@article{Wittmann2000, author = {Wittmann, Klaus}, title = {Overview of Space Operations at DLR}, year = {2000}, language = {en} } @article{DachwaldCarnelliVasile2007, author = {Dachwald, Bernd and Carnelli, I. and Vasile, M.}, title = {Optimizing low-thrust gravity assist interplanetary trajectories using evolutionary neurocontrollers / I. Carnelli ; B. Dachwald ; M. Vasile}, series = {IEEE Congress on Evolutionary Computation, 2007 : CEC 2007 ; 25 - 28 September 2007, Singapore}, journal = {IEEE Congress on Evolutionary Computation, 2007 : CEC 2007 ; 25 - 28 September 2007, Singapore}, publisher = {IEEE Service Center}, address = {Piscataway, NJ}, isbn = {978-1-424-41339-3}, pages = {965 -- 972}, year = {2007}, language = {en} } @article{Esch1991, author = {Esch, Thomas}, title = {Optimized design of the lubrication system of modern combustion engines. Verbesserte Ausf{\"u}hrung von Schmierungssystemen bei modernen Verbrennungsmotoren}, isbn = {0148-7191}, doi = {10.4271/912407}, pages = {1 -- 11}, year = {1991}, language = {en} } @article{Dachwald2005, author = {Dachwald, Bernd}, title = {Optimization of very-low-thrust trajectories using evolutionary neurocontrol}, series = {Acta Astronautica}, volume = {57}, journal = {Acta Astronautica}, number = {2-8}, publisher = {Elsevier}, address = {Amsterdam [u.a.]}, isbn = {1879-2030}, pages = {175 -- 185}, year = {2005}, abstract = {Searching optimal interplanetary trajectories for low-thrust spacecraft is usually a difficult and time-consuming task that involves much experience and expert knowledge in astrodynamics and optimal control theory. This is because the convergence behavior of traditional local optimizers, which are based on numerical optimal control methods, depends on an adequate initial guess, which is often hard to find, especially for very-low-thrust trajectories that necessitate many revolutions around the sun. The obtained solutions are typically close to the initial guess that is rarely close to the (unknown) global optimum. Within this paper, trajectory optimization problems are attacked from the perspective of artificial intelligence and machine learning. Inspired by natural archetypes, a smart global method for low-thrust trajectory optimization is proposed that fuses artificial neural networks and evolutionary algorithms into so-called evolutionary neurocontrollers. This novel method runs without an initial guess and does not require the attendance of an expert in astrodynamics and optimal control theory. This paper details how evolutionary neurocontrol works and how it could be implemented. The performance of the method is assessed for three different interplanetary missions with a thrust to mass ratio <0.15mN/kg (solar sail and nuclear electric).}, language = {en} } @article{Dachwald2005, author = {Dachwald, Bernd}, title = {Optimization of very-low-thrust trajectories using evolutionary neurocontrol}, series = {Acta Astronautica. 57 (2005), H. 2-8}, journal = {Acta Astronautica. 57 (2005), H. 2-8}, isbn = {0094-5765}, pages = {175 -- 185}, year = {2005}, language = {en} } @article{DachwaldOhndorfGill2009, author = {Dachwald, Bernd and Ohndorf, A. and Gill, E.}, title = {Optimization of low-thrust Earth-Moon transfers using evolutionary neurocontrol / Ohndorf, A. ; Dachwald, B. ; Gill, E.}, series = {IEEE Congress on Evolutionary Computation, 2009. CEC '09.}, journal = {IEEE Congress on Evolutionary Computation, 2009. CEC '09.}, isbn = {978-1-4244-2958-5}, pages = {358 -- 364}, year = {2009}, language = {en} } @article{Dachwald2004, author = {Dachwald, Bernd}, title = {Optimization of Interplanetary Solar Sailcraft Trajectories Using Evolutionary Neurocontrol}, series = {Journal of guidance, control, and dynamics. 27 (2004), H. 1}, journal = {Journal of guidance, control, and dynamics. 