Article
Refine
Year of publication
Institute
- Fachbereich Luft- und Raumfahrttechnik (380) (remove)
Document Type
- Article (380) (remove)
Keywords
- avalanche (5)
- snow (3)
- Aeroelasticity (2)
- CFD (2)
- Drinfeld modules (2)
- Karosseriebau (2)
- Kraftfahrzeugbau (2)
- Obstacle avoidance (2)
- Path planning (2)
- Sportwagen (2)
- Studentenprojekt (2)
- Transcendence (2)
- UAV (2)
- Virtuelle Fahrzeugentwicklung (2)
- car body construction (2)
- t-modules (2)
- 1P hub loads (1)
- Active humidity control (1)
- Actuator disk modelling (1)
- Aircraft sizing (1)
- Antarctic Glaciology (1)
- Automotive safety approach (1)
- Autonomy (1)
- Avalanche (1)
- BET (1)
- Bio-inspired systems (1)
- Blade element method (1)
- CFD propeller simulation (1)
- CO2 emission reduction targets (1)
- Centrifugal twisting moment (1)
- Commercial Vehicle (1)
- Common Rail Injection System (1)
- Cost function (1)
- Crashworthiness (1)
- DLR-ESTEC GOSSAMER roadmap for solar sailing (1)
- Diesel Engine (1)
- Drag estimation (1)
- Driving cycle recognition (1)
- Dry-low-NOx (DLN) combustion (1)
- ECMS (1)
- Electrochemical impedance spectroscopy (1)
- Energy management strategies (1)
- European Transient Cycle (1)
- Extension–twist coupling (1)
- Extraterrestrial Glaciology (1)
- Fault detection (1)
- Finite element method (1)
- Flutter (1)
- Fuel cell (1)
- Full-vehicle crash test (1)
- GOSSAMER-1 (1)
- Glaciological instruments and methods (1)
- Health management system (1)
- High hydrogen combustion (1)
- Higher derivations (1)
- Human factors (1)
- Hydrogen combustion (1)
- Hydrogen gas turbine (1)
- Hyperdifferentials (1)
- Impedance analysis (1)
- Interstellar objects (1)
- Lifting propeller (1)
- Local path planning (1)
- Low-field NMR (1)
- Micromix combustion (1)
- Missions (1)
- Multi-objective optimization (1)
- Multirotor UAS (1)
- NMR exchange relaxometry (1)
- Non-model-based Evaluation (1)
- Online diagnostic (1)
- PEM fuel cell (1)
- Parasitic drag (1)
- Periods (1)
- Predictive battery discharge (1)
- Propeller (1)
- Propeller aerodynamics (1)
- Propeller elasticity (1)
- Propeller performance (1)
- Propeller whirl flutter (1)
- RAMMS (1)
- Relative air humidity (1)
- Selective Catalytic Reduction (1)
- Small spacecraft (1)
- Snow (1)
- Solar sail (1)
- Subclacial exploration (1)
- Subglacial lakes (1)
- Trajectories (1)
- Trapeze effect (1)
- Unmanned aerial vehicles (1)
- Unsteady aerodynamics (1)
- Wind milling (1)
- Wind tunnel experiments (1)
- adaptive systems (1)
- artificial intelligence (1)
- assistance system (1)
- debris flow (1)
- eVTOL development (1)
- eVTOL safety (1)
- fuel cell vehicle (1)
- gamification (1)
- intelligent control (1)
- intelligent energy management (1)
- machine learning (1)
- manufacturing (1)
- optimization system (1)
Digital elevation models (DEMs), represent the three-dimensional terrain and are the basic input for numerical snow avalanche dynamics simulations. DEMs can be acquired using topographic maps or remote-sensing technologies, such as photogrammetry or lidar. Depending on the acquisition technique, different spatial resolutions and qualities are achieved. However, there is a lack of studies that investigate the sensitivity of snow avalanche simulation algorithms to the quality and resolution of DEMs. Here, we perform calculations using the numerical avalance dynamics model RAMMS, varying the quality and spatial resolution of the underlying DEMs, while holding the simulation parameters constant. We study both channelized and open-terrain avalanche tracks with variable roughness. To quantify the variance of these simulations, we use well-documented large-scale avalanche events from Davos, Switzerland (winter 2007/08), and from our large-scale avalanche test site, Valĺee de la Sionne (winter 2005/06). We find that the DEM resolution and quality is critical for modeled flow paths, run-out distances, deposits, velocities and impact pressures. Although a spatial resolution of ~25 m is sufficient for large-scale avalanche modeling, the DEM datasets must be checked carefully for anomalies and artifacts before using them for dynamics calculations.
Digital Image Correlation (DIC) is a powerful tool used to evaluate displacements and deformations in a non-intrusive manner. By comparing two images, one of the undeformed reference state of a specimen and another of the deformed target state, the relative displacement between those two states is determined. DIC is well known and often used for post-processing analysis of in-plane displacements and deformation of specimen. Increasing the analysis speed to enable real-time DIC analysis will be beneficial and extend the field of use of this technique.
Here we tested several combinations of the most common DIC methods in combination with different parallelization approaches in MATLAB and evaluated their performance to determine whether real-time analysis is possible with these methods. To reflect improvements in computing technology different hardware settings were also analysed. We found that implementation problems can reduce the efficiency of a theoretically superior algorithm such that it becomes practically slower than a suboptimal algorithm. The Newton-Raphson algorithm in combination with a modified Particle Swarm algorithm in parallel image computation was found to be most effective. This is contrary to theory, suggesting that the inverse-compositional Gauss-Newton algorithm is superior. As expected, the Brute Force Search algorithm is the least effective method. We also found that the correct choice of parallelization tasks is crucial to achieve improvements in computing speed. A poorly chosen parallelisation approach with high parallel overhead leads to inferior performance. Finally, irrespective of the computing mode the correct choice of combinations of integerpixel and sub-pixel search algorithms is decisive for an efficient analysis. Using currently available hardware realtime analysis at high framerates remains an aspiration.
Solar Sail Kinetic Energy Impactor Trajectory Optimization for an Asteroid-Deflection Mission
(2007)
Solar Sail Trajectory Optimization for Intercepting, Impacting, and Deflecting Near-Earth Asteroids
(2005)
Solar sailcraft of the first generation technology development / Seboldt, Wolfgang ; Dachwald, Bernd
(2003)
Solar Sails for Near- and Medium-Term Scientific Deep Space Missions / W. Sebolt ; B. Dachwald
(2005)
The scientific interest for near-Earth asteroids as well as the interest in potentially hazardous asteroids from the perspective of planetary defense led the space community to focus on near-Earth asteroid mission studies. A multiple near-Earth asteroid rendezvous mission with close-up observations of several objects can help to improve the characterization of these asteroids. This work explores the design of a solar-sail spacecraft for such a mission, focusing on the search of possible sequences of encounters and the trajectory optimization. This is done in two sequential steps: a sequence search by means of a simplified trajectory model and a set of heuristic rules based on astrodynamics, and a subsequent optimization phase. A shape-based approach for solar sailing has been developed and is used for the first phase. The effectiveness of the proposed approach is demonstrated through a fully optimized multiple near-Earth asteroid rendezvous mission. The results show that it is possible to visit five near-Earth asteroids within 10 years with near-term solar-sail technology.