@article{GazdaMaurischat2020, author = {Gazda, Quentin and Maurischat, Andreas}, title = {Special functions and Gauss-Thakur sums in higher rank and dimension}, publisher = {De Gruyter}, address = {Berlin}, pages = {26 Seiten}, year = {2020}, language = {en} } @incollection{Blome2013, author = {Blome, Hans-Joachim}, title = {Die Tragweite der physikalischen Kosmologie}, series = {Exploring Uncertainty}, booktitle = {Exploring Uncertainty}, publisher = {Springer Gabler}, address = {Wiesbaden}, isbn = {978-3-658-00897-0}, doi = {10.1007/978-3-658-00897-0_6}, pages = {105 -- 150}, year = {2013}, language = {de} } @inproceedings{AdamsLosekammCzupalla2020, author = {Adams, Moritz and Losekamm, Martin J. and Czupalla, Markus}, title = {Development of the Thermal Control System for the RadMap Telescope Experiment on the International Space Station}, series = {International Conference on Environmental Systems}, booktitle = {International Conference on Environmental Systems}, pages = {1 -- 10}, year = {2020}, language = {en} } @inproceedings{ThomaFisherBertrandetal.2020, author = {Thoma, Andreas and Fisher, Alex and Bertrand, Olivier and Braun, Carsten}, title = {Evaluation of possible flight strategies for close object evasion from bumblebee experiments}, series = {Living Machines 2020: Biomimetic and Biohybrid Systems}, booktitle = {Living Machines 2020: Biomimetic and Biohybrid Systems}, editor = {Vouloutsi, Vasiliki and Mura, Anna and Tauber, Falk and Speck, Thomas and Prescott, Tony J. and Verschure, Paul F. M. J.}, publisher = {Springer}, address = {Cham}, isbn = {978-3-030-64312-6}, doi = {10.1007/978-3-030-64313-3_34}, pages = {354 -- 365}, year = {2020}, language = {en} } @article{Schueckhaus2020, author = {Sch{\"u}ckhaus, Ulrich}, title = {Die SkyCab-Erfinder im WFMG-Interview}, series = {Business in MG}, journal = {Business in MG}, number = {1}, pages = {6 -- 7}, year = {2020}, language = {de} } @techreport{BlandfordDachwaldDigeletal.2015, author = {Blandford, Daniel and Dachwald, Bernd and Digel, Ilya and Espe, Clemens and Feldmann, Marco and Francke, Gero and Hiecke, Hannah and Kowalski, Julia and Lindner, Peter and Plescher, Engelbert and Sch{\"o}ngarth, Sarah}, title = {Enceladus Explorer : Schlussbericht — Version: 1.0}, publisher = {FH Aachen}, address = {Aachen}, doi = {10.2314/GBV:86319950X}, year = {2015}, language = {de} } @inproceedings{ThomaFisherBraun2020, author = {Thoma, Andreas and Fisher, Alex and Braun, Carsten}, title = {Improving the px4 avoid algorithm by bio-inspired flight strategies}, series = {DLRK2020 - „Luft- und Raumfahrt - Verantwortung in allen Dimensionen"}, booktitle = {DLRK2020 - „Luft- und Raumfahrt - Verantwortung in allen Dimensionen"}, doi = {10.25967/530183}, pages = {10 Seiten}, year = {2020}, language = {en} } @inproceedings{WuKemper2016, author = {Wu, Ziyi and Kemper, Hans}, title = {The optimal 48 V - battery pack for a specific load profile of a heavy duty vehicle}, series = {8. Internationale Fachtagung Kraftwerk Batterie : 26. - 27. April 2016, M{\"u}nster, Deutschland}, booktitle = {8. Internationale Fachtagung Kraftwerk Batterie : 26. - 27. April 2016, M{\"u}nster, Deutschland}, year = {2016}, language = {en} } @inproceedings{SchirraBauschatWatmuff2014, author = {Schirra, Julian and Bauschat, J.-Michael and Watmuff, J.H.}, title = {Accurate induced drag prediction for highly non-planar lifting systems}, series = {19th Australasian Fluid Mechanics Conference : 8.-11. Dezember 2014, Melbourne, Australia}, booktitle = {19th Australasian Fluid Mechanics Conference : 8.-11. Dezember 2014, Melbourne, Australia}, pages = {4 Seiten}, year = {2014}, abstract = {The impact of wake model effects is investigated for two highly non-planar lifting systems. Dependent on the geometrical arrangement of the configuration, the wake model shape is found to considerably affect the estimation. Particularly at higher angles of attack, an accurate estimation based on the common linear wake model approaches is involved.}, language = {en} } @inproceedings{NeuJanserKhatibietal.2016, author = {Neu, Eugen and Janser, Frank and Khatibi, Akbar A. and Orifici, Adrian C.}, title = {In-flight vibration-based structural health monitoring of aircraft wings}, series = {30th Congress of the internatonal council of the aeronautical sciences : 25.-30. September 2016, Daejeon, Korea}, booktitle = {30th Congress of the internatonal council of the aeronautical sciences : 25.-30. September 2016, Daejeon, Korea}, pages = {10 Seiten}, year = {2016}, abstract = {This work presents a methodology for automated damage-sensitive feature extraction and anomaly detection under multivariate operational variability for in-flight assessment of wings. The method uses a passive excitation approach, i. e. without the need for artificial actuation. The modal system properties (natural frequencies and damping ratios) are used as damage-sensitive features. Special emphasis is placed on the use of Fiber Bragg Grating (FBG) sensing technology and the consideration of Operational and Environmental Variability (OEV). Measurements from a wind tunnel investigation with a composite cantilever equipped with FBG and piezoelectric sensors are used to successfully detect an impact damage. In addition, the feasibility of damage localisation and severity estimation is evaluated based on the coupling found between damageand OEV-induced feature changes.}, language = {en} } @article{PetersonRoethUibel2017, author = {Peterson, Leif Arne and R{\"o}th, Thilo and Uibel, Thomas}, title = {Einsatz von Holzwerkstoffen in Fahrzeugstrukturen}, series = {Bauen mit Holz}, journal = {Bauen mit Holz}, number = {3}, publisher = {Bruderverlag}, address = {K{\"o}ln}, issn = {0005-6545}, pages = {32 -- 38}, year = {2017}, language = {de} } @inproceedings{PetersonRoethUibel2017, author = {Peterson, Leif Arne and R{\"o}th, Thilo and Uibel, Thomas}, title = {Holzwerkstoffe in Karosseriestrukturen}, series = {Tagungsband Aachener Holzbautagung 2017}, booktitle = {Tagungsband Aachener Holzbautagung 2017}, editor = {Uibel, Thormas and Peterson, Leif Arne and Baumann, Marcus}, issn = {2197-4489}, pages = {34 -- 45}, year = {2017}, language = {de} } @article{PeloniDachwaldCeriotti2017, author = {Peloni, Alessandro and Dachwald, Bernd and Ceriotti, Matteo}, title = {Multiple near-earth asteroid rendezvous mission: Solar-sailing options}, series = {Advances in Space Research}, journal = {Advances in Space Research}, number = {In Press, Corrected Proof}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0273-1177}, doi = {10.1016/j.asr.2017.10.017}, year = {2017}, language = {en} } @incollection{PielenRoethFlatten2018, author = {Pielen, Michael and R{\"o}th, Thilo and Flatten, T.}, title = {Erfolgsfaktoren k{\"u}nftiger Gesch{\"a}ftsmodelle von urbanen, geteilten Mobilit{\"a}tsdienstleistungen}, series = {Mobilit{\"a}t und digitale Transformation. (9. Wissenschaftsforum Mobilit{\"a}t. Tagungsband)}, booktitle = {Mobilit{\"a}t und digitale Transformation. (9. Wissenschaftsforum Mobilit{\"a}t. Tagungsband)}, editor = {Proff, H.}, publisher = {Springer Gabler}, address = {Wiesbaden}, isbn = {978-3-658-20779-3}, doi = {10.1007/978-3-658-20779-3_2}, pages = {435 -- 448}, year = {2018}, abstract = {Digitalisierung bezeichnet die Nutzung großer Datenmengen, die zu einer umfassenden Vernetzung aller Bereiche der Wirtschaft und Gesellschaft f{\"u}hren wird (BMWi, 2015 und {\"a}hnlich K{\"o}hler/Wollschl{\"a}ger, 2014: 79). Sie umfasst die Erhebung von analogen Informationen („Big Data" in einem engen Sinne; z.B. O´Leary, 2013), ihre Speicherung in einem digitaltechnischen System (lokale Speicherung oder „Cloud Computing" durch die Weiterentwickelung des Internets; z.B. Hashem et al., 2015: 101), die Analyse und Interpretation sowie den Transfer in andere Systeme („Internet der Dinge" bzw. „Internet of Things"; z.B. Ashton, 2009).}, language = {de} } @article{BillerbeckBarnatKnutzen2016, author = {Billerbeck, Katrin and Barnat, Miriam and Knutzen, S{\"o}nke}, title = {Kompetenzorientierung auf dem Pr{\"u}fstand. Erprobung von Indikatoren f{\"u}r den Kulturwandel}, series = {Die Hochschullehre}, volume = {2016}, journal = {Die Hochschullehre}, number = {16}, publisher = {WBV Media}, address = {Bielefeld}, issn = {2199-8825}, doi = {10.3278/HSL1616W}, pages = {16}, year = {2016}, abstract = {Der Beitrag fokussiert die Frage nach dem Stand des durch die Bologna-Reform angestoßenen Kulturwandels im Hinblick auf Kompetenzorientierung am Beispiel der Technischen Universit{\"a}t Hamburg (TUHH). An der TUHH wird bereits seit einigen Jahren daran gearbeitet, die Lehre grundlegend neu auszurichten. Hierf{\"u}r setzt das hochschuldidaktische "Zentrum f{\"u}r Lehre und Lernen" (ZLL) verschiedene Maßnahmen ein, wie z.B. eine finanzielle und didaktische Unterst{\"u}tzung von Lehrenden bei der Umstellung ihrer Veranstaltungen, Weiterqualifizierungsangebote und Informationsmaterial. Die Maßnahmen ebenso wie die innovierten Veranstaltungen werden von Lehrenden und Studierenden gut evaluiert. Nach dem Ansatz des Constructive Alignments l{\"a}sst sich jedoch davon ausgehen, dass der Bereich der Pr{\"u}fungen f{\"u}r eine Einsch{\"a}tzung des Status Quo der Kompetenzorientierung besonders relevant ist. Dieser wird deshalb anhand der beiden Kriterien Pr{\"u}fungsformate und Schwierigkeitsstufen von Pr{\"u}fungsaufgaben n{\"a}her beleuchtet, die eng mit der Kompetenzorientierung zusammen h{\"a}ngen. Ergebnisse hierzu aus einer universit{\"a}tsweiten Datenbank zur Studienorganisation sowie aus einer Online-Umfrage unter Studierenden weisen darauf hin, dass das Pr{\"u}fungsformat "Klausur" nach wie vor am st{\"a}rksten verbreitet ist; zugleich sind die Studierenden nach einer Selbsteinsch{\"a}tzung in Pr{\"u}fungen vorrangig mit Aufgaben auf den Taxonomieniveaus "Wiedergeben" und "Anwenden" konfrontiert. Dies l{\"a}sst sich als Hinweis darauf interpretieren, dass es im Hinblick auf eine Kompetenzorientierung in den Pr{\"u}fungen noch weiteren Ver{\"a}nderungsbedarf gibt.}, language = {de} } @inproceedings{BarnatBosse2016, author = {Barnat, Miriam and Bosse, Elke}, title = {The challenge of creating meta-inferences: Combining data representing institutional and individual perspectives on first-year support in higher education}, series = {9th Conference on Social Science Methodology of the International Sociological Association, Leicester, UK}, booktitle = {9th Conference on Social Science Methodology of the International Sociological Association, Leicester, UK}, pages = {1 -- 20}, year = {2016}, language = {en} } @inproceedings{KleineKallweitMichauxetal.2016, author = {Kleine, Harald and Kallweit, Stephan and Michaux, Frank and Havermann, Marc and Olivier, Herbert}, title = {PIV Measurement of Shock Wave Diffraction}, series = {18th International Symposium on Applications of Laser Techniques to Fluid Mechanics, 2016, Lissabon}, booktitle = {18th International Symposium on Applications of Laser Techniques to Fluid Mechanics, 2016, Lissabon}, pages = {1 -- 14}, year = {2016}, language = {en} } @inproceedings{SchleupenEngemannBagherietal.2016, author = {Schleupen, Josef and Engemann, Heiko and Bagheri, Mohsen and Kallweit, Stephan}, title = {The potential of SMART climbing robot combined with a weatherproof cabin for rotor blade maintenance}, series = {17th European Conference on Composite Materials - ECCM, Munich, Germany}, booktitle = {17th European Conference on Composite Materials - ECCM, Munich, Germany}, pages = {1 -- 8}, year = {2016}, language = {en} } @article{BarnatFariaBosse2017, author = {Barnat, Miriam and Faria, Joana Abelha and Bosse, Elke}, title = {Heterogenit{\"a}t und Studierf{\"a}higkeit: Erste Ergebnisse einer L{\"a}ngsschnittbefragung}, series = {Qualit{\"a}t in der Wissenschaft: QiW ; Zeitschrift f{\"u}r Qualit{\"a}tsentwicklung in Forschung, Studium und Administration}, volume = {11}, journal = {Qualit{\"a}t in der Wissenschaft: QiW ; Zeitschrift f{\"u}r Qualit{\"a}tsentwicklung in Forschung, Studium und Administration}, number = {1}, publisher = {UVW Universit{\"a}ts-Verlag Webler}, address = {Bielefeld}, issn = {1860-3041}, pages = {17 -- 24}, year = {2017}, language = {de} } @inproceedings{BarnatKnutzen2017, author = {Barnat, Miriam and Knutzen, S.