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Intersection Planning in Multilane Aerial Corridors for UAVs
No full textUncrewed aerial vehicles (UAVs) are revolutionizing traditional aviation markets by opening the airspace to new participants and expanding multimodal applications, increasing the UAVs' participation in the uncontrolled low-altitude class G airspace. Therefore, having a UAV Traffic Management (UTM) system is of great importance in designing structured traffic rules for UAV paths in the airspace (corridors) and intersections. This work addresses the problem of intersection planning in the context of UTM. We consider a multilane multi-UAV traffic management framework, CORRIDRONE. In this setup, an intersection volume is defined when two or more multilane corridors merge in the airspace. Unlike road intersection scenarios, an aerial intersection has a virtual, non-visible boundary. Hence, resolving conflicts is challenging without a traffic light. In this thesis, we develop algorithms to manage intersections and resolve conflicts in pre-flight and in-flight modes. In the first part of the thesis, we consider that only one UAV is assigned per corridor. Hence, intersection volumes are created by intersecting two lanes. Here, we present an algorithm that exploits the relative geometry between the UAVs and schedules the speed of one UAV relative to the other for multiple intersections. Next, we extend this methodology to pre-plan a UAV trajectory also to include UAV accelerations while scheduling. This method utilizes the time taken for the UAVs involved in the conflict to enter and exit an intersection formed owing to their corridor paths. For corridors with multiple lanes, we define an intersection volume free of lanes, such that the lane boundaries are valid only till the intersection boundaries. We then present a lane-changing approach to resolve conflicts by changing the initially intended path connecting two lanes. We further added security to the UAVs in conflict-laden scenarios by creating a dronecage, which is an amalgamation of multiple geofences intersecting at multiple points (intercrosses). The UAVs travel inside these geofences to change lanes or corridors and reach their destination safely. We propose an algorithm that uses an approach vector-based strategy to navigate this dronecage. We show the effectiveness of the algorithms developed with numerical simulations and hardware tests. The motivation behind the thesis lies in providing the complete conflict resolution architecture for UTM to be used if and when needed in real-life scenarios
Phase Space Deep Neural Network with Saliency-Based Attention for Hyperspectral Target Detection
No full textThe accurate separation of targets and background is challenging in hyperspectral target detection algorithms, due to the high variability and complex non-linear scattering interactions in spectra acquired by imaging spectrometers. Moreover, the target regions may be contaminated by the background signal in real images, hindering the separation of a specific target in a scene. To address these challenges, a deep neural network is proposed in this work, consisting of three modules. First, to extract features hidden in the spectral signature of pixels, the hyperspectral image is considered as a dynamic system, and its phase space is reconstructed in the spectral feature space. Subsequently, in order to highlight the targets and suppress the background, a saliency map is produced, which shows candidate regions for the targets of interest. The saliency map is then utilized as an attention map for weighting the hyperspectral input within the network. The proposed multi-branch deep neural network processes each dimension of the reconstructed phase space. The resulting Phase Space Deep Neural Network with Saliency-based Attention (PSDNN-SA) outperforms several state-of-the-art detectors both quantitatively and visually in experiments carried out on different real hyperspectral subsets
The influence of surface imperfections on boundary layer transition. Measurements and perspectives
No full textA summary of the experiments performed in KRG and HDG via TSP
Der Einsatz von Erdbeobachtungsdaten im Rahmen des Katastrophenmanagements von Hochwasserereignissen
No full textLarge-scale reorientation in cubic Rayleigh–Bénard convection measuredwith particle tracking velocimetry
Get PDFThree-dimensional velocity fields of a large-scale reorientation in turbulent Rayleigh–Bénard convection at Ra = 2.5 · 10 9 in a 300 mm cubic water cell are measured using particle tracking velocimetry. Reorientations are rare events occurring about once every three days in our setup, involve the large-scale circulation switching between cell diagonals. The dominant flow structures of the reorientation are extracted from the measurement data using POD supported by symmetries of the cubic cell to mimic long time series of reorientation events. The decomposition reveals degenerate mode pairs. The first six modes of the decomposition account for about 70% of the total energy and contain the major coherent structures. Modes 1-3 reflect the orientation and dynamics of the large-scale circulation, and modes 4-6 provide the orientation and dynamics of the corner circulations. A pure Y roll structure is observed in the middle of the reorientation event
