TY - JOUR A1 - Otten, Dennis A1 - Weber, Tobias A1 - Arent, Jan-Christoph T1 - Manufacturing Process Simulation – On Its Way to Industrial Application JF - International Journal of Aviation, Aeronautics, and Aerospace N2 - Manufacturing process simulation (MPS) has become more and more important for aviation and the automobile industry. A highly competitive market requires the use of high performance metals and composite materials in combination with reduced manufacturing cost and time as well as a minimization of the time to market for a new product. However, the use of such materials is expensive and requires sophisticated manufacturing processes. An experience based process and tooling design followed by a lengthy trial-and-error optimization is just not contemporary anymore. Instead, a tooling design process aided by simulation is used more often. This paper provides an overview of the capabilities of MPS in the fields of sheet metal forming and prepreg autoclave manufacturing of composite parts summarizing the resulting benefits for tooling design and manufacturing engineering. The simulation technology is explained briefly in order to show several simplification and optimization techniques for developing industrialized simulation approaches. Small case studies provide examples of an efficient application on an industrial scale. Y1 - 2018 U6 - https://doi.org/10.15394/ijaaa.2018.1217 SN - 2374-6793 VL - 5 IS - 2 PB - Embry-Riddle Aeronautical University CY - Daytona Beach, Fla. ER - TY - JOUR A1 - Weber, Tobias A1 - Ruff-Stahl, Hans-Joachim K. T1 - Advances in Composite Manufacturing of Helicopter Parts JF - International Journal of Aviation, Aeronautics, and Aerospace Y1 - 2017 U6 - https://doi.org/10.15394/ijaaa.2017.1153 SN - 2374-6793 VL - 4 IS - 1 ER - TY - JOUR A1 - Weber, Tobias A1 - Arent, Jan-Christoph A1 - Steffen, Lucas A1 - Balvers, Johannes M. A1 - Duhovic, Miro T1 - Thermal optimization of composite autoclave molds using the shift factor approach for boundary condition estimation JF - Journal of Composite Materials Y1 - 2017 U6 - https://doi.org/10.1177/0021998317699868 SN - 1530-793X VL - 51 IS - 12 SP - 1753 EP - 1767 PB - Sage CY - London ER - TY - CHAP A1 - Otten, D. A1 - Schmidt, M. A1 - Weber, Tobias T1 - Advances in Determination of Material Parameters for Functional Simulations Based on Process Simulations T2 - SAMPE Europe Conference 16 Liege Y1 - 2016 SN - 978-1-5108-3800-0 SP - 570 EP - 577 ER - TY - CHAP A1 - Weber, Tobias A1 - Tellis, Jane J. A1 - Duhovic, Miro T1 - Characterization of tool-part-interaction an interlaminar friction for manufacturing process simulation T2 - ECCM 17, 17th European Conference on Composite Materials, München, DE, Jun 26-30, 2016 Y1 - 2016 SN - 978-3-00-053387-7 SP - 1 EP - 7 ER - TY - JOUR A1 - Weber, Tobias A1 - Arent, Jan-Christoph A1 - Münch, Lukas A1 - Duhovic, Miro A1 - Balvers, Johannes M. T1 - A fast method for the generation of boundary conditions for thermal autoclave simulation JF - Composites Part A N2 - Manufacturing process simulation enables the evaluation and improvement of autoclave mold concepts early in the design phase. To achieve a high part quality at low cycle times, the thermal behavior of the autoclave mold can be investigated by means of simulations. Most challenging for such a simulation is the generation of necessary boundary conditions. Heat-up and temperature distribution in an autoclave mold are governed by flow phenomena, tooling material and shape, position within the autoclave, and the chosen autoclave cycle. This paper identifies and summarizes the most important factors influencing mold heat-up and how they can be introduced into a thermal simulation. Thermal measurements are used to quantify the impact of the various parameters. Finally, the gained knowledge is applied to develop a semi-empirical approach for boundary condition estimation that enables a simple and fast thermal simulation of the autoclave curing process with reasonably high accuracy for tooling optimization. Y1 - 2016 U6 - https://doi.org/10.1016/j.compositesa.2016.05.036 SN - 1359-835X VL - 88 SP - 216 EP - 225 PB - Elsevier CY - Amsterdam ER - TY - CHAP A1 - Hailer, Benjamin A1 - Weber, Tobias A1 - Arent, Jan-Christoph T1 - Manufacturing Process Simulation for Autoclave-Produced Sandwich Structures T2 - Proceedings of SAMPE Europe Conference 2019, Nantes, France Y1 - 2019 SP - 1 EP - 8 ER - TY - CHAP A1 - Weber, Tobias A1 - Englhard, Markus A1 - Hailer, Benjamin A1 - Arent, Jan-Christoph T1 - Manufacturing Process Simulation for the Prediction of Tool-Part-Interaction and Ply Wrinkling T2 - Proceedings of SAMPE Europe Conference 2019, Nantes, France Y1 - 2019 SP - 1 EP - 10 ER - TY - CHAP A1 - Weber, Tobias A1 - Englhard, Markus A1 - Hailer, Benjamin A1 - Arent, Jan-Christoph T1 - Manufacturing Process Simulation for the Prediction of Tool-Part-Interaction and Ply Wrinkling T2 - Proceedings of SAMPE Europe Conference, Amiens , France Y1 - 2015 SP - 1 EP - 10 ER - TY - CHAP A1 - Weber, Tobias T1 - Manufacturing Process Simulation for Tooling Optimization: Reduction of Quality Issues During Autoclave Manufacturing of Composite Parts T2 - Proceedings of SAMPE Europe Conference 2015, Amiens, France Y1 - 2015 SP - 1 EP - 8 ER - TY - CHAP A1 - Otten, D. A1 - Schmid, M. A1 - Weber, Tobias T1 - Advances In Sheet Metal-Forming: Reduction Of Tooling Cost By Methodical Optimization T2 - Proceedings of SAMPE Europe Conference, Amiens , France Y1 - 2015 ER - TY - JOUR A1 - Pfaff, Raphael A1 - Gidaszewski, Lars A1 - Schmidt, Bernd T1 - Berücksichtigung von No Fault Found im Diagnose- und Instandhaltungssystem von Schienenfahrzeugen JF - ETR - Eisenbahntechnische Rundschau N2 - Intermittierende und nicht reproduzierbare Fehler, auch als No Fault Found bezeichnet, treten in praktisch allen Bereichen auf und sorgen für hohe Kosten. Diese sind häufig auf unpräzise Fehlerbeschreibungen zurückzuführen. Im vorliegenden Beitrag werden Anpassungen der Vorgehensweise bei der Entwicklung und Anpassungen des Diagnosesystems vorgeschlagen. Y1 - 2020 SN - 0013-2845 IS - 5 SP - 56 EP - 59 PB - DVV Media Group CY - Hamburg ER - TY - CHAP A1 - Schmidts, Oliver A1 - Kraft, Bodo A1 - Winkens, Marvin A1 - Zündorf, Albert T1 - Catalog integration of low-quality product data by attribute label ranking T2 - Proceedings of the 9th International Conference on Data Science, Technology and Applications DATA - Volume 1 N2 - The integration of product data from heterogeneous sources and manufacturers into a single catalog is often still a laborious, manual task. Especially small- and medium-sized enterprises face the challenge of timely integrating the data their business relies on to have an up-to-date product catalog, due to format specifications, low quality of data and the requirement of expert knowledge. Additionally, modern approaches to simplify catalog integration demand experience in machine learning, word vectorization, or semantic similarity that such enterprises do not have. Furthermore, most approaches struggle with low-quality data. We propose Attribute Label Ranking (ALR), an easy to understand and simple to adapt learning approach. ALR leverages a model trained on real-world integration data to identify the best possible schema mapping of previously unknown, proprietary, tabular format into a standardized catalog schema. Our approach predicts multiple labels for every attribute of an inpu t column. The whole column is taken into consideration to rank among these labels. We evaluate ALR regarding the correctness of predictions and compare the results on real-world data to state-of-the-art approaches. Additionally, we report findings during experiments and limitations of our approach. Y1 - 2020 SN - 978-989-758-440-4 U6 - https://doi.org/10.5220/0009831000900101 N1 - 9th International Conference on Data Science, Technologies and Applications (DATA 2020), 7 - 9 July 2020, online SP - 90 EP - 101 PB - SciTePress CY - Setúbal, Portugal ER - TY - JOUR A1 - Franko, Josef A1 - Du, Shengzhi A1 - Kallweit, Stephan A1 - Duelberg, Enno Sebastian A1 - Engemann, Heiko T1 - Design of a Multi-Robot System for Wind Turbine Maintenance JF - Energies N2 - The maintenance of wind turbines is of growing importance considering the transition to renewable energy. This paper presents a multi-robot-approach for automated wind turbine maintenance including a novel climbing robot. Currently, wind turbine maintenance remains a manual task, which is monotonous, dangerous, and also physically demanding due to the large scale of wind turbines. Technical climbers are required to work at significant heights, even in bad weather conditions. Furthermore, a skilled labor force with sufficient knowledge in repairing fiber composite material is rare. Autonomous mobile systems enable the digitization of the maintenance process. They can be designed for weather-independent operations. This work contributes to the development and experimental validation of a maintenance system consisting of multiple robotic platforms for a variety of tasks, such as wind turbine tower and rotor blade service. In this work, multicopters with vision and LiDAR sensors for global inspection are used to guide slower climbing robots. Light-weight magnetic climbers with surface contact were used to analyze structure parts with non-destructive inspection methods and to locally repair smaller defects. Localization was enabled by adapting odometry for conical-shaped surfaces considering additional navigation sensors. Magnets were suitable for steel towers to clamp onto the surface. A friction-based climbing ring robot (SMART— Scanning, Monitoring, Analyzing, Repair and Transportation) completed the set-up for higher payload. The maintenance period could be extended by using weather-proofed maintenance robots. The multi-robot-system was running the Robot Operating System (ROS). Additionally, first steps towards machine learning would enable maintenance staff to use pattern classification for fault diagnosis in order to operate safely from the ground in the future. Y1 - 2020 U6 - https://doi.org/10.3390/en13102552 SN - 1996-1073 VL - 13 IS - 10 SP - Article 2552 PB - MDPI CY - Basel ER - TY - CHAP A1 - Duffner, Markus A1 - Moorkamp, Wilfried A1 - Peterson, Leif Arne A1 - Uibel, Thomas ED - Kuhlmann, Ulrike T1 - Untersuchungen zur Tragfähigkeit und Steifigkeit eines neuartigen Wandelements in Holzbauweisen T2 - Doktorandenkolloquium Holzbau Forschung + Praxis : Stuttgart, 08./09. März 2018 Y1 - 2018 SP - 131 EP - 139 PB - Universität Stuttgart, Institut für Konstruktion und Entwurf CY - Stuttgart ER - TY - JOUR A1 - Keller, Johannes A1 - Rath, Volker A1 - Bruckmann, Johanna A1 - Mottaghy, Darius A1 - Clauser, Christoph A1 - Wolf, Andreas A1 - Seidler, Ralf A1 - Bücker, H. Martin A1 - Klitzsch, Norbert T1 - SHEMAT-Suite: An open-source code for simulating flow, heat and species transport in porous media JF - SoftwareX N2 - SHEMAT-Suite is a finite-difference open-source code for simulating coupled flow, heat and species transport in porous media. The code, written in Fortran-95, originates from geoscientific research in the fields of geothermics and hydrogeology. It comprises: (1) a versatile handling of input and output, (2) a modular framework for subsurface parameter modeling, (3) a multi-level OpenMP parallelization, (4) parameter estimation and data assimilation by stochastic approaches (Monte Carlo, Ensemble Kalman filter) and by deterministic Bayesian approaches based on automatic differentiation for calculating exact (truncation error-free) derivatives of the forward code. Y1 - 2020 U6 - https://doi.org/10.1016/j.softx.2020.100533 SN - 2352-7110 VL - 12 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Nobis, Moritz A1 - Schmitt, Carlo A1 - Schemm, Ralf A1 - Schnettler, Armin T1 - Pan-European CVAR-constrained stochastic unit commitment in day-ahead and intraday electricity markets JF - Energies N2 - The fundamental modeling of energy systems through individual unit commitment decisions is crucial for energy system planning. However, current large-scale models are not capable of including uncertainties or even risk-averse behavior arising from forecasting errors of variable renewable energies. However, risks associated with uncertain forecasting errors have become increasingly relevant within the process of decarbonization. The intraday market serves to compensate for these forecasting errors. Thus, the uncertainty of forecasting errors results in uncertain intraday prices and quantities. Therefore, this paper proposes a two-stage risk-constrained