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 - CHAP A1 - Baader, Fabian A1 - Reiswich, M. A1 - Bartsch, M. A1 - Keller, D. A1 - Tiede, E. A1 - Keck, G. A1 - Demircian, A. A1 - Friedrich, M. A1 - Dachwald, Bernd A1 - Schüller, K. A1 - Lehmann, R. A1 - Chojetzki, R. A1 - Durand, C. A1 - Rapp, L. A1 - Kowalski, Julia A1 - Förstner, R. T1 - VIPER - Student research on extraterrestrical ice penetration technology T2 - Proceedings of the 2nd Symposium on Space Educational Activities N2 - Recent analysis of scientific data from Cassini and earth-based observations gave evidence for a global ocean under a surrounding solid ice shell on Saturn's moon Enceladus. Images of Enceladus' South Pole showed several fissures in the ice shell with plumes constantly exhausting frozen water particles, building up the E-Ring, one of the outer rings of Saturn. In this southern region of Enceladus, the ice shell is considered to be as thin as 2 km, about an order of magnitude thinner than on the rest of the moon. Under the ice shell, there is a global ocean consisting of liquid water. Scientists are discussing different approaches the possibilities of taking samples of water, i.e. by melting through the ice using a melting probe. FH Aachen UAS developed a prototype of maneuverable melting probe which can navigate through the ice that has already been tested successfully in a terrestrial environment. This means no atmosphere and or ambient pressure, low ice temperatures of around 100 to 150K (near the South Pole) and a very low gravity of 0,114 m/s^2 or 1100 μg. Two of these influencing measures are about to be investigated at FH Aachen UAS in 2017, low ice temperature and low ambient pressure below the triple point of water. Low gravity cannot be easily simulated inside a large experiment chamber, though. Numerical simulations of the melting process at RWTH Aachen however are showing a gravity dependence of melting behavior. Considering this aspect, VIPER provides a link between large-scale experimental simulations at FH Aachen UAS and numerical simulations at RWTH Aachen. To analyze the melting process, about 90 seconds of experiment time in reduced gravity and low ambient pressure is provided by the REXUS rocket. In this time frame, the melting speed and contact force between ice and probes are measured, as well as heating power and a two-dimensional array of ice temperatures. Additionally, visual and infrared cameras are used to observe the melting process. Y1 - 2018 SP - 1 EP - 6 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 - TY - CHAP A1 - Funke, Harald A1 - Esch, Thomas A1 - Roosen, Peter ED - Bartz, Wilfried J. T1 - Using motor gasoline for aircrafts - coping with growing bio-fuel-caused risks by understanding cause-effect relationship T2 - Fuels 2009 : mineral oil based and alternative fuels ; 7th international colloquium ; January 14 - 15, 2009 N2 - The utilisation of vehicle-oriented gasoline in general aviation is very desirable for both ecological and economical reasons, as well as for general considerations of availability. As of today vehicle fuels may be used if the respective engine and cell are certified for such an operation. For older planes a supplementary technical certificate is provided for gasoline mixtures with less than 1 % v/v ethanol only, though. Larger admixtures of ethanol may lead to sudden engine malfunction and should be considered as considerable security risks. Major problems are caused by the partially ethanol non-withstanding materials, a necessarily changed stochiometric adjustment of the engine for varying ethanol shares and the tendency for phase separation in the presence of absorbed water. The concepts of the flexible fuel vehicles are only partially applicable in the view of air security. Y1 - 2009 SN - 978-3-924813-75-8 SP - 237 EP - 244 PB - Technische Akademie Esslingen (TAE) CY - Ostfildern ER - TY - JOUR A1 - Wittmann, Klaus A1 - Gillessen, F. A1 - Otto, G. A1 - Röstel, R. T1 - Undercooling and solidification of metallic melts suspended in a non-nucleating matrix: Experiment NUCAL of the German Spacelab Mission D-2 JF - Acta Astronautica. 38 (1996), H. 1 Y1 - 1996 SN - 0094-5765 SP - 63 EP - 68 ER - TY - THES A1 - Kowalski, Julia T1 - Two-phase Modeling of Debris Flows Y1 - 2008 SN - 978-3-86664-524-0 N1 - Diss., Eidgenössische Technische Hochschule ETH Zürich, Nr. 17827, 2008 PB - Mensch und Buch CY - Berlin ER - TY - CHAP A1 - Kowalski, Julia A1 - Bartelt, Perry A1 - McElwaine, J. T1 - Two-phase debris flow modeling T2 - Geophysical Research Abstracts Y1 - 2007 N1 - A-08119 ER - TY - CHAP A1 - Kowalski, Julia A1 - McElwaine, J. T1 - Two-phase debris flow modeling T2 - Geophysical Research Abstracts Y1 - 2008 N1 - A-01048 ER - TY - JOUR A1 - Esch, Thomas T1 - Trends in commercial vehicle powertrains JF - ATZautotechnology N2 - Low emission zones and truck bans, the rising price of diesel and increases in road tolls: all of these factors