TY - JOUR A1 - Christen, Marc A1 - Kowalski, Julia A1 - Bartelt, Perry T1 - RAMMS: Numerical simulation of dense snow avalanches in three-dimensional terrain JF - Cold Regions Science and Technology N2 - Numerical avalanche dynamics models have become an essential part of snow engineering. Coupled with field observations and historical records, they are especially helpful in understanding avalanche flow in complex terrain. However, their application poses several new challenges to avalanche engineers. A detailed understanding of the avalanche phenomena is required to construct hazard scenarios which involve the careful specification of initial conditions (release zone location and dimensions) and definition of appropriate friction parameters. The interpretation of simulation results requires an understanding of the numerical solution schemes and easy to use visualization tools. We discuss these problems by presenting the computer model RAMMS, which was specially designed by the SLF as a practical tool for avalanche engineers. RAMMS solves the depth-averaged equations governing avalanche flow with accurate second-order numerical solution schemes. The model allows the specification of multiple release zones in three-dimensional terrain. Snow cover entrainment is considered. Furthermore, two different flow rheologies can be applied: the standard Voellmy–Salm (VS) approach or a random kinetic energy (RKE) model, which accounts for the random motion and inelastic interaction between snow granules. We present the governing differential equations, highlight some of the input and output features of RAMMS and then apply the models with entrainment to simulate two well-documented avalanche events recorded at the Vallée de la Sionne test site. KW - RAMMS KW - snow KW - avalanche Y1 - 2010 U6 - http://dx.doi.org/10.1016/j.coldregions.2010.04.005 SN - 1872-7441 VL - 63 IS - 1-2 SP - 1 EP - 14 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Christiaens, P. A1 - Abouzar, Maryam H. A1 - Poghossian, Arshak A1 - Wagner, Torsten A1 - Bijnens, N. A1 - Williams, O. A. A1 - Daenen, M. A1 - Haenen, K. A1 - Douthéret, O. A1 - Haen, J. d´ A1 - Mekhalif, Z. A1 - Schöning, Michael Josef A1 - Wagner, P. T1 - pH sensitivity of nanocrystalline diamond films JF - Physica status solidi (A). 204 (2007), H. 9 Y1 - 2007 SN - 0031-8965 SP - 2925 EP - 2930 ER - TY - JOUR A1 - Christiaens, P. A1 - Abouzar, Maryam H. A1 - Poghossian, Arshak A1 - Wagner, Torsten A1 - Bijnens, N. A1 - Williams, O. A. A1 - Daenen, M. A1 - Haenen, K. A1 - Schöning, Michael Josef A1 - Wagner, P. T1 - Nanocrystalline diamond-based field-effect capacitive pH sensor JF - Transducers '07 Eurosensors XXI : digest of technical papers ; the14th International Conference on Solid-State Sensors, Actuators and Microsystems, June 10-14, 2007, Lyon, France / Gilles Delapierre (Ed.) Y1 - 2007 SN - 1-4244-0841-5 N1 - Eurosensors 21, 2007, Lyon ; International Conference on Solid-State Sensors, Actuators and Microsystems 14, 2007, Lyon SP - 1891 EP - 1894 PB - IEEE CY - Piscataway ER - TY - CHAP A1 - Christian, Esser A1 - Montag, Tim A1 - Schuba, Marko A1 - Allhof, Manuel T1 - Future critical infrastructure and security - cyberattacks on charging stations T2 - 31st International Electric Vehicle Symposium & Exhibition and International Electric Vehicle Technology Conference (EVS31 & EVTeC 2018) Y1 - 2018 SN - 978-1-5108-9157-9 SP - 665 EP - 671 PB - Society of Automotive Engineers of Japan (JSAE) CY - Tokyo ER - TY - JOUR A1 - Christoph, Thomas A1 - Bahrenberg, Gregor A1 - Vry, Jean de A1 - Englberger, Werner A1 - Erdmann, Volker A. A1 - Frech, Moritz A1 - Kögel, Babette A1 - Röhl, Thomas A1 - Schiene, Klaus A1 - Schröder, Wolfgang A1 - Seibler, Jost A1 - Kurreck, Jens T1 - Investigation of TRPV1 loss-of-function phenotypes in transgenic shRNA expressing and knockout mice JF - Molecular and Cellular Neuroscience Y1 - 2008 U6 - http://dx.doi.org/10.1016/j.mcn.2007.12.006 SN - 1044-7431 VL - 37 IS - 3 SP - 579 EP - 589 ER - TY - CHAP A1 - Chudoba, Rostislav A1 - Butenweg, Christoph A1 - Kuhlmann, Wolfram T1 - Technical information system for collaborative material research T2 - Sixth International Conference on Computational Structures Technology : [Prague, Czech Republic, 4 - 6 September 2002] Y1 - 2002 SP - 1 EP - 11 ER - TY - JOUR A1 - Chudoba, Rostislav A1 - Butenweg, Christoph A1 - Peiffer, F. T1 - Technical information system for collaborative material research JF - Advances in engineering software Y1 - 2004 U6 - http://dx.doi.org/10.1016/j.advengsoft.2004.03.021 SN - 1873-5339 (E-Journal); 0965-9978 (Print) VL - Volume 35 IS - Issue 10-11 SP - 747 EP - 756 ER - TY - CHAP A1 - Chudoba, Rostislav A1 - Butenweg, Christoph A1 - Pfeiffer, Frank T1 - Textile reinforced concrete. Part I: Process model for collaborative research and development T2 - Digital proceedings / IKM 2003, proceedings 16th International Conference on the Applications of Computer Science and Mathematics in Architecture and Civil Engineering [Elektronische Ressource : 10. - 12. Juni 2003, Weimar] / Bauhaus-Universität Weimar. Ed.: K. Gürlebeck; L. Hempel; C. Könke Y1 - 2003 SP - 1 EP - 8 PB - IKM CY - Weimar ER - TY - CHAP A1 - Chudoba, Rostislav A1 - Konrad, Martin A1 - Schleser, Markus A1 - Meskouris, Konstantin A1 - Reisgen, Uwe ED - Curbach, Manfred T1 - Parametric study of tensile response of TRC specimens reinforced with epoxy-penetrated multi-filament yarns T2 - Textilbeton - Theorie und Praxis : Tagungsband zum 4. Kolloquium zu textilbewehrten Tragwerken (CTRS4) und zur 1. Anwendertagung, Dresden, 3.6.2009 - 5.6.2009 Y1 - 2009 SN - 978-3-86780-122-5 SP - 87 EP - 98 PB - Techn. Univ. CY - Dresden ER - TY - CHAP A1 - Churilov, Sergej A1 - Dumova-Jovanoska, Elena A1 - Butenweg, Christoph ED - Adam, Christoph ED - Heuer, Rudolf ED - Lenhardt, Wolfgang ED - Schranz, Christian T1 - Seismic verification of existing masonry buildings and strengthening with reinforced concrete jackets T2 - Proceedings - Vienna Congress on Recent Advances in Earthquake Engineering and Structural Dynamics 2013 (VEESD 2013) N2 - A methodology for assessment, seismic verification and strengthening of existing masonry buildings is presented in this paper. The verification is performed using a calculation model calibrated with the results from ambient vibration measurements. The calibrated model serves as an input for a deformation-based verification procedure based on the Capacity Spectrum Method (CSM). The bearing capacity of the building is calculated from experimental capacity curves of the individual walls idealized with bilinear elastic-perfectly plastic curves. The experimental capacity curves were obtained from in-plane cyclic loading tests on unreinforced and strengthened masonry walls with reinforced concrete jackets. The seismic action is compared with the load-bearing capacity of the building considering non-linear material behavior with its post-peak capacity. The application of the CSM to masonry buildings and the influence of a traditional strengthening method are demonstrated on the example of a public school building in Skopje, Macedonia. Y1 - 2013 SN - 978-3-902749-04-8 N1 - Vienna Congress on Recent Advances in Earthquake Engineering and Structural Dynamics, Vienna, Austria, Paper No. 523 13. D-A-CH Tagung ; Vienna, Austria, 29. - 30. August 2013 http://hdl.handle.net/20.500.12188/15830 (Error - Cannot Connect to Server) ER - TY - BOOK A1 - Chwallek, Constanze A1 - Felden, Birgit T1 - RatingCheck : Wertschöpfungskette / Chwallek, Constanze ; Felden, Birgit Y1 - 2006 PB - Deutscher Sparkassen Verlag CY - Stuttgart ER - TY - JOUR A1 - Ciobanu, Octavian A1 - Staat, Manfred A1 - Rahimi, Alireza T1 - The use of open source software in biomechanical finite element analysis JF - Buletinul Institutului Politehnic din Iaşi / Universitatea Tehnică Gh. Asachi, Iaşi Secţia 5, Construcţii de maşini = Machine construction = Bulletin of the Polytechnic Institute of Jassy = Izvestija Jasskogo Politechničeskogo Instituta Y1 - 2008 SN - 1011-2855 VL - 54 IS - 7/8 SP - 213 EP - 220 ER - TY - JOUR A1 - Ciritsis, Alexander A1 - Horbach, Andreas A1 - Staat, Manfred A1 - Kuhl, Christiane K. A1 - Kraemer, Nils Andreas T1 - Porosity and tissue integration of elastic mesh implants evaluated in vitro and in vivo JF - Journal of Biomedical Materials Research: Part B: Applied Biomaterials N2 - Purpose In vivo, a loss of mesh porosity triggers scar tissue formation and restricts functionality. The purpose of this study was to evaluate the properties and configuration changes as mesh deformation and mesh shrinkage of a soft mesh implant compared with a conventional stiff mesh implant in vitro and in a porcine model. Material and Methods Tensile tests and digital image correlation were used to determine the textile porosity for both mesh types in vitro. A group of three pigs each were treated with magnetic resonance imaging (MRI) visible conventional stiff polyvinylidene fluoride meshes (PVDF) or with soft thermoplastic polyurethane meshes (TPU) (FEG Textiltechnik mbH, Aachen, Germany), respectively. MRI was performed with a pneumoperitoneum at a pressure of 0 and 15 mmHg, which resulted in bulging of the abdomen. The mesh-induced signal voids were semiautomatically segmented and the mesh areas were determined. With the deformations assessed in both mesh types at both pressure conditions, the porosity change of the meshes after 8 weeks of ingrowth was calculated as an indicator of preserved elastic properties. The explanted specimens were examined histologically for the maturity of the scar (collagen I/III ratio). Results In TPU, the in vitro porosity increased constantly, in PVDF, a loss of porosity was observed under mild stresses. In vivo, the mean mesh areas of TPU were 206.8 cm2 (± 5.7 cm2) at 0 mmHg pneumoperitoneum and 274.6 cm2 (± 5.2 cm2) at 15 mmHg; for PVDF the mean areas were 205.5 cm2 (± 8.8 cm2) and 221.5 cm2 (± 11.8 cm2), respectively. The pneumoperitoneum-induced pressure increase resulted in a calculated porosity increase of 8.4% for TPU and of 1.2% for PVDF. The mean collagen I/III ratio was 8.7 (± 0.5) for TPU and 4.7 (± 0.7) for PVDF. Conclusion The elastic properties of TPU mesh implants result in improved tissue integration compared to conventional PVDF meshes, and they adapt more efficiently to the abdominal wall. