Dissertations / Theses on the topic 'Flight noise'

Thesis (M.S.) -- University of Maryland, College Park, 2008.<br>Thesis research directed by: Dept. of Aerospace Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

Thesis (Ph. D.) -- University of Maryland, College Park, 2004.<br>Thesis research directed by: Aerospace Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.

Pas de résumé<br>This work aims at developing a statistical prediction method for BroadBand Shock-Associated Noise (BBSAN), following recent work from NASA and Boeing. The approach is similar to studies performed for mixing noise models.First, a methodology has been developed to compute the mean turbulent _ow _eld using the Reynolds Averaged Navier-Stokes (RANS) equations. These equations are solved with elsA, a solver developed by ONERA. Most calculations have been performed on academic configurations. An extensive test campaign has been conducted on these configurations at Ecole Centrale de Lyon (ECL), so that calculations have been thoroughly compared to measurements. Mainly, two operating conditions have been tested. The first one is a jet at Mj = 1:15. This condition is typical of a civil engine in cruise. The second operating condition is a jet at Mj = 1:35, which rather concerns military engines.An acoustic model has been developed. It uses the RANS calculation as an input to compute Power Spectrum Densities (PSDs). The intermediate version of the model does not account for refraction effects: acoustic sources are propagated to the far-field using a free field Green's function. As will be seen, this gives good results on simple configurations.The model has been extended to account for refraction effects. This is achieved by computing a Green's function tailored to the problem. A ray tracing method coupled to an adjoint approach has been used to evaluate the Green's function. The computation of the Green's function has been validated for simple cases. The Green's function calculation has been coupled to the acoustic model. PSDs including refraction effects on dual-streamjets are presented

Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2017.<br>This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.<br>Cataloged from student-submitted PDF version of thesis.<br>Includes bibliographical references (pages 119-121).<br>The implementation of Performance Based Navigation (PBN) routes across the National Airspace System (NAS) has caused a significant concentration of flight tracks. This flight track concentration also creates a concentration of noise impacts on the communities surrounding airports, which has led to an increase in noise complaints at many airports that have implemented these routes. In order to understand these changes in noise, and to design procedures that could help mitigate any negative effects, it is important to have modeling tools capable of capturing the noise impacts of flight track variability. This thesis develops a model for this purpose. First, twenty days of radar flight trajectory data from 2015 and 2016 at Boston Logan International Airport (KBOS) is used to quantify the observed distributions of variability in speed, altitude, and lateral track position. It is shown that altitude and speed variability have relatively small impacts on noise, but that the impacts of observed lateral variability are significant. Using this information, a physics-based model is developed to capture the noise impacts of lateral flight track variability. This tool is then used to model several example scenarios. First, the changes in noise due to pre- and post-PBN procedures are examined for KBOS Runway 33L departures. Next, a hypothetical procedure is designed to intentionally introduce lateral dispersion to KBOS Runway 33L departures. Finally, the tool is used to rapidly model noise impacts on due to both arrival and departure operations on all runways at KBOS. The model is shown to reduce computational expense by 1-2 order of magnitude relative to traditional methods. The results of these example analyses show that increased lateral dispersion causes a significant noise reduction at higher noise levels directly below the flight track at the cost of wider contours at lower noise levels. Because of this, any decision to add or remove flight track lateral dispersion has highly localized impacts that depend on the geometry of the route and the population of the surrounding area, and thus must be closely analyzed on an individual basis.<br>This work was sponsored by the FAA under ASCENT Center of Excellence Project 23, Cooperative Agreement 13-C-AJFE-MIT-008.<br>by Callen T. Brooks.<br>S.M.

This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.<br>Thesis: S.M., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2019<br>"Alison Y. Yu and R. John Hansman. This report is based on the Masters Thesis of Alison Y. Yu submitted to the Department of Aeronautics and Astronautics in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology. The work presented in this report was also conducted in collaboration with: Prof R. John Hansman. Report No. ICAT-2019-07. MIT International Center for Air Transportation (ICAT) Department of Aeronautics & Astronautics Massachusetts Institute of Technology Cambridge, MA 02139 USA"--Additional title page. Cataloged from student-submitted PDF version of thesis.<br>Includes bibliographical references (pages 86-88).<br>The implementation of Performance Based Navigation (PBN), such as Area Navigation (RNAV) and Required Navigation Performance (RNP), has led to aircraft being able to fly designed flight tracks very precisely. This has led to communities citing the concentration of aircraft along one flight track as a noise issue because of the frequent overflights above specific areas. In order to assess the impact of frequent overflights, metrics for understanding the annoyance mechanism were necessary. The metric Nx, which is a count of the number of overflights above the A-weighted maximum sound level (L[subscript A,max]) of xdB during the day and (x-10)dB during the night, was investigated. The metric Nx required analysis of the L[subscript A,max] noise level to count as an overflight, as well as the number of overflights that represented the annoyance threshold. N₆₀ on a peak day with 50 overflights was shown to represent at least 80% of the complaint locations at BOS, MSP, LHR, and one runway at CLT. Alternatively peak day DNL is also shown to be a possible representative noise metric and will also be investigated. A noise metric representative of the impacts of frequent overflights allowed for communication of analysis results for possibilities for dispersed flight tracks. Important ways to communicate analysis results to stakeholders included: overall increase or decrease in population exposure to N₆₀ on a peak day with 50 overflights, the change in the number of N₆₀ overflights for the areas of impact, and presentation of the data that allowed stakeholders to understand the impact within the boundaries of their specific representative area. These tools will allow communities to understand the noise impacts of the procedures considered and will support the stakeholder decision processes.<br>"This work was sponsored by the Federal Aviation Administration (FAA) under ASCENT Center of Excellence Project 23, Cooperative Agreement 13-C-AJFE-MIT-008 and by the Massachusetts Port Authority (Massport)"--Page 5<br>by Alison Y. Yu.<br>S.M.<br>S.M. Massachusetts Institute of Technology, Department of Aeronautics and Astronautics

