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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

AN AIR TRAVEL JOURNEY

Muhammad, Halimah 01 May 2023 (has links) (PDF)
An Air Travel Journey combines the two areas of music and aviation. The composition aims to musically illustrate the different stages of a commercial flight (pre-takeoff taxiing, takeoff, cruise, landing, post-landing taxiing). In the “pre-takeoff” taxiing stage of the piece, the various pauses heard represent the constant stopping that occurs when an aircraft is taxiing on a runway. The music in this stage contains a relaxed and lyrical tone. In the transitions to “takeoff”, the tempo of the piece increases along with the volume to illustrate the increase in motion of a flight during this time. However, afterwards, in the transition to the “cruise” section, the music slows back down again to match the decrease in action that would happen on a flight when moving from takeoff to the ascent to cruise altitude. The cruise portion of the flight is the most relaxing portion. As such, the music heard in the composition has a soft and relaxing tone. Motivic ideas appear across different instruments. When transition from the “cruise” to the landing section, the tempo slows down like how an aircraft slows down when descending for landing. The tone of the piece becomes livelier during the composition. The “landing” section is the climax of the composition. The volume is loud, and a unison brass melody is heard followed by a chord spread throughout the ensemble. Finally, in the “post landing taxiing” section, the volume immediately becomes softer and contains pauses resembling the beginning of the composition. The work ends on a soft chord to illustrate the end of the flight.
42

The impact of air power on navies : the United Kingdom, 1945-1957

Benbow, Tim January 1999 (has links)
This thesis examines how air power has affected navies using the case of the United Kingdom between 1945 and 1957. Air power has given rise to numerous theories about its effect on the use of force, in which its impact on navies has been a particular theme. Many thinkers have interpreted air power as a strategic, operational and tactical challenge to navies, which would render them redundant and obsolete. Such ideas originated between the two World Wars but have continually reappeared since 1945 and were often influential in the British debate. During the period under consideration, the Royal Navy was challenged in a series of defence reviews. Although these serious and repeated attacks were generally motivated by financial considerations, they were justified primarily by claims relating to air power. It was argued that nuclear-armed air power would be sufficient to win wars, while any nuclear war would leave little role for navies. Later, this argument shifted to an emphasis on deterrence of war and it was suggested that naval forces were not vital to this deterrent. Although the Admiralty continued to justify a capability to defend sea communications as both a deterrent to war and vital in it, this case did not find favour with the government. During the mid-1950s, however, an alternative focus for the Navy emerged in the form of policing and limited wars, east of Suez. Conflicts in Korea and the Suez demonstrated that such conflicts could occur and that mobile naval forces, particularly carrier aviation, were well suited to intervention in them. It was also argued that land-based aircraft could take over some of the roles traditionally performed by naval forces, notably that of strike (against warships and shore targets) but also that of protecting shipping. These arguments were successfully defeated by the Admiralty. Land-based aircraft proved a useful complement to warships and naval aviation in protecting shipping but could only replace them in very limited areas. The Royal Navy differed from the US Navy in its conception of power projection against the land. Its capability for this task was thrown increasingly into doubt by growing Soviet submarine and air power and came to be justified by east of Suez commitments.
43