stochastic optimization approach to fundamentally model unit commitment decisions facing an uncertain intraday market. By the nesting of Lagrangian relaxation and an extended Benders decomposition, this model can be applied to large-scale, e.g., pan-European, power systems. The approach is applied to scenarios for 2023—considering a full nuclear phase-out in Germany—and 2035—considering a full coal phase-out in Germany. First, the influence of the risk factors is evaluated. Furthermore, an evaluation of the market prices shows an increase in price levels as well as an increasing day-ahead-intraday spread in 2023 and in 2035. Finally, it is shown that intraday cross-border trading has a significant influence on trading volumes and prices and ensures a more efficient allocation of resources. Y1 - 2020 U6 - https://doi.org/10.3390/en13092339 SN - 1996-1073 N1 - Special Issue Uncertainties and Risk Management in Competitive Energy Markets VL - 13 IS - Art. 2339 SP - 1 EP - 35 PB - MDPI CY - Basel ER - TY - JOUR A1 - Emhardt, Selina A1 - Jarodzka, Halszka A1 - Brand-Gruwel, Saskia A1 - Drumm, Christian A1 - Gog, Tamara van T1 - Introducing eye movement modeling examples for programming education and the role of teacher's didactic guidance JF - ETRA '20 Short Papers: ACM Symposium on Eye Tracking Research and Applications N2 - In this article, we introduce how eye-tracking technology might become a promising tool to teach programming skills, such as debugging with ‘Eye Movement Modeling Examples’ (EMME). EMME are tutorial videos that visualize an expert's (e.g., a programming teacher's) eye movements during task performance to guide students’ attention, e.g., as a moving dot or circle. We first introduce the general idea behind the EMME method and present studies that showed first promising results regarding the benefits of EMME to support programming education. However, we argue that the instructional design of EMME varies notably across them, as evidence-based guidelines on how to create effective EMME are often lacking. As an example, we present our ongoing research on the effects of different ways to instruct the EMME model prior to video creation. Finally, we highlight open questions for future investigations that could help improving the design of EMME for (programming) education. Y1 - 2020 U6 - https://doi.org/10.1145/3379156.3391978 IS - Art. 52 SP - 1 EP - 4 PB - ACM CY - New York ER - TY - JOUR A1 - Heinke, Lars N. A1 - Knicker, Axel J. A1 - Albracht, Kirsten T1 - Increased shoulder muscle stretch reflex elicitability in supine subject posture JF - Isokinetics and Exercise Science N2 - BACKGROUND: Muscle stretch reflexes are widely used to examine neural muscle function. The knowledge of reflex response in muscles crossing the shoulder is limited. OBJECTIVE: To quantify reflex modulation according to various subject postures and different procedures of muscle pre-activation steering. METHODS: Thirteen healthy male participants performed two sets of external shoulder rotation stretches in various positions and with different procedures of muscle pre-activation steering on an isokinetic dynamometer over a range of two different pre-activation levels. All stretches were applied with a dynamometer acceleration of 104∘/s2 and a velocity of 150∘/s. Electromyographical response was measured via sEMG. RESULTS: Consistent reflexive response was observed in all tested muscles in all experimental conditions. The reflex elicitation rate revealed a significant muscle main effect (F (5,288) = 2.358, ρ= 0.040; η2= 0.039; f= 0.637) and a significant test condition main effect (F (1,288) = 5.884, ρ= 0.016; η2= 0.020; f= 0.143). Reflex latency revealed a significant muscle pre-activation level main effect (F (1,274) = 5.008, ρ= 0.026; η2= 0.018; f= 0.469). CONCLUSION: Muscular reflexive response was more consistent in the primary internal rotators of the shoulder. Supine posture in combination with visual feedback of muscle pre-activation level enhanced the reflex elicitation rate. Y1 - 2020 U6 - https://doi.org/10.3233/IES-192219 SN - 1878-5913 VL - 28 IS - 2 SP - 139 EP - 146 PB - IOS Press CY - Amsterdam ER - TY - JOUR A1 - Schiedermeier, Maximilian A1 - Rettner, Cornelius A1 - Heilmann, Marcel A1 - Schneider, Felix A1 - Marz, Martin T1 - Interference of automotive HV-DC-systems by traction voltage-source-inverters (VSI) JF - 2019 IEEE Transportation Electrification Conference (ITEC-India) Y1 - 2019 U6 - https://doi.org/10.1109/ITEC-India48457.2019.ITECINDIA2019-37 SP - 1 EP - 6 PB - IEEE CY - New York ER - TY - JOUR A1 - Hoeveler, B. A1 - Bauknecht, André A1 - Wolf, C. Christian A1 - Janser, Frank T1 - Wind-Tunnel Study of a Wing-Embedded Lifting Fan Remaining Open in Cruise Flight JF - Journal of Aircraft N2 - It is investigated whether a nonrotating lifting fan remaining uncovered during cruise flight, as opposed to being covered by a shutter system, can be realized with limited additional drag and loss of lift during cruise flight. A wind-tunnel study of a wing-embedded lifting fan has been conducted at the Side Wind Test Facility Göttingen of DLR, German Aerospace Center in Göttingen using force, pressure, and stereoscopic particle image velocimetry techniques. The study showed that a step on the lower side of the wing in front of the lifting fan duct increases the lift-to-drag ratio of the whole model by up to 25% for all positive angles of attack. Different sizes and inclinations of the step had limited influence on the surface pressure distribution. The data indicate that these parameters can be optimized to maximize the lift-to-drag ratio. A doubling of the curvature radius of the lifting fan duct inlet lip on the upper side of the wing affected the lift-to-drag ratio by less than 1%. The lifting fan duct inlet curvature can therefore be optimized to maximize the vertical fan thrust of the rotating lifting fan during hovering without affecting the cruise flight performance with a nonrotating fan. Y1 - 2020 U6 - https://doi.org/10.2514/1.C035422 SN - 1533-3868 VL - 57 IS - 4 PB - AIAA CY - Reston, Va. ER - TY - JOUR A1 - Choi, Chang-Hoon A1 - Felder, Tim A1 - Felder, Jörg A1 - Tellmann, Lutz A1 - Hong, Suk-Min A1 - Wegener, Hans-Peter A1 - Shah, N Jon A1 - Ziemons, Karl T1 - Design, evaluation and comparison of endorectal coils for hybrid MR-PET imaging of the prostate JF - Physics in Medicine & Biology N2 - Prostate cancer is one of the most common cancers among men and its early detection is critical for its successful treatment. The use of multimodal imaging, such as MR-PET, is most advantageous as it is able to provide detailed information about the prostate. However, as the human prostate is flexible and can move into different positions under external conditions, it is important to localise the focused region-of-interest using both MRI and PET under identical circumstances. In this work, we designed five commonly used linear and quadrature radiofrequency surface coils suitable for hybrid MR-PET use in endorectal applications. Due to the endorectal design and the shielded PET insert, the outer face of the coils investigated was curved and the region to be imaged was outside the volume of the coil. The tilting angles of the coils were varied with respect to the main magnetic field direction. This was done to approximate the various positions from which the prostate could be imaged. The transmit efficiencies and safety excitation efficiencies from simulations, together with the signal-to-noise ratios from the MR images were calculated and analysed. Overall, it was found that the overlapped loops driven in quadrature were superior to the other types of coils we tested. In order to determine the effect of the different coil designs on PET, transmission scans were carried out, and it was observed that the differences between attenuation maps with and without the coils were negligible. The findings of this work can provide useful guidance for the integration of such coil designs into MR-PET hybrid systems in the future. Y1 - 2020 U6 - https://doi.org/10.1088/1361-6560/ab87f8 SN - 0031-9155 VL - 65 IS - 11 PB - IOP CY - Bristol ER - TY - JOUR A1 - Khayyam, Hamid A1 - Jamali, Ali A1 - Bab-Hadiashar, Alireza A1 - Esch, Thomas A1 - Ramakrishna, Seeram A1 - Jalili, Mahdi A1 - Naebe, Minoo T1 - A Novel Hybrid Machine Learning Algorithm for Limited and Big Data Modeling with Application in Industry 4.0 JF - IEEE Access N2 - To meet the challenges of manufacturing smart products, the manufacturing plants have been radically changed to become smart factories underpinned by industry 4.0 technologies. The transformation is assisted by employment of machine learning techniques that can deal with modeling both big or limited data. This manuscript reviews these concepts and present a case study that demonstrates the use of a novel intelligent hybrid algorithms for Industry 4.0 applications with limited data. In particular, an intelligent algorithm is proposed for robust data modeling of nonlinear systems based on input-output data. In our approach, a novel hybrid data-driven combining the Group-Method of Data-Handling and Singular-Value Decomposition is adapted to find an offline deterministic model combined with Pareto multi-objective optimization to overcome the overfitting issue. An Unscented-Kalman-Filter is also incorporated to update the coefficient of the deterministic model and increase its robustness against data uncertainties. The effectiveness of the proposed method is examined on a set of real industrial measurements. Y1 - 2020 U6 - https://doi.org/10.1109/ACCESS.2020.2999898 SN - 2169-3536 VL - 8 IS - Art. 9108222 SP - 111381 EP - 111393 PB - IEEE CY - New York, NY ER - TY - CHAP A1 - Braun, Sebastian A1 - Cheng, Chi-Tsun A1 - Dowey, Steve A1 - Wollert, Jörg T1 - Survey on Security Concepts to Adapt Flexible Manufacturing and Operations Management based upon Multi-Agent Systems T2 - 2020 IEEE 29th International Symposium on Industrial Electronics (ISIE), Proceedings N2 - The increasing digitalization brings new opportunities but also puts new challenges to modern industrial systems. Software agents are one of the key technologies towards self-optimizing factories and are currently used to address the needs of cyber-physical production systems (CPPS). However their interplay in industrial settings needs to be understood better.This paper focusses on securing a cloud infrastructure for multi-agent systems for industrial sites. An industrial site contains multiple production processes that need to communicate with each other and each physical resource is abstracted with a software agent. This volatile architecture needs to be managed and protected from manipulation. The proposed infrastructure presents a security concept for TCP/IP communication between agents, machines, and external networks. It is based on open-source software and tested on a three-node edge cloud controlling a model-plant. Y1 - 2020 U6 - https://doi.org/10.1109/ISIE45063.2020.9152210 N1 - 2020 IEEE 29th International Symposium on Industrial Electronics (ISIE), 17 - 19 June, 2020, Delft, Netherlands PB - IEEE CY - New York, NY ER - TY - JOUR A1 - Gronsfeld, Richard A1 - Joachim, Klubert A1 - Malecha, Hartmut T1 - 3-D-Visualisierung von vorhandenen Staubauwerken zur holistischen Planung und Überwachung JF - Wasserwirtschaft Y1 - 2019 U6 - https://doi.org/10.1007/s35147-019-0075-x SN - 2192-8762 N1 - gedruckt in der Bereichsbibliothek Bayernallee unter der Signatur 13 Z 218 vorhanden VL - 109 IS - 5 SP - 82 EP - 85 PB - Springer CY - Berlin ER - TY - JOUR A1 - Svaneborg, Carsten A1 - Karimi-Varzaneh, Hossein Ali A1 - Hojdis, Nils A1 - Fleck, Franz A1 - Everaers, Ralf T1 - Multiscale approach to equilibrating model polymer melts JF - Physical Review E N2 - We present an effective and simple multiscale method for equilibrating Kremer Grest model polymer melts of varying stiffness. In our approach, we progressively equilibrate the melt structure above the tube scale, inside the tube and finally at the monomeric scale. We make use of models designed to be computationally effective at each scale. Density fluctuations in the melt structure above the tube scale are minimized through a Monte Carlo simulated annealing of a lattice polymer model. Subsequently the melt structure below the tube scale is equilibrated via the Rouse dynamics of a force-capped Kremer-Grest model that allows chains to partially interpenetrate. Finally the Kremer-Grest force field is introduced to freeze the topological state and enforce correct monomer packing. We generate 15 melts of 500 chains of 10.000 