bluuebunny/crossref_metadata_2025 huggingface dataset:
Taming chaos in generalized Liénard systems by the fractional-order feedback based on Melnikov analysis
Authors: Li Ruihong , Li Qinnan , Huang Dongmei
Published: June 2023

The dynamical behavior of Liénard systems has always been a hot topic in nonlinear analysis. In the present study, a simple fractional-order feedback controller is put forward to tame chaos for a class of forced generalized Liénard systems. Adopting harmonic balance method, the first-order approximate equivalent integer-order system of the original fractional-order system is deduced. Then the criterion for taming chaos is established by employing the Melnikov approach. Duffing-Rayleigh chaotic oscillator is taken as an example to illustrate the validity of the proposed method. Firstly, the critical feedback intensity and differential order for taming chaos are obtained by the proposed criterion. Then, multiple numerical indicators such as phase portrait, time history plot, Lyapunov exponent and bifurcation diagram are provided to assist in analyzing theoretical results.
Optical response properties of a hybrid optomechanical system with quantum dot molecules assisted by second-order optomechanical coupling
Authors: Mahajan Sonam , Aggarwal Neha , Bhattacherjee Aranya B
Published: June 2023

We theoretically investigated the optical response properties of the optical field in three-level quantum dot molecules assisted optomechanical system consisting of the mechanical resonator. We show that various system parameters like second-order optomechanical coupling can control these nonlinear effects. In this work, we study how the system parameters affect the normal mode splitting of the movable mirror and output field. Further, we show that the second-order optomechanical coupling plays an important role in creating optomechanical entanglement as well as producing a strong squeezing spectrum of the optical field.
Effusion of stochastic processes on a line
Authors: Dean David S , Majumdar Satya N , Schehr Grégory
Published: June 2023

We consider the problem of leakage or effusion of an ensemble of independent stochastic processes from a region where they are initially randomly distributed. The case of Brownian motion, initially confined to the left half line with uniform density and leaking into the positive half line is an example which has been extensively studied in the literature. Here we derive new results for the average number and variance of the number of leaked particles for arbitrary Gaussian processes initially confined to the negative half line and also derive its joint two-time probability distribution, both for the annealed and the quenched initial conditions. For the annealed case, we show that the two-time joint distribution is a bivariate Poisson distribution. We also discuss the role of correlations in the initial particle positions on the statistics of the number of particles on the positive half line. We show that the strong memory effects in the variance of the particle number on the positive real axis for Brownian particles, seen in recent studies, persist for arbitrary Gaussian processes and also at the level of two-time correlation functions.
Nonergodic Brownian oscillator: low-frequency response
Authors: Plyukhin Alex V
Published: June 2023

An undisturbed Brownian oscillator may not reach thermal equilibrium with the thermal bath due to the formation of a localized normal mode. The latter may emerge when the spectrum of the thermal bath has a finite upper bound ω
0 and the oscillator natural frequency exceeds a critical value

ω

c

, which depends on the specific form of the bath spectrum. We consider the response of the oscillator with and without a localized mode to the external periodic force with frequency Ω lower than ω
0. The results complement those obtained earlier for the high-frequency response at

Ω
⩾

ω
0

and require a different mathematical approach. The signature property of the high-frequency response is resonance when the external force frequency Ω coincides with the frequency of the localized mode

ω
∗

. In the low-frequency domain

Ω
<

ω
0

the condition of resonance

Ω
=

ω
∗

cannot be met (since

ω
∗

>

ω
0

). Yet, in the limits

ω
→

ω

c

and

Ω
→

ω
0
−

, the oscillator shows a peculiar quasi-resonance response with an amplitude increasing with time sublinearly.
Multidisciplinary design of aircraft wing for multiregime purposes
Authors: Hospodář P , Drábek A
Published: June 2023

In this paper optimization process of the geometrical design of the wing is described. The goal is to minimize the aerodynamic drag at a requested lift in the cruise regime and thus reduce the fuel consumption. The second goal is to ensure the requested landing regime of the aircraft. Both cases are solved under the wing structural and weight considerations. As a fast design computational tool, a lifting line theory is used. It is moreover supplemented by non-linear aerodynamic airfoil characteristics to provide more accurate results of aerodynamic drag of the wing. These airfoil data were calculated with the CFD and enables to take significant accuracy between low and high-fidelity method which is verified in previous work. The list of requirements is set for aircraft for 40 passengers with a range of 2,500 km at a speed of 438 km/h. As the baseline the L-610 aircraft is selected. Optimized wing geometry in verified in cruise and landing regime/configuration with CFD solver. From the calculation of the weight of the wing and CFD results, the flight performance is calculated for the desired flight mission.
Novel active control technique of aircraft flaps asymmetry
Authors: Baldo L , Cejudo Ruiz J. M. , Dalla Vedova M D L
Published: June 2023