Quantum gravimetry for future satellite gradiometry
Get PDFThe present electrostatic accelerometers (EA) drift at low frequencies. To address this problem, integrating a cold atom interferometry(CAI) accelerometer could be beneficial, as it offers the potential for superior long-term stability. The CAI-based accelerometers (CAI ACC) are accurate and stable, but they have some issues with long dead times and a relatively small dynamic range. A way to address these problems is to combine a CAI ACC with an EA in a hybrid configuration. Using CAI ACC in an upcoming satellite gradiometry mission can give stable and accurate measurements of the static Earth's gravity field. Three scenarios have been considered in this study: first, a realistic scenario involving current-generation and realistic hybrid accelerometers; second, a semi-realistic scenario with the same accelerometers and an accurate gyroscope; and third, using highly accurate hybrid/CAI accelerometers with an optimistic gyroscope. One significant aspect was on detecting temporal gravity changes, which cannot compare to the effectiveness of the low-low satellite-to-satellite tracking (LLSST) principle. But, quantum gradiometers can significantly enhance solutions for the static gravity field, provided one has accurate observations of the satellite orientation available
Automated Generation of Urban Medium-voltage Grids using OpenStreetMap Data
Get PDFRealistic geo-referenced electrical distribution grid (DG) models are of great importance for power system analysis and resilience studies. However, DG data are usually not publicly available. In this study, we develop a new process for the automated generation of medium-voltage (MV) grid topologies, specifically for urban areas, based on openly available data and open-source software. OpenStreetMap (OSM) data on power infrastructure, street layouts, and land use, are used as the only input source. In contrast to previous works on DG reconstruction, we use available OSM data on substation locations. Different existing methods are combined in a new, hybrid approach by considering the incompleteness of OSM data, taking the street network into account, and applying the Capacitated vehicle routing problem (CVRP) to find cost-optimal routes for power lines. Our method is tested with a German city as a case study. Furthermore, we verify the result using land use data and evaluate the quality of power-related OSM data. The results demonstrate that our approach can yield realistic geo-referenced MV grid topologies, even with incomplete OSM power data
Aligning heat pump operation with market signals: A win-win scenario for the electricity market and its actors?
Get PDFResidential heat pumps (HPs) have a promising technical potential for demand response. Real-time pricing (RTP) schemes are currently emerging in many countries to unlock this potential. This study is the first to assess the comprehensive efficacy and appeal of incentivizing flexible HP usage with RTP by integrating the perspectives of the energy market and its actors. To this end, we have coupled an agent-based model of the German electricity market with a bottom-up residential HP dispatch optimization model. Our study identifies potential win-win scenarios for the market and its actors in specific contexts. This is particularly the case when users with local photovoltaic or energy-efficient buildings operate HPs with RTP and have moderate comfort tolerance regarding flexible heating setpoints. In these instances, users can realize savings of 10–30 % of annual costs, while market actors benefit from a modest reduction in the maximum residual load (3–5 GW by 2040) and an increase in market values for wind energy. In other contexts, there may be unintended consequences. This is especially relevant when intense responses to price signals due to a high user comfort tolerance cause overshoots in flexible demand, thus triggering an "avalanche effect." In such cases, new residual load peaks emerge compared to inflexible HP operation. Moreover, users in many building types then no longer benefit from flexible HP usage with RTP, as associated expenses such as aggregator fees paid to offset the avalanche effect at the day-ahead market diminish the electricity cost savings. In light of the potential drawbacks for the electricity market and users, our study highlights the importance of conducting a thorough assessment before implementing RTP for flexible HPs on a large scale