TY - JOUR A1 - Scholz, Christina A1 - Romagnoli, Daniele A1 - Dachwald, Bernd A1 - Theil, Stephan T1 - Performance analysis of an attitude control system for solar sails using sliding masses JF - Advances in Space Research Y1 - 2011 SN - 0273-1177 VL - 48 IS - 11 SP - 1822 EP - 1835 PB - Elsevier CY - Amsterdam ER - TY - CHAP A1 - Schoutetens, Frederic A1 - Dachwald, Bernd A1 - Heiligers, Jeannette T1 - Optimisation of photon-sail trajectories in the alpha-centauri system using evolutionary neurocontrol T2 - 8th ICATT (International Conference on Astrodynamics Tools and Techniques) 23 - 25 June 2021, Virtual N2 - With the increased interest for interstellar exploration after the discovery of exoplanets and the proposal by Breakthrough Starshot, this paper investigates the optimisation of photon-sail trajectories in Alpha Centauri. The prime objective is to find the optimal steering strategy for a photonic sail to get captured around one of the stars after a minimum-time transfer from Earth. By extending the idea of the Breakthrough Starshot project with a deceleration phase upon arrival, the mission’s scientific yield will be increased. As a secondary objective, transfer trajectories between the stars and orbit-raising manoeuvres to explore the habitable zones of the stars are investigated. All trajectories are optimised for minimum time of flight using the trajectory optimisation software InTrance. Depending on the sail technology, interstellar travel times of 77.6-18,790 years can be achieved, which presents an average improvement of 30% with respect to previous work. Still, significant technological development is required to reach and be captured in the Alpha-Centauri system in less than a century. Therefore, a fly-through mission arguably remains the only option for a first exploratory mission to Alpha Centauri, but the enticing results obtained in this work provide perspective for future long-residence missions to our closest neighbouring star system. Y1 - 2021 N1 - 8th ICATT (International Conference on Astrodynamics Tools and Techniques) 23 - 25 June 2021, Virtual SP - 1 EP - 15 ER - TY - CHAP A1 - Seboldt, Wolfgang A1 - Blome, Hans-Joachim A1 - Dachwald, Bernd A1 - Richter, Lutz T1 - Proposal for an integrated European space exploration strategy T2 - 55th International Astronautical Congress of the International Astronautical Federation, the International Academy of Astronautics, and the International Institute of Space Law N2 - Recently, in his vision for space exploration, US president Bush announced to extend human presence across the solar system, starting with a human return to the Moon as early as 2015 in preparation for human exploration of Mars and other destinations. In Europe, an exploration program, termed AURORA, was established by ESA in 2001 – funded on a voluntary basis by ESA member states – with a clear focus on Mars and the ultimate goal of landing humans on Mars around 2030 in international cooperation. In 2003, a Human Spaceflight Vision Group was appointed by ESA with the task to develop a vision for the role of human spaceflight during the next quarter of the century. The resulting vision focused on a European-led lunar exploration initiative as part of a multi-decade, international effort to strengthen European identity and economy. After a review of the situation in Europe concerning space exploration, the paper outlines an approach for a consistent positioning of exploration within the existing European space programs, identifies destinations, and develops corresponding scenarios for an integrated strategy, starting with robotic missions to the Moon, Mars, and near-Earth asteroids. The interests of the European planetary in-situ science community, which recently met at DLR Cologne, are considered. Potential robotic lunar missions comprise polar landings to search for frozen volatiles and a sample return. For Mars, the implementation of a modest robotic landing mission in 2009 to demonstrate the capability for landing and prepare more ambitious and complex missions is discussed. For near-Earth asteroid exploration, a low-cost in-situ technology demonstration mission could yield important results. All proposed scenarios offer excellent science and could therefore create synergies between ESA’s mandatory and optional programs in the area of planetary science and exploration. The paper intents to stimulate the European discussion on space exploration and reflects the personal view of the authors. Y1 - 2004 N1 - 55th International Astronautical Congress 2004 - Vancouver, Canada SP - 1 EP - 10 ER - TY - CHAP A1 - Seboldt, Wolfgang A1 - Dachwald, Bernd T1 - Solar sails for near-term advanced scientific deep space missions T2 - Proceedings of the 8th International Workshop on Combustion and Propulsion N2 - Solar sails are propelled in space by reflecting solar photons off large mirroring surfaces, thereby transforming the momentum of the photons into a propulsive force. This innovative concept for low-thrust space propulsion works without any propellant and thus provides a wide range of opportunities for highenergy low-cost missions. Offering an efficient way of propulsion, solar sailcraft could close a gap in transportation options for highly demanding exploration missions within our solar system and even beyond. On December 17th, 1999, a significant step was made towards the realization of this technology: a lightweight solar sail structure with an area of 20 m × 20 m was successfully deployed on ground in a large facility at the German Aerospace Center (DLR) at Cologne. The deployment from a package of 60 cm × 60 cm × 65 cm with a total mass of less than 35 kg was achieved using four extremely light-weight carbon fiber reinforced plastics (CFRP) booms with a specific mass of 100 g/m. The paper briefly reviews the basic principles of solar sails as well as the technical concept and its realization in the ground demonstration experiment, performed in close cooperation between DLR and ESA. Next possible steps are outlined. They could comprise the in-orbit demonstration of the sail deployment on the upper stage of a low-cost rocket and the verification of the propulsion concept by an autonomous and free flying solar sail in the frame of a scientific mission. It is expected that the present design could be extended to sail sizes of about (40 m)2 up to even (70 m)2 without significant mass penalty. With these areas, the maximum achievable thrust at 1 AU would range between 10 and 40 mN – comparable to some electric thrusters. Such prototype sails with a mass between 50 and 150 kg plus a micro-spacecraft of 50 to 250 kg would have a maximum acceleration in the order of 0.1 mm/s2 at 1 AU, corresponding to a maximum ∆V-capability of about 3 km/s per year. Two near/medium-term mission examples to a near-Earth asteroid (NEA) will be discussed: a rendezvous mission and a sample return mission. KW - solar sail KW - low-thrust KW - near-Earth asteroid KW - sample return KW - solar system Y1 - 2003 N1 - Proceedings of the 8th International Workshop on Combustion and Propulsion. Pozzuoli, Italy, 16 - 21 June 2002. ER - TY - CHAP A1 - Seefeldt, Patric A1 - Bauer, Waldemar A1 - Dachwald, Bernd A1 - Grundmann, Jan Thimo A1 - Straubel, Marco A1 - Sznajder, Maciej A1 - Tóth, Norbert A1 - Zander, Martin E. T1 - Large lightweight deployable structures for planetary defence: solar sail propulsion, solar concentrator payloads, large-scale photovoltaic power T2 - 4th IAA Planetary Defense Conference - PDC 2015, 13-17 April 2015, Frascati, Roma, Italy Y1 - 2015 N1 - IAA-PDC-15-P-20 ER - TY - JOUR A1 - Seefeldt, Patric A1 - Dachwald, Bernd T1 - Temperature increase on folded solar sail membranes JF - Advances in Space Research Y1 - 2021 U6 - http://dx.doi.org/10.1016/j.asr.2020.09.026 SN - 0273-1177 VL - 67 IS - 9 SP - 2688 EP - 2695 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Seidova, Seid-Fatima A1 - Kotliar, Konstantin A1 - Foerger, Frauke A1 - Klopfer, Matthias A1 - Lanzl, Ines T1 - Functional retinal changes in Gaucher disease JF - Documenta Ophthalmologica Y1 - 2009 SN - 1573-2622 VL - 118 IS - 2 SP - 151 EP - 154 PB - Springer CY - Berlin ER - TY - THES A1 - Seifarth, Volker T1 - Ureteral tissue engineering : development of a bioreactor system and subsequent characterization of the generated biohybrids Y1 - 2015 N1 - Duisburg, Essen, Universität Duisburg-Essen, Diss., 2015 PB - Universitätsbibliothek Duisburg-Essen CY - Duisburg ; Essen ER - TY - JOUR A1 - Seifarth, Volker A1 - Goßmann, Matthias A1 - Grosse, J. O. A1 - Becker, C. A1 - Heschel, I. A1 - Artmann, Gerhard A1 - Temiz Artmann, Aysegül T1 - Development of a Bioreactor to Culture Tissue Engineered Ureters Based on the Application of Tubular OPTIMAIX 3D Scaffolds JF - Urologia Internationalis Y1 - 2015 U6 - http://dx.doi.org/10.1159/000368419 SN - 0042-1138 VL - 2015 IS - 95 SP - 106 EP - 113 PB - Karger CY - Basel ER - TY - JOUR A1 - Seifarth, Volker A1 - Grosse, Joachim O. A1 - Grossmann, Matthias A1 - Janke, Heinz Peter A1 - Arndt, Patrick A1 - Koch, Sabine A1 - Epple, Matthias A1 - Artmann, Gerhard A1 - Temiz Artmann, Aysegül T1 - Mechanical induction of bi-directional orientation of primary porcine bladder smooth muscle cells in tubular fibrin-poly(vinylidene fluoride) scaffolds for ureteral and urethral repair using cyclic and focal balloon catheter stimulation JF - Journal of Biomaterials Applications Y1 - 2017 U6 - http://dx.doi.org/10.1177/0885328217723178 SN - 1530-8022 VL - 32 IS - 3 SP - 321 EP - 330 PB - Sage CY - London ER - TY - JOUR A1 - Seifarth, Volker A1 - Schehl, D. A1 - Linder, Peter A1 - Gossmann, Matthias A1 - Digel, Ilya A1 - Artmann, Gerhard A1 - Porst, Dariusz A1 - Preiß, C. A1 - Kayser, Peter A1 - Pack, O. A1 - Temiz Artmann, Aysegül T1 - Ureplace: development of a bioreactor for in vitro culturing of cell seeded tubular vessels on collagen scaffolds N2 - The demand of replacements for inoperable organs exceeds the amount of available organ transplants. Therefore, tissue engineering developed as a multidisciplinary field of research for autologous in-vitro organs. Such three dimensional tissue constructs request the application of a bioreactor. The UREPLACE bioreactor is used to grow cells on tubular collagen scaffolds OPTIMAIX Sponge 1 with a maximal length of 7 cm, in order to culture in vitro an adequate ureter replacement. With a rotating unit, (urothelial) cells can be placed homogeneously on the inner scaffold surface. Furthermore, a stimulation is combined with this bioreactor resulting in an orientation of muscle cells. These culturing methods request a precise control of several parameters and actuators. A combination of a LabBox and the suitable software LabVision is used to set and conduct parameters like rotation angles, velocities, pressures and other important cell culture values. The bioreactor was tested waterproof successfully. Furthermore, the temperature controlling was adjusted to 37 °C and the CO2 - concentration regulated to 5 %. Additionally, the pH step responses of several substances showed a perfect functioning of the designed flow chamber. All used software was tested and remained stable for several days. KW - Tissue Engineering KW - Bioreaktor KW - Organkultur KW - Harnleiter Y1 - 2011 ER - TY - JOUR A1 - Seynnes, O. R. A1 - Bojsen-Moller, J. A1 - Albracht, Kirsten A1 - Arndt, A. A1 - Cronin, N. J. A1 - Finni, T. A1 - Magnusson, S. P. T1 - Ultrasound-based testing of tendon mechanical properties: a critical evaluation JF - Journal of Applied Physiology Y1 - 2015 U6 - http://dx.doi.org/10.1152/japplphysiol.00849.2014 SN - 8750-7587 VL - 118 IS - 2 SP - 133 EP - 141 ER - TY - CHAP A1 - Sherelkhan, Dinara A1 - Alibekova, Alina ED - Digel, Ilya ED - Staat, Manfred ED - Trzewik, Jürgen ED - Sielemann, Stefanie ED - Erni, Daniel ED - Zylka, Waldemar T1 - EEM spectroscopy characterization of humic substances of biomedical importance T2 - 4th YRA MedTech Symposium 2024 : February 1 / 2024 / FH Aachen N2 - Humic substances possess distinctive chemical features enabling their use in many advanced applications, including biomedical fields. No chemicals in nature have the same combination of specific chemical and biological properties as humic substances. Traditional medicine and modern research have demonstrated that humic substances from different sources possess immunomodulatory and anti-inflammatory properties, which makes them suitable for the prevention and treatment of chronic dermatoses, allergic rhinitis, atopic dermatitis, and other conditions characterized by inflammatory and allergic responses [1-4]. The use of humic compounds as agentswith antifungal and antiviral properties shows great potential [5-7]. Y1 - 2024 SN - 978-3-940402-65-3 U6 - http://dx.doi.org/10.17185/duepublico/81475 SP - 31 EP - 32 PB - Universität Duisburg-Essen CY - Duisburg ER - TY - JOUR A1 - Smith, Wayne A1 - Kotliar, Konstantin A1 - Lammertyn, Leandi A1 - Ramoshaba, Nthai E. A1 - Vilser, Walthard A1 - Huisman, Hugo W. A1 - Schutte, Aletta E. T1 - Retinal vessel caliber and caliber responses in true normotensive black and white adults: The African-PREDICT study JF - Microvascular Research N2 - Purpose Globally, a detrimental shift in cardiovascular disease risk factors and a higher mortality level are reported in some black populations. The retinal microvasculature provides early insight into the pathogenesis of systemic vascular diseases, but it is unclear whether retinal vessel calibers and acute retinal vessel functional responses differ between young healthy black and white adults. Methods We included 112 black and 143 white healthy normotensive adults (20–30 years). Retinal vessel calibers (central retinal artery and vein equivalent (CRAE and CRVE)) were calculated from retinal images and vessel caliber responses to flicker light induced provocation (FLIP) were determined. Additionally, ambulatory blood pressure (BP), anthropometry and blood samples were collected. Results The groups displayed similar 24 h BP profiles and anthropometry (all p > .24). Black participants demonstrated a smaller CRAE (158 ± 11 vs. 164 ± 11 MU, p < .001) compared to the white group, whereas CRVE was similar (p = .57). In response to FLIP, artery maximal dilation was greater in the black vs. white group (5.6 ± 2.1 vs. 3.3 ± 1.8%; p < .001). Conclusions Already at a young age, healthy black adults showed narrower retinal arteries relative to the white population. Follow-up studies are underway to show if this will be related to increased risk for hypertension development. The reason for the larger vessel dilation responses to FLIP in the black population is unclear and warrants further investigation. Y1 - 2020 U6 - http://dx.doi.org/10.1016/j.mvr.2019.103937 SN - 0026-2862 VL - 128 IS - Article 103937 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Spietz, Peter A1 - Spröwitz, Tom A1 - Seefeldt, Patric A1 - Grundmann, Jan Thimo A1 - Jahnke, Rico A1 - Mikschl, Tobias A1 - Mikulz, Eugen A1 - Montenegro, Sergio A1 - Reershemius, Siebo A1 - Renger, Thomas A1 - Ruffer, Michael A1 - Sasaki, Kaname A1 - Sznajder, Maciej A1 - Tóth, Norbert A1 - Ceriotti, Matteo A1 - Dachwald, Bernd A1 - Macdonald, Malcolm A1 - McInnes, Colin A1 - Seboldt, Wolfgang A1 - Quantius, Dominik A1 - Bauer, Waldemar A1 - Wiedemann, Carsten A1 - Grimm, Christian D. A1 - Hercik, David A1 - Ho, Tra-Mi A1 - Lange, Caroline A1 - Schmitz, Nicole T1 - Paths not taken – The Gossamer roadmap’s other options JF - Advances in Space Research KW - Solar sail KW - Small spacecraft KW - DLR-ESTEC GOSSAMER roadmap for solar sailing KW - GOSSAMER-1 Y1 - 2021 U6 - http://dx.doi.org/10.1016/j.asr.2021.01.044 SN - 0273-1177 VL - 67 IS - 9 SP - 2912 EP - 2956 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Sponagel, Stefan A1 - Baroud, G. A1 - Falk, R. A1 - Crookshank, M. T1 - Experimental and theoretical investigation of directional permeability of human vertebral cancellous bone for cement infiltration. G. Baroud, R. Falk, M. Crookshank, S. Sponagel, T. Steffen JF - Journal of Biomechanics. 37 (2004), H. 2 Y1 - 2004 SN - 0021-9290 SP - 189 EP - 196 ER - TY - JOUR A1 - Sponagel, Stefan A1 - Baroud, G. A1 - Falk, R. A1 - Crookshank, M. T1 - Corrigendum to “Experimental and theoretical investigation of directional permeability of human vertebral cancellous bone for cement infiltration”. Baroud, G.; Falk, R.; Crookshank, M.; Sponagel, S.; Steffen, T. JF - Journal of Biomechanics. 37 (2004), H. 2 Y1 - 2004 SN - 0021-9290 SP - 1802 ER - TY - JOUR A1 - Sponagel, Stefan A1 - Baroud, G. A1 - Steffen, T. A1 - Wu, J. T1 - Parameter identification for cement infiltration of osteoporotic bone JF - Poromechanics II : Proceedings of the Second Biot Conference on Poromechanics Grenoble, France 26 - 28 August 2002 / ed. by J.-L. Auriault ... Y1 - 2002 SN - 90-5809-394-8 SP - 55 EP - 58 PB - Balkema CY - Lisse [u.a.] ER - TY - 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 - Some Achievements of the European Project LISA for FEM Based Limit and Shakedown Analysis JF - Computational mechanics : developments and applications, 2002 : presented at the 2002 ASME Pressure Vessels and Piping Conference, Vancouver, British Columbia, Canada, August 5 - 9. / Badie, N. [ed] Y1 - 2002 SN - 0791846520 N1 - Serie PVP ; vol. 441. SP - 177 EP - 185 PB - American Society of Mechanical Engineers CY - New York ER - TY - JOUR A1 - Staat, Manfred T1 - Plastic collapse analysis of longitudinally flawed pipes and vessels JF - Nuclear Engineering and Design. 234 (2004), H. 1-3 Y1 - 2004 SN - 0029-5493 SP - 25 EP - 43 ER - TY - JOUR A1 - Staat, Manfred T1 - Local and global collapse pressure of longitudinally flawed pipes and cylindrical vessels JF - International Journal of Pressure Vessels and Piping. 