Today, the air transport industry has become an essential element of global society by its great contributions to the wide exchanges of cultures/people and to the rapid growth in the world economy. However, on the other hand, the adverse impacts on the environment caused by air transport, such as air pollution, noise and climate change, are drawing, increasingly, growing public concern. In order to address the steady growth in air-travel demand in the next decades through an environmentally-friendly way and realise the ACARE 2020 environmental goals, The Clean Sky programme has been launched by European Union over the period 2008 – 2013. The project research, described in this thesis and sponsored by the Clean Sky programme, aims at evaluating the feasibility of reducing the environmental impact of commercial aviation through the introduction of changes in the aircraft operational rules and procedures, as well as the application of the new-generation propfan (open rotor) engine, based on flight trajectory multidisciplinary optimisation and analysis of commercial aircraft. In order to accomplish the above research objectives, a complete methodology to achieve and realise optimum flight trajectories has been initially proposed. Then, 12 component-level models which function as simulating different disciplines, such as aircraft performance, engine performance, engine gaseous emission, and flight noise, have been developed or selected/adopted. Further, nine system-level integration and optimisation models were built. These system-level models simulate flights from Amsterdam Schiphol airport in the Netherlands to Munich airport in Germany flown by different types of aircraft through different flight phases with different optimisation objectives. Finally, detailed investigations into the flight trajectory optimisations were performed, extensive optimisation results were achieved and corresponding description, analysis and comparisons were provided. The main contributions of this work to knowledge broadly comprise the following: 1) the further development regarding the methodology of flight trajectory multidisciplinary optimisation; 2) previous work on aircraft trajectory optimisation has often considered fixed objectives over the complete flight trajectory. This research focused on representative flight phases of a flight mission with different optimisation objectives, namely, noise impact and fuel burn during the departure phase; fuel burn and flight time during en route phase; and noise impact and NOx emission during the arrival phase; 3) this research has extended the current flight trajectory optimisations to turboprop and propfan equipped aircraft. As a result, a relative complete 2D flight trajectory multidisciplinary optimisation spectrum, spanned by primary commercial aircraft types, primary flight phases and primary optimisation objectives of interest, has been built. Although encouraging progress have been achieved, this project research, as with any other research activity, is also only ‘on the way’ rather than coming to the ‘end’ point. There are still many aspects which can be improved further and there is still much new research and exploration which can be investigated further. All these have also been suggested in this thesis.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, 2018.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (pages 227-234).<br>Aircraft noise is a growing source of community concern around airports. Despite the introduction of quieter aircraft, increased precision of onboard guidance systems has resulted in new noise impacts driven by overflight frequency effects. Noise issues present a potential barrier to the continued rollout of advanced operational procedures in the US. This thesis presents a data-driven approach to simulating and communicating noise effects in the flight procedure development and modernization process, with input from multiple stakeholders with varying objectives that are technical, operational, and political in nature. First, a system-level framework is introduced for developing novel noise-reducing arrival and departure flight procedures, clarifying the role of the analyst given diverse stakeholder objectives. The framework includes relationships between baseline impact assessment, community negotiation, iterative flight procedure development, and formal implementation processes. Variability in stakeholder objectives suggests a need to incorporate noise issues in conjunction with other key operational objectives as part of larger-scale US air transportation system modernization. As part of this framework development, an airport-level noise modeling method is developed to enable rapid exposure and impact analysis for system-level evaluation of advanced operational procedures. The modeling method and framework are demonstrated by evaluating potential benefits of specific advanced procedures at 35 major airports in the US National Airspace System, including Performance Based Navigation guidance and a speed-managed departure concept.<br>by Luke L. Jensen.<br>Ph. D.

Thesis: Ph. D., Massachusetts Institute of Technology, Department of Aeronautics and Astronautics, May, 2020<br>Cataloged from the official PDF of thesis.<br>Includes bibliographical references (pages 213-223).<br>Recent changes to aircraft approach and departure procedures enabled by more precise navigation technologies have created noise concentration problems for communities beneath flight tracks. There may be opportunities to reduce community noise impacts under these concentrated flight tracks through advanced operational approach and departure procedures and advanced aircraft technologies. A modeling method to assess their impacts must consider the contributions of aircraft engine and airframe noise sources as they vary with the position, thrust, velocity, and configuration of the aircraft during the flight procedure. The objective is to develop an analysis method to design, model, and assess the community noise reduction possibilities of advanced operational flight procedures performed by conventional aircraft and advanced procedures enabled by future aircraft concepts.<br>An integrated analysis framework is developed that combines flight dynamics and noise source models to determine the community noise impacts of aircraft performing advanced operational approach and departure procedures. Aircraft noise due to the airframe and engine is modeled using an aircraft source noise module as each noise component varies throughout the flight procedure and requires internal engine performance states, the flight profile, and aircraft geometry. An aircraft performance module is used to obtain engine internal performance states and aircraft flight performance given the aircraft technology level. A force-balance-kinematics flight profile generation module converts the flight procedure definition into altitude, position, velocity, configuration, and thrust profiles given flight performance on a segment-by-segment basis.<br>The system generates single-event surface noise grids that are combined with population census data to estimate population noise exposure for a given aircraft technology level and procedure. The framework was demonstrated for both advanced approach and departure procedures and advanced aircraft technologies. The advanced procedure concepts include modified speed and thrust departures as well as continuous descent, steep, and delayed deceleration approaches for conventional aircraft. The ability to model advanced aircraft technologies was demonstrated in the evaluation of using windmilling drag by hybrid electric aircraft on approach to allow the performance of steep and delayed deceleration approaches for noise reduction beyond the performance capability of standard gas-turbine aircraft.<br>by Jacqueline Thomas.<br>Ph. D.<br>Ph.D. Massachusetts Institute of Technology, Department of Aeronautics and Astronautics

