@article{StiemerThomaBraun2023, author = {Stiemer, Luc Nicolas and Thoma, Andreas and Braun, Carsten}, title = {MBT3D: Deep learning based multi-object tracker for bumblebee 3D flight path estimation}, series = {PLoS ONE}, volume = {18}, journal = {PLoS ONE}, number = {9}, publisher = {PLOS}, address = {San Fancisco}, issn = {1932-6203}, doi = {10.1371/journal.pone.0291415}, pages = {e0291415}, year = {2023}, abstract = {This work presents the Multi-Bees-Tracker (MBT3D) algorithm, a Python framework implementing a deep association tracker for Tracking-By-Detection, to address the challenging task of tracking flight paths of bumblebees in a social group. While tracking algorithms for bumblebees exist, they often come with intensive restrictions, such as the need for sufficient lighting, high contrast between the animal and background, absence of occlusion, significant user input, etc. Tracking flight paths of bumblebees in a social group is challenging. They suddenly adjust movements and change their appearance during different wing beat states while exhibiting significant similarities in their individual appearance. The MBT3D tracker, developed in this research, is an adaptation of an existing ant tracking algorithm for bumblebee tracking. It incorporates an offline trained appearance descriptor along with a Kalman Filter for appearance and motion matching. Different detector architectures for upstream detections (You Only Look Once (YOLOv5), Faster Region Proposal Convolutional Neural Network (Faster R-CNN), and RetinaNet) are investigated in a comparative study to optimize performance. The detection models were trained on a dataset containing 11359 labeled bumblebee images. YOLOv5 reaches an Average Precision of AP = 53, 8\%, Faster R-CNN achieves AP = 45, 3\% and RetinaNet AP = 38, 4\% on the bumblebee validation dataset, which consists of 1323 labeled bumblebee images. The tracker's appearance model is trained on 144 samples. The tracker (with Faster R-CNN detections) reaches a Multiple Object Tracking Accuracy MOTA = 93, 5\% and a Multiple Object Tracking Precision MOTP = 75, 6\% on a validation dataset containing 2000 images, competing with state-of-the-art computer vision methods. The framework allows reliable tracking of different bumblebees in the same video stream with rarely occurring identity switches (IDS). MBT3D has much lower IDS than other commonly used algorithms, with one of the lowest false positive rates, competing with state-of-the-art animal tracking algorithms. The developed framework reconstructs the 3-dimensional (3D) flight paths of the bumblebees by triangulation. It also handles and compares two alternative stereo camera pairs if desired.}, language = {en} } @inproceedings{FunkeBeckmannStefanetal.2023, author = {Funke, Harald and Beckmann, Nils and Stefan, Lukas and Keinz, Jan}, title = {Hydrogen combustor integration study for a medium range aircraft engine using the dry-low NOx "Micromix" combustion principle}, series = {Proceedings of the ASME Turbo Expo 2023: Turbomachinery Technical Conference and Exposition. Volume 1: Aircraft Engine. Boston, Massachusetts, USA. June 26-30, 2023}, booktitle = {Proceedings of the ASME Turbo Expo 2023: Turbomachinery Technical Conference and Exposition. Volume 1: Aircraft Engine. Boston, Massachusetts, USA. June 26-30, 2023}, publisher = {ASME}, address = {New York}, isbn = {978-0-7918-8693-9}, doi = {10.1115/GT2023-102370}, pages = {12 Seiten}, year = {2023}, abstract = {The feasibility study presents results of a hydrogen combustor integration for a Medium-Range aircraft engine using the Dry-Low-NOₓ Micromix combustion principle. Based on a simplified Airbus A320-type flight mission, a thermodynamic performance model of a kerosene and a hydrogen-powered V2530-A5 engine is used to derive the thermodynamic combustor boundary conditions. A new combustor design using the Dry-Low NOx Micromix principle is investigated by slice model CFD simulations of a single Micromix injector for design and off-design operation of the engine. Combustion characteristics show typical Micromix flame shapes and good combustion efficiencies for all flight mission operating points. Nitric oxide emissions are significant below ICAO CAEP/8 limits. For comparison of the Emission Index (EI) for NOₓ emissions between kerosene and hydrogen operation, an energy (kerosene) equivalent Emission Index is used. A full 15° sector model CFD simulation of the combustion chamber with multiple Micromix injectors including inflow homogenization and dilution and cooling air flows investigates the combustor integration effects, resulting NOₓ emission and radial temperature distributions at the combustor outlet. The results show that the integration of a Micromix hydrogen combustor in actual aircraft engines is feasible and offers, besides CO₂ free combustion, a significant reduction of NOₓ emissions compared to kerosene operation.