TY - JOUR A1 - Frotscher, Ralf A1 - Muanghong, Danita A1 - Dursun, Gözde A1 - Goßmann, Matthias A1 - Temiz Artmann, Aysegül A1 - Staat, Manfred T1 - Sample-specific adaption of an improved electro-mechanical model of in vitro cardiac tissue JF - Journal of Biomechanics N2 - We present an electromechanically coupled computational model for the investigation of a thin cardiac tissue construct consisting of human-induced pluripotent stem cell-derived atrial, ventricular and sinoatrial cardiomyocytes. The mechanical and electrophysiological parts of the finite element model, as well as their coupling are explained in detail. The model is implemented in the open source finite element code Code_Aster and is employed for the simulation of a thin circular membrane deflected by a monolayer of autonomously beating, circular, thin cardiac tissue. Two cardio-active drugs, S-Bay K8644 and veratridine, are applied in experiments and simulations and are investigated with respect to their chronotropic effects on the tissue. These results demonstrate the potential of coupled micro- and macroscopic electromechanical models of cardiac tissue to be adapted to experimental results at the cellular level. Further model improvements are discussed taking into account experimentally measurable quantities that can easily be extracted from the obtained experimental results. The goal is to estimate the potential to adapt the presented model to sample specific cell cultures. KW - hiPS cardiomyocytes KW - Homogenization KW - Hodgkin–Huxley models KW - Frequency adaption KW - Electromechanical modeling KW - Drug simulation KW - Computational biomechanics KW - Cardiac tissue Y1 - 2016 U6 - https://doi.org/10.1016/j.jbiomech.2016.01.039 SN - 0021-9290 (Print) SN - 1873-2380 (Online) VL - 49 IS - 12 SP - 2428 EP - 2435 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Fiedler, Thomas M. A1 - Ladd, Mark E. A1 - Clemens, Markus A1 - Bitz, Andreas T1 - Safety of subjects during radiofrequency exposure in ultra-high-field magnetic resonance imaging JF - IEEE Letters on Electromagnetic Compatibility Practice and Applications N2 - Magnetic resonance imaging (MRI) is one of the most important medical imaging techniques. Since the introduction of MRI in the mid-1980s, there has been a continuous trend toward higher static magnetic fields to obtain i.a. a higher signal-to-noise ratio. The step toward ultra-high-field (UHF) MRI at 7 Tesla and higher, however, creates several challenges regarding the homogeneity of the spin excitation RF transmit field and the RF exposure of the subject. In UHF MRI systems, the wavelength of the RF field is in the range of the diameter of the human body, which can result in inhomogeneous spin excitation and local SAR hotspots. To optimize the homogeneity in a region of interest, UHF MRI systems use parallel transmit systems with multiple transmit antennas and time-dependent modulation of the RF signal in the individual transmit channels. Furthermore, SAR increases with increasing field strength, while the SAR limits remain unchanged. Two different approaches to generate the RF transmit field in UHF systems using antenna arrays close and remote to the body are investigated in this letter. Achievable imaging performance is evaluated compared to typical clinical RF transmit systems at lower field strength. The evaluation has been performed under consideration of RF exposure based on local SAR and tissue temperature. Furthermore, results for thermal dose as an alternative RF exposure metric are presented. Y1 - 2020 SN - 2637-6423 U6 - https://doi.org/10.1109/LEMCPA.2020.3029747 VL - 2 IS - 3 SP - 1 EP - 8 PB - IEEE CY - New York, NY ER - TY - JOUR A1 - Hartung, Frank A1 - Baldo, N. A1 - Horn, U. A1 - Kampmann, M. T1 - RTCP feedback based transmission rate control for 3G wireless multimedia streaming / Baldo, N. ; Horn, U. ; Kampmann, M. ; Hartung, F. ; JF - 15th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications, 2004. PIMRC 2004. Date:5-8 Sept. 2004 ; Vol. 3 Y1 - 2004 N1 - http://dx.doi.org/10.1109/PIMRC.2004.1368313 SP - 1817 EP - 1821 ER - TY - JOUR A1 - Wegner, Lena A1 - von Arx, Georg A1 - Sass-Klaassen, Ute G. W. A1 - Eilmann, Britta T1 - ROXAS – an efficient and accurate tool to detect vessels in diffuse-porous species JF - IAWA Journal / International Association of Wood Anatomists Y1 - 2013 U6 - https://doi.org/10.1163/22941932-00000034 SN - 0928-1541 (Print) SN - 2294-1932 (Online) VL - 34 IS - 4 SP - 425 EP - 432 PB - Brill CY - Leiden ER - TY - JOUR A1 - Gaigall, Daniel T1 - Rothman–Woodroofe symmetry test statistic revisited JF - Computational Statistics & Data Analysis N2 - The Rothman–Woodroofe symmetry test statistic is revisited on the basis of independent but not necessarily identically distributed random variables. The distribution-freeness if the underlying distributions are all symmetric and continuous is obtained. The results are applied for testing symmetry in a meta-analysis random effects model. The consistency of the procedure is discussed in this situation as well. A comparison with an alternative proposal from the literature is conducted via simulations. Real data are analyzed to demonstrate how the new approach works in practice. Y1 - 2020 U6 - https://doi.org/10.1016/j.csda.2019.106837 SN - 0167-9473 VL - 2020 IS - 142 SP - Artikel 106837 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Müller-Veggian, Mattea A1 - Lieder, R. M. A1 - Neskakis, A T1 - Rotational bands in ¹⁹⁵,¹⁹⁷ Tl JF - Nuclear physics / A. 299 (1978), H. 2 Y1 - 1978 SN - 0375-9474 SP - 255 EP - 284 ER - TY - JOUR A1 - Wittmann, Klaus A1 - Ulamec, S. A1 - Feuerbacher, B. A1 - Rosenbauer, H. (u.a.) T1 - Rosetta Lander - In Situ Investigation of a Cometary Nucleus JF - Lunar and Planetary Science. 28 (1997) Y1 - 1997 SN - 0270-9511 N1 - Proceedings of the 28th Annual Lunar and Planetary Science Conference, March 17-21, 1997, Houston, Texas SP - 1461 EP - 1462 ER - TY - JOUR A1 - Wittmann, Klaus A1 - Feuerbacher, B. A1 - Ulamec, S. A1 - Rosenbauer, H. (u.a.) T1 - Rosetta Lander - In Situ Characterisation of a Comet Nucleus JF - Acta Astronautica. 45 (1999), H. 4-9 Y1 - 1999 SN - 0094-5765 SP - 389 EP - 395 ER - TY - JOUR A1 - Hüning, Felix A1 - Hillgärtner, Michael A1 - Reke, Michael T1 - Rolling Labs – Teaching Vehicle Electronics from the Beginning JF - International Journal of Engineering Pedagogy (iJEP) Y1 - 2019 U6 - https://doi.org/10.3991/ijep.v9i1.9241 SN - 2192-4880 VL - 9 IS - 1 SP - 34 EP - 49 ER - TY - JOUR A1 - Wedrowski, M. A1 - Bruyndonckx, P. A1 - Tavernier, S. A1 - Zhi, L. A1 - Dang, J. A1 - Mendes, P. R. A1 - Perez, J. M. A1 - Ziemons, Karl T1 - Robustness of neural networks algorithm for gamma detection in monolithic block detector, positron emission tomography JF - 2009 IEEE Nuclear Science Symposium Conference Record (NSS/MIC) N2 - The monolithic scintillator block approach for gamma detection in the Positron Emission Tomography (PET) avoids estimating Depth of Interaction (DOI), reduces dead zones in detector and diminishes costs of detector production. Neural Networks (NN) are very efficient to determine the entrance point of a gamma incident on a scintillator block. This paper presents results on the robustness of the spatial resolution as a function of the random fraction in the data, temperature and HV fluctuations. This is important when implementing the method in a real scanner. Measurements were done with two Hamamatsu S8550 APD arrays, glued on a 20 × 20 × 10 mm3 monolithic LSO crystal block. Y1 - 2009 SN - 1082-3654 SP - 2625 EP - 2628 ER - TY - JOUR A1 - Valero, Daniel A1 - Chanson, Hubert A1 - Bung, Daniel Bernhard T1 - Robust estimators for turbulence properties assessment Y1 - 2019 SP - 1 EP - 24 ER - TY - JOUR A1 - Valero, Daniel A1 - Chanson, Hubert A1 - Bung, Daniel Bernhard T1 - Robust estimators for free surface turbulence characterization: A stepped spillway application JF - Flow Measurement and Instrumentation N2 - Robust estimators are parameters insensitive to the presence of outliers. However, they presume