TY - JOUR A1 - Dankelmann, Peter A1 - Hellwig, Angelika A1 - Volkmann, Lutz T1 - On the connectivity of diamond-free graphs JF - Discrete applied mathematics Y1 - 2007 SN - 0166-218X (E-Journal); 1872-6771 (E-Journal); 0166-218X (Print) VL - Vol. 155 IS - Iss. 16 SP - 2111 EP - 2117 ER - TY - JOUR A1 - Heuermann, Holger A1 - Sadeghfam, Arash T1 - On the design of multimode integrated circuits in multilayered processes / Sadeghfam, A. ; Heuermann, H. JF - European Microwave Conference, 2007, 9-12 Oct. 2007 Y1 - 2007 SN - 978-2-87487-001-9 N1 - EuMC 2007 ; European Microwave Conference ; (37 : ; 2007.10.09-12 : ; Munich) SP - 516 EP - 519 ER - TY - JOUR A1 - Weigand, Christoph T1 - On the Effects of SPC on Production Time JF - Economic Quality Control. 8 (1993) Y1 - 1993 SN - 0940-5151 SP - 23 EP - 61 ER - TY - JOUR A1 - Zhang, G. A1 - Valero, Daniel A1 - Bung, Daniel Bernhard A1 - Chanson, H. T1 - On the estimation of free-surface turbulence using ultrasonic sensors JF - Flow Measurement and Instrumentation N2 - Accurate determination of free-surface dynamics has attracted much research attention during the past decade and has important applications in many environmental and water related areas. In this study, the free-surface dynamics in several turbulent flows commonly found in nature were investigated using a synchronised setup consisting of an ultrasonic sensor and a high-speed video camera. Basic sensor capabilities were examined in dry conditions to allow for a better characterisation of the present sensor model. The ultrasonic sensor was found to adequately reproduce free-surface dynamics up to the second order, especially in two-dimensional scenarios with the most energetic modes in the low frequency range. The sensor frequency response was satisfactory in the sub-20 Hz band, and its signal quality may be further improved by low-pass filtering prior to digitisation. The application of the USS to characterise entrapped air in high-velocity flows is also discussed. Y1 - 2018 U6 - https://doi.org/10.1016/j.flowmeasinst.2018.02.009 SN - 0955-5986 VL - 60 SP - 171 EP - 184 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Sommer, Ferdinand A1 - Gerling, Ulrich A1 - Predel, Bruno T1 - On the evaluation of interchange energies and the equilibrium-constant from mixing enthalpies of a regular associated solution-comment JF - Zeitschrift für Metallkunde : international journal of materials research and advanced techniques. Bd. 75, H. 11 Y1 - 1984 SN - 0044-3093 ; 0179-4841 SP - 898 ER - TY - JOUR A1 - Zastrow, Udo A1 - Hackl, Klaus T1 - On the existence, uniqueness and completeness of displacements and stress functions in linear elasticity / Hackl, Klaus ; Zastrow, Udo JF - Journal of Elasticity. 19 (1988), H. 1 Y1 - 1988 SN - 1573-2681 SP - 3 EP - 23 ER - TY - JOUR A1 - Götten, Falk A1 - Finger, Felix A1 - Havermann, Marc A1 - Braun, Carsten A1 - Gomez, Francisco A1 - Bill, C. T1 - On the flight performance impact of landing gear drag reduction methods for unmanned air vehicles JF - Deutscher Luft- und Raumfahrtkongress 2018 N2 - The flight performance impact of three different landing gear configurations on a small, fixed-wing UAV is analyzed with a combination of RANS CFD calculations and an incremental flight performance algorithm. A standard fixed landing gear configuration is taken as a baseline, while the influence of retracting the landing gear or applying streamlined fairings is investigated. A retraction leads to a significant parasite drag reduction, while also fairings promise large savings. The increase in lift-to-drag ratio is reduced at high lift coefficients due to the influence of induced drag. All configurations are tested on three different design missions with an incremental flight performance algorithm. A trade-off study is performed using the retracted or faired landing gear's weight increase as a variable. The analysis reveals only small mission performance gains as the aerodynamic improvements are negated by weight penalties. A new workflow for decision-making is presented that allows to estimate if a change in landing gear configuration is beneficial for a small UAV. Y1 - 2018 U6 - https://doi.org/10.25967/480058 PB - DGLR CY - Bonn ER - TY - JOUR A1 - Zastrow, Udo T1 - On the formulation of the fundamental solutions for orthotropic plane elasticity JF - Acta Mechanica. 57 (1985), H. 3-4 Y1 - 1985 SN - 1619-6937 SP - 113 EP - 122 ER - TY - JOUR A1 - Förster, Arnold A1 - Morvic, M. A1 - Betko, J. T1 - On the hopping and band conductivity in molecular-beam epitaxial low-temperature grown GaAs / M. Morvic ; J. Betko ; J. Novák ... A. Förster JF - Physica status solidi / B, Basic research. 205 (1998), H. 1 Y1 - 1998 SN - 1521-3951 SP - 125 EP - 128 ER - 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 -