TY - JOUR A1 - Jansen, S. V. A1 - Behbahani, Mehdi A1 - Laumen, M. A1 - Kaufmann, T. A1 - Hormes, M. A1 - Behr, M. A1 - Schmitz-Rode, T. A1 - Steinseifer, U. T1 - Investigation of Steady Flow Through a Realistic Model of the Thoracic Human Aorta Using 3D Stereo PIV and CFD-Simulation JF - ASAIO Journal Y1 - 2010 U6 - https://doi.org/10.1097/01.mat.0000369377.65122.a3 N1 - American Society of Artificial Organs (ASAIO), Baltimore, USA, May 27-29, 2010 VL - 56 IS - 2 SP - 98 PB - Lippincott Williams & Wilkins CY - Philadelphia ER - TY - JOUR A1 - Behbahani, Mehdi A1 - Nam, J. A1 - Waluga, C. A1 - Behr, M. A1 - Pasquali, M. A1 - Mottaghy, K. T1 - Modeling and Numerical Analysis of Platelet Activation, Adhesion and Aggregation in Artificial Organs Y1 - 2010 U6 - https://doi.org/10.1097/01.mat.0000369377.65122.a3 N1 - Posterpresentation American Society of Artificial Organs (ASAIO), Baltimore, USA, May 27-29, 2010 VL - 56 IS - 2 SP - 85 PB - Lippincott Williams & Wilkins CY - Philadelphia 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, Raphael 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 - Baroud, Gamal A1 - Wu, J.Z. A1 - Bohner, M A1 - Sponagel, Stefan A1 - Steffen, T. T1 - How to determine the permeability for cement infiltration into osteoporotic cancellous bone JF - Medical Engineering & Physics. 25 (2003), H. 4 N2 - Cement augmentation is an emerging surgical procedure in which bone cement is used to infiltrate and reinforce osteoporotic vertebrae. Although this infiltration procedure has been widely applied, it is performed empirically and little is known about the flow characteristics of cement during the injection process. We present a theoretical and experimental approach to investigate the intertrabecular bone permeability during the infiltration procedure. The cement permeability was considered to be dependent on time, bone porosity, and cement viscosity in our analysis. In order to determine the time-dependent permeability, ten cancellous bone cores were harvested from osteoporotic vertebrae, infiltrated with acrylic cement at a constant flow rate, and the pressure drop across the cores during the infiltration was measured. The viscosity dependence of the permeability was determined based on published experimental data. The theoretical model for the permeability as a function of bone porosity and time was then fit to the testing data. Our findings suggest that the intertrabecular bone permeability depends strongly on time. For instance, the initial permeability (60.89 mm4/N.s) reduced to approximately 63% of its original value within 18 seconds. This study is the first to analyze cement flow through osteoporotic bone. The theoretical and experimental models provided in this paper are generic. Thus, they can be used to systematically study and optimize the infiltration process for clinical practice. KW - Osteoporose KW - Permeabilität KW - Viskose Strömung KW - Viskosität KW - Vertebroplastie KW - Cement infiltration KW - Vertebroplasty KW - Osteoporosis KW - Permeability KW - Experiment KW - Analysis KW - Viscous flow Y1 - 2003 SN - 1350-4533 SP - 283 EP - 288 ER - TY - JOUR A1 - Maiwald, Volker A1 - Dachwald, Bernd T1 - Mission design for a multiple-rendezvous mission to Jupiter's trojans N2 - In this paper, we will provide a feasible mission design for a multiple-rendezvous mission to Jupiter's Trojans. It is based on solar electric propulsion, as being currently used on the DAWN spacecraft, and other flight-proven technology. First, we have selected a set of mission objectives, the prime objective being the detection of water -especially subsurface water -to provide evidence for the Trojans' formation at large solar distances. Based on DAWN and other comparable missions, we have determined suitable payload instruments to achieve these objectives. Afterwards, we have designed a spacecraft that is able to carry the selected payload to the Trojan region and rendezvous successively with three target bodies within a maximum mission duration of 15 years. Accurate low-thrust trajectories have been obtained with a global low-thrust trajectory optimization program (InTrance). During the transfer from Earth to the first target, the spacecraft is propelled by two RIT-22 ion engines from EADS Astrium, whereas a single RIT-15 is used for transfers within the Trojan region to reduce the required power. For power generation, the spacecraft uses a multi-junction solar array that is supported by concentrators. To achieve moderate mission costs, we have restricted the launch mass to a maximum of 1600 kg, the maximum interplanetary injection capability of a Soyuz/Fregat launcher. Our final layout has a mass of 1400 kg, yielding