}, title = {Erfolgsstrategien f{\"u}r organisationales Lernen}, series = {Hochschulwege 2015 : Wie ver{\"a}ndern Projekte die Hochschulen? ; Dokumentation der Tagung in Weimar im M{\"a}rz 2015}, booktitle = {Hochschulwege 2015 : Wie ver{\"a}ndern Projekte die Hochschulen? ; Dokumentation der Tagung in Weimar im M{\"a}rz 2015}, editor = {Mai, Andreas}, publisher = {tredition}, address = {Hamburg}, isbn = {978-3-7439-1763-7}, pages = {91 -- 108}, year = {2017}, language = {de} } @inproceedings{GrundmannMessBieleetal.2017, author = {Grundmann, Jan Thimo and Meß, Jan-Gerd and Biele, Jens and Seefeldt, Patric and Dachwald, Bernd and Spietz, Peter and Grimm, Christian D. and Spr{\"o}witz, Tom and Lange, Caroline and Ulamec, Stephan}, title = {Small spacecraft in small solar system body applications}, series = {IEEE Aerospace Conference 2017, Big Sky, Montana, USA}, booktitle = {IEEE Aerospace Conference 2017, Big Sky, Montana, USA}, organization = {IEEE Aerospace Conference}, isbn = {978-1-5090-1613-6}, doi = {10.1109/AERO.2017.7943626}, pages = {1 -- 20}, year = {2017}, language = {en} } @article{FunkeKeinzKustereretal.2017, author = {Funke, Harald and Keinz, Jan and Kusterer, K. and Haj Ayed, A. and Kazari, M. and Kitajima, J. and Horikawa, A. and Okada, K.}, title = {Development and Testing of a Low NOX Micromix Combustion Chamber for an Industrial Gas Turbine}, series = {International Journal of Gas Turbine, Propulsion and Power Systems}, volume = {9}, journal = {International Journal of Gas Turbine, Propulsion and Power Systems}, number = {1}, issn = {1882-5079}, doi = {10.38036/jgpp.9.1_27}, pages = {27 -- 36}, year = {2017}, abstract = {The Micromix combustion principle, based on cross-flow mixing of air and hydrogen, promises low emission applications in future gas turbines. The Micromix combustion takes place in several hundreds of miniaturized diffusion-type micro-flames. The major advantage is the inherent safety against flash-back and low NOx-emissions due to a very short residence time of reactants in the flame region. The paper gives insight into the Micromix design and scaling procedure for different energy densities and the interaction of scaling laws and key design drivers in gas turbine integration. Numerical studies, experimental testing, gas turbine integration and interface considerations are evaluated. The aerodynamic stabilization of the miniaturized flamelets and the resulting flow field, flame structure and NOx formation are analysed experimentally and numerically. The results show and confirm the successful adaption of the low NOx Micromix characteristics for a range of different nozzle sizes, energy densities and thermal power output.}, language = {de} } @inproceedings{FunkeKeinzHendrick2017, author = {Funke, Harald and Keinz, Jan and Hendrick, P.}, title = {Experimental Evaluation of the Pollutant and Noise Emissions of the GTCP 36-300 Gas Turbine Operated with Kerosene and a Low NOX Micromix Hydrogen Combustor}, series = {7th European Conference for Aeronautics and Space Sciences, EUCASS 2017}, booktitle = {7th European Conference for Aeronautics and Space Sciences, EUCASS 2017}, organization = {7th European Conference for Aeronautics and Space Sciences, EUCASS 2017-125, Milan, Italy, July 2017}, doi = {10.13009/EUCASS2017-125}, pages = {10 Seiten}, year = {2017}, language = {en} } @book{OPUS4-8743, title = {Handbuch der Raumfahrttechnik}, editor = {Ley, Wilfried and Hallmann, Willi and Wittmann, Klaus}, edition = {5. Auflage}, publisher = {Hanser}, address = {M{\"u}nchen}, isbn = {978-3-446-45429-3}, pages = {934 Seiten}, year = {2019}, language = {de} } @inproceedings{GierseKraemerDaabetal.2013, author = {Gierse, Andreas and Kr{\"a}mer, Stefan and Daab, Dominique J. and Hessel, Joana and Baader, Fabian and M{\"u}ller, Brigitte S. and Wagner, Tobias and Gdalewitsch, Georg and Plescher, Engelbert and Pf{\"u}tzenreuter, Lysan}, title = {Experimental in-flight modal-analysis of a sounding rocket structure}, series = {21st ESA Symposium on Rocket and Ballon related Research}, booktitle = {21st ESA Symposium on Rocket and Ballon related Research}, isbn = {9789290922858}, pages = {341 -- 346}, year = {2013}, language = {en} } @incollection{BarnatJaensch2019, author = {Barnat, Miriam and J{\"a}nsch, Vanessa K.}, title = {Forschendes Lernen und Studienerfolg: Die Bedeutung epistemischer Neugier}, series = {Forschendes Lernen in der Studieneingangsphase: Empirische Befunde, Fallbeispiele und individuelle Perspektiven}, booktitle = {Forschendes Lernen in der Studieneingangsphase: Empirische Befunde, Fallbeispiele und individuelle Perspektiven}, publisher = {Springer VS}, address = {Wiesbaden}, isbn = {978-3-658-25312-7}, doi = {10.1007/978-3-658-25312-7_6}, pages = {99 -- 109}, year = {2019}, abstract = {Forschendes Lernen ist dazu geeignet, epistemische Neugier - definiert als Freude an neuen Erkenntnissen - anzuregen und zu befriedigen. Neben der Selbstwirksamkeit zeigt sich die Neugier als relevant f{\"u}r den Studienerfolg. Allerdings ist bisher nicht gekl{\"a}rt, in welcher Beziehung diese beiden Konstrukte zueinanderstehen.}, language = {de} } @incollection{RoethDeutskensKreiskoetheretal.2018, author = {R{\"o}th, Thilo and Deutskens, Christoph and Kreisk{\"o}ther, Kai and Heimes, Heiner Hans and Schittny, Bastian and Ivanescu, Sebastian and Kleine B{\"u}ning, Max and Reinders, Christian and Wessels, Saskia and Haunreiter, Andreas and Reisgen, Uwe and Thiele, Regina and Hameyer, Kay and Doncker, Rik W. de and Sauer, Uwe and Hoek, Hauke van and H{\"u}bner, Mareike and Hennen, Martin and Stolze, Thilo and Vetter, Andreas and Hagedorn, J{\"u}rgen and M{\"u}ller, Dirk and Rewitz, Kai and Wesseling, Mark and Flieger, Bj{\"o}rn}, title = {Entwicklung von elektrofahrzeugspezifischen Systemen}, series = {Elektromobilit{\"a}t}, booktitle = {Elektromobilit{\"a}t}, publisher = {Springer Vieweg}, address = {Berlin, Heidelberg}, isbn = {978-3-662-53137-2}, doi = {10.1007/978-3-662-53137-2_6}, pages = {279 -- 386}, year = {2018}, abstract = {Die Batterie ist eine der absolut zentralen Komponenten des Elektrofahrzeugs. Die serielle Entwicklung und Produktion dieser Batterien und die Verbesserung der Leistungen wird entscheidend f{\"u}r den Erfolg der Elektromobilit{\"a}t sein. Die Batterie ist jedoch nicht das einzige elektrofahrzeugspezifische System, das neu entwickelt, umkonzipiert oder verbessert werden muss. So sind ebenso die Entwicklung der neuen Fahrzeugstruktur sowie des elektrifizierten Antriebsstranges Teil dieses Kapitels. Weiterhin wird ein Blick auf das bedeutende Thema des Thermomanagements geworfen.}, language = {de} } @article{FunkeBeckmannKeinzetal.2019, author = {Funke, Harald and Beckmann, Nils and Keinz, Jan and Abanteriba, Sylvester}, title = {Numerical and Experimental Evaluation of a Dual-Fuel Dry-Low-NOx Micromix Combustor for Industrial Gas Turbine Applications}, series = {Journal of Thermal Science and Engineering Applications}, volume = {11}, journal = {Journal of Thermal Science and Engineering Applications}, number = {1}, publisher = {ASME}, address = {New York}, issn = {19485085}, doi = {10.1115/1.4041495}, pages = {011015}, year = {2019}, language = {en} } @article{SchaelAtanasyanBerdugoetal.2019, author = {Schael, S. and Atanasyan, A. and Berdugo, J. and Bretz, T. and Czupalla, Markus and Dachwald, Bernd and Doetinchem, P. von and Duranti, M. and Gast, H. and Karpinski, W. and Kirn, T. and L{\"u}belsmeyer, K. and Ma{\~n}a, C. and Marrocchesi, P.S. and Mertsch, P. and Moskalenko, I.V. and Schervan, T. and Schluse, M. and Schr{\"o}der, K.-U. and Schultz von Dratzig, A. and Senatore, C. and Spies, L. and Wakely, S.P. and Wlochal, M. and Uglietti, D. and Zimmermann, J.}, title = {AMS-100: The next generation magnetic spectrometer in space - An international science platform for physics and astrophysics at Lagrange point 2}, series = {Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment}, volume = {944}, journal = {Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment}, number = {162561}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0168-9002}, doi = {10.1016/j.nima.2019.162561}, year = {2019}, language = {en} } @inproceedings{GoettenFingerHavermannetal.2019, author = {G{\"o}tten, Falk and Finger, Felix and Havermann, Marc and Braun, Carsten and Marino, Matthew and Bil, Cees}, title = {A highly automated method for simulating airfoil characteristics at low Reynolds number using a RANS - transition approach}, series = {Deutscher Luft- und Raumfahrtkongress - DLRK 2019. Darmstadt, Germany}, booktitle = {Deutscher Luft- und Raumfahrtkongress - DLRK 2019. Darmstadt, Germany}, doi = {10.25967/490026}, pages = {1 -- 14}, year = {2019}, language = {en} } @inproceedings{FingerGoettenBraunetal.2019, author = {Finger, Felix and G{\"o}tten, Falk and Braun, Carsten and Bil, Cees}, title = {Mass, Primary Energy, and Cost - The Impact of Optimization Objectives on the Initial Sizing of Hybrid-Electric General Aviation Aircraft}, series = {Deutscher Luft- und Raumfahrtkongress 2019, DLRK 2019. Darmstadt, Germany}, booktitle = {Deutscher Luft- und Raumfahrtkongress 2019, DLRK 2019. Darmstadt, Germany}, doi = {10.25967/490012}, pages = {1 -- 17}, year = {2019}, language = {en} } @inproceedings{GoettenFinger2019, author = {G{\"o}tten, Falk and Finger, Felix}, title = {Conceptual Design of a Modular 150 kg Vertical Take-off and Landing Unmanned Aerial Vehicle}, series = {Deutscher Luft- und Raumfahrtkongress - DLRK 2019. Darmstadt, Germany}, booktitle = {Deutscher Luft- und Raumfahrtkongress - DLRK 2019. Darmstadt, Germany}, pages = {1 -- 10}, year = {2019}, language = {en} } @phdthesis{Frotscher2016, author = {Frotscher, Ralf}, title = {Electromechanical modeling and simulation of thin cardiac tissue constructs - smoothed FEM applied to a biomechanical plate problem}, year = {2016}, language = {en} } @article{SmithKotliarLammertynetal.2020, author = {Smith, Wayne and Kotliar, Konstantin and Lammertyn, Leandi and Ramoshaba, Nthai E. and Vilser, Walthard and Huisman, Hugo W. and Schutte, Aletta E.}, title = {Retinal vessel caliber and caliber responses in true normotensive black and white adults: The African-PREDICT study}, series = {Microvascular Research}, volume = {128}, journal = {Microvascular Research}, number = {Article 103937}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0026-2862}, doi = {10.1016/j.mvr.2019.103937}, year = {2020}, abstract = {Purpose Globally, a detrimental shift in cardiovascular disease risk factors and a higher mortality level are reported in some black populations. The retinal microvasculature provides early insight into the pathogenesis of systemic vascular diseases, but it is unclear whether retinal vessel calibers and acute retinal vessel functional responses differ between young healthy black and white adults. Methods We included 112 black and 143 white healthy normotensive adults (20-30 years). Retinal vessel calibers (central retinal artery and vein equivalent (CRAE and CRVE)) were calculated from retinal images and vessel caliber responses to flicker light induced provocation (FLIP) were determined. Additionally, ambulatory blood pressure (BP), anthropometry and blood samples were collected. Results The groups displayed similar 24 h BP profiles and anthropometry (all p > .24). Black participants demonstrated a smaller CRAE (158 ± 11 vs. 164 ± 11 MU, p < .001) compared to the white group, whereas CRVE was similar (p = .57). In response to FLIP, artery maximal dilation was greater in the black vs. white group (5.6 ± 2.1 vs. 3.3 ± 1.8\%; p < .001). Conclusions Already at a young age, healthy black adults showed narrower retinal arteries relative to the white population. Follow-up studies are underway to show if this will be related to increased risk for hypertension development. The reason for the larger vessel dilation responses to FLIP in the black population is unclear and warrants further investigation.}, language = {en} } @article{FingerBraunBil2020, author = {Finger, Felix and Braun, Carsten and Bil, Cees}, title = {Impact of Battery Performance on the Initial Sizing of Hybrid-Electric General Aviation Aircraft}, series = {Journal of Aerospace Engineering}, volume = {33}, journal = {Journal of Aerospace Engineering}, number = {3}, publisher = {ASCE}, address = {Reston, Va.}, issn = {1943-5525}, doi = {10.1061/(ASCE)AS.1943-5525.0001113}, year = {2020}, abstract = {Studies suggest that hybrid-electric aircraft have the potential to generate fewer emissions and be inherently quieter when compared to conventional aircraft. By operating combustion engines together with an electric propulsion system, synergistic benefits can be obtained. However, the performance of hybrid-electric aircraft is still constrained by a battery's energy density and discharge rate. In this paper, the influence of battery performance on the gross mass for a four-seat general aviation aircraft with a hybrid-electric propulsion system is analyzed. For this design study, a high-level approach is chosen, using an innovative initial sizing methodology to determine the minimum required aircraft mass for a specific set of requirements and constraints. Only the peak-load shaving operational strategy is analyzed. Both parallel- and serial-hybrid propulsion configurations are considered for two different missions. The specific energy of the battery pack is varied from 200 to 1,000 W⋅h/kg, while the discharge time, and thus the normalized discharge rating (C-rating), is varied between 30 min (2C discharge rate) and 2 min (30C discharge rate). With the peak-load shaving operating strategy, it is desirable for hybrid-electric aircraft to use a light, low capacity battery system to boost performance. For this case, the battery's specific power rating proved to be of much higher importance than for full electric designs, which have high capacity batteries. Discharge ratings of 20C allow a significant take-off mass reduction aircraft. The design point moves to higher wing loadings and higher levels of hybridization if batteries with advanced technology are used.