@article{AsanteAsamaniKleefeldWade2020, author = {Asante-Asamani, E.O. and Kleefeld, Andreas and Wade, B.A.}, title = {A second-order exponential time differencing scheme for non-linear reaction-diffusion systems with dimensional splitting}, series = {Journal of Computational Physics}, volume = {415}, journal = {Journal of Computational Physics}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0021-9991}, doi = {10.1016/j.jcp.2020.109490}, year = {2020}, abstract = {A second-order L-stable exponential time-differencing (ETD) method is developed by combining an ETD scheme with approximating the matrix exponentials by rational functions having real distinct poles (RDP), together with a dimensional splitting integrating factor technique. A variety of non-linear reaction-diffusion equations in two and three dimensions with either Dirichlet, Neumann, or periodic boundary conditions are solved with this scheme and shown to outperform a variety of other second-order implicit-explicit schemes. An additional performance boost is gained through further use of basic parallelization techniques.}, language = {en} } @inproceedings{RekePeterSchulteTiggesetal.2020, author = {Reke, Michael and Peter, Daniel and Schulte-Tigges, Joschua and Schiffer, Stefan and Ferrein, Alexander and Walter, Thomas and Matheis, Dominik}, title = {A Self-Driving Car Architecture in ROS2}, series = {2020 International SAUPEC/RobMech/PRASA Conference, Cape Town, South Africa}, booktitle = {2020 International SAUPEC/RobMech/PRASA Conference, Cape Town, South Africa}, publisher = {IEEE}, address = {New York, NY}, isbn = {978-1-7281-4162-6}, doi = {10.1109/SAUPEC/RobMech/PRASA48453.2020.9041020}, pages = {1 -- 6}, year = {2020}, abstract = {In this paper we report on an architecture for a self-driving car that is based on ROS2. Self-driving cars have to take decisions based on their sensory input in real-time, providing high reliability with a strong demand in functional safety. In principle, self-driving cars are robots. However, typical robot software, in general, and the previous version of the Robot Operating System (ROS), in particular, does not always meet these requirements. With the successor ROS2 the situation has changed and it might be considered as a solution for automated and autonomous driving. Existing robotic software based on ROS was not ready for safety critical applications like self-driving cars. We propose an architecture for using ROS2 for a self-driving car that enables safe and reliable real-time behaviour, but keeping the advantages of ROS such as a distributed architecture and standardised message types. First experiments with an automated real passenger car at lower and higher speed-levels show that our approach seems feasible for autonomous driving under the necessary real-time conditions.}, language = {en} } @inproceedings{EltesterFerreinSchiffer2020, author = {Eltester, Niklas Sebastian and Ferrein, Alexander and Schiffer, Stefan}, title = {A smart factory setup based on the RoboCup logistics league}, series = {2020 IEEE Conference on Industrial Cyberphysical Systems (ICPS)}, booktitle = {2020 IEEE Conference on Industrial Cyberphysical Systems (ICPS)}, publisher = {IEEE}, address = {New York, NY}, doi = {10.1109/ICPS48405.2020.9274766}, pages = {297 -- 302}, year = {2020}, abstract = {In this paper we present SMART-FACTORY, a setup for a research and teaching facility in industrial robotics that is based on the RoboCup Logistics League. It is driven by the need for developing and applying solutions for digital production. Digitization receives constantly increasing attention in many areas, especially in industry. The common theme is to make things smart by using intelligent computer technology. Especially in the last decade there have been many attempts to improve existing processes in factories, for example, in production logistics, also with deploying cyber-physical systems. An initiative that explores challenges and opportunities for robots in such a setting is the RoboCup Logistics League. Since its foundation in 2012 it is an international effort for research and education in an intra-warehouse logistics scenario. During seven years of competition a lot of knowledge and experience regarding autonomous robots was gained. This knowledge and experience shall provide the basis for further research in challenges of future production. The focus of our SMART-FACTORY is to create a stimulating environment for research on logistics robotics, for teaching activities in computer science and electrical engineering programmes as well as for industrial users to study and explore the feasibility of future technologies. Building on a very successful history in the RoboCup Logistics League we aim to provide stakeholders with a dedicated facility oriented at their individual needs.