27 (2004), H. 1}, isbn = {0162-3192}, pages = {66 -- 72}, year = {2004}, language = {en} } @article{DachwaldSeboldt2002, author = {Dachwald, Bernd and Seboldt, Wolfgang}, title = {Optimization of Interplanetary Rendezvous Trajectories for Solar Sailcraft Using a Neurocontroller}, series = {A collection of technical papers / AIAA Astrodynamics Specialist Conference : Monterey, California, 5 - 8 August 2002. - Vol. 2}, journal = {A collection of technical papers / AIAA Astrodynamics Specialist Conference : Monterey, California, 5 - 8 August 2002. - Vol. 2}, publisher = {American Institute of Aeronautics and Astronautics}, address = {Reston, Va.}, isbn = {1-56347-549-9}, pages = {1263 -- 1270}, year = {2002}, language = {en} } @article{DachwaldOhndorfSeboldt2005, author = {Dachwald, Bernd and Ohndorf, A. and Seboldt, Wolfgang}, title = {Optimierung der Lageregelung von Raumfahrzeugen mit Niedrigschubantrieb mittels evolution{\"a}rer neuronaler Regler / A. Ohndorf ; B. Dachwald ; W. Seboldt}, series = {Deutscher Luft- und Raumfahrtkongress 2005 : Friedrichshafen, 26. bis 29. September 2005, Motto: Luft- und Raumfahrt - Grenzen {\"u}berwinden, Horizonte erweitern / Deutsche Gesellschaft f{\"u}r Luft- und Raumfahrt - Lilienthal-Oberth e.V. (DGLR). [Red.: Peter Brandt (verantwortlich)]. Bd. 3. - (Jahrbuch ... der Deutschen Gesellschaft f{\"u}r Luft- und Raumfahrt}, journal = {Deutscher Luft- und Raumfahrtkongress 2005 : Friedrichshafen, 26. bis 29. September 2005, Motto: Luft- und Raumfahrt - Grenzen {\"u}berwinden, Horizonte erweitern / Deutsche Gesellschaft f{\"u}r Luft- und Raumfahrt - Lilienthal-Oberth e.V. (DGLR). [Red.: Peter Brandt (verantwortlich)]. Bd. 3. - (Jahrbuch ... der Deutschen Gesellschaft f{\"u}r Luft- und Raumfahrt}, publisher = {DGLR}, address = {Bonn}, pages = {1971 -- 1978}, year = {2005}, language = {de} } @article{Dachwald2005, author = {Dachwald, Bernd}, title = {Optimal Solar Sail Trajectories for Missions to the Outer Solar System}, series = {Journal of guidance, control, and dynamics. 28 (2005), H. 6}, journal = {Journal of guidance, control, and dynamics. 28 (2005), H. 6}, isbn = {0162-3192}, pages = {1187 -- 1193}, year = {2005}, language = {en} } @article{Dachwald2004, author = {Dachwald, Bernd}, title = {Optimal Solar Sail Trajectories for Missions to the Outer Solar System}, series = {22nd AIAA Applied Aerodynamics Conference and Exhibit - AIAA/AAS Astrodynamics Specialist Conference and Exhibit - AIAA Guidance, Navigation, and Control Conference and Exhibit - AIAA Modeling and Simulation Technologies Conference and Exhibit - AIAA Atmospheric Flight Mechanics Conference and Exhibit : 16 - 19 August 2004, Providence, Rhode Island / American Institute of Aeronautics and Astronautics. - (AIAA meeting papers on disc ; 2004,14-15)}, journal = {22nd AIAA Applied Aerodynamics Conference and Exhibit - AIAA/AAS Astrodynamics Specialist Conference and Exhibit - AIAA Guidance, Navigation, and Control Conference and Exhibit - AIAA Modeling and Simulation Technologies Conference and Exhibit - AIAA Atmospheric Flight Mechanics Conference and Exhibit : 16 - 19 August 2004, Providence, Rhode Island / American Institute of Aeronautics and Astronautics. - (AIAA meeting papers on disc ; 2004,14-15)}, publisher = {American Inst. of Aeronautics and Astronautics}, address = {Reston, Va.}, pages = {2 CD-ROMs}, year = {2004}, language = {en} } @article{NeuJanserKhatibietal.2016, author = {Neu, Eugen and Janser, Frank and Khatibi, Akbar A. and Braun, Carsten and Orifici, Adrian C.}, title = {Operational Modal Analysis of a wing excited by transonic flow}, series = {Aerospace Science and Technology}, volume = {49}, journal = {Aerospace Science and Technology}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1270-9638}, doi = {10.1016/j.ast.2015.11.032}, pages = {73 -- 79}, year = {2016}, abstract = {Operational Modal Analysis (OMA) is a promising candidate for flutter testing and Structural Health Monitoring (SHM) of aircraft wings that are passively excited by wind loads. However, no studies have been published where OMA is tested in transonic flows, which is the dominant condition for large civil aircraft and is characterized by complex and unique aerodynamic phenomena. We use data from the HIRENASD large-scale wind tunnel experiment to automatically extract modal parameters from