Space debris growth and an influx in space traffic will create a need for increased space traffic management. Due to orbital population density and likely future growth, the implementation of a slot architecture to Sun-synchronous orbit is considered in order to mitigate conjunctions among active satellites. This paper furthers work done in Sun-synchronous orbit slot architecture design and focuses on two main aspects. First, an in-depth relative motion analysis of satellites with respect to their assigned slots is presented. Then, a method for developing a slot architecture from a specific set of user defined inputs is derived.

Diplomová práce se zabývá jednak popisem stavu letecké dopravy a to zejména co se týče její bezpečnosti, plynulosti, propustnosti a kapacity. Výše uvedené je poté zhodnoceno v části věnující se aspektům nebezpečnosti vzdušného prostoru v jednotlivých fázích letu.

Purpose - This bachelor thesis compares high-speed rail (HSR) transport with air transport. The investigation considers physical fundamentals, energy consumption, environmental impact, infrastructure and investment, market situations, passenger's selection criteria to choose transportation options, and overall economics. --- Methodology - The thesis combines an investigation of physical principles with a literature review. --- Findings - Steel wheels on steel rails show by far less rolling resistance to support the train's weight than drag due to lift (induced drag) to support the aircraft's weight. This leads to less energy consumption. HSR trains use electricity from an overhead line. Hence, the environmental impact of HSR also depends much on how the electricity is produced. Airplanes only need an air traffic control environment to connect airports. In contrast, HSR needs infrastructure to connect stations. The amount of necessary infrastructure depends on the geological conditions. For example, crossing mountains means high investment. Longer passages over water are infeasible for HSR. High-speed rail is superior to air transport when connecting megacities because the trains have higher transport capacity, offer higher service frequencies and mission reliability, shorter total travel time, shorter access time to stations, shorter unproductive waiting time in stations and potentially lower travel costs. HSR is a strong competitor to airline services and has replaced some short range flights. A comparison of HSR in different world regions shows differences in the market situation and in passenger's selection criteria for transportation options. --- Research limitations - The potential of high-speed rail was investigated mainly on busy routes with high service frequencies. A comprehensive network comparison between high-speed trains and airplanes was not done and could lead to somewhat different results. --- Practical implications - The report tries to contribute arguments to the discussion about alternatives to air travel. --- Social implications - With more knowledge people can make an educated choice between transport options, can vote with their feet, and can take a firm position in the public discussion. --- Originality/value - A general comparison of HSR and air transport from physical fundamentals to economics seemed to be missing.

En modernisering av Air Traffic Management pågår för att hållbart hantera den förutsedda ökningen av flygtrafik fram till år 2035. Som en del av denna modernisering har Saab AB utvecklat en produkt, “Digital Tower”, som möjliggör att flygtorn kan fjärrstyras genom ett system av kameror. I syfte om att öka kunskap kring flygledarnas behov och flygsäkerhet i takt med ökad mängd flygtrafik, har denna studie undersökt den kognitiva belastningen inom den operativa miljön av en Digital Tower som är i bruk. I dess nuvarande form har interaktiva gränssnitt inom arbetsmiljön begränsad flexibilitet och anpassningsmöjligheter. Frågeställningen har därför ställts kring hur dessa begränsade anpassningsmöjligheter påverkar flygledares arbete och samarbete. Studien har utgått ifrån en kvalitativ metodik, en contextual inquiry med observationer och intervjuer i kontext där arbetet skedde. Analysen gjordes utifrån Distributed Cognition som teoretiskt ramverk, vilket möjliggjorde en analys av den distribuerade kognitionen mellan aktörer och hur de brukar artefakter inom kontexten. Studiens slutsats är att gränssnittets begränsade anpassningsmöjligheter påverkar den kognitiva belastningen negativt, men anses inte som ett hinder för flygledarnas arbete. Eftersom den centraliserade arbetsmiljön har en stark närvaro av kollegor, har resultatet blivit att kollegorna kan kompensera för gränssnittets brister och avlasta i situationer av hög arbetsbelastning. / An ongoing modernization of Air Traffic Management is in effect to keep up with the forecasted increase in air traffic by 2035. As a part of this modernization a product was developed by Saab AB to control air traffic from remote control towers with a system of cameras, called “Digital Tower”. With the purpose of increasing the knowledge about the needs of Air Traffic Controllers and general flight safety with increased amount of flight traffic, this study researched the cognitive load within the operative Digital Tower environment in service. Currently the interactive interface within the work environment has limited flexibility and possibilities for adaptation. The study has therefore answered the question about how these limited adaptations affect the Air Traffic Controllers work and collaboration between them. The study has used qualitative methods in order to answer the question, by using a contextual inquiry which includes observations and interviews of the Air Traffic Controllers in their context. The result was analyzed by using Distributed Cognition theory, which made it possible to analyze the distributed cognition between people and artifacts within the context. The conclusion of the study is that the limited adaptations of the interface negatively affects the cognitive load, but has not been identified as a crucial interference for the Air Traffic Controllers. The centralized work environment has a strong presence of colleagues, which has led to the colleagues compensating for the limited interface by physically unburden the workload in critical situations.