This paper proposes an active monitoring strategy to control aircraft trailing-edge high-lift devices (flaps) asymmetry. A variety of system failures can cause asymmetry in the control surfaces, including the transmission torsion bar break down and control surface actuator wear and tear. The authors’ novel asymmetry active monitoring approach detects and identifies flaps position asymmetry. Once the failure side has been identified, the active control activates the wingtip brakes to stop the uncontrolled flap surface. The still controlled flaps are driven to the damaged surface braking point to reduce flap asymmetry. As a result, the undesired aircraft roll moment (due to flaps asymmetry) will be controlled, and the aircraft maneuverability after failure will be (partially) restored. The proposed asymmetry active monitoring technique has been widely tested in different operational and failure conditions, using wear-free or worn-out actuators and considering every failure side scenario. The behavior of the proposed active model is evaluated in terms of time response and stability margin under certain operating conditions.
Sizing Approach with Flight Time Comparison of An Electric Multirotor Propulsion Chain with Batteries and Fuel Cells
Authors: Chahba S , Sehab R , Krebs G , Akrad A , Morel C
Published: June 2023

The concept of electric vertical take-off and landing (E-VTOL) aerial vehicles is gaining more and more attention, thanks to their non-polluting operation and simple air traffic management. Indeed, around the world, there are currently more than 500 projects that concern the development and improvement of their performances. Development of sizing methods for rapid selection of the propulsion chain components remains an important task in this process. In this paper, an approach for sizing and selecting the propulsion chain components of an E-VTOL aerial vehicle is developed and validated. First, the optimal pair motor/propeller is selected using a global nonlinear optimization in order to maximize the specific efficiency of these components. Second, two energy storage technologies are considered and sized in order to assess their influence on the aerial vehicle flight time. Finally, based on this sizing process, the optimized propulsion chain gross take-off weight (GTOW) is evaluated, using regression methods based on propulsion chain supplier data.
Deriving a year 2040 reference aircraft from a modern turboprop, implemented and calibrated in SUAVE
Authors: Brenner F , Mangold J , Eisenhut D , Moebs N , Strohmayer A
Published: June 2023

The FUTPRINT50 project is focused on designing and preparing ground for a hybrid-electric regional aircraft with a capacity of 50 passengers. The aircraft is designed for entry-into-service between 2035 and 2040. To evaluate and refine the design concepts, the project will use two different reference aircraft: one that is state-of-the-art, and another that is extrapolated to represent what a year 2040 model might look like. The ATR 42-500, a 50-seat aircraft with a design range of 840 nautical miles, will serve as the year 2000 reference aircraft. As part of the project, the open-source aircraft design tool SUAVE is adapted for use with hybrid-electric aircraft. The ATR 42-500 was reverse-engineered in the same SUAVE environment using official manufacturer data and other sources for reference and calibration. The environmental impact of the aircraft is assessed based on its emissions of CO2, NOX, and noise. The technology used in the ATR 42-500 will be outdated by 2040. To estimate the impact of the year 2035/2040 hybrid components, a year 2040 reference aircraft was implemented. This aircraft is based on the ATR 42-500 but will incorporate several further enhanced technologies, such as a higher wing aspect ratio, more efficient engines, and improved materials.
Regional Multi-Mission Aircraft in Clean Sky 2: Environmental Impact and Actual Technologies Evaluation from Flight Tests
Authors: Benítez Luis , Martinez Miguel , Nuñez Manuel
Published: June 2023

Airbus Defence and Space, former CASA, has lead the Regional Multi-mission aircraft configuration in the Clean Sky 2 program. The set of technologies selected for this platform have been matured with the support of multiple partners across Europe by means of theoretical studies, tests in laboratories, full scale on ground demonstration in rigs and in flight demonstration in the Regional Flight Test Bed 2 (FTB#2) platform based on an Airbus C295 aircraft. These technologies cover multiple aspects of the aircraft design, manufacturing and operations like innovative materials, systems architectures towards a more electrical aircraft, affordable flight control system devoted to control multiple control surfaces in the wing and new manufacturing and assembly processes. The outputs of the research are taken to evaluate the environmental impact in terms of gaseous emissions (fuel consumption, CO2 and NOx) and noise reduction in take-off and landing of future aircraft with respect of the reference configuration defined at the beginning of Clean Sky 2 program. This paper describes the environmental impact in future Regional Multi-mission configurations and the technology evaluation done with the flight test campaign of the Regional FTB#2 in 2022. The flight test campaign is a cornerstone milestone of the program to demonstrate the most mature technologies.
Preliminary design of next generation Mach 1.6 supersonic business jets to investigate landing & take-off (LTO) noise and emissions – SENECA.
Authors: Mourouzidis C , Del Gatto D , Adamidis S , Villena Munoz C , Lawson C , Martinez Corzo B , Leyland P , Marsh D , Lim L , Owen B , Terrenoire E , Atinault O , LeGriffon I. , Huet M , Schaefer M , Plohr M , Bake S , Madden P
Published: June 2023