beads for varying chain stiffness as well as a number of melts with 1.000 chains of 15.000 monomers. To validate the equilibration process we study the time evolution of bulk, collective, and single-chain observables at the monomeric, mesoscopic, and macroscopic length scales. Extension of the present method to longer, branched, or polydisperse chains, and/or larger system sizes is straightforward. Y1 - 2016 U6 - https://doi.org/10.1103/PhysRevE.94.032502 SN - 2470-0053 VL - 94 IS - 032502 PB - AIP Publishing CY - Melville, NY ER - TY - JOUR A1 - Schwab, Lukas A1 - Hojdis, Nils A1 - Lacayo, Jorge A1 - Wilhelm, Manfred T1 - Fourier-Transform Rheology of Unvulcanized, Carbon Black Filled Styrene Butadiene Rubber JF - Macromolecular Materials and Engineering N2 - Rubber materials filled with reinforcing fillers display nonlinear rheological behavior at small strain amplitudes below γ0 < 0.1. Nevertheless, rheological data are analyzed mostly in terms of linear parameters, such as shear moduli (G′, G″), which loose their physical meaning in the nonlinear regime. In this work styrene butadiene rubber filled with carbon black (CB) under large amplitude oscillatory shear (LAOS) is analyzed in terms of the nonlinear parameter I3/1. Three different CB grades are used and the filler load is varied between 0 and 70 phr. It is found that I3/1(φ) is most sensitive to changes of the total accessible filler surface area at low strain amplitudes (γ0 = 0.32). The addition of up to 70 phr CB leads to an increase of I3/1(φ) by a factor of more than ten. The influence of the measurement temperature on I3/1 is pronounced for CB levels above the percolation threshold. Y1 - 2016 U6 - https://doi.org/10.1002/mame.201500356 SN - 1439-2054 VL - 301 IS - 4 SP - 457 EP - 468 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Harish, Ajay B. A1 - Wriggers, Peter A1 - Jungk, Juliane A1 - Hojdis, Nils A1 - Recker, Carla T1 - Mesoscale Constitutive Modeling of Non-Crystallizing Filled Elastomers JF - Computational Mechanics N2 - Elastomers are exceptional materials owing to their ability to undergo large deformations before failure. However, due to their very low stiffness, they are not always suitable for industrial applications. Addition of filler particles provides reinforcing effects and thus enhances the material properties that render them more versatile for applications like tyres etc. However, deformation behavior of filled polymers is accompanied by several nonlinear effects like Mullins and Payne effect. To this day, the physical and chemical changes resulting in such nonlinear effect remain an active area of research. In this work, we develop a heterogeneous (or multiphase) constitutive model at the mesoscale explicitly considering filler particle aggregates, elastomeric matrix and their mechanical interaction through an approximate interface layer. The developed constitutive model is used to demonstrate cluster breakage, also, as one of the possible sources for Mullins effect observed in non-crystallizing filled elastomers. Y1 - 2016 U6 - https://doi.org/10.1007/s00466-015-1251-1 SN - 1432-0924 VL - 57 SP - 653 EP - 677 PB - Springer CY - Berlin ER - TY - JOUR A1 - Hentschke, Reinhard A1 - Hager, Jonathan A1 - Hojdis, Nils T1 - Molecular Modeling Approach to the Prediction of Mechanical Properties of Silica-Reinforced Rubbers JF - Journal of Applied Polymer Science N2 - Recently, we have suggested a nanomechanical model for dissipative loss in filled elastomer networks in the context of the Payne effect. The mechanism is based on a total interfiller particle force exhibiting an intermittent loop, due to the combination of short-range repulsion and dispersion forces with a long-range elastic attraction. The sum of these forces leads, under external strain, to a spontaneous instability of “bonds” between the aggregates in a filler network and attendant energy dissipation. Here, we use molecular dynamics simulations to obtain chemically realistic forces between surface modified silica particles. The latter are combined with the above model to estimate the loss modulus and the low strain storage modulus in elastomers containing the aforementioned filler-compatibilizer systems. The model is compared to experimental dynamic moduli of silica filled rubbers. We find good agreement between the model predictions and the experiments as function of the compatibilizer's molecular structure and its bulk concentration. KW - theory and modeling KW - supramolecular structures KW - rubber KW - mechanical properties KW - elastomers Y1 - 2014 U6 - https://doi.org/10.1002/app.40806 SN - 1097-4628 VL - 131 IS - 18 SP - 1 EP - 9 PB - Wiley CY - New York, NY ER - TY - PAT A1 - Finger, Sebastian A1 - Hojdis, Nils A1 - Menglong, Huang T1 - Sekundäre galvanische Zelle N2 - Die vorliegende Erfindung betrifft eine sekundäre galvanische Zelle, umfassend eine Kathode, eine Anode und einen Separator, der zwischen der Kathode und der Anode angeordnet ist, wobei die Kathode ein erstes elastomeres Polymer umfasst, welches mit einem ersten Füllstoff als Kathodenmaterial gefüllt ist, wobei die Anode ein zweites elastomeres Polymer umfasst, welches mit einem zweiten Füllstoff als Anodenmaterial gefüllt ist, wobei der Separator ein drittes elastomeres Polymer umfasst, wobei das erste elastomere Polymer, das zweite elastomere Polymer und das dritte elastomere Polymer unabhängig voneinander aus vernetzungsfähigen Dienkautschuken ausgewählt sind, und wobei zumindest eines von dem ersten elastomeren Polymer, dem zweiten elastomeren Polymer und dem dritten elastomeren Polymer eine ionische Flüssigkeit und/oder ein elektrisch leitfähiges Polymer enthält. Die vorliegende Erfindung betrifft ferner eine wiederaufladbare Batterie, umfassend die erfindungsgemäße sekundäre galvanische Zelle, ein Verfahren zur Herstellung einer sekundären galvanischen Zelle sowie die Verwendung der erfindungsgemäßen sekundären galvanischen Zelle sowie der erfindungsgemäßen wiederaufladbaren Batterie. Y1 - 2020 N1 - Patent DE102018222385A1 25.06.2020 auch veröffentlicht unter EP3671932A1 ER - TY - PAT A1 - Hojdis, Nils A1 - Recker, Carla T1 - Schwefelvernetzte Kautschukmischung für Fahrzeugreifen enthaltend Carbon Nanotubes (cnt), Fahrzeugreifen, Der Die schwefelvernetzte Kautschukmischung aufweist, sowie Verfahren zur Herstellung der schwefelvernetzten Kautschukmischung enthaltend Cnt Y1 - 2020 N1 - Patent EP000003625288A1 25.03.2020 auch veröffentlicht unter CN110678508A; DE102017208137A1; WO2018210471A1 ER - TY - PAT A1 - Ehmke, Tobias A1 - Finger, Sebastian A1 - Hojdis, Nils A1 - Kurz, Martin A1 - Nawrocka-Herczynska, Monika T1 - Funkeinheit und Vorrichtung mit einer Funkeinheit N2 - Dargestellt und beansprucht ist eine Funkeinheit mit einem Funkbauteil, einer elektrisch leitfähigen Antenne und einem Kunststoffverbindungsmittel. Das Funkbauteil weist einen Antennenanschluss auf. Das Kunststoffverbindungsmittel weist ein erstes Elastomermaterial mit elektrisch leitfähigem Zusatzmaterial auf, so dass das Kunststoffverbindungsmittel elektrisch leitfähig ist. Das Kunststoffverbindungsmittel bildet eine mechanische und elektrisch leitfähige Verbindung zwischen dem Antennenanschluss und der Antenne. Weiterhin wird eine Vorrichtung mit einem ein Matrixmaterial mit oder aus einem zweiten Elastomermaterial und einer Funkeinheit beschrieben und beansprucht, wobei die Funkeinheit vollständig in das Matrixmaterial eingebettet ist. Die Vorrichtung kann insbesondere ein Fahrzeugreifen sein. Y1 - 2020 N1 - Patent DE102018222380A1 25.06.2020 ER - TY - PAT A1 - Hojdis, Nils T1 - Verfahren zum Bestimmen einer Sitzeinstellung eines Sitzes eines Kraftfahrzeugs, Computerprogrammprodukt, Servereinrichtung, Kommunikationsendgerät und Kraftfahrzeug N2 - Die Erfindung betrifft ein Verfahren zum Bestimmen einer Sitzeinstellung (23) eines Sitzes (3) eines Kraftfahrzeugs (1), bei welchem folgende Schritte durchgeführt werden:- Bereitstellen einer Körperabmessung (12) eines Nutzers (6) des Kraftfahrzeugs (1);- Bereitstellen einer Sitzeigenschaft (13) des Sitzes (3) des Kraftfahrzeugs (1);- Bereitstellen eines mit zumindest einer Referenzsitzeigenschaft (20), zumindest einer Referenzkörperabmessung (21) und zumindest einer Referenzsitzeinstellung (22) trainiertes künstliches neuronales Netz (14); und- Bestimmen der Sitzeinstellung (23) durch Eingabe der Körperabmessung (12) und der Sitzeigenschaft (13) in das künstliche neuronale Netz (14). Y1 - 2019 N1 - Patent DE102018211831A1 05.12.2019 ER - TY - PAT A1 - Dauer, David-Raphael A1 - Hojdis, Nils A1 - Müller, Norbert A1 - Recker, Carla A1 - Schax, Fabian A1 - Schöffel, Julia A1 - Tarantola, Gesa A1 - Weber, Christine T1 - Schwefelvernetzbare Kautschukmischung, Vulkanisat der Kautschukmischung und Fahrzeugreifen N2 - Die Erfindung betrifft eine schwefelvernetzbare Kautschukmischung, deren Vulkanisat und einen Fahrzeugreifen.Die schwefelvernetzbare Kautschukmischung enthält wenigstens die folgenden Bestandteile:- wenigstens einen Dienkautschuk; und- 10 bis 300 phr wenigstens einer Kieselsäure ; und- 1 bis 30 phf wenigstens eines Silans A mit der allgemeinen Summenformel A-I)und- 0,5 bis 30 phf wenigstens eines Silans B mit der allgemeinen Summenformel B-I)wobei u gleich 0, 1, 2 oder 3 und v gleich 0 oder 1 ist. Y1 - 2019 N1 - Patent DE102017221236A1 29.05.2019 auch veröffentlicht unter CN111405987A; TW201925305A; WO2019105615A1 ER - TY - JOUR A1 - Kuhnhenne, Markus A1 - Reger, Vitali A1 - Pyschny, Dominik A1 - Döring, Bernd T1 - Influence of airtightness of steel sandwich panel joints on heat losses JF - E3S Web of Conferences 12th Nordic Symposium on Building Physics (NSB 2020) N2 - Energy saving ordinances requires that buildings must be designed in such a way that the heat transfer surface including the joints is permanently air impermeable. The prefabricated roof and wall panels in lightweight steel constructions are airtight in the area of the steel covering layers. The sealing of the panel joints contributes to fulfil the comprehensive requirements for an airtight building envelope. To improve the airtightness of steel sandwich panels, additional sealing tapes can be installed in the panel joint. The influence of these sealing tapes was evaluated by measurements carried out by the RWTH Aachen University - Sustainable Metal Building Envelopes. Different installation situations were evaluated by carrying out airtightness tests for different joint distances. In addition, the influence on the heat transfer coefficient was also evaluated using the Finite Element Method (FEM). The combination of obtained air volume flow and transmission losses enables to create an "effective heat transfer coefficient" due to transmission and infiltration. This summarizes both effects in one value and is particularly helpful for approximate calculations on energy efficiency. Y1 - 2020 U6 - https://doi.org/10.1051/e3sconf/202017205008 VL - 172 IS - Art. 05008 PB - EDP Sciences CY - Les Ulis ER - TY - JOUR A1 - Kunkel, Maximilian Hugo A1 - Gebhardt, Andreas A1 - Mpofu, Khumbulani A1 - Kallweit, Stephan T1 - Quality assurance in metal powder bed fusion via deep-learning-based image classification JF - Rapid Prototyping Journal Y1 - 2019 U6 - https://doi.org/10.1108/RPJ-03-2019-0066 SN - 1355-2546 VL - 26 IS - 2 SP - 259 EP - 266 ER - TY - JOUR A1 - Maurischat, Andreas A1 - Perkins, Rudolph T1 - Taylor coefficients of Anderson generating functions and Drinfeld torsion extensions N2 - We generalize our work on Carlitz prime power torsion extension to torsion extensions of Drinfeld modules of arbitrary rank. As in the Carlitz case, we give a description of these extensions in terms of evaluations of Anderson generating functions and their hyperderivatives at roots of unity. We also give a direct proof that the image of the Galois representation attached to the p-adic Tate module lies in the p-adic points of the motivic Galois group. This is a generalization of the corresponding result of Chang and Papanikolas for the t-adic case. Y1 - 2020 U6 - https://doi.org/10.1142/S1793042122500099 IS - Vol. 18, No. 01 SP - 113 EP - 130 PB - World Scientific CY - Singapur ER - TY - JOUR A1 - El Moussaoui, Noureddine A1 - Talbi, Sofian A1 - Atmane, Ilyas A1 - Kassmi, Khalil A1 - Schwarzer, Klemens A1 - Chayeb, Hamid A1 - Bachiri, Najib T1 - Feasibility of a new design of a Parabolic Trough Solar Thermal Cooker (PSTC) JF - Solar Energy N2 - In this article, we describe the structure, the functioning, and the tests of parabolic trough solar thermal cooker (PSTC). This oven is designed to meet the needs of rural residents, including