@inproceedings{LorenzAltherrPelz2020,
  author    = {Lorenz, Imke-Sophie and Altherr, Lena and Pelz, Peter F.},
  title     = {Resilience enhancement of critical infrastructure - graph-theoretical resilience analysis of the water distribution system in the German city of Darmstadt},
  series = {14th WCEAM Proceedings},
  booktitle = {14th WCEAM Proceedings},
  publisher = {Springer},
  address   = {Cham},
  isbn      = {978-3-030-64228-0},
  doi       = {10.1007/978-3-030-64228-0_13},
  pages     = {137 -- 149},
  year      = {2020},
  abstract  = {Water suppliers are faced with the great challenge of achieving high-quality and, at the same time, low-cost water supply. Since climatic and demographic influences will pose further challenges in the future, the resilience enhancement of water distribution systems (WDS), i.e. the enhancement of their capability to withstand and recover from disturbances, has been in particular focus recently. To assess the resilience of WDS, graph-theoretical metrics have been proposed. In this study, a promising approach is first physically derived analytically and then applied to assess the resilience of the WDS for a district in a major German City. The topology based resilience index computed for every consumer node takes into consideration the resistance of the best supply path as well as alternative supply paths. This resistance of a supply path is derived to be the dimensionless pressure loss in the pipes making up the path. The conducted analysis of a present WDS provides insight into the process of actively influencing the resilience of WDS locally and globally by adding pipes. The study shows that especially pipes added close to the reservoirs and main branching points in the WDS result in a high resilience enhancement of the overall WDS.},
  language  = {en}
}
@inproceedings{LopesBungLeandroetal.2015,
  author    = {Lopes, Pedro and Bung, Daniel B. and Leandro, Jorge and Carvalho, Rita F.},
  title     = {The effect of cross-waves in physical stepped spillway models},
  series = {E-proceedings of the 36th IAHR World Congress ; 28 June - 3 July, 2015, The Hague, the Netherlands},
  booktitle = {E-proceedings of the 36th IAHR World Congress ; 28 June - 3 July, 2015, The Hague, the Netherlands},
  organization    = {International Association for Hydro-Environment Engineering and Research},
  pages     = {1 -- 9},
  year      = {2015},
  language  = {en}
}
@inproceedings{LogenHoefkenSchuba2012,
  author    = {Logen, Steffen and H{\"o}fken, Hans and Schuba, Marko},
  title     = {Simplifying RAM Forensics : A GUI and Extensions for the Volatility Framework},
  series = {2012 Seventh International Conference on Availability, Reliability and Security (ARES), 20-24 August 2012, Prague, Czech Republic},
  booktitle = {2012 Seventh International Conference on Availability, Reliability and Security (ARES), 20-24 August 2012, Prague, Czech Republic},
  publisher = {IEEE},
  address   = {New York},
  isbn      = {978-1-4673-2244-7},
  doi       = {10.1109/ARES.2012.12},
  pages     = {620 -- 624},
  year      = {2012},
  abstract  = {The Volatility Framework is a collection of tools for the analysis of computer RAM. The framework offers a multitude of analysis options and is used by many investigators worldwide. Volatility currently comes with a command line interface only, which might be a hinderer for some investigators to use the tool. In this paper we present a GUI and extensions for the Volatility Framework, which on the one hand simplify the usage of the tool and on the other hand offer additional functionality like storage of results in a database, shortcuts for long Volatility Framework command sequences, and entirely new commands based on correlation of data stored in the database.},
  language  = {en}
}
@inproceedings{LoebSchartnerDachwaldetal.2007,
  author    = {Loeb, Horst Wolfgang and Schartner, Karl-Heinz and Dachwald, Bernd and Seboldt, Wolfgang},
  title     = {SEP-Sample return from a main belt asteroid},
  series = {30th International Electric Propulsion Conference},
  booktitle = {30th International Electric Propulsion Conference},
  pages     = {1 -- 11},
  year      = {2007},
  abstract  = {By DLR-contact, sample return missions to the large main-belt asteroid "19, Fortuna" have been studied. The mission scenario has been based on three ion thrusters of the RIT-22 model, which is presently under space qualification, and on solar arrays equipped with triple-junction GaAs solar cells. After having designed the spacecraft, the orbit-to-orbit trajectories for both, a one-way SEP mission with a chemical sample return and an all-SEP return mission, have been optimized using a combination of artificial neural networks with evolutionary algorithms. Additionally, body-to-body trajectories have been investigated within a launch period between 2012 and 2015. For orbit-to-orbit calculation, the launch masses of the hybrid mission and of the all-SEP mission resulted in 2.05 tons and 1.56 tons, respectively, including a scientific payload of 246 kg. For the related transfer durations 4.14 yrs and 4.62 yrs were obtained. Finally, a comparison between the mission scenarios based on SEP and on NEP have been carried out favouring clearly SEP.},
