26 research outputs found
Evaluating the consistency and discrepancies among biomass datasets in the Cornwall region through a comparative analysis of their methodologies and performance
No full textBiomass data is essential for environmental monitoring and management, but inconsistencies and uncertainties among these datasets hinder accurate estimates. This study comprehensively compares GEDI, ESA CCI, and ICESat-2 biomass datasets for Cornwall, an analysis not previously been conducted, evaluating spatial distribution, statistical properties, uncertainty, and saturation.
GEDI offers high-resolution, precise biomass estimates suitable for ecological studies, despite its coarser resolution compared to the other datasets. ESA CCI provides global coverage and integrates various data sources for climate change mitigation, but early signal saturation is an issue. ICESat-2 combines field measurements with satellite data, offering detailed temporal insights, but uncertainty is higher in Cornwall's complex landscape.
This analysis revealed significant biomass estimate variations due to sensor differences, methodologies, and processing techniques. GEDI and ICESat-2 captured broader biomass ranges compared to ESA CCI's predominantly lower values. Methodological transparency varies, although GEDI’s enhanced clarity is evident through precision categorisation. Lidar-based GEDI outperformed optical and radar methods such as those by ESA CCI, which saturated earlier. Resampling impacts are evident in altered statistical properties, with higher R-squared values indicating stronger large-scale relationships but reduced detail at coarser resolutions.
The importance of this research and its results lies in its potential to enhance the accuracy of biomass estimation and improved ecological research, land use planning, carbon accounting and climate change mitigation efforts. By examining the differences and complementarities between these datasets, this study supports more informed decision making in selecting appropriate data sources. Furthermore, the insights gained from this analysis can inform efforts in biomass mapping not only in Cornwall but also in other regions with similar ecological characteristics. To ensure biomass mapping produces comparable, reliable, and consistent results, user-friendly product documentation employing consistent terminology is strongly recommended
Air Traffic Control Advisory System for the Prevention of Bird Strikes
No full textBird strike prevention in civil aviation has traditionally focused on the airport perimeter. Since the risk of especially damaging bird strikes outside the airport boundaries is rising, this PhD thesis researches the safety potential of operational bird strike prevention involving pilots and controllers. In such a concept, controllers would be equipped with a bird strike advisory system, allowing them to delay departures which are most vulnerable to the consequences of bird strikes. However, the introduction of take-off delays reduces the maximum capacity of a runway. This PhD thesis investigates the feasibility of a bird strike advisory system with regard to safety and capacity by performing fast-time simulations including different air traffic intensities and bird abundance. In a first step, a system assuming perfect predictability of bird movement is developed, demonstrating a strong safety potential. However, when preventing all bird strikes, the induced delays can exceed tolerable limits for high air traffic intensities. In a second step, the system includes the limited predictability of bird movement. Bird tracks are predicted based on a simple linear regression model, considering variability of velocity and heading. To limit the negative effects on runway capacity, delays are only imposed on aircraft, for which strikes are predicted with a high probability and a damaging potential. The number and duration of delays remains reasonable even for airports operating at their capacity limits. However, linear regression proves insufficient to suitably evaluate the risk of collisions. To achieve reliable predictions, in-depth studies of multi-year bird movement data from various sensor types are recommended to develop site- and species-specific bird models. As such, the concept of a bird strike advisory system can be further developed to exploit the entire safety potential demonstrated by the initial study of the thesis.Control & Simulatio
Evaluating the Effects of a Bird Strike Advisory System
No full textBird strikes have operational impacts and cause economic loss to the aviation industry. In the worst case, the damages resulting from bird strikes lead to crashes. The highest risk for bird strikes is in the area below 3000 ft and thus mainly in airport environments. Despite intense efforts from the airports in controlling the local bird populations, the number of bird strikes in these environments is still very high. Usually, Air Traffic Control is neither integrated into the process for reducing bird strikes nor do the controllers receive any precise information about the current bird traffic situation at the airport. For the project described in this paper, we assume a different situation: Air Traffic Control is provided with a tool informing the controller about the current and predicted bird traffic at the airport. Based on this information, the controller can decide to delay departing air traffic in order to avoid potential collisions between birds and the aircraft taking off. When implementing this procedure at an airport, we expect an increase in airport safety and, due to the delaying of traffic, a reduction in runway capacity. We hypothesize, that the Relations between the settings of the alerting systems and the effects on safety and capacity are deterministic. To test this hypothesis, we will perform
fast-time simulations under varying conditions. This paper describes the simulation environment created for this purpose
URBAN AIR TRAFFIC MANAGEMENT FOR COLLISION AVOIDANCE WITH NON-COOPERATIVE AIRSPACE USERS
