TY - JOUR A1 - Dachwald, Bernd A1 - Wurm, Patrick T1 - Mission analysis and performance comparison for an Advanced Solar Photon Thruster JF - Advances in Space Research Y1 - 2011 SN - 0273-1177 VL - 48 IS - 11 SP - 1858 EP - 1868 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Dachwald, Bernd A1 - Tsinas, L. T1 - A combined neural and genetic learning algorithm / Tsinas, L. ; Dachwald, B. JF - Proceedings of the First IEEE Conference on Evolutionary Computation, 1994. IEEE World Congress on Computational Intelligence. Y1 - 1994 SN - 0-7803-1899-4 SP - 770 EP - 774 CY - Orlando, Fl ER - TY - JOUR A1 - Baader, Fabian A1 - Boxberg, Marc S. A1 - Chen, Qian A1 - Förstner, Roger A1 - Kowalski, Julia A1 - Dachwald, Bernd T1 - Field-test performance of an ice-melting probe in a terrestrial analogue environment JF - Icarus N2 - Melting probes are a proven tool for the exploration of thick ice layers and clean sampling of subglacial water on Earth. Their compact size and ease of operation also make them a key technology for the future exploration of icy moons in our Solar System, most prominently Europa and Enceladus. For both mission planning and hardware engineering, metrics such as efficiency and expected performance in terms of achievable speed, power requirements, and necessary heating power have to be known. Theoretical studies aim at describing thermal losses on the one hand, while laboratory experiments and field tests allow an empirical investigation of the true performance on the other hand. To investigate the practical value of a performance model for the operational performance in extraterrestrial environments, we first contrast measured data from terrestrial field tests on temperate and polythermal glaciers with results from basic heat loss models and a melt trajectory model. For this purpose, we propose conventions for the determination of two different efficiencies that can be applied to both measured data and models. One definition of efficiency is related to the melting head only, while the other definition considers the melting probe as a whole. We also present methods to combine several sources of heat loss for probes with a circular cross-section, and to translate the geometry of probes with a non-circular cross-section to analyse them in the same way. The models were selected in a way that minimizes the need to make assumptions about unknown parameters of the probe or the ice environment. The results indicate that currently used models do not yet reliably reproduce the performance of a probe under realistic conditions. Melting velocities and efficiencies are constantly overestimated by 15 to 50 % in the models, but qualitatively agree with the field test data. Hence, losses are observed, that are not yet covered and quantified by the available loss models. We find that the deviation increases with decreasing ice temperature. We suspect that this mismatch is mainly due to the too restrictive idealization of the probe model and the fact that the probe was not operated in an efficiency-optimized manner during the field tests. With respect to space mission engineering, we find that performance and efficiency models must be used with caution in unknown ice environments, as various ice parameters have a significant effect on the melting process. Some of these are difficult to estimate from afar. Y1 - 2023 U6 - https://doi.org/10.1016/j.icarus.2023.115852 N1 - Forschungsdaten hierzu: "Performance data of an ice-melting probe from field tests in two different ice environments" (https://opus.bibliothek.fh-aachen.de/opus4/frontdoor/index/index/docId/10890) IS - 409 PB - Elsevier CY - Amsterdam 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 - 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 - TY - JOUR A1 - Artmann, Gerhard A1 - Kelemen, Christina A1 - Porst, Dariusz A1 - Büldt, G. [u.a.] T1 - Temperature transitions of protein properties in human red blood cells. Artmann, Gerhard Michael, Kelemen, Christina; Porst, D.; Büldt, G.; Chien, S. JF - Biophysical Journal. 75 (1998), H. 6 Y1 - 1998 SN - 1542-0086 N1 - http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=1299989&blobtype=pdf SP - 3179 EP - 3183 ER - TY - JOUR A1 - Artmann, Gerhard A1 - Shi, Young de A1 - Agosti, R. A1 - Longhini, E. T1 - A modified casson equation to characterize blood rheology for hypertension. Shi, Young de; Artmann, Gerhard Michael; Agosti, R.; Longhini, E. JF - Clinical Hemorheology Microcirculation. 