}, language = {en} } @article{HammerQuitterMayntzetal.2023, author = {Hammer, Thorben and Quitter, Julius and Mayntz, Joscha and Bauschat, J.-Michael and Dahmann, Peter and G{\"o}tten, Falk and Hille, S. and Stumpf, E.}, title = {Free fall drag estimation of small-scale multirotor unmanned aircraft systems using computational fluid dynamics and wind tunnel experiments}, series = {CEAS Aeronautical Journal}, journal = {CEAS Aeronautical Journal}, publisher = {Springer}, address = {Wien}, issn = {1869-5590 (Online)}, doi = {10.1007/s13272-023-00702-w}, pages = {14 Seiten}, year = {2023}, abstract = {New European Union (EU) regulations for UAS operations require an operational risk analysis, which includes an estimation of the potential danger of the UAS crashing. A key parameter for the potential ground risk is the kinetic impact energy of the UAS. The kinetic energy depends on the impact velocity of the UAS and, therefore, on the aerodynamic drag and the weight during free fall. Hence, estimating the impact energy of a UAS requires an accurate drag estimation of the UAS in that state. The paper at hand presents the aerodynamic drag estimation of small-scale multirotor UAS. Multirotor UAS of various sizes and configurations were analysed with a fully unsteady Reynolds-averaged Navier-Stokes approach. These simulations included different velocities and various fuselage pitch angles of the UAS. The results were compared against force measurements performed in a subsonic wind tunnel and provided good consistency. Furthermore, the influence of the UAS`s fuselage pitch angle as well as the influence of fixed and free spinning propellers on the aerodynamic drag was analysed. Free spinning propellers may increase the drag by up to 110\%, depending on the fuselage pitch angle. Increasing the fuselage pitch angle of the UAS lowers the drag by 40\% up to 85\%, depending on the UAS. The data presented in this paper allow for increased accuracy of ground risk assessments.}, language = {en} } @article{ThomessenThomaBraun2023, author = {Thomessen, Karolin and Thoma, Andreas and Braun, Carsten}, title = {Bio-inspired altitude changing extension to the 3DVFH* local obstacle avoidance algorithm}, series = {CEAS Aeronautical Journal}, journal = {CEAS Aeronautical Journal}, publisher = {Springer}, address = {Wien}, issn = {1869-5590 (Online)}, doi = {10.1007/s13272-023-00691-w}, pages = {11 Seiten}, year = {2023}, abstract = {Obstacle avoidance is critical for unmanned aerial vehicles (UAVs) operating autonomously. Obstacle avoidance algorithms either rely on global environment data or local sensor data. Local path planners react to unforeseen objects and plan purely on local sensor information. Similarly, animals need to find feasible paths based on local information about their surroundings. Therefore, their behavior is a valuable source of inspiration for path planning. Bumblebees tend to fly vertically over far-away obstacles and horizontally around close ones, implying two zones for different flight strategies depending on the distance to obstacles. This work enhances the local path planner 3DVFH* with this bio-inspired strategy. The algorithm alters the goal-driven function of the 3DVFH* to climb-preferring if obstacles are far away. Prior experiments with bumblebees led to two definitions of flight zone limits depending on the distance to obstacles, leading to two algorithm variants. Both variants reduce the probability of not reaching the goal of a 3DVFH* implementation in Matlab/Simulink. The best variant, 3DVFH*b-b, reduces this probability from 70.7 to 18.6\% in city-like worlds using a strong vertical evasion strategy. Energy consumption is higher, and flight paths are longer compared to the algorithm version with pronounced horizontal evasion tendency. A parameter study analyzes the effect of different weighting factors in the cost function. The best parameter combination shows a failure probability of 6.9\% in city-like worlds and reduces energy consumption by 28\%. Our findings demonstrate the potential of bio-inspired approaches for improving the performance of local path planning algorithms for UAV.