@inproceedings{FerreinKallweitScholletal.2015, author = {Ferrein, Alexander and Kallweit, Stephan and Scholl, Ingrid and Reichert, Walter}, title = {Learning to Program Mobile Robots in the ROS Summer School Series}, series = {Proceedings 6th International Conference on Robotics in Education (RiE 15)}, booktitle = {Proceedings 6th International Conference on Robotics in Education (RiE 15)}, pages = {6 S.}, year = {2015}, abstract = {The main objective of our ROS Summer School series is to introduce MA level students to program mobile robots with the Robot Operating System (ROS). ROS is a robot middleware that is used my many research institutions world-wide. Therefore, many state-of-the-art algorithms of mobile robotics are available in ROS and can be deployed very easily. As a basic robot platform we deploy a 1/10 RC cart that is wquipped with an Arduino micro-controller to control the servo motors, and an embedded PC that runs ROS. In two weeks, participants get to learn the basics of mobile robotics hands-on. We describe our teaching concepts and our curriculum and report on the learning success of our students.}, language = {en} } @article{FerreinStrackLakemeyer2006, author = {Ferrein, Alexander and Strack, Andreas and Lakemeyer, Gerhard}, title = {Laser-Based Localization with Sparse Landmarks / Strack, Andreas ; Ferrein, Alexander ; Lakemeyer, Gerhard}, series = {RoboCup 2005: Robot Soccer World Cup IX}, journal = {RoboCup 2005: Robot Soccer World Cup IX}, publisher = {Springer}, address = {Berlin}, isbn = {978-3-540-35437-6}, pages = {569 -- 576}, year = {2006}, language = {en} } @inproceedings{DyllaFerreinLakemeyer2003, author = {Dylla, Frank and Ferrein, Alexander and Lakemeyer, Gerhard}, title = {AllemaniACs 2003 team description}, series = {RoboCup 2003 : Robot Soccer World Cup VII}, booktitle = {RoboCup 2003 : Robot Soccer World Cup VII}, pages = {1 -- 3}, year = {2003}, language = {en} } @article{VorstFerreinLakemeyer2006, author = {Vorst, Phillip and Ferrein, Alexander and Lakemeyer, Gerhard}, title = {AllemaniACs3D team description}, pages = {1 -- 6}, year = {2006}, language = {en} } @article{FerreinSchifferLakemeyer2006, author = {Ferrein, Alexander and Schiffer, Stefan and Lakemeyer, Gerhard}, title = {Qualitative World Models for Soccer Robots / Schiffer, Stefan ; Ferrein, Alexander ; Lakemeyer, Gerhard}, series = {Qualitative constraint calculi : application and integration ; KI 2006, 14 - 19 June 2006, Bremen, Germany ; 29th Annual German Conference on Artificial Intelligence ; workshop / Stefan W{\"o}lfl ... (eds.)}, journal = {Qualitative constraint calculi : application and integration ; KI 2006, 14 - 19 June 2006, Bremen, Germany ; 29th Annual German Conference on Artificial Intelligence ; workshop / Stefan W{\"o}lfl ... (eds.)}, publisher = {Univ.}, address = {Bremen}, isbn = {3-88722-666-6}, pages = {3 -- 14}, year = {2006}, language = {en} } @inproceedings{DuongJungFrotscheretal.2016, author = {Duong, Minh Tuan and Jung, Alexander and Frotscher, Ralf and Staat, Manfred}, title = {A 3D electromechanical FEM-based model for cardiac tissue}, series = {ECCOMAS Congress 2016, VII European Congress on Computational Methods in Applied Sciences and Engineering. Crete Island, Greece, 5-10 June 2016}, booktitle = {ECCOMAS Congress 2016, VII European Congress on Computational Methods in Applied Sciences and Engineering. Crete Island, Greece, 5-10 June 2016}, editor = {Papadrakakis, M.}, pages = {13 S.}, year = {2016}, language = {en} } @article{BungValero2018, author = {Bung, Daniel Bernhard and Valero, Daniel}, title = {Re-aeration on stepped spillways with special consideration of entrained and entrapped air}, series = {Geosciences}, volume = {8}, journal = {Geosciences}, number = {9}, publisher = {MDPI}, address = {Basel}, issn = {2076-3263}, pages = {Article number 333}, year = {2018}, abstract = {As with most high-velocity free-surface flows, stepped spillway flows become self-aerated when the drop height exceeds a critical value. Due to the step-induced macro-roughness, the flow field becomes more turbulent than on a similar smooth-invert chute. For this reason, cascades are oftentimes used as re-aeration structures in wastewater treatment. However, for stepped spillways as flood release structures downstream of deoxygenated reservoirs, gas transfer is also of crucial significance to meet ecological requirements. Prediction of mass transfer velocities becomes challenging, as the flow regime differs from typical previously studied flow conditions. In this paper, detailed air-water flow measurements are conducted on stepped spillway models with different geometry, with the aim to estimate the specific air-water interface. Re-aeration performances are determined by applying the absorption method. In contrast to earlier studies, the aerated water body is considered a continuous mixture up to a level where 75\% air concentration is reached. Above this level, a homogenous surface wave field is considered, which is found to significantly affect the total air-water interface available for mass transfer. Geometrical characteristics of these surface waves are obtained from high-speed camera investigations. The results show that both the mean air concentration and the mean flow velocity have influence on the mass transfer. Finally, an empirical relationship for the mass transfer on stepped spillway models is proposed.