TAXATION OF UNITED STATES GENERAL AVIATION

Sobieralski, Joseph Bernard 01 May 2012 (has links)
General aviation in the United States has been an important part of the economy and American life. General aviation is defined as all flying excluding military and scheduled airline operations, and is utilized in many areas of our society. The majority of aircraft operations and airports in the United States are categorized as general aviation, and general aviation contributes more than one percent to the United States gross domestic product each year. Despite the many benefits of general aviation, the lead emissions from aviation gasoline consumption are of great concern. General aviation emits over half the lead emissions in the United States or over 630 tons in 2005. The other significant negative externality attributed to general aviation usage is aircraft accidents. General aviation accidents have caused over 8000 fatalities over the period 1994 - 2006. A recent Federal Aviation Administration proposed increase in the aviation gasoline tax from 19.4 to 70.1 cents per gallon has renewed interest in better understanding the implications of such a tax increase as well as the possible optimal rate of taxation. Few studies have examined aviation fuel elasticities and all have failed to study general aviation fuel elasticities. Chapter one fills that gap and examines the elasticity of aviation gasoline consumption in United States general aviation. Utilizing aggregate time series and dynamic panel data, the price and income elasticities of demand are estimated. The price elasticity of demand for aviation gasoline is estimated to range from -0.093 to -0.185 in the short-run and from -0.132 to -0.303 in the long-run. These results prove to be similar in magnitude to automobile gasoline elasticities and therefore tax policies could more closely mirror those of automobile tax policies. The second chapter examines the costs associated with general aviation accidents. Given the large number of general aviation operations as well as the large number of fatalities and injuries attributed to general aviation accidents in the United States, understanding the costs to society is of great importance. This chapter estimates the direct and indirect costs associated with general aviation accidents in the United States. The indirect costs are estimated via the human capital approach in addition to the willingness-to-pay approach. The average annual accident costs attributed to general aviation are found to be $2.32 billion and $3.81 billion (2006 US$) utilizing the human capital approach and willingness-to-pay approach, respectively. These values appear to be fairly robust when subjected to a sensitivity analysis. These costs highlight the large societal benefits from accident and fatality reduction. The final chapter derives a second-best optimal aviation gasoline tax developed from previous general equilibrium frameworks. This optimal tax reflects both the lead pollution and accident externalities, as well as the balance between excise taxes and labor taxes to finance government spending. The calculated optimal tax rate is $4.07 per gallon, which is over 20 times greater than the current tax rate and 5 times greater than the Federal Aviation Administration proposed tax rate. The calculated optimal tax rate is also over 3 times greater than automobile gasoline optimal tax rates calculated by previous studies. The Pigovian component is $1.36, and we observe that the accident externality is taxed more severely than the pollution externality. The largest component of the optimal tax rate is the Ramsey component. At $2.70, the Ramsey component reflects the ability of the government to raise revenue aviation gasoline which is price inelastic. The calculated optimal tax is estimated to reduce lead emissions by over 10 percent and reduce accidents by 20 percent. Although unlikely to be adopted by policy makers, the optimal tax benefits are apparent and it sheds light on the need to reduce these negative externalities via policy changes.
44

Impact of GNSS singular events on the integrity of airport navigation systems / Impact des évènements singuliers GNSS sur l'intégrité des systèmes de navigation aéroportuaires

