TY - JOUR A1 - Möhren, Felix A1 - Bergmann, Ole A1 - Janser, Frank A1 - Braun, Carsten T1 - On the influence of elasticity on propeller performance: a parametric study JF - CEAS Aeronautical Journal N2 - The aerodynamic performance of propellers strongly depends on their geometry and, consequently, on aeroelastic deformations. Knowledge of the extent of the impact is crucial for overall aircraft performance. An integrated simulation environment for steady aeroelastic propeller simulations is presented. The simulation environment is applied to determine the impact of elastic deformations on the aerodynamic propeller performance. The aerodynamic module includes a blade element momentum approach to calculate aerodynamic loads. The structural module is based on finite beam elements, according to Timoshenko theory, including moderate deflections. Several fixed-pitch propellers with thin-walled cross sections made of both isotropic and non-isotropic materials are investigated. The essential parameters are varied: diameter, disc loading, sweep, material, rotational, and flight velocity. The relative change of thrust between rigid and elastic blades quantifies the impact of propeller elasticity. Swept propellers of large diameters or low disc loadings can decrease the thrust significantly. High flight velocities and low material stiffness amplify this tendency. Performance calculations without consideration of propeller elasticity can lead to decreased efficiency. To avoid cost- and time-intense redesigns, propeller elasticity should be considered for swept planforms and low disc loadings. KW - Propeller KW - Finite element method KW - Blade element method KW - Propeller elasticity KW - Aeroelasticity Y1 - 2023 U6 - https://doi.org/10.1007/s13272-023-00649-y SN - 1869-5590 (Online) SN - 1869-5582 (Print) N1 - Corresponding author: Felix Möhren VL - 14 SP - 311 EP - 323 PB - Springer Nature CY - Berlin ER - TY - CHAP A1 - Möhren, Felix A1 - Bergmann, Ole A1 - Janser, Frank A1 - Braun, Carsten T1 - On the determination of harmonic propeller loads T2 - AIAA SCITECH 2023 Forum N2 - Dynamic loads significantly impact the structural design of propeller blades due to fatigue and static strength. Since propellers are elastic structures, deformations and aerodynamic loads are coupled. In the past, propeller manufacturers established procedures to determine unsteady aerodynamic loads and the structural response with analytical steady-state calculations. According to the approach, aeroelastic coupling primarily consists of torsional deformations. They neglect bending deformations, deformation velocities, and inertia terms. This paper validates the assumptions above for a General Aviation propeller and a lift propeller for urban air mobility or large cargo drones. Fully coupled reduced-order simulations determine the dynamic loads in the time domain. A quasi-steady blade element momentum approach transfers loads to one-dimensional finite beam elements. The simulation results are in relatively good agreement with the analytical method for the General Aviation propeller but show increasing errors for the slender lift propeller. The analytical approach is modified to consider the induced velocities. Still, inertia and velocity proportional terms play a significant role for the lift propeller due to increased elasticity. The assumption that only torsional deformations significantly impact the dynamic loads of propellers is not valid. Adequate determination of dynamic loads of such designs requires coupled aeroelastic simulations or advanced analytical procedures. Y1 - 2023 U6 - https://doi.org/10.2514/6.2023-2404 N1 - AIAA SCITECH 2023 Forum, 23-27 January 2023, National Harbor, Md & Online PB - AIAA ER - TY - BOOK A1 - Engeln-Müllges, Gisela A1 - Uhlig, Frank T1 - Numerical algorithms with C Y1 - 1996 SN - 3-540-60530-0 PB - Springer CY - Berlin [u.a.] ER - TY - BOOK A1 - Engeln-Müllges, Gisela A1 - Uhlig, Frank T1 - Numeric Algorithms with Fortran Y1 - 1996 SN - 3-540-60529-0 PB - Springer CY - Berlin [u.a.] ER - TY - JOUR A1 - Ferrein, Alexander A1 - Dylla, Frank A1 - Lakemeyer, Gerhard