@article{UlmerBraunChengetal.2022, author = {Ulmer, Jessica and Braun, Sebastian and Cheng, Chi-Tsun and Dowey, Steve and Wollert, J{\"o}rg}, title = {Gamification of virtual reality assembly training: Effects of a combined point and level system on motivation and training results}, series = {International Journal of Human-Computer Studies}, volume = {165}, journal = {International Journal of Human-Computer Studies}, number = {Art. No. 102854}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1071-5819}, doi = {10.1016/j.ijhcs.2022.102854}, year = {2022}, abstract = {Virtual Reality (VR) offers novel possibilities for remote training regardless of the availability of the actual equipment, the presence of specialists, and the training locations. Research shows that training environments that adapt to users' preferences and performance can promote more effective learning. However, the observed results can hardly be traced back to specific adaptive measures but the whole new training approach. This study analyzes the effects of a combined point and leveling VR-based gamification system on assembly training targeting specific training outcomes and users' motivations. The Gamified-VR-Group with 26 subjects received the gamified training, and the Non-Gamified-VR-Group with 27 subjects received the alternative without gamified elements. Both groups conducted their VR training at least three times before assembling the actual structure. The study found that a level system that gradually increases the difficulty and error probability in VR can significantly lower real-world error rates, self-corrections, and support usages. According to our study, a high error occurrence at the highest training level reduced the Gamified-VR-Group's feeling of competence compared to the Non-Gamified-VR-Group, but at the same time also led to lower error probabilities in real-life. It is concluded that a level system with a variable task difficulty should be combined with carefully balanced positive and negative feedback messages. This way, better learning results, and an improved self-evaluation can be achieved while not causing significant impacts on the participants' feeling of competence.}, language = {en} } @inproceedings{WiegnerVolkerMainzetal.2022, author = {Wiegner, Jonas and Volker, Hanno and Mainz, Fabian and Backes, Andreas and L{\"o}ken, Michael and H{\"u}ning, Felix}, title = {Wiegand-effect-powered wireless IoT sensor node}, series = {ITG-Fb. 303: Sensoren und Messsysteme}, booktitle = {ITG-Fb. 303: Sensoren und Messsysteme}, publisher = {VDE Verlag GmbH}, address = {Berlin}, isbn = {978-3-8007-5835-7}, pages = {255 -- 260}, year = {2022}, abstract = {In this article we describe an Internet-of-Things sensing device with a wireless interface which is powered by the oftenoverlooked harvesting method of the Wiegand effect. The sensor can determine position, temperature or other resistively measurable quantities and can transmit the data via an ultra-low power ultra-wideband (UWB) data transmitter. With this approach we can energy-self-sufficiently acquire, process, and wirelessly transmit data in a pulsed operation. A proof-of-concept system was built up to prove the feasibility of the approach. The energy consumption of the system is analyzed and traced back in detail to the individual components, compared to the generated energy and processed to identify further optimization options. Based on the proof-of-concept, an application demonstrator was developed. Finally, we point out possible use cases.