Throughout the world, birds represent the primary type of wildlife that people experience on a daily basis. However, a growing body of evidence suggests that alterations to the acoustic environment can negatively affect birds as well as humans in a variety of ways, and altered acoustics from noise pollution has the potential to influence human interactions with wild birds. In this thesis, I investigated how anthropogenic noise impacts daily behavior as well as community structure of wild birds. In the first component of this thesis, I assessed the distance at which a bird initiates flight or escape behavior (i.e., flight initiation distance or FID) in varying acoustic conditions. I surveyed 12 songbird species from three foraging guilds, ground foragers, canopy gleaners, and hawking flycatchers, and I predicted FIDs to decrease, remain the same, and increase with noise exposure, respectively. Contrary to expectations, the canopy gleaning and flycatching guilds exhibited mixed responses, with some species exhibiting unchanged FIDs with noise while others exhibited increased FIDs with noise. However, FIDs of all ground foraging species and one canopy gleaner decreased with noise levels. In the second component, I examined the feeding of wild birds, an increasingly popular recreational activity throughout North America that promotes increased sense of wellbeing by connecting people with wildlife and nature. I tested how experimental noise influences abundance, species richness, community structure and foraging behavior of songbirds at maintained bird feeders. By measuring activity levels of all species that utilized the feeders exposed to intervals of quiet and noisy conditions, I found noise to be a significant predictor of community turnover. Specifically, noise exposure resulted in increased feeder activity for two species, and decreased activity for one species. I also confirmed previous research conducted in the laboratory indicating white-crowned sparrows decrease their foraging rate under noise conditions, presumably as a trade off with visual vigilance. Considering the interactions of humans and wild birds, the results from my two thesis components indicate that the acoustic environment can play a role in how species of different foraging guilds respond to birdwatchers and what species visit bird feeders.

Among the many occupational hazards to which Army rotary-wing aviators are exposed is intense noise generated from the aircraft. The potential for permanent hearing loss and difficulty communicating in helicopter noise is well known; an appropriate way to evaluate a hearing-impaired pilotâ s safety risk due to hearing loss is not as well known. Previous research has studied communication ability in helicopter cockpit noise under different headsets, but there are not conclusive data on the combined effects of degraded speech intelligibility due to noise and flight workload under the headset technology currently available to Army helicopter pilots. In particular, there is a scarcity of information on pilots with hearing loss. Currently, Army Aeromedical standards stipulate audiometric threshold criteria for rated helicopter pilots to ensure their safe flying. If the standard is not met, a flight waiver for hearing is generally granted if the pilot demonstrates good (at least 84%) binaural word recognition ability in a quiet environment. A research study was conducted to evaluate Army helicopter pilot performance with regard to flight workload, communication signal quality, headset configuration, and pilot hearing ability. Objectives of the study included the ability to refine current Army audiometric hearing waiver criteria, and to yield data on which to base flight and headset selection recommendations for pilots. In general, it was believed that flight performance and ratings of situation awareness (SA) would decrease as flight workload increased and communication signal quality decreased, and that assistive communication devices coupled with headsets would afford improved flight performance over their passive counterpart. It was also hypothesized that normal-hearing pilots would perform better than hearing-impaired pilots would. Twenty Army helicopter pilots (one group of 10 pilots without a hearing waiver and one group of 10 pilots with a hearing waiver) participated in this study. The pilots flew three flights in a Black Hawk flight simulator, each with a different headset configuration and with varying flight workload levels and varying air traffic control (ATC) communication signal quality. Objective flight performance parameters of heading, altitude, and airspeed deviation and ATC command readbacks were measured. Additionally, measurements were taken on subjective measures of workload, SA, and headset comfort/speech intelligibility. Experimental results partially supported the research hypotheses. Results indicated that flight performance and ratings of SA were negatively affected by increased flight workload and decreased communication signal quality for both groups of pilots. Results also showed that a passive headset/passive earplug combination use by the hearing-impaired group of pilots led to degradation of certain flight performance parameters and lower ratings of SA than the headsets equipped with assistive communication technology; however, the same headset effect was not seen with the group of normal-hearing pilots. This study yielded results that support a conclusion that factors other than hearing thresholds and word recognition ability in a quiet environment should be considered when evaluating Army helicopter pilots flight safety with regard to hearing sensitivity. Rather, the synergistic effects of flight workload and communication signal quality with individual hearing levels should be considered when making continued flight recommendations and headset choice recommendations. Results also support a recommendation requiring hearing-impaired pilots to use assistive communication technology and not be permitted to fly with passive headset devices. Further research should include a functional hearing assessment in which pilot hearing requirements are determined and individual hearing abilities are compared to the requirements.<br>Ph. D.