  language  = {en}
}
@inproceedings{LoebSchartnerSeboldtetal.2006,
  author    = {Loeb, Horst W. and Schartner, Karl-Heinz and Seboldt, Wolfgang and Dachwald, Bernd and Streppel, Joern and Meusemann, Hans and Sch{\"u}lke, Peter},
  title     = {SEP for a lander mission to the jovian moon europa},
  series = {57th International Astronautical Congress},
  booktitle = {57th International Astronautical Congress},
  doi       = {10.2514/6.IAC-06-C4.4.04},
  pages     = {1 -- 12},
  year      = {2006},
  abstract  = {Under DLR-contract, Giessen University and DLR Cologne are studying solar-electric propulsion missions (SEP) to the outer regions of the solar system. The most challenging reference mission concerns the transport of a 1.35-tons chemical lander spacecraft into an 80-RJ circular orbit around Jupiter, which would enable to place a 375 kg lander with 50 kg of scientific instruments on the surface of the icy moon "Europa". Thorough analyses show that the best solution in terms of SEP launch mass times thrusting time would be a two-stage EP module and a triple-junction solar array with concentrators which would be deployed step by step. Mission performance optimizations suggest to propel the spacecraft in the first EP stage by 6 gridded ion thrusters, running at 4.0 kV of beam voltage, which would save launch mass, and in the second stage by 4 thrusters with 1.25 to 1.5 kV of positive high voltage saving thrusting time. In this way, the launch mass of the spacecraft would be kept within 5.3 tons. Without a launcher's C3 and interplanetary gravity assists, Jupiter might be reached within about 4 yrs. The spiraling-down into the parking orbit would need another 1.8 yrs. This "large mission" can be scaled down to a smaller one, e.g., by halving all masses, the solar array power, and the number of thrusters. Due to their reliability, long lifetime and easy control, RIT-22 engines have been chosen for mission analysis. Based on precise tests, the thruster performance has been modeled.},
  language  = {en}
}
@inproceedings{LoebSchartnerDachwaldetal.2011,
  author    = {Loeb, Horst W. and Schartner, Karl-Heinz and Dachwald, Bernd and Ohndorf, Andreas and Seboldt, Wolfgang},
  title     = {An Interstellar - Heliopause mission using a combination of solar/radioisotope electric propulsion},
  series = {Presented at the 32nd International Electric Propulsion Conference},
  booktitle = {Presented at the 32nd International Electric Propulsion Conference},
  pages     = {1 -- 7},
  year      = {2011},
  abstract  = {There is common agreement within the scientific community that in order to understand our local galactic environment it will be necessary to send a spacecraft into the region beyond the solar wind termination shock. Considering distances of 200 AU for a new mission, one needs a spacecraft 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.},
  language  = {en}
}
@inproceedings{LoPiparoKernMazzetti2012,
  author    = {Lo Piparo, G. B. and Kern, Alexander and Mazzetti, C.},
  title     = {Some masterpoints about risk due to lightning},
  series = {International Conference on Lightning Protection (ICLP) : 2 - 7 Sept. 2012, Vienna},
  booktitle = {International Conference on Lightning Protection (ICLP) : 2 - 7 Sept. 2012, Vienna},
  publisher = {IEEE},
  address   = {Piscataway, NJ},
  organization    = {International Conference on Lightning Protection <2012, Wien>},
  isbn      = {978-1-4673-1896-9 (E-Book) ; 978-1-4673-1898-3 (Print)},
  pages     = {1 -- 6},
  year      = {2012},
  language  = {en}
}
@inproceedings{LindnerKolbRingbeck2008,
  author    = {Lindner, Marvin and Kolb, Andreas and Ringbeck, Thorsten},
  title     = {New insights into the calibration of ToF-sensors},
  series = {2008 IEEE Computer Society Conference on Computer Vision and Pattern Recognition workshops : Anchorage, AK, 23 - 28 June 2008},
  booktitle = {2008 IEEE Computer Society Conference on Computer Vision and Pattern Recognition workshops : Anchorage, AK, 23 - 28 June 2008},
  publisher = {IEEE Service Center},
  address   = {Piscataway, NJ},
  isbn      = {978-1-4244-2339-2},
  pages     = {1 -- 5},
  year      = {2008},