A1 - Murray, Jan T1 - Approaching a formal soccer theory from behaviour specifications in robotic soccer / Dylla, Frank ; Ferrein, Alexander ; Lakemeyer, Gerhard ; Murray, Jan ; Obst, Oliver ; Röfer, Thomas ; Schiffer, Stefan ; Stolzenburg, Frieder ; Visser, Ubbo ; Wagner, Tho JF - Computers in sport / editors: P Dabnichki Y1 - 2008 SN - 978-1-8456-4064-4 SP - 161 EP - 185 PB - WIT Press CY - Southampton ER - TY - CHAP A1 - Waldmann, Christoph A1 - Vera, Jean-Pierre de A1 - Dachwald, Bernd A1 - Strasdeit, Henry A1 - Sohl, Frank A1 - Hanff, Hendrik A1 - Kowalski, Julia A1 - Heinen, Dirk A1 - Macht, Sabine A1 - Bestmann, Ulf A1 - Meckel, Sebastian A1 - Hildebrandt, Marc A1 - Funke, Oliver A1 - Gehrt, Jan-Jöran T1 - Search for life in ice-covered oceans and lakes beyond Earth T2 - 2018 IEEE/OES Autonomous Underwater Vehicle Workshop, Proceedings November 2018, Article number 8729761 N2 - The quest for life on other planets is closely connected with the search for water in liquid state. Recent discoveries of deep oceans on icy moons like Europa and Enceladus have spurred an intensive discussion about how these waters can be accessed. The challenge of this endeavor lies in the unforeseeable requirements on instrumental characteristics both with respect to the scientific and technical methods. The TRIPLE/nanoAUV initiative is aiming at developing a mission concept for exploring exo-oceans and demonstrating the achievements in an earth-analogue context, exploring the ocean under the ice shield of Antarctica and lakes like Dome-C on the Antarctic continent. KW - Planetary exploration KW - Jupiter KW - ice moons KW - underwater vehicle KW - Antarctica Y1 - 2018 U6 - https://doi.org/10.1109/AUV.2018.8729761 ER - TY - JOUR A1 - Saretzki, Charlotte A1 - Bergmann, Ole A1 - Dahmann, Peter A1 - Janser, Frank A1 - Keimer, Jona A1 - Machado, Patricia A1 - Morrison, Audry A1 - Page, Henry A1 - Pluta, Emil A1 - Stübing, Felix A1 - Küpper, Thomas T1 - Are small airplanes safe with regards to COVID-19 transmission? JF - Journal of Travel Medicine Y1 - 2021 U6 - https://doi.org/10.1093/jtm/taab105 SN - 1708-8305 VL - 28 IS - 7 PB - Oxford University Press CY - Oxford ER - TY - GEN A1 - Lindel, Tomasz Dawid A1 - Greiser, Andreas A1 - Waxman, Patrick A1 - Dietterle, Martin A1 - Seifert, Frank A1 - Fontius, Ulrich A1 - Renz, Wolfgang A1 - Dieringer, Matthias A. A1 - Frauenrath, Tobias A1 - Schulz-Menger, Jeanette A1 - Niendorf, Thoralf A1 - Ittermann, Bernd T1 - Cardiac CINE MRI at 7 T using a transmit array T2 - 2012 ISMRM Annual Meeting Proceedings N2 - With its need for high SNR and short acquisition times, Cardiac MRI (CMR) is an intriguing target application for ultrahigh field MRI. Due to the sheer size of the upper torso, however, the known RF issues of 7T MRI are also most prominent in CMR. Recent years brought substantial progress but the full potential of the ultrahigh field for CMR is yet to be exploited. Parallel transmission (pTx) is a promising approach in this context and several groups have already reported B1 shimming for 7T CMR. In such a static pTx application amplitudes and phases of all Tx channels are adjusted individually but otherwise imaging techniques established in current clinical practice 1.5 T and 3 T are applied. More advanced forms of pTx as spatially selective excitation (SSE) using Transmit SENSE promise additional benefits like faster imaging with reduced fields of view or improved SAR control. SSE requires the full dynamic capabilities of pTx, however, and for the majority of today's implemented pTx hardware the internal synchronization of the Tx array does not easily permit external triggering as needed for CMR. Here we report a software solution to this problem and demonstrate the feasibility of CINE CMR at 7 T using a Tx array. Y1 - 2012 SN - 1545-4428 N1 - ISMRM 20th Annual Meeting & Exhibition, 5-11 May 2012, Melbourne, Australia ER - TY - JOUR A1 - Weemstra, Monique A1 - Eilmann, Britta A1 - Sass-Klaassen, Ute G. W. A1 - Sterck, Frank J. T1 - Summer droughts limit tree growth across 10 temperate species on a productive forest site JF - Forest Ecology