@inproceedings{Andorfer2007, author = {Andorfer, Johann}, title = {Parallelisierung und verteiltes Rechnen - Chancen f{\"u}r die Langzeitsimulation}, year = {2007}, abstract = {Dipl.Ing. Johann Andorfer , Tandler.com GmbH, Buch a. Erlbach. Abstract zum 1. Aachener Softwaretag in der Wasserwirtschaft <1,2007, Aachen>. 2 S. (S. 136-137) Eine nachhaltige Sicherung der Funktionalit{\"a}t und der {\"o}kologischen Vertr{\"a}glichkeit eines mittleren bis großen Kanalnetzes erfordert eine umfassende und detaillierte Modellierung in Raum und Zeit. Um den in den Richtlinien geforderten statistischen Anforderungen gerecht zu werden und die j{\"a}hrlichen H{\"a}ufigkeiten, Mengen und Zeitr{\"a}ume der Belastungen erwartungstreu absch{\"a}tzen zu k{\"o}nnen, ist es zielf{\"u}hrend und notwendig, lange Zeitr{\"a}ume und die Gesamtheit der Einzugsgebiete m{\"o}glichst detailliert zu betrachten. Die hydraulische Funktionalit{\"a}t und Sicherheit soll meistens mit Hilfe zeitsymmetrischer (hydrodynamischer) Verfahren nur durch Betrachtung von Modellregen, allenfalls Regenserien, sichergestellt werden. F{\"u}r die Absch{\"a}tzung der j{\"a}hrlich zu erwartenden Emissionen in unsere nat{\"u}rlichen Gew{\"a}sser mit ihren Mengen, Frequenzen und Dauern werden normalerweise Langzeitsimulationen nat{\"u}rlicher Regenreihen {\"u}ber m{\"o}glichst große Zeitr{\"a}ume mit zeitasymmetrischen (hydrologischen) Verfahren durchgef{\"u}hrt. Die betrachteten Kanalnetze werden zumeist vereinfacht (Grobnetze), um die Rechenzeiten ertr{\"a}glicher zu gestalten. W{\"u}nschenswert w{\"a}re jedoch eine allen Anforderungen gerecht werdende wirklichkeitsnahe Modellierung des gesamten Kanalnetzes in all seinen Details, Vermaschungen und Wechselwirkungen (Feinnetz) und dessen zeitsymmetrische und damit verl{\"a}ssliche Simulation mit langj{\"a}hrigen Regenreihen. Bereits vor 15 Jahren wurde im Hause Tandler begonnen, die Berechnungssoftware durch Parallelisierung auf symmetrische Multiprozessortechnologien auszurichten. In neuerer Zeit h{\"a}lt diese Technik durch die Mehrkernprozessoren in normalen Notebooks und PCs Einzug in die Ingenieurb{\"u}ros und Abwasserbetriebe und sorgt schon f{\"u}r wesentliche Einsparungen an Rechenzeit. Doch erst durch die Kombination der Parallelisierung mit dem Prinzip des verteilten Rechnens (d.h. die Einbeziehung mehrerer PCs eines Netzwerkes in die Berechnung) erh{\"a}lt man die Chance ausreichend Rechenkapazit{\"a}t zur Verf{\"u}gung zu stellen, um nicht nur eine einzelne Langzeitsimulation eines Feinnetzes durchzuf{\"u}hren, sondern sogar mehrere Sanierungsalternativen zu {\"u}berpr{\"u}fen. Die zukunftsweisenden Arbeiten von Dipl. Math. R. Tandler auf diesem Gebiet sind Thema dieses Vortrags.}, subject = {Kanalisation}, language = {de} } @inproceedings{BragardKoellenspergerDeDoncker2007, author = {Bragard, Michael and K{\"o}llensperger, P. and De Doncker, R. W.}, title = {Der Internally Commutated Thyristor (ICT) : ein neuartiger GCT mit integrierter Ausschalteinheit}, series = {"Nowoczesne urządzenia zasilające w energetyce" : X międzynarodowa konferencja naukowo techniczna, Zakopane, 14-16 marca 2007 r. : materiały konferencyjne}, booktitle = {"Nowoczesne urządzenia zasilające w energetyce" : X międzynarodowa konferencja naukowo techniczna, Zakopane, 14-16 marca 2007 r. : materiały konferencyjne}, editor = {Dmowski, Antoni}, publisher = {APS Energia}, address = {Warszawa}, isbn = {83-918709-7-9}, pages = {7.1 -- 7.9}, year = {2007}, language = {de} } @inproceedings{BrandesGligorevicSchnelletal.2007, author = {Brandes, Sinja and Gligorevic, Snjezana and Schnell, Michael and Rokitansky, Carl-Herbert and Ehammer, Max and Gr{\"a}upl, Thomas and Schlereth, Armin and Rihacek, Christoph}, title = {Final assessment of the B-VHF overlay concept}, series = {IEEE Aerospace Conference : 3-10 March 2007, Big Sky, Mont.}, booktitle = {IEEE Aerospace Conference : 3-10 March 2007, Big Sky, Mont.}, organization = {Institute of Electrical and Electronics Engineers}, isbn = {1-4244-0525-4}, pages = {1 -- 18}, year = {2007}, language = {en} } @inproceedings{BreitbachAlexopoulosHoffschmidt2007, author = {Breitbach, Gerd and Alexopoulos, Spiros and Hoffschmidt, Bernhard}, title = {Fluid flow in porous ceramic multichannel crossflower filter modules}, publisher = {COMSOL Inc.}, address = {Burlington, Mass.}, pages = {5 S.