a margin of about 14%. Nestor (a member of the L4-population) was determined as the first mission target. It can be reached within 4.6 years from launch. The fuel mass ratio for this transfer is about 35%. The stay time at Nestor is 1.2 years. Eurymedon was selected as the second target (transfer time 3.5 years, stay time 3.0 years) and Irus as the third target (transfer time 2.2 years). The transfers within the Trojan L4-population can be accomplished with fuel mass ratios of about 3% for each trajectory leg. Including the stay times in orbit around the targets, the mission can be accomplished within a total duration of about 14.5 years. According to our mission analysis, it is also feasible to fly to the L5-population with similar flight times. It has to be noted that -for a first analysis -we have taken only the named targets into account. Allowing also rendezvous with unnamed objects will very likely decrease the mission duration. Based on a scaling of DAWN's mission costs (due to comparable scientific instruments and mission objectives), and taking into account the longer mission duration and the potential re-use of already developed technology, we have estimated that these three rendezvous can be accomplished with a budget of about 250 Million Euros, i.e. about 25% of ROSETTA's budget. Y1 - 2010 N1 - 38th COSPAR Scientific Assembly. Held 18-15 July 2010,Bremen, Germany SP - 3 ER - TY - JOUR A1 - Behbahani, Mehdi A1 - Probst, M. A1 - Mai, A. A1 - Tran, L. A1 - Vonderstein, K. A1 - Keschenau, P. A1 - Linde, T. A1 - Steinseifer, U. A1 - Behr, M. A1 - Mottaghy, K. T1 - The influence of high shear on thrombosis and hemolysis in artificial organs JF - The International Journal of Artificial Organs Y1 - 2010 SN - 0391-3988 VL - 33 IS - 7 SP - 426 EP - 426 PB - Sage CY - Thousand Oaks ER - TY - JOUR A1 - Sponagel, Stefan A1 - Baroud, Gamal A1 - Falk, R. A1 - Crookshank, M. T1 - Experimental and theoretical investigation of directional permeability of human vertebral cancellous bone for cement infiltration. G. Baroud, R. Falk, M. Crookshank, S. Sponagel, T. Steffen JF - Journal of Biomechanics. 37 (2004), H. 2 Y1 - 2004 SN - 0021-9290 SP - 189 EP - 196 ER - TY - CHAP A1 - Grundmann, Jan Thimo A1 - Bauer, Waldemar A1 - Borchers, Kai A1 - Dumont, Etienne A1 - Grimm, Christian D. A1 - Ho, Tra-Mi A1 - Jahnke, Rico A1 - Koch, Aaron D. A1 - Lange, Caroline A1 - Maiwald, Volker A1 - Meß, Jan-Gerd A1 - Mikulz, Eugen A1 - Quantius, Dominik A1 - Reershemius, Siebo A1 - Renger, Thomas A1 - Sasaki, Kaname A1 - Seefeldt, Patric A1 - Spietz, Peter A1 - Spröwitz, Tom A1 - Sznajder, Maciej A1 - Toth, Norbert A1 - Ceriotti, Matteo A1 - McInnes, Colin A1 - Peloni, Alessandro A1 - Biele, Jens A1 - Krause, Christian A1 - Dachwald, Bernd A1 - Hercik, David A1 - Lichtenheldt, Roy A1 - Wolff, Friederike A1 - Koncz, Alexander A1 - Pelivan, Ivanka A1 - Schmitz, Nicole A1 - Boden, Ralf A1 - Riemann, Johannes A1 - Seboldt, Wolfgang A1 - Wejmo, Elisabet A1 - Ziach, Christian A1 - Mikschl, Tobias A1 - Montenegro, Sergio A1 - Ruffer, Michael A1 - Cordero, Federico A1 - Tardivel, Simon T1 - Solar sails for planetary defense & high-energy missions T2 - IEEE Aerospace Conference Proceedings N2 - 20 years after the successful ground deployment test of a (20 m) 2 solar sail at DLR Cologne, and in the light of the upcoming U.S. NEAscout mission, we provide an overview of the progress made since in our mission and hardware design studies as well as the hardware built in the course of our solar sail technology development. We outline the most likely and most efficient routes to develop solar sails for useful missions in science and applications, based on our developed `now-term' and near-term hardware as well as the many practical and managerial lessons learned from the DLR-ESTEC Gossamer Roadmap. Mission types directly applicable to planetary defense include single and Multiple NEA Rendezvous ((M)NR) for precursor, monitoring and follow-up scenarios as well as sail-propelled head-on retrograde kinetic impactors (RKI) for mitigation. Other mission types such as the Displaced L1 (DL1) space weather advance warning and monitoring or Solar Polar Orbiter (SPO) types demonstrate the capability of near-term solar sails to achieve asteroid rendezvous in any kind of orbit, from Earth-coorbital to extremely inclined and even retrograde orbits. Some of these mission types such as SPO, (M)NR and RKI include separable payloads. For one-way access to the asteroid surface, nanolanders like MASCOT are an ideal match for solar sails in micro-spacecraft format, i.e. in launch configurations compatible with ESPA and ASAP secondary payload platforms. Larger landers similar to the