82 (2005), H. 3 Y1 - 2005 SN - 0308-0161 SP - 217 EP - 225 ER - TY - JOUR A1 - Staat, Manfred T1 - Limit and shakedown analysis under uncertainty JF - International journal of computational methods : IJCM Y1 - 2013 SN - 0219-8762 SP - Publ. online PB - World Scientific Publishing CY - Singapore ER - TY - JOUR A1 - Staat, Manfred T1 - Plastic collapse analysis of longitudinally flawed pipes and vessels N2 - Improved collapse loads of thick-walled, crack containing pipes and vessels are suggested. Very deep cracks have a residual strength which is better modelled by a global limit load. In all burst tests, the ductility of pressure vessel steels was sufficiently high whereby the burst pressure could be predicted by limit analysis with no need to apply fracture mechanics. The relative prognosis error increases however, for long and deep defects due to uncertainties of geometry and strength data. KW - Druckbehälter KW - Stahl KW - Druckbelastung KW - Druckbeanspruchung KW - Rohr KW - Rohrbruch KW - Druckbehälter KW - Stahl KW - Druckbelastung KW - Druckbeanspruchung KW - Rohrbruch KW - Fehlerstellen KW - pipes KW - vessels KW - load limit KW - burst tests KW - burst pressure KW - flaw Y1 - 2004 ER - TY - JOUR A1 - Staat, Manfred T1 - Local and global collapse pressure of longitudinally flawed pipes and cylindrical vessels N2 - Limit loads can be calculated with the finite element method (FEM) for any component, defect geometry, and loading. FEM suggests that published long crack limit formulae for axial defects under-estimate the burst pressure for internal surface defects in thick pipes while limit loads are not conservative for deep cracks and for pressure loaded crack-faces. Very deep cracks have a residual strength, which is modelled by a global collapse load. These observations are combined to derive new analytical local and global collapse loads. The global collapse loads are close to FEM limit analyses for all crack dimensions. KW - Finite-Elemente-Methode KW - Grenzwertberechnung KW - Axialbelastung KW - FEM KW - Grenzwertberechnung KW - Axialbelastung KW - Traglastanalyse KW - Limit analysis KW - Global and local collapse KW - Axially cracked pipe KW - Pressure loaded crack-face Y1 - 2005 ER - TY - JOUR A1 - Staat, Manfred T1 - Direct finite element route for design-by-analysis of pressure components N2 - In the new European standard for unfired pressure vessels, EN 13445-3, there are two approaches for carrying out a Design-by-Analysis that cover both the stress categorization method (Annex C) and the direct route method (Annex B) for a check against global plastic deformation and against progressive plastic deformation. This paper presents the direct route in the language of limit and shakedown analysis. This approach leads to an optimization problem. Its solution with Finite Element Analysis is demonstrated for mechanical and thermal actions. One observation from the examples is that the so-called 3f (3Sm) criterion fails to be a reliable check against progressive plastic deformation. Precise conditions are given, which greatly restrict the applicability of the 3f criterion. KW - Einspielen KW - Plastizität KW - Deformation KW - Analytischer Zulaessigkeitsnachweis KW - Einspiel-Analyse KW - fortschreitende plastische Deformation KW - alternierend Verformbarkeit KW - Einspiel-Kriterium KW - Design-by-analysis KW - Shakedown analysis KW - Progressive plastic deformation KW - Alternating plasticity KW - Shakedown criterion Y1 - 2005 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 - CHAP A1 - Staat, Manfred T1 - Design by Analysis of Pressure Components by non-linear Optimization N2 - This paper presents the direct route to Design by Analysis (DBA) of the new European pressure vessel standard in the language of limit and shakedown analysis (LISA). This approach leads to an optimization problem. Its solution with Finite Element Analysis is demonstrated for some examples from the DBA-Manual. One observation from the examples is, that the optimisation approach gives reliable and close lower bound solutions leading to simple and optimised design decision. KW - Analytischer Zulaessigkeitsnachweis KW - FEM KW - Einspiel-Analyse KW - design-by-analysis KW - finite element analysis KW - limit and shakedown analysis Y1 - 2003 ER - TY - GEN A1 - Staat, Manfred T1 - Engineering Mechanics. Lecture Notes. 2nd edition, translation of the 3rd corrected and extended German edition of "Technische Mechanik" N2 - English translation of the corrected lectures notes of Sebastian Krämer. Contents 0 Introduction to Mechanics 1 Statics of Rigid Bodies 2 Elastostatics (Strength of Materials) 3 Kinematics 4 Kinetics Literature KW - Technische Mechanik KW - Mechanics KW - Statics KW - Elastostatics KW - Kinematics KW - Kinetics Y1 - 2006 ER - TY - CHAP A1 - Staat, Manfred T1 - Problems and chances for probabilistic fracture mechanics in the analysis of steel pressure boundary reliability. - Überarb. Ausg. N2 - In: Technical feasibility and reliability of passive safety systems for nuclear power plants. Proceedings of an Advisory Group Meeting held in Jülich, 21-24 November 1994. - Vienna , 1996. - Seite: 43 - 55 IAEA-TECDOC-920 Abstract: It is shown that the difficulty for probabilistic fracture mechanics (PFM) is the general problem of the high reliability of a small population. There is no way around the problem as yet. Therefore what PFM can contribute to the reliability of steel pressure boundaries is demon­strated with the example of a typical reactor pressure vessel and critically discussed. Although no method is distinguishable that could give exact failure probabilities, PFM has several addi­tional chances. Upper limits for failure probability may be obtained together with trends for design and operating conditions. Further, PFM can identify the most sensitive parameters, improved control of which would increase reliability. Thus PFM should play a vital role in the analysis of steel pressure boundaries despite all shortcomings. KW - Bruchmechanik KW - probabilistic fracture mechanics KW - PFM Y1 - 2006 ER - TY - JOUR A1 - Staat, Manfred T1 - Limit and shakedown analysis under uncertainty JF - Tap chi Khoa hoc & ung dung - Dai hoc Ton Duc Thang Y1 - 2012 N1 - = Journal of Applied Sciences - Ton Duc Thang University VL - 19 SP - 45 EP - 47 ER - TY - JOUR A1 - Staat, Manfred T1 - An extension strain type Mohr–Coulomb criterion JF - Rock mechanics and rock engineering N2 - Extension fractures are typical for the deformation under low or no confining pressure. They can be explained by a phenomenological extension strain failure criterion. In the past, a simple empirical criterion for fracture initiation in brittle rock has been developed. In this article, it is shown that the simple extension strain criterion makes unrealistic strength predictions in biaxial compression and tension. To overcome this major limitation, a new extension strain criterion is proposed by adding a weighted principal shear component to the simple criterion. The shear weight is chosen, such that the enriched extension strain criterion represents the same failure surface as the Mohr–Coulomb (MC) criterion. Thus, the MC criterion has been derived as an extension strain criterion predicting extension failure modes, which are unexpected in the classical understanding of the failure of cohesive-frictional materials. In progressive damage of rock, the most likely fracture direction is orthogonal to the maximum extension strain leading to dilatancy. The enriched extension strain criterion is proposed as a threshold surface for crack initiation CI and crack damage CD and as a failure surface at peak stress CP. Different from compressive loading, tensile loading requires only a limited number of critical cracks to cause failure. Therefore, for tensile stresses, the failure criteria must be modified somehow, possibly by a cut-off corresponding to the CI stress. Examples show that the enriched extension strain criterion predicts much lower volumes of damaged rock mass compared to the simple extension strain criterion. Y1 - 2021 U6 - http://dx.doi.org/10.1007/s00603-021-02608-7 SN - 1434-453X N1 - Corresponding author: Manfred Staat VL - 54 IS - 12 SP - 6207 EP - 6233 PB - Springer Nature CY - Cham ER - TY - JOUR A1 - Staat, Manfred A1 - Baroud, G. A1 - Topcu, M. A1 - Sponagel, Stefan T1 - Soft Materials in Technology and Biology – Characteristics, Properties, and Parameter Identification JF - Bioengineering in Cell and Tissue Research / Artmann, Gerhard M. ; Chien, Shu (Eds.) Y1 - 2008 SN - 978-3-540-75408-4 SP - 253 EP - 315 PB - Springer CY - Berlin ER - TY - GEN A1 - Staat, Manfred A1 - Barry, Steve T1 - Continuum Mechanics with an Introduction to the Finite Element Method / Steve Barry; Manfred Staat. With extensions by Manfred Staat. N2 - Contents: 1 Introduction 2 One Dimensional Continuum Mechanics 3 Tensors 4 Three Dimensional Stress and Strain 5 Conservation Laws 6 Contiunuum Modelling 7 Plain Problems 8 Questions 9 Reference Information KW - Technische Mechanik KW - Finite-Elemente-Methode Y1 - 2006 ER - TY - BOOK A1 - Staat, Manfred A1 - Digel, Ilya A1 - Trzewik, Jürgen A1 - Sielemann, Stefanie A1 - Erni, Daniel A1 - Zylka, Waldemar T1 - Symposium Proceedings; 4th YRA MedTech Symposium 2024 : February 1 / 2024 / FH Aachen Y1 - 2024 SN - 978-3-940402-65-3 U6 - http://dx.doi.org/10.17185/duepublico/81475 PB - Universität Duisburg-Essen CY - Duisburg ER - TY - CHAP A1 - Staat, Manfred A1 - Duong, Minh Tuan T1 - Smoothed Finite Element Methods for Nonlinear Solid Mechanics Problems: 2D and 3D Case Studies T2 - Proceedings of the National Science and Technology Conference on Mechanical - Transportation Engineering (NSCMET 2016), 13th October 2016, Hanoi, Vietnam, Vol.2 N2 - The Smoothed Finite Element Method (SFEM) is presented as an edge-based and a facebased techniques for 2D and 3D boundary value problems, respectively. SFEMs avoid shortcomings of the standard Finite Element Method (FEM) with lower order elements such as overly stiff behavior, poor stress solution, and locking effects. Based on the idea of averaging spatially the standard strain field of the FEM over so-called smoothing domains SFEM calculates the stiffness matrix for the same number of degrees of freedom (DOFs) as those of the FEM. However, the SFEMs significantly improve accuracy and convergence even for distorted meshes and/or nearly incompressible materials. Numerical results of the SFEMs for a cardiac tissue membrane (thin plate inflation) and an artery (tension of 3D tube) show clearly their advantageous properties in improving accuracy particularly for the distorted meshes and avoiding shear locking effects. Y1 - 2016 SP - 440 EP - 445 ER - TY - BOOK A1 - Staat, Manfred A1 - Erni, Daniel T1 - Symposium Proceedings; 3rd YRA MedTech Symposium 2019: May 24 / 2019 / FH Aachen Y1 - 2019 SN - 978-3-940402-22-6 U6 - http://dx.doi.org/10.17185/duepublico/48750 PB - Universität Duisburg-Essen CY - Duisburg ER - TY - JOUR A1 - Staat, Manfred A1 - Heitzer, M. T1 - Limit and Shakedown Analysis with Uncertain Data JF - Stochastic optimization techniques : numerical methods and technical applications / Marti, K. [ed] Y1 - 2002 SN - 3-540-42889-5 SP - 241 EP - 254 PB - Springer CY - Heidelberg ER - TY - JOUR A1 - Staat, Manfred A1 - Heitzer, M. T1 - Probabilistic limit and shakedown problems JF - Numerical Methods for Limit and Shakedown Analysis. Deterministic and Probabilistic Approach. NIC Series Vol. 15 / Ed. by Staat, M; Heitzer, M. Y1 - 2003 SN - 3-00-010001-6 SP - 217 EP - 268 PB - John von Neumann Institute for Computing (NIC) CY - Jülich ER - TY - CHAP A1 - Staat, Manfred A1 - Heitzer, M. T1 - Basis reduction technique for limit and shakedown problems T2 - Numerical Methods for Limit and Shakedown Analysis. Deterministic and Probabilistic Approach. NIC Series Vol. 15 / Ed. by Staat, M.; Heitzer, M. Y1 - 2003 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:0001-2018112115 SN - 3-00-010001-6 SP - 1 EP - 55 PB - John von Neumann Institute for Computing (NIC) CY - Jülich ER - TY - JOUR A1 - Staat, Manfred A1 - Heitzer, M. A1 - Lang, H. A1 - Wirtz, K. T1 - Direct Finite Element Route for Design-by-Analysis of Pressure Components JF - International Journal of Pressure Vessels and Piping. 82 (2005), H. 1 Y1 - 2005 SN - 0308-0161 SP - 61 EP - 67 ER - TY - JOUR A1 - Staat, Manfred A1 - Heitzer, M. A1 - Reiners, H. A1 - Schubert, F. T1 - Shakedown and ratchetting under tension–torsion loadings: analysis and experiments JF - Nuclear Engineering and Design. 225 (2003), H. 1 Y1 - 2003 SN - 0029-5493 SP - 11 EP - 26 ER - TY - CHAP A1 - Staat, Manfred A1 - Heitzer, Michael T1 - The restricted influence of kinematic hardening on shakedown loads N2 - Structural design analyses are conducted with the aim of verifying the exclusion of ratcheting. To this end it is important to make a clear distinction between the shakedown range and the ratcheting range. In cyclic plasticity more sophisticated hardening models have been suggested in order to model the strain evolution observed in ratcheting experiments. The hardening models used in shakedown analysis are comparatively simple. It is shown that shakedown analysis can make quite stable predictions of admissible load ranges despite the simplicity of the underlying hardening models. A linear and a nonlinear kinematic hardening model of two-surface plasticity are compared in material shakedown analysis. Both give identical or similar shakedown ranges. Structural shakedown analyses show that the loading may have a more pronounced effect than the hardening model. KW - Biomedizinische Technik KW - Einspielen KW - Shakedown KW - Ratcheting KW - Bruchmechanik KW - shakedown KW - material shakedown KW - linear kinematic hardening KW - nonlinear kinematic hardening KW - ratchetting Y1 - 2002 ER - TY - CHAP A1 - Staat, Manfred A1 - Heitzer, Michael ED - Staat, Manfred ED - Heitzer, Michael T1 - Probabilistic limit and shakedown problems T2 - Numerical methods for limit and shakedown analysis. Deterministic and probabilistic problems Y1 - 2003 SN - 3-00-010001-6 N1 - NIC Series VL - 15 SP - 217 EP - 268 PB - John von Neumann Institute for Computing (NIC) CY - Jülich ER - TY - BOOK A1 - Staat, Manfred A1 - Heitzer, Michael T1 - Numerical methods for limit and shakedown analysis. Deterministic and probabilistic problems. Y1 - 2003 SN - 3-00-010001-6 N1 - NIC Series Vol. 15 / Ed. by Staat, M; Heitzer, M. PB - John von Neumann Institute for Computing (NIC) CY - Jülich ER - TY - JOUR A1 - Staat, Manfred A1 - Schwartz, M. A1 - Lang, H. A1 - Wirtz, K. A1 - Heitzer, M. T1 - Design by Analysis of Pressure Components by non-linear Optimization JF - The 10th International Conference on Pressure Vessel Technology, July 7-10, 2003, Vienna, Austria, Proceedings ICPVT-10 / Zeman, J. L. [ed] Y1 - 2003 SN - 3950152814 SP - 59 EP - 65 PB - ÖGS, Österreichische Gesellschaft für Schweißtechnik CY - Wien ER - TY - JOUR A1 - Staat, Manfred A1 - Sponagel, Stefan A1 - Nguyen, Nhu Huynh T1 - Experiment and material model for soft tissue materials JF - Constitutive models for rubber VI : proceedings of the sixth European Conference on Constitutive Models for Rubber, Dresden, Germany, 7 - 10 September 2009 / eds. Gert Heinrich ... Y1 - 2010 SN - 978-0-415-56327-7 SP - 465 EP - 470 PB - CRC Press CY - Boca Raton [u.a.] ER - TY - CHAP A1 - Staat, Manfred A1 - Tran, Ngoc Trinh T1 - Strain based brittle failure criteria for rocks T2 - Proceedings of (NACOME2022) The 11th National Conference on Mechanics, Vol. 1. Solid Mechanics, Rock Mechanics, Artificial Intelligence, Teaching and Training, Hanoi, December 2-3, 2022 N2 - When confining pressure is low or absent, extensional fractures are typical, with fractures occurring on unloaded planes in rock. These “paradox” fractures can be explained by a phenomenological extension strain failure criterion. In the past, a simple empirical criterion for fracture initiation in brittle rock has been developed. But this criterion makes unrealistic strength predictions in biaxial compression and tension. A new extension strain criterion overcomes this limitation by adding a weighted principal shear component. The weight is chosen, such that the enriched extension strain criterion represents the same failure surface as the Mohr–Coulomb (MC) criterion. Thus, the MC criterion has been derived as an extension strain criterion predicting failure modes, which are unexpected in the understanding of the failure of cohesive-frictional materials. In progressive damage of rock, the most likely fracture direction is orthogonal to the maximum extension strain. The enriched extension strain criterion is proposed as a threshold surface for crack initiation CI and crack damage CD and as a failure surface at peak P. Examples show that the enriched extension strain criterion predicts much lower volumes of damaged rock mass compared to the simple extension strain criterion. KW - Extension fracture KW - Extension strain criterion KW - Mohr–Coulomb criterion KW - Evolution of damage Y1 - 2023 SN - 978-604-357-084-7 SP - 500 EP - 509 PB - Nha xuat ban Khoa hoc tu nhien va Cong nghe (Verlag Naturwissenschaft und Technik) CY - Hanoi ER - TY - JOUR A1 - Staat, Manfred A1 - Tran, Thanh Ngoc A1 - Kreißig, R. T1 - Load bearing capacity of thin shell structures made of elastoplastic material by direct methods JF - Technische Mechanik. 28 (2008), H. 3-4 Y1 - 2008 SP - 299 EP - 309 ER - TY - CHAP A1 - Staat, Manfred A1 - Tran, Thanh Ngoc A1 - Pham, Phu Tinh T1 - Limit and shakedown reliability analysis by nonlinear programming N2 - 7th International Conference on Reliability of Materials and Structures (RELMAS 2008). June 17 - 20, 2008 ; Saint Petersburg, Russia. pp 354-358. Reprint with corrections in red Introduction Analysis of advanced structures working under extreme heavy loading such as nuclear power plants and piping system should take into account the randomness of loading, geometrical and material parameters. The existing reliability are restricted mostly to the elastic working regime, e.g. allowable local stresses. Development of the limit and shakedown reliability-based analysis and design methods, exploiting potential of the shakedown working regime, is highly needed. In this paper the application of a new algorithm of probabilistic limit and shakedown analysis for shell structures is presented, in which the loading and strength of the material as well as the thickness of the shell are considered as random variables. The reliability analysis problems may be efficiently solved by using a system combining the available FE codes, a deterministic limit and shakedown analysis, and the First and Second Order Reliability Methods (FORM/SORM). Non-linear sensitivity analyses are obtained directly from the solution of the deterministic problem without extra computational costs. KW - Finite-Elemente-Methode KW - Limit analysis KW - Shakedown analysis Y1 - 2008 ER - TY - JOUR A1 - Staat, Manfred A1 - Trenz, Eva A1 - Lohmann, Philipp A1 - Frotscher, Ralf A1 - Klinge, Uwe A1 - Tabaza, Ruth A1 - Kirschner-Hermanns, Ruth T1 - New measurements to compare soft tissue anchoring systems in pelvic floor surgery JF - Journal of Biomedical Materials Research Part B: Applied Biomaterials N2 - Suburethral slings as well as different meshes are widely used treating stress urinary incontinence and prolaps in women. With the development of MiniSlings and special meshes using less alloplastic material anchorage systems become more important to keep devices in place and to put some tension especially on the MiniSlings. To date, there are many different systems of MiniSlings of different companies on the market which differ in the structure of the used meshes and anchors. A new objective measurement method to compare different properties of MiniSling systems (mesh and anchor) is presented in this article. Ballistic gelatine acts as soft tissue surrogate. Significant