Urban, which requires stable cooking temperatures above 200 °C. The cooking by this cooker is based on the concentration of the sun's rays on a glass vacuum tube and heating of the oil circulate in a big tube, located inside the glass tube. Through two small tubes, associated with large tube, the heated oil, rise and heats the pot of cooking pot containing the food to be cooked (capacity of 5 kg). This cooker is designed in Germany and extensively tested in Morocco for use by the inhabitants who use wood from forests. During a sunny day, having a maximum solar radiation around 720 W/m2 and temperature ambient around 26 °C, maximum temperatures recorded of the small tube, the large tube and the center of the pot are respectively: 370 °C, 270 °C and 260 °C. The cooking process with food at high (fries, ..), we show that the cooking oil temperature rises to 200 °C, after 1 h of heating, the cooking is done at a temperature of 120 °C for 20 min. These temperatures are practically stable following variations and decreases in the intensity of irradiance during the day. The comparison of these results with those of the literature shows an improvement of 30–50 % on the maximum value of the temperature with a heat storage that could reach 60 min of autonomy. All the results obtained show the good functioning of the PSTC and the feasibility of cooking food at high temperature (>200 °C). Y1 - 2020 U6 - https://doi.org/10.1016/j.solener.2020.03.079 SN - 0038-092X VL - 201 IS - Vol. 201 (May 2020) SP - 866 EP - 871 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Müller, Wolfram A1 - Jung, Alexander A1 - Ahammer, Helmut T1 - Advantages and problems of nonlinear methods applied to analyze physiological time signals: human balance control as an example JF - Scientific Reports Y1 - 2017 SN - 2045-2322 U6 - https://doi.org/10.1038/s41598-017-02665-5 VL - 7 IS - Article number 2464 SP - 1 EP - 11 PB - Springer Nature CY - Cham ER - TY - JOUR A1 - Orzada, Stephan A1 - Fiedler, Thomas M. A1 - Bitz, Andreas A1 - Ladd, Mark E. A1 - Quick, Harald H. T1 - Local SAR compression with overestimation control to reduce maximum relative SAR overestimation and improve multi-channel RF array performance JF - Magnetic Resonance Materials in Physics, Biology and Medicine N2 - Objective In local SAR compression algorithms, the overestimation is generally not linearly dependent on actual local SAR. This can lead to large relative overestimation at low actual SAR values, unnecessarily constraining transmit array performance. Method Two strategies are proposed to reduce maximum relative overestimation for a given number of VOPs. The first strategy uses an overestimation matrix that roughly approximates actual local SAR; the second strategy uses a small set of pre-calculated VOPs as the overestimation term for the compression. Result Comparison with a previous method shows that for a given maximum relative overestimation the number of VOPs can be reduced by around 20% at the cost of a higher absolute overestimation at high actual local SAR values. Conclusion The proposed strategies outperform a previously published strategy and can improve the SAR compression where maximum relative overestimation constrains the performance of parallel transmission. Y1 - 2020 SN - 1352-8661 U6 - https://doi.org/10.1007/s10334-020-00890-0 IS - 34 (2021) SP - 153 EP - 164 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Ulmer, Jessica A1 - Braun, Sebastian A1 - Cheng, Chi-Tsun A1 - Dowey, Steve A1 - Wollert, Jörg T1 - Human-Centered Gamification Framework for Manufacturing Systems JF - Procedia CIRP N2 - While bringing new opportunities, the Industry 4.0 movement also imposes new challenges to the manufacturing industry and all its stakeholders. In this competitive environment, a skilled and engaged workforce is a key to success. Gamification can generate valuable feedbacks for improving employees’ engagement and performance. Currently, Gamification in workspaces focuses on computer-based assignments and training, while tasks that require manual labor are rarely considered. This research provides an overview of Enterprise Gamification approaches and evaluates the challenges. Based on that, a skill-based Gamification framework for manual tasks is proposed, and a case study in the Industry 4.0 model factory is shown. Y1 - 2020 U6 - https://doi.org/10.1016/j.procir.2020.04.076 SN - 2212-8271 VL - 93 SP - 670 EP - 675 PB - Elsevier CY - Amsterdam ER - TY - CHAP A1 - Uibel, Thomas A1 - Moorkamp, Wilfried T1 - Geh- und Radwegbrücken in NRW - Bestandsanalyse und Perspektiven T2 - Holzbrückenbau in der Offensive : Erhaltung, Ertüchtigung, Neubauten : 5. Internationale Holzbrückentage (IHB 2018) FILharmonie Filderstadt, Filderstadt/Stuttgart (DE), 17./18. April 2018 Y1 - 2018 SN - 978-3-906226-19-4 SP - 19 EP - 32 PB - forum-holzbau CY - Biel ER - TY - CHAP A1 - Jockwer, R. A1 - Kleiber, M. A1 - Uibel, Thomas ED - Görlacher, Rainer T1 - Criteria for Evaluating the Simplification of Design Rules for Dowel-type Fasteners T2 - International Network on Timber Engineering Research, INTER : proceedings, meeting 51, 10 - 13 August 2016, Tallinn, Estonia Y1 - 2018 SP - 461 EP - 466 PB - Timber Scientific Publishing, KIT Holzbau und Baukonstruktionen CY - Karlsruhe ER - TY - CHAP A1 - Bedbur, Christian A1 - Thull, J. A1 - Moorkamp, Wilfried A1 - Uibel, Thomas T1 - Standardbrücken für Geh- und Radwege T2 - Tagungsband 4. Aachener Holzbautagung 2019: 12. und 13. September an der FH Aachen Y1 - 2020 SN - 2197-4489 SP - 34 EP - 45 PB - FH Aachen CY - Aachen ER - TY - JOUR A1 - Everaers, Ralf A1 - Karimi-Varzaneh, Hossein Ali A1 - Fleck, Franz A1 - Hojdis, Nils A1 - Svaneborg, Carsten T1 - Kremer–Grest Models for Commodity Polymer Melts: Linking Theory, Experiment, and Simulation at the Kuhn Scale JF - Macromolecules N2 - The Kremer–Grest (KG) polymer model is a standard model for studying generic polymer properties in molecular dynamics simulations. It owes its popularity to its simplicity and computational efficiency, rather than its ability to represent specific polymers species and conditions. Here we show that by tuning the chain stiffness it is possible to adapt the KG model to model melts of real polymers. In particular, we provide mapping relations from KG to SI units for a wide range of commodity polymers. The connection between the experimental and the KG melts is made at the Kuhn scale, i.e., at the crossover from the chemistry-specific small scale to the universal large scale behavior. We expect Kuhn scale-mapped KG models to faithfully represent universal properties dominated by the large scale conformational statistics and dynamics of flexible polymers. In particular, we observe very good agreement between entanglement moduli of our KG models and the experimental moduli of the target polymers. Y1 - 2020 U6 - https://doi.org/10.1021/acs.macromol.9b02428 SN - 1520-5835 VL - 53 IS - 6 SP - 1901 EP - 1916 PB - ACS Publications CY - Washington, DC ER - TY - JOUR A1 - Meyer, Jan A1 - Hentschke, Reinhard A1 - Hager, Jonathan A1 - Hojdis, Nils A1 - Karimi-Varzaneh, Hossein Ali T1 - Molecular Simulation of Viscous Dissipation due to Cyclic Deformation of a Silica–Silica Contact in Filled Rubber JF - Macromolecules Y1 - 2017 U6 - https://doi.org/10.1021/acs.macromol.7b00947 SN - 1520-5835 VL - 50 IS - 17 SP - 6679 EP - 6689 ER - TY - JOUR A1 - Hager, Jonathan A1 - Hentschke, Reinhard A1 - Hojdis, Nils A1 - Karimi-Varzaneh, Hossein Ali T1 - Computer Simulation of Particle–Particle Interaction in a Model Polymer Nanocomposite JF - Macromolecules Y1 - 2015 U6 - https://doi.org/10.1021/acs.macromol.5b01864 SN - 1520-5835 VL - 48 IS - 24 SP - 9039 EP - 9049 ER - TY - JOUR A1 - Waller, Mark P. A1 - Braun, Heiko A1 - Hojdis, Nils A1 - Bühl, Michael T1 - Geometries of Second-Row Transition-Metal Complexes from Density-Functional Theory JF - Journal of Chemical Theory and Computation Y1 - 2007 U6 - https://doi.org/10.1021/ct700178y SN - 1549-9626 VL - 3 IS - 6 SP - 2234 EP - 2242 ER - TY - JOUR A1 - Svaneborg, Carsten A1 - Karimi-Varzaneh, Hossein Ali A1 - Hojdis, Nils A1 - Fleck, Franz A1 - Everaers, Ralf T1 - Kremer-Grest Models for Universal Properties of Specific Common Polymer Species JF - Soft Condensed Matter N2 - The Kremer-Grest (KG) bead-spring model is a near standard in Molecular Dynamic simulations of generic polymer properties. It owes its popularity to its computational efficiency, rather than its ability to represent specific polymer species and conditions. Here we investigate how to adapt the model to match the universal properties of a wide range of chemical polymers species. For this purpose we vary a single parameter originally introduced by Faller and Müller-Plathe, the chain stiffness. Examples include polystyrene, polyethylene, polypropylene, cis-polyisoprene, polydimethylsiloxane, polyethyleneoxide and styrene-butadiene rubber. We do this by matching the number of Kuhn segments per chain and the number of Kuhn segments per cubic Kuhn volume for the polymer species and for the Kremer-Grest model. We also derive mapping relations for converting KG model units back to physical units, in particular we obtain the entanglement time for the KG model as function of stiffness allowing for a time mapping. To test these relations, we generate large equilibrated well entangled polymer melts, and measure the entanglement moduli using a static primitive-path analysis of the entangled melt structure as well as by simulations of step-strain deformation of the model melts. The obtained moduli for our model polymer melts are in good agreement with the experimentally expected moduli. Y1 - 2018 IS - 1606.05008 ER - TY - JOUR A1 - Mayer, Jan A1 - Hentschke, Reinhard A1 - Hager, Jonathan A1 - Hojdis, Nils A1 - Karimi-Varnaneh, Hossein Ali T1 - A Nano-Mechanical Instability as Primary Contribution to Rolling Resistance JF - Scientific Reports Y1 - 2017 SN - 2045-2322 VL - 7 IS - Article number 11275 PB - Springer CY - Berlin ER - TY - THES A1 - Dahmen-Beumers, Judith T1 - Eine exemplarische Untersuchung zur Regionalität in der Kunst : der Aachener Bildhauer und Maler Benno Werth (*1929) KW - Kunstmarkt KW - Geschichte KW - Aachen Y1 - 2005 SN - 3-8334-3014-1 SN - 9783833430145 PB - Books on Demand CY - Norderstedt ER - TY - CHAP A1 - Wiegner, Jonas A1 - Volker, Hanno A1 - Mainz, Fabian A1 - Backes, Andreas A1 - Löken, Michael A1 - Hüning, Felix T1 - Wiegand-effect-powered wireless IoT sensor node T2 - ITG-Fb. 303: Sensoren und Messsysteme N2 - In this article we describe an Internet-of-Things sensing device with a wireless interface which is powered by the oftenoverlooked harvesting method of the Wiegand effect. The sensor can determine position, temperature or other resistively measurable quantities and can transmit the data via an ultra-low power ultra-wideband (UWB) data transmitter. With this approach we can energy-self-sufficiently acquire, process, and wirelessly transmit data in a pulsed operation. A proof-of-concept system was built up to prove the feasibility of the approach. The energy consumption of the system is analyzed and traced back in detail to the individual components, compared to the generated energy and processed to identify further optimization options. Based on the proof-of-concept, an application demonstrator was developed. Finally, we point out possible use cases. Y1 - 2022 SN - 978-3-8007-5835-7 N1 - Sensoren und Messsysteme - 21. ITG/GMA-Fachtagung, 10.05.2022 - 11.05.2022 in Nürnberg SP - 255 EP - 260 PB - VDE Verlag GmbH CY - Berlin ER - TY - JOUR A1 - Ulmer, Jessica A1 - Braun, Sebastian A1 - Cheng, Chi-Tsun A1 - Dowey, Steve A1 - Wollert, Jörg T1 - Gamification of virtual reality assembly training: Effects of a combined point and level system on motivation and training results JF - International Journal of Human-Computer Studies N2 - Virtual Reality (VR) offers novel possibilities for remote training regardless of the availability of the actual equipment, the presence of specialists, and the training locations. Research shows that training environments that adapt to users' preferences and performance can promote more effective learning. However, the observed results can hardly be traced back to specific adaptive measures but the whole new training approach. This study analyzes the effects of a combined point and leveling VR-based gamification system on assembly training targeting specific training outcomes and users' motivations. The Gamified-VR-Group with 26 subjects received the gamified training, and the Non-Gamified-VR-Group with 27 subjects received the alternative without