}, language = {en} } @article{BaaderBoxbergChenetal.2023, author = {Baader, Fabian and Boxberg, Marc S. and Chen, Qian and F{\"o}rstner, Roger and Kowalski, Julia and Dachwald, Bernd}, title = {Field-test performance of an ice-melting probe in a terrestrial analogue environment}, series = {Icarus}, journal = {Icarus}, number = {409}, publisher = {Elsevier}, address = {Amsterdam}, doi = {10.1016/j.icarus.2023.115852}, pages = {Artikel 115852}, year = {2023}, abstract = {Melting probes are a proven tool for the exploration of thick ice layers and clean sampling of subglacial water on Earth. Their compact size and ease of operation also make them a key technology for the future exploration of icy moons in our Solar System, most prominently Europa and Enceladus. For both mission planning and hardware engineering, metrics such as efficiency and expected performance in terms of achievable speed, power requirements, and necessary heating power have to be known. Theoretical studies aim at describing thermal losses on the one hand, while laboratory experiments and field tests allow an empirical investigation of the true performance on the other hand. To investigate the practical value of a performance model for the operational performance in extraterrestrial environments, we first contrast measured data from terrestrial field tests on temperate and polythermal glaciers with results from basic heat loss models and a melt trajectory model. For this purpose, we propose conventions for the determination of two different efficiencies that can be applied to both measured data and models. One definition of efficiency is related to the melting head only, while the other definition considers the melting probe as a whole. We also present methods to combine several sources of heat loss for probes with a circular cross-section, and to translate the geometry of probes with a non-circular cross-section to analyse them in the same way. The models were selected in a way that minimizes the need to make assumptions about unknown parameters of the probe or the ice environment. The results indicate that currently used models do not yet reliably reproduce the performance of a probe under realistic conditions. Melting velocities and efficiencies are constantly overestimated by 15 to 50 \% in the models, but qualitatively agree with the field test data. Hence, losses are observed, that are not yet covered and quantified by the available loss models. We find that the deviation increases with decreasing ice temperature. We suspect that this mismatch is mainly due to the too restrictive idealization of the probe model and the fact that the probe was not operated in an efficiency-optimized manner during the field tests. With respect to space mission engineering, we find that performance and efficiency models must be used with caution in unknown ice environments, as various ice parameters have a significant effect on the melting process. Some of these are difficult to estimate from afar.}, language = {en} } @incollection{HeimesKampkerDornetal.2023, author = {Heimes, Heiner Hans and Kampker, Achim and Dorn, Benjamin and Kehrer, Mario and D{\"u}nnwald, Simon and Badura, Dennis and Terren, Maximilian and R{\"o}th, Thilo}, title = {Produktionsprozesse der Fahrzeugstruktur}, series = {Elektromobilit{\"a}t: Grundlagen einer Fortschrittstechnologie}, booktitle = {Elektromobilit{\"a}t: Grundlagen einer Fortschrittstechnologie}, editor = {Kampker, Achim and Heimes, Heiner Hans}, publisher = {Springer Vieweg}, address = {Berlin}, isbn = {978-3-662-65811-6 (Print)}, doi = {10.1007/978-3-662-65812-3_13}, pages = {227 -- 247}, year = {2023}, language = {de} } @incollection{HeimesKampkerKehreretal.2023, author = {Heimes, Heiner Hans and Kampker, Achim and Kehrer, Mario and D{\"u}nnwald, Simon and Heetfeld, Lennart and Polzenberg, Jens and Budde, Lucas and Keusen, Maximilian and Pandey, Rahul and R{\"o}th, Thilo}, title = {Fahrzeugstruktur}, series = {Elektromobilit{\"a}t: Grundlagen einer Fortschrittstechnologie}, booktitle = {Elektromobilit{\"a}t: Grundlagen einer Fortschrittstechnologie}, editor = {Kampker, Achim and Heimes, Heiner Hans}, publisher = {Springer Vieweg}, address = {Berlin}, isbn = {978-3-662-65811-6 (Print)}, doi = {10.1007/978-3-662-65812-3_5}, pages = {69 -- 106}, year = {2023}, abstract = {Um sowohl Treibhausgas-Emissionen zu verringern als auch Kraftstoffressourcen zu schonen, wird zunehmend an einer Transformation konventionell angetriebener Kraftfahrzeuge hin zu elektrifizierten Antriebskonzepten gearbeitet. Basierend auf herk{\"o}mmlichen Fahrzeugen mit Verbrennungsmotor wurde eine Vielzahl neuer Antriebssysteme mit verschiedenem Elektrifizierungsgrad entwickelt. Mitte der 1990er-Jahre kamen erste Fahrzeuge mit einem Hybridantrieb auf den Markt. Die Kombination aus Verbrennungs- und Elektromotor erlaubt eine Verbrauchsreduktion und Bremsenergier{\"u}ckgewinnung sowie lokal emissionsfreies Fahren.