TY  - JOUR
A1  - Henn, Gudrun
A1  - Polaczek, Christa
T1  - Studienerfolg in den Ingenieurwissenschaften
JF  - Das Hochschulwesen : HSW ; Forum für Hochschulforschung, -praxis und -politik
Y1  - 2007
SN  - 0018-2974
VL  - 55
IS  - 5
SP  - 144
EP  - 147
ER  - 
TY  - BOOK
A1  - Esch, Thomas
T1  - Experimentelle Untersuchungen an Antriebssystemen von Kraft-, Luft- und Raumfahrzeugen : Vorlesungsumdruck. Bd. 1
Y1  - 2007
PB  - Fachhochschule Aachen, Lehr- und Forschungsgebiet Thermodynamik und Verbrennungstechnik
CY  - Aachen
ER  - 
TY  - BOOK
A1  - Esch, Thomas
T1  - Experimentelle Untersuchungen an Antriebssystemen von Kraft-, Luft- und Raumfahrzeugen : Vorlesungsumdruck. Bd. 2
Y1  - 2007
PB  - Fachhochschule Aachen, Lehr- und Forschungsgebiet Thermodynamik und Verbrennungstechnik
CY  - Aachen
ER  - 
TY  - CHAP
A1  - Dachwald, Bernd
T1  - Low-Thrust Mission Analysis and Global Trajectory Optimization Using Evolutionary Neurocontrol: New Results
T2  - European Workshop on Space Mission Analysis ESA/ESOC, Darmstadt, Germany 10 { 12 Dec 2007
N2  - Interplanetary trajectories for low-thrust spacecraft are often characterized by multiple revolutions around the sun. Unfortunately, the convergence of traditional trajectory optimizers that are based on numerical optimal control methods depends strongly on an adequate initial guess for the control function (if a direct method is used) or for the starting values of the adjoint vector (if an indirect method is used). Especially when many revolutions around the sun are re-
quired, trajectory optimization becomes a very difficult and time-consuming task that involves a lot of experience and expert knowledge in astrodynamics and optimal control theory, because an adequate initial guess is extremely hard to find. Evolutionary neurocontrol (ENC) was proposed as a smart method for low-thrust trajectory optimization that fuses artificial neural networks and evolutionary algorithms to so-called evolutionary neurocontrollers (ENCs) [1]. Inspired by natural archetypes, ENC attacks the trajectoryoptimization problem from the perspective of artificial intelligence and machine learning, a perspective that is quite different from that of optimal control theory. Within the context of ENC, a trajectory is regarded as the result of a spacecraft steering strategy that maps permanently the actual spacecraft state and the actual target state onto the actual spacecraft control vector. This way, the problem of searching the optimal spacecraft trajectory is equivalent to the problem of searching (or "learning") the optimal spacecraft steering strategy. An artificial neural network is used to implement such a spacecraft steering strategy. It can be regarded as a parameterized function (the network function) that is defined by the internal network parameters. Therefore, each distinct set of network parameters defines a different network function and thus a different steering strategy. The problem of searching the optimal steering strategy is now equivalent to the problem of searching the optimal set of network parameters. Evolutionary algorithms that work on a population of (artificial) chromosomes are used to find the optimal network parameters, because the parameters can be easily mapped onto a chromosome. The trajectory optimization problem is solved when the optimal chromosome is found. A comparison of solar sail trajectories that have been published by others [2, 3, 4, 5] with ENC-trajectories has shown that ENCs can be successfully applied for near-globally optimal spacecraft control [1, 6] and that they are able to find trajectories that are closer to the (unknown) global optimum, because they explore the trajectory search space more exhaustively than a human expert can do. The obtained trajectories are fairly accurate with respect to the terminal constraint. If a more accurate trajectory is required, the ENC-solution can be used as an initial guess for a local trajectory optimization method. Using ENC, low-thrust trajectories can be optimized without an initial guess and without expert attendance.
Here, new results for nuclear electric spacecraft and for solar sail spacecraft are presented and it will be shown that ENCs find very good trajectories even for very difficult problems. Trajectory optimization results are presented for 1. NASA's Solar Polar Imager Mission, a mission to attain a highly inclined close solar orbit with a solar sail [7] 2. a mission to de ect asteroid Apophis with a solar sail from a retrograde orbit with a very-high velocity impact [8, 9] 3. JPL's \2nd Global Trajectory Optimization Competition", a grand tour to visit four asteroids from different classes with a NEP spacecraft
Y1  - 2007
ER  - 
TY  - CHAP
A1  - Dachwald, Bernd
A1  - Seboldt, Wolfgang
A1  - Loeb, Horst W.
A1  - Schartner, Karl-Heinz
T1  - A comparison of SEP and NEP for a main belt asteroid sample return mission
T2  - 7th International Symposium on Launcher Technologies, Barcelona, Spain, 02-05 April 2007
N2  - Innovative interplanetary deep space missions, like a main belt asteroid sample
return mission, require ever larger velocity increments (∆V s) and thus ever
more demanding propulsion capabilities. Providing much larger exhaust velocities than chemical high-thrust systems, electric low-thrust space-propulsion
systems can significantly enhance or even enable such high-energy missions. In
1995, a European-Russian Joint Study Group (JSG) presented a study report
on “Advanced Interplanetary Missions Using Nuclear-Electric Propulsion”
(NEP). One of the investigated reference missions was a sample return (SR)
from the main belt asteroid (19) Fortuna. The envisaged nuclear power plant,
Topaz-25, however, could not be realized and also the worldwide developments
in space reactor hardware stalled. In this paper, we investigate, whether such
a mission is also feasible using a solar electric propulsion (SEP) system and
compare our SEP results to corresponding NEP results.
Y1  - 2007
SP  - 1
EP  - 10
ER  - 
TY  - CHAP
A1  - Dachwald, Bernd
A1  - Kahle, Ralph
A1  - Wie, Bong
T1  - Head-on impact deflection of NEAs: a case study for 99942 Apophis
T2  - Planetary Defense Conference 2007
N2  - 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
Y1  - 2007
N1  - Planetary Defense Conference 2007, Wahington D.C., USA, 05-08 March 2007
SP  - 1
EP  - 12
ER  - 
TY  - CHAP
A1  - Loeb, Horst Wolfgang
A1  - Schartner, Karl-Heinz
A1  - Dachwald, Bernd
A1  - Seboldt, Wolfgang
T1  - SEP-Sample return from a main belt asteroid
T2  - 30th International Electric Propulsion Conference
N2  - 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.
Y1  - 2007
SP  - 1
EP  - 11
ER  - 
TY  - CHAP
A1  - Dachwald, Bernd
A1  - Mengali, Giovanni
A1  - Quarta, Alessandro A
A1  - Macdonald, Malcolm
A1  - McInnes, Colin R
T1  - Optical solar sail degradation modelling
T2  - 1st International Symposium on Solar Sailing
N2  - 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.
Y1  - 2007
N1  - 1st International Symposium on Solar Sailing 27–29 June 2007, Herrsching, Germany
SP  - 1
EP  - 27
ER  - 
TY  - CHAP
A1  - Weiss, Alexander
A1  - Abanteriba, Sylvester
A1  - Esch, Thomas
T1  - Investigation of Flow Separation Inside a Conical Rocket Nozzle With the Aid of an Annular Cross Flow
T2  - Proceedings of the ASME/JSME 2007 5th Joint Fluids Engineering Conference. Volume 1: Symposia, Parts A and B
N2  - Flow separation is a phenomenon that occurs in all kinds of supersonic nozzles sometimes during run-up and shut-down operations. Especially in expansion nozzles of rocket engines with large area ratio, flow separation can trigger strong side loads that can damage the structure of the nozzle. The investigation presented in this paper seeks to establish measures that may be applied to alter the point of flow separation. In order to achieve this, a supersonic nozzle was placed at the exit plane of the conical nozzle. This resulted in the generation of cross flow surrounding the core jet flow from the conical nozzle. Due to the entrainment of the gas stream from the conical nozzle the pressure in its exit plane was found to be lower than that of the ambient. A Cold gas instead of hot combustion gases was used as the working fluid. A mathematical simulation of the concept was validated by experiment. Measurements confirmed the simulation results that due to the introduction of a second nozzle the pressure in the separated region of the conical nozzle was significantly reduced. It was also established that the boundary layer separation inside the conical nozzle was delayed thus allowing an increased degree of overexpansion. The condition established by the pressure measurements was also demonstrated qualitatively using transparent nozzle configurations.
Y1  - 2007
SN  - 0-7918-4288-6
U6  - http://dx.doi.org/10.1115/FEDSM2007-37387
N1  - Proceedings of the ASME/JSME 2007 5th Joint Fluids Engineering Conference. Volume 1: Symposia, Parts A and B. San Diego, California, USA. July 30–August 2, 2007
SP  - 1861
EP  - 1871
PB  - American Society of Mechanical Engineers (ASME)
CY  - New York
ER  - 
TY  - JOUR
A1  - Dachwald, Bernd
A1  - Seboldt, W.
