@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{LeiMulchandaniChenetal.2006, author = {Lei, Yu and Mulchandani, Priti and Chen, Wilfred and Mulchandani, Ashok}, title = {Biosensor for direct determination of fenitrothion and EPN using recombinant Pseudomonas putida JS444 with surface expressed organophosphorus hydrolase. 1. modified clark oxygen electrode}, url = {http://nbn-resolving.de/urn:nbn:de:hbz:a96-opus-1573}, year = {2006}, abstract = {This paper reports a first microbial biosensor for rapid and cost-effective determination of organophosphorus pesticides fenitrothion and EPN. The biosensor consisted of recombinant PNP-degrading/oxidizing bacteria Pseudomonas putida JS444 anchoring and displaying organophosphorus hydrolase (OPH) on its cell surface as biological sensing element and a dissolved oxygen electrode as the transducer. Surfaceexpressed OPH catalyzed the hydrolysis of fenitrothion and EPN to release 3-methyl-4-nitrophenol and p-nitrophenol, respectively, which were oxidized by the enzymatic machinery of Pseudomonas putida JS444 to carbon dioxide while consuming oxygen, which was measured and correlated to the concentration of organophosphates. Under the optimum operating conditions, the biosensor was able to measure as low as 277 ppb of fenitrothion and 1.6 ppm of EPN without interference from phenolic compounds and other commonly used pesticides such as carbamate pesticides, triazine herbicides and organophosphate pesticides without nitrophenyl substituent. The applicability of the biosensor to lake water was also demonstrated.}, subject = {Biosensor}, 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{LangohrBungCrookston2022, author = {Langohr, Philipp and Bung, Daniel Bernhard and Crookston, Brian M.}, title = {Hybrid investigation of labyrinth weirs: Discharge capacity and energy dissipation}, series = {Proceedings of the 39th IAHR World Congress}, booktitle = {Proceedings of the 39th IAHR World Congress}, editor = {Ortega-S{\´a}nchez, Miguel}, publisher = {International Association for Hydro-Environment Engineering and Research (IAHR)}, address = {Madrid}, isbn = {978-90-832612-1-8}, issn = {2521-7119 (print)}, doi = {10.3850/IAHR-39WC252171192022738}, pages = {2313 -- 2318}, year = {2022}, abstract = {The replacement of existing spillway crests or gates with labyrinth weirs is a proven techno-economical means to increase the discharge capacity when rehabilitating existing structures. However, additional information is needed regarding energy dissipation of such weirs, since due to the folded weir crest, a three-dimensional flow field is generated, yielding more complex overflow and energy dissipation processes. In this study, CFD simulations of labyrinth weirs were conducted 1) to analyze the discharge coefficients for different discharges to compare the Cd values to literature data and 2) to analyze and improve energy dissipation downstream of the structure. All tests were performed for a structure at laboratory scale with a height of approx. P = 30.5 cm, a ratio of the total crest length to the total width of 4.7, a sidewall angle of 10° and a quarter-round weir crest shape. Tested headwater ratios were 0.089 ≤ HT/P ≤ 0.817. For numerical simulations, FLOW-3D Hydro was employed, solving the RANS equations with use of finite-volume method and RNG k-ε turbulence closure. In terms of discharge capacity, results were compared to data from physical model tests performed at the Utah Water Research Laboratory (Utah State University), emphasizing higher discharge coefficients from CFD than from the physical model. For upstream heads, some discrepancy in the range of ± 1 cm between literature, CFD and physical model tests was identified with a discussion regarding differences included in the manuscript. For downstream energy dissipation, variable tailwater depths were considered to analyze the formation and sweep-out of a hydraulic jump. It was found that even for high discharges, relatively low downstream Froude numbers were obtained due to high energy dissipation involved by the three-dimensional flow between the sidewalls. The effects of some additional energy dissipation devices, e.g. baffle blocks or end sills, were also analyzed. End sills were found to be non-effective. However, baffle blocks with different locations may improve energy dissipation downstream of labyrinth weirs.