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 827–833, 2018. Y1 - 2018 U6 - http://dx.doi.org/10.1002/jbm.b.33877 SN - 1552-4981 VL - 106 IS - 2 SP - 827 EP - 833 PB - Wiley CY - New York, NY ER - TY - JOUR A1 - Claer, Mario A1 - Ferrein, Alexander A1 - Schiffer, Stefan T1 - Calibration of a Rotating or Revolving Platform with a LiDAR Sensor JF - Applied Sciences Y1 - 2019 U6 - http://dx.doi.org/10.3390/app9112238 SN - 2076-3417 VL - Volume 9 IS - issue 11, 2238 PB - MDPI CY - Basel ER - TY - JOUR A1 - Claessens, J. A1 - Fuchsberger, A. A1 - Günther, C. A1 - Horn, G. A1 - Howker, K. A1 - Hulsebosch, R.J. A1 - Mitchell, C. A1 - Paterson, K. A1 - Preneel, B. A1 - Schellekens, D. A1 - Schuba, Marko T1 - Pioneering Advanced Mobile Privacy and Security Y1 - 2003 N1 - electronic proceedings of the 18th IFIP International Information Security Conference, Athens, Greece, May 2003 SP - 1 EP - 17 ER - TY - JOUR A1 - Coll-Perales, Baldomero A1 - Schulte-Tigges, Joschua A1 - Rondinone, Michele A1 - Gozalvez, Javier A1 - Reke, Michael A1 - Matheis, Dominik A1 - Walter, Thomas T1 - Prototyping and evaluation of infrastructure-assisted transition of control for cooperative automated vehicles JF - IEEE Transactions on Intelligent Transportation Systems N2 - Automated driving is now possible in diverse road and traffic conditions. However, there are still situations that automated vehicles cannot handle safely and efficiently. In this case, a Transition of Control (ToC) is necessary so that the driver takes control of the driving. Executing a ToC requires the driver to get full situation awareness of the driving environment. If the driver fails to get back the control in a limited time, a Minimum Risk Maneuver (MRM) is executed to bring the vehicle into a safe state (e.g., decelerating to full stop). The execution of ToCs requires some time and can cause traffic disruption and safety risks that increase if several vehicles execute ToCs/MRMs at similar times and in the same area. This study proposes to use novel C-ITS traffic management measures where the infrastructure exploits V2X communications to assist Connected and Automated Vehicles (CAVs) in the execution of ToCs. The infrastructure can suggest a spatial distribution of ToCs, and inform vehicles of the locations where they could execute a safe stop in case of MRM. This paper reports the first field operational tests that validate the feasibility and quantify the benefits of the proposed infrastructure-assisted ToC and MRM management. The paper also presents the CAV and roadside infrastructure prototypes implemented and used in the trials. The conducted field trials demonstrate that infrastructure-assisted traffic management solutions can reduce safety risks and traffic disruptions. KW - Automated driving KW - automated vehicles KW - connected automated vehicles KW - CAV KW - experimental evaluation Y1 - 2021 U6 - http://dx.doi.org/10.1109/TITS.2021.3061085 SN - 1524-9050 (Print) SN - 1558-0016 (Online) VL - 23 IS - 7 SP - 6720 EP - 6736 PB - IEEE ER - TY - JOUR A1 - Colombo, Daniele A1 - Drira, Slah A1 - Frotscher, Ralf A1 - Staat, Manfred T1 - An element-based formulation for ES-FEM and FS-FEM models for implementation in standard solid mechanics finite element codes for 2D and 3D static analysis JF - International Journal for Numerical Methods in Engineering N2 - Edge-based and face-based smoothed finite element methods (ES-FEM and FS-FEM, respectively) are modified versions of the finite element method allowing to achieve more accurate results and to reduce sensitivity to mesh distortion, at least for linear elements. These properties make the two methods very attractive. However, their implementation in a standard finite element code is nontrivial because it requires heavy and extensive modifications to the code architecture. In this article, we present an element-based formulation of ES-FEM and FS-FEM methods allowing to implement the two methods in a standard finite element code with no modifications to its architecture. Moreover, the element-based formulation permits to easily manage any type of element, especially in 3D models where, to the best of the authors' knowledge, only tetrahedral elements are used in FS-FEM applications found in the literature. Shape functions for non-simplex 3D elements are proposed in order to apply FS-FEM to any standard finite element. KW - distorted element KW - ES-FEM KW - FS-FEM KW - non-simplex S-FEM elements KW - S-FEM Y1 - 2022 U6 - http://dx.doi.org/10.1002/nme.7126 SN - 1097-0207 VL - 124 IS - 2 SP - 402 EP - 433 PB - Wiley CY - Chichester ER - TY - RPRT A1 - Conan, Yulian A1 - D'Haeyer, R. A1 - Béguin, P. A1 - Döring, Bernd A1 - Kuhnhenne, Markus A1 - Bayo, E. T1 - Steel in low-rise building : a symbiosis of cold formed sections and light rolled profiles : final report. Contract-No. 7215-PP/070. EUR 22080 en Y1 - 2006 SN - 92-79-02082-X PB - Office for Official Publications of the European Communities CY - Luxembourg ER - TY - JOUR A1 - Conzen, Catharina A1 - Albanna, Walid A1 - Weiss, Miriam A1 - Kürten, David A1 - Vilser, Walthard A1 - Kotliar, Konstantin A1 - Zäske, Charlotte A1 - Clusmann, Hans A1 - Schubert, Gerrit Alexander T1 - Vasoconstriction and Impairment of Neurovascular Coupling after Subarachnoid Hemorrhage: a Descriptive Analysis of Retinal Changes JF - Translational Stroke Research N2 - Impaired cerebral autoregulation and neurovascular coupling (NVC) contribute to delayed cerebral ischemia after subarachnoid hemorrhage (SAH). Retinal vessel analysis (RVA) allows non-invasive assessment of vessel dimension and NVC hereby demonstrating a predictive value in the context of various neurovascular diseases. Using RVA as a translational approach, we aimed to assess the retinal vessels in patients with SAH. RVA was performed prospectively in 24 patients with acute SAH (group A: day 5–14), in 11 patients 3 months after ictus (group B: day 90 ± 35), and in 35 age-matched healthy controls (group C). Data was acquired using a Retinal Vessel Analyzer (Imedos Systems UG, Jena) for examination of retinal vessel dimension and NVC using flicker-light excitation. Diameter of retinal vessels—central retinal arteriolar and venular equivalent—was significantly reduced in the acute phase (p < 0.001) with gradual improvement in group B (p < 0.05). Arterial NVC of group A was significantly impaired with diminished dilatation (p < 0.001) and reduced area under the curve (p < 0.01) when compared to group C. Group B showed persistent prolonged latency of arterial dilation (p < 0.05). Venous NVC was significantly delayed after SAH compared to group C (A p < 0.001; B p < 0.05). To our knowledge, this is the first clinical study to document retinal vasoconstriction and impairment of NVC in patients with SAH. Using non-invasive RVA as a translational approach, characteristic patterns of compromise were detected for the arterial and venous compartment of the neurovascular unit in a time-dependent fashion. Recruitment will continue to facilitate a correlation analysis with clinical course and outcome. Y1 - 2018 U6 - http://dx.doi.org/10.1007/s12975-017-0585-8 SN - 1868-601X IS - 9 SP - 284 EP - 293 PB - Springer Nature CY - Cham ER - TY - CHAP A1 - Cordes, Sven A1 - Gligorevic, Snjezana A1 - Blicharski, Peter T1 - Analysis of sine precision influence on DOA estimation using the MUSIC algorithm T2 - 2019 20th International Radar Symposium (IRS) Y1 - 2019 SN - 978-3-7369-9860-5 U6 - http://dx.doi.org/10.23919/IRS.2019.8768162 SP - 1 EP - 10 ER - TY - JOUR A1 - Cornelis, Peter A1 - Givanoudi, Stella A1 - Yongabi, Derick A1 - Iken, Heiko A1 - Duwé, Sam A1 - Deschaume, Olivier A1 - Robbens, Johan A1 - Dedecker, Peter A1 - Bartic, Carmen A1 - Wübbenhorst, Michael A1 - Schöning, Michael Josef A1 - Heyndrickx, Marc A1 - Wagner, Patrick T1 - Sensitive and specific detection of E. coli using biomimetic receptors in combination with a modified heat-transfer method JF - Biosensors and Bioelectronics Y1 - 2019 U6 - http://dx.doi.org/10.1016/j.bios.2019.04.026 SN - 0956-5663 VL - 136 SP - 97 EP - 105 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Cosma, Cosmin A1 - Kessler, Julia A1 - Gebhardt, Andreas A1 - Campbell, Ian A1 - Balc, Nicolae T1 - Improving the Mechanical Strength of Dental Applications and Lattice Structures SLM Processed JF - Materials N2 - To manufacture custom medical parts or scaffolds with reduced defects and high mechanical characteristics, new research on optimizing the selective laser melting (SLM) parameters are needed. In this work, a biocompatible powder, 316L stainless steel, is characterized to understand the particle size, distribution, shape and flowability. Examination revealed that the 316L particles are smooth, nearly spherical, their mean diameter is 39.09 μm and just 10% of them hold a diameter less than 21.18 μm. SLM parameters under consideration include laser power up to 200 W, 250–1500 mm/s scanning speed, 80 μm hatch spacing, 35 μm layer thickness and a preheated platform. The effect of these on processability is evaluated. More than 100 samples are SLM-manufactured with different process parameters. The tensile results show that is possible to raise the ultimate tensile strength up to 840 MPa, adapting the SLM parameters for a stable processability, avoiding the technological defects caused by residual stress. Correlating with other recent studies on SLM technology, the tensile strength is 20% improved. To validate the SLM parameters and conditions established, complex bioengineering applications such as dental bridges and macro-porous grafts are SLM-processed, demonstrating the potential to manufacture medical products with increased mechanical resistance made of 316L. Y1 - 2020 U6 - http://dx.doi.org/10.3390/ma13040905 SN - 1996-1944 VL - 13 IS - 4 SP - 1 EP - 18 PB - MDPI CY - Basel ER - TY - CHAP A1 - Cresser, J. D. A1 - Häger, J. A1 - Leuchs, G. A1 - Rateike, Franz-Matthias A1 - Walther, H. T1 - Resonance fluorescence of atoms in strong monochromatic laser fields T2 - Dissipative systems in quantum optics. Ed. by Rodolfo Bonifacio. Topics in current physics. Vol. 27 N2 - The investigation of atomic resonance fluorescence has always been of special interest as a means for the determination of atomic parameters. In addition, information on the interaction mechanism between atoms and radiation can be obtained. In the standard fluorescence experiment the frequency distribution of the incident photons is larger than the natural width of the respective transition; as a consequence the correlation time in the photon-atom interaction is determined by the lifetime of the atoms in the excited state. With the development of lasers and especially of tunable dye lasers in recent years it became possible to study the case where the incident radiation has a spectral distribution which is narrower than the natural width. This corresponds to a correlation time of the incoming light wave which is much longer than the excited-state lifetime. In this chapter a survey of experiments on the resonance fluorescence of atoms in monochromatic laser fields will be given. Y1 - 1982 SN - 978-3-642-81719-9 U6 - http://dx.doi.org/10.1007/978-3-642-81717-5_3 SP - 21 EP - 59 PB - Springer CY - Berlin ER - TY - CHAP A1 - Croon, Philipp A1 - Czarnecki, Christian ED - Czarnecki, Christian ED - Fettke, Peter T1 - Liability for loss or damages caused by RPA T2 - Robotic process automation : Management, technology, applications N2 - Intelligent autonomous software robots replacing human activities and performing administrative processes are reality in today’s corporate world. This includes, for example, decisions about invoice payments, identification of customers for a marketing campaign, and answering customer complaints. What happens if such a software robot causes a damage? Due to the complete absence of human activities, the question is not trivial. It could even happen that no one is liable for a damage towards a third party, which could create an uncalculatable legal risk for business partners. Furthermore, the implementation and operation of those software robots involves various stakeholders, which result in the unsolvable endeavor of identifying the originator of a damage. Overall it is advisable to all involved parties to carefully consider the legal situation. This chapter discusses the liability of software robots from an interdisciplinary perspective. Based on different technical scenarios the legal aspects of liability are discussed. KW - robotic process automation KW - artificial intelligence KW - liability KW - culpability Y1 - 2021 SN - 9783110676778 SN - 9783110676693 SN - 9783110676686 U6 - http://dx.doi.org/10.1515/9783110676693-202 SP - 135 EP - 151 PB - De Gruyter CY - Oldenbourg ER - TY - CHAP A1 - Czarnecki, Christian ED - vom Brocke, Jan ED - Mendling, Jan T1 - Establishment of a central process governance organization combined with operational process improvements : Insights from a BPM Project at a leading telecommunications operator in the Middle