts in hypersonic research and aims at developing a commercial reusablevehicle for cruise speed of Mach 8 at stratospheric altitudes as high as 35 km above ground level. The propulsion plant of STRATOFLY aircraft consists of combination of two different type of engines: an array of air turbo rockets and a dualmode ramjet/scramjet. In the present study, 1D transient thermodynamic simulations for this combined cycle propulsion plant have been conducted between Mach 0 to 8 by utilizing 1D inviscid flow transport relations, numerical tools availablein EcosimPro software platform and the European Space Propulsion System Simulation libraries. The optimized engine parameters are achieved by coupling EcosimPro software with Computer Aided Design Optimization which is a differential evolution algorithm developed at the von Karman Institute

Reduced order design and investigation of intakes for high speed propulsion systems

Ramjet propulsion is commonly preferred to power supersonic and hypersonic vehicles for cruising faster than Mach 3. This is an elegant solution owing to the lean architecture which does not embody any rotating parts. Although the geometry of the engine is simple as compared to turbine based configurations, the flow physics through the engine duct is quite complex and the flow speeds modulate between the supersonic and subsonic regimes multiple times. The design and performance analysis of ramjet engines are vital to ensure that propulsion system can satisfy the flight trajectory requirements. Therefore, this study introduces a reduced order holistic approach for design and assessment of the flow development in high-speed propulsion systems composed of generic elements of ramjet/scramjet engine configurations. Accordingly, the intakes designed based on axisymmetric flow templates are used to provide the necessary freestream flow modulation prior to the isolator through which a normal shock assumption is applied. The resultant flow properties are utilized for the combustion module where the flow expansion within the combustor and nozzle components are computed based on 1D steady inviscid flow equations coupled with detailed chemistry approach and JANAF tables. The module was validated and verified with the experimental and numerical data obtained for a dual-mode ramjet/scramjet combustor. Consequently, the parameters such as thrust, fuel consumption and specific impulse are calculated to quantify the engine performance for each design. Finally, the employment of the low fidelity model is demonstrated over a family of ramjet flow paths where the design space is confined based on the requirements of a high-supersonic cruise vehicle

Thermodynamic efficiency analysis and investigation of exergetic effectiveness of STRATOFLY aircraft propulsion plant

info:eu-repo/semantics/publishe

Reduced order design space analysis of for ramjet engines with data mining techniques

info:eu-repo/semantics/publishe

Reduced-order modeling of supersonic fuel–air mixing in a multi-strut injection scramjet engine using machine learning techniques

Dual-mode ramjet/scramjet engines promise extended flight speed range and are the commonly preferred air-breathing propulsion system from within the family of hypersonic aircraft concepts. One of the main challenges that should be hurdled in their design is modeling the fuel–air mixing process to provide optimal fuel distribution and yield the best engine performance. Injecting fuel into high-speed air stream along multiple parallel struts can augment the fuel penetration and improve mixing efficiency. Mixing intensity is increased with turbulence by the shock-expansion waves in post-strut regions. However, this enhancement in mixing can bring about detrimental effects on the aerodynamic performance by increasing losses on total pressure. Designing the optimal working configuration requires testing the interaction between many design variables. This can be a tedious and computationally costly task. Machine learning models thus appear well-suited for multi-objective optimization of design variables that can be elusive to designers. In particular, non-linear regression models can be built over the available sparse simulation data to predict unseen mixing conditions. In the present work, we carry out a detailed investigation of the effect of multi-strut configuration parameters on three objective functions: mixing efficiency, mixing length, and the total pressure recovery (TPR) factor. These objective functions are linked with the most relevant physical phenomena in the supersonic fuel–air mixing flow field. We first generate a CFD database by solving compressible, non-reactive, Reynolds-averaged Navier–Stokes (RANS) filtered flow equations in a 2D scramjet engine domain with three varying design variables: struts location, strut wedge angle and strut V-settlement angle. We then apply various regression models – artificial neural network (ANN), Gaussian process regression (GPR), and kernel regression – to this database and formulate a surrogate model relevant for fuel injection that can be utilized in reduced-order modeling studies that estimate the hypersonic engine performance. We find that regression is generally more difficult in the vicinity of fuel struts (due to turbulence/shock effects) and easier further downstream from the struts, but ANN performs generally better than other regression models. Thus, our reduced-order tool incorporates a mixing efficiency model predicted by the ANN. It computes the thrust of a hypersonic engine with less than 10% error. We also present a detailed discussion of the physical insights gained from our CFD database; we link this discussion with the earlier findings from the machine learning tools. In our sensitivity study, we find the strut wedge angle to be the most influencing parameter on the mixing properties and aerodynamic losses.info:eu-repo/semantics/publishe

An algorithm for Botulinum toxin A injection for upper eyelid retraction associated with thyroid eye disease: long-term results

Purpose To evaluate the efficacy and complications of transconjunctival Botulinum toxin A injections performed according to an algorithm, for the management of upper eyelid retraction associated with thyroid eye disease

Strategies for preliminary re-design of a LH2 Mach 5 cruiser concept originally conceived for Mach 8 mission

This paper aims at presenting some aircraft design activities currently carried out in the framework of the H2020 MORE&LESS project. Specifically, benefitting of the latest outcomes of the H2020 STRATOFLY project, POLITO, CIRA and VKI are currently working at the re-design of the original Mach 8 waverider (MR3 vehicle concept) to derive a sustainable Mach 5 vehicle and mission concept. This paper presents the preliminary re-design of the Mach 5 waverider concept (MR5), keeping the same vehicle configuration and the same propulsive technologies (operating in different modes). The envisaged multidisciplinary methodology is here reported, focusing on the unavoidable links among aircraft and mission design, subsystems integration, aerothermodynamics and propulsion. First, the same configuration of the MR3 vehicle is considered, to evaluate the best solution in terms of propellant mass to be stored on-board. Then, a preliminary study on the possible modifications of the air-intake, to improve its performance in the supersonic range, is presented. Each configuration is validated through mission analysis. The capability to perform the Mach 5 mission is verified. However, further steps are needed to move towards a scaling down of the MR3 vehicle, while keeping the overall shape and proportion of the vehicle unchanged, to allow for a full exploitation of the outcomes of the STRATOFLY project

H2020 STRATOFLY project: from Europe to Australi in less than 3 hours

International audienceAs eluded in previous studies, with special reference to those carried out in the European framework, some innovative high-speed aircraft configurations have now the potential to assure an economically viable highspeed aircraft fleet. They make use of unexploited flight routes in the stratosphere, offering a solution to the presently congested flight paths while ensuring a minimum environmental impact in terms of emitted noise and greenhouse gases, particularly during stratospheric cruise. However, only a dedicated multidisciplinary integrated design approach could realize this, by considering airframe architectures embedding the propulsion systems as well as meticulously integrating crucial subsystems. In this context, starting from an in-depth investigation of the current status of the activities, the STRATOFLY project has been funded by the European Commission, under the framework of Horizon 2020 plan, with the aim of assessing the potential of this type of high-speed transport vehicle to reach Technology Readiness Level (TRL) 6 by 2035, with respect to key technological, societal and economical aspects. This paper aims at summarizing the main results achieved so far to solve the main issues related to thermal and structural integrity, low-emissions combined propulsion cycles, subsystems design and integration, including smart energy management, environmental aspects impacting climate change, noise emissions and social acceptance, and economic viability accounting for safety and human factors