  abstract  = {Time-of-flight (ToF) sensors have become an alternative to conventional distance sensing techniques like laser scanners or image based stereo. ToF sensors provide full range distance information at high frame-rates and thus have a significant impact onto current research in areas like online object recognition, collision prevention or scene reconstruction. However, ToF cameras like the photonic mixer device (PMD) still exhibit a number of challenges regarding static and dynamic effects, e.g. systematic distance errors and motion artefacts, respectively. Sensor calibration techniques reducing static system errors have been proposed and show promising results. However, current calibration techniques in general need a large set of reference data in order to determine the corresponding parameters for the calibration model. This paper introduces a new calibration approach which combines different demodulation techniques for the ToF- camera 's reference signal. Examples show, that the resulting combined demodulation technique yields improved distance values based on only two required reference data sets.},
  language  = {en}
}
@inproceedings{LindenlaufHoefkenSchuba2015,
  author    = {Lindenlauf, Simon and H{\"o}fken, Hans-Wilhelm and Schuba, Marko},
  title     = {Cold Boot Attacks on DDR2 and DDR3 SDRAM},
  series = {10th International Conference on Availability, Reliability and Security (ARES) 2015},
  booktitle = {10th International Conference on Availability, Reliability and Security (ARES) 2015},
  doi       = {10.1109/ARES.2015.28},
  pages     = {287 -- 292},
  year      = {2015},
  language  = {en}
}
@inproceedings{LindemannRunge1998,
  author    = {Lindemann, Markus and Runge, Alexander},
  title     = {Electronic contracting within the reference model for electronic markets},
  series = {Proceedings of the Sixth European Conference on Information Systems, ECIS 1998, Aix-en-Provence, France, June 4-6, 1998 / Walter Baets (ed.)},
  booktitle = {Proceedings of the Sixth European Conference on Information Systems, ECIS 1998, Aix-en-Provence, France, June 4-6, 1998 / Walter Baets (ed.)},
  publisher = {Euro-Arab Management School},
  isbn      = {849238333X},
  pages     = {44 -- 59},
  year      = {1998},
  language  = {en}
}
@inproceedings{LimpertSchifferFerrein2015,
  author    = {Limpert, Nicolas and Schiffer, Stefan and Ferrein, Alexander},
  title     = {A Local Planner for Ackermann-Driven Vehicles in ROS SBPL},
  series = {Proceedings of the International Conference on Pattern Recognition Association of South Africa and Robotics and Mechatronics (PRASA-RobMech), 2015},
  booktitle = {Proceedings of the International Conference on Pattern Recognition Association of South Africa and Robotics and Mechatronics (PRASA-RobMech), 2015},
  doi       = {10.1109/RoboMech.2015.7359518},
  pages     = {172 -- 177},
  year      = {2015},
  language  = {en}
}
@inproceedings{LenzWolf2014,
  author    = {Lenz, Laura L. and Wolf, Martin},
  title     = {Economic evaluation of serious games with the comparative assessment framework COSEGA},
  series = {The shift from teaching to learning : individual, collective and organizational learning through gaming simulation ; proceedings of the 45th conference of the International Simulation and Gaming Association, Dornbirn 2014},
  booktitle = {The shift from teaching to learning : individual, collective and organizational learning through gaming simulation ; proceedings of the 45th conference of the International Simulation and Gaming Association, Dornbirn 2014},
  editor    = {Kritz, Willy Christian},
  publisher = {Bertelsmann},
  address   = {[Bielefeld]},
  isbn      = {978-3-7639-5422-3},
  pages     = {374 -- 386},
  year      = {2014},
  language  = {en}
}
@inproceedings{LeiseSimonAltherr2020,
  author    = {Leise, Philipp and Simon, Nicolai and Altherr, Lena},
  title     = {Comparison of Piecewise Linearization Techniques to Model Electric Motor Efficiency Maps: A Computational Study},
  series = {Operations Research Proceedings 2019},
  booktitle = {Operations Research Proceedings 2019},
  publisher = {Springer},
  address   = {Cham},
  isbn      = {978-3-030-48439-2},
  doi       = {10.1007/978-3-030-48439-2_55},
  pages     = {457 -- 463},
  year      = {2020},
  abstract  = {To maximize the travel distances of battery electric vehicles such as cars or buses for a given amount of stored energy, their powertrains are optimized energetically. One key part within optimization models for electric powertrains is the efficiency map of the electric motor. The underlying function is usually highly nonlinear and nonconvex and leads to major challenges within a global optimization process. To enable faster solution times, one possibility is the usage of piecewise linearization techniques to approximate the nonlinear efficiency map with linear constraints. Therefore, we evaluate the influence of different piecewise linearization modeling techniques on the overall solution process and compare the solution time and accuracy for methods with and without explicitly used binary variables.},
  language  = {en}
}
@inproceedings{LeiseBreuerAltherretal.2020,
  author    = {Leise, Philipp and Breuer, Tim and Altherr, Lena and Pelz, Peter F.},
  title     = {Development, validation and assessment of a resilient pumping system},