No full textWith the rise of new and innovative Urban Air Mobility solutions, there also arises a need to integrate these into the existing airspace. Current airspace users include conventional civil, commercial and general aviation, military air users, police and emergency services as well as a plethora of avian life. Planned additions to the airspace are electric vertical take-off and landing vehicles such as logistics drones and air taxis. The airspace for conventional users is stringently controlled. Urban Air Mobility operations are expected to mainly take place in individual corridors to be added to the currently uncontrolled low-level airspace. This airspace is also intended for various types of drone operations, out of which, small-scale drones can be non-co-operative. In addition, the operational altitudes of Urban Air Mobility aircraft will strongly expose them to birds. Due to abundance of these non-cooperating airspace users (like hobby-drones and birds), conflicts with Urban Air Mobility aircraft are expected to be inevitable. The aim of this paper is to develop a concept of Urban Air Mobility Collision Avoidance System to reduce the likelihood of collision between air taxis and non-cooperating airspace users. As such, this work proposes the introduction of an additional safety layer to prevent collisions during operations of strong exposure. The concept consists of a conflict detection and resolution method tailored for Urban Air Mobility operations. A three-dimensional safety envelope is designed using the geometric and performance values of the aircraft configurations currently available. Procedures to avoid conflicts prior to as well as during the flights are presented. Finally, the concept is visualized for the common use case of a shuttle service between an airport and a railway station. The results demonstrate the importance of incorporating individual aircraft configuration into conflict avoidance approach and report its effect to avoid collision.Control & Simulatio
Aircraft Performance for Open Air Traffic Simulations
No full textThe BlueSky Open Air Traffic Simulator developed by the Control \& Simulation section of TU Delft aims at supporting research for analysing Air Traffic Management concepts by providing an open source simulation platform. The goal of this study was to complement BlueSky with aircraft performance models in order to enable performance-related Air Traffic Management studies. The aircraft performance model developed within this work consists of a kinetic Flight Dynamics Model, which stores the required performance characteristics in a database with type-specific aircraft and engine coefficients. Currently, sixteen commercial turbofan and turboprop aircraft from different range and weight categories are represented. To evaluate the quality of the aircraft performance model, its outputs were compared to results from literature as well as from real flights. It was found that the applied methodologies for the determination of aircraft performance accurately model high-speed drag polars as well as fuel consumption for cruising and taxiing aircraft. The fuel consumption model of climbing and descending aircraft, however, leaves room for improvement. Possible strategies for obtaining a more precise estimation of fuel burn over the entire flight are recommended based on the results of this study. With this work, the BlueSky Open Air Traffic Simulator considers individual aircraft performance. This is an important step in the creation of an open simulation platform for Air Traffic Management research
ATC Advisory System for the Prevention of Bird Strikes
No full textCollisions between birds and aircraft, so called bird strikes, pose a considerable risk for aviation safety. Because risk of bird strike is highest below 3000ft, current mitigation measures mostly focus on keeping birds away from airport grounds. Despite these efforts, the number of bird strike occurrences is still significant. The PhD project presented in this poster evaluates a new approach for mitigating bird strike risk: Tower control is provided with information about the current and predicted bird traffic in the arrival and departure corridor. Based on the derived risk for collision, the controller can decide to reroute or delay traffic. The target of this PhD project is to determine the feasibility of such an approach by assessing the effects on safety and airport capacity when applying this concept
Detect to Avoid: Supporting Aviation Safety with Bird Movement Information
No full textThe presented research evaluates the concept of providing an airport’s Air Traffic Control with a bird strike advisory system. Such a system informs the controller about current and predicted bird movements in the arrival and departure corridors. Based on this information, the controller can decide to delay or reroute air traffic in order to prevent collisions with birds. To evaluate the resulting effects on the airport’s safety and capacity, fast-time simulations merging air traffic and bird movements, will be performed. To represent realistic bird movements, inputs from two different radar types are combined. For the close airport environment, historic bird tracks from avian radar installed at the considered airport serve as source. To cover the arrival and departure corridors up to 3000ft, the altitude up to which the largest majority of bird strikes occur, data from weather radar is used: based on bird densities and speed directions, bird tracks are generated for different altitude bands. The obtained tracks from avian and weather radar are combined in order to retrieve the overall image of bird movements in the close and extended airport area. This paper describes the methods for extracting, generating and finally combining the inputs from the two radar sources, in order to generate realistic bird movements. These will serve as a key input parameter for evaluating the effects of a bird strike advisory system with fast-time simulations.Control & Simulatio
What is the Potential of a Bird Strike Advisory System?