A1  - Loeb, H. W
A1  - Schartner, K.-H.
T1  - Main Belt Asteroid Sample Return Mission Using Solar Electric Propulsion
JF  - Acta Astronautica. 63 (2008), H. 1-4
Y1  - 2008
SN  - 0094-5765
N1  - International Astronautical Federation Congress <58, 2007, Hyderabad> ; International Astronautical Congress <58, 2007, Hyderabad> ; IAC-07-A3.5.07
SP  - 91
EP  - 101
ER  - 
TY  - BOOK
A1  - Ley, Wilfried
T1  - Handbuch der Raumfahrttechnik / Ley, Wilfried ; Wittmann, Klaus ; Hallmann, Willi [Hrsg.]
Y1  - 2008
SN  - 978-3-446-41185-2
PB  - Hanser
CY  - München
ER  - 
TY  - JOUR
A1  - Dachwald, Bernd
A1  - Seboldt, W.
T1  - Solar Sails — Propellantless Propulsion for Near- and Medium-Term Deep-Space Missions  / W. Seboldt ; B. Dachwald
JF  - Advanced Propulsion Systems and Technologies, Today to 2020 / Claudio Bruno (ed.) ... - (Progress in Astronautics and Aeronautics Series ; 223)
Y1  - 2008
SN  - 978-1-56347-929-8
N1  - ISBN 10: 1-56347-929-X  ; American Institute of Aeronautics and Astronautics <New York, NY>
PB  - AIAA
CY  - Reston, Va.
ER  - 
TY  - JOUR
A1  - Dachwald, Bernd
A1  - Seboldt, W.
A1  - Lämmerzahl, W.
T1  - Solar Sail Propulsion: An Enabling Technology for Fundamental Physics Missions
JF  - Lasers, Clocks and Drag Free Control : Exploration of Relativistic Gravity in Space / by Hansjörg Dittus ..., eds. - ( Astrophysics and Space Science Library ; 349)
Y1  - 2008
SN  - 978-3-540-34376-9
SP  - 379
EP  - 398
PB  - Springer
CY  - Berlin [u.a.]
ER  - 
TY  - BOOK
A1  - Wittmann, Klaus
A1  - Ley, Wilfried [Hrsg.]
A1  - Hallmann, Willi [Hrsg.]
T1  - Handbuch der Raumfahrttechnik : mit 128 Tabellen / Wilfried Ley; Klaus Wittmann; Willi Hallmann (Hrsg.) 3., völlig neu bearb. und erw. Aufl.
Y1  - 2008
SN  - 978-3-446-41185-2
PB  - Hanser
CY  - München
ER  - 
TY  - BOOK
A1  - Esch, Thomas
A1  - Appel, Wolfgang
A1  - Höpke, Friedrich
T1  - Nutzfahrzeugtechnik : Grundlagen, Systeme, Komponenten ; mit 35 Tabellen / Appel, Wolfgang ; Höpke, Friedrich ... Esch, Thomas [u.a.] 5., vollst. überarb. Aufl.
Y1  - 2008
SN  - 978-3-8348-0374-0
PB  - Vieweg + Teubner
CY  - Wiesbaden
ER  - 
TY  - JOUR
A1  - Trilla, Joan
A1  - Grossen, Jürgen
A1  - Robinson, Alexander
A1  - Funke, Harald
A1  - Bosschaerts, Walter
A1  - Hendrick, Patrick
T1  - Development of a hydrogen combustion chamber for an ultra micro gas turbine
JF  - PowerMEMS 2008, 8th International Workshop on Micro and Nanotechnology for Power Generation and Energy Conversion Applications, microEMS 2008, 2nd Symposium on Micro Environmental Machine Systems, Sendai, JP, Nov 9-12, 2008
Y1  - 2008
SP  - 101
EP  - 104
ER  - 
TY  - JOUR
A1  - Robinson, A. E.
A1  - Funke, Harald
A1  - Hendrick, P.
A1  - Recker, E.
A1  - Peirs, J.
T1  - Development of a hydrogen fuelled 1 kW ultra micro gas turbine with special respect to designing, testing and mapping of the µ-scale combustor
JF  - IEEE International Conference on Sustainable Energy Technologies, 2008 : ICSET 2008 ; Singapore, 24 - 27 Nov. 2008.
Y1  - 2008
SN  - 978-1-4244-1887-9
SP  - 656
EP  - 660
PB  - IEEE
CY  - Piscataway, NJ
ER  - 
TY  - BOOK
A1  - Funke, Harald
T1  - Optimierung und Miniaturisierung der Mikro-Misch-Diffusionsverbrennung von Wasserstoff zur potentiellen Anwendung in einer Ultra-Gasturbine. Schlussbericht.
Y1  - 2008
N1  - Förderkennzeichen: 1729X05
PB  - Fachhochschule Aachen
CY  - Aachen
ER  - 
TY  - JOUR
A1  - Havermann, Marc
A1  - Haertig, J.
A1  - Rey, C.
A1  - George, A.
T1  - PIV Measurements in Shock Tunnels and Shock Tubes / Havermann, M. ; Haertig, J. ; Rey, C. ; George, A.
JF  - Particle Image Velocimetry : New Developments and Recent Applications
Y1  - 2008
SN  - 978-3-540-73528-1
N1  - Topics in applied physics. Vol 112.
SP  - 429
EP  - 442
PB  - Springer
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Havermann, Marc
A1  - Seiler, F.
A1  - Georges, A.
A1  - Srulijes, J.
T1  - Progress in Doppler picture velocimetry (DPV) / Seiler, F. ; George, A. ; Srulijes, J. ; Havermann, M.
JF  - Experiments in Fluids. 44 (2008), H. 3
Y1  - 2008
SN  - 1432-1114
SP  - 389
EP  - 395
PB  - -
ER  - 
TY  - JOUR
A1  - Funke, Harald
A1  - Rönna, Uwe
A1  - Robinson, A. E.
T1  - Development and testing of a 10 kW diffusive micromix combustor for hydrogen-fuelled μ-scale gas turbines
JF  - Proceedings of ASME Turbo Expo 2008: Power for Land, Sea and Air ; GT2008 ; June 9-13, 2008, Berlin, Germany
Y1  - 2008
N1  - GT2008-50418
SP  - 1
EP  - 8
PB  - ASME
CY  - New York, NY
ER  - 
TY  - CHAP
A1  - Christen, Marc
A1  - Bartelt, Perry
A1  - Kowalski, Julia
A1  - Stoffel, Lukus
T1  - Calculation of dense snow avalanches in three-dimensional terrain with the numerical simulation programm RAMMS
T2  - Proceedings ISSW 2008 ; International Snow Science Workshop. Whistler 2008
N2  - Numerical models have become an essential part of snow avalanche engineering. Recent
advances in understanding the rheology of flowing snow and the mechanics of entrainment and
deposition have made numerical models more reliable. Coupled with field observations and historical
records, they are especially helpful in understanding avalanche flow in complex terrain. However, the
application of numerical models poses several new challenges to avalanche engineers. A detailed
understanding of the avalanche phenomena is required to specify initial conditions (release zone
dimensions and snowcover entrainment rates) as well as the friction parameters, which are no longer
based on empirical back-calculations, rather terrain roughness, vegetation and snow properties. In this
paper we discuss these problems by presenting the computer model RAMMS, which was specially
designed by the SLF as a practical tool for avalanche engineers. RAMMS solves the depth-averaged
equations governing avalanche flow with first and second-order numerical solution schemes. A
tremendous effort has been invested in the implementation of advanced input and output features.
Simulation results are therefore clearly and easily visualized to simplify their interpretation. More
importantly, RAMMS has been applied to a series of well-documented avalanches to gauge model
performance. In this paper we present the governing differential equations, highlight some of the input
and output features of RAMMS and then discuss the simulation of the Gatschiefer avalanche that
occurred in April 2008, near Klosters/Monbiel, Switzerland.
KW  - snow
KW  - avalanche
Y1  - 2008
SP  - 709
EP  - 716
ER  - 
TY  - JOUR
A1  - Kowalski, Julia
T1  - Mathematische Murgangmodellierung
JF  - Newsletter Naturgefahren
Y1  - 2008
VL  - 2008
IS  - 2
SP  - 4
EP  - 5
ER  - 
TY  - THES
A1  - Kowalski, Julia
T1  - Two-phase Modeling of Debris Flows
Y1  - 2008
SN  - 978-3-86664-524-0
N1  - Diss., Eidgenössische Technische Hochschule ETH Zürich, Nr. 17827, 2008
PB  - Mensch und Buch
CY  - Berlin
ER  - 
TY  - CHAP
A1  - Kowalski, Julia
A1  - McElwaine, J.
T1  - Two-phase debris flow modeling
T2  - Geophysical Research Abstracts
Y1  - 2008
N1  - A-01048
ER  - 
TY  - JOUR
A1  - Polaczek, Christa
A1  - Henn, Gudrun
T1  - Gute Vorkenntnisse verkürzen die Studienzeit
JF  - Mathematikinformation : eine Zeitschrift von Begabtenförderung Mathematik e.V.
