TY - CHAP A1 - Leise, Philipp A1 - Simon, Nicolai A1 - Altherr, Lena T1 - Comparison of Piecewise Linearization Techniques to Model Electric Motor Efficiency Maps: A Computational Study T2 - Operations Research Proceedings 2019 N2 - 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. KW - MINLP KW - Powertrain KW - Piecewise linearization KW - Efficiency optimization Y1 - 2020 SN - 978-3-030-48439-2 SN - 978-3-030-48438-5 U6 - http://dx.doi.org/10.1007/978-3-030-48439-2_55 N1 - Annual International Conference of the German Operations Research Society (GOR), Dresden, Germany, September 4-6, 2019 SP - 457 EP - 463 PB - Springer CY - Cham ER - TY - CHAP A1 - Lenz, Laura L. A1 - Wolf, Martin ED - Kritz, Willy Christian T1 - Economic evaluation of serious games with the comparative assessment framework COSEGA T2 - 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 Y1 - 2014 SN - 978-3-7639-5422-3 SP - 374 EP - 386 PB - Bertelsmann CY - [Bielefeld] ER - TY - CHAP A1 - Limpert, Nicolas A1 - Schiffer, Stefan A1 - Ferrein, Alexander T1 - A Local Planner for Ackermann-Driven Vehicles in ROS SBPL T2 - Proceedings of the International Conference on Pattern Recognition Association of South Africa and Robotics and Mechatronics (PRASA-RobMech), 2015 Y1 - 2015 U6 - http://dx.doi.org/10.1109/RoboMech.2015.7359518 SP - 172 EP - 177 ER - TY - CHAP A1 - Lindenlauf, Simon A1 - Höfken, Hans-Wilhelm A1 - Schuba, Marko T1 - Cold Boot Attacks on DDR2 and DDR3 SDRAM T2 - 10th International Conference on Availability, Reliability and Security (ARES) 2015 Y1 - 2015 U6 - http://dx.doi.org/10.1109/ARES.2015.28 SP - 287 EP - 292 ER - TY - CHAP A1 - Lindner, Marvin A1 - Kolb, Andreas A1 - Ringbeck, Thorsten T1 - New insights into the calibration of ToF-sensors T2 - 2008 IEEE Computer Society Conference on Computer Vision and Pattern Recognition workshops : Anchorage, AK, 23 - 28 June 2008 N2 - 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. Y1 - 2008 SN - 978-1-4244-2339-2 SN - 978-1-4244-2340-8 SP - 1 EP - 5 PB - IEEE Service Center CY - Piscataway, NJ ER - TY - CHAP A1 - Logen, Steffen A1 - Höfken, Hans A1 - Schuba, Marko T1 - Simplifying RAM Forensics : A GUI and Extensions for the Volatility Framework T2 - 2012 Seventh International Conference on Availability, Reliability and Security (ARES), 20-24 August 2012, Prague, Czech Republic N2 - 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. Y1 - 2012 SN - 978-1-4673-2244-7 U6 - http://dx.doi.org/10.1109/ARES.2012.12 SP - 620 EP - 624 PB - IEEE CY - New York ER - TY - CHAP A1 - Lohr, Jürgen T1 - High Quality Streaming und High Definition Media Services N2 - In: Konferenzband zur Konferenz Medienproduktion 2007, 1.12.2008. 29 S. High Quality Streaming beschäftigt sich mit High Definition Television und Mehrkanal Sound. In diesem Beitrag werden die Technologien und Anwendungsperspektiven für HD Medien-Dienstleistungen beschrieben. Der Beitrag entstand im Rahmen der Konferenz Medienproduktion „Expansion und Mobilität“ am 7. Dezember 2007. Der Beitrag beschreibt Geschäftsmodelle, Technologien und neue Anwendungen für High Quality Streaming. Neben der Präsentation wurden auch die Medienproduktionen der unterschiedlichen HQ-Mediendienste vorgeführt. Die Mediendienste sind im Rahmen der Forschungsarbeit High Quality Media Services des Studiengangs Communication and Multimedia Design (Fachbereich Elektrotechnik und Informationstechnik) an der Fachhochschule Aachen entstanden. Eine Marktevaluierung der deutschen und niederländischen Märkte, internationale Expertengesprächen sowie ein Prototypen HDMediaservices bilden die Basis der Forschungsarbeit. Die Mediendienste stehen zur Demonstration unter dem Link media.fh-aachen.de bereit. HQ-Mediendienste bedeuten: Gestochen scharfe Bilder in High Definition, volle Klänge in Surround und das über das Internet, wo doch gerade mal die briefmarkengroßen Bilder mit unscharfen Konturen und krätzenden Klängen der heutigen Portale wie YouTube Alltag sind. KW - HDTV KW - High Quality Streaming KW - High Definition Media Services Y1 - 2007 ER - TY - CHAP A1 - Lorenz, Imke-Sophie A1 - Altherr, Lena A1 - Pelz, Peter F. ED - Neufeld, Janis S. ED - Buscher, Udo ED - Lasch, Rainer ED - Möst, Dominik ED - Schönberger, Jörn T1 - Assessing and Optimizing the Resilience of Water Distribution Systems Using Graph-Theoretical Metrics T2 - Operations Research Proceedings 2019 N2 - Water distribution systems are an essential supply infrastructure for cities. Given that climatic