  series = {Proceedings of the Joint International Resilience Conference, JIRC2020},
  booktitle = {Proceedings of the Joint International Resilience Conference, JIRC2020},
  isbn      = {978-90-365-5095-6},
  pages     = {97 -- 100},
  year      = {2020},
  abstract  = {The development of resilient technical systems is a challenging task, as the system should adapt automatically to unknown disturbances and component failures. To evaluate different approaches for deriving resilient technical system designs, we developed a modular test rig that is based on a pumping system. On the basis of this example system, we present metrics to quantify resilience and an algorithmic approach to improve resilience. This approach enables the pumping system to automatically react on unknown disturbances and to reduce the impact of component failures. In this case, the system is able to automatically adapt its topology by activating additional valves. This enables the system to still reach a minimum performance, even in case of failures. Furthermore, timedependent disturbances are evaluated continuously, deviations from the original state are automatically detected and anticipated in the future. This allows to reduce the impact of future disturbances and leads to a more resilient system behaviour.},
  language  = {en}
}
@inproceedings{LeiseAltherrPelz2018,
  author    = {Leise, Philipp and Altherr, Lena and Pelz, Peter F.},
  title     = {Technical Operations Research (TOR) - Algorithms, not Engineers, Design Optimal Energy Efficient and Resilient Cooling Systems},
  series = {FAN2018 - Proceedings of the International Conference on Fan Noise, Aerodynamics, Applications and Systems},
  booktitle = {FAN2018 - Proceedings of the International Conference on Fan Noise, Aerodynamics, Applications and Systems},
  pages     = {1 -- 12},
  year      = {2018},
  abstract  = {The overall energy efficiency of ventilation systems can be improved by considering not only single components, but by considering as well the interplay between every part of the system. With the help of the method "TOR" ("Technical Operations Research"), which was developed at the Chair of Fluid Systems at TU Darmstadt, it is possible to improve the energy efficiency of the whole system by considering all possible design choices programmatically. We show the ability of this systematic design approach with a ventilation system for buildings as a use case example. Based on a Mixed-Integer Nonlinear Program (MINLP) we model the ventilation system. We use binary variables to model the selection of different pipe diameters. Multiple fans are model with the help of scaling laws. The whole system is represented by a graph, where the edges represent the pipes and fans and the nodes represents the source of air for cooling and the sinks, that have to be cooled. At the beginning, the human designer chooses a construction kit of different suitable fans and pipes of different diameters and different load cases. These boundary conditions define a variety of different possible system topologies. It is not possible to consider all topologies by hand. With the help of state of the art solvers, on the other side, it is possible to solve this MINLP. Next to this, we also consider the effects of malfunctions in different components. Therefore, we show a first approach to measure the resilience of the shown example use case. Further, we compare the conventional approach with designs that are more resilient. These more resilient designs are derived by extending the before mentioned model with further constraints, that consider explicitly the resilience of the overall system. We show that it is possible to design resilient systems with this method already in the early design stage and compare the energy efficiency and resilience of these different system designs.},
  language  = {en}
}
@inproceedings{LeiseAltherr2018,
  author    = {Leise, Philipp and Altherr, Lena},
  title     = {Optimizing the design and control of decentralized water supply systems - a case-study of a hotel building},
  series = {EngOpt 2018 Proceedings of the 6th International Conference on Engineering Optimization},
  booktitle = {EngOpt 2018 Proceedings of the 6th International Conference on Engineering Optimization},
  publisher = {Springer},
  address   = {Cham},
  isbn      = {978-3-319-97773-7},
  doi       = {10.1007/978-3-319-97773-7_107},
  pages     = {1241 -- 1252},
  year      = {2018},
  abstract  = {To increase pressure to supply all floors of high buildings with water, booster stations, normally consisting of several parallel pumps in the basement, are used. In this work, we demonstrate the potential of a decentralized pump topology regarding energy savings in water supply systems of skyscrapers. We present an approach, based on Mixed-Integer Nonlinear Programming, that allows to choose an optimal network topology and optimal pumps from a predefined construction kit comprising different pump types. Using domain-specific scaling laws and Latin Hypercube Sampling, we generate different input sets of pump types and compare their impact on the efficiency and cost of the total system design. As a realistic application example, we consider a hotel building with 325 rooms, 12 floors and up to four pressure zones.},