JAXA-DLR study of a Jupiter Trojan asteroid lander for the OKEANOS mission can shuttle from the sail to the asteroids visited and enable multiple NEA sample-return missions. The high impact velocities and re-try capability achieved by the RKI mission type on a final orbit identical to the target asteroid's but retrograde to its motion enables small spacecraft size impactors to carry sufficient kinetic energy for deflection. Y1 - 2019 U6 - https://doi.org/10.1109/AERO.2019.8741900 N1 - AERO 2019; Big Sky; United States; 2 March 2019 through 9 March 2019 SP - 1 EP - 21 ER - TY - JOUR A1 - Digel, Ilya A1 - Wehlitz, V. A1 - Kayser, Peter A1 - Figiel-Lange, A. A1 - Bassam, Rasha A1 - Rundstedt, F. von T1 - Suspension depletion approach for exemption of infected Solanum jasminoides cells from pospiviroids JF - Plant Pathology N2 - Despite numerous studies, viroid elimination from infected plants remains a very challenging task. This study introduces for the first time a novel ‘suspension depletion’ approach for exemption of Solanum jasminoides plants from viroids. The proposed method implies initial establishment of suspension cultures of the infected plant cells. The suspended cells were then physically treated (mild thermotherapy, 33 °C), which presumably delayed the replication of the viroid. The viroid concentration in the treated biomass was monitored weekly using pospiviroid-specific PCR. After 10–12 weeks of continuous treatment, a sufficient decrease in viroid concentration was observed such that the infection became undetectable by PCR. The treated single cells then gave rise to microcolonies on a solid culture medium and the obtained viroid-negative clones were further promoted to regenerate into viroid-free plants. Three years of accumulated experimental data suggests feasibility, broad applicability, and good efficacy of the proposed approach. Y1 - 2018 U6 - https://doi.org/10.1111/ppa.12750 SN - 1365-3059 VL - 67 IS - 2 SP - 358 EP - 365 PB - Wiley CY - Oxford ER - TY - JOUR A1 - Staat, Manfred A1 - Baroud, Gamal A1 - Topcu, M. A1 - Sponagel, Stefan T1 - Soft Materials in Technology and Biology – Characteristics, Properties, and Parameter Identification JF - Bioengineering in Cell and Tissue Research / Artmann, Gerhard M. ; Chien, Shu (Eds.) Y1 - 2008 SN - 978-3-540-75408-4 SP - 253 EP - 315 PB - Springer CY - Berlin ER - TY - JOUR A1 - Temiz Artmann, Aysegül A1 - Yalcin, Ozlem A1 - Resmi, Halil A1 - Başkurt, Oǧuz Kerim T1 - Can white blood cell activation be one of the major factors that affect hemorheological parameters during and after exercise? JF - Clinical Hemorheology and Microcirculation. 26 (2002), H. 3 Y1 - 2002 SN - 1386-0291 N1 - = The 11th European Symposium on Clinical Hemorheology, Rouen, France, 19-22 September 2000 SP - 189 EP - 193 ER - TY - JOUR A1 - Sponagel, Stefan A1 - Baroud, Gamal A1 - Falk, R. A1 - Crookshank, M. T1 - Corrigendum to “Experimental and theoretical investigation of directional permeability of human vertebral cancellous bone for cement infiltration”. Baroud, G.; Falk, R.; Crookshank, M.; Sponagel, S.; Steffen, T. JF - Journal of Biomechanics. 37 (2004), H. 2 Y1 - 2004 SN - 0021-9290 SP - 1802 ER - TY - JOUR A1 - Sponagel, Stefan A1 - Baroud, Gamal A1 - Steffen, T. A1 - Wu, J. T1 - Parameter identification for cement infiltration of osteoporotic bone JF - Poromechanics II : Proceedings of the Second Biot Conference on Poromechanics Grenoble, France 26 - 28 August 2002 / ed. by J.-L. Auriault ... Y1 - 2002 SN - 90-5809-394-8 SP - 55 EP - 58 PB - Balkema CY - Lisse [u.a.] ER - TY - JOUR A1 - Scholz, A. A1 - Ley, Wilfried A1 - Dachwald, Bernd A1 - Miau, J. J. A1 - Juang, J. C. T1 - Flight results of the COMPASS-1 picosatellite mission JF - Acta Astronautica N2 - The mission of the COMPASS-1 picosatellite is to take pictures of the earth, to validate a space-borne GPS receiver developed by the German Aerospace Center, and to verify the proper operation of the magnetic attitude control system in orbit. The spacecraft was launched on April 28, 2008 from the Indian space port Sriharikota, as part of the PSLV-C9 world record launch that simultaneously brought ten satellites into orbit. The mission operations were carried out from the ground stations in Aachen and Tainan. Arising difficulties in the communication link were overcome with the support of individuals from the amateur radio community. After several months of mission operation, abundant housekeeping and mission data has been commanded, received and analyzed and is presented in this paper. Y1 - 2010 U6 - https://doi.org/10.1016/j.actaastro.2010.06.040 SN - 0094-5765 VL - 76 IS - 9-10 SP - 1289 EP - 1298 PB - Elsevier CY - Amsterdam ER -