}, language = {en} } @masterthesis{Liske2022, type = {Bachelor Thesis}, author = {Liske, Lara}, title = {Nach der Karte : Mappings migrantischer Narrative}, publisher = {FH Aachen}, address = {Aachen}, pages = {67 Seiten}, year = {2022}, abstract = {Durch demographischen Wandel wird der Kontrast zwischen der starr {\"u}ber Grenzziehung definierten Kartographie und der tats{\"a}chlichen Bewegung von Menschen immer st{\"a}rker. In dieser Arbeit wird der vermeintlichen Neutralit{\"a}t einer gew{\"o}hnlichen Karte auf den Zahn gef{\"u}hlt. Denn statt sich auf die geografischen Regeln zu beschr{\"a}nken, versteht sie den Raum als ein komplexes Netzwerk sozialer Beziehungszusammenh{\"a}nge. Sie orientiert sich daf{\"u}r an migrantischen Lebensgeschichten, die zahlreiche Verbindungen zwischen unterschiedliche Orte spannen. Die Dreidimensionalit{\"a}t dieser Konstruktion {\"o}ffnet dazu den Blick f{\"u}r die vielen Dimensionen dieser geografischen Bewegung. Durch den Perspektivwechsel wird der Ansatz hinterfragt, unter dem Kartographie bis jetzt betrachtet wurde. Das Raumkonzept wird weiter-gedacht - {\"u}ber Grenzen hinweg.}, language = {de} } @masterthesis{Hambloch2022, type = {Bachelor Thesis}, author = {Hambloch, Antonia}, title = {Wie ein Stier im Porzellanladen}, publisher = {FH Aachen}, address = {Aachen}, pages = {35 Seiten}, year = {2022}, abstract = {Menschliche Kommunikation ist gepr{\"a}gt von Sprichw{\"o}rtern und Redewendungen. Von Generation zu Generation weitergegeben, spiegeln sie Lebenserfahrungen, Traditionen und Moralvorstellungen wider, die sich im Laufe der Zeit im allgemeinen Sprachgebrauch etabliert haben. Redensarten werden von Menschen auf der ganzen Welt verwendet. H{\"a}ufig stammen diese bildhaften Vergleiche aus dem Tierreich, was auf die lange gemeinsame Vergangenheit von Tier und Mensch zur{\"u}ckzuf{\"u}hren ist. Bis heute spielen Tiere eine besondere Rolle im Alltag vieler Menschen. Die Ausdr{\"u}cke, die in dem Sachbuch „Wie ein Stier im Porzellanladen" illustrativ und textlich veranschaulicht werden, sind Redensarten {\"u}ber Tiere aus verschiedenen Zeiten, Sprachen und L{\"a}ndern. Manche werden Lesenden bekannt vorkommen, andere {\"o}ffnen den Blick f{\"u}r neue Ausdrucksweisen. Sie am{\"u}sieren in ihrer faszinierenden Vielfalt durch erfrischenden Humor. Das Buch offenbart auf unterhaltsame Weise, wie {\"a}hnlich die Gedanken der Menschen, die sich in spannenden Analogien zwischen Sprachen und Kulturen widerspiegeln, bei n{\"a}herer Betrachtung eigentlich sind.}, language = {de} } @masterthesis{Frank2022, type = {Bachelor Thesis}, author = {Frank, Jemima Leonie}, title = {Falling in love with the female gaze}, publisher = {FH Aachen}, address = {Aachen}, school = {Fachhochschule Aachen}, pages = {81 Seiten}, year = {2022}, abstract = {Der „Male Gaze" bezeichnet das typische Erleben der Umwelt aus m{\"a}nnlicher Perspektive und pr{\"a}gt in den sogenannten Mainstream-Medien die Gestaltung von Film, Fernsehen und Werbung. Dadurch werden von dargestellten Personen h{\"a}ufig die k{\"o}rperlichen Aspekte hervorgehoben. Im Gegensatz dazu gilt das weibliche Pendant, der „Female Gaze", als besonders emotionsbetont. Weil Medien einen enormen Einfluss auf gesellschaftliches und individuelles Denken haben, stellt die Dominanz des „Male Gaze" eine Unausgeglichenheit dar, die sich in verschiedenen Bereichen des gesellschaftlichen Lebens widerspiegelt. Deswegen m{\"o}chte dieses Projekt die Medien um die weibliche Sichtweise erweitern und damit die dort transportierten Bilder diverser und ausgewogener machen. Die Fotografie fokussiert sich dabei auf die Gef{\"u}hlswelt der Protagonistin, womit die Betrachter:Innen schrittweise in ihre Position hineinversetzt werden sollen. Mit Augen des Mitgef{\"u}hls und eigenem Sch{\"o}nheitsbegriff l{\"a}sst „Falling in love with the female gaze" endlich auch die Frau zu Wort kommen.