Y1  - 2008
SN  - 1612-9156
VL  - 2008
IS  - 49
SP  - 46
EP  - 50
PB  - Begabtenförderung Mathematik
CY  - Neubiberg
ER  - 
TY  - BOOK
A1  - Esch, Thomas
T1  - Verbrennungstechnik : Vorlesungsumdruck. 7. Aufl.
Y1  - 2008
PB  - Fachhochschule Aachen, Lehr- und Forschungsgebiet Thermodynamik und Verbrennungstechnik
CY  - Aachen
ER  - 
TY  - CHAP
A1  - Nowack, N.
A1  - Röth, Thilo
A1  - Bührig-Polaczek, A.
A1  - Klaus, G.
ED  - Hirsch, Jürgen
T1  - Advanced Sheet Metal Components Reinforced by Light Metal Cast Structures
T2  - Aluminium alloys : their physical and mechanical properties ; [proceedings of the 11th International Conference on Aluminium Alloys, 22 - 26 Sept. 2008, Aachen, Germany ; ICAA 11]
Y1  - 2008
SN  - 978-3-527-32367-8
IS  - 2
SP  - 2374
EP  - 2381
ER  - 
TY  - JOUR
A1  - Dachwald, Bernd
A1  - Ohndorf, A.
A1  - Gill, E.
T1  - Optimization of low-thrust Earth-Moon transfers using evolutionary neurocontrol  / Ohndorf, A. ; Dachwald, B. ; Gill, E.
JF  - IEEE Congress on Evolutionary Computation, 2009. CEC '09.
Y1  - 2009
SN  - 978-1-4244-2958-5
SP  - 358
EP  - 364
ER  - 
TY  - JOUR
A1  - Dachwald, Bernd
A1  - Carnelli, Ian
A1  - Vasile, Massimiliano
T1  - Evolutionary Neurocontrol: A Novel Method for Low-Thrust Gravity-Assist Trajectory Optimization / Carnelli, Ian ; Dachwald, Bernd ; Vasile, Massimiliano
JF  - Journal of guidance control and dynamics. 32 (2009), H. 2
Y1  - 2009
SN  - 0731-5090
SP  - 616
EP  - 625
PB  - AIAA
CY  - Reston, Va.
ER  - 
TY  - JOUR
A1  - Dachwald, Bernd
A1  - Ball, Andrew J.
A1  - Ulamec, Stephan
A1  - Price, Michael E.
T1  - A small mission for in situ exploration of a primitive binary near-Earth asteroid  / Ball, Andrew J. ; Ulamec, Stephan ; Dachwald, Bernd ; Price, Michael E. ; [u.a.]
JF  - Advances in Space Research. 43 (2009), H. 2
Y1  - 2009
SN  - 0273-1177
SP  - 317
EP  - 324
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - BOOK
A1  - Ley, Wilfried
A1  - Wittmann, Klaus
A1  - Hallmann, Willi
T1  - Handbook of space technology
Y1  - 2009
SN  - 978-0-470-69739-9
PB  - Wiley
CY  - Chichester
ER  - 
TY  - JOUR
A1  - Röth, Thilo
A1  - Nowack, Niels
A1  - Oberschelp, Christian
A1  - Lao, Bin
T1  - Gute Perspektiven für Stahl-Alumnium-Hybride im Automotivebereich / Nowack, Niels ; Oberschelp, Christian ; Lao, Bin ; Klaus, Gerald ; Bührig-Polaczek, Andreas ; Röth, Thilo
JF  - Giesserei : die Zeitschrift für Technik, Innovation und Management. 96 (2009), H. 5
Y1  - 2009
SN  - 0016-9765
SP  - 110
EP  - 123
ER  - 
TY  - JOUR
A1  - Röth, Thilo
A1  - Kern, Daniel
A1  - Kirchner, Karsten
A1  - Vietor, Thomas
T1  - Flexbody : Baukastensystem für Karosseriestrukturen / Kern, Daniel ; Röth, Thilo ; Kirchner, Karsten ; Vietor, Thomas
JF  - Mobiles : Fachzeitschrift für Konstrukteure. 35 (2009), H. 2009/2010
Y1  - 2009
SP  - 73
EP  - 75
PB  - Hochsch. für Angewandte Wiss.
CY  - Hamburg
ER  - 
TY  - CHAP
A1  - Röth, Thilo
A1  - Stark, R.
T1  - Die Rolle der virtuellen Produktentstehung bei der Integration von Karosseriesystemen
T2  - Karosseriekongress Systemintegration in der Karosserietechnik : 17. und 18. März 2009 in Baden-Baden / Kongressleitung: Reiner Stark
Y1  - 2009
SN  - 978-3-9812624-4-5
N1  - Karosseriekongress ; (2009.03.17-18 : ; Baden-Baden)
PB  - VDI-Wissensforum
CY  - Düsseldorf
ER  - 
TY  - JOUR
A1  - Wilson, T. L.
A1  - Blome, Hans-Joachim
T1  - The Pioneer anomaly and a rotating Gödel universe
JF  - Advances in Space Research
Y1  - 2009
SN  - 0273-1177
VL  - 44
IS  - 11
SP  - 1345
EP  - 1353
ER  - 
TY  - JOUR
A1  - Robinson, A. E.
A1  - Funke, Harald
A1  - Wagemakers, R.
A1  - Grossen, J.
A1  - Bosschaerts, W.
A1  - Hendrick, P.
T1  - Numerical and Experimental Investigation of a Micromix Combustor for a Hydrogen Fuelled μ-Scale Gas Turbine
JF  - Proceedings of the ASME Turbo Expo 2009 : : presented at the 2009 ASME Turbo Expo, June 8 - 12, 2009, Orlando, Florida, USA / sponsored by the International Gas Turbine Institute
Y1  - 2009
SN  - 9780791848869
N1  - GT2009-60061
SP  - 253
EP  - 262
PB  - ASME
CY  - New York, NY
ER  - 
TY  - JOUR
A1  - Pichler, A.
A1  - George, A.
A1  - Seiler, F.
A1  - Srulijes, J.
A1  - Havermann, Marc
T1  - Doppler Picture Velocimetry (DPV) applied to hypersonics
JF  - Shock Waves [Elektronische Ressource] : 26th International Symposium on Shock Waves, Volume 1 / edited by Klaus Hannemann, Friedrich Seiler
Y1  - 2009
SN  - 978-3-540-85168-4
N1  - International Symposium on Shock Waves ; (26 ; 2007.07.15-20 ; Göttingen) ; ISSW ; (26 ; 2007.07.15-20 ; Göttingen)
SP  - 503
EP  - 508
PB  - Springer
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Fischer, Jan-Thomas
A1  - Kowalski, Julia
A1  - Pudasaini, Shiva P.
A1  - Miller, S. A.
T1  - Dynamic Avalanche Modeling in Natural Terrain
JF  - International Snow Science Workshop, Davos 2009, Proceedings ; Proc. ISSW 2009
N2  - The powerful avalanche simulation toolbox RAMMS (Rapid Mass Movements) is based on a depth-averaged
hydrodynamic system of equations with a Voellmy-Salm friction relation. The two empirical friction parameters
μ and �  correspond to a dry Coulomb friction and a viscous resistance, respectively. Although μ and � lack a
proper physical explanation, 60 years of acquired avalanche data in the Swiss Alps made a systematic calibration
possible. RAMMS can therefore successfully model avalanche flow depth, velocities, impact pressure and run
out distances. Pudasaini and Hutter (2003) have proposed extended, rigorously derived model equations that
account for local curvature and twist. A coordinate transformation into a reference system, applied to the actual
mountain topography of the natural avalanche path, is performed. The local curvature and the twist of the
avalanche path induce an additional term in the overburden pressure. This leads to a modification of the Coulomb
friction, the free-surface pressure gradient, the pressure induced by the channel, and the gravity components
along and normal to the curved and twisted reference surface. This eventually guides the flow dynamics and
deposits of avalanches. In the present study, we investigate the influence of curvature on avalanche flow in
real mountain terrain. Simulations of real avalanche paths are performed and compared for the different models
approaches. An algorithm to calculate curvature in real terrain is introduced in RAMMS. This leads to a curvature
dependent friction relation in an extended version of the Voellmy-Salm model equations. Our analysis provides
yet another step in interpreting the physical meaning and significance of the friction parameters used in the
RAMMS computational environment.
KW  - snow
KW  - avalanche
Y1  - 2009
SP  - 448
EP  - 452
ER  - 
TY  - CHAP
A1  - Börner, Sebastian
A1  - Funke, Harald
A1  - Hendrick, P.
A1  - Recker, E.