are putting serious pressure on the transport industry. Commercial vehicle manufacturers and their suppliers are in the process of identifying new solutions to these challenges as part of their efforts to meet the EEV (enhanced environmentally friendly vehicle) limits, which are currently the most robust European exhaust and emissions standards for trucks and buses. KW - European Transient Cycle KW - Common Rail Injection System KW - Commercial Vehicle KW - Selective Catalytic Reduction KW - Diesel Engine Y1 - 2010 U6 - http://dx.doi.org/10.1007/BF03247185 SN - 2192-886X VL - 2010 IS - 10 SP - 26 EP - 31 PB - Vieweg & Sohn CY - Wiesbaden ER - TY - JOUR A1 - Fischer, Jan-Thomas A1 - Kowalski, Julia A1 - Pudasaini, Shiva P. T1 - Topographic curvature effects in applied avalanche modelling JF - Cold Regions Science and Technology N2 - This paper describes the implementation of topographic curvature effects within the RApid Mass MovementS (RAMMS) snow avalanche simulation toolbox. RAMMS is based on a model similar to shallow water equations with a Coulomb friction relation and the velocity dependent Voellmy drag. It is used for snow avalanche risk assessment in Switzerland. The snow avalanche simulation relies on back calculation of observed avalanches. The calibration of the friction parameters depends on characteristics of the avalanche track. The topographic curvature terms are not yet included in the above mentioned classical model. Here, we fundamentally improve this model by mathematically and physically including the topographic curvature effects. By decomposing the velocity dependent friction into a topography dependent term that accounts for a curvature enhancement in the Coulomb friction, and a topography independent contribution similar to the classical Voellmy drag, we construct a general curvature dependent frictional resistance, and thus propose new extended model equations. With three site-specific examples, we compare the apparent frictional resistance of the new approach, which includes topographic curvature effects, to the classical one. Our simulation results demonstrate substantial effects of the curvature on the flow dynamics e.g., the dynamic pressure distribution along the slope. The comparison of resistance coefficients between the two models demonstrates that the physically based extension presents an improvement to the classical approach. Furthermore a practical example highlights its influence on the pressure outline in the run out zone of the avalanche. Snow avalanche dynamics modeling natural terrain curvature centrifugal force friction coefficients. KW - Snow KW - Avalanche Y1 - 2012 U6 - http://dx.doi.org/10.1016/j.coldregions.2012.01.005 SN - 1872-7441 VL - 74-75 SP - 21 EP - 30 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Weber, Tobias A1 - Arent, Jan-Christoph A1 - Steffen, Lucas A1 - Balvers, Johannes M. A1 - Duhovic, Miro T1 - Thermal optimization of composite autoclave molds using the shift factor approach for boundary condition estimation JF - Journal of Composite Materials Y1 - 2017 U6 - http://dx.doi.org/10.1177/0021998317699868 SN - 1530-793X VL - 51 IS - 12 SP - 1753 EP - 1767 PB - Sage CY - London ER - TY - CHAP A1 - Busse, Daniel A1 - Esch, Thomas A1 - Muntaniol, Roman T1 - Thermal management in E-carsharing vehicles - preconditioning concepts of passenger compartments T2 - E-Mobility in Europe : trends and good practice N2 - The issue of thermal management in electric vehicles includes the topics of drivetrain cooling and heating, interior temperature, vehicle body conditioning and safety. In addition to the need to ensure optimal thermal operating conditions of the drivetrain components (drive motor, battery and electrical components), thermal comfort must be provided for the passengers. Thermal comfort is defined as the feeling which expresses the satisfaction of the passengers with the ambient conditions in the compartment. The influencing factors on thermal comfort are the temperature and humidity as well as the speed of the indoor air and the clothing and the activity of the passengers, in addition to the thermal radiation and the temperatures of the interior surfaces. The generation and the maintenance of free visibility (ice- and moisture-free windows) count just as important as on-demand heating and cooling of the entire vehicle. A Carsharing climate concept of the innovative ec2go vehicle stipulates and allows for only seating areas used by passengers to be thermally conditioned in a close-to-body manner. To enable this, a particular feature has been added to the preconditioning of the Carsharing electric vehicle during the electric charging phase at the parking station. KW - Carsharing KW - Thermal management KW - Thermal comfort KW - Electrical vehicle KW - Passenger compartment Y1 - 2015 SN - 978-3-319-13193-1 U6 - http://dx.doi.org/10.1007/978-3-319-13194-8_18 SP - 327 EP - 343 PB - Springer CY - Cham [u.a.] ER -