}, language = {en} } @article{KetelhutBrueggeGoelletal.2020, author = {Ketelhut, Maike and Br{\"u}gge, G. M. and G{\"o}ll, Fabian and Braunstein, Bjoern and Albracht, Kirsten and Abel, Dirk}, title = {Adaptive iterative learning control of an industrial robot during neuromuscular training}, series = {IFAC PapersOnLine}, volume = {53}, journal = {IFAC PapersOnLine}, number = {2}, publisher = {Elsevier}, address = {Amsterdam}, issn = {2405-8963}, doi = {10.1016/j.ifacol.2020.12.741}, pages = {16468 -- 16475}, year = {2020}, abstract = {To prevent the reduction of muscle mass and loss of strength coming along with the human aging process, regular training with e.g. a leg press is suitable. However, the risk of training-induced injuries requires the continuous monitoring and controlling of the forces applied to the musculoskeletal system as well as the velocity along the motion trajectory and the range of motion. In this paper, an adaptive norm-optimal iterative learning control algorithm to minimize the knee joint loadings during the leg extension training with an industrial robot is proposed. The response of the algorithm is tested in simulation for patients with varus, normal and valgus alignment of the knee and compared to the results of a higher-order iterative learning control algorithm, a robust iterative learning control and a recently proposed conventional norm-optimal iterative learning control algorithm. Although significant improvements in performance are made compared to the conventional norm-optimal iterative learning control algorithm with a small learning factor, for the developed approach as well as the robust iterative learning control algorithm small steady state errors occur.}, language = {en} } @inproceedings{EggertStanke2020, author = {Eggert, Mathias and Stanke, Max-Alexander}, title = {Adoption of Integrated Voice Assistants in Health Care- Requirements and Design Guidelines}, publisher = {GITO}, address = {Berlin}, doi = {10.30844/wi_2020_k2-eggert}, pages = {16 Seiten}, year = {2020}, abstract = {Integrated voice assistants (IVA) receive more and more attention and are widespread for entertainment use cases, such as radio hearing or web searches. At the same time, the health care segment suffers in process inefficiency and missing staff, whereas the usage of IVA has the potential to improve caring processes and patient satisfaction. By applying a design science approach and based on a qualitative study, we identify IVA requirements, barriers and design guidelines for the health care sector. The results reveal three important IVA functions: the ability to set appointments with care service staff, the documentation of health history and the communication with service staff. Integration, system stability and volume control are the most important nonfunctional requirements. Based on the interview results and project experiences, six design and implementation guidelines are derived.}, language = {en} } @article{BungErpicumTullis2020, author = {Bung, Daniel Bernhard and Erpicum, S{\´e}bastien and Tullis, Blanke P.}, title = {Advances in hydraulic structures engineering}, series = {Journal of Hydraulic Engineering}, volume = {147}, journal = {Journal of Hydraulic Engineering}, number = {1}, publisher = {ASCE}, address = {Reston, Va.}, issn = {0733-9429 (Druckausgabe)}, doi = {10.1061/(ASCE)HY.1943-7900.0001851}, pages = {1 Seite}, year = {2020}, language = {en} } @inproceedings{GeibenGoettenHavermann2020, author = {Geiben, Benedikt and G{\"o}tten, Falk and Havermann, Marc}, title = {Aerodynamic analysis of a winged sub-orbital spaceplane}, publisher = {DGLR}, address = {Bonn}, doi = {10.25967/530170}, year = {2020}, abstract = {This paper primarily presents an aerodynamic CFD analysis of a winged spaceplane geometry based on the Japanese Space Walker proposal. StarCCM was used to calculate aerodynamic coefficients for a typical space flight trajectory including super-, trans- and subsonic Mach numbers and two angles of attack. Since the solution of the RANS equations in such supersonic flight regimes is still computationally expensive, inviscid Euler simulations can principally lead to a significant reduction in computational effort. The impact on accuracy of aerodynamic properties is further analysed by comparing both methods for different flight regimes up to a Mach number of 4.