gamified elements. Both groups conducted their VR training at least three times before assembling the actual structure. The study found that a level system that gradually increases the difficulty and error probability in VR can significantly lower real-world error rates, self-corrections, and support usages. According to our study, a high error occurrence at the highest training level reduced the Gamified-VR-Group's feeling of competence compared to the Non-Gamified-VR-Group, but at the same time also led to lower error probabilities in real-life. It is concluded that a level system with a variable task difficulty should be combined with carefully balanced positive and negative feedback messages. This way, better learning results, and an improved self-evaluation can be achieved while not causing significant impacts on the participants' feeling of competence. KW - Gamification KW - Virtual reality KW - Assembly KW - User study KW - Level system Y1 - 2022 U6 - https://doi.org/10.1016/j.ijhcs.2022.102854 SN - 1071-5819 VL - 165 IS - Art. No. 102854 PB - Elsevier CY - Amsterdam ER - TY - THES A1 - Schnitzler, Nora T1 - Identifikation und Bewertung geeigneter Mikrostrukturierungen zum Schutz von Biohybridbeschichtungen von Zahnimplantaten vor Abrasion beim Zähneputzen N2 - Die Oberflächen dentaler Implantate sind definiert durch eine raue Oberfläche, um die Integration in den menschlichen Knochen zu optimieren. Entzündungen des umgebenden Zahnfleisches zählen dabei zu den häufigsten Komplikationen nach einer Implantation. Diese Entzündungen entstehen hauptsächlich durch bakterielle Infektionen des Weichgewebes an der Implantations-Stelle. Die raue Oberfläche trägt jedoch zu einer solchen Infektion bei. Da der Implantat-Kopf zum Teil aus dem Knochen herausragt, erfolgt beispielsweise beim Zähneputzen eine Freilegung der Implantat-Oberfläche. Die durch die Rauheit vergrößerte Oberfläche bietet dabei ideale Voraussetzungen für eine Bakterienansiedlung. In der aktuellen Forschung steht die Entwicklung einer Oberfläche im Vordergrund, die eine antibakterielle Funktionalisierung erzeugt. Diese verhindert die Bakterienansiedlung und wirkt einer Entzündung entgegen. Um die Beschichtung vor Verschleiß zu schützen und ihre Lebensdauer der antibakteriellen Wirkung zu erhöhen, ist es möglich die Oberfläche mit einer Mikrostruktur zu versehen. Das Ziel der vorliegenden Arbeit ist die Identifikation geeigneter Mikrostrukturierungen, die der antibakteriellen Beschichtung einen optimalen Schutz vor Verschleiß bieten. Am Beispiel von Titan-Zahnimplantaten wird der Schutz der aufgetragenen Biohybridbeschichtung gegen abrasiven Verschleiß untersucht. Im Vorfeld wird eine Analyse der fertigungstechnischen Möglichkeiten mit Blick auf dentale Implantate und Mikrostrukturen durchgeführt, um das ein passendes Verfahren zu identifizieren. Die Analogiebauteile als Probenkörper werden, mithilfe des zuvor ausgewählten Verfahrens, mit verschiedenen Mikrostrukturen versehen. Im Rahmen einer Versuchsdurchführung, die die mechanische Belastung bei einem Zahnputzdurchgang imitiert, werden die verschiedenen Mikrostrukturen auf ihre Eignung für diese Anwendung überprüft. Ein Vorversuch dient zur Identifizierung eines geeigneten Ankerpeptids, welches den bindenden Bestandteil der Biohybridbeschichtung darstellt. Aus drei zuvor ausgewählten Ankerpeptiden wird das mit der besten Adhäsionsfähigkeit herausgestellt. Im finalen Versuchsdurchlauf wird das Ankerpeptid auf die Oberflächen, die mit den Mikrostrukturen versehen sind, aufgetragen. Dabei ist das Ziel eine Mikrostruktur herauszustellen, die den höchstmöglichen Schutz bietet. Durch eine Fluoreszenzprüfung mithilfe eines Flourescence Plate Readers wird jede Kombination nach den Belastungsversuchen auf den Restanteil der Beschichtung überprüft. Das Ergebnis stellt eine Mikrostruktur dar, die den bestmöglichen Schutz bietet. Dies ist erkennbar durch den höchsten Anteil an Restbeschichtung. Eine Strukturierung mit sogenannten Micro-Grooves in Kombination mit dem MacHis-Ankerpeptid erzielte in der Analyse der Belastungssimulationen die besten Ergebnisse bezüglich des Schutzes der Beschichtung. Durch die Versuche bestätigte sich eine weitere Annahme. Die Strukturierung der Oberfläche erzielt einen deutlich höheren Schutz im Vergleich zu einer unstrukturierten Oberfläche. Zudem hat sich herausgestellt, dass eine Beschichtung mit dem sogenannten PEO-Verfahren eine deutlich größere Adhäsion der Biohybridbeschichtung erzielt. Dies wird jedoch Thema weiterführender Forschungen sein und kein Bestandteil der vorliegenden Arbeit. Y1 - 2022 PB - FH Aachen CY - Aachen ER - TY - JOUR A1 - Pfaff, Raphael A1 - Enning, Manfred A1 - Sutter, Stefan T1 - A risk‑based approach to automatic brake tests for rail freight service: incident analysis and realisation concept JF - SN Applied Sciences N2 - This study reviews the practice of brake tests in freight railways, which is time consuming and not suitable to detect certain failure types. Public incident reports are analysed to derive a reasonable brake test hardware and communication architecture, which aims to provide automatic brake tests at lower cost than current solutions. The proposed solutions relies exclusively on brake pipe and brake cylinder pressure sensors, a brake release position switch as well as radio communication via standard protocols. The approach is embedded in the Wagon 4.0 concept, which is a holistic approach to a smart freight wagon. The reduction of manual processes yields a strong incentive due to high savings in manual labour and increased productivity. KW - Freight rail KW - Brake test KW - Incident analysis KW - Train composition KW - Brake set-up Y1 - 2022 U6 - https://doi.org/10.1007/s42452-022-05007-x SN - 2523-3971 N1 - Corresponding author: Raphael Pfaff VL - 4 IS - 4 SP - 1 EP - 14 PB - Springer CY - Cham ER - TY - JOUR A1 - Oliveira, Danilo A. A1 - Molinnus, Denise A1 - Beging, Stefan A1 - Siqueira Jr, José R. A1 - Schöning, Michael Josef T1 - Biosensor Based on Self-Assembled Films of Graphene Oxide and Polyaniline Using a Field-Effect Device Platform JF - physica status solidi (a) applications and materials science N2 - A new functionalization method to modify capacitive electrolyte–insulator–semiconductor (EIS) structures with nanofilms is presented. Layers of polyallylamine hydrochloride (PAH) and graphene oxide (GO) with the compound polyaniline:poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (PANI:PAAMPSA) are deposited onto a p-Si/SiO2 chip using the layer-by-layer technique (LbL). Two different enzymes (urease and penicillinase) are separately immobilized on top of a five-bilayer stack of the PAH:GO/PANI:PAAMPSA-modified EIS chip, forming a biosensor for detection of urea and penicillin, respectively. Electrochemical characterization is performed by constant capacitance (ConCap) measurements, and the film morphology is characterized by atomic force microscopy (AFM) and scanning electron microscopy (SEM). An increase in the average sensitivity of the modified biosensors (EIS–nanofilm–enzyme) of around 15% is found in relation to sensors, only carrying the enzyme but without the nanofilm (EIS–enzyme). In this sense, the nanofilm acts as a stable bioreceptor onto the EIS chip improving the output signal in terms of sensitivity and stability. KW - capacitive electrolyte–insulator–semiconductor sensors KW - graphene oxide KW - layer-by-layer technique KW - nanomaterials KW - polyaniline Y1 - 2021 U6 - https://doi.org/10.1002/pssa.202000747 SN - 1862-6319 N1 - Corresponding author: José R. Siqueira Jr & Michael J. Schöning VL - 218 IS - 13 SP - 1 EP - 9 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Welden, Rene A1 - Nagamine Komesu, Cindy A. A1 - Wagner, Patrick H. A1 - Schöning, Michael Josef A1 - Wagner, Torsten T1 - Photoelectrochemical enzymatic penicillin biosensor: A proof-of-concept experiment JF - Electrochemical Science Advances N2 - Photoelectrochemical (PEC) biosensors are a rather novel type of biosensors thatutilizelighttoprovideinformationaboutthecompositionofananalyte,enablinglight-controlled multi-analyte measurements. For enzymatic PEC biosensors,amperometric detection principles are already known in the literature. In con-trast, there is only a little information on H+-ion sensitive PEC biosensors. Inthis work, we demonstrate the detection of H+ions emerged by H+-generatingenzymes, exemplarily demonstrated with penicillinase as a model enzyme on atitanium dioxide photoanode. First, we describe the pH sensitivity of the sensorand study possible photoelectrocatalytic reactions with penicillin. Second, weshow the enzymatic PEC detection of penicillin. KW - enzymatic biosensor KW - penicillin KW - penicillinase KW - photoelectrochemistry KW - titanium dioxide photoanode Y1 - 2021 U6 - https://doi.org/10.1002/elsa.202100131 SN - 2698-5977 N1 - Corresponding author: Michael J. Schöning VL - 2 IS - 4 SP - 1 EP - 5 PB - Wiley-VCH CY - Weinheim ER - TY - JOUR A1 - Richter, Charlotte A1 - Braunstein, Bjoern A1 - Staeudle, Benjamin A1 - Attias, Julia A1 - Suess, Alexander A1 - Weber, Tobias A1 - Mileva, Katya N. A1 - Rittweger, Joern A1 - Green, David A. A1 - Albracht, Kirsten T1 - Contractile behavior of the gastrocnemius medialis muscle during running in simulated hypogravity JF - npj Microgravity N2 - Vigorous exercise countermeasures in microgravity can largely attenuate muscular degeneration, albeit the extent of applied loading is key for the extent of muscle wasting. Running on the International Space Station is usually performed with maximum loads of 70% body weight (0.7 g). However, it has not been investigated how the reduced musculoskeletal loading affects muscle and series elastic element dynamics, and thereby force and power generation. Therefore, this study examined the effects of running on the vertical treadmill facility, a ground-based analog, at simulated 0.7 g on gastrocnemius medialis contractile behavior. The results reveal that fascicle−series elastic element behavior differs between simulated hypogravity and 1 g running. Whilst shorter peak series elastic element lengths at simulated 0.7 g appear to be the result of lower muscular and gravitational forces acting on it, increased fascicle lengths and decreased velocities could not be anticipated, but may inform the development of optimized running training in hypogravity. However, whether the alterations in contractile behavior precipitate musculoskeletal degeneration warrants further study. Y1 - 2021 U6 - https://doi.org/10.1038/s41526-021-00155-7 SN - 2373-8065 N1 - Corresponding author: Charlotte Richter VL - 7 IS - Article number: 32 PB - Springer Nature CY - New York ER - TY - CHAP A1 - Kroniger, Daniel A1 - Horikawa, Atsushi A1 - Funke, Harald A1 - Pfäffle, Franziska T1 - Numerical investigation of micromix hydrogen flames at different combustor pressure levels T2 - The Proceedings of the International Conference on Power Engineering (ICOPE) N2 - This study investigates the influence of pressure on the temperature distribution of the micromix (MMX) hydrogen flame and the NOx emissions. A steady computational fluid dynamic (CFD) analysis is performed by simulating a reactive flow with a detailed chemical reaction model. The numerical analysis is validated based on experimental investigations. A quantitative correlation is parametrized based on the numerical results. We find, that the flame initiation point shifts with increasing pressure from anchoring behind a downstream located bluff body towards anchoring upstream at the hydrogen jet. The numerical NOx emissions trend regarding to a variation of pressure is in good agreement with the experimental results. The pressure has an impact on both, the residence time within the maximum temperature region and on the peak temperature itself. In conclusion, the numerical model proved to be adequate for future prototype design exploration studies targeting on improving the operating range. KW - Gas turbine combustion KW - Hydrogen KW - NOx emissions KW - Flame temperature KW - Flame residence time Y1 - 2021 U6 - https://doi.org/10.1299/jsmeicope.2021.15.2021-0237 N1 - International Conference on Power Engineering 2021 (ICOPE-2021). October 17 - 21, 2021. Kobe, Japan (Online) ER - TY - CHAP A1 - Horikawa, Atsushi A1 - Okada, Kunio A1 - Yamaguchi, Masato A1 - Aoki, Shigeki A1 - Wirsum, Manfred A1 - Funke, Harald A1 - Kusterer, Karsten T1 - Combustor development and engine demonstration of micro-mix hydrogen combustion applied to M1A-17 gas turbine T2 - Conference Proceedings Turbo Expo: Power for Land, Sea and