differences in parameters like pull-out strength of anchors or shrinkage of meshes under loading conditions have been determined. The form and size of the anchors as well as the structural stability of the meshes are decisive for a proper integration. The tested anchorings sytems showed markedly different mechanical function at their respective load bearing capacity. As the stable fixation of the device in tissue is a prerequisite for a permanet reinforcement, the proposed test system permits further optimisation of anchor and mesh devices to improve the success of the surgical treatment Y1 - 2012 U6 - http://dx.doi.org/10.1002/jbm.b.32654 SN - 1552-4981 VL - 100B IS - 4 SP - 924 EP - 933 PB - Wiley CY - Hoboken, NJ ER - TY - JOUR A1 - Staat, Manfred A1 - Vu, Duc Khoi T1 - Limit analysis of flaws in pressurized pipes and cylindrical vessels Part II: Circumferential defects JF - Engineering Fracture Mechanics ; 97(2013), H. 1 N2 - Upper and lower bound theorems of limit analyses have been presented in part I of the paper. Part II starts with the finite element discretization of these theorems and demonstrates how both can be combined in a primal–dual optimization problem. This recently proposed numerical method is used to guide the development of a new class of closed-form limit loads for circumferential defects, which show that only large defects contribute to plastic collapse with a rapid loss of strength with increasing crack sizes. The formulae are compared with primal–dual FEM limit analyses and with burst tests. Even closer predictions are obtained with iterative limit load solutions for the von Mises yield function and for the Tresca yield function. Pressure loading of the faces of interior cracks in thick pipes reduces the collapse load of circumferential defects more than for axial flaws. Axial defects have been treated in part I of the paper. Y1 - 2012 U6 - http://dx.doi.org/10.1016/j.engfracmech.2012.05.017 SN - 0013-7944 VL - 97 SP - 314 EP - 333 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Staat, Manfred A1 - Vu, Duc-Khoi T1 - An Algorithm for Shakedown Analysis for Materials with Temperature Dependent Yield Stress JF - Proceedings in Applied Mathematics and Mechanics (PAMM). 4 (2004), H. 1 Y1 - 2004 SN - 1617-7061 SP - 231 EP - 233 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 - Staat, Manfred A1 - Vu, Khoi Duc T1 - Limit loads of circumferentially flawed pipes and cylindrical vessels under internal pressure JF - International Journal of Pressure Vessels and Piping. 83 (2006), H. 3 Y1 - 2006 SN - 0308-0161 SP - 188 EP - 196 ER - TY - JOUR A1 - Stadler, A. M. A1 - Digel, Ilya A1 - Artmann, Gerhard A1 - Embs, Jan P. A1 - Zaccai, Joe A1 - Büldt, Georg T1 - Hemoglobin Dynamics in Red Blood Cells: Correlation to Body Temperature JF - Biophysical Journal. 95 (2008), H. 11 Y1 - 2008 SN - 1542-0086 SP - 5449 EP - 5461 ER - TY - JOUR A1 - Stadler, Alexander Maximilian A1 - Garvey, Christopher J. A1 - Embs, Jan Peter A1 - Koza, Michael Marek A1 - Unruh, Tobias A1 - Artmann, Gerhard A1 - Zaccai, Guiseppe T1 - Picosecond dynamics in haemoglobin from different species: A quasielastic neutron scattering study JF - Biochimica et biophysica acta (BBA): General Subjects Y1 - 2014 U6 - http://dx.doi.org/10.1016/j.bbagen.2014.06.007 SN - 1872-8006 (E-Journal); 0304-4165 (Print) VL - 1840 IS - 10 SP - 2989 EP - 2999 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Stadler, Andreas M. A1 - Digel, Ilya A1 - Embs, Jan P. A1 - Unruh, Tobias A1 - Tehei, M. A1 - Zaccai, G. A1 - Büldt, G. A1 - Artmann, Gerhard T1 - From powder to solution : Hydration dependence of human hemoglobin dynamics correlated to body temperature JF - Biophysical Journal. 96 (2009), H. 12 Y1 - 2009 SN - 0006-3495 SP - 5073 EP - 5081 PB - Cell Press CY - Cambridge, Mass. ER - TY - JOUR A1 - Stadler, Andreas M. A1 - Embs, Jan P. A1 - Digel, Ilya A1 - Artmann, Gerhard A1 - Unruh, Tobias A1 - Büldt, Georg A1 - Zaccai, Guiseppe T1 - Cytoplasmic water and hydration layer dynamics in human red blood cells JF - Journal of the American Chemical Society. 50 (2008), H. 130 Y1 - 2008 SN - 1520-5126 SP - 16852 EP - 16853 ER - TY - CHAP A1 - Stadler, Andreas M. A1 - Embs, Jan P. A1 - Zerlin, Kay A1 - Digel, Ilya A1 - Artmann, Gerhard A1 - Zaccai, Joe A1 - Büldt, Georg T1 - Temperature transitions of hemoglobin and cytosolic water diffusion in human red blood cells : [poster] N2 - Background Hemoglobin interactions in red blood cells Hemoglobin dynamics in human red blood cells Diffusion of H2O in red blood cells KW - Erythrozyt KW - Hämoglobin KW - cytosolic water diffusion KW - hemoglobin dynamics Y1 - 2007 ER - TY - JOUR A1 - Stadler, Andreas M. A1 - Garvey, G. J. A1 - Bocahut, A. A1 - Sacquin-Mora, S. A1 - Digel, Ilya A1 - Schneider, G. J. A1 - Natali, F. A1 - Artmann, Gerhard A1 - Zaccai, G. T1 - Thermal fluctuations of haemoglobin from different species : adaptation to temperature via conformational dynamics JF - Journal of the Royal Society Interface N2 - Thermodynamic stability, configurational motions and internal forces of haemoglobin (Hb) of three endotherms (platypus, Ornithorhynchus anatinus; domestic chicken, Gallus gallus domesticus and human, Homo sapiens) and an ectotherm (salt water crocodile, Crocodylus porosus) were investigated using circular dichroism, incoherent elastic neutron scattering and coarse-grained Brownian dynamics simulations. The experimental results from Hb solutions revealed a direct correlation between protein resilience, melting temperature and average body temperature of the different species on the 0.1 ns time scale. Molecular forces appeared to be adapted to permit conformational fluctuations with a root mean square displacement close to 1.2 Å at the corresponding average body temperature of the endotherms. Strong forces within crocodile Hb maintain the amplitudes of motion within a narrow limit over the entire temperature range in which the animal lives. In fully hydrated powder samples of human and chicken, Hb mean square displacements and effective force constants on the 1 ns time scale showed no differences over the whole temperature range from 10 to 300 K, in contrast to the solution case. A complementary result of the study, therefore, is that one hydration layer is not sufficient to activate all conformational fluctuations of Hb in the pico- to nanosecond time scale which might be relevant for biological function. Coarse-grained Brownian dynamics simulations permitted to explore residue-specific effects. They indicated that temperature sensing of human and chicken Hb occurs mainly at residues lining internal cavities in the β-subunits. Y1 - 2012 U6 - http://dx.doi.org/10.1098/rsif.2012.0364 SN - 1742-5689 VL - 9 IS - 76 SP - 2845 EP - 2855 PB - The Royal Society CY - London ER - TY - JOUR A1 - Stadler, Andreas M. A1 - Zerlin, Kay A1 - Digel, Ilya A1 - Büldt, Georg A1 - Zaccai, Guiseppe A1 - Artmann, Gerhard T1 - Dynamics and interactions of hemoglobin in red blood cells JF - Tissue Engineering Part A. 14 (2008), H. 5 Y1 - 2008 SN - 1937-3341 N1 - TERMIS EU 2008 Porto Meeting June 22–26, 2008 Porto Congress Center–Alfândega Portugal SP - 724 EP - 724 ER - TY - JOUR A1 - Steinseifer, Ulrich A1 - Kashefi, Ali A1 - Hormes, Marcus A1 - Schoberer, Mark A1 - Orlikowsky, Thorsten A1 - Behbahani, Mehdi A1 - Behr, Marek A1 - Schmitz-Rode, Thomas T1 - Miniaturization of ECMO Systems : Engineering Challenges and Methods JF - Artificial Organs. 33 (2009), H. 5 Y1 - 2009 SN - 1525-1594 N1 - Fifth International Conference on Pediatric Mechanical Circulatory Support Systems and Pediatric Cardiopulmonary Perfusion Abstracts SP - A55 EP - A55 ER - TY - JOUR A1 - Streese, Lukas A1 - Kotliar, Konstantin A1 - Deiseroth, Arne A1 - Infanger, Denis A1 - Gugleta, Konstantin A1 - Schmaderer, Christoph A1 - Hanssen, Henner T1 - Retinal endothelial function in cardiovascular risk patients: A randomized controlled exercise trial JF - Scandinavian Journal of Medicine and Science in Sports N2 - The aim of this study was to investigate, for the first time, the effects of high-intensity interval training (HIIT) on retinal microvascular endothelial function in cardiovascular (CV) risk patients. In the randomized controlled trial, middle-aged and previously sedentary patients with increased CV risk (aged 58 ± 6 years) with ≥ two CV risk factors were randomized into a 12-week HIIT (n = 33) or control group (CG, n = 36) with standard physical activity recommendations. A blinded examiner measured retinal endothelial function by flicker light-induced maximal arteriolar (ADmax) and venular (VDmax) dilatation as well as the area under the arteriolar (AFarea) and venular (VFarea) flicker curve using a retinal vessel analyzer. Standardized assessments of CV risk factors, cardiorespiratory fitness, and retinal endothelial function were performed before and after HIIT. HIIT reduced body mass index, fat mass, and low-density lipoprotein and increased muscle mass and peak oxygen uptake (VO2peak). Both ADmax (pre: 2.7 ± 2.1%, post: 3.0 ± 2.2%, P = .018) and AFarea (pre: 32.6 ± 28.4%*s, post: 37.7 ± 30.6%*s, P = .016) increased after HIIT compared with CG (ADmax, pre: 3.2 ± 1.8%, post: 2.9 ± 1.8%, P = .254; AFarea, pre: 41.6 ± 28.5%*s, post: 37.8 ± 27.0%*s, P = .186). Venular function remained unchanged after HIIT. There was a significant association between ∆-change VO2peak and ∆-changes ADmax and AFarea (P = .026, R² = 0.073; P = .019, R² = 0.081, respectively). 