T1  - LES of Jets In Cross-Flow and Application to the “Micromix” Hydrogen Combustion
T2  - XIX International Symposium on Air Breathing Engines 2009 (ISABE 2009) : Proceedings of a meeting held 7-11 September 2009, Montreal, Canada
Y1  - 2009
SN  - 9781615676064
SP  - 1555
EP  - 1561
ER  - 
TY  - CHAP
A1  - Kowalski, Julia
A1  - Bugnion, Louis
T1  - An extended shallow flow theory for natural debris flows
Y1  - 2009
N1  - 2009 Portland GSA Annual Meeting (18-21 October 2009); Geological Society of America
VL  - 41
IS  - 7
SP  - 609
EP  - 609
ER  - 
TY  - CHAP
A1  - Reimer, Lars
A1  - Wellmer, Georg
A1  - Braun, Carsten
A1  - Ballmann, Josef
T1  - Computational methods for aero-structural analysis and optimisation of aircrafts based on reduced-order structural models
T2  - MEGADESIGN and MegaOpt - German initiatives for aerodynamic simulation and optimization in aircraft design. Results of the closing symposium of the MEGADESIGN and MegaOpt projects, Braunschweig, Germany, 23 - 24 May, 2007 / Norbert Kroll ... (Eds.) Notes on numerical fluid mechanics and multidisciplinary design. Vol. 107
N2  - In this part of the MEGADESIGN project, aeroelastic effects are introduced into the aerodynamic analysis of aircrafts by coupling DLR’s flow solvers TAU and FLOWer to a Timoshenko-beam solver. The emerging aeroelastic solvers and a method for the automatic identification of Timoshenko-beam models for wing-box structures were integrated into a simulation environment enabling the combined optimisation of aerodynamic wing shape and structure.
Y1  - 2009
SN  - 978-3-642-04092-4
SP  - 135
EP  - 150
PB  - Springer
CY  - Berlin
ER  - 
TY  - BOOK
A1  - Esch, Thomas
T1  - Raumfahrtantriebe. 7. Aufl., [Umdruck]
Y1  - 2009
PB  - Fachhochschule Aachen, Lehr- und Forschungsgebiet Thermodynamik und Verbrennungstechnik
CY  - Aachen
ER  - 
TY  - CHAP
A1  - Gehler, M.
A1  - Ober-Blöbaum, S.
A1  - Dachwald, Bernd
T1  - Application of discrete mechanics and optimal control to spacecraft in non-keplerian motion around small solar system bodies
T2  - Procceedings of the 60th International Astronautical Congress
N2  - Prolonged operations close to small solar system bodies require a sophisticated control logic to minimize propellant mass and maximize operational efficiency. A control logic based on Discrete Mechanics and Optimal Control (DMOC) is proposed and applied to both conventionally propelled and solar sail spacecraft operating at an arbitrarily shaped asteroid in the class of Itokawa. As an example, stand-off inertial hovering is considered, recently identified as a challenging part of the Marco Polo mission. The approach is easily extended to stand-off orbits. We show that DMOC is applicable to spacecraft control at small objects, in particular with regard to the fact that the changes in gravity are exploited by the algorithm to optimally control the spacecraft position. Furthermore, we provide some remarks on promising developments.
KW  - Spacecraft
Y1  - 2009
SN  - 978-161567908-9
N1  - 60th International Astronautical Congress 2009, IAC 2009; Daejeon; South Korea; 12 October 2009 through 16 October 2009
SP  - 1360
EP  - 1371
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - CHAP
A1  - Dachwald, Bernd
A1  - Wurm, P.
T1  - Design concept and modeling of an advanced solar photon thruster
T2  - Advances in the Astronautical Sciences
N2  - The so-called "compound solar sail", also known as "Solar Photon Thruster" (SPT), holds the potential of providing significant performance advantages over the flat solar sail. Previous SPT design concepts, however, do not consider shadowing effects and multiple reflections of highly concentrated solar radiation that would inevitably destroy the gossamer sail film. In this paper, we propose a novel advanced SPT (ASPT) design concept that does not suffer from these oversimplifications. We present the equations that describe the thrust force acting on such a sail system and compare its performance with respect to the conventional flat solar sail.
KW  - solar sails
Y1  - 2009
SN  - 978-087703554-1
SN  - 00653438
N1  - 19th AAS/AIAA Space Flight Mechanics Meeting; Savannah, GA; United States; 8 February 2009 through 12 February 2009
SP  - 723
EP  - 740
PB  - American Astronautical Society
CY  - San Diego, Calif.
ER  - 
TY  - CHAP
A1  - Dachwald, Bernd
A1  - Wurm, P.
T1  - Mission analysis for an advanced solar photon thruster
T2  - 60th International Astronautical Congress 2009, IAC 2009
N2  - The so-called "compound solar sail", also known as "Solar Photon Thruster" (SPT), is a solar sail design concept, for which the two basic functions of the solar sail, namely light collection and thrust direction, are uncoupled. In this paper, we introduce a novel SPT concept, termed the Advanced Solar Photon Thruster (ASPT). This model does not suffer from the simplified assumptions that have been made for the analysis of compound solar sails in previous studies. We present the equations that describe the force, which acts on the ASPT. After a detailed design analysis, the performance of the ASPT with respect to the conventional flat solar sail (FSS) is investigated for three interplanetary mission scenarios: An Earth-Venus rendezvous, where the solar sail has to spiral towards the Sun, an Earth-Mars rendezvous, where the solar sail has to spiral away from the Sun, and an Earth-NEA rendezvous (to near-Earth asteroid 1996FG3), where a large orbital eccentricity change is required. The investigated solar sails have realistic near-term characteristic accelerations between 0.1 and 0.2mm/s2. Our results show that a SPT is not superior to the flat solar sail unless very idealistic assumptions are made.
KW  - Interplanetary flight
Y1  - 2009
SN  - 978-161567908-9
N1  - 60th International Astronautical Congress 2009, IAC 2009; Daejeon; South Korea; 12 October 2009 through 16 October 2009
VL  - Vol. 8
SP  - 6838
EP  - 6851
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - CHAP
A1  - Schartner, Karl-Heinz
A1  - Loeb, H. W.
A1  - Dachwald, Bernd
A1  - Ohndorf, Andreas
T1  - Perspectives of electric propulsion for outer planetary and deep space missions
T2  - European Planetary Science Congress 2009
N2  - 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].
Y1  - 2009
N1  - European Planetary Science Congress 2009, 13-18 September, Potsdam, Germany
SP  - 416
EP  - 416
ER  - 
TY  - CHAP
A1  - Spurmann, Jörn
A1  - Ohndorf, Andreas
A1  - Dachwald, Bernd
A1  - Seboldt, Wolfgang
A1  - Löb, Horst
A1  - Schartner, Karl-Heinz
T1  - Interplanetary trajectory optimization for a sep mission to Saturn
T2  - 60th International Astronautical Congress 2009
N2  - 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.
KW  - Spacecraft
KW  - Reusable Rocket Engines
KW  - Hybrid Propellants
Y1  - 2009
SN  - 9781615679089
N1  - 60th International Astronautical Congress 2009 (IAC 2009)
Held 12-16 October 2009, Daejeon, Republic of Korea.
SP  - 5234
EP  - 5248
ER  - 
TY  - CHAP
A1  - Kemper, Hans
A1  - Hellenbroich, Gereon
A1  - Esch, Thomas
T1  - Concept of an innovative passenger-car hybrid drive for European driving conditions
T2  - Hybrid vehicles and energy management : 6th symposium ; 18th and 19th February 2009, Stadthalle Braunschweig
N2  - The downsizing of spark ignition engines in conjunction with turbocharging is considered to be a promising method for reducing CO₂ emissions. Using this concept, FEV has developed a new, highly efficient drivetrain to demonstrate fuel consumption reduction and drivability in a vehicle based on the Ford Focus ST. The newly designed 1.8L turbocharged gasoline engine incorporates infinitely variable intake and outlet control timing and direct fuel injection utilizing piezo injectors centrally located. In addition, this engine uses a prototype FEV engine control system, with software that was developed and adapted entirely by FEV. The vehicle features a 160 kW engine with a maximum mean effective pressure of 22.4 bar and 34 % savings in simulated fuel consumption. During the first stage, a new electrohydraulically actuated hybrid transmission with seven forward gears and one reverse gear and a single dry starting clutch will be integrated. The electric motor of the hybrid is directly connected to the gear set of the transmission. Utilizing the special gear set layout, the electric motor can provide boost during a change of gears, so that there is no interruption in traction. Therefore, the transmission system combines the advantages of a double clutch controlled gear change (gear change without an interruption in traction) with the efficient, cost-effective design of an automated manual transmission system. Additionally, the transmission provides a purely electric drive system and the operation of an air-conditioning compressor during the engine stop phases. One other alternative is through the use of CAI (Controlled Auto Ignition), which incorporates a process developed by FEV for controlled compression ignition.
Y1  - 2009
SN  - 978-3-937655-20-8
SP  - 264
EP  - 287
PB  - Gesamtzentrum für Verkehr (GZVB)
CY  - Braunschweig
ER  - 
TY  - CHAP
A1  - Funke, Harald
A1  - Esch, Thomas
A1  - Roosen, Peter
ED  - Bartz, Wilfried J.