East T2 - Business process management cases : digital innovation and business transformation in practice N2 - Because of customer churn, strong competition, and operational inefficiencies, the telecommunications operator ME Telco (fictitious name due to confidentiality) launched a strategic transformation program that included a Business Process Management (BPM) project. Major problems were silo-oriented process management and missing cross-functional transparency. Process improvements were not consistently planned and aligned with corporate targets. Measurable inefficiencies were observed on an operational level, e.g., high lead times and reassignment rates of the incident management process. Y1 - 2018 SN - 978-3-319-58306-8 SN - 978-3-319-58307-5 SN - 978-3-319-86372-6 U6 - http://dx.doi.org/10.1007/978-3-319-58307-5 N1 - Als Präsenzexemplar unter der Signatur 20 PZR 469-1 vorhanden. SP - 57 EP - 76 PB - Springer CY - Cham ER - TY - CHAP A1 - Czarnecki, Christian A1 - Dietze, Christian ED - Maedche, Alexander ED - vom Brocke, Jan ED - Hevner, Alan T1 - Domain-Specific reference modeling in the telecommunications industry T2 - DESRIST 2017: Designing the Digital Transformation N2 - The telecommunications industry is currently going through a major transformation. In this context, the enhanced Telecom Operations Map (eTOM) is a domain-specific process reference model that is offered by the industry organization TM Forum. In practice, eTOM is well accepted and confirmed as de facto standard. It provides process definitions and process flows on different levels of detail. This article discusses the reference modeling of eTOM, i.e., the design, the resulting artifact, and its evaluation based on three project cases. The application of eTOM in three projects illustrates the design approach and concrete models on strategic and operational levels. The article follows the Design Science Research (DSR) paradigm. It contributes with concrete design artifacts to the transformational needs of the telecommunications industry and offers lessons-learned from a general DSR perspective. KW - enhanced Telecom Operations Map (eTOM) KW - Process reference model KW - Process design KW - Map (eTOM) Process reference model Process design Telecommunications industry Y1 - 2017 SN - 978-3-319-59144-5 SN - 978-3-319-59143-8 U6 - http://dx.doi.org/10.1007/978-3-319-59144-5_19 N1 - Designing the Digital Transformation 12th International Conference, DESRIST 2017, Karlsruhe, Germany, May 30 - June 1, 2017. SP - 313 EP - 329 PB - Springer CY - Cham ER - TY - BOOK A1 - Czarnecki, Christian A1 - Dietze, Christian T1 - Reference architecture for the telecommunications industry: Transformation of strategy, organization, processes, data, and applications N2 - This book reflects the tremendous changes in the telecommunications industry in the course of the past few decades – shorter innovation cycles, stiffer competition and new communication products. It analyzes the transformation of processes, applications and network technologies that are now expected to take place under enormous time pressure. The International Telecommunication Union (ITU) and the TM Forum have provided reference solutions that are broadly recognized and used throughout the value chain of the telecommunications industry, and which can be considered the de facto standard. The book describes how these reference solutions can be used in a practical context: it presents the latest insights into their development, highlights lessons learned from numerous international projects and combines them with well-founded research results in enterprise architecture management and reference modeling. The complete architectural transformation is explained, from the planning and set-up stage to the implementation. Featuring a wealth of examples and illustrations, the book offers a valuable resource for telecommunication professionals, enterprise architects and project managers alike. KW - Enterprise architecture KW - Enterprise transformation KW - Reference modelling KW - TM Forum KW - Telecommunication Y1 - 2017 SN - 978-3-319-46755-9 (Print) SN - 978-3-319-83578-5 (Print) SN - 978-3-319-46757-3 (PDF) U6 - http://dx.doi.org/10.1007/978-3-319-46757-3 PB - Springer CY - Cham ER - TY - CHAP A1 - Czarnecki, Christian A1 - Fettke, Peter ED - Czarnecki, Christian ED - Fettke, Peter T1 - Robotic process automation : Positioning, structuring, and framing the work T2 - Robotic process automation : Management, technology, applications N2 - Robotic process automation (RPA) has attracted increasing attention in research and practice. This chapter positions, structures, and frames the topic as an introduction to this book. RPA is understood as a broad concept that comprises a variety of concrete solutions. From a management perspective RPA offers an innovative approach for realizing automation potentials, whereas from a technical perspective the implementation based on software products and the impact of artificial intelligence (AI) and machine learning (ML) are relevant. RPA is industry-independent and can be used, for example, in finance, telecommunications, and the public sector. With respect to RPA this chapter discusses definitions, related approaches, a structuring framework, a research framework, and an inside as well as outside architectural view. Furthermore, it provides an overview of the book combined with short summaries of each chapter. KW - Robotic process automation KW - management KW - technology KW - applications KW - research framework Y1 - 2021 SN - 978-3-11-067668-6 (Print) SN - 978-3-11-067669-3 (PDF) SN - 978-3-11-067677-8 (ePub) U6 - http://dx.doi.org/10.1515/9783110676693-202 SP - 3 EP - 24 PB - De Gruyter CY - Oldenbourg ER - TY - CHAP A1 - Czarnecki, Christian A1 - Heuser, Marcus A1 - Spiliopoulou, Myra ED - Irani, Zahir T1 - How does the implementation of a next generation network influence a telecommunication company? T2 - European and Mediterranean Conference on Information Systems N2 - As the potential of a Next Generation Network (NGN) is recognized, telecommunication companies consider switching to it. Although the implementation of an NGN seems to be merely a modification of the network infrastructure, it may trigger or require changes in the whole company and even influence the company strategy. To capture the effects of NGN we propose a framework based on concepts of business engineering and technical recommendations for the introduction of NGN technology. The specific design of solutions for the layers "Strategy", "Processes" and "Information Systems" as well as their interdependencies are an essential characteristic of the developed framework. We have per-formed a case study on NGN implementation and observed that all layers captured by our framework are influenced by the introduction of an NGN. KW - Next Generation Network KW - Business Engineering KW - Telecommunication Y1 - 2009 SN - 9781902316697 N1 - European and Mediterranean Conference on Information Systems 2009 (EMCIS2009), July 13-14, 2009, Crowne Plaza Hotel, Izmir SP - 1 EP - 11 PB - Brunel University CY - London ER - TY - CHAP A1 - Czarnecki, Christian A1 - Hong, Chin-Gi A1 - Schmitz, Manfred A1 - Dietze, Christian ED - Urbach, Nils ED - Röglinger, Maximilian ED - Kautz, Karlheinz ED - Alias, Rose Alinda ED - Saunders, Carol ED - Wiener, Martin T1 - Enabling digital transformation through cognitive robotic process automation at Deutsche Telekom Services Europe T2 - Digitalization Cases Vol. 2 : Mastering digital transformation for global business N2 - Subject of this case is Deutsche Telekom Services Europe (DTSE), a service center for administrative processes. Due to the high volume of repetitive tasks (e.g., 100k manual uploads of offer documents into SAP per year), automation was identified as an important strategic target with a high management attention and commitment. DTSE has to work with various backend application systems without any possibility to change those systems. Furthermore, the complexity of administrative processes differed. When it comes to the transfer of unstructured data (e.g., offer documents) to structured data (e.g., MS Excel files), further cognitive technologies were needed. Y1 - 2021 SN - 978-3-030-80002-4 (Print) SN - 978-3-030-80003-1 (Online) U6 - http://dx.doi.org/10.1007/978-3-030-80003-1 SP - 123 EP - 138 PB - Springer CY - Cham ER - TY - JOUR A1 - Czarnecki, Christian A1 - Spiliopoulou, Myra T1 - A holistic framework for the implementation of a next generation network JF - International Journal of Business Information Systems N2 - As the potential of a next generation network (NGN) is recognised, telecommunication companies consider switching to it. Although the implementation of an NGN seems to be merely a modification of the network infrastructure, it may trigger or require changes in the whole company, because it builds upon the separation between service and transport, a flexible bundling of services to products and the streamlining of the IT infrastructure. We propose a holistic framework, structured into the layers ‘strategy’, ‘processes’ and ‘information systems’ and incorporate into each layer all concepts necessary for the implementation of an NGN, as well as the alignment of these concepts. As a first proof-of-concept for our framework we have performed a case study on the introduction of NGN in a large telecommunication company; we show that our framework captures all topics that are affected by an NGN implementation. KW - next generation network KW - telecommunication KW - NGN KW - IP-based networks KW - product bundling Y1 - 2012 U6 - http://dx.doi.org/10.1504/IJBIS.2012.046291 SN - 1746-0972 VL - 9 IS - 4 SP - 385 EP - 401 PB - Inderscience Enterprises CY - Olney, Bucks ER - TY - CHAP A1 - Czarnecki, Christian A1 - Winkelmann, Axel A1 - Spiliopoulou, Myra ED - Pokorny, Jaroslav ED - Repa, Vaclav ED - Richta, Karel ED - Wojtkowski, Wita ED - Linger, Henry ED - Barry, Chris ED - Lang, Michael T1 - Making business systems in the telecommunication industry more customer-oriented T2 - Information Systems Development : Business Systems and Services: Modeling and Development N2 - Market changes have forced telecommunication companies to transform their business. Increased competition, short innovation cycles, changed usage patterns, increased customer expectations and cost reduction are the main drivers. Our objective is to analyze to what extend transformation projects have improved the orientation towards the end-customers. Therefore, we selected 38 real-life case studies that are dealing with customer orientation. Our analysis is based on a telecommunication-specific framework that aligns strategy, business processes and information systems. The result of our analysis shows the following: transformation projects that aim to improve the customer orientation are combined with clear goals on costs and revenue of the enterprise. These projects are usually directly linked to the customer touch points, but also to the development and provisioning of products. Furthermore, the analysis shows that customer orientation is not the sole trigger for transformation. There is no one-fits-all solution; rather, improved customer orientation needs aligned changes of business processes as well as information systems related to different parts of the company. KW - Business Process KW - Customer Orientation KW - Enterprise Architecture KW - Transformation Project KW - Telecommunication Industry Y1 - 2011 SN - 978-1-4419-9645-9 (Print) SN - 978-1-4419-9790-6 (Online) U6 - http://dx.doi.org/10.1007/978-1-4419-9790-6_14 N1 - 19th International Conference on Information Systems Development held in