}, language = {en} } @inproceedings{KreyerMuellerEsch2020, author = {Kreyer, J{\"o}rg and M{\"u}ller, Marvin and Esch, Thomas}, title = {A Map-Based Model for the Determination of Fuel Consumption for Internal Combustion Engines as a Function of Flight Altitude}, publisher = {DGLR}, address = {Bonn}, doi = {10.25967/490162}, pages = {13 Seiten}, year = {2020}, abstract = {In addition to very high safety and reliability requirements, the design of internal combustion engines (ICE) in aviation focuses on economic efficiency. The objective must be to design the aircraft powertrain optimized for a specific flight mission with respect to fuel consumption and specific engine power. Against this background, expert tools provide valuable decision-making assistance for the customer. In this paper, a mathematical calculation model for the fuel consumption of aircraft ICE is presented. This model enables the derivation of fuel consumption maps for different engine configurations. Depending on the flight conditions and based on these maps, the current and the integrated fuel consumption for freely definable flight emissions is calculated. For that purpose, an interpolation method is used, that has been optimized for accuracy and calculation time. The mission boundary conditions flight altitude and power requirement of the ICE form the basis for this calculation. The mathematical fuel consumption model is embedded in a parent program. This parent program presents the simulated fuel consumption by means of an example flight mission for a representative airplane. The focus of the work is therefore on reproducing exact consumption data for flight operations. By use of the empirical approaches according to Gagg-Farrar [1] the power and fuel consumption as a function of the flight altitude are determined. To substantiate this approaches, a 1-D ICE model based on the multi-physical simulation tool GT-Suite® has been created. This 1-D engine model offers the possibility to analyze the filling and gas change processes, the internal combustion as well as heat and friction losses for an ICE under altitude environmental conditions. Performance measurements on a dynamometer at sea level for a naturally aspirated ICE with a displacement of 1211 ccm used in an aviation aircraft has been done to validate the 1-D ICE model. To check the plausibility of the empirical approaches with respect to the fuel consumption and performance adjustment for the flight altitude an analysis of the ICE efficiency chain of the 1-D engine model is done. In addition, a comparison of literature and manufacturer data with the simulation results is presented.}, language = {en} } @inproceedings{FingerGoettenBraunetal.2019, author = {Finger, Felix and G{\"o}tten, Falk and Braun, Carsten and Bil, Cees}, title = {Cost Estimation Methods for Hybrid-Electric General Aviation Aircraft}, series = {Asia Pacific International Symposium on Aerospace Technology. APISAT 2019}, booktitle = {Asia Pacific International Symposium on Aerospace Technology. APISAT 2019}, pages = {1 -- 13}, year = {2019}, language = {en} } @inproceedings{FingerBraunBil2020, author = {Finger, Felix and Braun, Carsten and Bil, Cees}, title = {Comparative assessment of parallel-hybrid-electric propulsion systems for four different aircraft}, series = {AIAA Scitech 2020 Forum}, booktitle = {AIAA Scitech 2020 Forum}, doi = {10.2514/6.2020-1502}, pages = {15 Seiten}, year = {2020}, abstract = {As battery technologies advance, electric propulsion concepts are on the edge of disrupting aviation markets. However, until electric energy storage systems are ready to allow fully electric aircraft, the combination of combustion engine and electric motor as a hybrid-electric propulsion system seems to be a promising intermediate solution. Consequently, the design space for future aircraft is expanded considerably, as serial-hybrid-, parallel-hybrid-, fully-electric, and conventional propulsion systems must all be considered. While the best propulsion system depends on a multitude of requirements and considerations, trends can be observed for certain types of aircraft and certain types of missions. This paper provides insight into some factors that drive a new design towards either conventional or hybrid propulsion systems. General aviation aircraft, VTOL air taxis, transport aircraft, and UAVs are chosen as case studies. Typical missions for each class are considered, and the aircraft are analyzed regarding their take-off mass and primary energy consumption. For these case studies, a high-level approach is chosen, using an initial sizing methodology. Results indicate that hybrid-electric propulsion systems should be considered if the propulsion system is sized by short-duration power constraints (e.g. take-off, climb). However, if the propulsion system is sized by a continuous power requirement (e.g. cruise), hybrid-electric systems offer hardly any benefit.}, language = {en} } @inproceedings{GoettenFingerMarinoetal.2019, author = {G{\"o}tten, Falk and Finger, Felix and Marino, Matthew and Bil, Cees and Havermann, Marc and Braun, Carsten}, title = {A review of guidelines and best practices for subsonic aerodynamic simulations using RANS CFD}, series = {Asia-Pacific International Symposium on Aerospace Technology (APISAT), At Gold Coast, Australia, 04. - 06. Dezember 2019}, booktitle = {Asia-Pacific International Symposium on Aerospace Technology (APISAT), At Gold Coast, Australia, 04. - 06. Dezember 2019}, isbn = {978-1-925627-40-4}, pages = {19 Seiten}, year = {2019}, language = {de} } @inproceedings{FingerdeVriesVosetal.2020, author = {Finger, Felix and de Vries, Reynard and Vos, Roelof and Braun, Carsten and Bil, Cees}, title = {A comparison of hybrid-electric aircraft sizing methods}, series = {AIAA Scitech 2020 Forum}, booktitle = {AIAA Scitech 2020 Forum}, doi = {10.2514/6.2020-1006}, pages = {31 Seiten}, year = {2020}, abstract = {The number of case studies focusing on hybrid-electric aircraft is steadily increasing, since these configurations are thought to lead to lower operating costs and environmental impact than traditional aircraft. However, due to the lack of reference data of actual hybrid-electric aircraft, in most cases, the design tools and results are difficult to validate. In this paper, two independently developed approaches for hybrid-electric conceptual aircraft design are compared. An existing 19-seat commuter aircraft is selected as the conventional baseline, and both design tools are used to size that aircraft. The aircraft is then re-sized under consideration of hybrid-electric propulsion technology. This is performed for parallel, serial, and fully-electric powertrain architectures. Finally, sensitivity studies are conducted to assess the validity of the basic assumptions and approaches regarding the design of hybrid-electric aircraft. Both methods are found to predict the maximum take-off mass (MTOM) of the reference aircraft with less than 4\% error. The MTOM and payload-range energy efficiency of various (hybrid-) electric configurations are predicted with a maximum difference of approximately 2\% and 5\%, respectively. The results of this study confirm a correct formulation and implementation of the two design methods, and the data obtained can be used by researchers to benchmark and validate their design tools.}, language = {en} } @inproceedings{StrieganStruthDickhoffetal.2019, author = {Striegan, Constantin J. D. and Struth, Benjamin and Dickhoff, Jens and Kusterer, Karsten and Funke, Harald and Bohn, Dieter}, title = {Numerical Simulations of the Micromix DLN Hydrogen Combustion Technology with LES and Comparison to Results of RANS and Experimental Data}, series = {Proceedings of International Gas Turbine Congress 2019 Tokyo, November 17-22, 2019, Tokyo, Japan.}, booktitle = {Proceedings of International Gas Turbine Congress 2019 Tokyo, November 17-22, 2019, Tokyo, Japan.}, isbn = {978-4-89111-010-9}, pages = {1 -- 9}, year = {2019}, language = {en} } @inproceedings{FingerKhalsaKreyeretal.2019, author = {Finger, Felix and Khalsa, R. and Kreyer, J{\"o}rg and Mayntz, Joscha and Braun, Carsten and Dahmann, Peter and Esch, Thomas and Kemper, Hans and Schmitz, O. and Bragard, Michael}, title = {An approach to propulsion system modelling for the conceptual design of hybrid-electric general aviation aircraft}, series = {Deutscher Luft- und Raumfahrtkongress 2019, 30.9.-2.10.2019, Darmstadt}, booktitle = {Deutscher Luft- und Raumfahrtkongress 2019, 30.9.-2.10.2019, Darmstadt}, pages = {15 Seiten}, year = {2019}, abstract = {In this paper, an approach to propulsion system modelling for hybrid-electric general aviation aircraft is presented. Because the focus is on general aviation aircraft, only combinations of electric motors and reciprocating combustion engines are explored. Gas turbine hybrids will not be considered. The level of the component's models is appropriate for the conceptual design stage. They are simple and adaptable, so that a wide range of designs with morphologically different propulsive system architectures can be quickly compared. Modelling strategies for both mass and efficiency of each part of the propulsion system (engine, motor, battery and propeller) will be presented.}, language = {en} } @inproceedings{QuitterMarinoBauschat2019, author = {Quitter, Julius and Marino, Matthew and Bauschat, J.-Michael}, title = {Highly Non-Planar Aircraft Configurations: Estimation of Flight Mechanical Derivatives Using Low-Order Methods}, series = {Deutscher Luft- und Raumfahrtkongress 2019, DLRK 2019. Darmstadt, Germany}, booktitle = {Deutscher Luft- und Raumfahrtkongress 2019, DLRK 2019. Darmstadt, Germany}, pages = {10 Seiten}, year = {2019}, language = {en} } @article{KhayyamJamaliBabHadiasharetal.2020, author = {Khayyam, Hamid and Jamali, Ali and Bab-Hadiashar, Alireza and Esch, Thomas and Ramakrishna, Seeram and Jalil, Mahdi and Naebe, Minoo}, title = {A Novel Hybrid Machine Learning Algorithm for Limited and Big Data Modelling with Application in Industry 4.0}, series = {IEEE Access}, journal = {IEEE Access}, publisher = {IEEE}, address = {New York, NY}, isbn = {2169-3536}, doi = {10.1109/ACCESS.2020.2999898}, pages = {1 -- 12}, year = {2020}, abstract = {To meet the challenges of manufacturing smart products, the manufacturing plants have been radically changed to become smart factories underpinned by industry 4.0 technologies. The transformation is assisted by employment of machine learning techniques that can deal with modeling both big or limited data. This manuscript reviews these concepts and present a case study that demonstrates the use of a novel intelligent hybrid algorithms for Industry 4.0 applications with limited data. In particular, an intelligent algorithm is proposed for robust data modeling of nonlinear systems based on input-output data. In our approach, a novel hybrid data-driven combining the Group-Method of Data-Handling and Singular-Value Decomposition is adapted to find an offline deterministic model combined with Pareto multi-objective optimization to overcome the overfitting issue. An Unscented-Kalman-Filter is also incorporated to update the coefficient of the deterministic model and increase its robustness against data uncertainties. The effectiveness of the proposed method is examined on a set of real industrial measurements.