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<p>In this thesis the problem of multitarget tracking in multistatic sensor networks is studied. This thesis focuses on tracking airborne targets by utilizing transmitters of opportunity in the surveillance region. Passive Coherent Location (PCL) system, which uses existing commercial signals (e.g., FM broadcast, digital TV) as the illuminators of opportunity for target tracking, is an emerging technology in air defence systems. PCL systems have many advantages over conventional radar systems such as low cost, covert operation and low vulnerability to electronic counter measures.</p> <p>One of another opportunistic signals available in the surveillance region is multipath signal. In this thesis, the multipath target return signals from distinct propagation modes that are resolvable by the receiver are exploited. When resolved multipath returns are not utilized within the tracker, i.e., discarded as clutter, potential information conveyed by the multipath detections of the same target is wasted. In this case, spurious tracks are formed using target-originated multipath measurements, but with an incorrect propagation mode assumption. Integrating multipath information into the tracker (and not discarding it) can help improve the accuracy of tracking and reduce the number of false tracks.</p> <p>In this thesis, these opportunistic measurements, i.e., commercial broadcast signals measurements in PCL tracking and resolvable multipath target return measurements in multipath assisted tracking are exploited. We give the optimal formulations for all of the above problems as well as the performance evaluations using PCRLB. Simulation results illustrate the performance of the algorithms.</p> / Doctor of Philosophy (PhD)

<p dir="ltr">The absence or limited availability of operational statistics at general aviation airports restricts airport managers and operators from assessing comprehensive operational data. The traditional manual compilation of operational statistics is labor-intensive and lacks the depth and accuracy to depict a holistic picture of a general aviation airport’s operations. This research developed a reliable and efficient approach to address the problem by providing a comprehensive and versatile flight status identification framework. </p><p dir="ltr">Leveraging the BlueSky flight simulation module, the research can generate a synthetic flight database to emulate real-world general aviation aircraft’s flight scenarios. Two neural network architectures, namely, an RNN-GAN network and a refined Seq2Seq network, were explored to examine their capability to reconstruct flight trajectories. The Seq2Seq network, which demonstrated better performance, was further employed to estimate the simulated aircraft’s different metrics, such as internal mechanical metrics and flight phase. Additionally, this research undertook an array of diverse tailored evaluation techniques to assess the efficacy of flight status predictions and conducted comparative analyses between various configurations. </p><p dir="ltr">Furthermore, the research concluded by discussing the future development of the framework, emphasizing its potential for generalization across various flight data applications and scenarios. The enhanced methodology for collecting operational statistics and the analysis tool will enable airport managers and regulators to better receive a comprehensive view of the airport’s operations, facilitating airport planning and development.</p>

Plus d’un quart de siècle après la chute du Mur de Berlin, la radicalité des changements politiques et économiques, caractérisés par l’intégration dans l’économie-monde et l’Union européenne, ainsi que par la récente montée du nationalisme, continue à poser des questions quant au devenir de l’espace centre-est européen. Ce contexte amène à appréhender dans ce travail l’effet de ces bouleversements au prisme des villes et de leurs évolutions. Trois forces majeures ayant guidé les transformations en Europe centrale et orientale sont examinées depuis 1989 : l’européanisation, la mondialisation et le changement endogène – relevant des traces du passé. Les dynamiques respectives de ces trois forces sont évaluées au moyen d’une approche interurbaine. Les échanges économiques entre villes centre-est européennes et celles du reste du monde sont examinés au travers de réseaux transnationaux et mondialisés – de transport aérien et de firmes. Ces échanges sont confrontés aux réseaux commerciaux entre pays. Cette thèse contribue à montrer que l’intégration à l’économie-monde s’est accompagnée d’un renforcement des logiques de polarisation divisant l’espace centre-est européen entre le Nord-Ouest et le Sud-Est. Cette intégration en cours, ou plutôt ces différentes « intégrations », ne se sont toutefois pas opérées uniquement au profit des métropoles. En effet, malgré une prédominance de l’européanisation, les liens de l’époque communiste constituent une force économique majeure pour certaines petites et moyennes villes – à l’image de l’entre-deux historique de l’espace centre-est européen. / A quarter of century after the fall of the Berlin Wall, radical political and economic changes, integration into the world economy and the European Union, and the recent reinforcement of nationalism are still persistent subjects of debate with regards to the future of Central and Eastern Europe. This thesis examines three major transformative forces in Central and Eastern Europe since 1989 at city-level: europeanisation, globalization and endogenous changes – related to path dependence effects. The dynamics of these three forces are analyzed by looking at the evolution of economic exchanges of CEE cities with other worldwide cities in the context of transnational and globalized networks – air traffic and firms. They are confronted with trade networks at country level. This dissertation illustrates that integration into the world-economy has deepened polarization in Central and Eastern Europe between the Nord-West and the South-West. This integration process or different types of integration are not only a matter for big cities and metropolises. In spite of the predominance of europeanisation, links from the communist period continue to be a major economic force, especially for small and medium-sized cities, reflecting the historical in-between situation of Central and Eastern Europe. / Ćwierć wieku później, radykalne zmiany polityczne i gospodarcze po upadku Muru Berlińskiego, integracja z gospodarką światową, przystąpienie do Unii Europejskiej oraz nasilające się tendencje nacjonalistyczne są wciąż bieżącymi tematami w dyskusji o przyszłości Europy Środkowo-Wschodniej. W tym kontekście, dysertacja proponuje analizę zmian systemowych, które dokonały się w regionie na poziomie miast. Przedmiotem badania są trzy procesy towarzyszące transformacjom po 1989: europeizacja, globalizacja oraz przemiany w regionie uwarunkowane relacjami z przeszłości. Dynamika wymienionych trzech procesów zostanie zbadana w odniesieniu do wymian ekonomicznych między miastami Europy Środkowo-Wschodniej a innymi miastami Europy i świata w sferze międzynarodowych powiązań lotniczych i firmowych, porównanych z siecią handlową ukształtowaną między państwami regionu. Wnioski badawcze wykazują, że w rezultacie integracji z gospodarką światową pogłębia się polaryzacja przestrzeni Europy Środkowo-Wschodniej w układzie północny zachód i południowy wschód. Różnorodność typów integracji odnosi się nie tylko do metropolii i dużych miast. Wobec dominującej siły europeizacji, powiązania z miastami z czasów komunistycznych są nadal ważnym aspektem funkcjonowania miast małych i średnich, ilustrując zarazem historyczną sytuację entre-deux Europy Środkowo-Wschodniej.