and demographic influences will pose further challenges for these infrastructures in the future, the resilience of water supply systems, i.e. their ability to withstand and recover from disruptions, has recently become a subject of research. To assess the resilience of a WDS, different graph-theoretical approaches exist. Next to general metrics characterizing the network topology, also hydraulic and technical restrictions have to be taken into account. In this work, the resilience of an exemplary water distribution network of a major German city is assessed, and a Mixed-Integer Program is presented which allows to assess the impact of capacity adaptations on its resilience. KW - OR 2019 KW - business analytics KW - decision analytics KW - digital economy KW - mathematical optimization Y1 - 2020 SN - 978-3-030-48439-2 SN - 978-3-030-48438-5 U6 - http://dx.doi.org/10.1007/978-3-030-48439-2_63 N1 - Annual International Conference of the German Operations Research Society (GOR), Dresden, Germany, September 4-6, 2019 SP - 521 EP - 527 PB - Springer CY - Cham ER - TY - CHAP A1 - Lorenz, Imke-Sophie A1 - Altherr, Lena A1 - Pelz, Peter F. T1 - Resilience enhancement of critical infrastructure – graph-theoretical resilience analysis of the water distribution system in the German city of Darmstadt T2 - 14th WCEAM Proceedings N2 - 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. KW - Resilient infrastructure KW - Resilience assessment KW - Resilience metric graph theory KW - Water distribution system KW - Case study Y1 - 2020 SN - 978-3-030-64228-0 SN - 978-3-030-64227-3 U6 - http://dx.doi.org/10.1007/978-3-030-64228-0_13 N1 - 14th WCEAM Proceedings. World Congress on Engineering Asset Management, 28-31 July 2019, Singapore Part of the Lecture Notes in Mechanical Engineering book series (LNME) SP - 137 EP - 149 PB - Springer CY - Cham ER - TY - CHAP A1 - Lorenz, Imke-Sophie B. A1 - Altherr, Lena A1 - Pelz, Peter F. T1 - Graph-theoretic resilience analysis of a water distribution system's topology T2 - World Congress on Resilience, Reliability and Asset Management 2019 N2 - Water suppliers are faced with the great challenge of achieving high-quality and, at the same time, low-cost water supply. In practice, the focus is set on the most beneficial maintenance measures and/or capacity adaptations of existing water distribution systems (WDS). Since climatic and demographic influences will pose further challenges in the future, the resilience enhancement of 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, metrics based on graph theory have been proposed. In this study, a promising approach is applied to assess the resilience of the WDS for a district in a major German City. The conducted analysis provides insight into the process of actively influencing the resilience of WDS KW - Resilience Assessment KW - Graph Theory KW - Water Supply System KW - Case Study Y1 - 2019 N1 - World Congress on Resilience, Reliability and Asset Management, 28-31 July 2019. Furama Riverfront Hotel, Singapore SP - 106 EP - 109 ER - TY - CHAP A1 - Luszczynski, K. A1 - Engels, Elmar T1 - Vergleichende Untersuchung zur Topologie von zelloptimalen, elektromobilitäts-optimierten Ladungsausgleichsvorrichtungen T2 - Tagungsband zur AALE-Tagung 2012 : 9. Fachkonferenz Y1 - 2012 SN - 978-3-8356-3305-6 N1 - AALE 2012 SP - 165 EP - 174 PB - Oldenbourg Industrieverlag CY - München ER - TY - CHAP A1 - Maike, Müller A1 - Lenz, Laura A1 - Wolf, Martin T1 - Steigerung der Effektivität durch Prozessmodellierungs-Tools - Änderbarkeit und Transparenz von Prozessen am Beispiel der Business Simulation Apollo 13 T2 - Informatik 2014 N2 - Die Nutzung von Prozessmodellierungsmethoden oder - werkzeugen kann erheblichen Einfluss auf die Effektivität von Prozessen haben. Das gilt insbesondere für Situationen, in denen Personen unter Stress stehen oder ungeübt sind. In diesen Fällen geben Prozessmodelle konkrete Empfehlungen, nach denen sich die handelnden Personen richten könnten. In Experimenten mit der Business-Simulation Apollo 13 haben wir den Effekt eines Einsatzes von Prozessmodellierungsmethoden und -werkzeugen untersucht. Bereits bekannte Theorien (z.B. über geeignete Verhältnisse von Kommunikationsinhalten) konnten bestätigt werden. Darüber hinaus haben wir eine besondere Bedeutung der Übertragbarkeit von Prozessmodellen in konkrete Handlungen identifiziert. Y1 - 2014 SN - 978-3-88579-626-8 SN - 1617-5468 SP - 357 EP - 369 PB - Gesellschaft für Informatik e.V. CY - Bonn