Prague, Czech Republic, August 25 - 27, 2010. SP - 169 EP - 180 PB - Springer CY - New York ER - TY - JOUR A1 - Czarnecki, Christian A1 - Winkelmann, Axel A1 - Spiliopoulou, Myra T1 - Services in electronic telecommunication markets: a framework for planning the virtualization of processes JF - Electronic Markets N2 - The potential of electronic markets in enabling innovative product bundles through flexible and sustainable partnerships is not yet fully exploited in the telecommunication industry. One reason is that bundling requires seamless de-assembling and re-assembling of business processes, whilst processes in telecommunication companies are often product-dependent and hard to virtualize. We propose a framework for the planning of the virtualization of processes, intended to assist the decision maker in prioritizing the processes to be virtualized: (a) we transfer the virtualization pre-requisites stated by the Process Virtualization Theory in the context of customer-oriented processes in the telecommunication industry and assess their importance in this context, (b) we derive IT-oriented requirements for the removal of virtualization barriers and highlight their demand on changes at different levels of the organization. We present a first evaluation of our approach in a case study and report on lessons learned and further steps to be performed. KW - Telecommunication KW - Services KW - Process virtualization KW - Product bundling KW - Transformation Y1 - 2010 U6 - http://dx.doi.org/10.1007/s12525-010-0045-8 SN - 1422-8890 VL - 20 IS - 3-4 SP - 197 EP - 207 PB - Springer CY - Berlin ER - TY - JOUR A1 - Czupalla, Markus A1 - Horneck, G. A1 - Blome, Hans-Joachim T1 - The conceptual design of a hybrid life support system based on the evaluation and comparison of terrestrial testbeds JF - Advances in Space Research Y1 - 2005 SN - 0273-1177 VL - 35 IS - 9 SP - 1609 EP - 1620 ER - TY - JOUR A1 - Dachwald, Bernd T1 - Optimization of very-low-thrust trajectories using evolutionary neurocontrol JF - Acta Astronautica. 57 (2005), H. 2-8 Y1 - 2005 SN - 0094-5765 SP - 175 EP - 185 ER - TY - JOUR A1 - Dachwald, Bernd T1 - Minimum Transfer Times for Nonperfectly Reflecting Solar Sailcraft JF - Journal of Spacecraft and Rockets. 41 (2004), H. 4 Y1 - 2004 SN - 0022-4650 N1 - 2. ISSN: 1533-6794 SP - 693 EP - 695 ER - TY - JOUR A1 - Dachwald, Bernd T1 - Optimal Solar Sail Trajectories for Missions to the Outer Solar System JF - Journal of guidance, control, and dynamics. 28 (2005), H. 6 Y1 - 2005 SN - 0162-3192 N1 - 2. ISSN: 0162-3192. - 3. ISSN: 0731-5090 SP - 1187 EP - 1193 ER - TY - JOUR A1 - Dachwald, Bernd T1 - Optimization of Interplanetary Solar Sailcraft Trajectories Using Evolutionary Neurocontrol JF - Journal of guidance, control, and dynamics. 27 (2004), H. 1 Y1 - 2004 SN - 0162-3192 N1 - 2. ISSN: 0162-3192. - 3. ISSN: 0731-5090 SP - 66 EP - 72 ER - TY - JOUR A1 - Dachwald, Bernd T1 - Interplanetary Mission Analysis for Non-Perfectly Reflecting Solar Sailcraft Using Evolutionary Neurocontrol JF - Astrodynamics 2003 : proceedings of the AAS/AIAA Astrodynamics Conference held August 3 - 7, 2003, Big Sky, Montana / ed. by Jean de Lafontaine. - Pt. 2. - (Advances in the astronautical sciences ; 116,2) Y1 - 2004 SN - 0-87703-509-1 N1 - Astrodynamics Conference <2003, Big Sky, Mont.> ; American Institute of Aeronautics and Astronautics ; AAS-03-579 SP - 1247 EP - 1262 PB - Univelt CY - San Diego, Calif. ER - TY - JOUR A1 - Dachwald, Bernd T1 - Low-Thrust Trajectory Optimization and Interplanetary Mission Analysis Using Evolutionary Neurocontrol JF - Deutscher Luft- und Raumfahrtkongress 2004 : Dresden, 20. bis 23. September 2004, Motto: Luft- und Raumfahrt - Brücke für eine wissensbasierte Gesellschaft / Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V. (DGLR). [Red.: Peter Brandt (verantwortlich)]. - Bd. 2. - (Jahrbuch ... der Deutschen Gesellschaft für Luft- und Raumfahrt) Y1 - 2004 N1 - Deutscher Luft- und Raumfahrt-Kongress <2004, Dresden> ; Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth ; DGLR-2004-116 SP - 917 EP - 926 CY - Bonn ER - TY - JOUR A1 - Dachwald, Bernd T1 - Evolutionary Neurocontrol: A Smart Method for Global Optimization of Low-Thrust Trajectories JF - 22nd AIAA Applied Aerodynamics Conference and Exhibit - AIAA/AAS Astrodynamics Specialist Conference and Exhibit - AIAA Guidance, Navigation, and Control Conference and Exhibit - AIAA Modeling and Simulation Technologies Conference and Exhibit - AIAA Atmospheric Flight Mechanics Conference and Exhibit : 16 - 19 August 2004, Providence, Rhode Island / American Institute of Aeronautics and Astronautics. - (AIAA meeting papers on disc ; 2004,14-15) Y1 - 2004 N1 - American Institute of Aeronautics and Astronautics ; AIAA/AAS Astrodynamics Specialist Conference and Exhibit <2004, Providence, RI> ; AIAA paper number: AIAA-2004-5405 PB - American Inst. of Aeronautics and Astronautics CY - Reston, Va. ER - TY - JOUR A1 - Dachwald, Bernd T1 - Optimal Solar Sail Trajectories for Missions to the Outer Solar System JF - 22nd AIAA Applied Aerodynamics Conference and Exhibit - AIAA/AAS Astrodynamics Specialist Conference and Exhibit - AIAA Guidance, Navigation, and Control Conference and Exhibit - AIAA Modeling and Simulation Technologies Conference and Exhibit - AIAA Atmospheric Flight Mechanics Conference and Exhibit : 16 - 19 August 2004, Providence, Rhode Island / American Institute of Aeronautics and Astronautics. - (AIAA meeting papers on disc ; 2004,14-15) Y1 - 2004 N1 - American Institute of Aeronautics and Astronautics ; AIAA/AAS Astrodynamics Specialist Conference and Exhibit <2004, Providence, RI> ; AIAA paper number: AIAA-2004-5406 PB - American Inst. of Aeronautics and Astronautics CY - Reston, Va. ER - TY - CHAP A1 - Dachwald, Bernd T1 - Low-Thrust Mission Analysis and Global Trajectory Optimization Using Evolutionary Neurocontrol: New Results T2 - European Workshop on Space Mission Analysis ESA/ESOC, Darmstadt, Germany 10 { 12 Dec 2007 N2 - Interplanetary trajectories for low-thrust spacecraft are often characterized by multiple revolutions around the sun. Unfortunately, the convergence of traditional trajectory optimizers that are based on numerical optimal control methods depends strongly on an adequate initial guess for the control function (if a direct method is used) or for the starting values of the adjoint vector (if an indirect method is used). Especially when many revolutions around the sun are re- quired, trajectory optimization becomes a very difficult and time-consuming task that involves a lot of experience and expert knowledge in astrodynamics and optimal control theory, because an adequate initial guess is extremely hard to find. Evolutionary neurocontrol (ENC) was proposed as a smart method for low-thrust trajectory optimization that fuses artificial neural networks and evolutionary algorithms to so-called evolutionary neurocontrollers (ENCs) [1]. Inspired by natural archetypes, ENC attacks the trajectoryoptimization problem from the perspective of artificial intelligence and machine learning, a perspective that is quite different from that of optimal control theory. Within the context of ENC, a trajectory is regarded as the result of a spacecraft steering strategy that maps permanently the actual spacecraft state and the actual target state onto the actual spacecraft control vector. This way, the problem of searching the optimal spacecraft trajectory is equivalent to the problem of searching (or "learning") the optimal spacecraft steering strategy. An artificial neural network is used to implement such a spacecraft steering strategy. It can be regarded as a parameterized function (the network function) that is defined by the internal network parameters. Therefore, each distinct set of network parameters defines a different network function and thus a different steering strategy. The problem of searching the optimal steering strategy is now equivalent to the problem of searching the optimal set of network parameters. Evolutionary algorithms that work on a population of (artificial) chromosomes are used to find the optimal network parameters, because the parameters can be easily mapped onto a chromosome. The trajectory optimization problem is solved when the optimal chromosome is found. A comparison of solar sail trajectories that have been published by others [2, 3, 4, 5] with ENC-trajectories has shown that ENCs can be successfully applied for near-globally optimal spacecraft control [1, 6] and that they are able to find trajectories that are closer to the (unknown) global optimum, because they explore the trajectory search space more exhaustively than a human expert can do. The obtained trajectories are fairly accurate with respect to the terminal constraint. If a more accurate trajectory is required, the ENC-solution can be used as an initial guess for a local trajectory optimization method. Using ENC, low-thrust trajectories can be optimized without an initial guess and without expert attendance. Here, new results for nuclear electric spacecraft and for solar sail spacecraft are presented and it will be shown that ENCs find very good trajectories even for very difficult problems. Trajectory optimization results are presented for 1. NASA's Solar Polar Imager Mission, a mission to attain a highly inclined close solar orbit with a solar sail [7] 2. a mission to de ect asteroid Apophis with a solar sail from a retrograde orbit with a very-high velocity impact [8, 9] 3. JPL's \2nd Global Trajectory Optimization Competition", a grand tour to visit four asteroids from different classes with a NEP spacecraft Y1 - 2007 ER - TY - CHAP A1 - Dachwald, Bernd T1 - Global optimization of low-thrust space missions using evolutionary neurocontrol T2 - Proceedings of the international workshop on global optimization N2 - Low-thrust space propulsion systems enable flexible high-energy deep space missions, but the design and optimization of the interplanetary transfer trajectory is usually difficult. It involves much experience and expert knowledge because the convergence behavior of traditional local trajectory optimization methods depends strongly on an adequate initial guess. Within this extended abstract, evolutionary neurocontrol, a method that fuses artificial neural networks and evolutionary algorithms, is proposed as a smart global method for low-thrust trajectory optimization. It does not require an initial guess. The implementation of evolutionary neurocontrol is detailed and its performance is shown for an exemplary mission. KW - Evolutionary Neurocontrol KW - Spacecraft Trajectory Optimization KW - Low-Thrust Propulsion Y1 - 2005 SP - 85 EP - 90 ER - TY - CHAP A1 - Dachwald, Bernd ED - Knopf, George K. ED - Otani, Yukitoshi T1 - Light propulsion systems for spacecraft T2 - Optical nano and micro actuator technology Y1 - 2017 SN - 9781315217628 (eBook) SP - 577 EP - 598 PB - CRC Press CY - Boca Raton ER - TY - CHAP A1 - Dachwald, Bernd T1 - Solar sail dynamics and control T2 - Encyclopedia of Aerospace Engineering N2 - Solar sails are large and lightweight reflective structures that are propelled by solar radiation pressure. This chapter covers their orbital and attitude dynamics and control. First, the advantages and limitations of solar sails are discussed and their history and development status is outlined. Because the dynamics of solar sails is governed by the (thermo-)optical properties of the sail film, the basic solar radiation pressure force models have to be described and compared before parameters to measure solar sail performance can be defined. The next part covers the orbital dynamics of solar sails for heliocentric motion, planetocentric