With the approach of next generation supersonic transport entry into service, new research activities were initiated to support updates on ICAO regulations and certification processes for supersonic transport vehicles. Within this context, the EU Horizon 2020 SENECA project has been launched to investigate the levels of noise and gaseous emissions in the vicinity of airports as well as the global climate impact of next generation supersonic civil aircraft. This paper introduces some of the preliminary outcomes of this investigation. It presents the preliminary design and performance analysis of a Mach 1.6 business jet, following an integrated aircraft-engine design approach. The preliminary design was performed accounting for the limitations posed by future environmental restrictions on respective subsonic vehicles. The market space and mission route definition exercise assumed only “over-sea” supersonic operations, while for “over-land”, only subsonic operations where allowed. Parametric studies on engine integrated design demonstrated modest core temperatures while cruising and the significant impact of engine installation on performance. At this first design iteration, assuming current state of the art technology, the Mach 1.6 business jet showed good potential to satisfy the predicted mission requirements while respecting the environmental constraints in terms of Landing & Take-Off (LTO) noise and emissions.
Environmental-impact assessments at airport level of Clean Sky 2 technologies
Authors: van Eenige M J A , van Ommeren T E
Published: June 2023

GREENPORT2050 is a project within Clean Sky 2 Technology Evaluator. Its objective is to assess the environmental impact up to 2050 at airport level of technologies developed in the Clean Sky 2 Programme for fixed-wing aircraft. With these assessments, it complements the environmental-impact assessments of those technologies at the other two levels in Clean Sky 2 Technology Evaluator: aircraft and air-transport system level. This paper provides an overview of the systematic approach for airport-level assessments in GREENPORT2050 and of the indicators to quantify impacts in these assessments.
CO2 and non-CO2 balanced Environmental Scores Module for flight performance evaluation and optimisation
Authors: Middel Jan , Sutopo Kinanthi , Heesbeen Bart , Verbeek René , Dungen Nick van den , Sáez Raúl , Prats Xavier , Riccio Angelo
Published: June 2023

The SESAR2020 exploratory research (ER4) programme CREATE (Grant 890898) developed a climate and weather aware Concept of Operations (ConOps) which encompasses a multi-aircraft 4D trajectory optimisation framework, which utilises a CO2 and non-CO2 balanced Environmental Scores Module (ESM) for the en-route flight phase. The ESM provides a computational method to evaluate the “greenness” of aircraft trajectories. Some components related to the internal ESM scoring are based on expert judgement, which is in line with the technology readiness level (TRL) 1 of the solution. Fast-time simulations were performed to demonstrate the proof-of-concept of the ESM in a multi-aircraft tactical optimisation scenario in the North-Atlantic region. The results show that, because of the simplicity of the metric, the ESM could be well used for trajectory optimisation and tactical replanning, and most likely as well as flight and ATC sector environmental performance evaluations.
Operating and Environmental Cost Considerations Comparison for Hybrid-Electric Propulsion Architecture Variants
Authors: Nasoulis Christos P. , Protopapadakis Georgios , Ntouvelos Elissaios G. , Gkoutzamanis Vasilis G. , Kalfas Anestis I.
Published: June 2023

A promising solution for sustainable aviation is hybrid-electric propulsion, which is gaining popularity in recent years. However, hybrid-electric propulsion variants are affected by the technological maturity of electric components, which have a direct impact on the electrification benefit, compared to conventional propulsive configurations. This work aims in investigating three different Entry Into Service dates, i.e., 2027, 2030, and 2040, for two hybrid-electric propulsive configurations, namely the Series and the Parallel. Six hybrid variants are sized, one for each date and configuration, using an in-house tool, and their mission performance metrics, operating costs, and environmental impact are compared to a conventional aircraft with technological assumptions of 2014. Results indicate that the Parallel variants promise a block fuel and energy reduction of up to 33 % and 28 % respectively for 2040, whereas the Series variants show a respective reduction of 66 % and 58 % accordingly. Moreover, the 2027 Parallel aircraft has reduced annual operating costs compared to the Series 2027, whereas a turnaround point exists in which the Series becomes more economical to operate, compared to both Parallel and the Reference aircraft after 2030. Finally, the Life Cycle Assessment suggests that the Series variants have a lower environmental impact compared to the respective Parallel variants and that both configurations have better scores than the Reference aircraft. The Parallel and Series configurations of 2030 promise an environmental impact reduction of up to 22.8 % and 59.8 % respectively, compared to the reference aircraft.
Assessment of (hybrid)-electric drive-train architectures for future aircraft applications
Authors: König P , Müller P , Höschler K
Published: June 2023