T1  - Using motor gasoline for aircrafts - coping with growing bio-fuel-caused risks by understanding cause-effect relationship
T2  - Fuels 2009 : mineral oil based and alternative fuels ; 7th international colloquium ; January 14 - 15, 2009
N2  - The utilisation of vehicle-oriented gasoline in general aviation is very desirable for both ecological and economical reasons, as well as for general considerations of availability. As of today vehicle fuels may be used if the respective engine and cell are certified for such an operation. For older planes a supplementary technical certificate is provided for gasoline mixtures with less than 1 % v/v ethanol only, though. Larger admixtures of ethanol may lead to sudden engine malfunction and should be considered as considerable security risks. Major problems are caused by the partially ethanol non-withstanding materials, a necessarily changed stochiometric adjustment of the engine for varying ethanol shares and the tendency for phase separation in the presence of absorbed water. The concepts of the flexible fuel vehicles are only partially applicable in the view of air security.
Y1  - 2009
SN  - 978-3-924813-75-8
SP  - 237
EP  - 244
PB  - Technische Akademie Esslingen (TAE)
CY  - Ostfildern
ER  - 
TY  - JOUR
A1  - Scholz, A.
A1  - Ley, Wilfried
A1  - Dachwald, Bernd
A1  - Miau, J. J.
A1  - Juang, J. C.
T1  - Flight results of the COMPASS-1 picosatellite mission
JF  - Acta Astronautica. 67 (2010), H. 9-10
Y1  - 2010
SN  - 0094-5765
SP  - 1289
EP  - 1298
ER  - 
TY  - JOUR
A1  - Blome, Hans-Joachim
A1  - Chicone, Carmen
A1  - Hehl, Friedrich W.
A1  - Mashhoon, Bahram
T1  - Nonlocal modification of Newtonian gravity
JF  - Physical Review D
Y1  - 2010
SN  - 0556-2821
N1  - 11 pages
VL  - 81
IS  - 6
SP  - 065020
ER  - 
TY  - JOUR
A1  - Esch, Thomas
T1  - Trends in der Nutzfahrzeugantriebstechnik
JF  - Motortechnische Zeitschrift (MTZ)
Y1  - 2010
SN  - 0024-8525
U6  - http://dx.doi.org/10.1007/bf03225608
VL  - 71
IS  - 10
SP  - 652
EP  - 658
PB  - Springer Nature
CY  - Basel
ER  - 
TY  - JOUR
A1  - Maiwald, Volker
A1  - Dachwald, Bernd
T1  - Mission Design for a Multiple-Rendezvous Mission to Jupiter's Trojans
Y1  - 2010
N1  - COSPAR 2010 ; 38th COSPAR Scientific Assembly. Held 18-25 July 2010 in Bremen, Germany [Abstract]
SP  - 3
ER  - 
TY  - JOUR
A1  - Börner, Sebastian
A1  - Funke, Harald
A1  - Hendrick, P.
A1  - Recker, E.
T1  - Control system modifications for a hydrogen fuelled gas-turbine
JF  - ISROMAC 13, 13th International Symposium on Transport Phenomena and Dynamics of Rotating Machinery, Honolulu, HI, US, Apr 4-7, 2010
Y1  - 2010
SN  - 978-1-617-38848-4
SP  - 665
EP  - 670
PB  - Curran
CY  - Red Hook, NY
ER  - 
TY  - JOUR
A1  - Funke, Harald
A1  - Robinson, A. E.
A1  - Hendrick, P.
A1  - Wagemakers, R.
T1  - Design and Testing of a Micromix Combustor With Recuperative Wall Cooling for a Hydrogen Fuelled µ-Scale Gas Turbine
JF  - Proceedings of the ASME Turbo Expo 2010 : presented at the 2010 ASME Turbo Expo, June 14 - 18, 2010, Glasgow, UK / sponsored by the International Gas Turbine Institute / Vol. 5: Industrial and cogeneration ; microturbines and small turbomachinery ; oil and gas applications ; wind turbine technology
Y1  - 2010
SN  - 978-0-7918-4400-7
N1  - GT2010-23453 ; ASME Turbo Expo ; (Glasgow) : 2010.06.14-18
SP  - 587
EP  - 596
PB  - ASME
CY  - New York, NY
ER  - 
TY  - BOOK
A1  - Lemaitre, George
A1  - Blome, Hans-Joachim
ED  - Blome, Hans-Joachim
T1  - Von der klassischen Kosmologie zum Quantenkosmos
Y1  - 2010
SN  - 978-3-8171-3304-8
N1  - Ostwalds Klassiker der exakten Wissenschaften ; Bd. 304
PB  - Deutsch
CY  - Frankfurt am Main
ER  - 
TY  - JOUR
A1  - Lettini, Antonio
A1  - Havermann, Marc
A1  - Guidetti, Marco
A1  - Fornaciari, Andrea
T1  - Improved functionalities and energy saving potential on mobile machines combining electronics with flow sharing valve and variable displacement pump
JF  - IFK 7, 7th International Fluid Power Conference, Efficiency through Fluid Power, 7. Internationales Fluidtechnisches Kolloquium, Workshop Proceedings, Vol. 3, Aachen, DE, 22.-24. Mar, 2010
Y1  - 2010
SN  - 978-3-940565-92-1
N1  - IFK, 7, Internationales Fluidtechnisches Kolloquium, 7., Aachen, DE, 2010-03-22 - 2010-03-24
SP  - 103
EP  - 114
PB  - -
ER  - 
TY  - JOUR
A1  - Funke, Harald
A1  - Börner, Sebastian
A1  - Robinson, A.
A1  - Hendrick, P.
A1  - Recker, E.
T1  - Low NOx H2 combustion for industrial gas turbines of various power ranges
JF  - 5th International Gas Turbine Conference ETN-IGTC, ETN-2010-42, Brussels, Belgium, October 2010
Y1  - 2010
ER  - 
TY  - JOUR
A1  - Recker, Elmar
A1  - Bosschaerts, Walter
A1  - Wagemakers, Rolf
A1  - Hendrick, Patrick
A1  - Funke, Harald
A1  - Börner, Sebastian
T1  - Experimental study of a round jet in cross-flow at low momentum ratio
JF  - 15th International Symposium on Applications of Laser Techniques to Fluid Mechanics Lisbon, Portugal, 05-08 July, 2010 - 1
Y1  - 2010
SP  - 1
EP  - 13
ER  - 
TY  - THES
A1  - Kowalski, Julia
T1  - Streamline estimation from sparsely sampled q-space Magnetic Resonance data
Y1  - 2010
N1  - Master Thesis in Medical Physics, ETH Zurich
ER  - 
TY  - CHAP
A1  - Kapoor, Hrshi
A1  - Boller, Christian
A1  - Giljohann, Sebastian
A1  - Braun, Carsten
T1  - Strategies for structural health monitoring implementation potential assessment in aircraft operational life extension considerations
T2  - 2nd International Symposium on NDT in Aerospace : November 22-24, 2010 Hamburg, Germany
Y1  - 2010
SN  - 978-3-940283-28-3
PB  - Dt. Gesellschaft für Zerstörungsfreie Prüfung
CY  - Berlin
ER  - 
TY  - CHAP
A1  - Kapoor, Hrshi
A1  - Braun, Carsten
A1  - Boller, Christian
ED  - Casciati, Fabio
T1  - Modelling and optimisation of maintenance intervals to realize structural health monitoring applications on aircraft
T2  - Structural health monitoring 2010 : proceedings of the Fifth European Workshop on Structural Health Monitoring held at Sorrento, Naples, Italy, June 28 - July 4, 2010 ; [EWSHM]
Y1  - 2010
SN  - 978-1-60595-024-2
SP  - 55
EP  - 63
PB  - DEStech Publ.
CY  - Lancaster, Pa.
ER  - 
TY  - CHAP
A1  - Reimer, Lars
A1  - Braun, Carsten
A1  - Wellmer, Georg
A1  - Behr, Marek
A1  - Ballmann, Josef
T1  - Development of a modular method for computational aero-structural analysis of aircraft
T2  - Summary of flow modulation and fluid-structure interaction findings. Results of the Collaborative Research Center SFB 401 at the RWTH Aachen University, Aachen, Germany, 1997-2008 / ed.: Wolfgang Schröder. Notes on numerical fluid mechanics and multidisciplinary design. Vol. 109
Y1  - 2010
SN  - 978-3-642-04087-0
SP  - 205
EP  - 238
PB  - Springer
CY  - Berlin
ER  - 
TY  - BOOK
A1  - Appel, Wolfgang
A1  - Brähler, Hermann
A1  - Dahlhaus, Ulrich
A1  - Esch, Thomas
A1  - Kopp, Stephan
A1  - Rhein, Bernd
T1  - Nutzfahrzeugtechnik : Grundlagen, Systeme, Komponenten. 6., überarb. Aufl.