Montloin, Leslie 10 July 2014 (has links)
Les systèmes GNSS sont actuellement utilisés en aviation civile pour estimer la position et la vitesse de l'avion pendant les phases de route jusqu'aux approches de précision. Etendre l'utilisation de GNSS aux opérations de surface en environnement aéroportuaire et sous de faibles conditions de visibilité reste un challenge pour la communauté aviation civile. En effet, durant ces opérations, les mesures GNSS peuvent être affectées par des évènements singuliers tels que les multi-trajet ou les anomalies ionosphériques. Ces évènements peuvent engendrer des erreurs de position jugées inacceptables en termes de précision et d'intégrité pour assurer le guidage de l'avion. Les algorithmes de surveillance d'intégrité GNSS actuellement utilisés ne sont pas conçus pour prendre totalement en compte les effets de tels évènements. Il est essentiel de développer des algorithmes de surveillance conçus pour protéger les utilisateurs des effets de tels évènements afin de pouvoir utiliser GNSS pour le guidage de l'avion en milieu aéroportuaire et sous de faibles conditions de visibilité. Afin de concevoir de tels algorithmes de surveillance d'intégrité, il est nécessaire de développer des modèles d'erreurs de mesures GNSS et des modèles de pannes GNSS. La thèse a été principalement orientée vers la conception de modèles d'erreurs de mesures GNSS dues aux multi-trajets et vers le développement de modèles de pannes GNSS dues aux multi-trajets. Pour ce faire, un modèle d'erreurs multi-trajets GNSS sur les mesures bi-fréquence GPSL1C+GPSL5 et GalileoE1+GalileoE5a a d'abord été proposé. Ensuite, l'impact des multi-trajets sur l'erreur de position a été étudié. Pour cette étude, un algorithme de couplage serré GPS+Galileo/IRS a été considéré. Cet algorithme est basé sur un filtre de Kalman linéarisé. Une analyse théorique et quantitative a été conduite pour étudier l'impact des erreurs de mesures GNSS dues aux multi-trajets sur le biais et sur la matrice de covariance de l'erreur de position horizontale en sortie de l'algorithme de positionnement considéré. Finalement, un modèle de pannes GNSS dues aux multi-trajets a été proposé. Ce modèle décrit la signature des pannes multi-trajets, les facteurs influençant cette signature, le modèle d'occurrence des pannes multi-trajets ainsi que les conditions d'occurrence de telles pannes / GNSSs are currently used in civil aviation to provide aircraft with position and velocity estimates from en-route to precision approach operations. Extending the use of GNSS to the guidance function during airport surface operations and under zero-visibility conditions remains a challenge. Indeed, during these operations, GNSS measurements may be affected by GNSS singular events, such as multipath or ionosphere anomalies. GNSS singular events may lead to unacceptable position errors in terms of accuracy and integrity for the zero-visibility guidance function. Current GNSS integrity monitoring systems are not designed to totally account for the GNSS singular event effects. The development of GNSS integrity monitoring systems designed to properly protect users from the singular event effects is essential to use GNSS for the guidance function under zero-visibility conditions. GNSS measurement error and integrity failure models are key inputs in the design of GNSS integrity monitoring systems. In this thesis, work has been mainly focused on the development of GNSS multipath measurement errors, on the assessment of the multipath impact on the GNSS-based position error, and on the development of GNSS multipath integrity failure models. For this matter, the dual frequency GPSL1C+GPSL5 and GalileoE1+GalileoE5a multipath pseudo- range error model adapted to airport navigation has been firstly proposed. Next, the impact of multipath on the GNSS-based position error has been assessed. To do so, a double constellation GPS+Galileo/IRS tight coupling algorithm based on a linearized Kalman filter has been selected. The theoretical and quantitative analysis of the impact of the GNSS multipath ranging errors on the horizontal position bias and on the covariance matrix of the horizontal position error have been proposed. Finally, a GNSS multipath integrity failure model has been proposed. The model describes the signature of the GNSS single multipath ranging failures, the factors influencing the signature as well as the occurrence model of these failures and their conditions of occurrence.
45

Assessing safety culture of professional pilots within selected South African based aviation organisations

Davids, Amirah Fatoma Gadija January 2016 (has links)
Magister Commercii - MCom / The aviation industry is one of many industries which is known to be a high-risk industry. Although it is a high risk industry, little research has been conducted within the industry especially with regards to safety culture. Safety culture is pivotal within the aviation industry as it reduces the potential to large scale disasters. While airlines are deemed to be highly reliable, when an accident occurs the cause usually tends to be human error. The aim of this study was to assess safety culture of professional pilots within selected South African based aviation organisations. This study utilized a safety culture quantitative survey instrument in order to collect data from pilots at selected South African based aviation organisations. The survey consisted of five themes (organisational commitment, management involvement, accountability systems, reporting systems and pilot empowerment). The pilots were required to respond to 49-item statements on a 5 point-likert scale, by only choosing one answer per statement. The results indicated that a majority of the participants had responded positively towards the items which represented a healthy safety culture within the selected South African based aviation organisations. Furthermore, a highly positive correlation exists between the themes of organisational commitment and management involvement. Multiple regression analysis showed there is an association between the five themes of safety culture with organisational commitment being a dependent variable. No significant difference was found between biographical information (such as rank, years of experience and flying hours), along with either the themes of organisational commitment or pilot empowerment.
46

Erreurs humaines en aéronautique : une étude du lien entre attention et erreurs / Human error in aviation : an investigation of the links between attention and errors

