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Rapid identification of disaster hotspots by means of a geospatial information fusion from remote sensing and social media
Get PDFEffective management of complex disaster scenarios relies on achieving comprehensive situational awareness. Recent disasters, such as the 2024 floods in Southern Germany, have highlighted the critical need for timely geoinformation to protect communities. During the response phase, it is vital to rapidly identify the most affected areas to guide emergency actions and allocate limited resources effectively. This process is typically iterative, incorporating continuous updates as new or improved information becomes available. Initial estimates, often based on incomplete or imprecise data, play a crucial role in forming an early situational overview before detailed damage assessments are conducted. Early-stage proxies, such as population distribution and hazard zones, can support planning data collection efforts, enhancing situational understanding and focusing response efforts efficiently.
This study introduces a method for rapidly identifying disaster hotspots, particularly in scenarios where detailed damage assessments or very high-resolution satellite imagery are not (yet) available. The approach leverages the H3 discrete global grid system and employs a log-linear probability pooling method with an unsupervised hyperparameter optimization routine. It integrates flood hazard data from systematically acquiring high-resolution satellite imagery (Sentinel-1 and Sentinel-2), disaster-related information from X (formerly Twitter), and freely accessible geospatial data on exposed assets. The methods effectiveness is assessed by comparing its outputs to detailed damage assessments from five real-world flood events (USA August 2017, Mozambique 2019, Mexico November 2020, Germany July 2021, Pakistan September 2022). Results demonstrate that disaster hotspots can be identified using readily available proxy data.
An extensive hyperparameter analysis revealed that while equal-weight methods offer simplicity and effectiveness, optimized pooling weights generally yield superior results. Context-specific tuning was shown to be critical for optimal performance in log-linear pooling. Notably, an unsupervised method minimizing the Kullback-Leibler divergence between input distributions and predictions outperformed supervised approaches, overcoming the limitations of training data. This method’s transparency and adaptability allow it to incorporate geospatial layers with varying resolutions and semantic relevance, making it particularly suitable application to other hazards (e.g., landslides, wildfires, earthquakes) or exposed assets (e.g., roads, railways, critical infrastructure)
Design of a shape-adaptive rotor for the reduction of BLI induced losses in the distorted flow regimes of a scaled turbofan fan rotor
No full textWithin the Cluster of Excellence for Sustainable and Energy-Efficient Aviation SE2A, a blended wing body aircraft is investigated to improve efficiency and carbon emissions of future air transport. By embedding the aircraft engines on the top rear fuselage, parts of the aircraft’s wing boundary layer are ingested, which has the potential to further improve the engine’s propulsion efficiency. Through the ingestion of low momentum fluid, inflow distortion is induced and the fan rotor operates under increased flow incidence, when passing through the distorted flow regimes. To reduce the thereby arising efficiency and pressure ratio penalties in the aircraft engine, alternative design strategies for the fan stage are required. Within this investigation, an active shape morphing mechanism is introduced, which allows to temporarily adjust the fan blading when the fan rotor is exposed to distorted inflow conditions. By integrating piezoceramic actuators into the rotor blading, the blade staggering and turning can be adjusted with the goal to reduce flow incidence and deviation in the distorted flow regimes. For this investigation, the NASA rotor 67 is chosen as an initial test case and its performance under boundary layer ingestion (BLI) conditions is evaluated. For the shape morphing assessment, FEA morphing simulations are coupled with stationary CFD simulations of the actuated fan rotor geometries under distorted inflow. As the achievable deformations for the NASA rotor 67 are however too small to compensate for the strong distortion effects, a fan re-design is conducted. The re-design follows current ultra-high-bypass-ratio (UHBR) fan concepts with a particular focus on the shape-morphing capability of the rotor. Within this investigation the focus especially lies on three-dimensional design adaptions, such as a hub chord reduction as well as dihedral and sweep. By considering carbon fiber reinforced polymers (CFRP) as blade material, the impact of tailored blade architectures on the morphing behavior is additionally considered
IDEFIX - The MMX Rover: one Year before Launch
