Refine
Year of publication
Document Type
- Conference Proceeding (161) (remove)
Keywords
- Finite-Elemente-Methode (11)
- Einspielen <Werkstoff> (6)
- shakedown analysis (6)
- Clusterion (4)
- Limit analysis (4)
- Sonde (4)
- limit analysis (4)
- solar sail (4)
- Air purification (3)
- Eisschicht (3)
- Hämoglobin (3)
- Luftreiniger (3)
- MASCOT (3)
- Plasmacluster ion technology (3)
- Raumluft (3)
- Shakedown (3)
- Shakedown analysis (3)
- Traglast (3)
- Bruchmechanik (2)
- Einspielanalyse (2)
- Erythrozyt (2)
- FEM (2)
- GOSSAMER-1 (2)
- Kohlenstofffaser (2)
- Lipopolysaccharide (2)
- Ratcheting (2)
- Spacecraft (2)
- Stickstoffmonoxid (2)
- Traglastanalyse (2)
- Trajectory Optimization (2)
- celldrum technology (2)
- lipopolysaccharides (2)
- multiple NEA rendezvous (2)
- nitric oxide gas (2)
- ratchetting (2)
- shakedown (2)
- small spacecraft (2)
- Adsorption (1)
- Analytischer Zulaessigkeitsnachweis (1)
- Anastomose (1)
- Anastomosis (1)
- Antarctica (1)
- Asteroid Deflection (1)
- Attitude dynamics (1)
- Autofluoreszenzverfahren (1)
- Automated Optimization (1)
- Bakterien (1)
- Biomechanics (1)
- Biomechanik (1)
- Biomedizinische Technik (1)
- Chance constrained programming (1)
- Dattel (1)
- Dekontamination (1)
- Druckbeanspruchung (1)
- Druckbehälter (1)
- Druckbelastung (1)
- EEG (1)
- Einspiel-Analyse (1)
- Elastodynamik (1)
- Elektrodynamik (1)
- Endothelzelle (1)
- Evolution of damage (1)
- Evolutionary Neurocontrol (1)
- Exact Ilyushin yield surface (1)
- Extension fracture (1)
- Extension strain criterion (1)
- FEM-Programm (1)
- FEM-computation (1)
- Fehlerstellen (1)
- Festkörper (1)
- Fibroblast (1)
- Finite element method (1)
- First Order Reliabiblity Method (1)
- First-order reliability method (1)
- Force (1)
- Gossamer (1)
- Gossamer structures (1)
- Hybrid Propellants (1)
- Hydrodynamik (1)
- Hydrogel (1)
- Impedance Spectroscopy (1)
- Interplanetary flight (1)
- Iterative learning control (1)
- Jupiter (1)
- Knee (1)
- Körpertemperatur (1)
- LISA (1)
- Lichtstreuungsbasierte Instrumente (1)
- Load modeling (1)
- Low-Thrust Propulsion (1)
- Mars (1)
- Mechanische Beanspruchung (1)
- Mohr–Coulomb criterion (1)
- Multi-dimensional wave propagation (1)
- Multiphase (1)
- Natriumhypochlorit (1)
- Nichtlineare Gleichung (1)
- Nichtlineare Optimierung (1)
- Nichtlineare Welle (1)
- Orbital dynamics (1)
- PFM (1)
- PHILAE (1)
- Pflanzenphysiologie (1)
- Pflanzenscanner (1)
- Planetary Protection (1)
- Planetary exploration (1)
- Proteine (1)
- Random variable (1)
- Reliability of structures (1)
- Reusable Rocket Engines (1)
- Rohr (1)
- Rohrbruch (1)
- Sensitivity (1)
- Sepsis (1)
- Sequence-Search (1)
- Sleep EEG (1)
- Small Solar System Body Lander (1)
- Small Spacecraft (1)
- Solar Power Sail (1)
- Solar Sail (1)
- Solar sail (1)
- Spacecraft Trajectory Optimization (1)
- Stahl (1)
- Stochastic programming (1)
- Technische Mechanik (1)
- Torsion (1)
- Torsionsbelastung (1)
- Tragfähigkeit (1)
- Training (1)
- Wasserbrücke (1)
- Wasserstoffperoxid (1)
- Wellen (1)
- Zug-Druck-Beanspruchung (1)
- Zug-Druck-Belastung (1)
- activated nanostructured carbon (1)
- aktivierte nanostrukturierte Kohlenstofffaser (1)
- asteroid lander (1)
- asteroid sample return (1)
- autofluorescence-based detection system (1)
- biopotential electrodes (1)
- burst pressure (1)
- burst tests (1)
- contractile tension (1)
- cytosolic water diffusion (1)
- date palm tree (1)
- design-by-analysis (1)
- finite element analysis (1)
- flaw (1)
- flotilla missions (1)
- habitability (1)
- heliosphere (1)
- hemoglobin (1)
- hemoglobin dynamics (1)
- hydrogel (1)
- ice moons (1)
- icy moons (1)
- ion propulsion (1)
- kontraktile Spannung (1)
- life detection (1)
- light scattering analysis (1)
- limit and shakedown analysis (1)
- limit load (1)
- linear kinematic hardening (1)
- load carrying capacity (1)
- load limit (1)
- low-thrust (1)
- low-thrust trajectory optimization (1)
- lower bound theorem (1)
- material shakedown (1)
- mechanical waves (1)
- nanostructured carbonized plant parts (1)
- nanostrukturierte carbonisierte Pflanzenteile (1)
- near-Earth asteroid (1)
- nonlinear kinematic hardening (1)
- nonlinear optimization (1)
- nonlinear solids (1)
- nonlinear tensor constitutive equation (1)
- pipes (1)
- planetary defence (1)
- plant scanner (1)
- plasma generated ions (1)
- plastic deformation (1)
- probabilistic fracture mechanics (1)
- protein (1)
- reliability (1)
- responsive space (1)
- rhAPC (1)
- sample return (1)
- second-order reliability method (1)
- sensors (1)
- small solar system body characterisation (1)
- small spacecraft asteroid lander (1)
- small spacecraft solar sail (1)
- solar sails (1)
- solar system (1)
- space missions (1)
- subglacial aquatic ecosystems (1)
- subsurface ice (1)
- subsurface ice research (1)
- subsurface probe (1)
- system engineering (1)
- tension–torsion loading (1)
- underwater vehicle (1)
- vessels (1)
- water bridge phenomenon (1)
Biomechanical simulation of different prosthetic meshes for repairing uterine/vaginal vault prolapse
(2017)
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.