Y1  - 2010
SN  - 978-3-8348-9757-2
PB  - Vieweg + Teubner
CY  - Wiesbaden
ER  - 
TY  - CHAP
A1  - Pasligh, N.
A1  - Funke, D.
A1  - Röth, Thilo
A1  - Krack, R.
T1  - Leichtbau Quertrager als Stahlblech-Aluminiumdruckguss-Hybrid - Von der numerischen Berechnung bis zum realen Prototypen
T2  - VDI BERICHTE
Y1  - 2010
SN  - 978-3-18-092107-5
N1  - 15. Kongress SIMVEC Berechnung und Simulation im Fahrzeugbau, 
Baden-Baden, 16. und 17. November 2010
PB  - VDI Verlag
CY  - Düsseldorf
ER  - 
TY  - CHAP
A1  - Borggräfe, Andreas
A1  - Dachwald, Bernd
T1  - Mission performance evaluation for solar sails using a refined SRP force model with variable optical coefficients
T2  - 2nd International Symposium on Solar Sailing
N2  - 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.
Y1  - 2010
N1  - 2nd International Symposium on Solar Sailing, ISSS 2010, 2010-07-20 - 2010-07-22. New York City College of Technology of the City University of New York, USA
SP  - 1
EP  - 6
ER  - 
TY  - CHAP
A1  - Dachwald, Bernd
T1  - Solar sail dynamics and control
T2  - Encyclopedia of Aerospace Engineering
N2  - 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.
KW  - solar sail
KW  - sailcraft
KW  - orbital dynamics
KW  - orbit control
KW  - attitude dynamics
Y1  - 2010
U6  - http://dx.doi.org/10.1002/9780470686652.eae292
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - RPRT
A1  - Esch, Thomas
A1  - Funke, Harald
A1  - Roosen, Petra
T1  - SIoBiA – Safety Implications of Biofuels in Aviation
N2  - Biofuels potentially interesting also for aviation purposes are predominantly liquid fuels produced from biomass. The most common biofuels today are biodiesel and bioethanol. Since diesel engines are rather rare in aviation this survey is focusing on ethanol admixed to gasoline products.
The Directive 2003/30/EC of the European Parliament and the Council of May 8th 2003 on the promotion of the use of biofuels or other renewable fuels for transport encourage a growing admixture of biogenic fuel components to fossil automotive gasoline. Some aircraft models equipped with spark ignited piston engines are approved for operation with automotive gasoline, frequently called “MOGAS” (motor gasoline). The majority of those approvals is limited to MOGAS compositions that do not contain methanol or ethanol beyond negligible amounts. In the past years (bio-)MTBE or (bio-)ETBE have been widely used as blending component of automotive gasoline whilst the usage of low-molecular alcohols like methanol or ethanol has been avoided due to the handling problems especially with regard to the strong affinity for water. With rising mandatory bio-admixtures the conversion of the basic biogenic ethanol to ETBE, causing a reduction of energetic payoff, becomes more and more unattractive. Therefore the direct ethanol admixture is accordingly favoured.
Due to the national enforcements of the directive 2003/30/EC more oxygenates produced from organic materials like bioethanol have started to appear in automotive gasolines already. The current fuel specification EN 228 already allows up to 3 % volume per volume (v/v) (bio-)methanol or up to 5 % v/v (bio-)ethanol as fuel components. This is also roughly the amount of biogenic components to comply with the legal requirements to avoid monetary penalties for producers and distributors of fuels.
Since automotive fuel is cheaper than the common aviation gasoline (AVGAS), creates less problems with lead deposits in the engine, and in general produces less pollutants it is strongly favoured by pilots. But being designed for a different set of usage scenarios the use of automotive fuel with low molecular alcohols for aircraft operation may have adverse effects in aviation operation. Increasing amounts of ethanol admixtures impose various changes in the gasoline’s chemical and physical properties, some of them rather unexpected and not within the range of flight experiences even of long-term pilots.
Y1  - 2010
N1  - Analysis of the safety implications of the use of biofuels (ethanol admixture) for piston engines and general aviation aircraft and assessment of potential environmental benefits.
PB  - EASA
CY  - Köln
ER  - 
TY  - JOUR
A1  - Esch, Thomas
T1  - Trends in commercial vehicle powertrains
JF  - ATZautotechnology
N2  - Low emission zones and truck bans, the rising price of diesel and increases in road tolls: all of these factors are putting serious pressure on the transport industry. Commercial vehicle manufacturers and their suppliers are in the process of identifying new solutions to these challenges as part of their efforts to meet the EEV (enhanced environmentally friendly vehicle) limits, which are currently the most robust European exhaust and emissions standards for trucks and buses.
KW  - European Transient Cycle
KW  - Common Rail Injection System
KW  - Commercial Vehicle
KW  - Selective Catalytic Reduction
KW  - Diesel Engine
Y1  - 2010
U6  - http://dx.doi.org/10.1007/BF03247185
SN  - 2192-886X
VL  - 2010
IS  - 10
SP  - 26
EP  - 31
PB  - Vieweg & Sohn
CY  - Wiesbaden
ER  - 
TY  - JOUR
A1  - Christen, Marc
A1  - Kowalski, Julia
A1  - Bartelt, Perry
T1  - RAMMS: Numerical simulation of dense snow avalanches in three-dimensional terrain
JF  - Cold Regions Science and Technology
N2  - Numerical avalanche dynamics models have become an essential part of snow engineering. Coupled with field observations and historical records, they are especially helpful in understanding avalanche flow in complex terrain. However, their application poses several new challenges to avalanche engineers. A detailed understanding of the avalanche phenomena is required to construct hazard scenarios which involve the careful specification of initial conditions (release zone location and dimensions) and definition of appropriate friction parameters. The interpretation of simulation results requires an understanding of the numerical solution schemes and easy to use visualization tools. We discuss these problems by presenting the computer model RAMMS, which was specially designed by the SLF as a practical tool for avalanche engineers. RAMMS solves the depth-averaged equations governing avalanche flow with accurate second-order numerical solution schemes. The model allows the specification of multiple release zones in three-dimensional terrain. Snow cover entrainment is considered. Furthermore, two different flow rheologies can be applied: the standard Voellmy–Salm (VS) approach or a random kinetic energy (RKE) model, which accounts for the random motion and inelastic interaction between snow granules. We present the governing differential equations, highlight some of the input and output features of RAMMS and then apply the models with entrainment to simulate two well-documented avalanche events recorded at the Vallée de la Sionne test site.
KW  - RAMMS
KW  - snow
KW  - avalanche
Y1  - 2010
U6  - http://dx.doi.org/10.1016/j.coldregions.2010.04.005
SN  - 1872-7441
VL  - 63
IS  - 1-2
SP  - 1
EP  - 14
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Christen, Marc
A1  - Bartelt, Perry
A1  - Kowalski, Julia
T1  - Back calculation of the In den Arelen avalanche with RAMMS: Interpretation of model results
JF  - Annals of Glaciology
N2  - Two- and three-dimensional avalanche dynamics models are being increasingly used in hazard-mitigation studies. These models can provide improved and more accurate results for hazard mapping than the simple one-dimensional models presently used in practice. However, two- and three-dimensional models generate an extensive amount of output data, making the interpretation of simulation results more difficult. To perform a simulation in three-dimensional terrain, numerical models require a digital elevation model, specification of avalanche release areas (spatial extent and volume), selection of solution methods, finding an adequate calculation resolution and, finally, the choice of friction parameters. In this paper, the importance and difficulty of correctly setting up and analysing the results of a numerical avalanche dynamics simulation is discussed. We apply the two-dimensional simulation program RAMMS to the 1968 extreme avalanche event In den Arelen. We show the effect of model input variations on simulation results and the dangers and complexities in their interpretation.
KW  - avalanche
Y1  - 2010
SN  - 1727-5644
U6  - http://dx.doi.org/10.3189/172756410791386553
VL  - 51
IS  - 54
SP  - 161
EP  - 168
PB  - Cambridge University Press
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Fornaciari, Andrea
A1  - Guidetti, Marco
A1  - Havermann, Marc
A1  - Lettini, Antonio
T1  - Maccine mobili più efficienti
JF  - Fluidotecnica
N2  - Secondo le attuali normative tutte le macchine mobili, entro il 2012, dovranno essere soggette a un incremento di efficienza energetica. Un’evoluzione del sistema idraulico potrà contribuire in maniera significativa al miglioramento richiesto. Elettronica e idraulica sempre più protagoniste.
Y1  - 2010
IS  - 345
SP  - 11
EP  - 14
PB  - Quine Business Publisher
CY  - Milano
ER  - 
TY  - CHAP
A1  - Havermann, Marc
A1  - Seiler, F.
A1  - Henning, P.