}, language = {de} } @masterthesis{Ebert2022, type = {Bachelor Thesis}, author = {Ebert, Julia}, title = {Die unsichtbare Gefahr : Mikroplastik}, publisher = {FH Aachen}, address = {Aachen}, school = {Fachhochschule Aachen}, pages = {23 Seiten}, year = {2022}, abstract = {Bereits ein einziger pr{\"u}fender Blick in einen klassischen Privathaushalt vermittelt einen ersten Eindruck davon, wie allgegenw{\"a}rtig Kunststoff im menschlichen Leben ist. H{\"a}ufig {\"u}bersehen wird dabei Mikroplastik, welches im Verh{\"a}ltnis zu seinen gravierenden Auswirkungen auf Mensch und Umwelt in der {\"o}ffentlichen Diskussion bislang noch wenig Beachtung findet. Das f{\"u}hrt dazu, dass die Problematik durch unaufgekl{\"a}rten Konsum weiter angefacht wird. Die Gestaltung des visuellen Magazins m{\"o}chte {\"u}ber die Konsequenzen von Mikroplastik aufkl{\"a}ren und das Bewusstsein {\"u}ber das pers{\"o}nliche Konsumverhalten sch{\"a}rfen. Mithilfe kurzer Infotexte wird die Problematik aus der wissenschaftlichen Perspektive der Umweltorganisationen beleuchtet und durch ausgew{\"a}hlte Mikroskop-Aufnahmen illustriert. Hiermit werden unsichtbare Krisentreiber endlich sichtbar gemacht.}, language = {de} } @masterthesis{Eberhardt2022, type = {Bachelor Thesis}, author = {Eberhardt, Dag Norman}, title = {"I Was Here!"}, publisher = {FH Aachen}, address = {Aachen}, pages = {77 Seiten}, year = {2022}, abstract = {Die Menschheit erlebt aktuell Zeiten drastischen Wandels. Deswegen k{\"o}nnte es wohltun, einen Blick in die Vergangenheit zu werfen und sich darauf zu besinnen, wo die Menschen herkommen, wer sie waren und was seitdem bereits erreicht wurde. In dieser Grafiknovelle wird ein kleiner Steinzeitjunge namens Muami begleitet, der vor 35.000 Jahren die Verg{\"a}nglichkeit des Lebens kennenlernt. Im Verlauf des folgenden Jahres erfindet er die Selbstverewigung in der H{\"o}hlenmalerei. Mit seiner Figur soll aufgezeigt werden, dass die fr{\"u}hen Europ{\"a}er eben keine primitiven Halbaffen, sondern intelligente und außerdem zutiefst kreative Menschen waren. Trotz ihrer rauen Umwelt waren ihre Sorgen und Freuden den unseren gar nicht so un{\"a}hnlich. „I Was Here!" ist ein Versuch, ein authentisches Portr{\"a}t jener Menschen zu schaffen und dabei ihrer Welt, ihrem Leben und ihrer Kunst gerecht zu werden.}, language = {de} } @masterthesis{Dereli2022, type = {Bachelor Thesis}, author = {Dereli, Aziz}, title = {[NON]HUMAN}, publisher = {FH Aachen}, address = {Aachen}, pages = {50 Seiten}, year = {2022}, abstract = {"[NON]HUMAN" ist ein 3D-animierter Kurzfilm, der in einer Zombieapokalypse spielt und sich mit dem Thema der Menschlichkeit befasst. Welche Taten k{\"o}nnen gerechtfertigt werden und welche nicht? Die Handlungsm{\"o}glichkeiten der Menschen im Zuge des Ausbruchs eines neuen Virus werfen viele moralische Fragen auf, mit denen zwischen den Zeilen gerungen wird. Denn in diesem Film bestimmen sie Leben und Tod. Das Ziel dieser Arbeit war es, eine simple Geschichte spannend zu erz{\"a}hlen, indem das Publikum durch eindrucksstarke Bilder gefesselt wird. Dabei er{\"o}ffnen 3D-Animationen neue M{\"o}glichkeiten, die insbesondere in den Aufnahmen der zerst{\"o}rten Stadt zur Geltung kommen. Diese Arbeit zeigt spielerisch, wie sich mit etwas technischem Know-How auch ohne großem Budget hochwertige Filme drehen l{\"a}sst, indem man das Potential smart aussch{\"o}pft.}, language = {de} } @masterthesis{Bauer2022, type = {Bachelor Thesis}, author = {Bauer, Eva}, title = {Music of the Spheres : der Klang der Planeten}, publisher = {FH Aachen}, address = {Aachen}, pages = {59 Seiten}, year = {2022}, abstract = {"Die Bachelorarbeit "Music of the Spheres" soll wissenschaftliche und k{\"u}nstlerische Elemente zum Thema "Klang der Planeten" in Form einer popul{\"a}rwissenschaftlichen Publikation versammeln. Seit Beginn der Menschheit fasziniert uns der Blick in den n{\"a}chtlichen Sternenhimmel. Einher geht die Sehnsucht des Unbekannten, die unsere Fantasie befl{\"u}gelt. Als auf die Erde gebundenen Lebewesens treibt uns der Drang, mehr {\"u}ber das Universum da draußen herauszufinden. Dieses Spannungsfeld zwischen Wissensdrang und Fantasie ist eine interessante Grundlage f{\"u}r die geplante Bachelorarbeit. In der Bachelorarbeit sollen unsere Emotionen mit wissenschaftlichen Erkenntnissen verbunden werden. F{\"u}r das menschliche Ohr ist die Klangwelt des Weltalls, verursacht durch die sich bewegenden