motion, and motion at Lagrangian equilibrium points. Afterwards, some advanced solar radiation pressure force models are described, which allow to quantify the thrust force on solar sails of arbitrary shape, the effects of temperature, of light incidence angle, of surface roughness, and the effects of optical degradation of the sail film in the space environment. The orbital motion of a solar sail is strongly coupled to its rotational motion, so that the attitude control of these soft and flexible structures is very challenging, especially for planetocentric orbits that require fast attitude maneuvers. Finally, some potential attitude control methods are sketched and selection criteria are given. KW - solar sail KW - sailcraft KW - orbital dynamics KW - orbit control KW - attitude dynamics Y1 - 2010 U6 - http://dx.doi.org/10.1002/9780470686652.eae292 PB - Wiley CY - Hoboken ER - TY - JOUR A1 - Dachwald, Bernd T1 - Optimization of very-low-thrust trajectories using evolutionary neurocontrol JF - Acta Astronautica N2 - Searching optimal interplanetary trajectories for low-thrust spacecraft is usually a difficult and time-consuming task that involves much experience and expert knowledge in astrodynamics and optimal control theory. This is because the convergence behavior of traditional local optimizers, which are based on numerical optimal control methods, depends on an adequate initial guess, which is often hard to find, especially for very-low-thrust trajectories that necessitate many revolutions around the sun. The obtained solutions are typically close to the initial guess that is rarely close to the (unknown) global optimum. Within this paper, trajectory optimization problems are attacked from the perspective of artificial intelligence and machine learning. Inspired by natural archetypes, a smart global method for low-thrust trajectory optimization is proposed that fuses artificial neural networks and evolutionary algorithms into so-called evolutionary neurocontrollers. This novel method runs without an initial guess and does not require the attendance of an expert in astrodynamics and optimal control theory. This paper details how evolutionary neurocontrol works and how it could be implemented. The performance of the method is assessed for three different interplanetary missions with a thrust to mass ratio <0.15mN/kg (solar sail and nuclear electric). Y1 - 2005 SN - 1879-2030 VL - 57 IS - 2-8 SP - 175 EP - 185 PB - Elsevier CY - Amsterdam [u.a.] ER - TY - CHAP A1 - Dachwald, Bernd T1 - Radiation pressure force model for an ideal laser-enhanced solar sail T2 - 4th International Symposium on Solar Sailing N2 - The concept of a laser-enhanced solar sail is introduced and the radiation pressure force model for an ideal laser-enhanced solar sail is derived. A laser-enhanced solar sail is a “traditional” solar sail that is, however, not solely propelled by solar radiation, but additionally by a laser beam that illuminates the sail. The additional laser radiation pressure increases the sail's propulsive force and can give, depending on the location of the laser source, more control authority over the direction of the solar sail’s propulsive force vector. This way, laser-enhanced solar sails may augment already existing solar sail mission concepts and make novel mission concepts feasible. Y1 - 2017 N1 - 4th International Symposium on Solar Sailing 17-20 January 2017, Kyōto, Japan SP - 1 EP - 5 ER - TY - CHAP A1 - Dachwald, Bernd T1 - Solar sail performance requirements for missions to the outer solar system and beyond T2 - 55th International Astronautical Congress 2004 N2 - Solar sails enable missions to the outer solar system and beyond, although the solar radiation pressure decreases with the square of solar distance. For such missions, the solar sail may gain a large amount of energy by first making one or more close approaches to the sun. Within this paper, optimal trajectories for solar sail missions to the outer planets and into near interstellar space (200 AU) are presented. Thereby, it is shown that even near/medium-term solar sails with relatively moderate performance allow reasonable transfer times to the boundaries of the solar system. Y1 - 2004 U6 - http://dx.doi.org/10.2514/6.IAC-04-S.P.11 N1 - 55th International Astronautical Congress 2004 - Vancouver, Canada SP - 1 EP - 9 ER - TY - JOUR A1 - Dachwald, Bernd A1 - Ball, Andrew J. A1 - Ulamec, Stephan A1 - Price, Michael E. T1 - A small mission for in situ exploration of a primitive binary near-Earth asteroid / Ball, Andrew J. ; Ulamec, Stephan ; Dachwald, Bernd ; Price, Michael E. ; [u.a.] JF - Advances in Space Research. 43 (2009), H. 2 Y1 - 2009 SN - 0273-1177 SP - 317 EP - 324 PB - Elsevier CY - Amsterdam ER - TY - CHAP A1 - Dachwald, Bernd A1 - Baturkin, Volodymyr A1 - Coverstone, Victoria A1 - Diedrich, Ben A1 - Garbe, Gregory A1 - Görlich, Marianne A1 - Leipold, Manfred A1 - Lura, Franz A1 - Macdonald, Malcolm A1 - McInnes, Colin A1 - Mengali, Giovanni A1 - Quarta, Alessandro A1 - Rios-Reyes, Leonel A1 - Scheeres, Daniel J. A1 - Seboldt, Wolfgang A1 - Wie, Bong T1 - Potential effects of optical solar sail degredation on trajectory design T2 - AAS/AIAA Astrodynamics Specialist N2 - The optical properties of the thin metalized polymer films that are projected for solar sails are assumed to be affected by the erosive effects of the space environment. Their degradation behavior in the real space environment, however, is to a considerable degree indefinite, because initial ground test results are controversial and relevant inspace tests have not been made so far. The standard optical solar sail models that are currently used for trajectory design do not take optical degradation into account, hence its potential effects on trajectory design have not been investigated so far. Nevertheless, optical degradation is important for high-fidelity solar sail mission design, because it decreases both the magnitude of the solar radiation pressure force acting on the sail and also the sail control authority. Therefore, we propose a simple parametric optical solar sail degradation model that describes the variation of the sail film’s optical coefficients with time, depending on the sail film’s environmental history, i.e., the radiation dose. The primary intention of our model is not to describe the exact behavior of specific film-coating combinations in the real space environment, but to provide a more general parametric framework for describing the general optical degradation behavior of solar sails. Using our model, the effects of different optical degradation behaviors on trajectory design are investigated for various exemplary missions. Y1 - 2005 N1 - 2005 AAS/AIAA Astrodynamics Specialist Conference, 7-11.08.2005. Lake Tahoe, California https://www.space-flight.org/AAS_meetings/2005_astro/2005_astro.html SP - 1 EP - 23 ER - TY - JOUR A1 - Dachwald, Bernd A1 - Baturkin, Volodymyr A1 - Coverstone, Victoria L. A1 - Dietrich, Benjamin A1 - Garbe, Gregory P. A1 - Görlich, Marianne A1 - Leipold, Manfred A1 - Lura, Franz A1 - Macdonald, Malcolm A1 - McInnes, Colin R. A1 - Mengali, Giovanni A1 - Quatra, Alessandro A. A1 - Rios-Reyes, Leonel A1 - Scheeres, Daniel J. A1 - Seboldt, Wolfgang A1 - Wie, Bong T1 - Potential Effects of Optical Solar Sail Degradation on Interplanetary Trajectory Design JF - Astrodynamics 2005 : proceedings of the AAS/AIAA astrodynamics conference held August 7 - 11, 2005, South Lake Tahoe, California / ed. by Bobby G. Williams. - Pt. 3. - (Advances in the astronautical sciences ; 123,3) Y1 - 2006 UR - http://www.spacesailing.net/paper/200508_LakeTahoe_Dachwald+.pdf SN - 0-87703-527-X N1 - Astrodynamics Conference <2005, South Lake Tahoe, Calif.> ; American Astronautical Society ; Number: AAS-05-413 SP - 2569 EP - 2592 PB - Univelt CY - San Diego, Calif. ER - TY - CHAP A1 - Dachwald, Bernd A1 - Boehnhardt, Herrmann A1 - Broj, Ulrich A1 - Geppert, Ulrich R. M. E. A1 - Grundmann, Jan-Thimo A1 - Seboldt, Wolfgang A1 - Seefeldt, Patric A1 - Spietz, Peter A1 - Johnson, Les A1 - Kührt, Ekkehard A1 - Mottola, Stefano A1 - Macdonald, Malcolm A1 - McInnes, Colin R. A1 - Vasile, Massimiliano A1 - Reinhard, Ruedeger T1 - Gossamer roadmap technology reference study for a multiple NEO Rendezvous Mission T2 - Advances in solar sailing N2 - A technology reference study for a multiple near-Earth object (NEO) rendezvous mission with solar sailcraft is currently carried out by the authors of this paper. The investigated mission builds on previous concepts, but adopts a strong micro-spacecraft philosophy based on the DLR/ESA Gossamer technology. The main scientific objective of the mission is to explore the diversity of NEOs. After direct interplanetary insertion, the solar sailcraft should—within less than 10 years—rendezvous three NEOs that are not only scientifically interesting, but also from the point of human spaceight and planetary defense. In this paper, the objectives of the study are outlined and a preliminary potential mission profile is presented. Y1 - 2014 SN - 978-3-642-34906-5 (Print) ; 978-3-642-34907-2 (E-Book) SP - 211 EP - 226 PB - Springer CY - Berlin [u.a.] ER - TY - JOUR A1 - Dachwald, Bernd A1 - Carnelli, I. A1 - Vasile, M. T1 - Low-Thrust Gravity Assist Trajectory Optimization Using Evolutionary Neurocontrollers / I. Carnelli ; B. Dachwald ; M. Vasile ... JF - Astrodynamics 2005 : proceedings of the AAS/AIAA astrodynamics conference held August 7 - 11, 2005, South Lake Tahoe, California / ed. by Bobby G. Williams. - Pt. 3. - (Advances in the astronautical sciences ; 123,3) Y1 - 2006 SN - 0-87703-527-X N1 - Astrodynamics Conference <2005, South Lake Tahoe, Calif.> ; American Astronautical Society ; Number: AAS-05-374 SP - 1911 EP - 1928 PB - Univelt CY - San Diego, Calif. ER - TY - JOUR A1 - Dachwald, Bernd A1 - Carnelli, I. A1 - Vasile, M. T1 - Optimizing low-thrust gravity assist interplanetary trajectories using evolutionary neurocontrollers / I. Carnelli ; B. Dachwald ; M. Vasile JF - IEEE Congress on Evolutionary Computation, 2007 : CEC 2007 ; 25 - 28 September 2007, Singapore Y1 - 2007 SN - 978-1-424-41339-3 N1 - ISBN 10: 1-424-41339-7 ; IEEE Congress on Evolutionary Computation <2007, Singapore> ; Institute of Electrical and Electronics Engineers ; Nebent: CEC 2007 ; Parallel als Online-Ausg. erschienen SP - 965 EP - 972 PB - IEEE Service Center CY - Piscataway, NJ ER - TY - JOUR A1 - Dachwald, Bernd A1 - Carnelli, I. A1 - Vasile, M. T1 - Evolutionary Neurocontrol as a Novel Method for Low-Thrust Gravity Assist Trajectory Optimization / I. Carnelli ; B. Dachwald ; M. Vasile JF - Proceedings of the Twenty-Fifth International Symposium on Space Technology and Science (Selected papers) : Kanazawa, [June 4 through June 11, 2006, at Kanazawa-shi Kanko Kaikan in Kanazawa city] / [Japan Society for Aeronautical and Space Sciences. Kohtaro Matsumoto [ed.-in-chief] Y1 - 2006 SN - 4-99005-002-9 N1 - International Symposium on Space Technology and Science <25, 2006, Kanazawa> ; ISTS 2006-d-46 SP - 569 EP - 574 PB - JSASS CY - Tokyo ER - TY - JOUR A1 - Dachwald, Bernd A1 - Carnelli, Ian A1 - Vasile, Massimiliano T1 - Evolutionary Neurocontrol: A Novel Method for Low-Thrust Gravity-Assist Trajectory Optimization / Carnelli, Ian ; Dachwald, Bernd ; Vasile, Massimiliano JF - Journal of guidance control and dynamics. 