the shape of the variables’ probability density function. This study exemplifies the sensitivity of turbulent quantities to the use of classic and robust estimators and the presence of outliers in turbulent flow depth time series. A wide range of turbulence quantities was analysed based upon a stepped spillway case study, using flow depths sampled with Acoustic Displacement Meters as the flow variable of interest. The studied parameters include: the expected free surface level, the expected fluctuation intensity, the depth skewness, the autocorrelation timescales, the vertical velocity fluctuation intensity, the perturbations celerity and the one-dimensional free surface turbulence spectrum. Three levels of filtering were utilised prior to applying classic and robust estimators, showing that comparable robustness can be obtained either using classic estimators together with an intermediate filtering technique or using robust estimators instead, without any filtering technique. Y1 - 2020 U6 - https://doi.org/10.1016/j.flowmeasinst.2020.101809 SN - 0955-5986 VL - 76 IS - Art. 101809 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Ferrein, Alexander A1 - Jacobs, Stefan A1 - Schiffer, Stefan A1 - Beck, Daniel T1 - Robust Collision Avoidance in Unknown Domestic Environments / Jacobs, Stefan ; Ferrein, Alexander ; Schiffer, Stefan ; Beck, Daniel ; Lakemeyer, Gerhard JF - ROBOCUP 2009: ROBOT SOCCER WORLD CUP XIII Y1 - 2009 N1 - Lecture Notes in Computer Science ; 5949 SP - 116 EP - 127 PB - Springer CY - Berlin ER - TY - JOUR A1 - Vögele, Stefan A1 - Josyabhatla, Vishnu Teja A1 - Ball, Christopher A1 - Rhoden, Imke A1 - Grajewski, Matthias A1 - Rübbelke, Dirk A1 - Kuckshinrichs, Wilhelm T1 - Robust assessment of energy scenarios from stakeholders' perspectives JF - Energy N2 - Using scenarios is vital in identifying and specifying measures for successfully transforming the energy system. Such transformations can be particularly challenging and require the support of a broader set of stakeholders. Otherwise, there will be opposition in the form of reluctance to adopt the necessary technologies. Usually, processes for considering stakeholders' perspectives are very time-consuming and costly. In particular, there are uncertainties about how to deal with modifications in the scenarios. In principle, new consulting processes will be required. In our study, we show how multi-criteria decision analysis can be used to analyze stakeholders' attitudes toward transition paths. Since stakeholders differ regarding their preferences and time horizons, we employ a multi-criteria decision analysis approach to identify which stakeholders will support or oppose a transition path. We provide a flexible template for analyzing stakeholder preferences toward transition paths. This flexibility comes from the fact that our multi-criteria decision aid-based approach does not involve intensive empirical work with stakeholders. Instead, it involves subjecting assumptions to robustness analysis, which can help identify options to influence stakeholders' attitudes toward transitions. Y1 - 2023 U6 - https://doi.org/10.1016/j.energy.2023.128326 SN - 1873-6785 (Online) SN - 0360-5442 (Print) IS - In Press, Article 128326 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Heuermann, Holger A1 - Schiek, B. T1 - Robust Algorithms for Txx Network Analyzer Self-Calibration Procedures JF - IEEE transactions on instrumentation and measurement : IM / Institute of Electrical and Electronics Engineers, Instrumentation and Measurement Group. 