an ambiently excited wing operated in the transonic regime using two OMA methods: Stochastic Subspace Identification (SSI) and Frequency Domain Decomposition (FDD). The system response is evaluated based on accelerometer measurements. The excitation is investigated from surface pressure measurements. The forcing function is shown to be non-white, non-stationary and contaminated by narrow-banded transonic disturbances. All these properties violate fundamental OMA assumptions about the forcing function. Despite this, all physical modes in the investigated frequency range were successfully identified, and in addition transonic pressure waves were identified as physical modes as well. The SSI method showed superior identification capabilities for the investigated case. The investigation shows that complex transonic flows can interfere with OMA. This can make existing approaches for modal tracking unsuitable for their application to aircraft wings operated in the transonic flight regime. Approaches to separate the true physical modes from the transonic disturbances are discussed.}, language = {en} } @article{HavermannSeilerBolleretal.2005, author = {Havermann, Marc and Seiler, F. and Boller, F. and Mangold, P.}, title = {Operation of the ISL transonic shock tube in a high subsonic flow regime / Seiler, F. ; Havermann, M. ; Boller, F. ; Mangold, P. ; Takayama K.}, series = {Shock Waves : Proceedings of the 24th International Symposium on Shock Waves Beijing, China July 11-16, 2004 / edited by Z. Jiang}, journal = {Shock Waves : Proceedings of the 24th International Symposium on Shock Waves Beijing, China July 11-16, 2004 / edited by Z. Jiang}, publisher = {Springer}, address = {Berlin}, isbn = {978-3-540-22497-6}, pages = {307 -- 312}, year = {2005}, language = {en} } @article{BlomeChuHoelletal.1988, author = {Blome, Hans-Joachim and Chu, Y. and Hoell, J and Priester, W.}, title = {On the observational discrimination of Friedmann-Lema{\^i}tre models}, series = {Large Scale Structures of the Universe: Proceedings of the 130th Symposium of the International Astronomical Union, dedicated to the memory of Marc A. Aaronson (1950-1987) held in Balatonfured, Hungary, June 15-20, 1987. Edited by Jean Audouze, Marie-Christine Pelletan and Sandor Szalay.}, journal = {Large Scale Structures of the Universe: Proceedings of the 130th Symposium of the International Astronomical Union, dedicated to the memory of Marc A. Aaronson (1950-1987) held in Balatonfured, Hungary, June 15-20, 1987. Edited by Jean Audouze, Marie-Christine Pelletan and Sandor Szalay.}, publisher = {Kluwer Academic Publishers}, address = {Dordrecht}, isbn = {90-277-2742-2}, pages = {517}, year = {1988}, language = {en} } @article{BergmannMoehrenBraunetal.2023, author = {Bergmann, Ole and M{\"o}hren, Felix and Braun, Carsten and Janser, Frank}, title = {On the influence of elasticity on swept propeller noise}, series = {AIAA SCITECH 2023 Forum}, journal = {AIAA SCITECH 2023 Forum}, publisher = {AIAA}, address = {Reston, Va.}, doi = {10.2514/6.2023-0210}, year = {2023}, abstract = {High aerodynamic efficiency requires propellers with high aspect ratios, while propeller sweep potentially reduces noise. Propeller sweep and high aspect ratios increase elasticity and coupling of structural mechanics and aerodynamics, affecting the propeller performance and noise. Therefore, this paper analyzes the influence of elasticity on forward-swept, backward-swept, and unswept propellers in hover conditions. A reduced-order blade element momentum approach is coupled with a one-dimensional Timoshenko beam theory and Farassat's formulation 1A. The results of the aeroelastic simulation are used as input for the aeroacoustic calculation. The analysis shows that elasticity influences noise radiation because thickness and loading noise respond differently to deformations. In the case of the backward-swept propeller, the location of the maximum sound pressure level shifts forward by 0.5 °, while in the case of the forward-swept propeller, it shifts backward by 0.5 °. Therefore, aeroacoustic optimization requires the consideration of propeller deformation.