Dissertations / Theses on the topic 'Flight recovery'

Safety in air transport has always been of paramount importance. The very nature of aircraft navigating through the atmosphere brings with it associated risks and dangers. Some of these dangers are manifested in the form of adverse atmospheric disturbances. Two common examples of these atmospheric disturbances are the microburst and the wake vortex. This thesis explores the response and recovery performance of a General Aviation-based Model Reference Adaptive Control (MRAC) control system when subjected to these atmospheric disturbances. For the microburst condition, an existing 3DOF MRAC controller developed through prior research is integrated with nonlinear aerodynamics and an envelope protection scheme that augments the flight envelope of a Beechcraft Bonanza/CJ-144 as it encounters conditions pursuant to a microburst condition. Through simulation, the envelope protection scheme is shown to improve the chances of safe recovery in the event of a microburst encounter, by limiting the amount of total kinetic energy loss as the aircraft enters the microburst. For the wake vortex condition, an existing 6DOF MRAC controller is used as a baseline, to which a custom-developed 3D wake vortex model is added. Nonlinear components are incorporated into the existing linear aerodynamics, along with an envelope protection scheme. Pilot-in-the-loop simulated flight testing is conducted to evaluate recovery performance under three control modes: controller only, controller with pilot, and pilot only without controller. The control modes with the controller active are shown to yield much better recovery performance in the event of a wake vortex encounter. Additional efforts include the complete development of a MATLAB/Simulink-based 6DOF Aircraft Motion Visualizer and an X-Plane-based external simulation interface, both used as tools to aid in analysis of results and simulated flight testing.
Thesis (M.S.)--Wichita State University, College of Engineering, Dept. of Aerospace Engineering