No full textThe Martian Moon eXploration (MMX) mission by the Japan Aerospace Exploration Agency, JAXA, is going to explore the martian moons Phobos and Deimos. Both moons will be investigated remotely from the mother spacecraft, that will also collect samples from the surface of Phobos, as well as by a small rover, IDEFIX, that will be delivered to Phobos surface and make in-situ investigations. The Rover carries a scientific payload of four instruments: RAX, a Raman spectrometer to measure the mineralogical composition of the surface material, NavCam, a stereo pair of cameras looking ahead to image the terrain and also support navigation, miniRAD a radiometer measuring the surface brightness temperature of both regolith and rocks, and two WheelCams looking at the wheel-surface interface, and thus investigating the properties and dynamics of the regolith. The cameras, will serve for both, technological and scientific needs. Landing of the rover is foreseen for late 2028 or early 2029 after a landing site selection process, considering technical and scientific aspects. The delivery will take place in context with the rehearsal of the first landing operations of the main spacecraft. IDEFIX will be released from an altitude of about 40 m, fall to the surface, upright itself and drive and carry out scientific investigations for about 100 days. The flight model of the rover is at JAXA/MELCO, integrated to the main MMX spacecraft and finalizing qualification and functional tests. Operational sequences, e.g. defining the interplay between locomotion and science instruments are currently prepared at the two Rover Control Centers, at CNES in Toulouse and DLR in Cologne. Launch of the MMX mission is planned for October 2026 from the Tanegashima Space Center in Japan. The Rover is a contribution by the Centre National d’Etudes Spatiales (CNES) and the German Aerospace Center (DLR) with additional contributions from INTA and Univ. Valladolid (Spain) and Univ. Tokyo and JAXA
Detection of visible-wavelength aurora on Mars
Get PDFMars hosts various auroral processes despite the planet’s tenuous atmosphere and lack of a global magnetic field. To date, all aurora observations have been at ultraviolet wavelengths from orbit. We describe the discovery of green visible-wavelength aurora, originating from the atomic oxygen line at 557.7 nanometers, detected with the SuperCam and Mastcam-Z instruments on the Mars 2020 Perseverance rover. Near–real-time simulations of a Mars-directed coronal mass ejection (CME) provided sufficient lead-time to schedule an observation with the rover. The emission was observed 3 days after the CME eruption, suggesting that the aurora was induced by particles accelerated by the moving shock front. To our knowledge, detection of aurora from a planetary surface other than Earth has never been reported, nor has visible aurora been observed at Mars. This detection demonstrates that auroral forecasting at Mars is possible, and that during events with higher particle precipitation, or under less dusty atmospheric conditions, aurorae will be visible to future astronauts
Of networks and regularization: new developments in Lagrangian Particle Tracking
Get PDFThis talk will introduce several recent developments in the the field of 3D particle tracking and related post-processing methods. The aspects that will be touched are: (i) Machine-learning based dectection of particle images and the implications for 3D position reconstruction. (ii) First experiences with high-performance-computing evaluations using the Shake-The-Box algorithm. (iii) Comparisons of several classes of flowfield-reconstruction approaches (Binning, Data Assimilation, Physics-Informed Neural Networks)
Forschung zu militärischen Triebwerkstechnologien
No full textDer Vortrag, der am Bildungszentrum der Bundeswehr gehalten wurde, beinhaltet einen Überblick über die Schwerpunkte der militärischen Triebwerksforschung im DLR. Die vorgestellten Ergebnisse stammen aus den DLR Projekten Future Fighter Engine Technologies (FFE und FFE+) und Future Fighter Engine Evolution (FFE2). Es umfasst folgende Themen: Variable Cycle Engine, Thermal Management System, 3D-CFD, Triebwerksintegration, CMC, neuartige Werkstoffe und Fertigungsverfahren von Turbinenschaufeln und neuartige Kühlungskonzepte
Advancing high-pressure turbine vane cooling through additive manufacturing: Insights from the 3DCeraTURB project
No full textThe efficiency of modern gas turbines and jet engines is closely tied to the permissible operating temperatures of the materials used. As the inlet temperature of high-pressure turbines rises, the need for advanced cooling techniques becomes critical, demanding the development of robust materials and innovative fabrication methods. Key challenges in designing these cooling systems include achieving uniform airflow distribution, reducing temperature gradients, and optimizing cooling according to load zones, all while adhering to manufacturing and strength constraints.