}, language = {de} } @book{JanserHavermannHoeveleretal.2023, author = {Janser, Frank and Havermann, Marc and Hoeveler, Bastian and Hertz, Cyril and Bergmann, Ole}, title = {Str{\"o}mungslehre und Aerodynamik : inkompressible Profile und Tragfl{\"u}gelaerodynamik, Band 2}, edition = {4. Auflage}, publisher = {Mainz}, address = {Aachen}, isbn = {978-3-8107-0261-6}, pages = {XIII, 211 Seiten}, year = {2023}, abstract = {Das vorliegende Buch dient als Grundlage f{\"u}r die Bachelor- und Master-Ausbildung von Studierenden im Fachgebiet Str{\"o}mungslehre und Aerodynamik. Im hier behandelten Teilbereich der inkompressiblen Profile und Tragfl{\"u}gelaerodynamik werden schwerpunktm{\"a}ßig die folgenden Themen besprochen: - Profilaerodynamik - Tragfl{\"u}gelaerodynamik - Flugzeugpolare - Methoden zur Flugbereichserweiterung - Schwebeschub und Schwebeleistung - Propellerblattaerodynamik - Numerische Methoden zur Tragfl{\"u}gelberechnung}, language = {de} } @article{ThomaThomessenGardietal.2023, author = {Thoma, Andreas and Thomessen, Karolin and Gardi, Alessandro and Fisher, A. and Braun, Carsten}, title = {Prioritising paths: An improved cost function for local path planning for UAV in medical applications}, series = {The Aeronautical Journal}, journal = {The Aeronautical Journal}, number = {First View}, publisher = {Cambridge University Press}, address = {Cambridge}, issn = {0001-9240 (Print)}, doi = {10.1017/aer.2023.68}, pages = {1 -- 18}, year = {2023}, abstract = {Even the shortest flight through unknown, cluttered environments requires reliable local path planning algorithms to avoid unforeseen obstacles. The algorithm must evaluate alternative flight paths and identify the best path if an obstacle blocks its way. Commonly, weighted sums are used here. This work shows that weighted Chebyshev distances and factorial achievement scalarising functions are suitable alternatives to weighted sums if combined with the 3DVFH* local path planning algorithm. Both methods considerably reduce the failure probability of simulated flights in various environments. The standard 3DVFH* uses a weighted sum and has a failure probability of 50\% in the test environments. A factorial achievement scalarising function, which minimises the worst combination of two out of four objective functions, reaches a failure probability of 26\%; A weighted Chebyshev distance, which optimises the worst objective, has a failure probability of 30\%. These results show promise for further enhancements and to support broader applicability.}, language = {en} } @incollection{DachwaldUlamecKowalskietal.2023, author = {Dachwald, Bernd and Ulamec, Stephan and Kowalski, Julia and Boxberg, Marc S. and Baader, Fabian and Biele, Jens and K{\"o}mle, Norbert}, title = {Ice melting probes}, series = {Handbook of Space Resources}, booktitle = {Handbook of Space Resources}, editor = {Badescu, Viorel and Zacny, Kris and Bar-Cohen, Yoseph}, publisher = {Springer}, address = {Cham}, isbn = {978-3-030-97912-6 (Print)}, doi = {10.1007/978-3-030-97913-3_29}, pages = {955 -- 996}, year = {2023}, abstract = {The exploration of icy environments in the solar system, such as the poles of Mars and the icy moons (a.k.a. ocean worlds), is a key aspect for understanding their astrobiological potential as well as for extraterrestrial resource inspection. On these worlds, ice melting probes are considered to be well suited for the robotic clean execution of such missions. In this chapter, we describe ice melting probes and their applications, the physics of ice melting and how the melting behavior can be modeled and simulated numerically, the challenges for ice melting, and the required key technologies to deal with those challenges. We also give an overview of existing ice melting probes and report some results and lessons learned from laboratory and field tests.}, language = {en} }