}, 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} } @inproceedings{LahrsKrisamHerrmann2023, author = {Lahrs, Lennart and Krisam, Pierre and Herrmann, Ulf}, title = {Envisioning a collaborative energy system planning platform for the energy transition at the district level}, series = {ECOS 2023. The 36th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems}, booktitle = {ECOS 2023. The 36th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems}, publisher = {Procedings of ECOS 2023}, doi = {10.52202/069564-0284}, pages = {3163 -- 3170}, year = {2023}, abstract = {Residential and commercial buildings account for more than one-third of global energy-related greenhouse gas emissions. Integrated multi-energy systems at the district level are a promising way to reduce greenhouse gas emissions by exploiting economies of scale and synergies between energy sources. Planning district energy systems comes with many challenges in an ever-changing environment. Computational modelling established itself as the state-of-the-art method for district energy system planning. Unfortunately, it is still cumbersome to combine standalone models to generate insights that surpass their original purpose. Ideally, planning processes could be solved by using modular tools that easily incorporate the variety of competing and complementing computational models. Our contribution is a vision for a collaborative development and application platform for multi-energy system planning tools at the district level. We present challenges of district energy system planning identified in the literature and evaluate whether this platform can help to overcome these challenges. Further, we propose a toolkit that represents the core technical elements of the platform. Lastly, we discuss community management and its relevance for the success of projects with collaboration and knowledge sharing at their core.}, language = {en} } @inproceedings{KueppersSchubaNeugebaueretal.2023, author = {K{\"u}ppers, Malte and Schuba, Marko and Neugebauer, Georg and H{\"o}ner, Tim and Hack, Sacha}, title = {Security analysis of the KNX smart building protocol}, series = {ARES '23: Proceedings of the 18th International Conference on Availability, Reliability and Security}, booktitle = {ARES '23: Proceedings of the 18th International Conference on Availability, Reliability and Security}, publisher = {ACM}, doi = {10.1145/3600160.3605167}, pages = {1 -- 7}, year = {2023}, abstract = {KNX is a protocol for smart building automation, e.g., for automated heating, air conditioning, or lighting. This paper analyses and evaluates state-of-the-art KNX devices from manufacturers Merten, Gira and Siemens with respect to security. On the one hand, it is investigated if publicly known vulnerabilities like insecure storage of passwords in software, unencrypted communication, or denialof-service attacks, can be reproduced in new devices. On the other hand, the security is analyzed in general, leading to the discovery of a previously unknown and high risk vulnerability related to so-called BCU (authentication) keys.}, language = {en} } @inproceedings{KoetterDeckerDetzleretal.2012, author = {K{\"o}tter, Jens and Decker, Stefan and Detzler, Raphael and Sch{\"a}fer, Jochen and Schmitz, Mark and Herrmann, Ulf}, title = {Cost Reduction of Solar Fields with HelioTrough Collector}, publisher = {FLAGSOL}, address = {K{\"o}ln}, pages = {9 S. : Ill., graph. Darst.}, year = {2012}, language = {en} } @inproceedings{KoenigWolf2016, author = {K{\"o}nig, Johannes Alexander and Wolf, Martin}, title = {The pyramid assessment framework for 'competence developing games'}, series = {Communications in Computer and Information Science}, volume = {618}, booktitle = {Communications in Computer and Information Science}, editor = {Stephanidis, C.}, publisher = {Springer}, isbn = {978-331940541-4}, issn = {1865-0929}, doi = {10.1007/978-3-319-40542-1_37}, pages = {232 -- 237}, year = {2016}, language = {en} } @inproceedings{KoenigWolf2016, author = {K{\"o}nig, Johannes Alexander and Wolf, Martin}, title = {A new definition of competence developing games - and a framework to assess them}, series = {ACHI 2016 : The Ninth International Conference on Advances in Computer-Human Interactions}, booktitle = {ACHI 2016 : The Ninth International Conference on Advances in Computer-Human Interactions}, isbn = {978-1-61208-468-8}, pages = {95 -- 97}, year = {2016}, abstract = {There are different types of games that try to make use of the motivation of a gaming situation in learning contexts. This paper introduces the new terminology 'Competence Developing Game' (CDG) as an umbrella term for all games with this intention. Based on this new terminology, an assessment framework has been developed and validated in scope of an empirical study. Now, all different types of CDGs can be evaluated according to a defined and uniform set of assessment criteria and, thus, are comparable according to their characteristics and effectiveness.