}, language = {en} } @article{HailerWeberNevelingetal.2020, author = {Hailer, Benjamin and Weber, Tobias and Neveling, Sebastian and Dera, Samuel and Arent, Jan-Christoph and Middendorf, Peter}, title = {Development of a test device to determine the frictional behavior between honeycomb and prepreg layers under realistic manufacturing conditions}, series = {Journal of Sandwich Structures \& Materials}, journal = {Journal of Sandwich Structures \& Materials}, number = {Volume 23, Issue 7}, publisher = {Sage}, address = {London}, issn = {1530-7972}, doi = {10.1177/1099636220923986}, pages = {3017 -- 3043}, year = {2020}, abstract = {In the friction tests between honeycomb with film adhesive and prepreg, the relative displacement occurs between the film adhesive and the prepreg. The film adhesive does not shift relative to the honeycomb. This is consistent with the core crush behavior where the honeycomb moves together with the film adhesive, as can be seen in Figure 2(a). The pull-through forces of the friction measurements between honeycomb and prepreg at 1 mm deformation are plotted in Figure 17(a). While the friction at 100°C is similar to the friction at 120°C, it decreases significantly at 130°C and exhibits a minimum at 140°C. At 150°C, the friction rises again slightly and then sharply at 160°C. Since the viscosity of the M18/1 prepreg resin drops significantly before it cures [23], the minimum friction at 140°C could result from a minimum viscosity of the mixture of prepreg resin and film adhesive before the bond subsequently cures. Figure 17(b) shows the mean value curve of the friction measurements at 140°C. The error bars, which represent the standard deviation, reveal the good repeatability of the tests. The force curve is approximately horizontal between 1 mm and 2 mm. The friction then slightly rises. As with interlaminar friction measurements, this could be due to the fact that resin is removed by friction and the proportion of boundary lubrication increases. Figure 18 shows the surfaces after the friction measurement. The honeycomb cell walls are clearly visible in the film adhesive. There are areas where the film adhesive is completely removed and the carrier material of the film adhesive becomes visible. In addition, the viscosity of the resin changes as the curing progresses during the friction test. This can also affect the force-displacement curve.}, language = {en} } @inproceedings{EnglhardWeberArent2021, author = {Englhard, Markus and Weber, Tobias and Arent, Jan-Christoph}, title = {Efficiency enhancement for CFRP-Prepregautoclave manufacturing by means of simulation-assisted loading optimization}, series = {Proceedings of SAMPE Europe Conference 2021}, booktitle = {Proceedings of SAMPE Europe Conference 2021}, pages = {8 Seiten}, year = {2021}, abstract = {A new method for improved autoclave loading within the restrictive framework of helicopter manufacturing is proposed. It is derived from experimental and numerical studies of the curing process and aims at optimizing tooling positions in the autoclave for fast and homogeneous heat-up. The mold positioning is based on two sets of information. The thermal properties of the molds, which can be determined via semi-empirical thermal simulation. The second information is a previously determined distribution of heat transfer coefficients inside the autoclave. Finally, an experimental proof of concept is performed to show a cycle time reduction of up to 31\% using the proposed methodology.}, language = {en} } @article{PeloniCeriottiDachwald2016, author = {Peloni, Alessandro and Ceriotti, Matteo and Dachwald, Bernd}, title = {Solar-sail trajectory design for a multiple near-earth-asteroid rendezvous mission}, series = {Journal of Guidance, Control, and Dynamics}, volume = {39}, journal = {Journal of Guidance, Control, and Dynamics}, number = {12}, publisher = {AIAA}, address = {Reston, Va.}, issn = {0731-5090}, doi = {10.2514/1.G000470}, pages = {2712 -- 2724}, year = {2016}, abstract = {The scientific interest for near-Earth asteroids as well as the interest in potentially hazardous asteroids from the perspective of planetary defense led the space community to focus on near-Earth asteroid mission studies. A multiple near-Earth asteroid rendezvous mission with close-up observations of several objects can help to improve the characterization of these asteroids. This work explores the design of a solar-sail spacecraft for such a mission, focusing on the search of possible sequences of encounters and the trajectory optimization. This is done in two sequential steps: a sequence search by means of a simplified trajectory model and a set of heuristic rules based on astrodynamics, and a subsequent optimization phase. A shape-based approach for solar sailing has been developed and is used for the first phase. The effectiveness of the proposed approach is demonstrated through a fully optimized multiple near-Earth asteroid rendezvous mission. The results show that it is possible to visit five near-Earth asteroids within 10 years with near-term solar-sail technology.}, language = {en} } @inproceedings{HauggKreyerKemperetal.2020, author = {Haugg, Albert Thomas and Kreyer, J{\"o}rg and Kemper, Hans and Hatesuer, Katerina and Esch, Thomas}, title = {Heat exchanger for ORC. adaptability and optimisation potentials}, series = {IIR International Rankine 2020 Conference}, booktitle = {IIR International Rankine 2020 Conference}, doi = {10.18462/iir.rankine.2020.1224}, pages = {10 Seiten}, year = {2020}, abstract = {The recovery of waste heat requires heat exchangers to extract it from a liquid or gaseous medium into another working medium, a refrigerant. In Organic Rankine Cycles (ORC) on Combustion Engines there are two major heat sources, the exhaust gas and the water/glycol fluid from the engine's cooling circuit. A heat exchanger design must be adapted to the different requirements and conditions resulting from the heat sources, fluids, system configurations, geometric restrictions, and etcetera. The Stacked Shell Cooler (SSC) is a new and very specific design of a plate heat exchanger, created by AKG, which allows with a maximum degree of freedom the optimization of heat exchange rate and the reduction of the related pressure drop. This optimization in heat exchanger design for ORC systems is even more important, because it reduces the energy consumption of the system and therefore maximizes the increase in overall efficiency of the engine.}, language = {en} } @article{Maurischat2022, author = {Maurischat, Andreas}, title = {Algebraic independence of the Carlitz period and its hyperderivatives}, series = {Journal of Number Theory}, volume = {240}, journal = {Journal of Number Theory}, publisher = {Elsevier}, address = {Orlando, Fla.}, issn = {0022-314X}, doi = {10.1016/j.jnt.2022.01.006}, pages = {145 -- 162}, year = {2022}, language = {en} } @incollection{HebelHerrmannRitzetal.2022, author = {Hebel, Christoph and Herrmann, Ulf and Ritz, Thomas and R{\"o}th, Thilo and Anthrakidis, Anette and B{\"o}ker, J{\"o}rg and Franzke, Till and Grodzki, Thomas and Merkens, Torsten and Sch{\"o}ttler, Mirjam}, title = {FlexSHARE - Methodisches Framework zur innovativen Gestaltung der urbanen Mobilit{\"a}t durch Sharing- Angebote}, series = {Transforming Mobility - What Next?}, booktitle = {Transforming Mobility - What Next?}, publisher = {Springer Gabler}, address = {Wiesbaden}, isbn = {978-3-658-36429-8}, doi = {10.1007/978-3-658-36430-4_10}, pages = {153 -- 169}, year = {2022}, abstract = {Das Ziel des INTERREG-Projektes „SHAREuregio" (FKZ: 34.EFRE-0300134) ist es, grenz{\"u}berschreitende Mobilit{\"a}t in der Euregio Rhein-Maas-Nord zu erm{\"o}glichen und zu f{\"o}rdern. Dazu soll ein elektromobiles Car- und Bikesharing- System entwickelt und in der Stadt M{\"o}nchengladbach, im Kreis Viersen sowie in den Gemeinden Roermond und Venlo (beide NL) zusammen mit den Partnern Wirtschaftsf{\"o}rderung M{\"o}nchengladbach, Wirtschaftsf{\"o}rderung f{\"u}r den Kreis Viersen, NEW AG, Goodmoovs (NL), Greenflux (NL) und der FH Aachen implementiert werden. Zun{\"a}chst richtet sich das Angebot, bestehend aus 40 Elektroautos und 40 Elektrofahrr{\"a}dern, an Unternehmen und wird nach einer Erprobungsphase, mit einer gr{\"o}ßeren Anzahl an Fahrzeugen, auch f{\"u}r Privatpersonen verf{\"u}gbar gemacht werden. Die Fahrzeuge stehen bei den jeweiligen Anwendungspartnern in Deutschland und den Niederlanden. Im Rahmen dieses Projektes hat die FH Aachen „FlexSHARE" entwickelt - ein methodisches Framework zur innovativen Gestaltung urbaner Sharing- Angebote. Das Framework erm{\"o}glicht es, anhand von messbaren Kenngr{\"o}ßen, bedarfsgerechte und auf die Region abgestimmte Sharing-Systeme zu entwickeln.}, language = {de} } @incollection{BauschatBennerKlingeetal.2022, author = {Bauschat, J.-Michael and Benner, Miriam and Klinge, Henner and Ziegler, Simon}, title = {Urbane Mobilit{\"a}t entdeckt die 3. Dimension}, series = {Transforming Mobility - What Next?}, booktitle = {Transforming Mobility - What Next?}, publisher = {Springer Gabler}, address = {Wiesbaden}, isbn = {978-3-658-36429-8}, doi = {10.1007/978-3-658-36430-4_53}, pages = {895 -- 916}, year = {2022}, abstract = {Der Themenkomplex urbane Mobilit{\"a}t ist getrieben durch den Verkehrsinfarkt in Ballungszentren, durch Luftverschmutzung und L{\"a}rm, sowie den Trend zum Leben in der Stadt in den st{\"a}dteplanerischen Fokus ger{\"u}ckt. Emissionsneutrale Antriebskonzepte in der Luftfahrt f{\"u}hren zu Ans{\"a}tzen Flugger{\"a}te einzusetzen, die batteriegetrieben vertikal aufsteigen und landen k{\"o}nnen. Flugphysikalisch und energetisch ist diese Technik nur dann sinnvoll, wenn es zwingende Gr{\"u}nde gibt (z.B. Rettungseins{\"a}tze), daher wird der flugphysikalische Hintergrund prinzipiell erl{\"a}utert. Es werden einige aktuelle Lufttransportkonzepte f{\"u}r eine urbane Personenbef{\"o}rderung vorgestellt. Sollte es verst{\"a}rkt zu Lufttransport {\"u}ber St{\"a}dten kommen, m{\"u}ssen betroffene Luftr{\"a}ume geordnet und {\"u}berwacht werden. Wie kompatibel Lufttransportsysteme mit den heute bereits relevanten urbanen Bef{\"o}rderungsmitteln sein m{\"u}ssen, wird kritisch diskutiert. Abschließend werden die Aspekte Akzeptanz durch die Kunden und Wirtschaftlichkeit ebenso angerissen, wie die hochproblematische Rohstoffgewinnung, die Entsorgung und das Recycling von Batterien.}, language = {de} } @inproceedings{FunkeBeckmannKeinzetal.2017, author = {Funke, Harald and Beckmann, Nils and Keinz, Jan and Abanteriba, Sylvester}, title = {Numerical and Experimental Evaluation of a Dual-Fuel Dry-Low-NOx Micromix Combustor for Industrial Gas Turbine Applications}, series = {Proceedings of the ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. Volume 4B: Combustion, Fuels and Emissions. Charlotte, North Carolina, USA. June 26-30, 2017}, booktitle = {Proceedings of the ASME Turbo Expo 2017: Turbomachinery Technical Conference and Exposition. Volume 4B: Combustion, Fuels and Emissions. Charlotte, North Carolina, USA. June 26-30, 2017}, publisher = {ASME}, address = {New York}, isbn = {978-0-7918-5085-5}, doi = {10.1115/GT2017-64795}, year = {2017}, abstract = {The Dry-Low-NOx (DLN) Micromix combustion technology has been developed originally as a low emission alternative for industrial gas turbine combustors fueled with hydrogen. Currently the ongoing research process targets flexible fuel operation with hydrogen and syngas fuel. The non-premixed combustion process features jet-in-crossflow-mixing of fuel and oxidizer and combustion through multiple miniaturized flames. The miniaturization of the flames leads to a significant reduction of NOx emissions due to the very short residence time of reactants in the flame. The paper presents the results of a numerical and experimental combustor test campaign. It is conducted as part of an integration study for a dual-fuel (H2 and H2/CO 90/10 Vol.\%) Micromix combustion chamber prototype for application under full scale, pressurized gas turbine conditions in the auxiliary power unit Honeywell Garrett GTCP 36-300. In the presented experimental studies, the integration-optimized dual-fuel Micromix combustor geometry is tested at atmospheric pressure over a range of gas turbine operating conditions with hydrogen and syngas fuel. The experimental investigations are supported by numerical combustion and flow simulations. For validation, the results of experimental exhaust gas analyses are applied. Despite the significantly differing fuel characteristics between pure hydrogen and hydrogen-rich syngas the evaluated dual-fuel Micromix prototype shows a significant low NOx performance and high combustion efficiency. The combustor features an increased energy density that benefits manufacturing complexity and costs.}, language = {en} } @inproceedings{StrieganHajAyedFunkeetal.2017, author = {Striegan, C. and Haj Ayed, A. and Funke, Harald and Loechle, S. and Kazari, M. and Horikawa, A. and Okada, K. and Koga, K.