}, language = {en} } @article{MoratFaudeHanssenetal.2020, author = {Morat, Mareike and Faude, Oliver and Hanssen, Henner and Ludyga, Sebastian and Zacher, Jonas and Eibl, Angi and Albracht, Kirsten and Donath, Lars}, title = {Agility Training to Integratively Promote Neuromuscular, Cognitive, Cardiovascular and Psychosocial Function in Healthy Older Adults: A Study Protocol of a One-Year Randomized-Controlled Trial}, series = {International Journal of Environmental Research and Public Health}, volume = {17}, journal = {International Journal of Environmental Research and Public Health}, number = {6}, publisher = {MDPI}, address = {Basel}, issn = {1660-4601}, doi = {10.3390/ijerph17061853}, pages = {1 -- 14}, year = {2020}, abstract = {Exercise training effectively mitigates aging-induced health and fitness impairments. Traditional training recommendations for the elderly focus separately on relevant physiological fitness domains, such as balance, flexibility, strength and endurance. Thus, a more holistic and functional training framework is needed. The proposed agility training concept integratively tackles spatial orientation, stop and go, balance and strength. The presented protocol aims at introducing a two-armed, one-year randomized controlled trial, evaluating the effects of this concept on neuromuscular, cardiovascular, cognitive and psychosocial health outcomes in healthy older adults. Eighty-five participants were enrolled in this ongoing trial. Seventy-nine participants completed baseline testing and were block-randomized to the agility training group or the inactive control group. All participants undergo pre- and post-testing with interim assessment after six months. The intervention group currently receives supervised, group-based agility training twice a week over one year, with progressively demanding perceptual, cognitive and physical exercises. Knee extension strength, reactive balance, dual task gait speed and the Agility Challenge for the Elderly (ACE) serve as primary endpoints and neuromuscular, cognitive, cardiovascular, and psychosocial meassures serve as surrogate secondary outcomes. Our protocol promotes a comprehensive exercise training concept for older adults, that might facilitate stakeholders in health and exercise to stimulate relevant health outcomes without relying on excessively time-consuming physical activity recommendations.}, language = {en} } @article{GoettenHavermannBraunetal.2020, author = {G{\"o}tten, Falk and Havermann, Marc and Braun, Carsten and Marino, Matthew and Bil, Cees}, title = {Airfoil drag at low-to-medium reynolds numbers: A novel estimation method}, series = {AIAA Journal}, volume = {58}, journal = {AIAA Journal}, number = {7}, publisher = {AIAA}, address = {Reston, Va.}, issn = {1533-385X}, doi = {10.2514/1.J058983}, pages = {2791 -- 2805}, year = {2020}, abstract = {This paper presents a novel method for airfoil drag estimation at Reynolds numbers between 4×10⁵ and 4×10⁶. The novel method is based on a systematic study of 40 airfoils applying over 600 numerical simulations and considering natural transition. The influence of the airfoil thickness-to-chord ratio, camber, and freestream Reynolds number on both friction and pressure drag is analyzed in detail. Natural transition significantly affects drag characteristics and leads to distinct drag minima for different Reynolds numbers and thickness-to-chord ratios. The results of the systematic study are used to develop empirical correlations that can accurately predict an airfoil drag at low-lift conditions. The new approach estimates a transition location based on airfoil thickness-to-chord ratio, camber, and Reynolds number. It uses the transition location in a mixed laminar-turbulent skin-friction calculation, and corrects the skin-friction coefficient for separation effects. Pressure drag is estimated separately based on correlations of thickness-to-chord ratio, camber, and Reynolds number. The novel method shows excellent accuracy when compared with wind-tunnel measurements of multiple airfoils. It is easily integrable into existing aircraft design environments and is highly beneficial in the conceptual design stage.}, language = {en} } @article{RichterWichernGroempingetal.2020, author = {Richter, L. and Wichern, M. and Gr{\"o}mping, Markus and Robecke, U. and Haberkamp, J.}, title = {Ammonium recovery from process water of digested sludge dewatering by membrane contactors}, series = {Water Practice and Technology}, volume = {15}, journal = {Water Practice and Technology}, number = {1}, publisher = {IWA Publishing}, address = {London}, issn = {1751-231X}, doi = {10.2166/wpt.2020.002}, pages = {84 -- 91}, year = {2020}, abstract = {Membrane contactors are a promising alternative for nitrogen removal and recovery from process water compared to other physicochemical and biological sidestream treatment processes. M{\"u}nster wastewater treatment plant (WWTP) is the first municipal WWTP in Germany operating a full-scale membrane contactor system to improve the nitrogen elimination and recovery efficiency. Factors influencing the operation and membrane performance are investigated in an accompanying research project. Additional operational aspects of the applied membrane modules are investigated in detail using a bench-scale membrane contactor. First results of the full-scale application demonstrate a high nitrogen removal efficiency of >95\%.}, language = {de} }