TY - CHAP A1 - Spurmann, Jörn A1 - Ohndorf, Andreas A1 - Dachwald, Bernd A1 - Seboldt, Wolfgang A1 - Löb, Horst A1 - Schartner, Karl-Heinz T1 - Interplanetary trajectory optimization for a sep mission to Saturn T2 - 60th International Astronautical Congress 2009 N2 - The recently proposed NASA and ESA missions to Saturn and Jupiter pose difficult tasks to mission designers because chemical propulsion scenarios are not capable of transferring heavy spacecraft into the outer solar system without the use of gravity assists. Thus our developed mission scenario based on the joint NASA/ESA Titan Saturn System Mission baselines solar electric propulsion to improve mission flexibility and transfer time. For the calculation of near-globally optimal low-thrust trajectories, we have used a method called Evolutionary Neurocontrol, which is implemented in the low-thrust trajectory optimization software InTrance. The studied solar electric propulsion scenario covers trajectory optimization of the interplanetary transfer including variations of the spacecraft's thrust level, the thrust unit's specific impulse and the solar power generator power level. Additionally developed software extensions enabled trajectory optimization with launcher-provided hyperbolic excess energy, a complex solar power generator model and a variable specific impulse ion engine model. For the investigated mission scenario, Evolutionary Neurocontrol yields good optimization results, which also hold valid for the more elaborate spacecraft models. Compared to Cassini/Huygens, the best found solutions have faster transfer times and a higher mission flexibility in general. KW - Spacecraft KW - Reusable Rocket Engines KW - Hybrid Propellants Y1 - 2009 SN - 9781615679089 N1 - 60th International Astronautical Congress 2009 (IAC 2009) Held 12-16 October 2009, Daejeon, Republic of Korea. SP - 5234 EP - 5248 ER - TY - JOUR A1 - Staat, Manfred T1 - Shakedown and ratchetting under tension-torsion loadings: analysis and experiments N2 - Structural design analyses are conducted with the aim of verifying the exclusion of ratchetting. To this end it is important to make a clear distinction between the shakedown range and the ratchetting range. The performed experiment comprised a hollow tension specimen which was subjected to alternating axial forces, superimposed with constant moments. First, a series of uniaxial tests has been carried out in order to calibrate a bounded kinematic hardening rule. The load parameters have been selected on the basis of previous shakedown analyses with the PERMAS code using a kinematic hardening material model. It is shown that this shakedown analysis gives reasonable agreement between the experimental and the numerical results. A linear and a nonlinear kinematic hardening model of two-surface plasticity are compared in material shakedown analysis. KW - Einspielen KW - Einspielen KW - Ratchetting KW - Zug-Druck Belastung KW - shakedown KW - ratchetting KW - tension–torsion loading Y1 - 2003 ER - TY - JOUR A1 - Staat, Manfred A1 - Vu, Duc-Khoi T1 - Limit analysis of flaws in pressurized pipes and cylindrical vessels. Part I: Axial defects JF - Engineering Fracture Mechanics. 74 (2007), H. 3 Y1 - 2007 SN - 0013-7944 SP - 431 EP - 450 ER - TY - JOUR A1 - Vant, Christianne A1 - Staat, Manfred A1 - Baroud, Gamal T1 - Percutaneous Vertebroplasty: A Review of Two Intraoperative Complications JF - Bioengineering in Cell and Tissue Research / Artmann, Gerhard M. ; Chien, Shu (Eds.) Y1 - 2008 SN - 978-3-540-75408-4 SP - 527 EP - 539 PB - Springer CY - Berlin ER - TY - JOUR A1 - Vu, Duc Khoi A1 - Staat, Manfred T1 - Shakedown analysis of structures made of materials with temperature-dependent yield stress JF - International Journal of Solids and Structures. 