}, title = {Numerical combustion and heat transfer simulations and validation for a hydrogen fueled "micromix" test combustor in industrial gas turbine applications}, series = {Proceedings of the ASME Turbo Expo}, booktitle = {Proceedings of the ASME Turbo Expo}, number = {Volume Part F130041-4B, 2017}, isbn = {978-079185085-5}, doi = {10.1115/GT2017-64719}, year = {2017}, language = {en} } @book{JanserHavermannHoeveleretal.2016, author = {Janser, Frank and Havermann, Marc and Hoeveler, Bastian and Hertz, Cyril}, title = {Inkompressible Profil- und Tragfl{\"u}gelaerodynamik}, series = {Str{\"o}mungslehre und Aerodynamik ; Band 2}, journal = {Str{\"o}mungslehre und Aerodynamik ; Band 2}, edition = {1. Auflage}, publisher = {Verlagshaus Mainz GmbH}, address = {Aachen}, isbn = {978-3-8107-0261-6}, pages = {XIII, 208 Seiten}, year = {2016}, language = {de} } @inproceedings{LudowicyRingsFingeretal.2018, author = {Ludowicy, Jonas and Rings, Ren{\´e} and Finger, Felix and Braun, Carsten}, title = {Sizing Studies of Light Aircraft with Serial Hybrid Propulsion Systems}, series = {Luft- und Raumfahrt - Digitalisierung und Vernetzung : Deutscher Luft- und Raumfahrtkongress 2018. 4. - 6. September 2018 - Friedrichshafen}, booktitle = {Luft- und Raumfahrt - Digitalisierung und Vernetzung : Deutscher Luft- und Raumfahrtkongress 2018. 4. - 6. September 2018 - Friedrichshafen}, pages = {11 S.}, year = {2018}, language = {en} } @inproceedings{FingerGoettenBraun2018, author = {Finger, Felix and G{\"o}tten, Falk and Braun, Carsten}, title = {Initial Sizing for a Family of Hybrid-Electric VTOL General Aviation Aircraft}, series = {67. Deutscher Luft- und Raumfahrtkongress 2018}, booktitle = {67. Deutscher Luft- und Raumfahrtkongress 2018}, pages = {14 S.}, year = {2018}, language = {en} } @inproceedings{LudowicyRingsFingeretal.2018, author = {Ludowicy, Jonas and Rings, Ren{\´e} and Finger, Felix and Braun, Carsten}, title = {Sizing Studies of Light Aircraft with Parallel Hybrid Propulsion Systems}, series = {Deutscher Luft- und Raumfahrtkongress 2018}, booktitle = {Deutscher Luft- und Raumfahrtkongress 2018}, doi = {10.25967/480227}, pages = {15 S.}, year = {2018}, 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{TekinAshikagaHorikawaetal.2018, author = {Tekin, Nurettin and Ashikaga, Mitsugu and Horikawa, Atsushi and Funke, Harald}, title = {Enhancement of fuel flexibility of industrial gas turbines by development of innovative hydrogen combustion systems}, series = {Gas for energy}, journal = {Gas for energy}, number = {2}, publisher = {Vulkan-Verlag}, address = {Essen}, pages = {4}, year = {2018}, abstract = {For fuel flexibility enhancement hydrogen represents a possible alternative gas turbine fuel within future low emission power generation, in case of hydrogen production by the use of renewable energy sources such as wind energy or biomass. Kawasaki Heavy Industries, Ltd. (KHI) has research and development projects for future hydrogen society; production of hydrogen gas, refinement and liquefaction for transportation and storage, and utilization with gas turbine / gas engine for the generation of electricity. In the development of hydrogen gas turbines, a key technology is the stable and low NOx hydrogen combustion, especially Dry Low Emission (DLE) or Dry Low NOx (DLN) hydrogen combustion. Due to the large difference in the physical properties of hydrogen compared to other fuels such as natural gas, well established gas turbine combustion systems cannot be directly applied for DLE hydrogen combustion. Thus, the development of DLE hydrogen combustion technologies is an essential and challenging task for the future of hydrogen fueled gas turbines. The DLE Micro-Mix combustion principle for hydrogen fuel has been in development for many years to significantly reduce NOx emissions. This combustion principle is based on cross-flow mixing of air and gaseous hydrogen which reacts in multiple miniaturized "diffusion-type" flames. The major advantages of this combustion principle are the inherent safety against flashback and the low NOx-emissions due to a very short residence time of the reactants in the flame region of the micro-flames.}, language = {en} } @inproceedings{FingerBraunBil2019, author = {Finger, Felix and Braun, Carsten and Bil, Cees}, title = {Impact of Engine Failure Constraints on the Initial Sizing of Hybrid-Electric GA Aircraft}, series = {AIAA Scitech 2019 Forum}, booktitle = {AIAA Scitech 2019 Forum}, doi = {10.2514/6.2019-1812}, year = {2019}, language = {en} } @article{ThomaRavi2019, author = {Thoma, Andreas and Ravi, Sridhar}, title = {Significance of parallel computing on the performance of Digital Image Correlation algorithms in MATLAB}, pages = {1 -- 17}, year = {2019}, abstract = {Digital Image Correlation (DIC) is a powerful tool used to evaluate displacements and deformations in a non-intrusive manner. By comparing two images, one of the undeformed reference state of a specimen and another of the deformed target state, the relative displacement between those two states is determined. DIC is well known and often used for post-processing analysis of in-plane displacements and deformation of specimen. Increasing the analysis speed to enable real-time DIC analysis will be beneficial and extend the field of use of this technique. Here we tested several combinations of the most common DIC methods in combination with different parallelization approaches in MATLAB and evaluated their performance to determine whether real-time analysis is possible with these methods. To reflect improvements in computing technology different hardware settings were also analysed. We found that implementation problems can reduce the efficiency of a theoretically superior algorithm such that it becomes practically slower than a suboptimal algorithm. The Newton-Raphson algorithm in combination with a modified Particle Swarm algorithm in parallel image computation was found to be most effective. This is contrary to theory, suggesting that the inverse-compositional Gauss-Newton algorithm is superior. As expected, the Brute Force Search algorithm is the least effective method. We also found that the correct choice of parallelization tasks is crucial to achieve improvements in computing speed. A poorly chosen parallelisation approach with high parallel overhead leads to inferior performance. Finally, irrespective of the computing mode the correct choice of combinations of integerpixel and sub-pixel search algorithms is decisive for an efficient analysis. Using currently available hardware realtime analysis at high framerates remains an aspiration.}, language = {en} } @inproceedings{WaldmannVeraDachwaldetal.2018, author = {Waldmann, Christoph and Vera, Jean-Pierre de and Dachwald, Bernd and Strasdeit, Henry and Sohl, Frank and Hanff, Hendrik and Kowalski, Julia and Heinen, Dirk and Macht, Sabine and Bestmann, Ulf and Meckel, Sebastian and Hildebrandt, Marc and Funke, Oliver and Gehrt, Jan-J{\"o}ran}, title = {Search for life in ice-covered oceans and lakes beyond Earth}, series = {2018 IEEE/OES Autonomous Underwater Vehicle Workshop, Proceedings November 2018, Article number 8729761}, booktitle = {2018 IEEE/OES Autonomous Underwater Vehicle Workshop, Proceedings November 2018, Article number 8729761}, doi = {10.1109/AUV.2018.8729761}, year = {2018}, abstract = {The quest for life on other planets is closely connected with the search for water in liquid state. Recent discoveries of deep oceans on icy moons like Europa and Enceladus have spurred an intensive discussion about how these waters can be accessed. The challenge of this endeavor lies in the unforeseeable requirements on instrumental characteristics both with respect to the scientific and technical methods. The TRIPLE/nanoAUV initiative is aiming at developing a mission concept for exploring exo-oceans and demonstrating the achievements in an earth-analogue context, exploring the ocean under the ice shield of Antarctica and lakes like Dome-C on the Antarctic continent.}, language = {en} } @inproceedings{HoevelerJanser2016, author = {Hoeveler, Bastian and Janser, Frank}, title = {The aerodynamically optimized design of a fan-in-wing duct}, series = {Applied Aerodynamics Research Conference 2016, Bristol, GB, Jul 19-21, 2016}, booktitle = {Applied Aerodynamics Research Conference 2016, Bristol, GB, Jul 19-21, 2016}, isbn = {1-85768-371-4}, pages = {1 -- 10}, year = {2016}, language = {en} } @inproceedings{GrundmannBauerBorchersetal.2019, author = {Grundmann, Jan Thimo and Bauer, Wlademar and Borchers, Kai and Dumont, Etienne and Grimm, Christian D. and Ho, Tra-Mi and Jahnke, Rico and Koch, Aaron D. and Lange, Caroline and Maiwald, Volker and Meß, Jan-Gerd and Mikulz, Eugen and Quantius, Dominik and Reershemius, Siebo and Renger, Thomas and Sasaki, Kaname and Seefeldt, Patric and Spietz, Peter and Spr{\"o}witz, Tom and Sznajder, Maciej and Toth, Norbert and Ceriotti, Matteo and McInnes, Colin and Peloni, Alessandro and Biele, Jens and Krause, Christian and Dachwald, Bernd and Hercik, David and Lichtenheldt, Roy and Wolff, Friederike and Koncz, Alexander and Pelivan, Ivanka and Schmitz, Nicole and Boden, Ralf and Riemann, Johannes and Seboldt, Wolfgang and Wejmo, Elisabet and Ziach, Christian and Mikschl, Tobias and Montenegro, Sergio and Ruffer, Michael and Cordero, Federico and Tardivel, Simon}, title = {Solar sails for planetary defense \& high-energy missions}, series = {IEEE Aerospace Conference Proceedings}, booktitle = {IEEE Aerospace Conference Proceedings}, doi = {10.1109/AERO.2019.8741900}, pages = {1 -- 21}, year = {2019}, abstract = {20 years after the successful ground deployment test of a (20 m) 2 solar sail at DLR Cologne, and in the light of the upcoming U.S. NEAscout mission, we provide an overview of the progress made since in our mission and hardware design studies as well as the hardware built in the course of our solar sail technology development. We outline the most likely and most efficient routes to develop solar sails for useful missions in science and applications, based on our developed `now-term' and near-term hardware as well as the many practical and managerial lessons learned from the DLR-ESTEC Gossamer Roadmap. Mission types directly applicable to planetary defense include single and Multiple NEA Rendezvous ((M)NR) for precursor, monitoring and follow-up scenarios as well as sail-propelled head-on retrograde kinetic impactors (RKI) for mitigation. Other mission types such as the Displaced L1 (DL1) space weather advance warning and monitoring or Solar Polar Orbiter (SPO) types demonstrate the capability of near-term solar sails to achieve asteroid rendezvous in any kind of orbit, from Earth-coorbital to extremely inclined and even retrograde orbits. Some of these mission types such as SPO, (M)NR and RKI include separable payloads. For one-way access to the asteroid surface, nanolanders like MASCOT are an ideal match for solar sails in micro-spacecraft format, i.e. in launch configurations compatible with ESPA and ASAP secondary payload platforms. Larger landers similar to the JAXA-DLR study of a Jupiter Trojan asteroid lander for the OKEANOS mission can shuttle from the sail to the asteroids visited and enable multiple NEA sample-return missions. The high impact velocities and re-try capability achieved by the RKI mission type on a final orbit identical to the target asteroid's but retrograde to its motion enables small spacecraft size impactors to carry sufficient kinetic energy for deflection.}, language = {en} } @article{SchildtBraunMarzocca2019, author = {Schildt, Ph. and Braun, Carsten and Marzocca, P.}, title = {Metric evaluating potentials of condition-monitoring approaches for hybrid electric aircraft propulsion systems}, series = {CEAS Aeronautical Journal}, journal = {CEAS Aeronautical Journal}, publisher = {Springer}, address = {Berlin}, issn = {1869-5590}, doi = {10.1007/s13272-019-00411-3}, pages = {1 -- 14}, year = {2019}, language = {en} } @article{GoettenHavermannBraunetal.2019, author = {G{\"o}tten, Falk and Havermann, Marc and Braun, Carsten and Gomez, Francisco and Bil, Cees}, title = {RANS Simulation Validation of a Small Sensor Turret for UAVs}, series = {Journal of Aerospace Engineering}, volume = {32}, journal = {Journal of Aerospace Engineering}, number = {5}, publisher = {ASCE}, address = {New York}, issn = {1943-5525}, doi = {10.1061/(ASCE)AS.1943-5525.0001055}, pages = {Article number 04019060}, year = {2019}, abstract = {Recent Unmanned Aerial Vehicle (UAV) design procedures rely on full aircraft steady-state Reynolds-Averaged-Navier-Stokes (RANS) analyses in early design stages. Small sensor turrets are included in such simulations, even though their aerodynamic properties show highly unsteady behavior. Very little is known about the effects of this approach on the simulation outcomes of small turrets. Therefore, the flow around a model turret at a Reynolds number of 47,400 is simulated with a steady-state RANS approach and compared to experimental data. Lift, drag, and surface pressure show good agreement with the experiment. The RANS model predicts the separation location too far downstream and shows a larger recirculation region aft of the body. Both characteristic arch and horseshoe vortex structures are visualized and qualitatively match the ones found by the experiment. The Reynolds number dependence of the drag coefficient follows the trend of a sphere within a distinct range. The outcomes indicate that a steady-state RANS model of a small sensor turret is able to give results that are useful for UAV engineering purposes but might not be suited for detailed insight into flow properties.