TY - JOUR A1 - Overduin, James A1 - Blome, Hans-Joachim A1 - Hoell, Josef T1 - Wolfgang Priester: from the big bounce to the Lambda-dominated universe JF - Naturwissenschaften Y1 - 2007 SN - 0028-1042 VL - 94 IS - 6 SP - 417 EP - 429 ER - TY - CHAP A1 - Spohr, A. A1 - Schirra, Julian A1 - Hoefling, J. A1 - Schedl, A. T1 - Wing weight estimation methodology for highly non-planar lifting systems during conceptual design T2 - Deutscher Luft- und Raumfahrtkongress 2013 : 10.9. - 12.9.2013, Stuttgart Y1 - 2013 SP - Publ. online 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 - http://dx.doi.org/10.2514/1.C035422 SN - 1533-3868 VL - 57 IS - 4 PB - AIAA CY - Reston, Va. ER - TY - JOUR A1 - Götten, Falk A1 - Havermann, Marc A1 - Braun, Carsten A1 - Marino, Matthew A1 - Bil, Cees T1 - Wind-tunnel and CFD investigations of UAV landing gears and turrets – Improvements in empirical drag estimation JF - Aerospace Science and Technology N2 - This paper analyzes the drag characteristics of several landing gear and turret configurations that are representative of unmanned aircraft tricycle landing gears and sensor turrets. A variety of these components were constructed via 3D-printing and analyzed in a wind-tunnel measurement campaign. Both turrets and landing gears were attached to a modular fuselage that supported both isolated components and multiple components at a time. Selected cases were numerically investigated with a Reynolds-averaged Navier-Stokes approach that showed good accuracy when compared to wind-tunnel data. The drag of main gear struts could be significantly reduced via streamlining their cross-sectional shape and keeping load carrying capabilities similar. The attachment of wheels introduced interference effects that increased strut drag moderately but significantly increased wheel drag compared to isolated cases. Very similar behavior was identified for front landing gears. The drag of an electro-optical and infrared sensor turret was found to be much higher than compared to available data of a clean hemisphere-cylinder combination. This turret drag was merely influenced by geometrical features like sensor surfaces and the rotational mechanism. The new data of this study is used to develop simple drag estimation recommendations for main and front landing gear struts and wheels as well as sensor turrets. These recommendations take geometrical considerations and interference effects into account. Y1 - 2020 U6 - http://dx.doi.org/10.1016/j.ast.2020.106306 SN - 1270-9638 VL - 107 IS - Art. 106306 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Schmitz, Günter A1 - Schmitt, H.J. A1 - Dammann, H. T1 - Weakly Guiding Semileaky Isolator with a Form-Birefringent Top Layer JF - Conference on Lasers and Electro-Optics ; (5, 1985, Baltimore, Md.) ; Conference on Lasers and Electro-Optics (CLEO '85) ; (1985.05.21-24 ; Baltimore, Md.) Y1 - 1985 SP - 260 PB - Optical Society of America CY - Washington, DC ER - TY - JOUR A1 - Schirra, Julian A1 - Bissonnette, William A1 - Bramesfeld, Götz T1 - Wake-model effects on induced drag prediction of staggered boxwings JF - Aerospace Y1 - 2018 U6 - http://dx.doi.org/10.3390/aerospace5010014 SN - 2226-4310 VL - 5 IS - 1 ER - TY - JOUR A1 - Mathiak, Gerhard A1 - Willnecker, Rainer A1 - Plescher, Engelbert T1 - Vibrational effects on diffusion experiments JF - Microgravity science and technology : international journal for microgravity research and applications Y1 - 2005 SN - 0938-0108 VL - Vol. 15 IS - No. 1 SP - 295 EP - 300 ER - TY - JOUR A1 - Heierli, Joachim A1 - Purves, Ross S. A1 - Felber, Andreas A1 - Kowalski, Julia T1 - Verification of nearest-neighbours interpretations in avalanche forecasting JF - Annals of Glaciology N2 - This paper examines the positive and negative aspects of a range of interpretations of nearest-neighbours models. Measures-oriented and distributionoriented verification methods are applied to categorial, probabilistic and descriptive interpretations of nearest neighbours used operationally in avalanche forecasting in Scotland and Switzerland. The dependence of skill and accuracy measures on base rate is illustrated. The purpose of the forecast and the definition of events are important variables in determining the quality of the forecast. A discussion of the application of different interpretations in operational avalanche forecasting is presented. KW - avalanche Y1 - 2004 SN - 1727-5644 VL - 38 IS - 1 SP - 84 EP - 88 ER - TY - JOUR A1 - German, Laura A1 - Mikucki, Jill A. A1 - Welch, Susan A. A1 - Welch, Kathleen A. A1 - Lutton, Anthony A1 - Dachwald, Bernd A1 - Kowalski, Julia A1 - Heinen, Dirk A1 - Feldmann, Marco A1 - Francke, Gero A1 - Espe, Clemens A1 - Lyons, W. Berry T1 - Validation of sampling antarctic subglacial hypersaline waters with an electrothermal ice melting probe (IceMole) for environmental analytical geochemistry JF - International Journal of Environmental Analytical Chemistry N2 - Geochemical characterisation of hypersaline waters is difficult as high concentrations of salts hinder the analysis of constituents at low concentrations, such as trace metals, and the collection of samples for trace metal analysis in natural waters can be easily contaminated. This is particularly the case if samples are collected by non-conventional techniques such as those required for aquatic subglacial environments. In this paper we present the first analysis of a subglacial brine from Taylor Valley, (~ 78°S), Antarctica for the trace metals: Ba, Co, Mo, Rb, Sr, V, and U. Samples were collected englacially using an electrothermal melting probe called the IceMole. This probe uses differential heating of a copper head as well as the probe’s sidewalls and an ice screw at the melting head to move through glacier ice. Detailed blanks, meltwater, and subglacial brine samples were collected to evaluate the impact of the IceMole and the borehole pump, the melting and collection process, filtration, and storage on the geochemistry of the samples collected by this device. Comparisons between melt water profiles through the glacier ice and blank analysis, with published studies on ice geochemistry, suggest the potential for minor contributions of some species Rb, As, Co, Mn, Ni, NH4+, and NO2−+NO3− from the IceMole. The ability to conduct detailed chemical analyses of subglacial fluids collected with melting probes is critical for the future exploration of the hundreds of deep subglacial lakes in Antarctica. Y1 - 2021 U6 - http://dx.doi.org/10.1080/03067319.2019.1704750 SN - 0306-7319 VL - 101 IS - 15 SP - 2654 EP - 2667 PB - Taylor & Francis CY - London ER - TY - JOUR A1 - Blome, Hans-Joachim A1 - Priester, Wolfgang T1 - Vacuum energy in cosmic dynamics JF - Astrophysics and Space Science. 117 (1985), H. 2 Y1 - 1985 SN - 0004-640X SP - 327 EP - 335 ER -