No full textThis paper presents a collision avoidance algorithm to prevent bird strikes for aircraft departing from an airport. By using trajectory-information of aircraft and birds, the algorithm predicts potential collisions. Collision avoidance is performed by delaying departing aircraft until they can follow a collision-free trajectory. An implementation of this concept has the potential to increase aviation safety by preventing bird strikes but might reduce runway capacity due to delaying aircraft. As a precursor to the feasibility, this study investigates the maximum achievable safety effect at minimum delay costs of such a system by assuming a deterministic world. Therefore, no uncertainties regarding bird and aircraft positions were considered to enable the system to prevent all bird strikes for departing traffic while causing the smallest possible delay. The anticipated effects were studied by running fast-time simulations including three air traffic intensities at a single-runway airport and bird movements from all seasons. The results imply a high potential for the increase in safety at a
reasonable reduction in runway capacity. An initial cost-estimate even revealed a strong saving potential for the airlines. Based on these results, a feasibility study of implementing a bird strike advisory system including uncertainties in bird movements as well as probabilistic effects will be performed
Simulating the Risk of Bird Strikes
No full textThis paper presents a fast-time simulation environment
for assessing the risk of bird strikes in aviation. An existing air traffic simulator was enhanced in order to simulate air and bird traffic simultaneously and to recognize collisions between birds and aircraft. Furthermore, a method was
developed to generate bird movement information from different radar sources. The resulting set-up represents the first simulation environment to perform fast-time simulations including air traffic and bird movements. A verification with real data revealed that approximately thrice as many bird strikes occur in the simulation as in reality. When considering bird reaction to approaching
aircraft, which is not covered in the simulation as well as
unreported strikes, this implies an adequate result. For this
reason, the simulator can serve as valuable tool to analyse the risk of bird strikes and to evaluate new Air Traffic Management concepts to reduce the number of these events
Robust large area molecular junctions of selfassembled monolayers of a model helical paddlewheel complex
No full textThe author acknowledge support from the Universidad Complutense de Madrid (GRFN32/23, GRFN24/24 and project PR3/23-30828), the France 2030 government investment plan managed by the French National Research Agency under grant reference PEPR SPIN – SPINMAT ANR-22-EXSP-0007, the Imperial College – CNRS joint PhD program, Quantum Matter Bordeaux, the MaelStroM project (CNRS MITI program), the National Research Agency project AnaCrU-CISS (ANR-23-CE09-0026) and the GPR Light project LIGHT-057-ChiroSurf. I.C. acknowledges predoctoral grant from the Complutense University of Madrid and Banco Santander (CT82/20-CT83/20). The authors warmly thank J.P. Salvetat of the Placamat service unit (France) for the ToF-SIMS measurements and Stéphane Toulin for assistance with the open data repository. Computer time for the theoretical calculation was provided by the computing facilities MCIA (Mésocentre de Calcul Intensif
Aquitain) of the Université de Bordeaux.We report the preparation of a helical complex and its study in molecular junctions. We show that the SAMs of this racemic compound present an electrically robust behaviour which will pave the way for future studies of the CISS effect with analogous enantiopure compounds.Universidad Complutense de MadridAgence Nationale de la Recherche (France)Imperial CollegeBanco SantanderUniversité de BordeauxDepto. de Química InorgánicaFac. de Ciencias QuímicasTRUEpu