ED  - Dillmann, Andreas
ED  - Heller, Gerd
ED  - Klaas, Michael
ED  - Kreplin, Hans-Peter
ED  - Nitsche, Wolfgang
ED  - Schröder, Wolfgang
T1  - Shock Tunnel Experiments and CFD Simulation of Lateral Jet Interaction in Hypersonic Flows
T2  - New Results in Numerical and Experimental Fluid Mechanics VII; Contributions to the 16th STAB/DGLR Symposium Aachen, Germany 2008
Y1  - 2010
SN  - 9783642142437
U6  - http://dx.doi.org/10.1007/978-3-642-14243-7_45
N1  - Notes on numerical fluid mechanics and multidisciplinary design 112
SP  - 365
EP  - 372
PB  - Springer
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Esch, Thomas
A1  - Funke, Harald
A1  - Roosen, Peter
A1  - Jarolimek, Ulrich
T1  - Biogene Automobilkraftstoffe in der allgemeinen Luftfahrt
JF  - Motortechnische Zeitschrift (MTZ).
Y1  - 2011
SN  - 0024-8525
U6  - http://dx.doi.org/10.1365/s35146-011-0013-7
VL  - 72
IS  - 1
SP  - 54
EP  - 59
PB  - Springer Nature
CY  - Basel
ER  - 
TY  - JOUR
A1  - Robinson, A. E.
A1  - Funke, Harald
A1  - Hendrick, P.
T1  - Design and Testing of a Micromix Combustor With Recuperative Wall Cooling for a Hydrogen Fueled µ-Scale Gas Turbine
JF  - Journal of engineering for gas turbines and power
Y1  - 2011
SN  - 1528-8919
VL  - 133
IS  - 8
PB  - ASME
CY  - New York
ER  - 
TY  - JOUR
A1  - Scholz, Christina
A1  - Romagnoli, Daniele
A1  - Dachwald, Bernd
A1  - Theil, Stephan
T1  - Performance analysis of an attitude control system for solar sails using sliding masses
JF  - Advances in Space Research
Y1  - 2011
SN  - 0273-1177
VL  - 48
IS  - 11
SP  - 1822
EP  - 1835
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Dachwald, Bernd
A1  - Wurm, Patrick
T1  - Mission analysis and performance comparison for an Advanced Solar Photon Thruster
JF  - Advances in Space Research
Y1  - 2011
SN  - 0273-1177
VL  - 48
IS  - 11
SP  - 1858
EP  - 1868
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - BOOK
A1  - Schmitz, Günter
T1  - Elektrotechnik : Grundlagen der Elektrotechnik für Ingenieur-Studenten
Y1  - 2011
SN  - 978-87-7681-786-2
N1  - nach Registrierung frei zugänglich
PB  - Ventus Publ.
CY  - Frederiksberg
ER  - 
TY  - BOOK
A1  - Schmitz, Günter
T1  - Elektronik : Grundlagen der Elektronik für Ingenieurstudenten
Y1  - 2011
SN  - 978-87-7681-832-6
N1  - nach Registrierung frei zugänglich
PB  - Ventus Publ.
CY  - Frederiksberg
ER  - 
TY  - JOUR
A1  - Funke, Harald
A1  - Börner, Sebastian
A1  - Falk, F.
A1  - Hendrick, P.
T1  - Control system modifications and their effects on the operation of a hydrogen-fueled Auxiliary Power Unit
JF  - XX international symposium on air breathing engines 2011 : ISABE 2011, Gothenburg, Sweden, 12-16 September, 2011. Vol. 2.
Y1  - 2011
SN  - 9781618391803
N1  - 20th International Symposium on Air Breathing Engines 2011 : (ISABE 2011) : Gothenburg, Sweden, 12-16 September, 2011.
SP  - 929
EP  - 938
PB  - American Institute of Aeronautics and Astronautics
CY  - Reston, VA
ER  - 
TY  - JOUR
A1  - Funke, Harald
A1  - Börner, Sebastian
A1  - Krebs, W.
A1  - Wolf, E.
T1  - Experimental Characterization of Low NOx Micromix Prototype Combustors for Industrial Gas Turbine Applications
JF  - ASME Turbo Expo 2011 ; Vancouver, Canada, June 6-10, 2011
Y1  - 2011
N1  - GT2011-45305
ER  - 
TY  - JOUR
A1  - Funke, Harald
A1  - Recker, E.
A1  - Bosschaerts, W.
A1  - Boonen, Q.
A1  - Börner, Sebastian
T1  - Parametrical study of the „Micromix“ hydrogen combustion principle
JF  - 10th International Symposium on Experimental and Computational Aerothermodynamics of Internal Flows, ISAIF10-049, Brussels, Belgium, 4-7 July 2011
Y1  - 2011
ER  - 
TY  - JOUR
A1  - Esch, Thomas
A1  - Funke, Harald
A1  - Roosen, Peter
A1  - Jarolimek, Ulrich
T1  - Biogenic Vehicle Fuels in General Aviation Aircrafts
JF  - MTZ worldwide. 72 (2011), H. 1
Y1  - 2011
N1  - recherchierbar für Angehörige der FH Aachen
SP  - 38
EP  - 43
PB  - Springer Automotive Media
CY  - Wiesbaden
ER  - 
TY  - CHAP
A1  - Knobloch, V.
A1  - Kowalski, Julia
A1  - Bösiger, P.
A1  - Kozerke, S.
T1  - Probabilistic Streamline Estimation from Accelerated Fourier Velocity Encoded Measurements
T2  - Proceedings of the 19th ISMRM International Society for Magnetic Resonance in Medicine
Y1  - 2011
N1  - ISMRM 19th Annual Meeting & Exhibition in Montréal, Québec, Canada
SP  - 1215
EP  - 1215
ER  - 
TY  - JOUR
A1  - Bühler, Yves
A1  - Christen, Marc
A1  - Kowalski, Julia
A1  - Bartelt, Perry
T1  - Sensitivity of snow avalanche simulations to digital elevation model quality and resolution
JF  - Annals of Glaciology
N2  - Digital elevation models (DEMs), represent the three-dimensional terrain and are the basic input for numerical snow avalanche dynamics simulations. DEMs can be acquired using topographic maps or remote-sensing technologies, such as photogrammetry or lidar. Depending on the acquisition technique, different spatial resolutions and qualities are achieved. However, there is a lack of studies that investigate the sensitivity of snow avalanche simulation algorithms to the quality and resolution of DEMs. Here, we perform calculations using the numerical avalance dynamics model RAMMS, varying the quality and spatial resolution of the underlying DEMs, while holding the simulation parameters constant. We study both channelized and open-terrain avalanche tracks with variable roughness. To quantify the variance of these simulations, we use well-documented large-scale avalanche events from Davos, Switzerland (winter 2007/08), and from our large-scale avalanche test site, Valĺee de la Sionne (winter 2005/06). We find that the DEM resolution and quality is critical for modeled flow paths, run-out distances, deposits, velocities and impact pressures. Although a spatial resolution of ~25 m is sufficient for large-scale avalanche modeling, the DEM datasets must be checked carefully for anomalies and artifacts before using them for dynamics calculations.
KW  - snow
KW  - avalanche
Y1  - 2011
SN  - 1727-5644
VL  - 52
IS  - 58
SP  - 72
EP  - 80
PB  - Cambridge University Press
CY  - Cambridge
ER  - 
TY  - CHAP
A1  - Olaru, Alexandra Maria
A1  - Kowalski, Julia
A1  - Sethi, Vaishali
A1  - Blümich, Bernhard
T1  - Fluid Transport in Porous Media probed by Relaxation-Exchange NMR
T2  - 2011 Fall Meeting, AGU, San Francisco, Calif., 5-9 Dec.
Y1  - 2011
N1  - H12B-07; American Geophysical Union
ER  - 
TY  - CHAP
A1  - Funke, Harald
A1  - Börner, Sebastian
A1  - Hendrick, P.
A1  - Recker, E.
T1  - Modification and testing of an engine and fuel control system for a hydrogen fuelled gas turbine
T2  - Progress in Propulsion Physics. Vol. 2
Y1  - 2011
SN  - 978-2-7598-0673-7
SP  - 475
EP  - 486
PB  - EDP Sciences
CY  - Les Ulis
ER  - 
TY  - CHAP
A1  - Dahmann, Peter
T1  - Stemme S10 VTX als multifunktionales Forschungsflugzeug
T2  - Deutscher Luft- und Raumfahrtkongress 2011 : Bremen, 27. bis 29. September 2011 ; Tagungsband
Y1  - 2011
SN  - 978-3-9321-8274-7
SP  - 357
EP  - 364
PB  - Dt. Gesellschaft für Luft- und Raumfahrt
CY  - Bonn
ER  - 
TY  - CHAP
A1  - Thenent, N. E.
A1  - Dahmann, Peter
T1  - Increasing aircraft design flexibility ‐ The development of a hydrostatic transmission for gliders with self‐launching capability
T2  - Deutscher Luft- und Raumfahrtkongress 2011 : Bremen, 27. bis 29. September 2011 ; Tagungsband
Y1  - 2011
SN  - 978-3-9321-8274-7
SP  - 865
EP  - 883
PB  - Dt. Gesellschaft für Luft- und Raumfahrt
CY  - Bonn
ER  - 
TY  - CHAP
A1  - Thenent, N. E.