}, language = {en} } @article{WeberEnglhardArentetal.2019, author = {Weber, Tobias and Englhard, Markus and Arent, Jan-Christoph and Hausmann, Joachim}, title = {An experimental characterization of wrinkling generated during prepreg autoclave manufacturing using caul plates}, series = {Journal of Composite Materials}, volume = {53}, journal = {Journal of Composite Materials}, number = {26-27}, issn = {1530-793X}, doi = {10.1177/0021998319846556}, pages = {3757 -- 3773}, year = {2019}, language = {en} } @phdthesis{Weber2019, author = {Weber, Tobias}, title = {Herstellprozesssimulation zur Vorhersage der Faltenbildung in der Prepreg-Autoklav-Fertigung}, publisher = {Technische Universit{\"a}t Kaiserslautern}, address = {Kaiserslautern}, isbn = {978-3-944440-24-8}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:386-kluedo-54923}, pages = {XIV, 207 Seiten}, year = {2019}, language = {de} } @article{OttenWeberArent2018, author = {Otten, Dennis and Weber, Tobias and Arent, Jan-Christoph}, title = {Manufacturing Process Simulation - On Its Way to Industrial Application}, series = {International Journal of Aviation, Aeronautics, and Aerospace}, volume = {5}, journal = {International Journal of Aviation, Aeronautics, and Aerospace}, number = {2}, publisher = {Embry-Riddle Aeronautical University}, address = {Daytona Beach, Fla.}, issn = {2374-6793}, doi = {10.15394/ijaaa.2018.1217}, year = {2018}, abstract = {Manufacturing process simulation (MPS) has become more and more important for aviation and the automobile industry. A highly competitive market requires the use of high performance metals and composite materials in combination with reduced manufacturing cost and time as well as a minimization of the time to market for a new product. However, the use of such materials is expensive and requires sophisticated manufacturing processes. An experience based process and tooling design followed by a lengthy trial-and-error optimization is just not contemporary anymore. Instead, a tooling design process aided by simulation is used more often. This paper provides an overview of the capabilities of MPS in the fields of sheet metal forming and prepreg autoclave manufacturing of composite parts summarizing the resulting benefits for tooling design and manufacturing engineering. The simulation technology is explained briefly in order to show several simplification and optimization techniques for developing industrialized simulation approaches. Small case studies provide examples of an efficient application on an industrial scale.}, language = {en} } @article{WeberRuffStahl2017, author = {Weber, Tobias and Ruff-Stahl, Hans-Joachim K.}, title = {Advances in Composite Manufacturing of Helicopter Parts}, series = {International Journal of Aviation, Aeronautics, and Aerospace}, volume = {4}, journal = {International Journal of Aviation, Aeronautics, and Aerospace}, number = {1}, issn = {2374-6793}, doi = {10.15394/ijaaa.2017.1153}, year = {2017}, language = {en} } @article{WeberArentSteffenetal.2017, author = {Weber, Tobias and Arent, Jan-Christoph and Steffen, Lucas and Balvers, Johannes M. and Duhovic, Miro}, title = {Thermal optimization of composite autoclave molds using the shift factor approach for boundary condition estimation}, series = {Journal of Composite Materials}, volume = {51}, journal = {Journal of Composite Materials}, number = {12}, publisher = {Sage}, address = {London}, issn = {1530-793X}, doi = {10.1177/0021998317699868}, pages = {1753 -- 1767}, year = {2017}, language = {en} } @inproceedings{OttenSchmidtWeber2016, author = {Otten, D. and Schmidt, M. and Weber, Tobias}, title = {Advances in Determination of Material Parameters for Functional Simulations Based on Process Simulations}, series = {SAMPE Europe Conference 16 Liege}, booktitle = {SAMPE Europe Conference 16 Liege}, isbn = {978-1-5108-3800-0}, pages = {570 -- 577}, year = {2016}, language = {en} } @inproceedings{WeberTellisDuhovic2016, author = {Weber, Tobias and Tellis, Jane J. and Duhovic, Miro}, title = {Characterization of tool-part-interaction an interlaminar friction for manufacturing process simulation}, series = {ECCM 17, 17th European Conference on Composite Materials, M{\"u}nchen, DE, Jun 26-30, 2016}, booktitle = {ECCM 17, 17th European Conference on Composite Materials, M{\"u}nchen, DE, Jun 26-30, 2016}, isbn = {978-3-00-053387-7}, pages = {1 -- 7}, year = {2016}, language = {en} } @article{WeberArentMuenchetal.2016, author = {Weber, Tobias and Arent, Jan-Christoph and M{\"u}nch, Lukas and Duhovic, Miro and Balvers, Johannes M.}, title = {A fast method for the generation of boundary conditions for thermal autoclave simulation}, series = {Composites Part A}, volume = {88}, journal = {Composites Part A}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1359-835X}, doi = {10.1016/j.compositesa.2016.05.036}, pages = {216 -- 225}, year = {2016}, abstract = {Manufacturing process simulation enables the evaluation and improvement of autoclave mold concepts early in the design phase. To achieve a high part quality at low cycle times, the thermal behavior of the autoclave mold can be investigated by means of simulations. Most challenging for such a simulation is the generation of necessary boundary conditions. Heat-up and temperature distribution in an autoclave mold are governed by flow phenomena, tooling material and shape, position within the autoclave, and the chosen autoclave cycle. This paper identifies and summarizes the most important factors influencing mold heat-up and how they can be introduced into a thermal simulation. Thermal measurements are used to quantify the impact of the various parameters. Finally, the gained knowledge is applied to develop a semi-empirical approach for boundary condition estimation that enables a simple and fast thermal simulation of the autoclave curing process with reasonably high accuracy for tooling optimization.}, language = {en} } @inproceedings{HailerWeberArent2019, author = {Hailer, Benjamin and Weber, Tobias and Arent, Jan-Christoph}, title = {Manufacturing Process Simulation for Autoclave-Produced Sandwich Structures}, series = {Proceedings of SAMPE Europe Conference 2019, Nantes, France}, booktitle = {Proceedings of SAMPE Europe Conference 2019, Nantes, France}, pages = {1 -- 8}, year = {2019}, language = {en} } @inproceedings{WeberEnglhardHaileretal.2019, author = {Weber, Tobias and Englhard, Markus and Hailer, Benjamin and Arent, Jan-Christoph}, title = {Manufacturing Process Simulation for the Prediction of Tool-Part-Interaction and Ply Wrinkling}, series = {Proceedings of SAMPE Europe Conference 2019, Nantes, France}, booktitle = {Proceedings of SAMPE Europe Conference 2019, Nantes, France}, pages = {1 -- 10}, year = {2019}, language = {en} } @inproceedings{WeberEnglhardHaileretal.2015, author = {Weber, Tobias and Englhard, Markus and Hailer, Benjamin and Arent, Jan-Christoph}, title = {Manufacturing Process Simulation for the Prediction of Tool-Part-Interaction and Ply Wrinkling}, series = {Proceedings of SAMPE Europe Conference, Amiens , France}, booktitle = {Proceedings of SAMPE Europe Conference, Amiens , France}, pages = {1 -- 10}, year = {2015}, language = {en} } @inproceedings{Weber2015, author = {Weber, Tobias}, title = {Manufacturing Process Simulation for Tooling Optimization: Reduction of Quality Issues During Autoclave Manufacturing of Composite Parts}, series = {Proceedings of SAMPE Europe Conference 2015, Amiens, France}, booktitle = {Proceedings of SAMPE Europe Conference 2015, Amiens, France}, pages = {1 -- 8}, year = {2015}, language = {en} } @inproceedings{OttenSchmidWeber2015, author = {Otten, D. and Schmid, M. and Weber, Tobias}, title = {Advances In Sheet Metal-Forming: Reduction Of Tooling Cost By Methodical Optimization}, series = {Proceedings of SAMPE Europe Conference, Amiens , France}, booktitle = {Proceedings of SAMPE Europe Conference, Amiens , France}, year = {2015}, language = {en} } @article{HoevelerBauknechtWolfetal.2020, author = {Hoeveler, B. and Bauknecht, Andr{\´e} and Wolf, C. Christian and Janser, Frank}, title = {Wind-Tunnel Study of a Wing-Embedded Lifting Fan Remaining Open in Cruise Flight}, series = {Journal of Aircraft}, volume = {57}, journal = {Journal of Aircraft}, number = {4}, publisher = {AIAA}, address = {Reston, Va.}, issn = {1533-3868}, doi = {10.2514/1.C035422}, year = {2020}, abstract = {It is investigated whether a nonrotating lifting fan remaining uncovered during cruise flight, as opposed to being covered by a shutter system, can be realized with limited additional drag and loss of lift during cruise flight. A wind-tunnel study of a wing-embedded lifting fan has been conducted at the Side Wind Test Facility G{\"o}ttingen of DLR, German Aerospace Center in G{\"o}ttingen using force, pressure, and stereoscopic particle image velocimetry techniques. The study showed that a step on the lower side of the wing in front of the lifting fan duct increases the lift-to-drag ratio of the whole model by up to 25\% for all positive angles of attack. Different sizes and inclinations of the step had limited influence on the surface pressure distribution. The data indicate that these parameters can be optimized to maximize the lift-to-drag ratio. A doubling of the curvature radius of the lifting fan duct inlet lip on the upper side of the wing affected the lift-to-drag ratio by less than 1\%. The lifting fan duct inlet curvature can therefore be optimized to maximize the vertical fan thrust of the rotating lifting fan during hovering without affecting the cruise flight performance with a nonrotating fan.}, language = {en} } @article{GoettenHavermannBraunetal.2020, author = {G{\"o}tten, Falk and Havermann, Marc and Braun, Carsten and Marino, Matthew and Bil, Cees}, title = {Airfoil drag at low-to-medium reynolds numbers: A novel estimation method}, series = {AIAA Journal}, volume = {58}, journal = {AIAA Journal}, number = {7}, publisher = {AIAA}, address = {Reston, Va.}, issn = {1533-385X}, doi = {10.2514/1.J058983}, pages = {2791 -- 2805}, year = {2020}, abstract = {This paper presents a novel method for airfoil drag estimation at Reynolds numbers between 4×10⁵ and 4×10⁶. The novel method is based on a systematic study of 40 airfoils applying over 600 numerical simulations and considering natural transition. The influence of the airfoil thickness-to-chord ratio, camber, and freestream Reynolds number on both friction and pressure drag is analyzed in detail. Natural transition significantly affects drag characteristics and leads to distinct drag minima for different Reynolds numbers and thickness-to-chord ratios. The results of the systematic study are used to develop empirical correlations that can accurately predict an airfoil drag at low-lift conditions. The new approach estimates a transition location based on airfoil thickness-to-chord ratio, camber, and Reynolds number. It uses the transition location in a mixed laminar-turbulent skin-friction calculation, and corrects the skin-friction coefficient for separation effects. Pressure drag is estimated separately based on correlations of thickness-to-chord ratio, camber, and Reynolds number. The novel method shows excellent accuracy when compared with wind-tunnel measurements of multiple airfoils. It is easily integrable into existing aircraft design environments and is highly beneficial in the conceptual design stage.}, language = {en} } @article{KhayyamJamaliBabHadiasharetal.2020, author = {Khayyam, Hamid and Jamali, Ali and Bab-Hadiashar, Alireza and Esch, Thomas and Ramakrishna, Seeram and Jalili, Mahdi and Naebe, Minoo}, title = {A Novel Hybrid Machine Learning Algorithm for Limited and Big Data Modeling with Application in Industry 4.0}, series = {IEEE Access}, volume = {8}, journal = {IEEE Access}, number = {Art. 9108222}, publisher = {IEEE}, address = {New York, NY}, issn = {2169-3536}, doi = {10.1109/ACCESS.2020.2999898}, pages = {111381 -- 111393}, year = {2020}, abstract = {To meet the challenges of manufacturing smart products, the manufacturing plants have been radically changed to become smart factories underpinned by industry 4.0 technologies. The transformation is assisted by employment of machine learning techniques that can deal with modeling both big or limited data. This manuscript reviews these concepts and present a case study that demonstrates the use of a novel intelligent hybrid algorithms for Industry 4.0 applications with limited data. In particular, an intelligent algorithm is proposed for robust data modeling of nonlinear systems based on input-output data. In our approach, a novel hybrid data-driven combining the Group-Method of Data-Handling and Singular-Value Decomposition is adapted to find an offline deterministic model combined with Pareto multi-objective optimization to overcome the overfitting issue. An Unscented-Kalman-Filter is also incorporated to update the coefficient of the deterministic model and increase its robustness against data uncertainties. The effectiveness of the proposed method is examined on a set of real industrial measurements.