Air, Volume 3B: Combustion, Fuels, and Emissions N2 - Kawasaki Heavy Industries, LTD. (KHI) has research and development projects for a future hydrogen society. These projects comprise the complete hydrogen cycle, including the production of hydrogen gas, the refinement and liquefaction for transportation and storage, and finally the utilization in a gas turbine for electricity and heat supply. Within the development of the hydrogen gas turbine, the key technology is stable and low NOx hydrogen combustion, namely the Dry Low NOx (DLN) hydrogen combustion. KHI, Aachen University of Applied Science, and B&B-AGEMA have investigated the possibility of low NOx micro-mix hydrogen combustion and its application to an industrial gas turbine combustor. From 2014 to 2018, KHI developed a DLN hydrogen combustor for a 2MW class industrial gas turbine with the micro-mix technology. Thereby, the ignition performance, the flame stability for equivalent rotational speed, and higher load conditions were investigated. NOx emission values were kept about half of the Air Pollution Control Law in Japan: 84ppm (O2-15%). Hereby, the elementary combustor development was completed. From May 2020, KHI started the engine demonstration operation by using an M1A-17 gas turbine with a co-generation system located in the hydrogen-fueled power generation plant in Kobe City, Japan. During the first engine demonstration tests, adjustments of engine starting and load control with fuel staging were investigated. On 21st May, the electrical power output reached 1,635 kW, which corresponds to 100% load (ambient temperature 20 °C), and thereby NOx emissions of 65 ppm (O2-15, 60 RH%) were verified. Here, for the first time, a DLN hydrogen-fueled gas turbine successfully generated power and heat. KW - industrial gas turbine KW - combustor development KW - engine demonstration KW - fuels KW - hydrogen Y1 - 2021 U6 - https://doi.org/10.1115/GT2021-59666 N1 - ASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition. June 7–11, 2021. Virtual, Online. Paper No: GT2021-59666, V03BT04A014 ER - TY - CHAP A1 - Kroniger, Daniel A1 - Horikawa, Atsushi A1 - Funke, Harald A1 - Pfäffle, Franziska A1 - Kishimoto, Tsuyoshi A1 - Okada, Koichi T1 - Experimental and numerical investigation on the effect of pressure on micromix hydrogen combustion T2 - Conference Proceedings Turbo Expo: Power for Land, Sea and Air, Volume 3A: Combustion, Fuels, and Emissions N2 - The micromix (MMX) combustion concept is a DLN gas turbine combustion technology designed for high hydrogen content fuels. Multiple non-premixed miniaturized flames based on jet in cross-flow (JICF) are inherently safe against flashback and ensure a stable operation in various operative conditions. The objective of this paper is to investigate the influence of pressure on the micromix flame with focus on the flame initiation point and the NOx emissions. A numerical model based on a steady RANS approach and the Complex Chemistry model with relevant reactions of the GRI 3.0 mechanism is used to predict the reactive flow and NOx emissions at various pressure conditions. Regarding the turbulence-chemical interaction, the Laminar Flame Concept (LFC) and the Eddy Dissipation Concept (EDC) are compared. The numerical results are validated against experimental results that have been acquired at a high pressure test facility for industrial can-type gas turbine combustors with regard to flame initiation and NOx emissions. The numerical approach is adequate to predict the flame initiation point and NOx emission trends. Interestingly, the flame shifts its initiation point during the pressure increase in upstream direction, whereby the flame attachment shifts from anchoring behind a downstream located bluff body towards anchoring directly at the hydrogen jet. The LFC predicts this change and the NOx emissions more accurately than the EDC. The resulting NOx correlation regarding the pressure is similar to a non-premixed type combustion configuration. KW - NOx emissions KW - hydrogen KW - combustor KW - gas turbine Y1 - 2021 U6 - https://doi.org/10.1115/GT2021-58926 N1 - ASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition, June 7–11, 2021, Virtual, Online. Paper No: GT2021-58926, V03AT04A025 PB - ASME CY - New York, NY 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 - https://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 - 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 - https://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 - 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 - https://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 - Leise, Philipp A1 - Altherr, Lena A1 - Simon, Nicolai A1 - Pelz, Peter F. T1 - Finding global-optimal gearbox designs for battery electric vehicles T2 - Optimization of complex systems - theory, models, algorithms and applications : WCGO 2019 N2 - In order to maximize the possible travel distance of battery electric vehicles with one battery charge, it is mandatory to adjust all components of the powertrain carefully to each other. While current vehicle designs mostly simplify the powertrain rigorously and use an electric motor in combination with a gearbox with only one fixed transmission ratio, the use of multi-gear systems has great potential. First, a multi-speed system is able to improve the overall energy efficiency. Secondly, it is able to reduce the maximum momentum and therefore to reduce the maximum current provided by the traction battery, which results in a longer battery lifetime. In this paper, we present a systematic way to generate multi-gear gearbox designs that—combined with a certain electric motor—lead to the most efficient fulfillment of predefined load scenarios and are at the same time robust to uncertainties in the load. Therefore, we model the electric motor and the gearbox within a Mixed-Integer Nonlinear Program, and optimize the efficiency of the mechanical parts of the powertrain. By combining this mathematical optimization program with an unsupervised machine learning algorithm, we are able to derive global-optimal gearbox designs for practically relevant momentum and speed requirements. KW - Powertrain KW - Gearbox KW - Optimization KW - BEV KW - WLTP Y1 - 2019 SN - 978-3-030-21802-7 U6 - https://doi.org/10.1007/978-3-030-21803-4_91 SP - 916 EP - 925 PB - Springer CY - Cham ER - TY - CHAP A1 - Stenger, David A1 - Altherr, Lena A1 - Abel, Dirk T1 - Machine learning and metaheuristics for black-box optimization of product families: a case-study investigating solution quality vs. computational overhead T2 - Operations Research Proceedings 2018 N2 - In product development, numerous design decisions have to be made. Multi-domain virtual prototyping provides a variety of tools to assess technical feasibility of design options, however often requires substantial computational effort for just a single evaluation. A special challenge is therefore the optimal design of product families, which consist of a group of products derived from a common platform. Finding an optimal platform configuration (stating what is shared and what is individually designed for each product) and an optimal design of all products simultaneously leads to a mixed-integer nonlinear black-box optimization model. We present an optimization approach based on metamodels and a metaheuristic. To increase computational efficiency and solution quality, we compare different types of Gaussian process regression metamodels adapted from the domain of machine learning, and combine them with a genetic algorithm. We illustrate our approach on the example of a product family of electrical drives, and investigate the trade-off between solution quality and computational overhead. KW - Product family optimization KW - Mixed-integer nonlinear black-box optimization KW - Engineering optimization KW - Machine learning Y1 - 2019 SN - 978-3-030-18499-5 (Print) SN - 978-3-030-18500-8 (Online) U6 - https://doi.org/10.1007/978-3-030-18500-8_47 SP - 379 EP - 385 PB - Springer CY - Cham ER - TY - JOUR A1 - Olbertz, Klaus T1 - Arbeitsrechtliche Akzente der Gesetzgebung und Rechtsprechung in 2018 : Ein kurzweiliger Rückblick auf das Arbeitsrecht des vergangenen Jahres JF - NWB - Steuer- und Wirtschaftsrecht Y1 - 2019 SN - 0028-3460 IS - 5 SP - 266 EP - 279 ER - TY - JOUR A1 - Olbertz, Klaus T1 - Auslandsentsendungen im arbeitsrechtlichen Zusammenhang : Ausgestaltung eines Entsendungsvertrags und mitbestimmungsrechtliche Aspekte JF - NWB - Steuer- und Wirtschaftsrecht Y1 - 2019 SN - 0028-3460 IS - 19 SP - 1400 EP - 1406 ER - TY - JOUR A1 - Olbertz, Klaus T1 - Rechtssichere Vereinbarungen von Kündigungsfristen im Arbeitsvertrag : Weitestgehende Abdingbarkeit gesetzlicher Vorgaben ermöglicht passgenaue Gestaltungen JF - NWB - Steuer- und Wirtschaftsrecht Y1 - 2019 SN - 0028-3460 IS - 23 SP - 1693 EP - 1699 ER - TY - JOUR A1 - Olbertz, Klaus T1 - Die Optionen des Arbeitgebers nach Krankmeldung des Arbeitnehmers : Ein Überblick über die Rechte und Pflichten des Arbeitgebers bei Arbeitsunfähigkeit des Mitarbeiters JF - NWB - Steuer- und Wirtschaftsrecht Y1 - 2019 SN - 0028-3460 IS - 30 SP - 2222 EP - 2229 ER - TY - JOUR A1 - Olbertz, Klaus T1 - Die arbeitsvertragliche Vereinbarung von Vertragsstrafen : Anforderungen an wirksame Vertragsstrafenabreden in Formulararbeitsverträgen beachten JF - NWB - Steuer- und Wirtschaftsrecht Y1 - 2019 SN - 0028-3460 IS - 45 SP - 3302 EP - 3308 ER - TY - JOUR A1 - Olbertz, Klaus T1 - Jahresrückblick Arbeitsrecht 2019 : Gesetzesänderungen und insbesondere im Zeichen des Befristungs- und Urlaubsrechts stehende höchstrichterliche Rechtsprechung JF - NWB - Steuer- und Wirtschaftsrecht N2 - In Fortschreibung des Jahresrückblicks 2018 (Olbertz, NWB 5/2019 S. 266 ) skizziert der vorliegende Beitrag die jüngsten nennenswerten Entwicklungen im Arbeitsrecht des Jahres 2019. Im Bereich der Gesetzgebung, mit dem sich der erste Teil des Beitrags befasst, betrifft dies etwa das Fachkräfteeinwanderungsgesetz, die angestoßenen Schutzvorschriften für Whistleblower oder das gesetzlich verankerte Recht auf Brückenteilzeit. In der arbeitsrechtlichen höchstrichterlichen Rechtsprechung stand das Jahr 2019 insbesondere im Zeichen des Befristungs- und des Urlaubsrechts. Was hier und darüber hinaus wegweisend war, zeigt der zweite Teil des Beitrags. Y1 - 2020 SN - 0028-3460 IS - 8 SP - 557 EP - 569 PB - NWB-Verl. CY - Herne ER - TY - JOUR A1 - Olbertz, Klaus T1 - GmbH-Geschäftsführer: das eine Mal Arbeitnehmer, das andere Mal nicht : Arbeits- und sozialrechtliche Anwendung von Schutzvorschriften auf den Geschäftsführer von A bis Z JF - NWB - Steuer- und Wirtschaftsrecht Y1 - 2020 SN - 0028-3460 IS - 19 SP - 1431 EP - 1441 PB - NWB-Verl. CY - Herne ER - TY - JOUR A1 - Olbertz, Klaus T1 - Wenn der „leitende“ Angestellte doch nur ein „normaler“ Arbeitnehmer ist ... : Zur Rechtsstellung leitender Angestellter, zu Fehleinschätzungen des Arbeitgebers und Praxishinweisen JF - NWB - Steuer- und Wirtschaftsrecht Y1 - 2020 SN - 0028-3460 IS - 32 SP - 2397 EP - 2406 PB - NWB-Verl. CY - Herne ER - TY - JOUR A1 - Olbertz, Klaus T1 - Die Dienstreisezeit als Arbeitszeit – oder doch nicht? : Zur arbeitgeberfreundlichen Bewertung von Dienstreisezeiten durch das Bundesarbeitsgericht JF - NWB - Steuer- und Wirtschaftsrecht N2 - Der arbeitsrechtlich richtige Umgang mit Zeiten einer Dienstreise kann in der betrieblichen Praxis Probleme bereiten. Ob die Reisezeiten als solche Arbeitszeit i. S. des Arbeitszeitgesetzes (ArbZG ) darstellen, also bspw. auf die tägliche Höchstarbeitszeit angerechnet werden müssen oder nicht, ist oftmals genauso unklar wie die Frage, ob und inwieweit Reisezeiten vergütungspflichtig sind. Aber auch, ob ein Arbeitnehmer überhaupt zur Durchführung einer Dienstreise verpflichtet werden kann, ist ein möglicher Anlass von Streitigkeiten zwischen den Arbeitsvertragsparteien, wie verschiedene Gerichtsentscheidungen zeigen. Der nachfolgende Beitrag beantwortet die aufgeworfenen Fragen und gibt hierzu einen praxisorientierten Überblick. Y1 - 2021 SN - 0028-3460 IS - 1 SP - 38 EP - 44 ER - TY - CHAP A1 - Mandekar, Swati A1 - Jentsch, Lina A1 - Lutz, Kai A1 - Behbahani, Mehdi A1 - Melnykowycz, Mark T1 - Earable design analysis for sleep EEG measurements T2 - UbiComp '21 N2 - Conventional EEG devices cannot be used in everyday life and hence, past decade research has been focused on Ear-EEG for mobile, at-home monitoring for various applications ranging from emotion detection to sleep monitoring. As the area available for electrode contact in the ear is limited, the electrode size and location play a vital