and Management Y1 - 2013 U6 - https://doi.org/doi:10.1016/j.foreco.2013.06.007 SN - 0378-1127 (Print) SN - 1872-7042 (Online) VL - 2013 IS - 306 SP - 142 EP - 149 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Dieringer, Matthias A. A1 - Renz, Wolfgang A1 - Lindel, Tomasz D. A1 - Seifert, Frank A1 - Frauenrath, Tobias A1 - von Knobelsdorf-Brenkenhoff, Florian A1 - Waiczies, Helmar A1 - Hoffmann, Werner A1 - Rieger, Jan A1 - Pfeiffer, Harald A1 - Ittermann, Bernd A1 - Schulz-Menger, Jeanette A1 - Niendorf, Thoralf T1 - Design and application of a four-channel transmit/receive surface coil for functional cardiac imaging at 7T JF - Journal of Magnetic Resonance Imaging N2 - Purpose To design and evaluate a four-channel cardiac transceiver coil array for functional cardiac imaging at 7T. Materials and Methods A four-element cardiac transceiver surface coil array was developed with two rectangular loops mounted on an anterior former and two rectangular loops on a posterior former. specific absorption rate (SAR) simulations were performed and a Burn:x-wiley:10531807:media:JMRI22451:tex2gif-stack-1 calibration method was applied prior to obtain 2D FLASH CINE (mSENSE, R = 2) images from nine healthy volunteers with a spatial resolution of up to 1 × 1 × 2.5 mm3. Results Tuning and matching was found to be better than 10 dB for all subjects. The decoupling (S21) was measured to be >18 dB between neighboring loops, >20 dB for opposite loops, and >30 dB for other loop combinations. SAR values were well within the limits provided by the IEC. Imaging provided clinically acceptable signal homogeneity with an excellent blood-myocardium contrast applying the Burn:x-wiley:10531807:media:JMRI22451:tex2gif-stack-2 calibration approach. Conclusion A four-channel cardiac transceiver coil array for 7T was built, allowing for cardiac imaging with clinically acceptable signal homogeneity and an excellent blood-myocardium contrast. Minor anatomic structures, such as pericardium, mitral, and tricuspid valves and their apparatus, as well as trabeculae, were accurately delineated. Y1 - 2011 U6 - https://doi.org/10.1002/jmri.22451 SN - 1522-2586 VL - 33 IS - 3 SP - 736 EP - 741 PB - Wiley-Liss CY - New York ER - TY - CHAP A1 - Hammer, Andreas A1 - Vieth, Matthias A1 - Maier, Frank T1 - Co-Plot as a new multivariate analysis method for operations management research? T2 - Papers of the 12th International EurOMA Conference on Operational and Global Competitiveness, Budapest, Hungary, June 19-22, 2005 / Editor: Krisztina Demeter Y1 - 2005 SN - 963-218-455-6 SP - 1007 EP - 1016 ER - TY - JOUR A1 - Eilmann, Britta A1 - Sterck, Frank J. A1 - Wegner, L. A1 - de Vries, Sven M. G. A1 - von Arx, G. A1 - Mohren, Godefridus M. J. A1 - den Ouden, Jan A1 - Sass-Klaassen, Ute G. W. T1 - Wood structural differences between northern and southern beech provenances growing at a moderate site JF - Tree Physiology Y1 - 2014 U6 - https://doi.org/10.1093/treephys/tpu069 SN - 1758-4469 (Online) SN - 0829-318X (Print) VL - 34 IS - 8 SP - 882 EP - 893 PB - Oxford University Press CY - Oxford ER - TY - JOUR A1 - Ferrein, Alexander A1 - Dylla, Frank A1 - Lakemeyer, Gerhard T1 - Acting and Deliberating using Golog in Robotic Soccer - A Hybrid Architecture / Dylla, Frank ; Ferrein, Alexander ; Lakemeyer, Gerhard JF - Proc. 3rd International Cognitive Robotics Workshop (CogRob 2002) Y1 - 2002 SP - 1 EP - 7 ER - TY - JOUR A1 - Ferrein, Alexander A1 - Dylla, Frank A1 - Lakemeyer, Gerhard A1 - Murray, Jan T1 - Towards a League-Independent Qualitative Soccer Theory for RoboCup / Dylla, Frank ; Ferrein, Alexander ; Lakemeyer, Gerhard ; Murray, Jan ; Obst, Oliver ; Röfer, Thomas ; Stolzenburg, Frieder ; Visser, Ubbo JF - RoboCup 2004: Robot Soccer World Cup VIII / Daniele Nardi ... (ed.). Y1 - 2005 SN - 978-3-540-25046-8 N1 - Lecture Notes in Computer Science ; 3276 SP - 611 EP - 618 PB - Springer CY - Berlin ER - TY - CHAP A1 - Mulsow, Niklas A. A1 - Hülsen, Benjamin A1 - Gützlaff, Joel A1 - Spies, Leon A1 - Bresser, Andreas A1 - Dabrowski, Adam A1 - Czupalla, Markus A1 - Kirchner, Frank T1 - Concept and design of an