@article{BlomeChuHoelletal.1988, author = {Blome, Hans-Joachim and Chu, Y. and Hoell, J and Priester, W.}, title = {On the observational discrimination of Friedmann-Lema{\^i}tre models}, series = {Large Scale Structures of the Universe: Proceedings of the 130th Symposium of the International Astronomical Union, dedicated to the memory of Marc A. Aaronson (1950-1987) held in Balatonfured, Hungary, June 15-20, 1987. Edited by Jean Audouze, Marie-Christine Pelletan and Sandor Szalay.}, journal = {Large Scale Structures of the Universe: Proceedings of the 130th Symposium of the International Astronomical Union, dedicated to the memory of Marc A. Aaronson (1950-1987) held in Balatonfured, Hungary, June 15-20, 1987. Edited by Jean Audouze, Marie-Christine Pelletan and Sandor Szalay.}, publisher = {Kluwer Academic Publishers}, address = {Dordrecht}, isbn = {90-277-2742-2}, pages = {517}, year = {1988}, language = {en} } @article{HelsperNiessner1985, author = {Helsper, Christoph and Nießner, R.}, title = {On the Influence of the Vapour Substance on the Behaviour of an Expansion Type Condensation Nucleus Counter}, series = {Journal of Aerosol Science. 16 (1985), H. 5}, journal = {Journal of Aerosol Science. 16 (1985), H. 5}, isbn = {0021-8502}, pages = {457 -- 461}, year = {1985}, language = {en} } @article{BergmannMoehrenBraunetal.2023, author = {Bergmann, Ole and M{\"o}hren, Felix and Braun, Carsten and Janser, Frank}, title = {On the influence of elasticity on swept propeller noise}, series = {AIAA SCITECH 2023 Forum}, journal = {AIAA SCITECH 2023 Forum}, publisher = {AIAA}, address = {Reston, Va.}, doi = {10.2514/6.2023-0210}, year = {2023}, abstract = {High aerodynamic efficiency requires propellers with high aspect ratios, while propeller sweep potentially reduces noise. Propeller sweep and high aspect ratios increase elasticity and coupling of structural mechanics and aerodynamics, affecting the propeller performance and noise. Therefore, this paper analyzes the influence of elasticity on forward-swept, backward-swept, and unswept propellers in hover conditions. A reduced-order blade element momentum approach is coupled with a one-dimensional Timoshenko beam theory and Farassat's formulation 1A. The results of the aeroelastic simulation are used as input for the aeroacoustic calculation. The analysis shows that elasticity influences noise radiation because thickness and loading noise respond differently to deformations. In the case of the backward-swept propeller, the location of the maximum sound pressure level shifts forward by 0.5 °, while in the case of the forward-swept propeller, it shifts backward by 0.5 °. Therefore, aeroacoustic optimization requires the consideration of propeller deformation.}, language = {en} } @article{FoersterMorvicBetko1998, author = {F{\"o}rster, Arnold and Morvic, M. and Betko, J.}, title = {On the hopping and band conductivity in molecular-beam epitaxial low-temperature grown GaAs / M. Morvic ; J. Betko ; J. Nov{\´a}k ... A. F{\"o}rster}, series = {Physica status solidi / B, Basic research. 205 (1998), H. 1}, journal = {Physica status solidi / B, Basic research. 205 (1998), H. 1}, isbn = {1521-3951}, pages = {125 -- 128}, year = {1998}, language = {en} } @article{Zastrow1985, author = {Zastrow, Udo}, title = {On the formulation of the fundamental solutions for orthotropic plane elasticity}, series = {Acta Mechanica. 57 (1985), H. 3-4}, journal = {Acta Mechanica. 57 (1985), H. 3-4}, isbn = {1619-6937}, pages = {113 -- 122}, year = {1985}, language = {en} } @article{GoettenFingerHavermannetal.2018, author = {G{\"o}tten, Falk and Finger, Felix and Havermann, Marc and Braun, Carsten and Gomez, Francisco and Bill, C.}, title = {On the flight performance impact of landing gear drag reduction methods for unmanned air vehicles}, series = {Deutscher Luft- und Raumfahrtkongress 2018}, journal = {Deutscher Luft- und Raumfahrtkongress 2018}, publisher = {DGLR}, address = {Bonn}, doi = {10.25967/480058}, pages = {11 S.}, year = {2018}, abstract = {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.}, language = {en} } @article{ZastrowHackl1988, author = {Zastrow, Udo and Hackl, Klaus}, title = {On the existence, uniqueness and completeness of displacements and stress functions in linear elasticity / Hackl, Klaus ; Zastrow, Udo}, series = {Journal of Elasticity. 19 (1988), H. 1}, journal = {Journal of Elasticity. 19 (1988), H. 1}, isbn = {1573-2681}, pages = {3 -- 23}, year = {1988}, language = {en} } @article{SommerGerlingPredel1984, author = {Sommer, Ferdinand and Gerling, Ulrich and Predel, Bruno}, title = {On the evaluation of interchange energies and the equilibrium-constant from mixing enthalpies of a regular associated solution-comment}, series = {Zeitschrift f{\"u}r Metallkunde : international journal of materials research and advanced techniques. Bd. 75, H. 11}, journal = {Zeitschrift f{\"u}r Metallkunde : international journal of materials research and advanced techniques. Bd. 75, H. 11}, issn = {0044-3093 ; 0179-4841}, pages = {898}, year = {1984}, language = {en} } @article{ZhangValeroBungetal.2018, author = {Zhang, G. and Valero, Daniel and Bung, Daniel Bernhard and Chanson, H.}, title = {On the estimation of free-surface turbulence using ultrasonic sensors}, series = {Flow Measurement and Instrumentation}, volume = {60}, journal = {Flow Measurement and Instrumentation}, publisher = {Elsevier}, address = {Amsterdam}, issn = {0955-5986}, doi = {10.1016/j.flowmeasinst.2018.02.009}, pages = {171 -- 184}, year = {2018}, abstract = {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.}, language = {en} } @article{Weigand1993, author = {Weigand, Christoph}, title = {On the Effects of SPC on Production Time}, series = {Economic Quality Control. 8 (1993)}, journal = {Economic Quality Control. 8 (1993)}, isbn = {0940-5151}, pages = {23 -- 61}, year = {1993}, language = {en} }