Debroise, Xavier 05 July 2010 (has links)
Dans le domaine aéronautique, comme dans de nombreux autres domaines de la vie courante ou professionnelle, les erreurs ont souvent été associées à des défaillances attentionnelles. Nos travaux s’insèrent dans cette problématique, et sont plus particulièrement focalisés sur les variations de la capacité à allouer son attention sur une tâche donnée à la suite d’une interruption. Dans un premier temps, nous avons mis en place des expérimentations qui permettent d’évaluer l’étendue des variations de performances obtenues dans une tâche à la suite d’une interruption, en fonction des composantes attentionnelles sollicitées dans la tâche à exécuter. Dans un second temps, nous avons mis en place un indicateur fiable et objectif mettant en évidence des différences dans le fonctionnement physiologique cérébral en fonction de ces composantes attentionnelles. Dans un troisième temps, nous avons été amenés à vérifier l’effet de diverses interruptions dans des situations aéronautiques réalistes. Nos travaux permettent de conclure à l’existence de fluctuations de l’attention à la suite d’une interruption, fluctuations dont la conséquence peut se traduire par des variations de performances et par différentes stratégies de gestion des erreurs et des activités. / In the aviation field, as in many other areas of personal or professional life, errors have often been associated with attentional failures. Our work is related to this issue, and is more particularly focused on variations of attention following an interruption. In a first step, we have set up experiments to measure changes in performance obtained in a task after an interruption. These variations are studied systematically according to various attentional components requested in the task at hand. In a second step, we have set up an indicator showing differences in the physiological functioning of the brain depending on these attentional components. Thirdly, we have tested the effect of various interruptions in realistic aeronautical situations. From our work, we conclude that there is a variation in attention after an interruption, the consequences of which can result in errors, performance variations, and differences in the management of errors and activities.
47

Machine Learning for Predictive Maintenance in Aviation / Apprentissage Automatique pour la Maintenance Predictive dans le Domaine de l’Aviation