role for an Ear-EEG system. In this investigation, we present a quantitative study of ear-electrodes with two electrode sizes at different locations in a wet and dry configuration. Electrode impedance scales inversely with size and ranges from 450 kΩ to 1.29 MΩ for dry and from 22 kΩ to 42 kΩ for wet contact at 10 Hz. For any size, the location in the ear canal with the lowest impedance is ELE (Left Ear Superior), presumably due to increased contact pressure caused by the outer-ear anatomy. The results can be used to optimize signal pickup and SNR for specific applications. We demonstrate this by recording sleep spindles during sleep onset with high quality (5.27 μVrms). KW - EEG KW - sensors KW - Impedance Spectroscopy KW - Sleep EEG KW - biopotential electrodes Y1 - 2021 U6 - https://doi.org/10.1145/3460418.3479328 N1 - UbiComp '21: Adjunct Proceedings of the 2021 ACM International Joint Conference on Pervasive and Ubiquitous Computing and Proceedings of the 2021 ACM International Symposium on Wearable Computers, September 21–26, 2021, Virtual, USA SP - 171 EP - 175 ER - TY - JOUR A1 - Heinke, Lars N. A1 - Knicker, Axel J. A1 - Albracht, Kirsten T1 - Test-retest reliability of the internal shoulder rotator muscles' stretch reflex in healthy men JF - Journal of Electromyography and Kinesiology N2 - Until now the reproducibility of the short latency stretch reflex of the internal rotator muscles of the glenohumeral joint has not been identified. Twenty-three healthy male participants performed three sets of external shoulder rotation stretches with various pre-activation levels on two different dates of measurement to assess test-retest reliability. All stretches were applied with a dynamometer acceleration of 104°/s2 and a velocity of 150°/s. Electromyographical response was measured via surface EMG. Reflex latencies showed a pre-activation effect (ƞ2 = 0,355). ICC ranged from 0,735 to 0,909 indicating an overall “good” relative reliability. SRD 95% lay between ±7,0 to ±12,3 ms.. The reflex gain showed overall poor test-retest reproducibility. The chosen methodological approach presented a suitable test protocol for shoulder muscles stretch reflex latency evaluation. A proof-of-concept study to validate the presented methodical approach in shoulder involvement including subjects with clinically relevant conditions is recommended. KW - stretch reflex KW - shoulder KW - test-retest reliability KW - intraclass correlation coefficient KW - standard error of measurement Y1 - 2021 U6 - https://doi.org/10.1016/j.jelekin.2021.102611 SN - 1050-6411 VL - 62 IS - Article 102611 PB - Elsevier CY - Amsterdam ER - TY - BOOK A1 - Dikta, Gerhard A1 - Scheer, Marsel T1 - Bootstrap Methods: With Applications in R N2 - This book provides a compact introduction to the bootstrap method. In addition to classical results on point estimation and test theory, multivariate linear regression models and generalized linear models are covered in detail. Special attention is given to the use of bootstrap procedures to perform goodness-of-fit tests to validate model or distributional assumptions. In some cases, new methods are presented here for the first time. The text is motivated by practical examples and the implementations of the corresponding algorithms are always given directly in R in a comprehensible form. Overall, R is given great importance throughout. Each chapter includes a section of exercises and, for the more mathematically inclined readers, concludes with rigorous proofs. The intended audience is graduate students who already have a prior knowledge of probability theory and mathematical statistics. Y1 - 2021 SN - 978-3-030-73480-0 U6 - https://doi.org/10.1007/978-3-030-73480-0 PB - Springer CY - Cham ER - TY - JOUR A1 - Heel, Mareike van A1 - Dikta, Gerhard A1 - Braekers, Roel T1 - Bootstrap based goodness‑of‑fit tests for binary multivariate regression models JF - Journal of the Korean Statistical Society N2 - We consider a binary multivariate regression model where the conditional expectation of a binary variable given a higher-dimensional input variable belongs to a parametric family. Based on this, we introduce a model-based bootstrap (MBB) for higher-dimensional input variables. This test can be used to check whether a sequence of independent and identically distributed observations belongs to such a parametric family. The approach is based on the empirical residual process introduced by Stute (Ann Statist 25:613–641, 1997). In contrast to Stute and Zhu’s approach (2002) Stute & Zhu (Scandinavian J Statist 29:535–545, 2002), a transformation is not required. Thus, any problems associated with non-parametric regression estimation are avoided. As a result, the MBB method is much easier for users to implement. To illustrate the power of the MBB based tests, a small simulation study is performed. Compared to the approach of Stute & Zhu (Scandinavian J Statist 29:535–545, 2002), the simulations indicate a slightly improved power of the MBB based method. Finally, both methods are applied to a real data set. Y1 - 2021 U6 - https://doi.org/10.1007/s42952-021-00142-4 SN - 2005-2863 (Online) SN - 1226-3192 (Print) N1 - Corresponding author: Mareike van Heel VL - 51 PB - Springer Nature CY - Singapur ER - TY - CHAP A1 - Hüning, Felix A1 - Wache, Franz-Josef A1 - Magiera, David T1 - Redundant bus systems using dual-mode radio T2 - Proceedings of Sixth International Congress on Information and Communication Technology N2 - Communication via serial bus systems, like CAN, plays an important role for all kinds of embedded electronic and mechatronic systems. To cope up with the requirements for functional safety of safety-critical applications, there is a need to enhance the safety features of the communication systems. One measure to achieve a more robust communication is to add redundant data transmission path to the applications. In general, the communication of real-time embedded systems like automotive applications is tethered, and the redundant data transmission lines are also tethered, increasing the size of the wiring harness and the weight of the system. A radio link is preferred as a redundant transmission line as it uses a complementary transmission medium compared to the wired solution and in addition reduces wiring harness size and weight. Standard wireless links like Wi-Fi or Bluetooth cannot meet the requirements for real-time capability with regard to bus communication. Using the new dual-mode radio enables a redundant transmission line meeting all requirements with regard to real-time capability, robustness and transparency for the data bus. In addition, it provides a complementary transmission medium with regard to commonly used tethered links. A CAN bus system is used to demonstrate the redundant data transfer via tethered and wireless CAN. Y1 - 2021 SN - 978-981-16-2379-0 SN - 978-981-16-2380-6 U6 - https://doi.org/10.1007/978-981-16-2380-6_73 N1 - Sixth International Congress on Information and Communication Technology, ICICT 2021, Brunel University, London, February 25–26, 2021 SP - 835 EP - 842 PB - Springer CY - Singapore ER - TY - BOOK A1 - Gell, Sebastian T1 - Determinants of earnings forecast error, earnings forecast revision and earnings forecast accuracy N2 - ​Earnings forecasts are ubiquitous in today’s financial markets. They are essential indicators of future firm performance and a starting point for firm valuation. Extremely inaccurate and overoptimistic forecasts during the most recent financial crisis have raised serious doubts regarding the reliability of such forecasts. This thesis therefore investigates new determinants of forecast errors and accuracy. In addition, new determinants of forecast revisions are examined. More specifically, the thesis answers the following questions: 1) How do analyst incentives lead to forecast errors? 2) How do changes in analyst incentives lead to forecast revisions?, and 3) What factors drive differences in forecast accuracy? Y1 - 2012 SN - 978-3-8349-3936-4 SN - 978-3-8349-3937-1 U6 - https://doi.org/10.1007/978-3-8349-3937-1 N1 - Titel in der Buchreihe: Quantitatives Controlling PB - Springer Gabler CY - Wiesbaden ER - TY - JOUR A1 - Klettke, Tanja A1 - Homburg, Carsten A1 - Gell, Sebastian T1 - How to measure analyst forecast effort JF - European Accounting Review N2 - We introduce a new way to measure the forecast effort that analysts devote to their earnings forecasts by measuring the analyst's general effort for all covered firms. While the commonly applied effort measure is based on analyst behaviour for one firm, our measure considers analyst behaviour for all covered firms. Our general effort measure captures additional information about analyst effort and thus can identify accurate forecasts. We emphasise the importance of investigating analyst behaviour in a larger context and argue that analysts who generally devote substantial forecast effort are also likely to devote substantial effort to a specific firm, even if this effort might not be captured by a firm-specific measure. Empirical results reveal that analysts who devote higher general forecast effort issue more accurate forecasts. Additional investigations show that analysts' career prospects improve with higher general forecast effort. Our measure improves on existing methods as it has higher explanatory power regarding differences in forecast accuracy than the commonly applied effort measure. Additionally, it can address research questions that cannot be examined with a firm-specific measure. It provides a simple but comprehensive way to identify accurate analysts. Y1 - 2015 U6 - https://doi.org/10.1080/09638180.2014.909291 SN - 0963-8180 VL - 24 IS - 1 SP - 129 EP - 146 PB - Taylor & Francis CY - London ER - TY - CHAP A1 - Klöser, Lars A1 - Kohl, Philipp A1 - Kraft, Bodo A1 - Zündorf, Albert T1 - Multi-attribute relation extraction (MARE): simplifying the application of relation extraction T2 - Proceedings of the 2nd International Conference on Deep Learning Theory and Applications DeLTA - Volume 1 N2 - Natural language understanding’s relation extraction makes innovative and encouraging novel business concepts possible and facilitates new digitilized decision-making processes. Current approaches allow the extraction of relations with a fixed number of entities as attributes. Extracting relations with an arbitrary amount of attributes requires complex systems and costly relation-trigger annotations to assist these systems. We introduce multi-attribute relation extraction (MARE) as an assumption-less problem formulation with two approaches, facilitating an explicit mapping from business use cases to the data annotations. Avoiding elaborated annotation constraints simplifies the application of relation extraction approaches. The evaluation compares our models to current state-of-the-art event extraction and binary relation extraction methods. Our approaches show improvement compared to these on the extraction of general multi-attribute relations. Y1 - 2021 SN - 978-989-758-526-5 U6 - https://doi.org/10.5220/0010559201480156 N1 - 2nd International Conference on Deep Learning Theory and Applications, DeLTA2021, July 7-9, 2021 SP - 148 EP - 156 PB - SciTePress CY - Setúbal ER - TY - CHAP A1 - Adenacker, J. A1 - Gerhards, Benjamin A1 - Otten, Christian A1 - Schleser, Markus T1 - Laserstrahlschweißen von Aluminium-Kupfer-Werkstoffkombinationen für die Elektromobilität T2 - DVS CONGRESS 2021 Y1 - 2021 SN - 978-3-96144-146-4 N1 - DVS CONGRESS 2021, 14. – 17. September 2021, Essen. Große Schweißtechnische Tagung 2021, DVS CAMPUS 2021. DVS Berichte, Band: 371 SP - 31 EP - 38 PB - DVS Media GmbH CY - Düsseldorf ER - TY - JOUR A1 - Timme, Michael T1 - Rechtsprechungsübersicht zum Wohnraummietrecht JF - Monatsschrift für Deutsches Recht Y1 - 2021 U6 - https://doi.org/10.9785/mdtr-2021-750113 SN - 2194-4202 VL - 75 IS - 1 SP - 6 EP - 11 PB - Verlag Dr. Otto Schmidt CY - Köln ER - TY - BOOK A1 - Timme, Michael T1 - BGB Crashkurs: der sichere Weg durch die Prüfung N2 - Dieser "Crashkurs" eignet sich ausgezeichnet für die kompakte Wiederholung und die zielgerichtete Prüfungsvorbereitung. Das Buch ist aufgrund seiner fallbezogenen Ausrichtung vor allem für Anfänger gedacht, eignet sich aber auch für fortgeschrittene Studierende zur kompakten Wiederholung. Einfache Merksätze, Fälle, Übersichten, Definitionen und kurze Zusammenfassungen lassen sich leicht einprägen und geben Sicherheit für die Prüfung. Vorteile auf einen Blick: Das wichtigste BGB-Know-how als Repetitorium vor der Prüfung, mit erprobten Merksätzen und kurzen