Research at the German Aerospace center aims at furthering and exploiting additive manufacturing (AM) technologies to addresses these challenges by developing turbine vanes with intricate cooling structures suited particularly for fabrication with Laser Powder Bed Fusion (LPBF). In the highly interdisciplinary 3DCeraTurb project, new designs are being developed, LPBF materials studied and turbine vane demonstrators realized and tested. These demonstrators feature double-wall pins and an array of holes and film cooling holes. The aim is to achieve a more efficient cooling to enhance engine performance and enable fuel savings and emission reductions.
This talk summarizes the progress of 3DCeraTurb with a focus on the additive manufacturing process developments and materials studies. Beyond the production of advanced turbine vanes, the project has enabled enhancements across the production chain, including heat treatment, mechanical property optimization, and post-processing of surfaces. Different materials suited well for laser welding-related processed including Inconel 718 and VDM780 are being investigated. Inconel 718 is readily available at low cost, well understood and can be processed robust and reproducibly, but to pave the way for better high-temperature performance materials, new alloys such as VDM780 that can potentially withstand temperatures up to 750 °C under fatigue and creep conditions need to be considered. 3DCeraTurb marks a significant step toward in exploiting additive manufacturing for enhancing turbine efficiency and reliability in extreme operating environment
Estimating solar-radiation environment extremes
Get PDFContext. Extreme solar particle events (ESPEs) were identified almost a decade ago, providing context for super events unleashed by our host star, the Sun. Their assumed solar origin drives the question of their "worst-case" impact, which could be profound, multifaceted, and devastating for our technological society. Aims. Recently, we proposed a methodology that directly relates the soft X-ray flux (FSXR) of the driving solar flare of a solar energetic particle (SEP) event to its "worst-case" integral fluence spectrum. In this study, we aim to put the letter to the stress test. Methods. In this study, we employed our previous method to the ESPEs that have been confirmed in cosmogenic radionuclide records to date, retrieved their "worst-case integral spectrum, and compared the latter to the actual – independently obtained – recent reconstructions based on the radionuclide records. Results. It is shown that our previous method makes it possible to estimate the integral fluence spectra of one of the paleo events, that is, AD774/775, one of the strongest ESPEs found within the cosmogenic radionuclide records so far. We implemented a mean ESPE utilizing four confirmed paleo ESPEs (i.e., AD993/994, AD774/775, 660 BCE, and 7176 BCE) and tested the resulting spectrum against the estimated one. Finally, we tested the same methodology for a series of strong SEP events recorded on the Earth's surface as ground level enhancement (GLE) events. In all investigated cases, a recent re-calibration of the GOES 1–8 FSXR values is considered. Conclusions. It is shown that the proposed methodology can adequately estimate the "worst-case" integral fluence spectrum for both strong SEP events and ESPEs, quantifying their impact up to an integral energy of ∼E > 1 GeV
Parallax and cloud shadow correction in satellite-based solar irradiance estimation: A study in tropical environments
Get PDFAccurate estimation of Global horizontal solar irradiance (GHI) from geostationary satellite imagery is essential for intraday solar PV power forecasting. Tropical regions show an even more challenging situation: A typically much higher tropopause results in higher cloud tops and correspondingly larger parallax errors in satellite imagery with significantly larger cloud shadow displacements compared to mid-latitudes. This study improves GHI estimates from Meteosat-8 by correcting cloud parallax and shadow displacement using gridded cloud top height (CTH) data. Fractional or sub-pixel displacement of individual cloudy pixels is enabled by bilinear interpolation in contrast to prior methods that allowed only integer shifts or assigned a single CTH value to a grouping of adjacent cloud pixels. Validation against one year of 15-min resolution ground-based measurements at five sites in South and Southeast Asia shows a reduction in relative root mean square error (rel. RMSE) from 23.8 % to 22.1 %. Improvements are more pronounced at higher satellite viewing zenith angles and in the presence of high-altitude clouds. The corrected satellite-based GHI exhibits 4–7 percentage points lower rel. RMSE than National Solar Radiation Database (NSRDB) and 2.5 points lower than CAMS solar radiation service for similar
viewing zenith angles. Greatest error reductions occur during partly cloudy conditions for sites within 61° viewing zenith angle, and under overcast skies for sites close to the edge of Meteosat-8's field of view. Improvements also depend on the co-scattering angle between sun and satellite with respect to the site, and the availability of sufficient upstream cloud information along the path of solar irradiance falling on the site. Ramp detection accuracy improves, particularly at lower detection thresholds, as measured using the Swinging Door Algorithm