Le travail effectué au cours de cette thèse tente d’apporter des solutions algorithmiques à la problématique de reprise au décrochage d’un aéronef. A travers de nombreux exemples d’application sur des modèles aérodynamiques, le lecteur pourra appréhender les concepts abstraits présentés dans cette thèse. Alors que la capacité pour un aéronef à revenir à une situation nominale après une sortie du domaine de vol est un élément clé pour les systèmes de transport aérien du futur, les recherches menées dans ce cadre sont encore peu nombreuses. Pourtant,un tel dépassement conduit généralement à une perte de contrôle (dénommée LOC-I), que l’Association du Transport Aérien International (IATA) a classé dans la catégorie des « risques les plus élevés pour l’aviation ». Dans un premier temps, nous avons montré que les modèles polynomiaux habituellement utilisés en théorie des systèmes ne représentent pas fidèlement l’aérodynamique d’un modèle d’avion sur l’ensemble de son enveloppe de vol. Nous avons donc tout d’abord montré qu’un modèle polynomial par morceaux représente avec exactitude les coefficients aérodynamiques pour les angles d’attaque faibles et élevés. Nous avons alors pu étendre à cette classe de systèmes, récentes d’étude de bifurcation et d’analyse de stabilité qui utilisent des techniques de programmation semi-définie basées sur la positivité de polynômes (SOS); nous avons notamment appliqué ces résultats au modèle d’avion de transport générique dénommé GTM. Dans le même esprit, nous avons développé un modèle pour un petit aéronef à voilure fixe basé sur des simulations numériques en mécanique des fluides (CFD). Les coefficients dynamiques n’étant pas déterminés en CFD, nous avons identifié le coefficient d’amortissement du tangage en comparant l’analyse de bifurcation et les données de vol, ce qui nous a permis d’étudier à la fois la dynamique et la stabilité du vol en cas de fort décrochage.Des résultats antérieurs ont montré que les techniques SOS étaient prometteuses pour la certification des lois de commande pour des systèmes non-linéaires, cependant sans avoir été appliqués à l’ingénierie aéronautique. En adaptant ces techniques aux modèles polynomiaux par morceaux,nous avons montré qu’il est désormais possible de les utiliser d’une manière précise mais réalisable sur le plan calculatoire. Ensuite, nous avons synthétisé des lois de commandes linéaires et polynomiales pour la récupération d’un fort décrochage. En outre, nous sommes désormais en mesure d’estimer des régions d’attraction pour des modèles polynomiaux par morceaux; pour cela, nous avons proposé un algorithme amélioré pour l’analyse de stabilité locale des systèmes à commutation, tels que ceux qui sont définis par des splines, rendant ainsi notre travail disponible pour l’analyse et la certification futures de modèles d’avion très fidèles.La commande prédictive basée modèle (MPC) s’est avérée être une approche très efficace lorsque la dynamique du système est fortement non linéaire et soumise à des contraintes d’état qui rendent difficile la récupération après le décrochage. Cependant, pour des systèmes réalistes,il est nécessaire de prendre des précautions afin de prouver rigoureusement la stabilité en boucle fermée. En utilisant la technique SOS, nous avons ainsi montré la stabilité d’une stratégie de récupération d’un fort décrochage visant à minimiser la perte d’altitude. Nous avons aussi montré qu’une telle stratégie de commande permet la récupération d’une spirale infernale en utilisant le simulateur GTM.Les résultats de cette thèse sont donc prometteurs et fournissent de nouvelles approches théoriques pour la modélisation, l’analyse de stabilité et le contrôle de la dynamique des futurs aéronefs ainsi que pour le développement et la certification de systèmes de commande de vol visant a prévenir les accidents dus à la perte de contrôle
Upset flight dynamics are characterised by unstable, highly nonlinear behaviourof the aircraft aerodynamic system. As upsets often lead to in-flight loss-of-control (LOC-I) accidents,it still poses a severe threat to today’s commercial aviation. Contributing to almost everysecond fatality in civil aviation while representing merely 10% of the total accidents (both fataland nonfatal), the International Air Transport Association has classified LOC-I as the “highestrisk to aviation safety”. Considerable effort has been undertaken in response by academics,manufacturers, commercial airlines, and authorities to predict and prevent LOC-I events as wellas recover from upset conditions into the nominal flight envelope. As result, researchers fromboth aeronautical engineering and system theory have made significant contributions towardsaviation safety; however, approaches from engineering and theory are rather disparate. This thesistherefore focuses on the application and transfer of system theoretical results to engineeringapplications.In particular, we have found simple polynomial models for aircraft dynamics, despite commonin the system theoretical literature, failing to represent full-envelope aerodynamics accurately.Advanced fitting methods such as multi-variate splines, on the other hand, are unsuitable forsome of the proposed functional analysis methods. Instead, a simple piecewise defined polynomialmodel proves to be accurate in fitting the aerodynamic coefficients for low and high angles ofattack. State-of-the-art bifurcation analysis and analysis based on sum-of-squares programmingtechniques are extended for this class of models and applied to a piecewise equations of motionof the Generic Transport Model (GTM). In the same spirit, we develop a model for a small,fixed-wing aircraft based on static continuous fluid dynamics (CFD) simulations. In the lackof dynamic coefficients from CFD, we identify a pitch-damping model comparing bifurcationanalysis and flight data that predicts well dynamics and stability of deep-stall flight.Previous developments in sum-of-squares programming have been promising for the certificationof nonlinear dynamics and flight control laws, yet their application in aeronauticalengineering halted. In combination with piecewise polynomial modeling, we are able to re-applythis technique for analysis in an accurate but computationally feasible manner to verify stablerecovery. Subsequently, we synthesise inherently stable linear and polynomial feedback laws fordeep-stall recovery. We further extend the estimation of regions of attraction for the piecewisepolynomial model towards an improved algorithm for local stability analysis of arbitrary switchingsystems, such as splines, thus making our work available for future analysis and certificationof highly accurate algebraic models.With highly nonlinear dynamics and critical state and input constraints challenging upsetrecovery, model-predictive control (MPC) with receding horizon is a powerful approach. MPCfurther provides a mature stability theory contributing towards the needs for flight control certification.Yet, for realistic control systems careful algebraic or semi-algebraic considerationsare necessary in order to rigorously prove closed-loop stability. Employing sum-of-squares programming,we provide a stability proof for a deep-stall recovery strategy minimising the loss ofaltitude during recovery. We further demonstrate MPC schemes for recovery from spiral andoscillatory spin upsets in an uncertain environment making use of the well-known and freelyavailable high-fidelity GTM desktop simulation.The results of this thesis are thus promising for future system theoretic approaches in modeling,analysis, and control of aircraft upset dynamics for the development and certification offlight control systems in order to prevent in-flight loss-of-control accidents

The aurora phenomena is a remarkable sight, commonlyrefereed to as polar or northern lights. A previous spaceexperiment SPIDER was dedicated to measure electric fieldsand characterize plasma properties in the aurora, using tenFree Falling Units (FFU) ejected from a sounding rocket. Theexperiment was successful but some problems arose. A newexperiment WOLF is committed to solve those problems andre-doing the experiment.This paper describes the process of developing a new recoveryand flight data recording system for the WOLF experiment, usingheritage from the previous SPIDER experiment. The developedsystem will be used on the upcoming WOLF experiment rocketlaunch in February 2018.The thesis analyzed hardware problems in previous design toimprove robustness and reliability, identified obsolete componentsfor replacement and added functionality for the new system. Anew hardware system was developed with schematics and PCBlayout ready for manufacturing. Also, plans for the firmware wasestablished. In the paper it is discussed about topics that shouldbe considered in the future work in developing the system andhow the system can be re-purposed for similar experiment in thefuture.