}, language = {en} } @article{MaurischatPerkins2020, author = {Maurischat, Andreas and Perkins, Rudolph}, title = {Taylor coefficients of Anderson generating functions and Drinfeld torsion extensions}, number = {Vol. 18, No. 01}, publisher = {World Scientific}, address = {Singapur}, doi = {10.1142/S1793042122500099}, pages = {113 -- 130}, year = {2020}, abstract = {We generalize our work on Carlitz prime power torsion extension to torsion extensions of Drinfeld modules of arbitrary rank. As in the Carlitz case, we give a description of these extensions in terms of evaluations of Anderson generating functions and their hyperderivatives at roots of unity. We also give a direct proof that the image of the Galois representation attached to the p-adic Tate module lies in the p-adic points of the motivic Galois group. This is a generalization of the corresponding result of Chang and Papanikolas for the t-adic case.}, language = {en} } @article{HeinEubanksHibberdetal.2020, author = {Hein, Andreas M. and Eubanks, T. Marshall and Hibberd, Adam and Fries, Dan and Schneider, Jean and Lingam, Manasvi and Kennedy, Robert and Perakis, Nikolaos and Dachwald, Bernd and Kervella, Pierre}, title = {Interstellar Now! Missions to and sample returns from nearby interstellar objects}, publisher = {Elsevier}, address = {Amsterdam}, pages = {1 -- 8}, year = {2020}, abstract = {The recently discovered first high velocity hyperbolic objects passing through the Solar System, 1I/'Oumuamua and 2I/Borisov, have raised the question about near term missions to Interstellar Objects. In situ spacecraft exploration of these objects will allow the direct determination of both their structure and their chemical and isotopic composition, enabling an entirely new way of studying small bodies from outside our solar system. In this paper, we map various Interstellar Object classes to mission types, demonstrating that missions to a range of Interstellar Object classes are feasible, using existing or near-term technology. We describe flyby, rendezvous and sample return missions to interstellar objects, showing various ways to explore these bodies characterizing their surface, dynamics, structure and composition. Interstellar objects likely formed very far from the solar system in both time and space; their direct exploration will constrain their formation and history, situating them within the dynamical and chemical evolution of the Galaxy. These mission types also provide the opportunity to explore solar system bodies and perform measurements in the far outer solar system.}, language = {en} } @article{SeefeldtDachwald2021, author = {Seefeldt, Patric and Dachwald, Bernd}, title = {Temperature increase on folded solar sail membranes}, series = {Advances in Space Research}, volume = {67}, journal = {Advances in Space Research}, number = {9}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0273-1177}, doi = {10.1016/j.asr.2020.09.026}, pages = {2688 -- 2695}, year = {2021}, language = {en} } @inproceedings{GrundmannBieleDachwaldetal.2017, author = {Grundmann, Jan Thimo and Biele, Jens and Dachwald, Bernd and Grimm, Christian D. and Lange, Caroline and Ulamec, Stephan and Ziach, Christian and Spr{\"o}witz, Tom and Ruffer, Michael and Seefeldt, Patric and Spietz, Peter and Toth, Norbert and Mimasu, Yuya and Rittweger, Andreas and Bibring, Jean-Pierre and Braukhane, Andy and Boden, Ralf Christian and Dumont, Etienne and Jahnke, Stephan Siegfried and Jetzschmann, Michael and Kr{\"u}ger, Hans and Lange, Michael and Gomez, Antonio Martelo and Massonett, Didier and Okada, Tatsuaki and Sagliano, Marco and Sasaki, Kaname and Schr{\"o}der, Silvio and Sippel, Martin and Skoczylas, Thomas and Wejmo, Elisabet}, title = {Small landers and separable sub-spacecraft for near-term solar sails}, series = {The Fourth International Symposium on Solar Sailing 2017}, booktitle = {The Fourth International Symposium on Solar Sailing 2017}, pages = {1 -- 10}, year = {2017}, abstract = {Following the successful PHILAE landing with ESA's ROSETTA probe and the launch of the MINERVA rovers and the Mobile Asteroid Surface Scout, MASCOT, aboard the JAXA space probe, HAYABUSA2, to asteroid (162173) Ryugu, small landers have found increasing interest. Integrated at the instrument level in their mothership they support small solar system body studies. With efficient capabilities, resource-friendly design and inherent robustness they are an attractive exploration mission element. We discuss advantages and constraints of small sub-spacecraft, focusing on emerging areas of activity such as asteroid diversity studies, planetary defence, and asteroid mining, on the background of our projects PHILAE, MASCOT, MASCOT2, the JAXA-DLR Solar Power Sail Lander Design Study, and others. The GOSSAMER-1 solar sail deployment concept also involves independent separable sub-spacecraft operating synchronized to deploy the sail. Small spacecraft require big changes in the way we do things and occasionally a little more effort than would be anticipated based on a traditional large spacecraft approach. In a Constraints-Driven Engineering environment we apply Concurrent Design and Engineering (CD/CE), Concurrent Assembly, Integration and Verification (CAIV) and Model-Based Systems Engineering (MBSE). Near-term solar sails will likely be small spacecraft which we expect to harmonize well with nano-scale separable instrument payload packages.}, language = {en} } @inproceedings{SpurmannOhndorfDachwaldetal.2009, author = {Spurmann, J{\"o}rn and Ohndorf, Andreas and Dachwald, Bernd and Seboldt, Wolfgang and L{\"o}b, Horst and Schartner, Karl-Heinz}, title = {Interplanetary trajectory optimization for a sep mission to Saturn}, series = {60th International Astronautical Congress 2009}, booktitle = {60th International Astronautical Congress 2009}, isbn = {9781615679089}, pages = {5234 -- 5248}, year = {2009}, abstract = {The recently proposed NASA and ESA missions to Saturn and Jupiter pose difficult tasks to mission designers because chemical propulsion scenarios are not capable of transferring heavy spacecraft into the outer solar system without the use of gravity assists. Thus our developed mission scenario based on the joint NASA/ESA Titan Saturn System Mission baselines solar electric propulsion to improve mission flexibility and transfer time. For the calculation of near-globally optimal low-thrust trajectories, we have used a method called Evolutionary Neurocontrol, which is implemented in the low-thrust trajectory optimization software InTrance. The studied solar electric propulsion scenario covers trajectory optimization of the interplanetary transfer including variations of the spacecraft's thrust level, the thrust unit's specific impulse and the solar power generator power level. Additionally developed software extensions enabled trajectory optimization with launcher-provided hyperbolic excess energy, a complex solar power generator model and a variable specific impulse ion engine model. For the investigated mission scenario, Evolutionary Neurocontrol yields good optimization results, which also hold valid for the more elaborate spacecraft models. Compared to Cassini/Huygens, the best found solutions have faster transfer times and a higher mission flexibility in general.}, language = {en} } @inproceedings{LoebSchartnerDachwaldetal.2007, author = {Loeb, Horst Wolfgang and Schartner, Karl-Heinz and Dachwald, Bernd and Seboldt, Wolfgang}, title = {SEP-Sample return from a main belt asteroid}, series = {30th International Electric Propulsion Conference}, booktitle = {30th International Electric Propulsion Conference}, pages = {1 -- 11}, year = {2007}, abstract = {By DLR-contact, sample return missions to the large main-belt asteroid "19, Fortuna" have been studied. The mission scenario has been based on three ion thrusters of the RIT-22 model, which is presently under space qualification, and on solar arrays equipped with triple-junction GaAs solar cells. After having designed the spacecraft, the orbit-to-orbit trajectories for both, a one-way SEP mission with a chemical sample return and an all-SEP return mission, have been optimized using a combination of artificial neural networks with evolutionary algorithms. Additionally, body-to-body trajectories have been investigated within a launch period between 2012 and 2015. For orbit-to-orbit calculation, the launch masses of the hybrid mission and of the all-SEP mission resulted in 2.05 tons and 1.56 tons, respectively, including a scientific payload of 246 kg. For the related transfer durations 4.14 yrs and 4.62 yrs were obtained. Finally, a comparison between the mission scenarios based on SEP and on NEP have been carried out favouring clearly SEP.}, language = {en} } @inproceedings{DachwaldMengaliQuartaetal.2007, author = {Dachwald, Bernd and Mengali, Giovanni and Quarta, Alessandro A and Macdonald, Malcolm and McInnes, Colin R}, title = {Optical solar sail degradation modelling}, series = {1st International Symposium on Solar Sailing}, booktitle = {1st International Symposium on Solar Sailing}, pages = {1 -- 27}, year = {2007}, abstract = {We propose a simple parametric OSSD model that describes the variation of the sail film's optical coefficients with time, depending on the sail film's environmental history, i.e., the radiation dose. The primary intention of our model is not to describe the exact behavior of specific film-coating combinations in the real space environment, but to provide a more general parametric framework for describing the general optical degradation behavior of solar sails.}, 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} } @inproceedings{SchoutetensDachwaldHeiligers2021, author = {Schoutetens, Frederic and Dachwald, Bernd and Heiligers, Jeannette}, title = {Optimisation of photon-sail trajectories in the alpha-centauri system using evolutionary neurocontrol}, series = {8th ICATT 2021}, booktitle = {8th ICATT 2021}, pages = {1 -- 15}, year = {2021}, abstract = {With the increased interest for interstellar exploration after the discovery of exoplanets and the proposal by Breakthrough Starshot, this paper investigates the optimisation of photon-sail trajectories in Alpha Centauri. The prime objective is to find the optimal steering strategy for a photonic sail to get captured around one of the stars after a minimum-time transfer from Earth. By extending the idea of the Breakthrough Starshot project with a deceleration phase upon arrival, the mission's scientific yield will be increased. As a secondary objective, transfer trajectories between the stars and orbit-raising manoeuvres to explore the habitable zones of the stars are investigated. All trajectories are optimised for minimum time of flight using the trajectory optimisation software InTrance. Depending on the sail technology, interstellar travel times of 77.6-18,790 years can be achieved, which presents an average improvement of 30\% with respect to previous work. Still, significant technological development is required to reach and be captured in the Alpha-Centauri system in less than a century. Therefore, a fly-through mission arguably remains the only option for a first exploratory mission to Alpha Centauri, but the enticing results obtained in this work provide perspective for future long-residence missions to our closest neighbouring star system.}, language = {en} } @inproceedings{SeefeldtBauerDachwaldetal.2015, author = {Seefeldt, Patric and Bauer, Waldemar and Dachwald, Bernd and Grundmann, Jan Thimo and Straubel, Marco and Sznajder, Maciej and T{\´o}th, Norbert and Zander, Martin E.