Electromechanical model of hiPSC-derived ventricular cardiomyocytes cocultured with fibroblasts
(2018)
The CellDrum provides an experimental setup to study the mechanical effects of fibroblasts co-cultured with hiPSC-derived ventricular cardiomyocytes. Multi-scale computational models based on the Finite Element Method are developed. Coupled electrical cardiomyocyte-fibroblast models (cell level) are embedded into reaction-diffusion equations (tissue level) which compute the propagation of the action potential in the cardiac tissue. Electromechanical coupling is realised by an excitation-contraction model (cell level) and the active stress arising during contraction is added to the passive stress in the force balance, which determines the tissue displacement (tissue level). Tissue parameters in the model can be identified experimentally to the specific sample.
The overall objective of this study is to develop a new external fixator, which closely maps the native kinematics of the elbow to decrease the joint force resulting in reduced rehabilitation time and pain. An experimental setup was designed to determine the native kinematics of the elbow during flexion of cadaveric arms. As a preliminary study, data from literature was used to modify a published biomechanical model for the calculation of the joint and muscle forces. They were compared to the original model and the effect of the kinematic refinement was evaluated. Furthermore, the obtained muscle forces were determined in order to apply them in the experimental setup. The joint forces in the modified model differed slightly from the forces in the original model. The muscle force curves changed particularly for small flexion angles but their magnitude for larger angles was consistent.
The vaginal prolapse after hysterectomy (removal of the uterus) is often associated with the prolapse of the vaginal vault, rectum, bladder, urethra or small bowel. Minimally
invasive surgery such as laparoscopic sacrocolpopexy and pectopexy are widely performed for the treatment of the vaginal prolapse with weakly supported vaginal vault after hysterectomy using prosthetic mesh implants to support (or strengthen) lax apical ligaments. Implants of different shape, size and polymers are selected depending on the patient’s anatomy and the surgeon’s preference. In this computational study on pectopexy, DynaMesh®-PRP soft, GYNECARE GYNEMESH® PS Nonabsorbable PROLENE® soft and Ultrapro® are tested in a 3D finite element model of the female pelvic floor. The mesh model is implanted into the extraperitoneal space and sutured to the vaginal stump with a bilateral fixation to the iliopectineal ligament at both sides. Numerical simulations are conducted at rest, after surgery and during Valsalva maneuver with weakened tissues modeled by reduced tissue stiffness. Tissues and prosthetic meshes are modeled as incompressible, isotropic hyperelastic materials. The positions of the organs are calculated with respect to the pubococcygeal line (PCL) for female pelvic floor at rest, after repair and during Valsalva maneuver using the three meshes.
The discovery of human induced pluripotent stem cells reprogrammed from somatic cells [1] and their ability to differentiate into cardiomyocytes (hiPSC-CMs) has provided a robust platform for drug screening [2]. Drug screenings are essential in the development of new components, particularly for evaluating the potential of drugs to induce life-threatening pro-arrhythmias. Between 1988 and 2009, 14 drugs have been removed from the market for this reason [3]. The microelectrode array (MEA) technique is a robust tool for drug screening as it detects the field potentials (FPs) for the entire cell culture. Furthermore, the propagation of the field potential can be examined on an electrode basis. To analyze MEA measurements in detail, we have developed an open-source tool.
Human induced pluripotent stem cells (hiPSCs) have shown to be promising in disease studies and drug screenings [1]. Cardiomyocytes derived from hiPSCs have been extensively investigated using patch-clamping and optical methods to compare their electromechanical behaviour relative to fully matured adult cells. Mathematical models can be used for translating findings on hiPSCCMs to adult cells [2] or to better understand the mechanisms of various ion channels when a drug is applied [3,4]. Paci et al. (2013) [3] developed the first model of hiPSC-CMs, which they later refined based on new data [3]. The model is based on iCells® (Fujifilm Cellular Dynamics, Inc. (FCDI), Madison WI, USA) but major differences among several cell lines and even within a single cell line have been found and motivate an approach for creating sample-specific models. We have developed an optimisation algorithm that parameterises the conductances (in S/F=Siemens/Farad) of the latest Paci et al. model (2018) [5] using current-voltage data obtained in individual patch-clamp experiments derived from an automated patch clamp system (Patchliner, Nanion Technologies GmbH, Munich).
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.
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.
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.