19 (1998), H. 2 Y1 - 1998 SN - 1386-0291 SP - 115 EP - 127 ER - TY - JOUR A1 - Li, Anlan A1 - Shi, Young de A1 - Landsmann, B. A1 - Schankowski-Bouvier, P. A1 - Dikta, Gerhard A1 - Bauer, U. A1 - Artmann, Gerhard T1 - Hemorheology and walking distance of Peripheral Arterial Occlusive Disease patients during treatment with Ginkgo-biloba extract JF - Acta Pharmacologica Sinica = ZHONGUO YAOLI XUEBAO. 19 (1998), H. 5 Y1 - 1998 SN - 1745-7254 N1 - ISSN der parallelen Ausgabe 1671-4083; China-Zs.-Code: CN31-1347 abstract frei unter SP - 417 EP - 421 ER - TY - JOUR A1 - Artmann, Gerhard A1 - Sung, K.-L. Paul A1 - Horn, Thomas A1 - Whittemore, Darren [u.a.] T1 - Micropipette aspiration of human erythrocytes induces echinocytes via membrane phospholipid translocation. Artmann, Gerhard Michael; Sung, K.-L. Paul; Horn, Thomas; Whittemore, Darren; Norwich, Gerald; Chien, Shu JF - Biophysical journal. 72 (1997), H. 3 Y1 - 1997 SN - 1542-0086 SP - 1434 EP - 1441 ER - TY - JOUR A1 - Artmann, Gerhard A1 - Trzewik, Jürgen A1 - Ates, M. T1 - A novel method to quantify mechanical tension in cell monolayers. Trzewik, Jürgen; Ates, M., Artmann, Gerhard Michael JF - Biomedizinische Technik. 47 (2002), H. Suppl. 1. Pt. 1 Y1 - 2002 SN - 0013-5585 N1 - Druckausgabe unter 63 Z 47 vorhanden SP - 379 EP - 381 ER - TY - JOUR A1 - Maggakis-Kelemen, Christina A1 - Biselli, Manfred A1 - Artmann, Gerhard T1 - Determination of the elastic shear modulus of cultured human red blood cells JF - Biomedizinische Technik. 47 (2002), H. Suppl. 1 Pt. 1 Y1 - 2002 SN - 0013-5585 N1 - Druckausgabe unter 63 Z 471 vorhanden SP - 106 EP - 109 ER - TY - JOUR A1 - Artmann, Gerhard A1 - Zhou-Stache, J. A1 - Buettner, R. A1 - Mittermayer, C. [u.a.] T1 - Inhibition of TNF-alpha induced cell death in HUVEC and Jurkat cells by protocatechuic acid. Zhou-Stache, J.; Buettner, R.; Artmann, Gerhard Michael; Mittermayer, C.; Bosserhoff, A. K. JF - Medical and Biological Engineering and Computing. 40 (2002), H. 6 Y1 - 2002 SN - 0140-0118 SP - 698 EP - 703 ER - TY - JOUR A1 - Artmann, Gerhard A1 - Trzewik, Jürgen A1 - Mallipattu, S. K. A1 - Delano, F. A. [u.a.] T1 - Evidence for a second valve system in Lymphatics: Endothelial Microvalves. Trzewik, Jürgen; Mallipattu, S. K.; Artmann, Gerhard Michael; Delano, F. A.; Schmid-Schonbein, G. W JF - The FASEB Journal. 15 (2001) Y1 - 2001 SN - 1530-6860 SP - 1711 EP - 1717 ER - TY - JOUR A1 - Artmann, Gerhard A1 - Bäumler, H. A1 - Voigt, A. A1 - Mitlöhner, R. [u.a.] T1 - Plastic behaviour of polyelectrolyte microcapsules derived from colloid templates. Bäumler, H., Artmann, Gerhard Michael; Voigt, A., Mitlöhner, R., Neu, B., Kiesewetter, H. JF - Journal of Microencapsulation. 17 (2000), H. 5 Y1 - 2000 SN - 1464-5246 SP - 651 EP - 655 ER - TY - JOUR A1 - Artmann, Gerhard A1 - Gorbatenkova, E. A. A1 - Panasenko, O. M. T1 - Hypochlorous acid and human blood low density lipoproteins modified by hypochlorous acid increase erythrocyte adhesion to endothelial cells. Gorbatenkova, E. A.; Artmann, Gerhard Michael; Panasenko, O. M. JF - Membrane and cell biology. 13 (2000), H. 4 Y1 - 2000 SN - 1023-6597 SP - 537 EP - 546 ER - TY - JOUR A1 - Artmann, Gerhard A1 - Kelemen, C. A1 - Chien, S. T1 - Temperature transition of human hemoglobin at body temperature: effects of calcium. Kelemen, C.; Chien, S.; Artmann, Gerhard Michael JF - Biophysical journal. 80 (2001), H. 6 Y1 - 2001 SN - 1542-0086 SP - 2622 EP - 2630 ER - TY - JOUR A1 - Artmann, Gerhard A1 - Hueck, I. S. A1 - Hollweg, H. G. A1 - Schmid-Schönbein, G. W. T1 - Chlorpromazine modulates the Morphological Macro- and Microstructure of Endothelial Cells. Hueck, I. S.; Hollweg, H. G.; Schmid-Schönbein, G. W.; Artmann, Gerhard Michael JF - American Journal of Physiology. Cell Physiology. 278 (2000), H. 5 Y1 - 2000 SN - 1522-1563 N1 - Zählung: C873- C878 SP - 873 EP - 878 ER - TY - JOUR A1 - Artmann, Gerhard A1 - Li, Anlan A1 - Seipelt, H. A1 - Müller, C. [u.a.] T1 - Effects of salicylic acid derivatives on red blood cell membranes. Li, Anlan; Seipelt, H.; Müller, C.;Shi, Yong de; Artmann, Gerhard Michael JF - Pharmacology and Toxicology. 85 (1999) Y1 - 1999 SN - 0902-9938 SP - 206 EP - 211 ER - TY - JOUR A1 - Artmann, Gerhard A1 - Hovav, T. A1 - Goldfarb, A. A1 - Yedgar, S. [u.a.] T1 - Enhanced adherence of beta-thalassaemic erythrocytes to endothelial cells. Hovav, T., Goldfarb, A.; Artmann, Gerhard Michael, Yedgar, S.; Barstein, G. JF - British Journal of Haematology. 106 (1999), H. 1 Y1 - 1999 SN - 1365-2141 SP - 178 EP - 181 ER - TY - JOUR A1 - Artmann, Gerhard T1 - A microscopic photometric method for measuring erythrocyte deformability. Artmann, Gerhard Michael JF - Clinical Hemorheology. 6 (1986) Y1 - 1986 SN - 0271-5198 SP - 617 EP - 627 ER -