Future regional aircraft and propulsion systems will have to address both a growing market and stricter environmental constraints. Besides the increase of component efficiencies, the technological transformation from conventional to (hybrid)-electric propulsion systems represents a paradigm shift with great potential for the aviation industry. In this context, economic, market-relevant as well as technological boundary conditions for the electrical and mechanical components are developed in this paper for a reference regional aircraft and are based on current research results from different institutions. The propulsion performance analysis of a conventional turboprop is compared and evaluated with a serial-hybrid and a fully-electric configuration (both battery-electric), status today as well as status ~2035, as an example, whereby the presented process can also be applied to other hybrid configurations too. An energy-optimised propulsion and operating concept is derived with regard to minimum resulting system weight. The results of this analysis help to define necessary boundary conditions for future subsystem investigations and identify key research items, especially in the field of the battery.
Are batteries fit for hybrid-electric regional aircraft?
Authors: Kühnelt Helmut , Mastropierro Francesco , Zhang Ningxin , Toghyani Somayeh , Krewer Ulrike
Published: June 2023

Hybrid electric propulsion is likely to play a more prominent role for regional aircraft with 40+ passengers in the future air transport system with reduced climatic impact. In IMOTHEP, two hybrid-electric regional (HER) aircraft concepts, a conservative and a radical, are developed. Energy dense battery technologies are needed to enable hybrid-electric propulsion of regional aircraft. Furthermore, these batteries need to become commercially available within the planned development time of the new aircraft, i.e. until 2030. This paper will discuss general requirements for the HER battery and aims at providing an overview on the most promising industrial approaches for energy dense battery cell technologies – from advanced Li-ion to all-solid-state – with view of their application in air transport and forecasted availability on the market. Furthermore, results will be presented from the study performed in IMOTHEP on hybrid polymer-ceramic all-solid-state battery electrochemistry that combines lab trials with electrochemical numerical simulation.
Overall Aircraft Design: From the open-source FAST-OAD to its training branch
Authors: Sy Ousmane , Sy Birame , Lutz Florent , Sarr Abdoulaye , Bénard Emmanuel
Published: June 2023

Reducing the environmental footprint of commercial aviation to a manageable level, is a formidable challenge for the whole aeronautical community. In particular, new aircraft configurations could drastically reduce the environmental footprint. Training of engineers in Overall Aircraft Design (OAD) is, therefore, an essential step to be considered in order to take environmental issues into account from the preliminary design phase. ONERA and ISAE-SUPAERO have developed FAST-OAD (Future Aircraft Sizing Tool – Overall Aircraft Design), an open source platform for the analysis, sizing and optimization of aircraft, emphasizing on user-friendliness and modularity. The open source version provides a flexible and practical framework that allows researchers and industrial actors all around the world, to extend the entire aircraft design process to new challenging aircraft configurations, in-house models and higher fidelity approaches. In this contribution, the authors introduce, with a qualitative perspective, a training branch of FAST-OAD, to help trainers to build classes and tutorials.
Parametric model of aircraft external geometry as a component of FAST-OAD aircraft preliminary design system.
Authors: Grendysa Wojciech , Jézégou Joël , Benard Emmanuel
Published: June 2023

Rapid evolutions in fields such as aerospace propulsion, materials engineering, geometry modelling tools or optimization tools provide the opportunity to search for novel configurations of future aircraft in an expanding domain. In order to effectively explore the space of variables of constantly expanding size, one needs tools that give the ability to automate this process. Such a tool is the Future Aircraft Sizing Tool for Overall Aircraft Design or FAST-OAD. FAST-OAD allows for rapid estimation of aircraft size, based on set, so-called Top Level Aircraft Requirements (TLARs) by using multi-disciplinary and multi-fidelity analysis and optimization.

An essential component of such a system is a module capable of modelling the external geometry of the calculated case. This article describes an attempt to use a powerful commercial Computer Aided Design software, Siemens NX, to model the aircraft external geometry based on the results of the analysis performed by FAST-OAD. This approach, compared to previous works, brings some limitations but, on the other hand, gives the possibility to base the geometry on a mathematically consistent model and helps to better understand the set of parameters necessary to describe the geometry correctly.

The main objective of this research is to provide a tool that allows the automatic generation of aircraft exterior geometry based on the output parameters received from the FAST-OAD package.

An additional goal of this activity is to determine the parameter set necessary to properly define the external geometry, but at the same time not containing redundant, dependent geometric parameters. The minimum number of independent parameters necessary to completely describe the external geometry is sought.
Numerical Investigation of the Magnetic Alignment of Fe-Co-Coated Single Reinforcement Fibers
Authors: Xu Yun , Winkler Anja , Helwig Martin , Modler Niels , Gude Maik , Dittes Axel , Höhlich Dominik , Lampke Thomas
Published: June 2023