Researchers have long known that general aviation (GA) aircraft exhibit some of the most intense and potentially damaging sound environments to a pilotâ s hearing. Yet, another potentially more ominous result of this noise-intense environment is the masking of the radio communications. Radio communications must remain intelligible, as they are imperative to the safe and efficient functioning of the airspace, especially the airspace surrounding our busiest airports, Class B and Class C. However, the high amplitude, low frequency noise dominating the GA cockpit causes an upward spreading of masking with such inference that it renders radio communications almost totally unintelligible, unless the pilot is wearing a communications headset. Even with a headset, some researchers have stated that the noise and masking effects overcome the headset performance and still threaten the pilotâ s hearing and overall safety while in the aircraft. In reaction to this situation, this experiment sought to investigate the effects which active noise reduction (ANR) headsets have on the permissible exposure levels (PELs), speech intelligibility, workload, and ultimately the pilotâ s performance inside the cockpit. Eight instrument-rated pilot participants flew through different flight tasks of varying levels and types of workload embedded in four 3.5 hour flight scenarios while wearing four different headsets. The 3.5 hours were considered long duration due the instrument conditions, severe weather conditions, difficult flight tasks, and the fatiguing effects of a high intensity noise environment. The noise intensity and spectrum in the simulator facility were specifically calibrated to mimic those of a Cessna 172. Speech intelligibility of radio communications was modified using the Speech Transmission Index (STI), while measures of flight performance and workload were collected to examine any relationships between workload, speech intelligibility, performance, and type of headset. It is believed that the low frequency attenuation advantages afforded by the ANR headset decreased the signal-to-noise ratio, thereby increasing speech intelligibility for the pilot. This increase may positively affect workload and flight performance. Estimates of subjective preference and comfort were also collected and analyzed for relevant relationships. The results of the experiment supported the above hypotheses. It was found that headsets which incorporate ANR technology do increase speech intelligibility which has a direct inverse influence on workload. For example, an increase in speech intelligibility is seen with a concomitant decrease in pilot workload across all types and levels of workload. Furthermore, flight task performance results show that the pilotâ s headset can facilitate safer flight performance. However, the factors that influence performance are more numerous and complex than those that affect speech intelligibility or workload. Factors such as the operational performance of the communications system in the headset, in addition to the ANR technology, were determined to be highly influential factors in pilot performance. This study has concluded that the pilotâ s headset has received much research and design attention as a noise attenuation device. However, it has been almost completely overlooked as a tool which could be used to facilitate the safety and performance of a general aviation flight. More research should focus on identifying and optimizing the headset components which contribute most to the results demonstrated in this experiment. The pilotâ s headset is a component of the aviation system which could economically improve the safety of the entire system.<br>Ph. D.

This thesis explores and compares traditional and reinforcement learning (RL) methods of performing 2D flight path planning in 3D space. A wide overview of natural, classic, and learning approaches to planning s done in conjunction with a review of some general recurring problems and tradeoffs that appear within planning. This general background then serves as a basis for motivating different possible solutions for this specific problem. These solutions are implemented, together with a testbed inform of a parallelizable simulation environment. This environment makes use of random world generation and physics combined with an aerodynamical model. An A* planner, a local RL planner, and a global RL planner are developed and compared against each other in terms of performance, speed, and general behavior. An autopilot model is also trained and used both to measure flight feasibility and to constrain the planners to followable paths. All planners were partially successful, with the global planner exhibiting the highest overall performance. The RL planners were also found to be more reliable in terms of both speed and followability because of their ability to leave difficult decisions to the autopilot. From this it is concluded that machine learning in general, and reinforcement learning in particular, is a promising future avenue for solving the problem of flight route planning in dangerous environments.

The aim of this essay is to study the political and aesthetical qualities in Lawrence Abu Hamdans sound piece. In Saydnaya (the missing 19db) former detainees from the infamous Syrian prison Saydnaya are interviewed about the many sounds, silences and emotions that circulated in the prison. Since they were kept in total darkness during their stay in Saydnaya, their memories and impressions are sonic. The piece can therefore be called a sonic testimony and the detainees are referred to as earwitnesses. The methodological framework of this study is outlined by Salomé Voegelin in her book Listening to Noise and Silence. In the core of this method lies the notion of deep listening (also called sonic sensibility). From listening noise and silence naturally unfold. In order to define and discover the affects of the artwork and its sonic material, the theoretical work of Gilles Deleuze, Brian Massumi and Sara Ahmed is applied. More specifically the concepts of lines of flight and affect. Emotions and sound seem to blend in the most peculiar ways. This essay is just a suggestion of how that blend might look... or should I say sound? And most importantly this essay will investigate how these non-visual forces work, stick and flow. How they can be used and what they produce. Some of the questions that this essay will touch upon are: what are the sonic affects that this artwork produces? And how does the artist use noise and silence in the construction of Saydnaya?

The purpose of this project was to evaluate noise exposures of helicopter pilots, nurses and paramedics at a hospital by collecting area and personal samples, determining noise levels inside the helmet, and evaluating the current selection of personal protective equipment (PPE). Measurements gathered during personal sampling were statistically analyzed and calculated using OSHA 1910.95 App A to determine dose, reference duration and the Time-Weighted Average (TWA). Using a mannequin head, with the noise dosimeters in the ears, tests were performed on the headset inside the helmets to determine the sound pressure levels generated from the radio communications at different volume levels. According to our results, the crew is not exposed to hearing levels above the OSHA permissible exposure limit (PEL), because their flight times are usually only 20-30 minutes and the dose not above 22% of the OSHA limit. If the total flight times were 6.5 hours or more, the crew could be above the OSHA PEL. Testing the helmet speakers resulted in a recommendation that the setting not be set above the 6 o'clock position so that the crew would not be exposed to sound pressure levels about 80 dBA