autonomous micro rover for long term lunar exploration T2 - Proceedings of the 74th International Astronautical Congress N2 - Research on robotic lunar exploration has seen a broad revival, especially since the Google Lunar X-Prize increasingly brought private endeavors into play. This development is supported by national agencies with the aim of enabling long-term lunar infrastructure for in-situ operations and the establishment of a moon village. One challenge for effective exploration missions is developing a compact and lightweight robotic rover to reduce launch costs and open the possibility for secondary payload options. Existing micro rovers for exploration missions are clearly limited by their design for one day of sunlight and their low level of autonomy. For expanding the potential mission applications and range of use, an extension of lifetime could be reached by surviving the lunar night and providing a higher level of autonomy. To address this objective, the paper presents a system design concept for a lightweight micro rover with long-term mission duration capabilities, derived from a multi-day lunar mission scenario at equatorial regions. Technical solution approaches are described, analyzed, and evaluated, with emphasis put on the harmonization of hardware selection due to a strictly limited budget in dimensions and power. Y1 - 2023 N1 - 74. International Astronautical Congress (IAC-2023), October 2-6 2023, Baku, Azerbaijan PB - dfki CY - Saarbrücken ER - TY - CHAP A1 - Hülsen, Benjamin A1 - Mulsow, Niklas A. A1 - Dabrowski, Adam A1 - Brinkmann, Wiebke A1 - Gützlaff, Joel A1 - Spies, Leon A1 - Czupalla, Markus A1 - Kirchner, Frank T1 - Towards an autonomous micro rover with night survivability for lunar exploration T2 - Proceedings of the 74th International Astronautical Congress N2 - In Europe, efforts are underway to develop key technologies that can be used to explore the Moon and to exploit the resources available. This includes technologies for in-situ resource utilization (ISRU), facilitating the possibility of a future Moon Village. The Moon is the next step for humans and robots to exploit the use of available resources for longer term missions, but also for further exploration of the solar system. A challenge for effective exploration missions is to achieve a compact and lightweight robot to reduce launch costs and open up the possibility of secondary payload options. Current micro rover concepts are primarily designed to last for one day of solar illumination and show a low level of autonomy. Extending the lifetime of the system by enabling survival of the lunar night and implementing a high level of autonomy will significantly increase potential mission applications and the operational range. As a reference mission, the deployment of a micro rover in the equatorial region of the Moon is being considered. An overview of mission parameters and a detailed example mission sequence is given in this paper. The mission parameters are based on an in-depth study of current space agency roadmaps, scientific goals, and upcoming flight opportunities. Furthermore, concepts of the ongoing international micro rover developments are analyzed along with technology solutions identified for survival of lunar nights and a high system autonomy. The results provide a basis of a concise requirements set-up to allow dedicated system developments and qualification measures in the future. Y1 - 2023 N1 - 74. International Astronautical Congress (IAC-2023), October 2-6 2023, Baku, Azerbaijan PB - dfki ER - TY - JOUR A1 - Schieren, Mark A1 - Kleinschmidt, Joris A1 - Schmutz, Axel A1 - Loop, Torsten A1 - Gatzweiler, Karl-Heinz A1 - Staat, Manfred A1 - Wappler, Frank A1 - Defosse, Jerome T1 - Comparison of forces acting on maxillary incisors during tracheal intubation with different laryngoscopy techniques: a blinded manikin study JF - Anaesthesia Y1 - 2019 SN - 1365-2044 U6 - https://doi.org/10.1111/anae.14815 N1 - Die Anhänge "Table S1 (Impact of sex and level of training on dental force. Results presented as median (IQR [range]) and n (%))" und "Appendix S1 (Measurement