}, language = {en} } @inproceedings{KnackstedtEggertHeddieretal.2013, author = {Knackstedt, Ralf and Eggert, Mathias and Heddier, Marcel and Chasin, Friedrich and Becker, J{\"o}rg}, title = {The Relationship of IS and Law - Insights into the German Online Car Registration Case}, series = {ECIS 2013 Completed Research. 18. Proceedings of the 21st European Conference on Information Systems}, booktitle = {ECIS 2013 Completed Research. 18. Proceedings of the 21st European Conference on Information Systems}, pages = {13 S.}, year = {2013}, language = {en} } @inproceedings{OhndorfDachwaldSeboldtetal.2011, author = {Ohndorf, Andreas and Dachwald, Bernd and Seboldt, Wolfgang and Schartner, Karl-Heinz}, title = {Flight times to the heliopause using a combination of solar and radioisotope electric propulsion}, series = {32nd International Electric Propulsion Conference}, booktitle = {32nd International Electric Propulsion Conference}, pages = {1 -- 12}, year = {2011}, abstract = {We investigate the interplanetary flight of a low-thrust space probe to the heliopause,located at a distance of about 200 AU from the Sun. Our goal was to reach this distance within the 25 years postulated by ESA for such a mission (which is less ambitious than the 15-year goal set by NASA). Contrary to solar sail concepts and combinations of allistic and electrically propelled flight legs, we have investigated whether the set flight time limit could also be kept with a combination of solar-electric propulsion and a second, RTG-powered upper stage. The used ion engine type was the RIT-22 for the first stage and the RIT-10 for the second stage. Trajectory optimization was carried out with the low-thrust optimization program InTrance, which implements the method of Evolutionary Neurocontrol,using Artificial Neural Networks for spacecraft steering and Evolutionary Algorithms to optimize the Neural Networks' parameter set. Based on a parameter space study, in which the number of thrust units, the unit's specific impulse, and the relative size of the solar power generator were varied, we have chosen one configuration as reference. The transfer time of this reference configuration was 29.6 years and the fastest one, which is technically more challenging, still required 28.3 years. As all flight times of this parameter study were longer than 25 years, we further shortened the transfer time by applying a launcher-provided hyperbolic excess energy up to 49 km2/s2. The resulting minimal flight time for the reference configuration was then 27.8 years. The following, more precise optimization to a launch with the European Ariane 5 ECA rocket reduced the transfer time to 27.5 years. This is the fastest mission design of our study that is flexible enough to allow a launch every year. The inclusion of a fly-by at Jupiter finally resulted in a flight time of 23.8 years,which is below the set transfer-time limit. However, compared to the 27.5-year transfer,this mission design has a significantly reduced launch window and mission flexibility if the escape direction is restricted to the heliosphere's "nose".}, language = {en} } @article{NguyenDuongTranetal.2012, author = {Nguyen, Nhu Huynh and Duong, Minh Tuan and Tran, Thanh Ngoc and Pham, Phu Tinh and Grottke, O. and Tolba, R. and Staat, Manfred}, title = {Influence of a freeze-thaw cycle on the stress-stretch curves of tissues of porcine abdominal organs}, series = {Journal of Biomechanics}, volume = {45}, journal = {Journal of Biomechanics}, number = {14}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1873-2380}, doi = {10.1016/j.jbiomech.2012.07.008}, pages = {2382 -- 2386}, year = {2012}, abstract = {The paper investigates both fresh porcine spleen and liver and the possible decomposition of these organs under a freeze-thaw cycle. The effect of tissue preservation condition is an important factor which should be taken into account for protracted biomechanical tests. In this work, tension tests were conducted for a large number of tissue specimens from twenty pigs divided into two groups of 10. Concretely, the first group was tested in fresh state; the other one was tested after a freeze-thaw cycle which simulates the conservation conditions before biomechanical experiments. A modified Fung model for isotropic behavior was adopted for the curve fitting of each kind of tissues. Experimental results show strong effects of the realistic freeze-thaw cycle on the capsule of elastin-rich spleen but negligible effects on the liver which virtually contains no elastin. This different behavior could be explained by the autolysis of elastin by elastolytic enzymes during the warmer period after thawing. Realistic biomechanical properties of elastin-rich organs can only be expected if really fresh tissue is tested. The observations are supported by tests of intestines.}, language = {en} }