32 (2009), H. 2 Y1 - 2009 SN - 0731-5090 SP - 616 EP - 625 PB - AIAA CY - Reston, Va. ER - TY - CHAP A1 - Dachwald, Bernd A1 - Feldmann, Marco A1 - Espe, Clemens A1 - Plescher, Engelbert A1 - Konstantinidis, K. A1 - Forstner, R. T1 - Enceladus explorer - A maneuverable subsurface probe for autonomous navigation through deep ice T2 - 63rd International Astronautical Congress 2012, IAC 2012; Naples; Italy; 1 October 2012 through 5 October 2012. (Proceedings of the International Astronautical Congress, IAC ; 3) Y1 - 2012 SN - 978-1-62276-979-7 SP - 1756 EP - 1766 PB - Curran CY - Red Hook, NY ER - TY - JOUR A1 - Dachwald, Bernd A1 - Kahle, Ralph A1 - Wie, Bong T1 - Solar Sailing Kinetic Energy Impactor (KEI) Mission Design Tradeoffs for Impacting and Deflecting Asteroid 99942 Apophis JF - AIAA Guidance, Navigation, and Control Conference & Exhibit - AIAA Atmospheric Flight Mechanics Conference & Exhibit - AIAA Modeling and Simulation Technologies Conference & Exhibit - AIAA/AAS Astrodynamics Specialist Conference & Exhibit : [21 - 24 August 2006, Keystone, Colorado ; papers]. - (AIAA meeting papers on disc ; [11.]2006,19-20 ) Y1 - 2006 SN - 1-56347-802-1 N1 - American Institute of Aeronautics and Astronautics ; American Astronautical Society ; AIAA/AAS Astrodynamics Specialist Conference & Exhibit <2006, Keystone, Colo.> ; AIAA paper number: AIAA-2006-6178 SP - 1 EP - 20 PB - American Institute of Aeronautics and Astronautics CY - Reston, Va. ER - TY - CHAP A1 - Dachwald, Bernd A1 - Kahle, Ralph A1 - Wie, Bong T1 - Solar sail Kinetic Energy Impactor (KEI) mission design tradeoffs for impacting and deflecting asteroid 99942 Apophis T2 - AIAA/AAS Astrodynamics Specialist Conference and Exhibit N2 - Near-Earth asteroid 99942 Apophis provides a typical example for the evolution of asteroid orbits that lead to Earth-impacts after a close Earth-encounter that results in a resonant return. Apophis will have a close Earth-encounter in 2029 with potential very close subsequent Earth-encounters (or even an impact) in 2036 or later, depending on whether it passes through one of several so-called gravitational keyholes during its 2029-encounter. Several pre-2029-deflection scenarios to prevent Apophis from doing this have been investigated so far. Because the keyholes are less than 1 km in size, a pre-2029 kinetic impact is clearly the best option because it requires only a small change in Apophis' orbit to nudge it out of a keyhole. A single solar sail Kinetic Energy Impactor (KEI) spacecraft that impacts Apophis from a retrograde trajectory with a very high relative velocity (75-80 km/s) during one of its perihelion passages at about 0.75 AU would be a feasible option to do this. The spacecraft consists of a 160 m x 160 m, 168 kg solar sail assembly and a 150 kg impactor. Although conventional spacecraft can also achieve the required minimum deflection of 1 km for this approx. 320 m-sized object from a prograde trajectory, our solar sail KEI concept also allows the deflection of larger objects. In this paper, we also show that, even after Apophis has flown through one of the gravitational keyholes in 2029, solar sail Kinetic Energy Impactor (KEI) spacecraft are still a feasible option to prevent Apophis from impacting the Earth, but many KEIs would be required for consecutive impacts to increase the total Earth-miss distance to a safe value. In this paper, we elaborate potential pre- and post-2029 KEI impact scenarios for a launch in 2020, and investigate tradeoffs between different mission parameters. KW - Solar Sail KW - Asteroid Deflection KW - Planetary Protection KW - Trajectory Optimization Y1 - 2006 U6 - http://dx.doi.org/10.2514/6.2006-6178 N1 - AIAA/AAS Astrodynamics Specialist Conference and Exhibit, 21 August 2006 - 24 August 2006, Keystone, Colorado(USA). SP - 1 EP - 20 ER - TY - CHAP A1 - Dachwald, Bernd A1 - Kahle, Ralph A1 - Wie, Bong T1 - Head-on impact deflection of NEAs: a case study for 99942 Apophis T2 - Planetary Defense Conference 2007 N2 - Near-Earth asteroid (NEA) 99942 Apophis provides a typical example for the evolution of asteroid orbits that lead to Earth-impacts after a close Earth-encounter that results in a resonant return. Apophis will have a close Earth-encounter in 2029 with potential very close subsequent Earth-encounters (or even an impact) in 2036 or later, depending on whether it passes through one of several less than 1 km-sized gravitational keyholes during its 2029-encounter. A pre-2029 kinetic impact is a very favorable option to nudge the asteroid out of a keyhole. The highest impact velocity and thus deflection can be achieved from a trajectory that is retrograde to Apophis orbit. With a chemical or electric propulsion system, however, many gravity assists and thus a long time is required to achieve this. We show in this paper that the solar sail might be the better propulsion system for such a mission: a solar sail Kinetic Energy Impactor (KEI) spacecraft could impact Apophis from a retrograde trajectory with a very high relative velocity (75-80 km/s) during one of its perihelion passages. The spacecraft consists of a 160 m × 160 m, 168 kg solar sail assembly and a 150 kg impactor. Although conventional spacecraft can also achieve the required minimum deflection of 1 km for this approx. 320 m-sized object from a prograde trajectory, our solar sail KEI concept also allows the deflection of larger objects. For a launch in 2020, we also show that, even after Apophis has flown through one of the gravitational keyholes in 2029, the solar sail KEI concept is still feasible to prevent Apophis from impacting the Earth, but many KEIs would be required for consecutive impacts to increase the total Earth-miss distance to a safe value Y1 - 2007 N1 - Planetary Defense Conference 2007, Wahington D.C., USA, 05-08 March 2007 SP - 1 EP - 12 ER - TY - JOUR A1 - Dachwald, Bernd A1 - Leipold, M. A1 - Fichtner, H. T1 - Heliopause Explorer - A Sailcraft Mission to the Outer Boundaries of the Solar System / M. Leipold ; H. Fichtner ; B. Heber ... B. Dachwald ... JF - Proceedings of the Fifth IAA International Conference on Low Cost Planetary Missions : 24 - 26 September 2003, ESTEC, Noordwijk, the Netherlands / [comp. by R. A. Harris] Y1 - 2003 SN - 92-9092-853-0 N1 - International Conference on Low Cost Planetary Missions <5, 2003, Noordwijk> ; International Academy of Astronautics ; European Space Research and Technology Centre SP - 367 EP - 375 PB - ESA CY - Noordwijk ER - TY - JOUR A1 - Dachwald, Bernd A1 - MacDonald, Malcolm A1 - McInnes, Colin R. T1 - Heliocentric Solar Sail Orbit Transfers with Locally Optimal Control Laws / Malcolm Macdonald ; Colin McInnes ; Bernd Dachwald JF - Journal of Spacecraft and Rockets. 44 (2007), H. 1 Y1 - 2007 SN - 0022-4650 SP - 273 EP - 276 ER - TY - JOUR A1 - Dachwald, Bernd A1 - McDonald, Malcolm A1 - McInnes, Colin R. A1 - Mengali, Giovanni T1 - Impact of Optical Degradation on Solar Sail Mission Performance JF - Journal of Spacecraft and Rockets. 44 (2007), H. 4 Y1 - 2007 SN - 0022-4650 N1 - 2. ISSN: 1533-6794 SP - 740 EP - 749 ER - TY - JOUR A1 - Dachwald, Bernd A1 - Mengali, Giovanni A1 - Quarta, Alessandrao A. A1 - Macdonald, Malcolm T1 - Parametric Model and Optimal Control of Solar Sails with Optical Degradation JF - Journal of guidance, control, and dynamics. 29 (2006), H. 5 Y1 - 2006 SN - 0162-3192 N1 - 2. ISSN: 0731-5090 SP - 1170 EP - 1178 ER - TY - CHAP A1 - Dachwald, Bernd A1 - Mengali, Giovanni A1 - Quarta, Alessandro A A1 - Macdonald, Malcolm A1 - McInnes, Colin R T1 - Optical solar sail degradation modelling T2 - 1st International Symposium on Solar Sailing N2 - We propose a simple parametric OSSD model that describes the variation of the sail film's optical coefficients with time, depending on the sail film's environmental history, i.e., the radiation dose. The primary intention of our model is not to describe the exact behavior of specific film-coating combinations in the real space environment, but to provide a more general parametric framework for describing the general optical degradation behavior of solar sails. Y1 - 2007 N1 - 1st International Symposium on Solar Sailing 27–29 June 2007, Herrsching, Germany SP - 1 EP - 27 ER - TY - JOUR A1 - Dachwald, Bernd A1 - Mengali, Giovanni A1 - Quarta, Alessandro A. A1 - Circi, Christian T1 - Refined Solar Sail Force Model with Mission Application / Giovanni Mengali ; Alessandro A. Quarta , Christian Circi ; Bernd Dachwald JF - Journal of Guidance, Control, and Dynamics. 30 (2007), H. 2 Y1 - 2007 SN - 0162-3192 N1 - 2. ISBN: 0731-5090 SP - 512 EP - 520 ER - TY - CHAP A1 - Dachwald, Bernd A1 - Mikucki, Jill A. A1 - Tulaczyk, Slawek A1 - Digel, Ilya A1 - Feldmann, Marco A1 - Espe, Clemens A1 - Plescher, Engelbert A1 - Xu, Changsheng T1 - IceMole - a maneuverable probe for clean in-situ analysis and sampling of subsurface ice and subglacial aquatic ecosystems : extended abstract / SCAR Open Science Conference 2012, Session 29: Advancing Clean Technologies for Exploration of Glacial Aquatic Ecosystems N2 - The ”IceMole“ is a novel maneuverable subsurface ice probe for clean in-situ analysis and sampling of subsurface ice and subglacial water/brine. It is developed and build at FH Aachen University of Applied Sciences’ Astronautical Laboratory. A first prototype was successfully tested on the Swiss Morteratsch glacier in 2010. Clean sampling is achieved with a hollow ice screw (as it is used in mountaineering) at the tip of the probe. Maneuverability is achieved with a differentially heated melting head. Funded by the German Space Agency (DLR), a consortium led by FH Aachen currently develops a much more advanced IceMole probe, which includes a sophisticated system for obstacle avoidance, target detection, and navigation in the ice. We intend to use this probe for taking clean samples of subglacial brine at the Blood Falls (McMurdo Dry Valleys, East Antarctica) for chemical and microbiological analysis. In our conference contribution, we 1) describe the IceMole design, 2) report the results of the field tests of the first prototype on the Morteratsch glacier, 3) discuss the probe’s potential for the clean in-situ analysis and sampling of subsurface ice and subglacial liquids, and 4) outline the way ahead in the development of this technology. KW - Eisschicht KW - Sonde KW - subsurface ice KW - subglacial aquatic ecosystems Y1 - 2012 ER - TY - JOUR A1 - Dachwald, Bernd A1 - Mikucki, Jill A1 - Tulaczyk, Slawek A1 - Digel, Ilya A1 - Espe, Clemens A1 - Feldmann, Marco A1 - Francke, Gero A1 - Kowalski, Julia A1 - Xu, Changsheng T1 - IceMole : A maneuverable probe for clean in situ analysis and sampling of subsurface ice and subglacial aquatic ecosystems JF - Annals of Glaciology N2 - There is significant interest in sampling subglacial environments for geobiological studies, but they are difficult to access. Existing ice-drilling technologies make it cumbersome to maintain microbiologically clean access for sample acquisition and environmental stewardship of potentially fragile subglacial aquatic ecosystems. The IceMole is a maneuverable subsurface ice probe for clean in situ analysis and sampling of glacial ice and subglacial materials. The design is based on the novel concept of combining melting and mechanical propulsion. It can change melting direction by differential heating of the melting head and optional side-wall heaters. The first two prototypes were successfully tested between 2010 and 2012 on glaciers in Switzerland and Iceland. They demonstrated downward, horizontal and upward melting, as well as curve driving and dirt layer penetration. A more advanced probe is currently under development as part of the Enceladus Explorer (EnEx) project. It offers systems for obstacle avoidance, target detection, and navigation in ice. For the EnEx-IceMole, we will pay particular attention to clean protocols for the sampling of subglacial materials for biogeochemical analysis. We plan to use this probe for clean access into a unique subglacial aquatic environment at Blood Falls, Antarctica, with return of a subglacial brine sample. KW - Antarctic Glaciology KW - Extraterrestrial Glaciology KW - Glaciological instruments and methods KW - Subclacial exploration KW - Subglacial lakes Y1 - 2014 U6 - http://dx.doi.org/10.3189/2014AoG65A004 SN - 1727-5644 VL - 55 IS - 65 SP - 14 EP - 22 PB - Cambridge University Press CY - Cambridge ER - TY - JOUR A1 - Dachwald, Bernd A1 - Ohndorf, A. T1 - 1st ACT Global Trajectory Optimisation Competition : Results found at DLR JF - Acta Astronautica. 