}, language = {en} } @inproceedings{KoenigWolf2018, author = {K{\"o}nig, Johannes Alexander and Wolf, Martin}, title = {Cybersecurity awareness training provided by the competence developing game GHOST}, series = {ACHI 2018 : The Eleventh International Conference on Advances in Computer-Human Interactions}, booktitle = {ACHI 2018 : The Eleventh International Conference on Advances in Computer-Human Interactions}, isbn = {978-1-61208-616-3}, pages = {81 -- 87}, year = {2018}, abstract = {This paper introduces a Competence Developing Game (CDG) for the purpose of a cybersecurity awareness training for businesses. The target audience will be discussed in detail to understand their requirements. It will be explained why and how a mix of business simulation and serious game meets these stakeholder requirements. It will be shown that a tablet and touchscreen based approach is the most suitable solution. In addition, an empirical study will be briefly presented. The study was carried out to examine how an interaction system for a 3D-tablet based CDG has to be designed, to be manageable for non-game experienced employees. Furthermore, it will be explained which serious content is necessary for a Cybersecurity awareness training CDG and how this content is wrapped in the game}, language = {en} } @inproceedings{KoenigVoelkerWolf2018, author = {K{\"o}nig, Johannes Alexander and V{\"o}lker, Veronika and Wolf, Martin}, title = {The user-focused storybuilding framework for competence developing games - a design-framework considering the basics of an educational game's story}, series = {ACHI 2018 : The Eleventh International Conference on Advances in Computer-Human Interactions}, booktitle = {ACHI 2018 : The Eleventh International Conference on Advances in Computer-Human Interactions}, isbn = {978-1-61208-616-3}, pages = {98 -- 106}, year = {2018}, abstract = {During the development of a Competence Developing Game's (CDG) story it is indispensable to understand the target audience. Thereby, CDGs stories represent more than just the plot. The Story is about the Setting, the Characters and the Plot. As a toolkit to support the development of such a story, this paper introduces the UserFocused Storybuilding (short UFoS) Framework for CDGs. The Framework and its utilization will be explained, followed by a description of its development and derivation, including an empirical study. In addition, to simplify the Framework use regarding the CDG's target audience, a new concept of Nine Psychographic Player Types will be explained. This concept of Player Types provides an approach to handle the differences in between players during the UFoS Framework use. Thereby, this article presents a unique approach to the development of target group-differentiated CDGs stories.}, language = {en} } @inproceedings{KoellenspergerBragardPlumetal.2007, author = {K{\"o}llensperger, P. and Bragard, Michael and Plum, T. and De Doncker, R. W.}, title = {The dual GCT : a new high-power device using optimized GCT technology}, series = {Conference record of the 2007 IEEE Industry Applications Conference : 42. IAS annual meeting ; September 23 - 27, 2007, New Orleans, Louisiana, USA}, booktitle = {Conference record of the 2007 IEEE Industry Applications Conference : 42. IAS annual meeting ; September 23 - 27, 2007, New Orleans, Louisiana, USA}, publisher = {IEEE Operations Center}, address = {Piscataway, NJ}, isbn = {978-1-4244-1260-0 (Online)}, doi = {10.1109/07IAS.2007.76}, pages = {358 -- 365}, year = {2007}, language = {en} } @inproceedings{Kurz2006, author = {Kurz, Melanie}, title = {Recognition of shape in virtual visualizations}, series = {Proceedings : November 15 - 17, 2006, Technische Universit{\"a}t Darmstadt, Darmstadt, Germany ; PACE, Partners for the advancement of collaborative engineering education}, booktitle = {Proceedings : November 15 - 17, 2006, Technische Universit{\"a}t Darmstadt, Darmstadt, Germany ; PACE, Partners for the advancement of collaborative engineering education}, publisher = {Techn. Univ.}, address = {Darmstadt}, isbn = {978-3-00-020161-5}, pages = {203 -- 209}, year = {2006}, language = {en} } @inproceedings{Kurz2008, author = {Kurz, Melanie}, title = {On the benefit of moving images for the evaluation of form in virtual space : reflections in model theory}, series = {Design and semantics of form and movement : DeSForM 2008 ; [Hochschule f{\"u}r Gestaltung Offenbach am Main, 6.-7.11.2008]}, booktitle = {Design and semantics of form and movement : DeSForM 2008 ; [Hochschule f{\"u}r Gestaltung Offenbach am Main, 6.-7.11.2008]}, editor = {Feijs, Loe}, publisher = {Philips}, address = {Eindhoven}, isbn = {978-90-809801-2-9}, pages = {31 -- 34}, year = {2008}, language = {en} }