Fiber-reinforced composites are progressively more used in a variety of industrial applications. In recent years, carbon fiber-reinforced plastics have become increasingly popular, particularly in the aerospace sector because they offer outstanding mechanical properties combined with low weight. However, the orientation and distribution of the fibers have a significant effect on the mechanical and physical properties of the composite materials. Using conventional manufacturing technologies, it is not always technologically possible to adjust the fiber orientation to the load direction. One possible approach to targeted fiber alignment is the combination of classical manufacturing processes with a superimposed alignment mechanism so that the fibers can be oriented according to the load during component manufacturing. In this context, the orientation and distribution of short and long fibers through an external magnetic field seem to be well-suited to be integrated into the conventional manufacturing process of fiber-reinforced composites. Therefore, the generally non-magnetic reinforcement fibers, e.g. carbon or glass fibers, need to be modified or coated with magnetic materials. In this paper, carbon fibers coated with an iron-cobalt alloy are prepared by electrodeposition for the validation of simulation models developed in previous studies. Furthermore, numerical studies are presented in regard to the orientation of such fibers in polymeric matrices. Thus, simulative investigations of the orientability of coated carbon fibers in polymeric materials are shown and the works provide an important reference for future studies of fiber orientation and alignment using magnetic fields.
Coupling of a zonal air and temperature distribution model with an low pressure environmental control system ducting model
Authors: Matheis C , Korth P , Norrefeldt V , Lindner A , Urzua-Reichl K , Munoz-Sanchez M
Published: June 2023

The Regional Cabin Demonstrator is developed within the Clean Sky 2 project and integrates the latest developments in sustainable and high-performance cabin interiors for enhanced passenger experience. Within this project, an innovative low pressure environmental control system (ECS) ducting is developed and integrated into the demonstrator. Together with these hardware demonstration efforts, the associated model based development capabilities are strengthened. The goal is to virtually design the aircraft prior to its actual hardware integration. Such integration requires heterogeneous submodels interaction in an overall aircraft model. The current work presents such a model coupling. On the one hand, a component database for 1D system simulation is developed. By connecting these parameterized component models, it is possible to build any desired low pressure ECS system for which the pressure drop and the air outlet flow distributions are calculated. This system model is interfaced with a zonally decomposed indoor environment Modelica-model of the Regional Cabin Demonstrator showing resulting cabin air temperature, stratification and airflow. Both models interact on the one hand because the air temperature and distribution in the air outlets generates a boundary condition for the zonal model. On the other hand, part of the cabin exhaust air is recirculated and thus generates a boundary condition for the low pressure ECS model. The coupling is performed by the functional mock-up (FMU) standard allowing to couple different models through standardized in- and outputs while maintaining protection of individual partners’ IP. The model application is demonstrated on the example of a cruise condition thermal boundary condition.
In-Situ Computed Tomography — Analysis of a Single-Lap Shear Test with Composite-Metal Pin Joints
Authors: Köhler Daniel , Popp Julian , Kupfer Robert , Troschitz Juliane , Drummer Dietmar , Gude Maik
Published: June 2023

Lightweight design in the form of intelligent multi-material structures that combine the advantages of high strength steel and continuous fibre reinforced thermoplastics (CFRTs) gain increasing relevance. In this context, the joining operation is a major challenge as it has to be time and cost efficient and the resulting joint has to exhibit a high mechanical durability. One possible approach is the use of cold formed pin structures, which can be inserted into the CFRT to create a form fitting joint under avoidance of fibre damage as it is commonly the case for bolted or riveted joints. The deformation phenomena of pin joints are usually investigated by macrosectioning or (ex-situ) computed tomography. However, due to resetting elastic deformations and cracks that close after unloading an inaccurate state of the inner joint structure is measured. Furthermore, an investigation of different stages with increasing load and progressing failure is very time consuming, because multiple samples have to be tested and investigated. Alternatively, in-situ computed tomography (in-situ CT) can be used to investigate the testing of pin joints. In this paper, a method for in-situ CT analysis of a single-lap shear test with composite-metal pin joints is presented. The pins are plastically extruded to a height of approx. 1.8 mm from the metal sheet (1.5 mm thick) and are pressed into a locally heated glass fibre reinforced thermoplastic (FRT) sheet (approx. 2 mm thick) creating a form fit. Specimens with quasi-unidirectional fibre reinforcement in 0° and 90° direction are tested. With this procedure, the three-dimensional deformation of the joint can be observed and failure phenomena can be identified for each reinforcement direction respectively. Thus, this method can also be used for validating numerical simulations.
Integration of sensors in sandwich composites for the detection of structural damage
Authors: Lehmann F , Bätzel T , Steinbild P J , Winkler A , Modler N , Woog M , Matassini L , Sauer S
Published: June 2023