}, title = {Large lightweight deployable structures for planetary defence: solar sail propulsion, solar concentrator payloads, large-scale photovoltaic power}, series = {4th IAA Planetary Defense Conference - PDC 2015, 13-17 April 2015, Frascati, Roma, Italy}, booktitle = {4th IAA Planetary Defense Conference - PDC 2015, 13-17 April 2015, Frascati, Roma, Italy}, pages = {24}, year = {2015}, language = {en} } @inproceedings{Dachwald2017, author = {Dachwald, Bernd}, title = {Radiation pressure force model for an ideal laser-enhanced solar sail}, series = {4th International Symposium on Solar Sailing}, booktitle = {4th International Symposium on Solar Sailing}, pages = {1 -- 5}, year = {2017}, abstract = {The concept of a laser-enhanced solar sail is introduced and the radiation pressure force model for an ideal laser-enhanced solar sail is derived. A laser-enhanced solar sail is a "traditional" solar sail that is, however, not solely propelled by solar radiation, but additionally by a laser beam that illuminates the sail. The additional laser radiation pressure increases the sail's propulsive force and can give, depending on the location of the laser source, more control authority over the direction of the solar sail's propulsive force vector. This way, laser-enhanced solar sails may augment already existing solar sail mission concepts and make novel mission concepts feasible.}, language = {en} } @inproceedings{DachwaldKahleWie2007, author = {Dachwald, Bernd and Kahle, Ralph and Wie, Bong}, title = {Head-on impact deflection of NEAs: a case study for 99942 Apophis}, series = {Planetary Defense Conference 2007}, booktitle = {Planetary Defense Conference 2007}, pages = {1 -- 12}, year = {2007}, abstract = {Near-Earth asteroid (NEA) 99942 Apophis provides a typical example for the evolution of asteroid orbits that lead to Earth-impacts after a close Earth-encounter that results in a resonant return. Apophis will have a close Earth-encounter in 2029 with potential very close subsequent Earth-encounters (or even an impact) in 2036 or later, depending on whether it passes through one of several less than 1 km-sized gravitational keyholes during its 2029-encounter. A pre-2029 kinetic impact is a very favorable option to nudge the asteroid out of a keyhole. The highest impact velocity and thus deflection can be achieved from a trajectory that is retrograde to Apophis orbit. With a chemical or electric propulsion system, however, many gravity assists and thus a long time is required to achieve this. We show in this paper that the solar sail might be the better propulsion system for such a mission: a solar sail Kinetic Energy Impactor (KEI) spacecraft could impact Apophis from a retrograde trajectory with a very high relative velocity (75-80 km/s) during one of its perihelion passages. The spacecraft consists of a 160 m × 160 m, 168 kg solar sail assembly and a 150 kg impactor. Although conventional spacecraft can also achieve the required minimum deflection of 1 km for this approx. 320 m-sized object from a prograde trajectory, our solar sail KEI concept also allows the deflection of larger objects. For a launch in 2020, we also show that, even after Apophis has flown through one of the gravitational keyholes in 2029, the solar sail KEI concept is still feasible to prevent Apophis from impacting the Earth, but many KEIs would be required for consecutive impacts to increase the total Earth-miss distance to a safe value}, language = {en} } @inproceedings{GrundmannBodenCeriottietal.2017, author = {Grundmann, Jan Thimo and Boden, Ralf and Ceriotti, Matteo and Dachwald, Bernd and Dumont, Etienne and Grimm, Christian D. and Lange, Caroline and Lichtenheldt, Roy and Pelivan, Ivanka and Peloni, Alessandro and Riemann, Johannes and Spr{\"o}witz, Tom and Tardivel, Simon}, title = {Soil to sail-asteroid landers on near-term sailcraft as an evolution of the GOSSAMER small spacecraft solar sail concept for in-situ characterization}, series = {5th IAA Planetary Defense Conference}, booktitle = {5th IAA Planetary Defense Conference}, pages = {30 Seiten}, year = {2017}, language = {en} } @incollection{Dachwald2010, author = {Dachwald, Bernd}, title = {Solar sail dynamics and control}, series = {Encyclopedia of Aerospace Engineering}, booktitle = {Encyclopedia of Aerospace Engineering}, publisher = {Wiley}, address = {Hoboken}, doi = {10.1002/9780470686652.eae292}, year = {2010}, abstract = {Solar sails are large and lightweight reflective structures that are propelled by solar radiation pressure. This chapter covers their orbital and attitude dynamics and control. First, the advantages and limitations of solar sails are discussed and their history and development status is outlined. Because the dynamics of solar sails is governed by the (thermo-)optical properties of the sail film, the basic solar radiation pressure force models have to be described and compared before parameters to measure solar sail performance can be defined. The next part covers the orbital dynamics of solar sails for heliocentric motion, planetocentric motion, and motion at Lagrangian equilibrium points. Afterwards, some advanced solar radiation pressure force models are described, which allow to quantify the thrust force on solar sails of arbitrary shape, the effects of temperature, of light incidence angle, of surface roughness, and the effects of optical degradation of the sail film in the space environment. The orbital motion of a solar sail is strongly coupled to its rotational motion, so that the attitude control of these soft and flexible structures is very challenging, especially for planetocentric orbits that require fast attitude maneuvers. Finally, some potential attitude control methods are sketched and selection criteria are given.}, language = {en} } @inproceedings{SeboldtDachwald2003, author = {Seboldt, Wolfgang and Dachwald, Bernd}, title = {Solar sails for near-term advanced scientific deep space missions}, series = {Proceedings of the 8th International Workshop on Combustion and Propulsion}, booktitle = {Proceedings of the 8th International Workshop on Combustion and Propulsion}, pages = {14 Seiten}, year = {2003}, abstract = {Solar sails are propelled in space by reflecting solar photons off large mirroring surfaces, thereby transforming the momentum of the photons into a propulsive force. This innovative concept for low-thrust space propulsion works without any propellant and thus provides a wide range of opportunities for highenergy low-cost missions. Offering an efficient way of propulsion, solar sailcraft could close a gap in transportation options for highly demanding exploration missions within our solar system and even beyond. On December 17th, 1999, a significant step was made towards the realization of this technology: a lightweight solar sail structure with an area of 20 m × 20 m was successfully deployed on ground in a large facility at the German Aerospace Center (DLR) at Cologne. The deployment from a package of 60 cm × 60 cm × 65 cm with a total mass of less than 35 kg was achieved using four extremely light-weight carbon fiber reinforced plastics (CFRP) booms with a specific mass of 100 g/m. The paper briefly reviews the basic principles of solar sails as well as the technical concept and its realization in the ground demonstration experiment, performed in close cooperation between DLR and ESA. Next possible steps are outlined. They could comprise the in-orbit demonstration of the sail deployment on the upper stage of a low-cost rocket and the verification of the propulsion concept by an autonomous and free flying solar sail in the frame of a scientific mission. It is expected that the present design could be extended to sail sizes of about (40 m)2 up to even (70 m)2 without significant mass penalty. With these areas, the maximum achievable thrust at 1 AU would range between 10 and 40 mN - comparable to some electric thrusters. Such prototype sails with a mass between 50 and 150 kg plus a micro-spacecraft of 50 to 250 kg would have a maximum acceleration in the order of 0.1 mm/s2 at 1 AU, corresponding to a maximum ∆V-capability of about 3 km/s per year. Two near/medium-term mission examples to a near-Earth asteroid (NEA) will be discussed: a rendezvous mission and a sample return mission.}, language = {en} } @inproceedings{DachwaldSeboldtHaeusler2002, author = {Dachwald, Bernd and Seboldt, Wolfgang and H{\"a}usler, Bernd}, title = {Performance requirements for near-term interplanetary solar sailcraft missions}, series = {6th International AAAF Symposium on Space Propulsion: Propulsion for Space Transportation of the XXIst Century}, booktitle = {6th International AAAF Symposium on Space Propulsion: Propulsion for Space Transportation of the XXIst Century}, pages = {9 Seiten}, year = {2002}, abstract = {Solar sailcraft provide a wide range of opportunities for high-energy low-cost missions. To date, most mission studies require a rather demanding performance that will not be realized by solar sailcraft of the first generation. However, even with solar sailcraft of moderate performance, scientifically relevant missions are feasible. This is demonstrated with a Near Earth Asteroid sample return mission and various planetary rendezvous missions.}, language = {en} } @article{LoebSchartnerDachwaldetal.2012, author = {Loeb, Horst Wolfgang and Schartner, Karl-Heinz and Dachwald, Bernd and Ohndorf, Andreas and Seboldt, Wolfgang}, title = {Interstellar heliopause probe}, series = {Труды МАИ}, journal = {Труды МАИ}, number = {60}, publisher = {Moskauer Staatliches Luftfahrtinstitut (МАИ)}, address = {Moskau}, pages = {2 -- 2}, year = {2012}, abstract = {There is common agreement within the scientific community that in order to understand our local galactic environment it will be necessary to send a spacecraft into the region beyond the solar wind termination shock. Considering distances of 200 AU for a new mission, one needs a spacecraft traveling at a speed of close to 10 AU/yr in order to keep the mission duration in the range of less than 25 yrs, a transfer time postulated by European Space Agency (ESA). Two propulsion options for the mission have been proposed and discussed so far: the solar sail propulsion and the ballistic/radioisotope-electric propulsion (REP). As a further alternative, we here investigate a combination of solar-electric propulsion (SEP) and REP. The SEP stage consists of six 22-cms diameter RIT-22 ion thrusters working with a high specific impulse of 7377 s corresponding to a positive grid voltage of 5 kV. Solar power of 53 kW at begin of mission (BOM) is provided by a lightweight solar array.}, language = {en} } @inproceedings{OhndorfDachwaldSeboldtetal.2011, author = {Ohndorf, Andreas and Dachwald, Bernd and Seboldt, Wolfgang and Schartner, Karl-Heinz}, title = {Flight times to the heliopause using a combination of solar and radioisotope electric propulsion}, series = {32nd International Electric Propulsion Conference}, booktitle = {32nd International Electric Propulsion Conference}, pages = {1 -- 12}, year = {2011}, abstract = {We investigate the interplanetary flight of a low-thrust space probe to the heliopause,located at a distance of about 200 AU from the Sun. Our goal was to reach this distance within the 25 years postulated by ESA for such a mission (which is less ambitious than the 15-year goal set by NASA). Contrary to solar sail concepts and combinations of allistic and electrically propelled flight legs, we have investigated whether the set flight time limit could also be kept with a combination of solar-electric propulsion and a second, RTG-powered upper stage. The used ion engine type was the RIT-22 for the first stage and the RIT-10 for the second stage. Trajectory optimization was carried out with the low-thrust optimization program InTrance, which implements the method of Evolutionary Neurocontrol,using Artificial Neural Networks for spacecraft steering and Evolutionary Algorithms to optimize the Neural Networks' parameter set. Based on a parameter space study, in which the number of thrust units, the unit's specific impulse, and the relative size of the solar power generator were varied, we have chosen one configuration as reference. The transfer time of this reference configuration was 29.6 years and the fastest one, which is technically more challenging, still required 28.3 years. As all flight times of this parameter study were longer than 25 years, we further shortened the transfer time by applying a launcher-provided hyperbolic excess energy up to 49 km2/s2. The resulting minimal flight time for the reference configuration was then 27.8 years. The following, more precise optimization to a launch with the European Ariane 5 ECA rocket reduced the transfer time to 27.5 years. This is the fastest mission design of our study that is flexible enough to allow a launch every year. The inclusion of a fly-by at Jupiter finally resulted in a flight time of 23.8 years,which is below the set transfer-time limit. However, compared to the 27.5-year transfer,this mission design has a significantly reduced launch window and mission flexibility if the escape direction is restricted to the heliosphere's "nose".}, language = {en} }