12-weeks of HIIT improved retinal endothelial function in middle-aged patients with increased CV risk independent of the reduction in classical CV risk factors. Exercise has the potential to reverse or at least postpone progression of small vessel disease in older adults with increased CV risk under standard medication. Dynamic retinal vessel analysis seems to be a sensitive tool to detect treatment effects of exercise interventions on retinal microvascular endothelial function in middle-aged individuals with increased CV risk. Y1 - 2020 U6 - http://dx.doi.org/10.1111/sms.13560 SN - 1600-0838 VL - 30 IS - 2 SP - 272 EP - 280 PB - Wiley CY - Oxford ER - TY - JOUR A1 - Stäudle, Benjamin A1 - Seynnes, Olivier A1 - Laps, Guido A1 - Brüggemann, Gert-Peter A1 - Albracht, Kirsten T1 - Altered gastrocnemius contractile behavior in former achilles tendon rupture patients during walking JF - Frontiers in Physiology N2 - Achilles tendon rupture (ATR) remains associated with functional limitations years after injury. Architectural remodeling of the gastrocnemius medialis (GM) muscle is typically observed in the affected leg and may compensate force deficits caused by a longer tendon. Yet patients seem to retain functional limitations during—low-force—walking gait. To explore the potential limits imposed by the remodeled GM muscle-tendon unit (MTU) on walking gait, we examined the contractile behavior of muscle fascicles during the stance phase. In a cross-sectional design, we studied nine former patients (males; age: 45 ± 9 years; height: 180 ± 7 cm; weight: 83 ± 6 kg) with a history of complete unilateral ATR, approximately 4 years post-surgery. Using ultrasonography, GM tendon morphology, muscle architecture at rest, and fascicular behavior were assessed during walking at 1.5 m⋅s–1 on a treadmill. Walking patterns were recorded with a motion capture system. The unaffected leg served as control. Lower limbs kinematics were largely similar between legs during walking. Typical features of ATR-related MTU remodeling were observed during the stance sub-phases corresponding to series elastic element (SEE) lengthening (energy storage) and SEE shortening (energy release), with shorter GM fascicles (36 and 36%, respectively) and greater pennation angles (8° and 12°, respectively). However, relative to the optimal fascicle length for force production, fascicles operated at comparable length in both legs. Similarly, when expressed relative to optimal fascicle length, fascicle contraction velocity was not different between sides, except at the time-point of peak series elastic element (SEE) length, where it was 39 ± 49% lower in the affected leg. Concomitantly, fascicles rotation during contraction was greater in the affected leg during the whole stance-phase, and architectural gear ratios (AGR) was larger during SEE lengthening. Under the present testing conditions, former ATR patients had recovered a relatively symmetrical walking gait pattern. Differences in seen AGR seem to accommodate the profound changes in MTU architecture, limiting the required fascicle shortening velocity. Overall, the contractile behavior of the GM fascicles does not restrict length- or velocity-dependent force potentials during this locomotor task. KW - tendon rupture KW - muscle fascicle behavior KW - walking gait KW - force generation KW - ultrasound imaging Y1 - 2022 U6 - http://dx.doi.org/10.3389/fphys.2022.792576 SN - 1664-042X VL - 13 PB - Frontiers Research Foundation CY - Lausanne ER - TY - JOUR A1 - Stäudle, Benjamin A1 - Seynnes, Olivier A1 - Laps, Guido A1 - Göll, Fabian A1 - Brüggemann, Gert-Peter A1 - Albracht, Kirsten T1 - Recovery from achilles tendon repair: a combination of Postsurgery Outcomes and Insufficient remodeling of muscle and tendon JF - Medicine & Science in Sports & Exercise N2 - Achilles tendon rupture (ATR) patients have persistent functional deficits in the triceps surae muscle–tendon unit (MTU). The complex remodeling of the MTU accompanying these deficits remains poorly understood. The purpose of the present study was to associate in vivo and in silico data to investigate the relations between changes inMTU properties and strength deficits inATR patients. Methods: Elevenmale subjects who had undergone surgical repair of complete unilateral ATR were examined 4.6 ± 2.0 (mean ± SD) yr after rupture. Gastrocnemius medialis (GM) tendon stiffness, morphology, and muscle architecture were determined using ultrasonography. The force–length relation of the plantar flexor muscles was assessed at five ankle joint angles. In addition, simulations (OpenSim) of the GM MTU force–length properties were performed with various iterations of MTU properties found between the unaffected and the affected side. Results: The affected side of the patients displayed a longer, larger, and stiffer GM tendon (13% ± 10%, 105% ± 28%, and 54% ± 24%, respectively) compared with the unaffected side. The GM muscle fascicles of the affected side were shorter (32% ± 12%) and with greater pennation angles (31% ± 26%). A mean deficit in plantarflexion moment of 31% ± 10% was measured. Simulations indicate that pairing an intact muscle with a longer tendon shifts the optimal angular range of peak force outside physiological angular ranges, whereas the shorter muscle fascicles and tendon stiffening seen in the affected side decrease this shift, albeit incompletely. Conclusions: These results suggest that the substantial changes in MTU properties found in ATR patients may partly result from compensatory remodeling, although this process appears insufficient to fully restore muscle function. KW - Tendon Rupture KW - Stiffness KW - Simulation KW - Muscle Force KW - Muscle Fascicle Y1 - 2021 U6 - http://dx.doi.org/10.1249/MSS.0000000000002592 SN - 1530-0315 VL - 53 IS - 7 SP - 1356 EP - 1366 PB - American College of Sports Medicine CY - Philadelphia, Pa. ER - TY - CHAP A1 - Suryoputri, Nathania A1 - Ghaderi, Aydin A1 - Linder, Peter A1 - Kotliar, Konstantin A1 - Göttler, Jens A1 - Sorg, Christian A1 - Grimmer, Timo ED - Erni, Daniel ED - Fischerauer, Alice ED - Himmel, Jörg ED - Seeger, Thomas ED - Thelen, Klaus T1 - Does hemodynamic response function change in Alzheimer disease? T2 - 2nd YRA MedTech Symposium 2017 : June 8th - 9th / 2017 / Hochschule Ruhr-West Y1 - 2017 SN - 978-3-9814801-9-1 U6 - http://dx.doi.org/10.17185/duepublico/43984 N1 - A young researchers track of the 7th IEEE Workshop & SENSORICA 2017 SP - 92 PB - Universität Duisburg-Essen CY - Duisburg ER - TY - JOUR A1 - Temiz Artmann, Aysegül A1 - Akhisaroglu, M. A1 - Sercan, Z. A1 - Kayatekin, B. M. T1 - Adhesion of Erythrocytes to Endothelial Cells After Acute Exercise: Differences in Red Blood Cells from Juvenile and Adult Rats. Temiz Artmann, A.; Akhisaroglu, M.; Sercan, Z.; Kayatekin, BM.; Yorukoglu, K.; Kirkali, G. JF - Physiological Research (2005) Y1 - 2005 SN - 0862-8408 N1 - pre-press article ER - TY - JOUR A1 - Temiz Artmann, Aysegül A1 - Cavdar, C. A1 - Yenicerioglu, Y. A1 - Caliskan, S. T1 - The effects of intravenous iron treatment on oxidant stress and erythrocyte deformability in haemodialysis patients. Cavdar, C.; Temiz, A.; Yenicerioglu, Y.; Caliskan, S.; Celik, A.; Sifil, A.; Onvural, B.; Camsari, T. JF - Scandinavian Journal of Urology and Nephrology. 37 (2003), H. 1 Y1 - 2003 SN - 0036-5599 SP - 77 EP - 82 ER - TY - JOUR A1 - Temiz Artmann, Aysegül A1 - Kayatekin, Muammer B. A1 - Uysal, N. A1 - Resmi, H. T1 - Does antioxidant supplementation alter the effects of acute exercise on erythrocyte aggregation, deformability and endothelium adhesion in untrained rats? Kayatekin, Muammer B.; Uysal N.; Resmi, H.; Bediz, Seref C.; Temiz Artmann, A.; Genç, S.; Tugyan, K. JF - International Journal for Vitamin and Nutrition Research. 75 (2005), H. 4 Y1 - 2005 SN - 0300-9831 SP - 243 EP - 250 ER - TY - JOUR A1 - Temiz Artmann, Aysegül A1 - Kayser, Peter T1 - Why is Sepsis an Ongoing Clinical Challenge? Lipopolysaccharide Effects on Red Blood Cell Volume / Temiz, Aysegül ; Kayser, Peter JF - Bioengineering in Cell and Tissue Research / Artmann, Gerhard M. ; Chien, Shu (Eds.) Y1 - 2008 SN - 978-3-540-75408-4 SP - 497 EP - 508 PB - Springer CY - Berlin ER - TY - JOUR A1 - Temiz Artmann, Aysegül A1 - Kurulgan demirci, Eylem A1 - Fırat, Ipek Seda A1 - Oflaz, Hakan A1 - Artmann, Gerhard T1 - Recombinant activated protein C (rhAPC) affects lipopolysaccharide-induced mechanical compliance changes and beat frequency of mESC-derived cardiomyocyte monolayers JF - SHOCK KW - Septic cardiomyopathy KW - LPS KW - cardiomyocyte biomechanics KW - CellDrum KW - actin cytoskeleton Y1 - 2021 U6 - http://dx.doi.org/10.1097/SHK.0000000000001845 SN - 1540-0514 PB - Wolters Kluwer CY - Köln ER - TY - JOUR A1 - Temiz Artmann, Aysegül A1 - Linder, Peter A1 - Kayser, Peter A1 - Digel, Ilya T1 - NMR in vitro effects on proliferation, apoptosis, and viability of human chondrocytes and osteoblasts JF - Methods and findings in Experimental and Clinical Pharmacology. 27 (2005), H. 6 Y1 - 2005 SN - 0379-0355 SP - 391 EP - 394 ER - TY - JOUR A1 - Temiz Artmann, Aysegül A1 - Resmi, Halil A1 - Akhunlar, Hülya A1 - Güner, Gül T1 - In vitro effects of high glucose concentrations on membrane protein sulfhydryl oxidation, G-actin and deformability of human erythrocytes. Resmi, Halil ; Akhunlar, Hülya ; Temiz Artmann, Aysegül ; Güner, Gül JF - Cell biochemistry and function. 