  language  = {en}
}
@inproceedings{LeingartnerMaurerSteinbaueretal.2013,
  author    = {Leingartner, Max and Maurer, Johannes and Steinbauer, Gerald and Ferrein, Alexander},
  title     = {Evaluation of sensors and mapping approaches for disasters in tunnels},
  series = {IEEE International Symposium on Safety, Security, and Rescue Robotics : SSRR : 21-26 Oct. 2013, Linkoping, Sweden},
  booktitle = {IEEE International Symposium on Safety, Security, and Rescue Robotics : SSRR : 21-26 Oct. 2013, Linkoping, Sweden},
  organization    = {Institute of Electrical and Electronics Engineers},
  isbn      = {978-1-4799-0879-0},
  pages     = {1 -- 7},
  year      = {2013},
  language  = {en}
}
@inproceedings{LeichtScholtenSteuerDankertBouffier2016,
  author    = {Leicht-Scholten, Carmen and Steuer-Dankert, Linda and Bouffier, Anna},
  title     = {Facing Future Challenges: Building Engineers for Tomorrow},
  series = {Conference proceedings : new perspectives in science education : 5th Conference edition, Florence, Italy, 17-18 March 2016},
  booktitle = {Conference proceedings : new perspectives in science education : 5th Conference edition, Florence, Italy, 17-18 March 2016},
  isbn      = {978-886292-705-5},
  pages     = {32 -- 37},
  year      = {2016},
  abstract  = {Future engineers are increasingly confronted with the so-called Megatrends which are the big social challenges society has to cope with. These Megatrends, such as "Silver Society", "Globalization", "Mobility" and "Female Shift" require an application-oriented perspective on Diversity especially in the engineering field. Therefore, it is necessary to enable future engineers not only to look at the technical perspectives of a problem, but also to be able to see the related questions within societies they are developing their artefacts for. The aim of teaching engineering should be to prepare engineers for these requirements and to draw attention to the diverse needs in a globalized world. Bringing together technical knowledge and social competences which go beyond a mere training of the so-called "soft skills", is a new approach followed at RWTH Aachen University, one of the leading technical universities in Germany. RWTH Aachen University has established the bridging professorship "Gender and Diversity in Engineering" (GDI) which educates engineers with an interdisciplinary approach to expand engineering limits. In the frame of a sustainable teaching concept the research group under the leadership of Prof. Carmen Leicht-Scholten has developed an approach which imparts a supplication-specific Gender and Diversity expertise to engineers. In workshops students gain theoretical knowledge about Gender and Diversity and learn how to transfer their knowledge in their special field of study and later work. To substantiate this, the course participants have to solve case studies from real life. The cases which are developed in collaboration with non-profit organizations and enterprises from economy rise the students to challenges which are inspired by professional life. Evaluation shows the success of this approach as well as an increasing demand for such teaching formats.},
  language  = {en}
}
@inproceedings{LatzkeAlexopoulosKronhardtetal.2015,
  author    = {Latzke, Markus and Alexopoulos, Spiros and Kronhardt, Valentina and Rend{\´o}n, Carlos and Sattler, Johannes, Christoph},
  title     = {Comparison of Potential Sites in China for Erecting a Hybrid Solar Tower Power Plant with Air Receiver},
  series = {Energy Procedia},
  booktitle = {Energy Procedia},
  issn      = {1876-6102},
  doi       = {10.1016/j.egypro.2015.03.142},
  pages     = {1327 -- 1334},
  year      = {2015},
  language  = {en}
}
@inproceedings{LandAGligorevic2004,
  author    = {Land, Ingmar and A., Peter and Gligorevic, Snjezana},
  title     = {Computation of symbol-wise mutual information in transmission systems with logAPP decoders and application to EXIT charts},
  series = {5th International ITG Conference on Source and Channel Coding (SCC) : January 14 - 16, 2004, Erlangen ; conference record. (ITG-Fachbericht ; 181)},
  booktitle = {5th International ITG Conference on Source and Channel Coding (SCC) : January 14 - 16, 2004, Erlangen ; conference record. (ITG-Fachbericht ; 181)},
  publisher = {VDE-Verl.},
  address   = {Berlin [u.a.]},
  organization    = {International Conference Source and Channel Coding <5, 2004, Erlangen>},
  isbn      = {3-8007-2802-8},
  pages     = {195 -- 202},
  year      = {2004},
  language  = {en}
}