Zusammenfassungen, Fall für Fall sicher durch die Prüfung Y1 - 2021 SN - 978-3-406-77349-5 PB - C.H. Beck CY - München ET - 6. Auflage ER - TY - BOOK A1 - Timme, Michael T1 - WEG - Wohnungeigentumsgesetz / Hrsg. von Michael Timme . Stand 01.02.2020 ; Edition: 40 Y1 - 2020 N1 - Beck´scher Online-Kommentar WEG (Hrsg.: Timme) PB - Beck CY - München ER - TY - BOOK A1 - Timme, Michael T1 - WEG - Wohnungeigentumsgesetz / Hrsg. von Michael Timme . Stand: 01.05.2020 ; Edition 41 Y1 - 2020 N1 - Beck´scher Online-Kommentar WEG (Hrsg.: Timme) PB - Beck CY - München ER - TY - CHAP A1 - Kohl, Philipp A1 - Schmidts, Oliver A1 - Klöser, Lars A1 - Werth, Henri A1 - Kraft, Bodo A1 - Zündorf, Albert T1 - STAMP 4 NLP – an agile framework for rapid quality-driven NLP applications development T2 - Quality of Information and Communications Technology. QUATIC 2021 N2 - The progress in natural language processing (NLP) research over the last years, offers novel business opportunities for companies, as automated user interaction or improved data analysis. Building sophisticated NLP applications requires dealing with modern machine learning (ML) technologies, which impedes enterprises from establishing successful NLP projects. Our experience in applied NLP research projects shows that the continuous integration of research prototypes in production-like environments with quality assurance builds trust in the software and shows convenience and usefulness regarding the business goal. We introduce STAMP 4 NLP as an iterative and incremental process model for developing NLP applications. With STAMP 4 NLP, we merge software engineering principles with best practices from data science. Instantiating our process model allows efficiently creating prototypes by utilizing templates, conventions, and implementations, enabling developers and data scientists to focus on the business goals. Due to our iterative-incremental approach, businesses can deploy an enhanced version of the prototype to their software environment after every iteration, maximizing potential business value and trust early and avoiding the cost of successful yet never deployed experiments. KW - Machine learning KW - Process model KW - Natural language processing Y1 - 2021 SN - 978-3-030-85346-4 SN - 978-3-030-85347-1 U6 - https://doi.org/10.1007/978-3-030-85347-1_12 N1 - International Conference on the Quality of Information and Communications Technology, QUATIC 2021, 8-11 September, Algarve, Portugal SP - 156 EP - 166 PB - Springer CY - Cham ER - TY - CHAP A1 - Schmidts, Oliver A1 - Kraft, Bodo A1 - Winkens, Marvin A1 - Zündorf, Albert T1 - Catalog integration of heterogeneous and volatile product data T2 - DATA 2020: Data Management Technologies and Applications N2 - The integration of frequently changing, volatile product data from different manufacturers into a single catalog is a significant challenge for small and medium-sized e-commerce companies. They rely on timely integrating product data to present them aggregated in an online shop without knowing format specifications, concept understanding of manufacturers, and data quality. Furthermore, format, concepts, and data quality may change at any time. Consequently, integrating product catalogs into a single standardized catalog is often a laborious manual task. Current strategies to streamline or automate catalog integration use techniques based on machine learning, word vectorization, or semantic similarity. However, most approaches struggle with low-quality or real-world data. We propose Attribute Label Ranking (ALR) as a recommendation engine to simplify the integration process of previously unknown, proprietary tabular format into a standardized catalog for practitioners. We evaluate ALR by focusing on the impact of different neural network architectures, language features, and semantic similarity. Additionally, we consider metrics for industrial application and present the impact of ALR in production and its limitations. Y1 - 2021 SN - 978-3-030-83013-7 U6 - https://doi.org/10.1007/978-3-030-83014-4_7 N1 - International Conference on Data Management Technologies and Applications, DATA 2020, 7-9 July SP - 134 EP - 153 PB - Springer CY - Cham 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 - https://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 - JOUR A1 - Müller, Tim M. A1 - Leise, Philipp A1 - Lorenz, Imke-Sophie A1 - Altherr, Lena A1 - Pelz, Peter F. T1 - Optimization and validation of pumping system design and operation for water supply in high-rise buildings JF - Optimization and Engineering N2 - The application of mathematical optimization methods for water supply system design and operation provides the capacity to increase the energy efficiency and to lower the investment costs considerably. We present a system approach for the optimal design and operation of pumping systems in real-world high-rise buildings that is based on the usage of mixed-integer nonlinear and mixed-integer linear modeling approaches. In addition, we consider different booster station topologies, i.e. parallel and series-parallel central booster stations as well as decentral booster stations. To confirm the validity of the underlying optimization models with real-world system behavior, we additionally present validation results based on experiments conducted on a modularly constructed pumping test rig. Within the models we consider layout and control decisions for different load scenarios, leading to a Deterministic Equivalent of a two-stage stochastic optimization program. We use a piecewise linearization as well as a piecewise relaxation of the pumps’ characteristics to derive mixed-integer linear models. Besides the solution with off-the-shelf solvers, we present a problem specific exact solving algorithm to improve the computation time. Focusing on the efficient exploration of the solution space, we divide the problem into smaller subproblems, which partly can be cut off in the solution process. Furthermore, we discuss the performance and applicability of the solution approaches for real buildings and analyze the technical aspects of the solutions from an engineer’s point of view, keeping in mind the economically important trade-off between investment and operation costs. KW - Technical Operations Research KW - MINLP KW - MILP KW - Experimental validation KW - Pumping systems Y1 - 2020 U6 - https://doi.org/10.1007/s11081-020-09553-4 SN - 1573-2924 VL - 2021 IS - 22 SP - 643 EP - 686 PB - Springer 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 - https://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 - JOUR A1 - Altherr, Lena A1 - Leise, Philipp A1 - Pfetsch, Marc E. A1 - Schmitt, Andreas T1 - Algorithmic design and resilience assessment of energy efficient high-rise water supply systems JF - Applied Mechanics and Materials N2 - High-rise water supply systems provide water flow and suitable pressure in all levels of tall buildings. To design such state-of-the-art systems, the consideration of energy efficiency and the anticipation of component failures are mandatory. In this paper, we use Mixed-Integer Nonlinear Programming to compute an optimal placement of pipes and pumps, as well as an optimal control strategy.Moreover, we consider the resilience of the system to pump failures. A resilient system is able to fulfill a predefined minimum functionality even though components fail or are restricted in their normal usage. We present models to measure and optimize the resilience. To demonstrate our approach, we design and analyze an optimal resilient decentralized water supply system inspired by a real-life hotel building. KW - MINLP KW - Buffering Capacity KW - Uncertainty KW - Water Supply Networks KW - Booster Stations Y1 - 2018 U6 - https://doi.org/10.4028/www.scientific.net/AMM.885.211 SN - 1662-7482 VL - 885 SP - 211 EP - 223 PB - Trans Tech Publications CY - Bäch ER - TY - JOUR A1 - Zabirov, Alexander A1 - Schleser, Markus A1 - Bucherer, Sebastian T1 - Füge- und Dichtkonzept für einen Leichtbauverbrennungsmotor JF - adhäsion KLEBEN & DICHTEN Y1 - 2021 U6 - https://doi.org/10.1007/s35145-021-0531-5 SN - 2192-8681 VL - 65 IS - 11 SP - 12 EP - 19 PB - Springer Nature CY - Cham ER - TY - CHAP A1 - Pfetsch, Marc E. A1 - Abele, Eberhard A1 - Altherr, Lena A1 - Bölling, Christian A1 - Brötz, Nicolas A1 - Dietrich, Ingo A1 - Gally, Tristan A1 - Geßner, Felix A1 - Groche, Peter A1 - Hoppe, Florian A1 - Kirchner, Eckhard A1 - Kloberdanz, Hermann A1 - Knoll, Maximilian A1 - Kolvenbach, Philip A1 - Kuttich-Meinlschmidt, Anja A1 - Leise, Philipp A1 - Lorenz, Ulf A1 - Matei, Alexander A1 - Molitor, Dirk A. A1 - Niessen, Pia A1 - Pelz, Peter F. A1 - Rexer, Manuel A1 - Schmitt, Andreas A1 - Schmitt, Johann M. A1 - Schulte, Fiona A1 - Ulbrich, Stefan A1 - Weigold, Matthias T1 - Strategies for mastering uncertainty T2 - Mastering uncertainty in mechanical engineering N2 - This chapter describes three general strategies to master uncertainty in technical systems: robustness, flexibility and resilience. It builds on the previous chapters about methods to analyse and identify uncertainty and may rely on the availability of technologies for particular systems, such as active components. Robustness aims for the design of technical systems that are insensitive to anticipated uncertainties. Flexibility increases the ability of a system to work under different situations. Resilience extends this characteristic by requiring a given minimal functional performance, even after disturbances or failure of system components, and it may incorporate recovery. The three strategies are described and discussed in turn. Moreover, they are demonstrated on specific technical systems. Y1 - 2021 SN - 978-3-030-78353-2 U6 - https://doi.org/10.1007/978-3-030-78354-9_6 N1 - Part of the Springer Tracts in Mechanical Engineering book series (STME) SP - 365 EP - 456 PB - Springer CY - Cham ER - TY - JOUR A1 - Olbertz, Klaus T1 - Wichtige arbeitsrechtliche Entwicklungen im Jahr 2020 : Der Jahresrückblick auf alles Wissenswerte im Arbeitsrecht des vergangenen Jahres JF - NWB - Steuer- und Wirtschaftsrecht N2 - Im Anschluss an die arbeitsrechtlichen Jahresübersichten der vergangenen Jahre (NWB 5/2019 S. 266; NWB 8/2020 S. 557) gibt der nachfolgende Beitrag einen Überblick über relevante Entwicklungen im Arbeitsrecht des Jahres 2020. Der erste Teil beschäftigt sich hierbei mit gesetzlichen Änderungen. Neben Regelungen, die auf die COVID-19-Pandemie zurückgeführt werden können, hat der Gesetzgeber auch andere Vorhaben umgesetzt. So wurde u. a. das Arbeitnehmerentsenderecht reformiert. Für Diskussionen sorgt(e) zudem das Gesetzesvorhaben zur Regelung mobiler Arbeit. Im zweiten Teil werden für die Praxis wichtige höchstrichterliche Gerichtsentscheidungen zum Arbeitsrecht erläutert, alphabetisch sortiert von A (wie Antidiskriminierungsrecht) bis U (wie Urlaub). Y1 - 2021 SN - 0028-3460 IS - 10 SP - 703 EP - 715 ER - TY - JOUR A1 - Olbertz, Klaus T1 - Die Flexibilisierung von Arbeitszeit durch den Abruf von Arbeit : Möglichkeiten und Grenzen arbeitsvertraglicher Gestaltung zur Vermeidung von „Leerlaufzeiten“ JF - NWB - Steuer- und Wirtschaftsrecht N2 - Die Arbeitswelt ist im Umbruch. Der Bedarf an flexiblen Arbeitszeitmodellen nimmt stetig zu, wobei die Corona-Pandemie dieses Bedürfnis nochmals verschärft hat. Gerade auch in kleineren und mittleren Unternehmen wächst die Notwendigkeit, den Einsatz der Beschäftigten möglichst bedarfsgerecht zu steuern, also bei guter Auftragslage mehr Arbeitszeit abzurufen und bei ausbleibenden Aufträgen die Arbeitszeit zu reduzieren und somit bezahlte „Leerlaufzeiten“ zu vermeiden. Der Gesetzgeber stellt den Arbeitgebern hierfür das Instrument der sog. Abrufarbeit ( § 12 Teilzeit- und Befristungsgesetz – TzBfG ) zur Verfügung. In dem nachfolgenden Beitrag werden Möglichkeiten und Grenzen der Abrufarbeit skizziert und konkrete arbeitsvertragliche Gestaltungsmöglichkeiten aufgezeigt. Y1 - 2021 SN - 0028-3460 IS - 15 SP - 1055 EP - 1063 ER - TY - JOUR A1 - Olbertz, Klaus T1 - Vertragsgestaltungen bei der Beschäftigung von Rentnern in Unternehmen : (Befristete) Beschäftigungsverhältnisse als sinnvolles Instrument zum Schließen von Personallücken JF - NWB - Steuer- und Wirtschaftsrecht Y1 - 2021 SN - 0028-3460 IS - 25 SP - 1810 EP - 1817 ER - TY - GEN A1 - Olbertz, Klaus T1 - Sozialversicherungspflicht eines Minderheitsgesellschafter-Geschäftsführers einer Familiengesellschaft T2 - Gesellschafts- und Wirtschaftsrecht : GWR Y1 - 2019 SN - 1868-1816 N1 - Anmerkung zum Beschluss des LSG Niedersachsen-Bremen v. 20.12.2018 – L 12 BA 23/18 B ER IS - 3 SP - 48 EP - 48 ER -