technique.)" stehen unter "Supporting Information" zum Download bereit. VL - 74 IS - 12 PB - Wiley-Blackwell CY - Oxford ER - TY - GEN A1 - Dieringer, Matthias A. A1 - Renz, Wolfgang A1 - Lindel, Tomasz A1 - Seifert, Frank A1 - Frauenrath, Tobias A1 - Waiczies, Helmar A1 - von Knobelsdorff-Brenkhoff, Florian A1 - Santoro, Davide A1 - Hoffmann, Werner A1 - Ittermann, Bernd A1 - Schulz-Menger, Jeanette A1 - Niendorf, Thoralf T1 - 4CH TX/RX Surface Coil for 7T: Design, Optimization and Application for Cardiac Function Imaging T2 - 2010 ISMRM-ESMRMB joint annual meeting N2 - Practical impediments of ultra high field cardiovascular MR (CVMR) can be catalogued in exacerbated magnetic field and radio frequency (RF) inhomogeneities, susceptibility and off-resonance effects, conductive and dielectric effects in tissue, and RF power deposition constraints, which all bear the potential to spoil the benefit of CVMR at 7T. Therefore, a four element cardiac transceive surface coil array was developed. Cardiac imaging provided clinically acceptable signal homogeneity with an excellent blood myocardium contrast. Subtle anatomic structures, such as pericardium, mitral and tricuspid valves and their apparatus, papillary muscles, and trabecles were accurately delineated. Y1 - 2010 SN - 1545-4428 N1 - ISMRM-ESMRMB joint annual meeting, 1 - 7 May 2010, Stockholm, Sweden ER - TY - JOUR A1 - Luisier, Raphaëlle A1 - Lempiäinen, Harri A1 - Scherbichler, Nina A1 - Braeuning, Albert A1 - Geissler, Miriam A1 - Dubost, Valerie A1 - Müller, Arne A1 - Scheer, Nico A1 - Chibout, Salah-Dine A1 - Hara, Hisanori A1 - Picard, Frank A1 - Theil, Diethilde A1 - Couttet, Philippe A1 - Vitobello, Antonio A1 - Grenet, Olivier A1 - Grasl-Kraupp, Bettina A1 - Ellinger-Ziegelbauer, Heidrung A1 - Thomson, John P. A1 - Meehan, Richard R. A1 - Elcombe, Clifford R. A1 - Henderson, Colin J. A1 - Wolf, C. Roland A1 - Schwarz, Michael A1 - Moulin, Pierre A1 - Terranova, Remi A1 - Moggs, Jonathan G. T1 - Phenobarbital Induces Cell Cycle Transcriptional Responses in Mouse Liver Humanized for Constitutive Androstane and Pregnane X Receptors JF - Toxicological Sciences N2 - The constitutive androstane receptor (CAR) and the pregnane X receptor (PXR) are closely related nuclear receptors involved in drug metabolism and play important roles in the mechanism of phenobarbital (PB)-induced rodent nongenotoxic hepatocarcinogenesis. Here, we have used a humanized CAR/PXR mouse model to examine potential species differences in receptor-dependent mechanisms underlying liver tissue molecular responses to PB. Early and late transcriptomic responses to sustained PB exposure were investigated in liver tissue from double knock-out CAR and PXR (CARᴷᴼ-PXRᴷᴼ), double humanized CAR and PXR (CARʰ-PXRʰ), and wild-type C57BL/6 mice. Wild-type and CARʰ-PXRʰ mouse livers exhibited temporally and quantitatively similar transcriptional responses during 91 days of PB exposure including the sustained induction of the xenobiotic response gene Cyp2b10, the Wnt signaling inhibitor Wisp1, and noncoding RNA biomarkers from the Dlk1-Dio3 locus. Transient induction of DNA replication (Hells, Mcm6, and Esco2) and mitotic genes (Ccnb2, Cdc20, and Cdk1) and the proliferation-related nuclear antigen Mki67 were observed with peak expression occurring between 1 and 7 days PB exposure. All these transcriptional responses were absent in CARᴷᴼ-PXRᴷᴼ mouse livers and largely reversible in wild-type and CARʰ-PXRʰ mouse livers following 91 days of PB exposure and a subsequent 4-week recovery period. Furthermore, PB-mediated upregulation of the noncoding RNA Meg3, which has recently been associated with cellular pluripotency, exhibited a similar dose response and perivenous hepatocyte-specific localization in both wild-type and CARʰ-PXRʰ mice. Thus, mouse livers coexpressing human CAR and PXR support both the xenobiotic metabolizing and the proliferative transcriptional responses following exposure to PB. Y1 - 2014 U6 - https://doi.org/https://doi.org/10.1093/toxsci/kfu038 SN - 1094-2025 VL - 139 IS - 2 SP - 501 EP - 511 PB - Oxford University Press CY - Oxford ER -