}, year = {2007}, language = {en} } @inproceedings{BudaJozenfiniWollert2007, author = {Buda, Aurel and Jozenfini, B. and Wollert, J{\"o}rg}, title = {Mobile ad-hoc Network for home automation based on ZigBee application framework}, series = {1st European ZigBee Developer's Conference : June 18 - 20, 2007, Munich, Germany}, booktitle = {1st European ZigBee Developer's Conference : June 18 - 20, 2007, Munich, Germany}, publisher = {Design \& Elektronik}, address = {Poing}, organization = {European ZigBee Developer's Conference <1, 2007, M{\"u}nchen>}, pages = {1 -- 5}, year = {2007}, language = {en} } @inproceedings{BudaVredalWollert2007, author = {Buda, Aurel and Vredal, Andreas and Wollert, J{\"o}rg}, title = {Einfache Integration von funkgest{\"u}tzten Kommunikationssystemen in der Automation}, series = {Wireless Technologies : 9. Kongress, 18. - 19. September 2007, Stuttgart ; von der Technologie zur Anwendung}, booktitle = {Wireless Technologies : 9. Kongress, 18. - 19. September 2007, Stuttgart ; von der Technologie zur Anwendung}, editor = {Wollert, J{\"o}rg}, publisher = {Aka}, address = {Berlin}, organization = {Wireless-Technologies-Kongress <9, 2007, Stuttgart>}, isbn = {978-3-89838-084-3}, pages = {189 -- 198}, year = {2007}, language = {de} } @inproceedings{Butenweg2007, author = {Butenweg, Christoph}, title = {Nachweis der Erdbebensicherheit von Silos aus Stahl unter Erdbebenbelastung}, series = {D-A-CH Tagung 2007 : Aktuelle Themen des Erdbebeningenieurwesens und der Baudynamik ; 27. und 28. September 2007, arsenal research, TECHbase Vienna}, booktitle = {D-A-CH Tagung 2007 : Aktuelle Themen des Erdbebeningenieurwesens und der Baudynamik ; 27. und 28. September 2007, arsenal research, TECHbase Vienna}, organization = {D-A-CH Tagung <2007, Wien>}, pages = {1 -- 14}, year = {2007}, language = {de} } @inproceedings{Dachwald2007, author = {Dachwald, Bernd}, title = {Low-Thrust Mission Analysis and Global Trajectory Optimization Using Evolutionary Neurocontrol: New Results}, series = {European Workshop on Space Mission Analysis ESA/ESOC, Darmstadt, Germany 10 { 12 Dec 2007}, booktitle = {European Workshop on Space Mission Analysis ESA/ESOC, Darmstadt, Germany 10 { 12 Dec 2007}, year = {2007}, abstract = {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}, language = {en} } @inproceedings{DachwaldKahleWie2007, author = {Dachwald, Bernd and Kahle, Ralph and Wie, Bong}, title = {Head-on impact deflection of NEAs: a case study for 99942 Apophis}, series = {Planetary Defense Conference 2007}, booktitle = {Planetary Defense Conference 2007}, pages = {1 -- 12}, year = {2007}, abstract = {Near-Earth asteroid (NEA) 99942 Apophis provides a typical example for the evolution of asteroid orbits that lead to Earth-impacts after a close Earth-encounter that results in a resonant return. Apophis will have a close Earth-encounter in 2029 with potential very close subsequent Earth-encounters (or even an impact) in 2036 or later, depending on whether it passes through one of several less than 1 km-sized gravitational keyholes during its 2029-encounter. A pre-2029 kinetic impact is a very favorable option to nudge the asteroid out of a keyhole. The highest impact velocity and thus deflection can be achieved from a trajectory that is retrograde to Apophis orbit. With a chemical or electric propulsion system, however, many gravity assists and thus a long time is required to achieve this. We show in this paper that the solar sail might be the better propulsion system for such a mission: a solar sail Kinetic Energy Impactor (KEI) spacecraft could impact Apophis from a retrograde trajectory with a very high relative velocity (75-80 km/s) during one of its perihelion passages. The spacecraft consists of a 160 m × 160 m, 168 kg solar sail assembly and a 150 kg impactor. Although conventional spacecraft can also achieve the required minimum deflection of 1 km for this approx. 320 m-sized object from a prograde trajectory, our solar sail KEI concept also allows the deflection of larger objects. For a launch in 2020, we also show that, even after Apophis has flown through one of the gravitational keyholes in 2029, the solar sail KEI concept is still feasible to prevent Apophis from impacting the Earth, but many KEIs would be required for consecutive impacts to increase the total Earth-miss distance to a safe value}, language = {en} } @inproceedings{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} }