Air traffic flow management is a critical component of air transport operations because at some point in time, often very frequently, one of more of the critical resources in the air transportation network has significantly reduced capacity, resulting in congestion and delay for airlines and other entities and individuals who use the network. Typically, these “bottlenecks” are noticed at a given airport or terminal area, but they also occur in en route airspace. The two-stage combinatorial optimization framework for air traffic flow management under constrained capacity that is presented in this thesis, represents a important step towards the full consideration of the combinatorial nature of air traffic flow management decision that is often ignored or dealt with via priority-based schemes. It also illustrates the similarities between two traffic flow management problems that heretofore were considered to be quite distinct. The runway systems at major airports are highly constrained resources. From the perspective of arrivals, unnecessary delays and emissions may occur during peak periods when one or more runways at an airport are in great demand while other runways at the same airport are operating under their capacity. The primary cause of this imbalance in runway utilization is that the traffic flow into and out of the terminal areas is asymmetric (as a result of airline scheduling practices), and arrivals are typically assigned to the runway nearest the fix through which they enter the terminal areas. From the perspective of departures, delays and emissions occur because arrivals take precedence over departures with regard to the utilization of runways (despite the absence of binding safety constraints), and because arrival trajectories often include level segments that ensure “procedural separation” from arriving traffic while planes are not allowed to climb unrestricted along the most direct path to their destination. Similar to the runway systems, the terminal radar approach control facilities (TRACON) boundary fixes are also constrained resources of the terminal airspace. Because some arrival traffic from different airports merges at an arrival fix, a queue for the terminal areas generally starts to form at the arrival fix, which are caused by delays due to heavy arriving traffic streams. The arrivals must then absorb these delays by path stretching and adjusting their speed, resulting in unplanned fuel consumption. However, these delays are often not distributed evenly. As a result, some arrival fixes experience severe delays while, similar to the runway systems, the other arrival fixes might experience no delays at all. The goal of this thesis is to develop a combined optimization approach for terminal airspace flow management that assigns a TRACON boundary fix and a runway to each flight while minimizing the required fuel burn and emissions. The approach lessens the severity of terminal capacity shortage caused by and imbalance of traffic demand by shunting flights from current positions to alternate runways. This is done by considering every possible path combination. To attempt to solve the congestion of the terminal airspace at both runways and arrival fixes, this research focuses on two sequential optimizations. The fix assignments are dealt with by considering, simultaneously, the capacity constraints of fixes and runways as well as the fuel consumption and emissions of each flight. The research also develops runway assignments with runway scheduling such that the total emissions produced in the terminal area and on the airport surface are minimized. The two-stage sequential framework is also extended to en route airspace. When en route airspace loses its capacity for any reason, e.g. severe weather condition, air traffic controllers and flight operators plan flight schedules together based on the given capacity limit, thereby maximizing en route throughput and minimizing flight operators' costs. However, the current methods have limitations due to the lacks of consideration of the combinatorial nature of air traffic flow management decision. One of the initial attempts to overcome these limitations is the Collaborative Trajectory Options Program (CTOP), which will be initiated soon by the Federal Aviation Administration (FAA). The developed two-stage combinatorial optimization framework fits this CTOP perfectly from the flight operator's perspective. The first stage is used to find an optimal slot allocation for flights under satisfying the ration by schedule (RBS) algorithm of the FAA. To solve the formulated first stage problem efficiently, two different solution methodologies, a heuristic algorithm and a modified branch and bound algorithm, are presented. Then, flights are assigned to the resulting optimized slots in the second stage so as to minimize the flight operator's costs.