23 (2005), H. 3 Y1 - 2005 SN - 0263-6484 SP - 163 EP - 168 ER - TY - JOUR A1 - Temiz Artmann, Aysegül A1 - Saklamaz, Ali A1 - Comlekci, Abdurrahman A1 - Caliskan, Sezer T1 - The beneficial effects of lipid-lowering drugs beyond lipid-lowering effects: A comparative study with pravastatin, atorvastatin, and fenofibrate in patients with type IIa and type IIb hyperlipidemia / Saklamaz, Ali ; Comlekci, Abdurrahman ; Temiz, Aysegu JF - Metabolism. 54 (2005), H. 5 Y1 - 2005 SN - 0026-0495 SP - 677 EP - 681 ER - TY - JOUR A1 - Temiz Artmann, Aysegül A1 - Yalcin, Ozlem A1 - Resmi, Halil A1 - Baskurt, Oguz K. T1 - Can white blood cell activation be one of the major factors that affect hemorheological parameters during and after exercise? JF - Clinical Hemorheology and Microcirculation. 26 (2002), H. 3 Y1 - 2002 SN - 1386-0291 N1 - = The 11th European Symposium on Clinical Hemorheology, Rouen, France, 19-22 September 2000 SP - 189 EP - 193 ER - TY - CHAP A1 - Tepecik, Atakan ED - Digel, Ilya ED - Staat, Manfred ED - Trzewik, Jürgen ED - Sielemann, Stefanie ED - Erni, Daniel ED - Zylka, Waldemar T1 - AstroBioLab: Review of technical and bioanalytical approaches T2 - 4th YRA MedTech Symposium 2024 : February 1 / 2024 / FH Aachen N2 - This study presents the concept of AstroBioLab, an autonomous astrobiological field laboratory tailored for the exploration of (sub)glacial habitats. AstroBioLab is an integral component of the TRIPLE (Technologies for Rapid Ice Penetration and subglacial Lake Exploration) DLR-funded project, aimed at advancing astrobiology research through the development and deployment of innovative technologies. AstroBioLab integrates diverse measurement techniques such as fluorescence microscopy, DNA sequencing and fluorescence spectrometry, while leveraging microfluidics for efficient sample delivery and preparation. Y1 - 2024 SN - 978-3-940402-65-3 U6 - http://dx.doi.org/10.17185/duepublico/81475 SP - 33 EP - 34 PB - Universität Duisburg-Essen CY - Duisburg ER - TY - JOUR A1 - Thiebes, Anja Lena A1 - Klein, Sarah A1 - Zingsheim, Jonas A1 - Möller, Georg H. A1 - Gürzing, Stefanie A1 - Reddemann, Manuel A. A1 - Behbahani, Mehdi A1 - Cornelissen, Christian G. T1 - Effervescent atomizer as novel cell spray technology to decrease the gas-to-liquid ratio JF - pharmaceutics N2 - Cell spraying has become a feasible application method for cell therapy and tissue engineering approaches. Different devices have been used with varying success. Often, twin-fluid atomizers are used, which require a high gas velocity for optimal aerosolization characteristics. To decrease the amount and velocity of required air, a custom-made atomizer was designed based on the effervescent principle. Different designs were evaluated regarding spray characteristics and their influence on human adipose-derived mesenchymal stromal cells. The arithmetic mean diameters of the droplets were 15.4–33.5 µm with decreasing diameters for increasing gas-to-liquid ratios. The survival rate was >90% of the control for the lowest gas-to-liquid ratio. For higher ratios, cell survival decreased to approximately 50%. Further experiments were performed with the design, which had shown the highest survival rates. After seven days, no significant differences in metabolic activity were observed. The apoptosis rates were not influenced by aerosolization, while high gas-to-liquid ratios caused increased necrosis levels. Tri-lineage differentiation potential into adipocytes, chondrocytes, and osteoblasts was not negatively influenced by aerosolization. Thus, the effervescent aerosolization principle was proven suitable for cell applications requiring reduced amounts of supplied air. This is the first time an effervescent atomizer was used for cell processing. KW - tri-lineage differentiation KW - survival KW - twin-fluid atomizer KW - adipose-derived stromal cells (ASCs) KW - cell atomization KW - cell aerosolization Y1 - 2022 U6 - http://dx.doi.org/10.3390/pharmaceutics14112421 N1 - This article belongs to the Special Issue "Stromal, Stem, Signaling Cells: The Multiple Roles and Applications of Mesenchymal Cells" VL - 14 IS - 11 PB - MDPI CY - Basel ER - TY - GEN A1 - Topcu, Murat A1 - Madabhushi, Gopal Santana Phani A1 - Staat, Manfred T1 - Datasets from FEM Simulations done with COMSOL Multiphysics and Code_Aster N2 - Datasets from FEM Simulations done with COMSOL Multiphysics and Code_Aster for an elastic stress transfer between matrix and fibres having a variable radius. KW - Natural fibres KW - Polymer-matrix composites KW - Biocomposites KW - Stress concentrations KW - Finite element analysis (FEA) Y1 - 2022 U6 - http://dx.doi.org/10.6084/m9.figshare.19333295.v2 ER - TY - JOUR A1 - Topçu, Murat A1 - Madabhushi, Gopal S.P. A1 - Staat, Manfred T1 - A generalized shear-lag theory for elastic stress transfer between matrix and fibres having a variable radius JF - International Journal of Solids and Structures N2 - A generalized shear-lag theory for fibres with variable radius is developed to analyse elastic fibre/matrix stress transfer. The theory accounts for the reinforcement of biological composites, such as soft tissue and bone tissue, as well as for the reinforcement of technical composite materials, such as fibre-reinforced polymers (FRP). The original shear-lag theory proposed by Cox in 1952 is generalized for fibres with variable radius and with symmetric and asymmetric ends. Analytical solutions are derived for the distribution of axial and interfacial shear stress in cylindrical and elliptical fibres, as well as conical and paraboloidal fibres with asymmetric ends. Additionally, the distribution of axial and interfacial shear stress for conical and paraboloidal fibres with symmetric ends are numerically predicted. The results are compared with solutions from axisymmetric finite element models. A parameter study is performed, to investigate the suitability of alternative fibre geometries for use in FRP. KW - Natural fibres KW - Polymer-matrix composites KW - Biocomposites KW - Stress concentrations KW - Finite element analysis Y1 - 2022 U6 - http://dx.doi.org/10.1016/j.ijsolstr.2022.111464 SN - 0020-7683 VL - 239–240 IS - Art. No. 111464 PB - Elsevier CY - New York, NY ER - TY - JOUR A1 - Tran, Linda A1 - Mottaghy, K. A1 - Arlt-Körfer, Sabine A1 - Waluga, Christian A1 - Behbahani, Mehdi T1 - An experimental study of shear-dependent human platelet adhesion and underlying protein-binding mechanisms in a cylindrical Couette system JF - Biomedizinische Technik Y1 - 2017 U6 - http://dx.doi.org/10.1515/bmt-2015-0034 SN - 0013-5585 VL - 62 IS - 4 SP - 383 EP - 392 PB - De Gruyter CY - Berlin ER - TY - CHAP A1 - Tran, N. T. A1 - Tran, Thanh Ngoc A1 - Matthies, M. G. A1 - Stavroulakis, G. E. A1 - Staat, Manfred T1 - Shakedown Analysis Under Stochastic Uncertainty by Chance Constrained Programming T2 - Advances in Direct Methods for Materials and Structures N2 - In this paper we propose a stochastic programming method to analyse limit and shakedown of structures under uncertainty condition of strength. Based on the duality theory, the shakedown load multiplier formulated by the kinematic theorem is proved actually to be the dual form of the shakedown load multiplier formulated by static theorem. In this investigation a dual chance constrained programming algorithm is developed to calculate simultaneously both the upper and lower bounds of the plastic collapse limit and the shakedown limit. The edge-based smoothed finite element method (ES-FEM) with three-node linear triangular elements is used for structural analysis. Y1 - 2017 SN - 978-3-319-59810-9 U6 - http://dx.doi.org/10.1007/978-3-319-59810-9_6 SP - 85 EP - 103 PB - Springer CY - Cham ER - TY - THES A1 - Tran, Ngoc Trinh T1 - Limit and Shakedown analysis of structures under stochastic conditions Y1 - 2019 U6 - http://dx.doi.org/10.24355/dbbs.084-201902121135-0 PB - Technische Universität Braunschweig CY - Braunschweig ER - TY - CHAP A1 - Tran, Ngoc Trinh A1 - Matthies, Hermann G. A1 - Stavroulakis, Georgios Eleftherios A1 - Staat, Manfred T1 - Direct plastic structural design by chance constrained programming T2 - 6th European Conference on Computational Mechanics (ECCM 6), 7th European Conference on Computational Fluid Dynamics (ECFD 7), 11-15 June 2018, Glasgow, UK N2 - We propose a stochastic programming method to analyse limit and shakedown of structures under random strength with lognormal distribution. In this investigation a dual chance constrained programming algorithm is developed to calculate simultaneously both the upper and lower bounds of the plastic collapse limit or the shakedown limit. The edge-based smoothed finite element method (ES-FEM) using three-node linear triangular elements is used. Y1 - 2018 ER - TY - JOUR A1 - Tran, Ngoc Trinh A1 - Staat, Manfred T1 - Direct plastic structural design under lognormally distributed strength by chance constrained programming JF - Optimization and Engineering N2 - We propose the so-called chance constrained programming model of stochastic programming theory to analyze limit and shakedown loads of structures under random strength with a lognormal distribution. A dual chance constrained programming algorithm is developed to calculate simultaneously both the upper and lower bounds of the plastic collapse limit and the shakedown limit. The edge-based smoothed finite element method (ES-FEM) is used with three-node linear triangular elements. Y1 - 2020 U6 - http://dx.doi.org/10.1007/s11081-019-09437-2 SN - 1573-2924 VL - 21 IS - 1 SP - 131 EP - 157 PB - Springer Nature CY - Cham ER - TY - JOUR A1 - Tran, Ngoc Trinh A1 - Staat, Manfred T1 - Direct plastic structural design under random strength and random load by chance constrained programming JF - European Journal of Mechanics - A/Solids Y1 - 2021 U6 - http://dx.doi.org/10.1016/j.euromechsol.2020.104106 SN - 0997-7538 VL - 85 IS - Article 104106 PB - Elsevier CY - Amsterdam ER - TY - CHAP A1 - Tran, Ngoc Trinh A1 - Staat, Manfred T1 - FEM shakedown analysis of Kirchhoff-Love plates under uncertainty of strength T2 - Proceedings of UNCECOMP 2021 N2 - A new formulation to calculate the shakedown limit load of Kirchhoff plates under stochastic conditions of strength is developed. Direct structural reliability design by chance con-strained programming is based on the prescribed failure probabilities, which is an effective approach of stochastic programming if it can be formulated as an equivalent deterministic optimization problem. We restrict uncertainty to strength, the loading is still deterministic. A new formulation is derived in case of random strength with lognormal distribution. Upper bound and lower bound shakedown load factors are calculated simultaneously by a dual algorithm. Y1 - 2021 SN - 978-618-85072-6-5 U6 - http://dx.doi.org/10.7712/120221.8041.19047 N1 - Proceedings of UNCECOMP 2021, 4th International Conference on Uncertainty Quantification in Computational Sciences and Engineering, streamed from Athens, Greece, 28–30 June 2021. SP - 323 EP - 338 ER - TY - CHAP A1 - Tran, Ngoc Trinh A1 - Staat, Manfred A1 - Stavroulakis, G. E. ED - Onate, E. T1 - A multicriteria method for truss optimization T2 - 11th World Congress on Computational Mechanics (WCCM XI) ; 5th European Conference on Computational Mechanics (ECCM V) ; 6th European Conference on Computational Fluid Dynamics (ECFD VI) ; July 20-25, 2014, Barcelona Y1 - 2014 SP - 1 EP - 12 ER - TY - CHAP A1 - Tran, Ngoc Trinh A1 - Tran, Thanh Ngoc A1 - Matthies, H. G. A1 - Stavroulakis, G. E. A1 - Staat, Manfred ED - Papadrakakis, M. T1 - Shakedown analysis of plate bending analysis under stochastic uncertainty by chance constrained programming T2 - ECCOMAS Congress 2016, VII European Congress on Computational Methods in Applied Sciences and Engineering. Crete Island, Greece, 5–10 June 2016 Y1 - 2016 ER - TY - CHAP A1 - Tran, Ngoc Trinh A1 - Tran, Thanh Ngoc A1 - Matthies, Hermann G. A1 - Stavroulakis, Georgios Eleftherios A1 - Staat, Manfred T1 - FEM Shakedown of uncertain structures by chance constrained programming T2 - PAMM Proceedings in Applied Mathematics and Mechanics Y1 - 2016 U6 - http://dx.doi.org/10.1002/pamm.201610346 SN - 1617-7061 N1 - Special Issue: Joint 87th Annual Meeting of the International Association of Applied Mathematics and Mechanics (GAMM) and Deutsche Mathematiker-Vereinigung VL - 16 IS - 1 SP - 715 EP - 716 ER - TY - CHAP A1 - Tran, Ngoc Trinh A1 - Trinh, Tu Luc A1 - Dao, Ngoc Tien A1 - Giap, Van Tan A1 - Truong, Manh Khuyen A1 - Dinh, Thuy Ha A1 - Staat, Manfred T1 - Limit and shakedown analysis of structures under random strength T2 - Proceedings of (NACOME2022) The 11th National Conference on Mechanics, Vol. 1. Solid Mechanics, Rock Mechanics, Artificial Intelligence, Teaching and Training, Hanoi, December 2-3, 2022 N2 - Direct methods comprising limit and shakedown analysis is a branch of computational mechanics. It plays a significant role in mechanical and civil engineering design. The concept of direct method aims to determinate the ultimate load bearing capacity of structures beyond the elastic range. For practical problems, the direct methods lead to nonlinear convex optimization problems with a large number of variables and onstraints. If strength and loading are random quantities, the problem of shakedown analysis is considered as stochastic programming. This paper presents a method so called chance constrained programming, an effective method of stochastic programming, to solve shakedown analysis problem under random condition of strength. In this our investigation, the loading is deterministic, the strength is distributed as normal or lognormal variables. KW - Reliability of structures KW - Stochastic programming KW - Chance constrained programming KW - Shakedown analysis KW - Limit analysis Y1 - 2022 SN - 978-604-357-084-7 SP - 510 EP - 518 PB - Nha xuat ban Khoa hoc tu nhien va Cong nghe (Verlag Naturwissenschaft und Technik) CY - Hanoi ER - TY - JOUR A1 - Tran, Ngoc Trinh A1 - Trinh, Tu Luc A1 - Dao, Ngoc Tien A1 - Giap, Van Tan A1 - Truong, Manh Khuyen A1 - Dinh, Thuy Ha A1 - Staat, Manfred T1 - FEM shakedown analysis of structures under random strength with chance constrained programming JF - Vietnam Journal of Mechanics N2 - Direct methods, comprising limit and shakedown analysis, are a branch of computational mechanics. They play a significant role in mechanical and civil engineering design. The concept of direct methods aims to determine the ultimate load carrying capacity of structures beyond the elastic range. In practical problems, the direct methods lead to nonlinear convex optimization problems with a large number of variables and constraints. If strength and loading are random quantities, the shakedown analysis can be formulated as stochastic programming problem. In this paper, a method called chance constrained programming is presented, which is an effective method of stochastic programming to solve shakedown analysis problems under random conditions of strength. In this study, the loading is deterministic, and the strength is a normally or lognormally distributed variable. KW - limit analysis KW - shakedown analysis KW - chance constrained programming KW - stochastic programming KW - reliability of structures Y1 - 2022 U6 - http://dx.doi.org/10.15625/0866-7136/17943 SN - 0866-7136 SN - 2815-5882 VL - 44 IS - 4 SP - 459 EP - 473 PB - Vietnam Academy of Science and Technology (VAST) ER - TY - THES A1 - Tran, Thanh Ngoc T1 - Limit and shakedown analysis of plates and shells including uncertainties Y1 - 2008 N1 - Chemnitz, Techn. Univ., Diss., 2008 ER - TY - JOUR A1 - Tran, Thanh Ngoc A1 - Kreißig, R. A1 - Staat, Manfred T1 - Probabilistic limit and shakedown analysis of thin plates and shells JF - Structural safety. 31 (2009), H. 1 Y1 - 2009 SN - 0167-4730 SP - 1 EP - 18 PB - - ER - TY - JOUR A1 - Tran, Thanh Ngoc A1 - Kreißig, R. A1 - Vu, Duc Khoi A1 - Staat, Manfred T1 - Upper bound limit and shakedown analysis of shells using the exact Ilyushin yield surface JF - Computer & Structures. 86 (2008) Y1 - 2008 SN - 0045-7949 SP - 1683 EP - 1695 ER - TY - CHAP A1 - Tran, Thanh Ngoc A1 - Novacek, V. A1 - Tolba, R. A1 - Klinge, U. A1 - Turquier, F. A1 - Staat, Manfred T1 - Experimental and Computational approach to study colorectal anastomosis. ISB2011, Proceedings of the XXIII Congress of the International Society of Biomechanics, Brussels, Belgium, July 3-7, 2011 N2 - Summary: This paper presents a methodology to study and understand the mechanics of stapled anastomotic behaviors by combining empirical experimentation and finite element analysis. Performance of stapled anastomosis is studied in terms of leakage and numerical results which are compared to in vitro experiments performed on fresh porcine tissue. Results suggest that leaks occur between the tissue and staple legs penetrating through the tissue. KW - Anastomose KW - Finite-Elemente-Methode KW - Biomechanik KW - Anastomosis KW - Finite element method KW - Biomechanics Y1 - 2011 ER - TY - CHAP A1 - Tran, Thanh Ngoc A1 - Pham, Phu Tinh A1 - Staat, Manfred T1 - Reliability analysis of shells based on direct plasticity methods N2 - Abstracts der CD-Rom Proceedings of the 8th World Congress on Computational Mechanics (WCCM8) and 5th Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS 2008) 30.06. - 04.07.2008 Venedig, Italien. 2 Seiten Zusammenfassung der Autoren mit graph. Darst. und Literaturverzeichnis N2 - Abstracts of the Proceedings of the 8th World Congress on Computational Mechanics (WCCM8) and 5th Congress on Computational Methods in Applied Sciences and Engineering (ECCOMAS 2008) June 30th - July, 4th 2008, Venice, Italy. 2 pages with abstracts of the authors, Ill. and references. KW - Finite-Elemente-Methode KW - Limit analysis KW - Shakedown analysis KW - First-order reliability method KW - second-order reliability method KW - Sensitivity Y1 - 2008 ER - TY - JOUR A1 - Tran, Thanh Ngoc A1 - Pham, Phu Tinh A1 - Vu, D. K. A1 - Staat, Manfred T1 - Reliability Analysis of Inelastic Shell Structures Under Variable Loads JF - Limit States of Materials and Structures : Direct Methods / Hrsg. Dieter Weichert; Hrsg. Alan Ponter Y1 - 2009 SN - 978-1-4020-9633-4 SP - 135 EP - 156 PB - Springer Netherland CY - Berlin ER - TY - JOUR A1 - Tran, Thanh Ngoc A1 - Staat, Manfred T1 - Shakedown analysis of two dimensional structures by an edge-based smoothed finite element method Y1 - 2010 N1 - ECCM 2010, IV European Conference on Computational Mechanics, Paris, France, May 16-21, 2010. SP - 1 EP - 7 ER - TY - JOUR A1 - Tran, Thanh Ngoc A1 - Staat, Manfred T1 - An Edge-Based Smoothed Finite Element Method for Primal-Dual Shakedown Analysis of Structures Under Uncertainties JF - Limit State of Materials and Structures : Direct Methods 2. Saxcé, Géry de (Hrsg.) Y1 - 2013 SN - 978-94-007-5424-9 SP - 89 EP - 102 PB - Springer CY - Dordrecht ER -