ER - TY - CHAP A1 - Marco, Heather G. A1 - Ferrein, Alexander T1 - AGNES: The African-German Network of Excellence in Science T2 - Proceedings of the 2nd Developing World Robotics Forum, Workshop at IEEE AFRICON 2017 Y1 - 2017 SP - 1 EP - 2 ER - TY - CHAP A1 - Mataré, Victor A1 - Schiffer, Stefan A1 - Ferrein, Alexander ED - Steinbauer, Gerald ED - Ferrein, Alexander T1 - golog++ : An integrative system design T2 - CogRob 2018. Cognitive Robotics Workshop : Proceedings of the 11th Cognitive Robotics Workshop 2018 co-located with 16th International Conference on Principles of Knowledge Representation and Reasoning (KR 2018) Tempe, AZ, USA, October 27th, 2018 Y1 - 2019 SN - 1613-0073 SP - 29 EP - 35 ER - TY - CHAP A1 - Meck, Marvin M. A1 - Müller, Tim M. A1 - Altherr, Lena A1 - Pelz, Peter F. T1 - Improving an industrial cooling system using MINLP, considering capital and operating costs T2 - Operations Research Proceedings 2019 N2 - The chemical industry is one of the most important industrial sectors in Germany in terms of manufacturing revenue. While thermodynamic boundary conditions often restrict the scope for reducing the energy consumption of core processes, secondary processes such as cooling offer scope for energy optimisation. In this contribution, we therefore model and optimise an existing cooling system. The technical boundary conditions of the model are provided by the operators, the German chemical company BASF SE. In order to systematically evaluate different degrees of freedom in topology and operation, we formulate and solve a Mixed-Integer Nonlinear Program (MINLP), and compare our optimisation results with the existing system. KW - Engineering optimisation KW - Mixed-integer programming KW - Industrial optimisation KW - Cooling system KW - Process engineering Y1 - 2020 SN - 978-3-030-48438-5 (Print) SN - 978-3-030-48439-2 (Online) U6 - http://dx.doi.org/10.1007/978-3-030-48439-2_61 N1 - Annual International Conference of the German Operations Research Society (GOR), Dresden, Germany, September 4-6, 2019. SP - 505 EP - 512 PB - Springer CY - Cham ER - TY - CHAP A1 - Moll, Florian A1 - Köhler, Klemens A1 - Wolf, Martin T1 - Konzeption von IT-Sicherheitslösungen unter ethischen Gesichtspunkten am Beispiel einer Monitoring-App für mobile Endgeräte T2 - Angewandte Forschung in der Wirtschaftsinformatik 2019 : Tagungsband zur 32. AKWI-Jahrestagung N2 - Die steigende Popularität von mobilen Endgeräten im privaten und geschäftlichen Umfeld geht mit einem Anstieg an Sicherheitslücken und somit potentiellen Angriffsflächen einher. Als ein Element der technischen und organisatorischen Maßnahmen zum Schutz eines Netzwerkes können Monitoring-Apps dienen, die unerwünschtes Verhalten und Angriffe erkennen. Die automatisierte Überwachung von Endgeräten ist jedoch rechtlich und ethisch komplex. Dies in Kombination mit einer hohen Sensibilität der Nutzer und Nutzerinnen dieser Geräte in Bezug auf Privatsphäre, kann zu einer geringen Akzeptanz und Compliance führen. Eine datenschutzrechtlich und ethisch einwandfreie Konzeption solcher Apps bereits im Designprozess führt zu höherer Akzeptanz und verbessert so die Effizienz. Diese Analyse beschreibt Möglichkeiten zur Umsetzung. Y1 - 2019 SN - 978-3-944330-62-4 SP - 61 EP - 72 PB - mana-Buch CY - Heide ER - TY - CHAP A1 - Müller, Tim M. A1 - Altherr, Lena A1 - Ahola, Marja A1 - Schabel, Samuel A1 - Pelz, Peter F. ED - Rodrigues, H. C. T1 - Multi-Criteria optimization of pressure screen systems in paper recycling – balancing quality, yield, energy consumption and system complexity T2 - EngOpt 2018 Proceedings of the 6th International Conference on Engineering Optimization N2 - The paper industry is the industry with the third highest energy consumption in the European Union. Using recycled paper instead of fresh fibers for papermaking is less energy consuming and saves resources. However, adhesive contaminants in recycled paper are particularly problematic since they reduce the quality of the resulting paper-product. To remove as many contaminants and at the same time obtain as many valuable fibres as possible, fine screening systems, consisting of multiple interconnected pressure screens, are used. Choosing the best configuration is a non-trivial task: The screens can be interconnected in several ways, and suitable screen designs as well as operational parameters have to be selected. Additionally, one has to face conflicting objectives. In this paper, we present an approach for the multi-criteria optimization of pressure screen systems based on Mixed-Integer Nonlinear Programming. We specifically focus on a clear representation of the trade-off between different objectives. Y1 - 2019 SN - 978-3-319-97773-7 U6 - http://dx.doi.org/10.1007/978-3-319-97773-7_105 N1 - EngOpt 2018 Proceedings of the 6th International Conference on Engineering Optimization. 