Korvesis, Panagiotis 21 November 2017 (has links)
L'augmentation des données disponibles dans presque tous les domaines soulève la nécessité d'utiliser des algorithmes pour l'analyse automatisée des données. Cette nécessité est mise en évidence dans la maintenance prédictive, où l'objectif est de prédire les pannes des systèmes en observant continuellement leur état, afin de planifier les actions de maintenance à l'avance. Ces observations sont générées par des systèmes de surveillance habituellement sous la forme de séries temporelles et de journaux d'événements et couvrent la durée de vie des composants correspondants. Le principal défi de la maintenance prédictive est l'analyse de l'historique d'observation afin de développer des modèles prédictifs.Dans ce sens, l'apprentissage automatique est devenu omniprésent puisqu'il fournit les moyens d'extraire les connaissances d'une grande variété de sources de données avec une intervention humaine minimale. L'objectif de cette thèse est d'étudier et de résoudre les problèmes dans l'aviation liés à la prévision des pannes de composants à bord. La quantité de données liées à l'exploitation des avions est énorme et, par conséquent, l'évolutivité est une condition essentielle dans chaque approche proposée.Cette thèse est divisée en trois parties qui correspondent aux différentes sources de données que nous avons rencontrées au cours de notre travail. Dans la première partie, nous avons ciblé le problème de la prédiction des pannes des systèmes, compte tenu de l'historique des Post Flight Reports. Nous avons proposé une approche statistique basée sur la régression précédée d'une formulation méticuleuse et d'un prétraitement / transformation de données. Notre méthode estime le risque d'échec avec une solution évolutive, déployée dans un environnement de cluster en apprentissage et en déploiement. À notre connaissance, il n'y a pas de méthode disponible pour résoudre ce problème jusqu'au moment où cette thèse a été écrite.La deuxième partie consiste à analyser les données du livre de bord, qui consistent en un texte décrivant les problèmes d'avions et les actions de maintenance correspondantes. Le livre de bord contient des informations qui ne sont pas présentes dans les Post Flight Reports bien qu'elles soient essentielles dans plusieurs applications, comme la prédiction de l'échec. Cependant, le journal de bord contient du texte écrit par des humains, il contient beaucoup de bruit qui doit être supprimé afin d'extraire les informations utiles. Nous avons abordé ce problème en proposant une approche basée sur des représentations vectorielles de mots. Notre approche exploite des similitudes sémantiques, apprises par des neural networks qui ont généré les représentations vectorielles, afin d'identifier et de corriger les fautes d'orthographe et les abréviations. Enfin, des mots-clés importants sont extraits à l'aide du Part of Speech Tagging.Dans la troisième partie, nous avons abordé le problème de l'évaluation de l'état des composants à bord en utilisant les mesures des capteurs. Dans les cas considérés, l'état du composant est évalué par l'ampleur de la fluctuation du capteur et une tendance à l'augmentation monotone. Dans notre approche, nous avons formulé un problème de décomposition des séries temporelles afin de séparer les fluctuations de la tendance en résolvant un problème convexe. Pour quantifier l'état du composant, nous calculons à l'aide de Gaussian Mixture Models une fonction de risque qui mesure l'écart du capteur par rapport à son comportement normal. / The increase of available data in almost every domain raises the necessity of employing algorithms for automated data analysis. This necessity is highlighted in predictive maintenance, where the ultimate objective is to predict failures of hardware components by continuously observing their status, in order to plan maintenance actions well in advance. These observations are generated by monitoring systems usually in the form of time series and event logs and cover the lifespan of the corresponding components. Analyzing this history of observation in order to develop predictive models is the main challenge of data driven predictive maintenance.Towards this direction, Machine Learning has become ubiquitous since it provides the means of extracting knowledge from a variety of data sources with the minimum human intervention. The goal of this dissertation is to study and address challenging problems in aviation related to predicting failures of components on-board. The amount of data related to the operation of aircraft is enormous and therefore, scalability is a key requirement in every proposed approach.This dissertation is divided in three main parts that correspond to the different data sources that we encountered during our work. In the first part, we targeted the problem of predicting system failures, given the history of Post Flight Reports. We proposed a regression-based approach preceded by a meticulous formulation and data pre-processing/transformation. Our method approximates the risk of failure with a scalable solution, deployed in a cluster environment both in training and testing. To our knowledge, there is no available method for tackling this problem until the time this thesis was written.The second part consists analyzing logbook data, which consist of text describing aircraft issues and the corresponding maintenance actions and it is written by maintenance engineers. The logbook contains information that is not reflected in the post-flight reports and it is very essential in several applications, including failure prediction. However, since the logbook contains text written by humans, it contains a lot of noise that needs to be removed in order to extract useful information. We tackled this problem by proposing an approach based on vector representations of words (or word embeddings). Our approach exploits semantic similarities of words, learned by neural networks that generated the vector representations, in order to identify and correct spelling mistakes and abbreviations. Finally, important keywords are extracted using Part of Speech Tagging.In the third part, we tackled the problem of assessing the health of components on-board using sensor measurements. In the cases under consideration, the condition of the component is assessed by the magnitude of the sensor's fluctuation and a monotonically increasing trend. In our approach, we formulated a time series decomposition problem in order to separate the fluctuation from the trend by solving a convex program. To quantify the condition of the component, we compute a risk function which measures the sensor's deviation from it's normal behavior, which is learned using Gaussian Mixture Models.
48

THE NATIONAL AIR RACES AND THE MATURATION OF THE AVIATION INDUSTRY (1929-1939)

Harten, Ian Kenneth January 2011 (has links)
No description available.
49

Some empirical results for the airline and air transport markets of a small developing country

Melville, Juliet A. January 1995 (has links)
No description available.
50

The Agile Rapid Global Combat Support (ARGCS) system a cost and benefit analysis of including the ARGCS technologies in the acquisition of the Enhanced Consolidated Support System (ECASS)

Lund, John N. 12 1900 (has links)
The purpose of this project is to provide a final business case analysis of the technologies demonstrated in the Agile Rapid Global Combat Support (ARGCS) system. Three theses and one professional paper have previously analyzed the ARGCS Advanced Concept Technology Demonstration (ACTD) return on (proposed) investment. This project will review those works, provide a history of the ARGCS ACTD, discuss the goals for the ACTD and compare alternatives. In particular, this analysis builds on previous efforts, including the Discrete-Event Simulation Model developed in the Bello, Rios, Carpenter thesis (December 2006). The ultimate goal of this project is to assist in the analysis of the ARGCS technologies and what benefit they would provide if included in the proposed next generation of Naval Aviation test equipment, currently called the Enhanced Consolidated Automated Support System (ECASS). / US Navy (USN) author.

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