61 (2007), H. 9 Y1 - 2007 SN - 0094-5765 N1 - Global Trajectory Optimization ; Results of the First Competition Organised by the Advanced Concept Team (ACT) of the European Space Agency (ESA) SP - 742 EP - 752 ER - TY - JOUR A1 - Dachwald, Bernd A1 - Ohndorf, A. A1 - Gill, E. T1 - Optimization of low-thrust Earth-Moon transfers using evolutionary neurocontrol / Ohndorf, A. ; Dachwald, B. ; Gill, E. JF - IEEE Congress on Evolutionary Computation, 2009. CEC '09. Y1 - 2009 SN - 978-1-4244-2958-5 SP - 358 EP - 364 ER - TY - JOUR A1 - Dachwald, Bernd A1 - Ohndorf, A. A1 - Wie, Bong T1 - Solar Sail Trajectory Optimization for the Solar Polar Imager (SPI) Mission JF - AIAA Guidance, Navigation, and Control Conference & Exhibit - AIAA Atmospheric Flight Mechanics Conference & Exhibit - AIAA Modeling and Simulation Technologies Conference & Exhibit - AIAA/AAS Astrodynamics Specialist Conference & Exhibit : [21 - 24 August 2006, Keystone, Colorado ; papers]. - (AIAA meeting papers on disc ; [11.]2006,19-20 ) Y1 - 2006 SN - 1-56347-802-1 N1 - American Institute of Aeronautics and Astronautics ; American Astronautical Society ; AIAA/AAS Astrodynamics Specialist Conference & Exhibit <2006, Keystone, Colo.> ; AIAA paper number: AIAA-2006-6177 PB - American Institute of Aeronautics and Astronautics CY - Reston, Va. ER - TY - CHAP A1 - Dachwald, Bernd A1 - Ohndorf, Andreas T1 - Global optimization of continuous-thrust trajectories using evolutionary neurocontrol T2 - Modeling and Optimization in Space Engineering N2 - Searching optimal continuous-thrust trajectories is usually a difficult and time-consuming task. The solution quality of traditional optimal-control methods depends strongly on an adequate initial guess because the solution is typically close to the initial guess, which may be far from the (unknown) global optimum. Evolutionary neurocontrol attacks continuous-thrust optimization problems from the perspective of artificial intelligence and machine learning, combining artificial neural networks and evolutionary algorithms. This chapter describes the method and shows some example results for single- and multi-phase continuous-thrust trajectory optimization problems to assess its performance. Evolutionary neurocontrol can explore the trajectory search space more exhaustively than a human expert can do with traditional optimal-control methods. Especially for difficult problems, it usually finds solutions that are closer to the global optimum. Another fundamental advantage is that continuous-thrust trajectories can be optimized without an initial guess and without expert supervision. Y1 - 2019 SN - 978-3-030-10501-3 SN - 978-3-030-10500-6 U6 - http://dx.doi.org/10.1007/978-3-030-10501-3_2 N1 - Springer Optimization and Its Applications, vol 144 gedruckt unter der Signatur 21 ZSS 46 in der Bereichsbibliothek Eupener Str. vorhanden SP - 33 EP - 57 PB - Springer CY - Cham ER - TY - JOUR A1 - Dachwald, Bernd A1 - Schmidt, Tanja D. A1 - Seboldt, Wolfgang A1 - Auweter-Kurtz, T1 - Flight Opportunities from Mars to Earth for Piloted Missions Using Continuous Thrust Propulsion / Schmidt, Tanja D. ; Dachwald, Bernd ; Seboldt, Wolfgang ; Auweter-Kurtz, Monika Y1 - 2003 N1 - 39th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit 20-23 July 2003, Huntsville, Alabama ; AIAA 2003-4573 SP - 1 EP - 9 PB - - ER - TY - JOUR A1 - Dachwald, Bernd A1 - Seboldt, W. T1 - Multiple Near-Earth Asteroid Rendezvous and Sample Return Using First Generation Solar Sailcraft JF - Acta Astronautica. 57 (2005), H. 11 Y1 - 2005 SN - 0094-5765 SP - 864 EP - 875 ER - TY - JOUR A1 - Dachwald, Bernd A1 - Seboldt, W. T1 - Optimization of Interplanetary Rendezvous Trajectories for Solar Sailcraft Using a Neurocontroller JF - A collection of technical papers / AIAA Astrodynamics Specialist Conference : Monterey, California, 5 - 8 August 2002. - Vol. 2 Y1 - 2002 SN - 1-56347-549-9 N1 - Astrodynamics Specialist Conference <2002, Monterey, Calif.> American Institute of Aeronautics and Astronautics ; AIAA paper number: AIAA-2002-4989 SP - 1263 EP - 1270 PB - American Institute of Aeronautics and Astronautics CY - Reston, Va. ER - TY - JOUR A1 - Dachwald, Bernd A1 - Seboldt, W. T1 - Solar Sails for Near- and Medium-Term Scientific Deep Space Missions / W. Sebolt ; B. Dachwald JF - In-space propulsion : edited book of proceedings of the 10-IWCP, the 10th International Workshop on Combustion and Propulsion held in Lerici, La Spezia, Italy, 21-25 September 2003 / [ed.: Luigi T. DeLuca] Y1 - 2005 N1 - Paper 31 ; International workshop on combustion and propulsion <10, 2003, Lerici> PB - SP Lab, Politecnico di Milano CY - Milano ER - TY - JOUR A1 - Dachwald, Bernd A1 - Seboldt, W. T1 - Solar Sails — Propellantless Propulsion for Near- and Medium-Term Deep-Space Missions / W. Seboldt ; B. Dachwald JF - Advanced Propulsion Systems and Technologies, Today to 2020 / Claudio Bruno (ed.) ... - (Progress in Astronautics and Aeronautics Series ; 223) Y1 - 2008 SN - 978-1-56347-929-8 N1 - ISBN 10: 1-56347-929-X ; American Institute of Aeronautics and Astronautics PB - AIAA CY - Reston, Va. ER - TY - JOUR A1 - Dachwald, Bernd A1 - Seboldt, W. A1 - Loeb, H. W A1 - Schartner, K.-H. T1 - Main Belt Asteroid Sample Return Mission Using Solar Electric Propulsion JF - Acta Astronautica. 63 (2008), H. 1-4 Y1 - 2008 SN - 0094-5765 N1 - International Astronautical Federation Congress <58, 2007, Hyderabad> ; International Astronautical Congress <58, 2007, Hyderabad> ; IAC-07-A3.5.07 SP - 91 EP - 101 ER - TY - JOUR A1 - Dachwald, Bernd A1 - Seboldt, W. A1 - Lämmerzahl, W. T1 - Solar Sail Propulsion: An Enabling Technology for Fundamental Physics Missions JF - Lasers, Clocks and Drag Free Control : Exploration of Relativistic Gravity in Space / by Hansjörg Dittus ..., eds. - ( Astrophysics and Space Science Library ; 349) Y1 - 2008 SN - 978-3-540-34376-9 SP - 379 EP - 398 PB - Springer CY - Berlin [u.a.] ER - TY - JOUR A1 - Dachwald, Bernd A1 - Seboldt, W. A1 - Richter, L. T1 - Multiple rendezvous and sample return missions to near-Earth objects using solar sailcraft / Dachwald, B. ; Seboldt, W. ; Richter, L. JF - Acta Astronautica. 59 (2006), H. 8-11 Y1 - 2006 SN - 0094-5765 N1 - International Conference on Low Cost Planetary Missions <5, 2003, Noordwijk> ; Selected Proceedings SP - 768 EP - 776 ER - TY - JOUR A1 - Dachwald, Bernd A1 - Seboldt, W. A1 - Richter, L. T1 - Multiple Rendezvous and Sample Return Missions to Near-Earth Asteroids Using Solar Sailcraft JF - Proceedings of the Fifth IAA International Conference on Low Cost Planetary Missions : 24 - 26 September 2003, ESTEC, Noordwijk, the Netherlands / [comp. by R. A. Harris] Y1 - 2003 SN - 92-9092-853-0 N1 - International Conference on Low Cost Planetary Missions <5, 2003, Noordwijk> ; International Academy of Astronautics ; European Space Research and Technology Centre SP - 351 EP - 358 PB - ESA CY - Noordwijk ER - TY - JOUR A1 - Dachwald, Bernd A1 - Seboldt, Wolfgang T1 - Solar sailcraft of the first generation technology development / Seboldt, Wolfgang ; Dachwald, Bernd Y1 - 2003 N1 - 54th International Astronautical Congress of the International Astronautical Federation, the International Academy of Astronautics, and the International Institute of Space Law 29 September - 3 October 2003, Bremen, Germany IAC-03-S.03 ER - TY - JOUR A1 - Dachwald, Bernd A1 - Seboldt, Wolfgang T1 - Solar sailcraft of the first generation mission applications to near-earth asteroids Y1 - 2003 N1 - 54th International Astronautical Congress of the International Astronautical Federation, the International Academy of Astronautics, and the International Institute of Space Law 29 September - 3 October 2003, Bremen, Germany IAC-03-Q.5.06 ER - TY - CHAP A1 - Dachwald, Bernd A1 - Seboldt, Wolfgang A1 - Häusler, Bernd T1 - Performance requirements for near-term interplanetary solar sailcraft missions T2 - 6th International AAAF Symposium on Space Propulsion: Propulsion for Space Transportation of the XXIst Century N2 - Solar sailcraft provide a wide range of opportunities for high-energy low-cost missions. To date, most mission studies require a rather demanding performance that will not be realized by solar sailcraft of the first generation. However, even with solar sailcraft of moderate performance, scientifically relevant missions are feasible. This is demonstrated with a Near Earth Asteroid sample return mission and various planetary rendezvous missions. Y1 - 2002 N1 - 6th International AAAF Symposium on Space Propulsion: Propulsion for Space Transportation of the XXIst Century, Versailles, France, 14-16 May 2002 ER - TY - CHAP A1 - Dachwald, Bernd A1 - Seboldt, Wolfgang A1 - Loeb, Horst W. A1 - Schartner, Karl-Heinz T1 - A comparison of SEP and NEP for a main belt asteroid sample return mission T2 - 7th International Symposium on Launcher Technologies, Barcelona, Spain, 02-05 April 2007 N2 - Innovative interplanetary deep space missions, like a main belt asteroid sample return mission, require ever larger velocity increments (∆V s) and thus ever more demanding propulsion capabilities. Providing much larger exhaust velocities than chemical high-thrust systems, electric low-thrust space-propulsion systems can significantly enhance or even enable such high-energy missions. In 1995, a European-Russian Joint Study Group (JSG) presented a study report on “Advanced Interplanetary Missions Using Nuclear-Electric Propulsion” (NEP). One of the investigated reference missions was a sample return (SR) from the main belt asteroid (19) Fortuna. The envisaged nuclear power plant, Topaz-25, however, could not be realized and also the worldwide developments in space reactor hardware stalled. In this paper, we investigate, whether such a mission is also feasible using a solar electric propulsion (SEP) system and compare our SEP results to corresponding NEP results. Y1 - 2007 SP - 1 EP - 10 ER - TY - JOUR A1 - Dachwald, Bernd A1 - Seboldt, Wolfgang A1 - Macdonald, Malcolm A1 - Mengali, Giovanni A1 - Quatra, Alessandro A. A1 - McInnes, Colin R. A1 - Rios-Reyes, Leonel A1 - Scheerers, Daniel J. A1 - Wie, Bong A1 - Görlich, Marianne A1 - Lura, Franz A1 - Diedrich, Benjamin A1 - Baturkin, Volodymyr A1 - Coverstone, Victoria L. A1 - Leipold, Manfred A1 - Garbe, Gregory P. T1 - Potential Solar Sail Degradation Effects on Trajectory and Attitude Control JF - AIAA Guidance, Navigation and Control Conference and Exhibit - AIAA Modeling and Simulation Technologies Conference and Exhibit - AIAA Atmospheric Flight Mechanics Conference and Exhibit : [San Francisco, California, 15 - 18 August 2005 ; papers]. - (AIAA meeting papers on disc ; [10.]2005,16-17) Y1 - 2005 SN - 1-56347-765-3 N1 - American Institute of Aeronautics and Astronautics ; AIAA Guidance, Navigation, and Control Conference and Exhibit <2005, San Francisco, Calif.> ; AIAA paper number: AIAA-2006-6172 Link "https://arc.aiaa.org/doi/book/10.2514/MGNC05" am 15.07.2022 nachgetragen Behr PB - American Institute of Aeronautics and Astronautics CY - Reston, Va. 