Les bruits et les polluants atmosphériques émis par les avions commerciaux représentent un défi environnemental important, un problème de santé publique et une contrainte économique pour le développement durable du transport aérien. D'un autre côté, le développement économique des régions est intimement lié au secteur du transport aérien. Ce dernier agit comme un multi-capteur économique pour supporter le développement régional et desservir les grands centres. Cette réalité s'explique entre autres par le fait que la mondialisation des marchés impose l'utilisation de moyens rapides et compétitifs pour le transport des voyageurs et des marchandises. Notre approche est une modélisation mathématique du problème de choix des trajectoires de vol dans un domaine continu. La première étape dans la modélisation d'un tel problème est l'écriture des équations qui traduisent la dynamique de vol de l'avion. Ensuite, vient la modélisation est la synthèse des critères d'optimisation. Les critères qu'on a retenus dans notre travail sont la consommation de carburant (critère d'énergie) et le bruit perçu au sol (critère de la gêne occasionnée pour les riverains). En combinant les deux parties "modèle de la dynamique du vol" et "critères d'optimisation", et en intégrant d'autres contraintes liées à la sécurité du vol, on aboutit à un modèle mathématique qui appartient à la classe des problèmes non linéaires de contrôle optimal. C'est une classe difficile de problèmes d'optimisation qui pose un certain nombre de difficultés lors de la construction d'algorithmes de résolution. Pour résoudre le problème ainsi posé, deux approches distinctes peuvent être envisagées : méthodes directes et méthodes indirectes. Nous avons implémenté une méthode dite " pseudo spectrale de Gauss " pour la résolution du problème de contrôle. Le choix de cette méthode est basé sur une propriété très importante et qui garantit l'équivalence entre l'application des deux schémas : direct et indirects. Des résultats sont présentés et discutés. Nos résultats donnent des pistes sur de nouvelles procédures de vol qui minimisent le bruit et la consommation de carburant durant les phases d'atterrissage et de décollage. Par ailleurs, la résolution numérique consolide également le potentiel des approches CDA recommandées par l'OACI. Une comparaison aux procédures standards et une analyse de sensibilité aux critères est présentée<br>Noise and air pollution from commercial aircraft represent a significant environmental challenge, a public health problem and an economic constraint to the sustainable development of air transport. On the other hand, the economical development of the regions is closely linked to the airline industry. This fact is partly explained by the the globalization of markets that requires the use of fast and competitive means to transport people and goods. We propose a mathematical model to tackle this problem by optimizing flight paths in order to minimize noise emission and fuel consumption. The first step is to express the dynamics of flight of the aircraft. Then comes the synthesis of optimization criteria. The criteria we used in our work are the fuel consumption (criterion of energy) and the perceived noise levels at the ground (criterion of inconvenience for local residents). By combining the two previous parts, and incorporating other constraints related to flight safety, we obtain a mathematical model that belongs to a class of nonlinear optimal control problems. It is a difficult class of optimization problems that raises several difficulties during the construction of solving algorithms. Two different ways can be considered to solve this problem : direct methods and indirect methods. We have developed and implemented a direct method called "Gauss Pseudo-spectral Method" to solve the optimal control problem that we obtained. The choice of this method is based on a very important property that guarantees the equivalence between the use of two schemes : direct and indirect. Results are presented and discussed. Our results provide a new view on flight procedures that minimize noise and fuel consumption during landings and takeoffs. Moreover, the numerical solution also consolidates the potential of CDA approaches which are recommended by ICAO. A comparison with standard procedures and a sensitivity analysis are presented

L'effet du vol d'avancement sur le bruit de choc de jets supersoniques sous-détendus est étudié de manière expérimentale. La structure de tels jets est d'abord explorée, avec et sans vol simulé. L'analyse employée allie des visualisations strioscopiques à des mesures quantitatives de pression statique et de vitesse, par vélocimétrie laser Doppler et vélocimétrie par images de particules. L'accent est mis sur l'étude de l'écoulement moyen et des propriétés de la turbulence dans la couche de mélange. L'effet du vol sur la composante tonale du bruit de choc, le screech, est ensuite examiné. A l'aide d'une antenne azimutale de microphones placée dans le champ proche acoustique, une analyse fine des modes du screech est notamment proposée. Par ailleurs, plusieurs effets de cette composante de bruit sur la dynamique du jet sont mis en évidence, en particulier l'oscillation des chocs ; on montre que cette oscillation est intimement liée au mode du screech. De manière à étudier spécifiquement la composante large bande du bruit de choc, diverses techniques de suppression du screech sont ensuite explorées.L'utilisation d'une tuyère crénelée s'est révélée satisfaisante pour l'éliminer de manière non-intrusive et a permis de déduire son influence sur le bruit de choc large bande. Enfin, l'effet du vol sur cette dernière composante est déterminé par l'étude de l'évolution de sa fréquence centrale, de son amplitude et de sa forme spectrale en situation de vol simulé. Une explication des tendances observées est alors proposée à la lumière des résultats aérodynamiques obtenus.

Dans un monde où l’information va de plus en plus vite, il est important de pouvoir rester connecté en permanence. De nouvelles solutions émergent pour connecter les passagers à bord d’un avion grâce aux communications par satellite. Parmi elles, on retrouve les antennes à pointage électronique dans lesquelles cette thèse de doctorat s’intègre. Une étude sur les différentes antennes existantes ou en projet est présentée. Les puces électroniques MMIC AsGa permettent d’appliquer des lois d’amplitude et de phase pour chaque élément rayonnant d’une antenne réseau. Cette thèse de doctorat porte sur la conception d’un déphaseur, après avoir étudié les technologies et les topologies de celui-ci. Ensuite, la conception d’un amplificateur faible bruit à gain variable est proposée à partir d’un état de l’art. Les résultats de simulation et de mesures de ces deux fonctions sont exposés<br>In a world where the information is moving faster and faster, it is important to be able to stay connected continuously. Some new solutions for air transport connectivity are in development thanks to the rise of satellite communications. This thesis work is part of an electronically steerable antenna array project, developed as a solution to achieve In-Flight Connectivity in Ka-band. A state- of-the art review on electronically steerable antenna arrays is also presented. In these arrays, each radiating element needs a specific amplitude and phase to obtain a scanning beam by adding their contribution. This thesis focus on the design of a GaAs MMIC chip inclusion two functions: a phase shifter and a variable-gain low-noise amplifier. The simulation and measurement results are presented for these two functions