A decisive factor in achieving the climate targets of the German government is the reduction of CO2 through the gradual electrification of transport. In battery-electric vehicles, the energy storage system is typically positioned close to the ground under the passenger cell. Thus, the crossing of obstacles or typical load scenarios affecting the underbody play a crucial role for vehicle safety. Currently, such battery protection structures usually consist of thick-walled aluminum, steel or titanium constructions, which results in increased weight and manufacturing costs [1]. Higher moving masses in battery electric vehicles lead to high resource consumption in their life cycle. In this context, battery protection structures represent lightweight structures that are safety critical parts protecting the battery system from impact events and medial influences. Additionally, these parts are in general large-scale parts, which show a high potential for mass reduction and functional integration of a conditions monitoring system. Therefore, the focus of the presented paper is on the development of a functionally integrative lightweight battery protection structure, which consist of a sandwich lay-up of glass fiber reinforced plastic (GRP) cover sheets and polymeric foam in the middle. In addition to the purely mechanical protection of the energy storage unit, this structure should be able to detect and classify any damage occurring of the battery module above it caused by impact events. Thus, a structure-integrated sensor system is also focused, which shall be used for the determination of the extent of damage, which means that service activities or component replacements will only be carried out when necessary and not within predefined maintenance intervals. Based on a detailed requirement profile for the structure, a comparison of selected sensor concepts is carried out. For further investigations, three sensor types (pressure sensor, strain sensor, inductive sensors) are selected and examined in more detail. Thus, investigations in regard to the sensor positioning in the composite lay-up and the ability for detecting different load cases were planned and carried out. A further issue is the clarification of possible integration options in terms of manufacturing technology. For this purpose, the so-called e-preforming technology is used, which enables an automated application of functional elements. Therefore, different types of conductor track manufacturing and contacting of electronic components within the sandwich structure are investigated. The results of these initial investigations in the case of automotive applications show a high potential to be transferred to applications in the aviation or aeronautical industry. In particular, these also influence the approaches for the design and development of structural health monitoring components and systems.
A data-driven approach for health status assessment and remaining useful life prediction of aero-engine
Authors: De Giorgi M. G. , Menga N. , Mothakani A. , Ficarella A.
Published: June 2023

Artificial Intelligence (AI) algorithms are widely used to improve the health monitoring tools exploited in aeronautics and this result in an increase in reliability and flight safety. Furthermore, better management of maintenance costs is another positive consequence of the application of AI-based health monitoring tools. In this paper, two AI-based health monitoring tools are developed to predict the Remaining Useful Life (RUL) of a fleet of simple turbojet engines VIPER 632 – 43 subject to a compressor degradation process. The AI algorithms used in this work are the Nonlinear Autoregressive Network with Exogenous Inputs (NARX) and the Long Short-Term Memory (LSTM) neural networks, which are two types of Artificial Neural Network (ANN) particularly suitable for time-series forecasting. The data about engine operation in degraded condition necessary to develop the just cited tools are obtained by performing a series of simulations in transient condition in which a degraded state at the compressor is implemented. The Matlab&Simulink software, equipped with the T-MATS Simulink library developed by NASA is used to develop a virtual model of the VIPER 632 – 43 engine and to perform the simulation. Furthermore, an adequate mathematical model is used to simulate the trend of the degradation level during time.
Analysis of the fixing process of FBG optical sensors for thermomechanical monitoring of aerospace applications
Authors: Aimasso Alessandro , Dalla Vedova Matteo D.L. , Esposito Alfredo , Maggiore Paolo
Published: June 2023

In aerospace, lots of components can be defined as “safety critical”. As a result, it is crucial to early identify the failure precursors when the effects on the systems performances are still practically insignificant. For this reason, complex networks of sensors had been developed and integrated into different parts to monitor several operational parameters, useful for evaluating their health (such as such as temperatures, displacements, vibrations, etc). Clearly, due to the importance of data collected, the technology employed shall be very reliable, even while working in harsh environments. Sensors based on optical fiber Bragg grating (FBG) meet these requirements. However, the fiber’s integration process in the considered system is really crucial, from the moment that it could influence the sensors output. In this regard, gluing the optical sensors is really a critical activity, because the effects of the glue’s retire and its viscous assessment shall be analysed and quantified. In this work, it was done by comparing performances of two equal samples, each one with an FBG glued on it. The first sample was prepared about two months before the second one. Furthermore, data from both FBG have been collected from the gluing phase of the second sample and in the following days. The results showed that the assessment of the resin evolved in different phases, but all of them were united by the fact that the overall process makes sensors measures not reliable during this specific transitory phase. By observing the evolution of the linear fit gradients, it can be stated that the variations reached their maximum in the middle of the gluing process, when the fiber was detached from the tensioning device. Finally, at the end of the overall process, data output resulted stable, so making FBG employable for reliable thermal or strain measures.
High-speed Digital Image Correlation (DIC) for measuring deformation and vibration of fast rotating fan blades
Authors: Goessling Jan , Seume Joerg R.
Published: June 2023