17-19 September 2018. Lisboa, Portugal PB - Springer International Publishing CY - Basel ER - TY - CHAP A1 - Müller, Tim M. A1 - Altherr, Lena A1 - Leise, Philipp A1 - Pelz, Peter F. T1 - Optimization of pumping systems for buildings: Experimental validation of different degrees of model detail on a modular test rig T2 - Operations Research Proceedings 2019 N2 - Successful optimization requires an appropriate model of the system under consideration. When selecting a suitable level of detail, one has to consider solution quality as well as the computational and implementation effort. In this paper, we present a MINLP for a pumping system for the drinking water supply of high-rise buildings. We investigate the influence of the granularity of the underlying physical models on the solution quality. Therefore, we model the system with a varying level of detail regarding the friction losses, and conduct an experimental validation of our model on a modular test rig. Furthermore, we investigate the computational effort and show that it can be reduced by the integration of domain-specific knowledge. KW - Experimental validation KW - MINLP KW - Engineering optimization KW - Water supply system KW - Network design Y1 - 2020 SN - 978-3-030-48438-5 U6 - http://dx.doi.org/10.1007/978-3-030-48439-2_58 N1 - Annual International Conference of the German Operations Research Society (GOR), Dresden, Germany, September 4-6, 2019 SP - 481 EP - 488 PB - Springer CY - Cham ER - TY - CHAP A1 - Müller, Tim M. A1 - Schmitt, Andreas A1 - Leise, Philipp A1 - Meck, Tobias A1 - Altherr, Lena A1 - Pelz, Peter F. A1 - Pfetsch, Marc E. T1 - Validation of an optimized resilient water supply system T2 - Uncertainty in Mechanical Engineering N2 - Component failures within water supply systems can lead to significant performance losses. One way to address these losses is the explicit anticipation of failures within the design process. We consider a water supply system for high-rise buildings, where pump failures are the most likely failure scenarios. We explicitly consider these failures within an early design stage which leads to a more resilient system, i.e., a system which is able to operate under a predefined number of arbitrary pump failures. We use a mathematical optimization approach to compute such a resilient design. This is based on a multi-stage model for topology optimization, which can be described by a system of nonlinear inequalities and integrality constraints. Such a model has to be both computationally tractable and to represent the real-world system accurately. We therefore validate the algorithmic solutions using experiments on a scaled test rig for high-rise buildings. The test rig allows for an arbitrary connection of pumps to reproduce scaled versions of booster station designs for high-rise buildings. We experimentally verify the applicability of the presented optimization model and that the proposed resilience properties are also fulfilled in real systems. KW - Optimization KW - Mixed-integer nonlinear programming KW - Water distribution system KW - Resilience KW - Validation Y1 - 2021 SN - 978-3-030-77255-0 SN - 978-3-030-77256-7 U6 - http://dx.doi.org/10.1007/978-3-030-77256-7_7 N1 - Proceedings of the 4th International Conference on Uncertainty in Mechanical Engineering (ICUME 2021), June 7–8, 2021 SP - 70 EP - 80 PB - Springer CY - Cham ER - TY - CHAP A1 - Nees, Franz A1 - Stengel, Ingo A1 - Meister, Vera G. A1 - Barton, Thomas A1 - Herrmann, Frank A1 - Müller, Christian A1 - Wolf, Martin T1 - Angewandte Forschung in der Wirtschaftsinformatik 2020 : Tagungsband zur 33. AKWI-Jahrestagung am 14.09.2020, ausgerichtet von der Hochschule Karlsruhe - Wirtschaft und Technik / hrsg. von Franz Nees, Ingo Stengel, Vera G. Meister, Thomas Barton, Frank Herrmann, Christian Müller, Martin R. Wolf N2 - Tagungsbeiträge aus den Bereichen KI, Prozessorganisation und Plattformen für Geschäftsprozesse, Sicherheit und Datenschutz sowie Prototypen und Modelle. Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:526-opus4-13840 SN - 978-3-944330-66-2 PB - mana-Buch CY - Heide ER -