Pour agir de manière autonome et intelligente dans un environnement, un robot mobile doit disposer de cartes. Une carte contient les informations spatiales sur l’environnement. La géométrie 3D ainsi connue par le robot est utilisée non seulement pour éviter la collision avec des obstacles, mais aussi pour se localiser et pour planifier des déplacements. Les robots de prochaine génération ont besoin de davantage de capacités que de simples cartographies et d’une localisation pour coexister avec nous. La quintessence du robot humanoïde de service devra disposer de la capacité de voir comme les humains, de reconnaître, classer, interpréter la scène et exécuter les tâches de manière quasi-anthropomorphique. Par conséquent, augmenter les caractéristiques des cartes du robot à l’aide d’attributs sémiologiques à la façon des humains, afin de préciser les types de pièces, d’objets et leur aménagement spatial, est considéré comme un plus pour la robotique d’industrie et de services à venir. Une carte sémantique enrichit une carte générale avec les informations sur les entités, les fonctionnalités ou les événements qui sont situés dans l’espace. Quelques approches ont été proposées pour résoudre le problème de la cartographie sémantique en exploitant des scanners lasers ou des capteurs de temps de vol RGB-D, mais ce sujet est encore dans sa phase naissante. Dans cette thèse, une tentative de reconstruction sémantisée d’environnement d’intérieur en utilisant une caméra temps de vol qui ne délivre que des informations de profondeur est proposée. Les caméras temps de vol ont modifié le domaine de l’imagerie tridimensionnelle discrète. Elles ont dépassé les scanners traditionnels en termes de rapidité d’acquisition des données, de simplicité fonctionnement et de prix. Ces capteurs de profondeur sont destinés à occuper plus d’importance dans les futures applications robotiques. Après un bref aperçu des approches les plus récentes pour résoudre le sujet de la cartographie sémantique, en particulier en environnement intérieur. Ensuite, la calibration de la caméra a été étudiée ainsi que la nature de ses bruits. La suppression du bruit dans les données issues du capteur est menée. L’acquisition d’une collection d’images de points 3D en environnement intérieur a été réalisée. La séquence d’images ainsi acquise a alimenté un algorithme de SLAM pour reconstruire l’environnement visité. La performance du système SLAM est évaluée à partir des poses estimées en utilisant une nouvelle métrique qui est basée sur la prise en compte du contexte. L’extraction des surfaces planes est réalisée sur la carte reconstruite à partir des nuages de points en utilisant la transformation de Hough. Une interprétation sémantique de l’environnement reconstruit est réalisée. L’annotation de la scène avec informations sémantiques se déroule sur deux niveaux : l’un effectue la détection de grandes surfaces planes et procède ensuite en les classant en tant que porte, mur ou plafond; l’autre niveau de sémantisation opère au niveau des objets et traite de la reconnaissance des objets dans une scène donnée. A partir de l’élaboration d’une signature de forme invariante à la pose et en passant par une phase d’apprentissage exploitant cette signature, une interprétation de la scène contenant des objets connus et inconnus, en présence ou non d’occultations, est obtenue. Les jeux de données ont été mis à la disposition du public de la recherche universitaire<br>Intelligent autonomous actions in an ordinary environment by a mobile robot require maps. A map holds the spatial information about the environment and gives the 3D geometry of the surrounding of the robot to not only avoid collision with complex obstacles, but also selflocalization and for task planning. However, in the future, service and personal robots will prevail and need arises for the robot to interact with the environment in addition to localize and navigate. This interaction demands the next generation robots to understand, interpret its environment and perform tasks in human-centric form. A simple map of the environment is far from being sufficient for the robots to co-exist and assist humans in the future. Human beings effortlessly make map and interact with environment, and it is trivial task for them. However, for robots these frivolous tasks are complex conundrums. Layering the semantic information on regular geometric maps is the leap that helps an ordinary mobile robot to be a more intelligent autonomous system. A semantic map augments a general map with the information about entities, i.e., objects, functionalities, or events, that are located in the space. The inclusion of semantics in the map enhances the robot’s spatial knowledge representation and improves its performance in managing complex tasks and human interaction. Many approaches have been proposed to address the semantic SLAM problem with laser scanners and RGB-D time-of-flight sensors, but it is still in its nascent phase. In this thesis, an endeavour to solve semantic SLAM using one of the time-of-flight sensors which gives only depth information is proposed. Time-of-flight cameras have dramatically changed the field of range imaging, and surpassed the traditional scanners in terms of rapid acquisition of data, simplicity and price. And it is believed that these depth sensors will be ubiquitous in future robotic applications. In this thesis, an endeavour to solve semantic SLAM using one of the time-of-flight sensors which gives only depth information is proposed. Starting with a brief motivation in the first chapter for semantic stance in normal maps, the state-of-the-art methods are discussed in the second chapter. Before using the camera for data acquisition, the noise characteristics of it has been studied meticulously, and properly calibrated. The novel noise filtering algorithm developed in the process, helps to get clean data for better scan matching and SLAM. The quality of the SLAM process is evaluated using a context-based similarity score metric, which has been specifically designed for the type of acquisition parameters and the data which have been used. Abstracting semantic layer on the reconstructed point cloud from SLAM has been done in two stages. In large-scale higher-level semantic interpretation, the prominent surfaces in the indoor environment are extracted and recognized, they include surfaces like walls, door, ceiling, clutter. However, in indoor single scene object-level semantic interpretation, a single 2.5D scene from the camera is parsed and the objects, surfaces are recognized. The object recognition is achieved using a novel shape signature based on probability distribution of 3D keypoints that are most stable and repeatable. The classification of prominent surfaces and single scene semantic interpretation is done using supervised machine learning and deep learning systems. To this end, the object dataset and SLAM data are also made publicly available for academic research

