@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{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{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{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{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{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{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{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{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{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} }