Due to ecological requirements, the bypass-ratio of future civil turbofan engines will be increased. This leads to ultra-high bypass ratio (UHBR) engines, which bring in new challenges concerning the blade material, structural integration, and aeroelastic behaviour of the fan. The ambition of the project Composite fan Aerodynamic, Aeroelastic, and Aeroacoustic Validation Rig (CA3ViAR) is to design and test an open-test-case fan that experiences instability mechanisms, which are representative for UHBR fans of civil aircrafts. The optical measurement technique Digital Image Correlation (DIC) allows for the spatial measurement of deformations. The aim is to apply this technique to measure rotor blade deformation under loading and its vibration due to aeroelastic phenomena to get a better understanding of the structural and aeroelastic behaviour of the composite fan. However, the high rotational speeds, blade vibration frequencies, and expected amplitudes pose challenges for the measurement setup. In this work, a high-speed DIC system is prepared and tested to measure deformation and vibration of a fast rotating blade. Additionally, the requirements for the DIC setup are defined and presented. The expected blade tip speeds in the CA3ViAR project are up to 295 m/s and the blade frequencies of interest up to 650 Hz. Therefore, particular emphasis must be given to the setup in order to eliminate motion blur due to the rotation and to achieve the required frequency. This leads to a setup with synchronised high-speed cameras and a laser to measure frequency vibrations up to 1 kHz with an exposure time below 210 ns. Test measurements are conducted on a stationary beam and an axial blower with a max. blade tip speed of 50 m/s. A data analysis method is developed and described to eliminate the rigid body rotation, analyse the deformation of each blade compared to a reference condition, and analyse the spatial vibration in the frequency domain for a high number of data points per time step. The results of the structural beam are in agreement with the reference measurements and numerical simulations. By analysing the spatial vibration modes of the axial blower, the 1F-flap mode is identified at 38 Hz. In conclusion, this DIC setup shows promising results for future deformation and vibration measurements on a scaled UHBR fan.
Assessing Single Pilot Incapacitation using Low-Fidelity Simulation
Authors: Castro Ana Lidia de Almeida , Reis Ricardo Jose Nunes dos , Mallozzi Gianmaria , Vizioli Aurora De Bortoli
Published: June 2023

In the framework of the SAFELAND project, a Low-Fidelity Simulation (LFS) tool was developed and applied in collaboration with SAFEMODE project. This tool allows a preliminary evaluation of the system under development during its early stages, being an intermediate step between the concept development and other hands-on simulation activities, such as Real-Time Simulations (RTS). The LFS is simpler and less costly than RTS, but already involves final users in immersive human-in-the-loop activities to experience the system at a low level of maturity, identifying key issues in roles, procedures, and human-automation interaction of the operational concept under evaluation. Therefore, the LFS was carried out to provide a first understanding and assessment of different aspects of the feasibility of the core ideas regarding the SAFELAND concept of operations, which addresses incapacitation during landing of a Single Pilot operated aircraft with the support of a Ground Station. Despite the limitations of the console slide deck and the activity itself, the level of engagement was perceived as high by involved participants and the LFS was considered a valuable tool for a first assessment of the new operational concept. In this way, key points of the concept were uncovered and better understood both during development and execution of the LFS, for example: workload, situational awareness, and feasibility of roles, responsibilities, and new procedures. Broader issues were also explored, such as the dynamic between on-board pilot and ground station pilot, in addition to that of the pilots and Air Traffic Control (ATC).
Multisensor Avionics Architecture for BVLOS Drone Services
Authors: Giovagnola Jessica , Fernandez Miguel Molina , Beneder Roman , Schmitt Patrick , Cuellar Manuel Pegalajar , Santos Diego Pedro Morales
Published: June 2023

This ADACORSA demonstrator focuses on the implementation of a fail-operational avionics architecture combining Commercial Off-The-Shelf (COTS) elements from the automotive, the aerospace and the artificial intelligence world. A collaborative sensor setup (Time-of-Flight camera and FMCW RADAR from Infineon Technologies, stereo camera, LiDAR, IMU and GPS) allows to test heterogeneous sensor fusion solutions. A Tricore Architecture on AURIX™ Microcontroller supports the execution of safety supervision tasks as well as data fusion. A powerful embedded computer platform (NVIDIA Jetson Nano) accelerates AI algorithms performance and data processing. Furthermore, an FPGA enables power optimization of Artificial Neural Networks. Finally, a Pixhawk open-source flight controller ensures stabilization during normal flight operation and provides computer vision software modules allowing further processing of the captured, filtered and optimized environmental data. This paper shows various hardware and software implementations highlighting their emerging application within BVLOS drone services.
Path planning of autonomous UAVs using reinforcement learning
Authors: Chronis Christos , Anagnostopoulos Georgios , Politi Elena , Garyfallou Antonios , Varlamis Iraklis , Dimitrakopoulos George
Published: June 2023

Autonomous BVLOS Unmanned Aerial Vehicles (UAVs) are gradually gaining their share in the drone market. Together with the demand for extended levels of autonomy comes the necessity for high-performance obstacle avoidance and navigation algorithms that will allow autonomous drones to operate with minimum or no human intervention. Traditional AI algorithms have been extensively used in the literature for finding the shortest path in 2-D or 3-D environments and navigating the drones successfully through a known and stable environment. However, the situation can become much more complicated when the environment is changing or not known in advance. In this work, we explore the use of advanced artificial intelligence techniques, such as reinforcement learning, to successfully navigate a drone within unspecified environments. We compare our approach against traditional AI algoriths in a set of validation experiments on a simulation environment, and the results show that using only a couple of low-cost distance sensors it is possible to successfully navigate the drone beyond the obstacles.
An application of the SAFEMODE methodology to drone operations
Authors: Giulia Vicario Anna , Matteo Cocchioni , Simone Pozzi
Published: June 2023