Planeten, ohne Hilfsmittel nicht h{\"o}rbar. Nach unseren bekannten physikalischen Erkenntnissen ist es im Weltraum komplett still, aufgrund des im All vorherrschenden Vakuums. Der Schall kann sich nicht wie auf der Erde {\"u}ber Schallwellen ausbreiten. In der Publikation soll der Klang der Planeten beschrieben bzw. dargestellt werden. Die wissenschaftshistorische Dimension soll aufgezeigt werden. So hat man sich zum Beispiel in der Antike musikalische und lyrische Bilder davon gemacht, wie sich der Klang des Weltalls und der Planeten anh{\"o}ren k{\"o}nnte. Weiterhin faszinierte diese Frage K{\"u}nstler unterschiedlicher Epochen und Stilrichtungen, und ist bis heute ein Thema das Anlaß zu k{\"u}nstlerischem Schaffen gibt. In Form einer Printpublikation soll die Bachelorarbeit historische Thesen und aktuelle wissenschaftliche Texte, Forschungsberichte und Klangdokumente zusammenbringen, literarische und musikalische Umsetzungen zum Thema aufzeigen, und mit wissenschaftlichem und k{\"u}nstlerisch-interpretativem Bildmaterial vereinen. Um das Thema visuell zu veranschaulichen, sollen die Texte durch Bilder und Siebdrucke erg{\"a}nzt werden. Selbst erstellte Siebdruck Experimente k{\"o}nnten mit- und ineinander verkn{\"u}pft werden. Die Publikation weißt ein durchgehendes Gestaltungskonzept auf, welches Texte, Illustrationen und Bildmaterial als Einheit verkn{\"u}pfen und wiedererkennbar machen. Ebenfalls ist die Auswahl der verwendeten Materialien und Verarbeitungstechniken, wie Druck, Bindung und Papier zu beachten. Neben dem Text- und Bildmaterial werden Klang-Beispiele eingebunden durch QR Codes. So kann der Leser den QR Code der Siebdrucke scannen, um den von der US-Weltraumorganisation NASA erstellten Klang des Planeten anzuh{\"o}ren. Oder ausgehend von wissenschaftlichem Bildmaterial kann der Leser per Scan eine musikalische Partition zum entsprechenden Planeten anh{\"o}ren. Die angestrebte Zielgruppe besteht aus Wissenschafts- und Designaffinen Personen, die sich insbesondere f{\"u}r den Weltraum interessieren. Entsprechend soll die Gestaltung informativ und gleichzeitig zeitgen{\"o}ssisch sein, um Aufmerksamkeit zu erregen. Mit dem Inhalt der Publikation soll dem Leser gleichzeitig auch der Klang der Planeten h{\"o}rbar zug{\"a}nglich gemacht werden.}, language = {de} } @phdthesis{DahmenBeumers2005, author = {Dahmen-Beumers, Judith}, title = {Eine exemplarische Untersuchung zur Regionalit{\"a}t in der Kunst : der Aachener Bildhauer und Maler Benno Werth (*1929)}, publisher = {Books on Demand}, address = {Norderstedt}, isbn = {3-8334-3014-1}, pages = {IV, 297 Seiten}, year = {2005}, language = {de} } @incollection{DiekmannEggert2021, author = {Diekmann, Julian and Eggert, Mathias}, title = {Is a Progressive Web App an Alternative for Native App Development?}, series = {3. Wissenschaftsforum: Digitale Transformation (WiFo21) (Lecture Notes in Informatics ; P-319)}, booktitle = {3. Wissenschaftsforum: Digitale Transformation (WiFo21) (Lecture Notes in Informatics ; P-319)}, publisher = {Gesellschaft f{\"u}r Informatik}, address = {Darmstadt}, isbn = {978-3-88579-713-5}, pages = {35 -- 48}, year = {2021}, abstract = {The existence of several mobile operating systems, such as Android and iOS, is a challenge for developers because the individual platforms are not compatible with each other and require separate app developments. For this reason, cross-platform approaches have become popular but lack in cloning the native behavior of the different operating systems. Out of the plenty cross-platform approaches, the progressive web app (PWA) approach is perceived as promising but needs further investigation. Therefore, the paper at hand aims at investigating whether PWAs are a suitable alternative for native apps by developing a PWA clone of an existing app. Two surveys are conducted in which potential users test and evaluate the PWA prototype with regard to its usability. The survey results indicate that PWAs have great potential, but cannot be treated as a general alternative to native apps. For guiding developers when and how to use PWAs, four design guidelines for the development of PWA-based apps are derived based on the results.