44 (2007), H. 13 Y1 - 2007 SN - 0020-7683 SP - 4524 EP - 4540 ER - TY - CHAP A1 - Knott, Thomas C. A1 - Sofronia, Raluca E. A1 - Gerressen, Marcus A1 - Law, Yuen A1 - Davidescu, Arjana A1 - Savii, George G. A1 - Gatzweiler, Karl-Heinz A1 - Staat, Manfred A1 - Kuhlen, Torsten W. T1 - Preliminary bone sawing model for a virtual reality-based training simulator of bilateral sagittal split osteotomy T2 - Biomedical simulation : 6th International Symposium, ISBMS 2014, Strasbourg, France, October 16-17, 2014 : proceedings (Lecture notes in computer science : vol. 8789) N2 - Successful bone sawing requires a high level of skill and experience, which could be gained by the use of Virtual Reality-based simulators. A key aspect of these medical simulators is realistic force feedback. The aim of this paper is to model the bone sawing process in order to develop a valid training simulator for the bilateral sagittal split osteotomy, the most often applied corrective surgery in case of a malposition of the mandible. Bone samples from a human cadaveric mandible were tested using a designed experimental system. Image processing and statistical analysis were used for the selection of four models for the bone sawing process. The results revealed a polynomial dependency between the material removal rate and the applied force. Differences between the three segments of the osteotomy line and between the cortical and cancellous bone were highlighted. KW - Bone sawing KW - virtual reality KW - training simulator Y1 - 2014 SN - 978-3-319-12057-7 (Online) SN - 978-3-319-12056-0 (Print) U6 - https://doi.org/10.1007/978-3-319-12057-7_1 SP - 1 EP - 10 PB - Springer CY - Cham 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 - Doorschodt, B. M. A1 - Schreinemachers, M. C. J. M. A1 - Behbahani, Mehdi A1 - Florquin, S. A1 - Weis, J. A1 - Staat, Manfred A1 - Tolba, R. H. T1 - Hypothermic machine perfusion of kidney grafts: which pressure is preferred JF - Annals of Biomedical Engineering. 39 (2011), H. 3 Y1 - 2011 SN - 1573-9686 SP - 1051 EP - 1059 PB - Springer CY - Berlin ER - TY - JOUR A1 - Digel, Ilya A1 - Zerlin, Kay A1 - Temiz Artmann, Aysegül A1 - Engels, S. T1 - Protein dynamics in thermosensation JF - Regenerative medicine. 2 (2007), H. 5 Y1 - 2007 SN - 1746-0751 N1 - Proceedings of the 3rd World Congress on Regenerative Medicine. October 18-20, 2007. Leipzig, Germany SP - 533 EP - 533 ER - TY - JOUR A1 - Bhattarai, Aroj A1 - Staat, Manfred T1 - Modelling of Soft Connective Tissues to Investigate Female Pelvic Floor Dysfunctions JF - Computational and Mathematical Methods in Medicine N2 - After menopause, decreased levels of estrogen and progesterone remodel the collagen of the soft tissues thereby reducing their stiffness. Stress urinary incontinence is associated with involuntary urine leakage due to pathological movement of the pelvic organs resulting from lax suspension system, fasciae, and ligaments. This study compares the changes in the orientation and position of the female pelvic organs due to weakened fasciae, ligaments, and their combined laxity. A mixture theory weighted by respective volume fraction of elastin-collagen fibre compound (5%), adipose tissue (85%), and smooth muscle (5%) is adopted to characterize the mechanical behaviour of the fascia. The load carrying response (other than the functional response to the pelvic organs) of each fascia component, pelvic organs, muscles, and ligaments are assumed to be isotropic, hyperelastic, and incompressible. Finite element simulations are conducted during Valsalva manoeuvre with weakened tissues modelled by reduced tissue stiffness. A significant dislocation of the urethrovesical junction is observed due to weakness of the fascia (13.89 mm) compared to the ligaments (5.47 mm). The dynamics of the pelvic floor observed in this study during Valsalva manoeuvre is associated with urethral-bladder hypermobility, greater levator plate angulation, and positive Q-tip test which are observed in incontinent females. Y1 - 2018 U6 - https://doi.org/10.1155/2018/9518076 SN - 1748-6718 VL - 2018 IS - Article ID 9518076 SP - 1 EP - 16 PB - Hindawi CY - New York, NY ER -