}, language = {en} } @article{GoettenFingerHavermannetal.2018, author = {G{\"o}tten, Falk and Finger, Felix and Havermann, Marc and Braun, Carsten and Gomez, Francisco and Bill, C.}, title = {On the flight performance impact of landing gear drag reduction methods for unmanned air vehicles}, series = {Deutscher Luft- und Raumfahrtkongress 2018}, journal = {Deutscher Luft- und Raumfahrtkongress 2018}, publisher = {DGLR}, address = {Bonn}, doi = {10.25967/480058}, pages = {11 S.}, year = {2018}, abstract = {The flight performance impact of three different landing gear configurations on a small, fixed-wing UAV is analyzed with a combination of RANS CFD calculations and an incremental flight performance algorithm. A standard fixed landing gear configuration is taken as a baseline, while the influence of retracting the landing gear or applying streamlined fairings is investigated. A retraction leads to a significant parasite drag reduction, while also fairings promise large savings. The increase in lift-to-drag ratio is reduced at high lift coefficients due to the influence of induced drag. All configurations are tested on three different design missions with an incremental flight performance algorithm. A trade-off study is performed using the retracted or faired landing gear's weight increase as a variable. The analysis reveals only small mission performance gains as the aerodynamic improvements are negated by weight penalties. A new workflow for decision-making is presented that allows to estimate if a change in landing gear configuration is beneficial for a small UAV.}, language = {en} } @article{Dahmann1995, author = {Dahmann, Peter}, title = {Offen f{\"u}r neue Modelle. GL-Hydraulik setzt neues Simulationssystem ein}, series = {Fluid Heft Sonderpublikation Fluid-Technik. 29 (1995)}, journal = {Fluid Heft Sonderpublikation Fluid-Technik. 29 (1995)}, isbn = {0015-461X}, pages = {8 -- 10}, year = {1995}, language = {de} } @article{BlomeWilson1996, author = {Blome, Hans-Joachim and Wilson, Thomas L.}, title = {Observational cosmology from the moon. Wilson, Thomas, L.; Blome, Hans-Joachim}, series = {Engineering, construction, and operations in space V : proceedings of the Fifth International Conference on Space '96, Albuquerque, New Mexico, June 1-6, 1996 / sponsored by Aerospace Division of the American Society of Civil Engineers ... [et al.]; edite}, journal = {Engineering, construction, and operations in space V : proceedings of the Fifth International Conference on Space '96, Albuquerque, New Mexico, June 1-6, 1996 / sponsored by Aerospace Division of the American Society of Civil Engineers ... [et al.]; edite}, publisher = {The Society}, address = {New York}, isbn = {0-7844-0177-2}, pages = {864 -- 870}, year = {1996}, language = {en} } @article{RoethNowackBaumeister2006, author = {R{\"o}th, Thilo and Nowack, N. and Baumeister, E.}, title = {Numerische L{\"o}sungsans{\"a}tze zur Auslegung von Stahl-Leichtmetall-Hybriden aus Verbundguss f{\"u}r zuk{\"u}nftige Fahrzeugstrukturen / Nowack, N. ; R{\"o}th, T. ; Baumeister, E.}, series = {Berechnung und Simulation im Fahrzeugbau. Bd. 1 : Tagung W{\"u}rzburg, 27. und 28. September 2006 = Numerical analysis and simulation in vehicle engineering / VDI-Gesellschaft Fahrzeug- und Verkehrstechnik}, journal = {Berechnung und Simulation im Fahrzeugbau. Bd. 1 : Tagung W{\"u}rzburg, 27. und 28. September 2006 = Numerical analysis and simulation in vehicle engineering / VDI-Gesellschaft Fahrzeug- und Verkehrstechnik}, publisher = {VDI-Verl.}, address = {D{\"u}sseldorf}, isbn = {3-18-091967-1}, pages = {363 -- 368}, year = {2006}, language = {de} } @article{BohnFunkeGier1999, author = {Bohn, D. and Funke, Harald and Gier, J.}, title = {Numerical and Experimental Investigations on the Flow in a 4-Stage Turbine with Special Focus on the Development of a Radial Temperature Streak}, series = {ASME Turbo Expo 1999, Indianapolis, USA, 1999}, journal = {ASME Turbo Expo 1999, Indianapolis, USA, 1999}, year = {1999}, language = {en} }