Purpose - This master thesis evaluates the hybrid-electric aircraft project E-Fan X with respect to its economical and environmental performance in comparison to its reference aircraft, the BAe 146-100. The E-Fan X is replacing one of the four jet engines of the reference aircraft by an electric motor and a fan. A turboshaft engine in the cargo compartment drives a generator to power the electric motor. --- Methodology - The evaluation of this project is based on standard aircraft design equations. Economics are based on Direct Operating Costs (DOC), which are calculated with the method of the Association of European Airlines (AEA) from 1989, inflated to 2019 values. Environmental impact is assessed based on local air quality (NOx, Ozone and Particulate Matter), climate impact (CO2, NOx, Aircraft-Induced Cloudiness known as AIC) and noise pollution estimated with fundamental acoustic equations. --- Findings - The battery on board the E-Fan X it is not necessary. In order to improve the proposed design, the battery was eliminated. Nevertheless, due to additional parts required in the new configuration, the aircraft is 902 kg heavier. The turboshaft engine saves only 59 kg of fuel. The additional mass has to be compensated by a payload reduced by 9 passengers. The DOC per seat-mile are up by more than 10% and equivalent CO2 per seat-mile are more than 16% up in the new aircraft. --- Research limitations - Results are limited in accuracy by the underlying standard aircraft design calculations. The results are also limited in accuracy by the lack of knowledge of some data of the project. --- Practical implications - The report contributes arguments to the discussion about electric flight. --- Social implications - Results show that unconditional praise given to the environmental characteristics of this industry project are not justified.

The aim of this master´s thesis is to replace the current engine M 337AK of the aeroplane Zlin 142 for the engine of Lycoming type with an appropriate propeller. Another purpose of the study is the installation of a nose undercarriage of VUT 100 type. The first part of the thesis examines the alternatives of replacement engines. Here the individual engines are compared with regard to their flight characteristics (climbing etc.). The next part presents the calculation of new CG positions, flight envelopes and the load affecting the engine mount. Finally, the last part focuses on the constructional plan for the engine installation and the structural analysis.

碩士<br>國立清華大學<br>電機工程學系<br>103<br>This thesis describes a Time of flight (ToF) technology with continuous wave modulation scheme applied in three domination (3D) CMOS imager sensors. Using integration signal equalization and sub-integration technology achieve noise cancellation and background light suppression (BLS) ability extension. A prototype 64×128 pixel imager employed these schemes experimentally achieve 67% fixed-pattern-noise (FPN), 300μV kTC noise cancelled and 30 fps in the 2D image mode. The imager implements two different pixels array compared between the image performances. The full chip system consists of their associated column parallel differential switched-capacitor OPAMP, S&H circuits, column and row decoders, enabling a pixel pitch of 10μm with nine transistors in a pixel, 24.8% fill factor in a TSMC 0.11μm CIS process, the chip size is 2.2mm×2.5mm. The innovations are contributed by this thesis, leading to the performance outlined above. First, a novel 4T in-pixel equalizer with reset noise cancellation (RNC) scheme which equal the signal after multiple integrated in two storage points. Compare to the 3T-like signal readout in conventional ToF imager which the integration points will be reset to the high voltage in the reset signal sample phase and therefore inject the thermal noise. The new technology cancels the reset noise caused by the reset MOSFET threshold variation and kTC noise. This operation improves the uniformity of imager at different exposure environments. The commonly readout circuits of the correlated double sampling (CDS) circuit can be omitted; in fact the CDS is pseudo operation in noise cancellation. Second, a sub-integration method for giving a wide dynamic range of background light suppressed ability. Third, the fully differential switched-capacitor OPAMP with sample and hold circuits are used in column-wise circuits for compensating the gain loss caused by the source follower in conventional active pixel sensors and reduced about 90% power consumption from the column shared OPAMP in the signal readout period, reaching good power efficiency.

碩士<br>崑山科技大學<br>資訊管理研究所<br>106<br>The defense report of the Republic of China in 2015 showed that the defense force of ROC needs to set up a series of guard efforts with defense policies by concentrating the defense resources on the establishment of ‘a rock-solid air defense force’ to keep the absolute safe on the Taiwan homeland. Practically, the national defense develops the combat capability of ‘innovative/asymmetric’ thru use of continuingly building new weapons and equipment, and assess the affordable scope and organization of air force to maintain a combat troop with high-quality capability. By the increasing number of aviation units, the expansion of the unit mission requirements associated with well-training flight officers. Actually, the frequent helicopter landings produce the occurrence of a number of aviation noises that causes the environmental awareness of residents in nearby residents. Recently, there are a few protestation actions for the helicopter noise problems by local residents living near the airport, such that the Army flight training department frequently changed the flight height and route for decreasing the noise. The present study uses the expert interview approach associated with statistical analysis on qualitative study for the flight members, to explore the impacts of flight training between different environmental routes and preset routes, flight instructors with situation factors in the process of flight training, to recognize the affections of noise protestation by residents which modified the training routes might affect the learning performance, and make appropriate recommendations to enhance the quality of flight training in future.