43 (1994), H. 1 Y1 - 1994 SN - 0018-9456 SP - 18 EP - 23 ER - TY - JOUR A1 - Kirstein, Simon A1 - Müller, Karsten A1 - Walecki-Mingers, Mark A1 - Deserno, Thomas M. T1 - Robust adaptive flow line detection in sewer pipes JF - Automation in construction N2 - As part of a novel approach to automatic sewer inspection, this paper presents a robust algorithm for automatic flow line detection. A large image repository is obtained from about 50,000 m sewers to represent the high variability of real world sewer systems. Automatic image processing combines Canny edge detection, Hough transform for straight lines and cost minimization using Dijkstra's shortest path algorithm. Assuming that flow lines are mostly smoothly connected horizontal structures, piecewise flow line delineation is reduced to a process of selecting adjacent line candidates. Costs are derived from the gap between adjacent candidates and their reliability. A single parameter α enables simple control of the algorithm. The detected flow line may precisely follow the segmented edges (α = 0.0) or minimize gaps at joints (α = 1.0). Both, manual and ground truth-based analysis indicate that α = 0.8 is optimal and independent of the sewer's material. The algorithm forms an essential step to further automation of sewer inspection. Y1 - 2012 U6 - https://doi.org/10.1016/j.autcon.2011.05.009 SN - 1872-7891 (E-Journal) ; 0926-5805 (Print) IS - 21 SP - 24 EP - 31 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Ferrein, Alexander T1 - Robot controllers for highly dynamic environments with real-time constraints JF - Künstliche Intelligenz : KI. 24 (2010), H. 2 Y1 - 2010 SN - 1610-1987 SP - 175 EP - 178 ER - TY - JOUR A1 - Michaux, F. A1 - Mattern, P. A1 - Kallweit, Stephan T1 - RoboPIV: how robotics enable PIV on a large industrial scale JF - Measurement Science and Technology N2 - This work demonstrates how the interaction between particle image velocimetry (PIV) and robotics can massively increase measurement efficiency. The interdisciplinary approach is shown using the complex example of an automated, large scale, industrial environment: a typical automotive wind tunnel application. Both the high degree of flexibility in choosing the measurement region and the complete automation of stereo PIV measurements are presented. The setup consists of a combination of three robots, individually used as a 6D traversing unit for the laser illumination system as well as for each of the two cameras. Synchronised movements in the same reference frame are realised through a master-slave setup with a single interface to the user. By integrating the interface into the standard wind tunnel management system, a single measurement plane or a predefined sequence of several planes can be requested through a single trigger event, providing the resulting vector fields within minutes. In this paper, a brief overview on the demands of large scale industrial PIV and the existing solutions is given. Afterwards, the concept of RoboPIV is introduced as a new approach. In a first step, the usability of a selection of commercially available robot arms is analysed. The challenges of pose uncertainty and importance of absolute accuracy are demonstrated through comparative measurements, explaining the individual pros and cons of the analysed systems. Subsequently, the advantage of integrating RoboPIV directly into the existing wind tunnel management system is shown on basis of a typical measurement sequence. In a final step, a practical measurement procedure, including post-processing, is given by using real data and results. Ultimately, the benefits of high automation are demonstrated, leading to a drastic reduction in necessary measurement time compared to non-automated systems, thus massively increasing the efficiency of PIV measurements. Y1 - 2018 U6 - https://doi.org/10.1088/1361-6501/aab5c1 SN - 1361-6501 N1 - Special Section on the 12th International Symposium on Particle Image Velocimetry (PIV 2017) VL - 29 IS - 7 SP - 074009 PB - IOP CY - Bristol ER - TY - JOUR A1 - Ferrein, Alexander A1 - Steinbauer, Gerald A1 - McPhillips, Graeme A1 - Potgieter, Anet T1 - RoboCup Standard Platform League - Team Zadeat : an intercontinental research effort Y1 - 2008 SP - 1 EP - 7 ER - TY - JOUR A1 - Ferrein, Alexander A1 - Marais, Stephen A1 - Potgieter, Anet A1 - Steinbauer, Gerald T1 - RoboCup Junior: A vehicle for S&T education in Africa? Y1 - 2011 SN - 978-1-61284-992-8 N1 - AFRICON, 2011 SP - 1 EP - 6 PB - IEEE CY - New York ER -