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 - Dachwald, Bernd A1 - Turyshev, Slava G. A1 - Dittus, H. A1 - Shao, M. [u.a.] T1 - Fundamental Physics with the Laser Astrometric Test Of Relativity / S.G. Turyshev ; H. Dittus ; M. Shao ... B.Dachwald ... JF - Proceedings of the 39th ESLAB Symposium "Trends in Space Science and Cosmic Vision 2020" : 19 - 21 April 2005, ESTEC, Noordwijk, the Netherlands / European Space Agency. [Comp. by: F. Favata ...] . - (ESA SP ; 588) Y1 - 2005 SN - 9290928999 N1 - ISBN der CD-ROM-Ausg.: 9290928999 ; Symposium Trends in Space Science and Cosmic Vision 2020 <2005, Noordwijk> ; ESLAB symposium <39, 2005, Noordwijk> ; European Space Laboratory SP - 8 EP - 11 PB - ESA Publ. Div. CY - Noordwijk ER - TY - CHAP A1 - Dachwald, Bernd A1 - Ulamec, Stephan A1 - Biele, Jens T1 - Clean in situ subsurface exploration of icy environments in the solar system T2 - Habitability of other planets and satellites. - (Cellular origin, life in extreme habitats and astrobiology ; 28) N2 - "To assess the habitability of the icy environments in the solar system, for example, on Mars, Europa, and Enceladus, the scientific analysis of material embedded in or underneath their ice layers is very important. We consider self-steering robotic ice melting probes to be the best method to cleanly access these environments, that is, in compliance with planetary protection standards. The required technologies are currently developed and tested." Y1 - 2013 SN - 978-94-007-6545-0 (Druckausgabe) SN - 978-94-007-6546-7 (E-Book) SP - 367 EP - 397 PB - Springer CY - Dordrecht ER - TY - CHAP A1 - Dachwald, Bernd A1 - Ulamec, Stephan A1 - Kowalski, Julia A1 - Boxberg, Marc S. A1 - Baader, Fabian A1 - Biele, Jens A1 - Kömle, Norbert ED - Badescu, Viorel ED - Zacny, Kris ED - Bar-Cohen, Yoseph T1 - Ice melting probes T2 - Handbook of Space Resources N2 - The exploration of icy environments in the solar system, such as the poles of Mars and the icy moons (a.k.a. ocean worlds), is a key aspect for understanding their astrobiological potential as well as for extraterrestrial resource inspection. On these worlds, ice melting probes are considered to be well suited for the robotic clean execution of such missions. In this chapter, we describe ice melting probes and their applications, the physics of ice melting and how the melting behavior can be modeled and simulated numerically, the challenges for ice melting, and the required key technologies to deal with those challenges. We also give an overview of existing ice melting probes and report some results and lessons learned from laboratory and field tests. KW - Ice melting probe KW - Ice penetration KW - Icy moons KW - Ocean worlds KW - Mars Y1 - 2023 SN - 978-3-030-97912-6 (Print) SN - 978-3-030-97913-3 (Online) U6 - http://dx.doi.org/10.1007/978-3-030-97913-3_29 SP - 955 EP - 996 PB - Springer CY - Cham ER - TY - JOUR A1 - Dachwald, Bernd A1 - Ulamec, Stephan A1 - Postberg, Frank A1 - Sohl, Frank A1 - Vera, Jean-Pierre de A1 - Christoph, Waldmann A1 - Lorenz, Ralph D. A1 - Hellard, Hugo A1 - Biele, Jens A1 - Rettberg, Petra T1 - Key technologies and instrumentation for subsurface exploration of ocean worlds JF - Space Science Reviews N2 - In this chapter, the key technologies and the instrumentation required for the subsurface exploration of ocean worlds are discussed. The focus is laid on Jupiter’s moon Europa and Saturn’s moon Enceladus because they have the highest potential for such missions in the near future. The exploration of their oceans requires landing on the surface, penetrating the thick ice shell with an ice-penetrating probe, and probably diving with an underwater vehicle through dozens of kilometers of water to the ocean floor, to have the chance to find life, if it exists. Technologically, such missions are extremely challenging. The required key technologies include power generation, communications, pressure resistance, radiation hardness, corrosion protection, navigation, miniaturization, autonomy, and sterilization and cleaning. Simpler mission concepts involve impactors and penetrators or – in the case of Enceladus – plume-fly-through missions. Y1 - 2020 U6 - http://dx.doi.org/10.1007/s11214-020-00707-5 SN - 1572-9672 N1 - Corresponding author: Bernd Dachwald VL - 216 IS - Art. 83 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Dachwald, Bernd A1 - Wi, Bong T1 - Solar Sail Kinetic Energy Impactor Trajectory Optimization for an Asteroid-Deflection Mission JF - Journal of Spacecraft and Rockets. 44 (2007), H. 4 Y1 - 2007 SN - 0022-4650 N1 - 2. ISSN: 1533-6794 SP - 755 EP - 764 ER - TY - JOUR A1 - Dachwald, Bernd A1 - Wie, Bong T1 - Solar Sail Trajectory Optimization for Intercepting, Impacting, and Deflecting Near-Earth Asteroids JF - AIAA Guidance, Navigation and Control Conference and Exhibit - AIAA Modeling and Simulation Technologies Conference and Exhibit - AIAA Atmospheric Flight Mechanics Conference and Exhibit : [San Francisco, California, 15 - 18 August 2005 ; papers]. - (AIAA meeting papers on disc ; [10.]2005,16-17) Y1 - 2005 SN - 1-56347-765-3 N1 - American Institute of Aeronautics and Astronautics ; AIAA Guidance, Navigation, and Control Conference and Exhibit <2005, San Francisco, Calif.> ; AIAA paper number: AIAA-2006-6176 PB - American Institute of Aeronautics and Astronautics CY - Reston, Va. ER - TY - CHAP A1 - Dachwald, Bernd A1 - Wurm, P. T1 - Design concept and modeling of an advanced solar photon thruster T2 - Advances in the Astronautical Sciences N2 - The so-called "compound solar sail", also known as "Solar Photon Thruster" (SPT), holds the potential of providing significant performance advantages over the flat solar sail. Previous SPT design concepts, however, do not consider shadowing effects and multiple reflections of highly concentrated solar radiation that would inevitably destroy the gossamer sail film. In this paper, we propose a novel advanced SPT (ASPT) design concept that does not suffer from these oversimplifications. We present the equations that describe the thrust force acting on such a sail system and compare its performance with respect to the conventional flat solar sail. KW - solar sails Y1 - 2009 SN - 978-087703554-1 SN - 00653438 N1 - 19th AAS/AIAA Space Flight Mechanics Meeting; Savannah, GA; United States; 8 February 2009 through 12 February 2009 SP - 723 EP - 740 PB - American Astronautical Society CY - San Diego, Calif. ER - TY - CHAP A1 - Dachwald, Bernd A1 - Wurm, P. T1 - Mission analysis for an advanced solar photon thruster T2 - 60th International Astronautical Congress 2009, IAC 2009 N2 - The so-called "compound solar sail", also known as "Solar Photon Thruster" (SPT), is a solar sail design concept, for which the two basic functions of the solar sail, namely light collection and thrust direction, are uncoupled. In this paper, we introduce a novel SPT concept, termed the Advanced Solar Photon Thruster (ASPT). This model does not suffer from the simplified assumptions that have been made for the analysis of compound solar sails in previous studies. We present the equations that describe the force, which acts on the ASPT. After a detailed design analysis, the performance of the ASPT with respect to the conventional flat solar sail (FSS) is investigated for three interplanetary mission scenarios: An Earth-Venus rendezvous, where the solar sail has to spiral towards the Sun, an Earth-Mars rendezvous, where the solar sail has to spiral away from the Sun, and an Earth-NEA rendezvous (to near-Earth asteroid 1996FG3), where a large orbital eccentricity change is required. The investigated solar sails have realistic near-term characteristic accelerations between 0.1 and 0.2mm/s2. Our results show that a SPT is not superior to the flat solar sail unless very idealistic assumptions are made. KW - Interplanetary flight Y1 - 2009 SN - 978-161567908-9 N1 - 60th International Astronautical Congress 2009, IAC 2009; Daejeon; South Korea; 12 October 2009 through 16 October 2009 VL - Vol. 8 SP - 6838 EP - 6851 PB - Elsevier CY - Amsterdam ER - 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 - CHAP A1 - Dachwald, Bernd A1 - Xu, Changsheng A1 - Feldmann, Marco A1 - Plescher, Engelbert T1 - IceMole : Development of a novel subsurface ice probe and testing of the first prototype on the Morteratsch Glacier T2 - EGU General Assembly 2011 Vienna | Austria | 03 – 08 April 2011 N2 - We present the novel concept of a combined drilling and melting probe for subsurface ice research. This probe, named “IceMole”, is currently developed, built, and tested at the FH Aachen University of Applied Sciences’ Astronautical Laboratory. Here, we describe its first prototype design and report the results of its field tests on the Swiss Morteratsch glacier. Although the IceMole design is currently adapted to terrestrial glaciers and ice shields, it may later be modified for the subsurface in-situ investigation of extraterrestrial ice, e.g., on Mars, Europa, and Enceladus. If life exists on those bodies, it may be present in the ice (as life can also be found in the deep ice of Earth). Y1 - 2011 ER - TY - CHAP A1 - Dachwald, Bernd A1 - Xu, Changsheng A1 - Feldmann, Marco A1 - Plescher, Engelbert A1 - Digel, Ilya A1 - Artmann, Gerhard T1 - Development and testing of a subsurface probe for detection of life in deep ice : [abstract] N2 - We present the novel concept of a combined drilling and melting probe for subsurface ice research. This probe, named “IceMole”, is currently developed, built, and tested at the FH Aachen University of Applied Sciences’ Astronautical Laboratory. Here, we describe its first prototype design and report the results of its field tests on the Swiss Morteratsch glacier. Although the IceMole design is currently adapted to terrestrial glaciers and ice shields, it may later be modified for the subsurface in-situ investigation of extraterrestrial ice, e.g., on Mars, Europa, and Enceladus. If life exists on those bodies, it may be present in the ice (as life can also be found in the deep ice of Earth). KW - Eisschicht KW - Sonde KW - subsurface probe KW - subsurface ice research Y1 - 2011 ER - TY - JOUR A1 - Dadfar, Dryed Mohammadali A1 - Camozzi, Denise A1 - Darguzyte, Milita A1 - Roemhild, Karolin A1 - Varvarà, Paola A1 - Metselaar, Josbert A1 - Banala, Srinivas A1 - Straub, Marcel A1 - Güver, Nihan A1 - Engelmann, Ulrich M. A1 - Slabu, Ioana A1 - Buhl, Miriam A1 - Leusen, Jan van A1 - Kögerler, Paul A1 - Hermanns-Sachweh, Benita A1 - Schulz, Volkmar A1 - Kiessling, Fabian A1 - Lammers, Twan T1 - Size-isolation of superparamagnetic iron oxide nanoparticles improves MRI, MPI and hyperthermia performance JF - Journal of Nanobiotechnology N2 - Superparamagnetic iron oxide nanoparticles (SPION) are extensively used for magnetic resonance imaging (MRI) and magnetic particle imaging (MPI), as well as for magnetic fluid hyperthermia (MFH). We here describe a sequential centrifugation protocol to obtain SPION with well-defined sizes from a polydisperse SPION starting formulation, synthesized using the routinely employed co-precipitation technique. Transmission electron microscopy, dynamic light scattering and nanoparticle tracking analyses show that the SPION fractions obtained upon size-isolation are well-defined and almost monodisperse. MRI, MPI and MFH analyses demonstrate improved imaging and hyperthermia performance for size-isolated SPION as compared to the polydisperse starting mixture, as well as to commercial and clinically used iron oxide nanoparticle formulations, such as Resovist® and Sinerem®. The size-isolation protocol presented here may help to identify SPION with optimal properties for diagnostic, therapeutic and theranostic applications. Y1 - 2020 U6 - http://dx.doi.org/10.1186/s12951-020-0580-1 SN - 1477-3155 VL - 18 IS - Article number 22 SP - 1 EP - 13 PB - Nature Portfolio ER -