bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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.
Full-scale simulations of ‘In-Air Capturing’ return mode for winged reusable launch vehicles
Authors: Singh Sunayna , Sippel Martin , Stappert Sven 
Published: June 2023

Abstract
The recent success of reusable launchers has become a driving force for sustainable launch technologies. An innovative approach proposed by DLR, involves winged rocket stages captured mid air and towed back to the launch site by an aircraft. This recovery concept known as ‘In-Air Capturing (IAC)’, shows potential for substantial cost reduction, when compared to existing return modes. In the light of the Horizon 2020 project FALCon, full-scale simulations and sub-scale flight testing were carried out for further development of the technology. The paper summarizes the full-scale studies performed within FALCon. The full-scale test cases are introduced and the simulation framework for analysis of trajectories is presented. Then, the IAC maneuver is analyzed through trajectory simulations. Major external disturbances coming from the wake of the aircraft and flexibility of the rope connecting the rocket stage to the aircraft (after capture) are also addressed.