A1  - Dahmann, Peter
T1  - Hydrostatic propeller drive
T2  - Proceedings of the conference : 18 - 20 May, 2011 Tampere, Finland / the Twelth Scandinavian International Conference on Fluid Power, SICFP'11. Ed.: Harri Sairiala ... Vol. 1
Y1  - 2011
SN  - 978-952-15-2517-9
SP  - 217
EP  - 227
CY  - Tampere
ER  - 
TY  - BOOK
A1  - Esch, Thomas
T1  - Verbrennungstechnik : Vorlesungsumdruck. 8. Aufl.
Y1  - 2011
PB  - Fachhochschule Aachen, Lehr- und Forschungsgebiet Thermodynamik und Verbrennungstechnik
CY  - Aachen
ER  - 
TY  - CHAP
A1  - Lao, B.
A1  - Bührig-Polaczek, A.
A1  - Röth, Thilo
ED  - Wielage, Bernhard
T1  - Funktionsintegrierte Leichtbaustrukturen in gussintensiver Metall-Hybridbauweise
T2  - Verbundwerkstoffe und Werkstoffverbunde: Tagungsband zum 18. Symposium ; 30.03.2011 bis 01.04.2011, Chemnitz
Y1  - 2011
SN  - 978-3-00-033801-4
N1  - Schriftenreihe Werkstoffe und werkstofftechnische Anwendungen ; 41
SP  - 413
EP  - 421
PB  - Eigenverlag
CY  - Chemnitz
ER  - 
TY  - CHAP
A1  - Dachwald, Bernd
A1  - Xu, Changsheng
A1  - Feldmann, Marco
A1  - Plescher, Engelbert
T1  - IceMole : Development of a novel subsurface ice probe and testing of the first prototype on the Morteratsch Glacier
T2  - EGU General Assembly 2011 Vienna | Austria | 03 – 08 April 2011
N2  - We present the novel concept of a combined drilling and melting probe for subsurface ice research. This probe, named “IceMole”, is currently developed, built, and tested at the FH Aachen University of Applied Sciences’ Astronautical Laboratory. Here, we describe its first prototype design and report the results of its field tests on the Swiss Morteratsch glacier. Although the IceMole design is currently adapted to terrestrial glaciers and ice shields, it may later be modified for the subsurface in-situ investigation of extraterrestrial ice, e.g., on Mars, Europa, and Enceladus. If life exists on those bodies, it may be present in the ice (as life can also be found in the deep ice of Earth).
Y1  - 2011
ER  - 
TY  - CHAP
A1  - Loeb, Horst W.
A1  - Schartner, Karl-Heinz
A1  - Dachwald, Bernd
A1  - Ohndorf, Andreas
A1  - Seboldt, Wolfgang
T1  - An Interstellar – Heliopause mission using a combination of solar/radioisotope electric propulsion
T2  - Presented at the 32nd International Electric Propulsion Conference
N2  - 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 travelling 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 ESA.Two propulsion options for the mission have been proposed and discussed so far: the solar sail propulsion and the ballistic/radioisotope electric propulsion. As a further alternative, we here investigate a combination of solar-electric propulsion and radioisotope-electric propulsion. The solar-electric propulsion stage consists of six 22 cm 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 BOM is provided by a light-weight solar array. The REP-stage consists of four space-proven 10 cm diameter “RIT-10” ion thrusters that will be operating one after the other for 9 yrs in total. Four advanced radioisotope generators provide 648 W at BOM. The scientific instrument package is oriented at earlier studies. For its mass and electric power requirement 35 kg and 35 W are assessed, respectively. Optimized trajectory calculations, treated in a separate contribution, are based on our “InTrance” method.The program yields a burn out of the REP stage in a distance of 79.6 AU for a usage of 154 kg of Xe propellant. With a C3 = 45,1 (km/s)2 a heliocentric probe velocity of 10 AU/yr is reached at this distance, provided a close Jupiter gravity assist adds a velocity increment of 2.7 AU/yr. A transfer time of 23.8 yrs results for this scenario requiring about 450 kg Xe for the SEP stage, jettisoned at 3 AU. We interpret the SEP/REP propulsion as a competing alternative to solar sail and ballistic/REP propulsion. Omiting a Jupiter fly-by even allows more launch flexibility, leaving the mission duration in the range of the ESA specification.
Y1  - 2011
N1  - 32nd International Electric Propulsion Conference, 11-15 September. Wiesbaden, Germany
SP  - 1
EP  - 7
ER  - 
TY  - CHAP
A1  - Ohndorf, Andreas
A1  - Dachwald, Bernd
A1  - Seboldt, Wolfgang
A1  - Schartner, Karl-Heinz
T1  - Flight times to the heliopause using a combination of solar and radioisotope electric propulsion
T2  - 32nd International Electric Propulsion Conference
N2  - 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".
KW  - low-thrust trajectory optimization
KW  - heliosphere
KW  - ion propulsion
Y1  - 2011
N1  - IEPC-2011-051
32nd International Electric Propulsion Conference,September 11–15, 2011
Wiesbaden, Germany
SP  - 1
EP  - 12
ER  - 
TY  - BOOK
A1  - Schmitz, Günter
T1  - Elektronik im Kraftfahrzeug : Innovationen bei System und Komponenten ; mit 7 Tabellen / Hrsg.: Schmitz, Günter
Y1  - 2012
SN  - 978-3-8169-3110-2
N1  - Haus der Technik ; Bd. 123
PB  - expert-Verl.
CY  - Renningen
ER  - 
TY  - GEN
A1  - Baumgartner, Thomas
A1  - Wunderlich, Florian
A1  - Jaunich, Arthur
A1  - Sato, Tomoo
A1  - Bundy, Georg
A1  - Grießmann, Nadine
A1  - Kowalski, Julia
A1  - Burghardt, Stefan
A1  - Hanebrink, Jörg
T1  - Lighting the way: Perspectives on the global lighting market
Y1  - 2012
CY  - McKinsey
ET  - 2nd ed.
ER  - 
TY  - JOUR
A1  - Olaru, Alexandra Maria
A1  - Kowalski, Julia
A1  - Sethi, Vaishali
A1  - Blümich, Bernhard
T1  - Exchange relaxometry of flow at small Péclet numbers in a glass bead pack
JF  - Journal of Magnetic Resonance (JMR)
N2  - In this paper we consider low Péclet number flow in bead packs. A series of relaxation exchange experiments has been conducted and evaluated by ILT analysis. In the resulting correlation maps, we observed a collapse of the signal and a translation towards smaller relaxation times with increasing flow rates, as well as a signal tilt with respect to the diagonal. In the discussion of the phenomena we present a mathematical theory for relaxation exchange experiments that considers both diffusive and advective transport. We perform simulations based on this theory and discuss them with respect to the conducted experiments.
KW  - NMR exchange relaxometry
KW  - Low-field NMR
Y1  - 2012
U6  - http://dx.doi.org/10.1016/j.jmr.2012.04.015
SN  - 1096-0856
VL  - 220
SP  - 32
EP  - 44
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Fischer, Jan-Thomas
A1  - Kowalski, Julia
A1  - Pudasaini, Shiva P.
T1  - Topographic curvature effects in applied avalanche modelling
JF  - Cold Regions Science and Technology
N2  - This paper describes the implementation of topographic curvature effects within the RApid Mass MovementS (RAMMS) snow avalanche simulation toolbox. RAMMS is based on a model similar to shallow water equations with a Coulomb friction relation and the velocity dependent Voellmy drag. It is used for snow avalanche risk assessment in Switzerland. The snow avalanche simulation relies on back calculation of observed avalanches. The calibration of the friction parameters depends on characteristics of the avalanche track. The topographic curvature terms are not yet included in the above mentioned classical model. Here, we fundamentally improve this model by mathematically and physically including the topographic curvature effects. By decomposing the velocity dependent friction into a topography dependent term that accounts for a curvature enhancement in the Coulomb friction, and a topography independent contribution similar to the classical Voellmy drag, we construct a general curvature dependent frictional resistance, and thus propose new extended model equations. With three site-specific examples, we compare the apparent frictional resistance of the new approach, which includes topographic curvature effects, to the classical one. Our simulation results demonstrate substantial effects of the curvature on the flow dynamics e.g., the dynamic pressure distribution along the slope. The comparison of resistance coefficients between the two models demonstrates that the physically based extension presents an improvement to the classical approach. Furthermore a practical example highlights its influence on the pressure outline in the run out zone of the avalanche. Snow avalanche dynamics modeling natural terrain curvature centrifugal force friction coefficients.
KW  - Snow
KW  - Avalanche
Y1  - 2012
U6  - http://dx.doi.org/10.1016/j.coldregions.2012.01.005
SN  - 1872-7441
VL  - 74-75
SP  - 21
EP  - 30
PB  - Elsevier
CY  - Amsterdam
ER  -