}, 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{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{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} } @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{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} } @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{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{SchartnerLoebDachwaldetal.2009, author = {Schartner, Karl-Heinz and Loeb, H. W. and Dachwald, Bernd and Ohndorf, Andreas}, title = {Perspectives of electric propulsion for outer planetary and deep space missions}, series = {European Planetary Science Congress 2009}, booktitle = {European Planetary Science Congress 2009}, pages = {416 -- 416}, year = {2009}, abstract = {Solar-electric propulsion (SEP) is superior with respect to payload capacity, flight time and flexible launch window to the conventional interplanetary transfer method using chemical propulsion combined with gravity assists. This fact results from the large exhaust velocities of electric low-thrust propulsion and is favourable also for missions to the giant planets, Kuiper-belt objects and even for a heliopause probe (IHP) as shown in three studies by the authors funded by DLR. They dealt with a lander for Europa and a sample return mission from a mainbelt asteroid [1], with the TANDEM mission [2]; the third recent one investigates electric propulsion for the transfer to the edge of the solar system. All studies are based on triple-junction solar arrays, on rf-ion thrusters of the qualified RIT-22 type and they use the intelligent trajectory optimization program InTrance [3].}, language = {en} } @inproceedings{BorggraefeDachwald2010, author = {Borggr{\"a}fe, Andreas and Dachwald, Bernd}, title = {Mission performance evaluation for solar sails using a refined SRP force model with variable optical coefficients}, series = {2nd International Symposium on Solar Sailing}, booktitle = {2nd International Symposium on Solar Sailing}, pages = {1 -- 6}, year = {2010}, abstract = {Solar sails provide ignificant advantages over other low-thrust propulsion systems because they produce thrust by the momentum exchange from solar radiation pressure (SRP) and thus do not consume any propellant.The force exerted on a very thin sail foil basically depends on the light incidence angle. Several analytical SRP force models that describe the SRP force acting on the sail have been established since the 1970s. All the widely used models use constant optical force coefficients of the reflecting sail material. In 2006,MENGALI et al. proposed a refined SRP force model that takes into account the dependancy of the force coefficients on the light incident angle,the sail's distance from the sun (and thus the sail emperature) and the surface roughness of the sail material [1]. In this paper, the refined SRP force model is compared to the previous ones in order to identify the potential impact of the new model on the predicted capabilities of solar sails in performing low-cost interplanetary space missions. All force models have been implemented within InTrance, a global low-thrust trajectory optimization software utilizing evolutionary neurocontrol [2]. Two interplanetary rendezvous missions, to Mercury and the near-Earth asteroid 1996FG3, are investigated. Two solar sail performances in terms of characteristic acceleration are examined for both scenarios, 0.2 mm/s2 and 0.5 mm/s2, termed "low" and "medium" sail performance. In case of the refined SRP model, three different values of surface roughness are chosen, h = 0 nm, 10 nm and 25 nm. The results show that the refined SRP force model yields shorter transfer times than the standard model.}, language = {en} }