Path integral approaches have been widely used for long in both quantum mechanics as well as statistical mechanics. In addition to being a tool for obtaining the probability distributions of interest(wave functions in the case of quantum mechanics),these methods are very instructive and offer great insights into the problem. In this thesis, path integrals are extensively employed to study some very interesting problems in both equilibrium and non-equilibrium statistical mechanics. In the non-equilibrium regime, we have studied, using a path integral approach, a very interesting class of anomalous diffusion, viz. the L´evy flights. In equilibrium statistical mechanics, we have evaluated the partition function for a class of molecules referred to as the hindered rotors which have a barrier for internal rotation. Also, we have evaluated the exact quantum statistical mechanical propagator for a harmonic potential with a time-dependent force constant, valid under certain conditions. Diffusion processes have attracted a great amount of scientific attention because of their presence in a wide range of phenomena. Brownian motion is the most widely known class of diffusion which is usually driven by thermal noise. However ,there are other classes of diffusion which cannot be classified as Brownian motion and therefore, fall under the category of Anomalous diffusion. As the name suggests, the properties of this class of diffusion are very different from those for usual Brownian motion. We are interested in a particular class of anomalous diffusion referred to as L´evy flights in which the step sizes taken by the particle during the random walk are obtained from what is known as a L´evy distribution. The diverging mean square displacement is a very typical feature for L´evy flights as opposed to a finite mean square displacement with a linear dependence on time in the case of Brownian motion. L´evy distributions are characterized by an index α where 0 <α ≤ 2. When α =2, the distribution becomes a Gaussian and when α=1, it reduces to a Cauchy/Lorentzian distribution. In the overdamped limit of friction, the probability density or the propagator associated with L´evy flights can be described by a position space fractional Fokker-Planck equation(FFPE)[1–3]. Jespersen et al. [4]have solved the FFPE in the Fourier domain to obtain the propagator for free L´evy flight(absence of an external potential) and L´evy flights in linear and harmonic potentials. We use a path integral technique to study L´evy flights. L´evy distributions rarely have a compact analytical expression in the position space. However, their Fourier transformations are rather simple and are given by e−D │p│α where D determines the width of the distribution. Due to the absence of a simple analytical expression, attempts in the past to study L´evy flights using path integrals in the position space [5, 6] have not been very successful. In our approach, we have tried to make use of the elegant representation of the L´evy distribution in the Fourier space and therefore, we write the propagator in terms of a two-dimensional path integral –one over paths in the position space(x)and the other over paths in the Fourier space(p). We shall refer to this space as the ‘phase space’. Such a representation is similar to the Hamiltonian path integral of quantum mechanics which was introduced by Garrod[7]. If we try to perform the path integral over Fourier variables first, then what remains is the usual position space path integral for L´evy flights which is rather difficult to solve. Instead, we perform the position space path integral first which results in expressions which are rather simple to handle. Using this approach, we have obtained the propagators for free L´evy flight and L´evy flights in linear and harmonic potentials in the over damped limit [8]. The results obtained by this method are in complete agreement with those obtained by Jesepersen et al. [4]. In addition to these results, we were also able to obtain the exact propagator for L´evy flights in a harmonic potential with a time-dependent force constant which has not been reported in the literature. Another interesting problem that we have considered in the over damped limit is to obtain the probability distribution for the area under the trajectory of a L´evy particle. The distributions, again, were obtained for free L´evy flight and for L´evy flights subjected to linear and harmonic potentials. In the harmonic potential, we have considered situations where the force constant is time-dependent as well as time-independent. Like in the case of the over damped limit, the probability distribution for L´evy flights in the under damped limit of friction can also be described using a fractional Fokker-Planck equation, although in the full phase space. However, this has not yet been solved for any general value of α to obtain the complete propagator in terms of both position and velocity. Using our path integral approach, the exact full phase space propagators have been obtained for all values of α for free L´evy flights as well as in the presence of linear and harmonic potentials[8]. The results that we obtain are all exact when the potential is at the most harmonic. If the potential is higher than harmonic, like the cubic potential, we have used a semi classical evaluation where, we extremize the action using an optimal path and further, account for fluctuations around this optimal path. Such potentials are very useful in describing the problem of escape of a particle over a barrier. The barrier crossing problem is very extensively studied for Brownian motion (Kramers problem) and the associated rate constant has been calculated in a variety of methods, including the path integral approach. We are interested in its L´evy analogue where we consider the escape of a particle driven by a L´evy noise over a barrier. On extremizing the action which depends both on phase space variables, we arrived at optimal paths in both the position space as well as the space of the conjugate variable, p. The paths form an infinite hierarchy of instant on paths, all of which have to be accounted for in order to obtain the correct rate constant. Care has to be taken while accounting for fluctuations around the optimal path since these fluctuations should be independent of the time-translational mode of the instant on paths. We arrived at an ‘orthogonalization’ scheme to perform the same. Our procedure is valid in the limit when the barrier height is large(or when the diffusion constant is very small), which would ensure that there is small but a steady flux of particles over the barrier even at very large times. Unlike the traditional Kramers rate expression, the rate constant for barrier crossing assisted by L´evy noise does not have an exponential dependence on the barrier height. The rate constant for wide range of α, other than for those very close to α = 2, are proportional to Dμ where, µ ≈ 1 and D is the diffusion constant. These observations are consistent with the simulation results obtained by Chechkin et al. [9]. In addition, our approach when applied to Brownian motion, gives the correct dependence on D. In equilibrium statistical mechanics we have considered two problems. In the first one, we have evaluated the imaginary time propagator for a harmonic oscillator with a time-dependent force constant(ω2(t))exactly, when ω2(t) is of the form λ2(t) - λ˙(t)where λ(t) is any arbitrary function of t. We have made use of Hamiltonian path integrals for this. The second problem that we considered was the evaluation of the partition function for hindered rotors. Hindered rotors are molecules which have a barrier for internal rotation. The molecule behaves like free rotor when the barrier is very small in comparison with the thermal energy, and when the barrier is very high compared to thermal energy, it behaves like a harmonic oscillator. Many methods have been developed in order to obtain the partition function for a hindered rotor. However, most of them are some what ad-hoc since they interpolate between free-rotor and the harmonic oscillator limits. We have obtained the approximate partition function by writing it as the trace of the density matrix and performing a harmonic approximation around each point of the potential[10]. The density matrix for a harmonic potential is in turn obtained from a path integral approach[11]. The results that we obtain using this method are very close to the exact results for the problem obtained numerically. Also, we have devised a proper method to take the indistinguishability of particles into account in internal rotation which becomes very crucial while calculating the partition function at low temperatures.