This paper describes the application of a new methodological approach developed within the SAFEMODE project intending to improve the results of human factors analysis obtained from the existing investigation methods. This set of methodologies comprehends, on the one hand, models and techniques already used in the aviation domain, a benchmark for safety practices, and on the other hand, a new framework and taxonomy developed within the SAFEMODE projects. The combined use of these methodologies has been applied to analyse accidents and near misses in a company operating with drones to demonstrate its usability in the drone domain. The results confirmed the effectiveness of the methodologies in finding an increased number of unsafe acts, contextual preconditions and latent organisational factors involved in different accidents, near misses and occurrences, compared to a more “traditional” approach. The use of these techniques has already been recognised as very promising in the maritime domain where such a study had already been successfully conducted.
An empirical analysis of airport capacity evaluation: insights regarding air traffic design hours
Authors: Rodríguez-Sanz Álvaro , Andrada Luis Rubio
Published: June 2023

An important and challenging question for air transportation regulators and airport operators is the definition and specification of airport capacity. Airport capacity is rather difficult to describe due to its multi-faceted and dynamic nature, and it depends both on the available infrastructure, on external factors and on operating procedures. Moreover, annual capacity is used for long term planning purposes as a degree of available service volume, but it poses several inefficiencies when measuring the true throughput of the system because of seasonal and daily variations of traffic. Instead, airport throughput is calculated or estimated for a short period of time, usually one hour. This brings about a mismatch: air traffic forecasts typically yield annual volumes, whereas capacity is measured on hourly figures. To manage the right balance between airport capacity and demand, annual traffic volumes must be converted into design hour volumes so that they can be compared with the true throughput of the system. This comparison is a cornerstone in planning new airport infrastructures, as design-period parameters are important for airport planners in anticipating where and when congestion occurs. Although the design hour for airport traffic has historically had a number of definitions, it is necessary to improve the way air traffic design hours are selected. By reviewing the relationships between hourly and annual air traffic volumes at 50 European airports during the period 2004-2021, this paper discusses the problem of defining a suitable peak hour for capacity evaluation purposes. Additionally, we appraise different daily traffic distribution patterns and their variation by hour of the day. The clustering of airports with respect to their capacity, operational, and traffic characteristics allows us to discover functional relationships between design hours and annual volumes. These relationships help us to propose empirical methods to derive expected traffic in design hours from annual volumes. This could be used to properly assess airport expansion projects or to optimise resource allocation tasks. Finally, we provide new evidence on the nature of airport capacity and the dynamics of air traffic design hours.
Modelling and simulation of urban air mobility: an extendable approach
Authors: Naeem Nabih , Ratei Patrick , Prakasha Prajwal Shiva
Published: June 2023

This paper presents an extendable approach to the modelling and simulation of Urban Air Mobility (UAM), and dissemination criteria for system of systems simulation driven studies. UAM involves a multitude of complexities including the airspace, fleet, demand, and vertidrome management. Simulation is a key enabler for understanding these complexities and the interaction of the different stakeholders within the UAM paradigm. This work builds upon past research of the authors and presents a framework for simulation and modelling which includes the modelling of passenger demand, passenger mode choice, vehicle allocation for heterogenous fleets, route planning, deadheading, vertidrome scheduling, and flight scheduling with stop-overs. The approach presented in this work can be used to model both on-demand and scheduled operations, while the primary focus is placed on the former. Moreover, different methods can be implemented for the detailed modelling of the stakeholders, in addition to parametrically varying aspects such as the fleet size, number of vertidromes, and others. The aims of this paper are two, firstly to offer a framework for the modelling of UAM by breaking down its complexity systematically to simpler blocks, namely the stakeholders, the processes and interaction, through which the emergent behavior of the system of systems simulation may be more easily observed or understood. Secondly, it is to provide a clear method for dissemination of the modelling and simulation with the goal of establishing a common standard, demonstrated through the dissemination of the authors’ simulation to the reader.
Measurement of the C12A7:e- thermionic emission enhancement due to photon exposure
Authors: Toledo J. , Post A. , Plaza J. F.
Published: June 2023

In this work, a test set-up device is designed, developed and manufactured to perform a direct measurement of the current emission enhancement that the photon absorption can bring to the thermionic emission in a Photon-Enhanced Thermionic Emission Device (PETED) where the C12A7:e- electride is used as the semiconductor due to its low work function value of 2.4 eV. Even though the measured thermionic emission starts at low operational temperatures, obtaining for example a current density emission of 5 mA/cm2 at 500 °C, there is barely an increase of 1% in the current emission when the device is exposed to a source of photons. This effect is mainly due to the presence of a dielectric layer at the material surface, which acts as a barrier, reduces the current enhancement effect from photon excitation, and drives to a limited efficiency of 27 μA/cm2/W.