In recent years European airspace has become increasingly congested and airlines can now observe that en-route capacity constraints are the fastest growing source of flight delays. In 2010 this source of delay accounted for 19% of all flight delays in Europe and has been increasing with an average yearly rate of 17% from 2005 to 2010. This paper suggests and evaluates an approach to how disruption management can be combined with flight planning in order to create more proactive handling of the kind of disruptions, which are caused by congested airspace. The approach is evaluated using data from a medium size European carrier and estimates a lower bound saving of several million USD.

Abstract In this thesis, a new type of laser diode transmitter using enhanced gain-switching suitable for use with a single photon avalanche diode (SPAD) detector was developed and tested in the pulsed time-of-flight laser range finding (lidar) application. Several laser diode versions were tested and the driving electronics were developed. The driving electronics improvements enabled a pulsing frequency of up to 1 MHz, while the maximum laser output power was about 5–40 W depending on the laser diode dimensions. The large output power is advantageous especially in conditions of strong photon noise emerging from ambient light outdoors. The length of the laser pulse matches the jitter of a typical SPAD detector providing several advantages. The new laser pulser structure enables a compact rangefinder for 50 m distance measurement outdoors in sunny conditions with sub-centimeter precision (σ-value) at a valid distance measurement rate of more than 10 kHz, for example. Single photon range finding techniques were also shown to enable a char bed level measurement of a recovery boiler containing highly attenuating and dispersing flue gas. In addition, gated single photon detector techniques were shown to provide a rejection of fluorescent photons in a Raman spectroscope leading to a greatly improved signal-to-noise ratio. Photonic effects were also studied in the case of a pulsed time-of-flight laser rangefinder utilizing a linear photodetector. It was shown that signal photon noise has an effect on the optimum detector configuration, and that pulse detection jitter can be minimized with an appropriate timing discriminator
Tiivistelmä Tässä työssä kehitettiin uudentyyppinen, tehostettua "gain-switchingiä" hyödyntävä laserdiodilähetin käytettäväksi yksittäisten fotonien avalanche-ilmaisimien (SPAD) kanssa, ja sitä testattiin pulssin lentoaikaan perustuvassa laseretäisyysmittaussovelluksessa. Useita laserdiodiversioita testattiin ja ohjauselektroniikkaa kehitettiin. Ohjauselektroniikan parannukset mahdollistivat jopa 1 MHz pulssitustaajuuden, kun taas laserin maksimiteho oli noin 5–40 W riippuen laserdiodin dimensioista. Suuri lähtöteho on edullinen varsinkin vahvoissa taustafotoniolosuhteissa ulkona. Laserpulssin pituus vastaa tyypillisen SPAD-ilmaisimen jitteriä tarjoten useita etuja. Uusi laserpulssitinrakenne mahdollistaa esimerkiksi kompaktin etäisyysmittarin 50 m mittausetäisyydelle ulkona aurinkoisessa olosuhteessa mm–cm -mittaustarkkuudella (σ-arvo) yli 10 kHz mittaustahdilla. Yksittäisten fotonien lentoaikamittaustekniikan osoitettiin myös mahdollistavan soodakattilan keon korkeuden mittauksen, jossa on voimakkaasti vaimentavaa ja dispersoivaa savukaasua. Lisäksi portitetun yksittäisten fotonien ilmaisutekniikan osoitettiin hylkäävän fluoresenssin synnyttämiä fotoneita Raman-spektroskoopissa, joka johtaa selvästi parempaan signaali-kohinasuhteeseen. Fotoni-ilmiöitä tutkittiin myös lineaarista valoilmaisinta hyödyntävän pulssin kulkuaikamittaukseen perustuvan lasertutkan tapauksessa. Osoitettiin, että signaalin fotonikohina vaikuttaa optimaaliseen ilmaisinkonfiguraatioon, ja että pulssin ilmaisujitteri voidaan minimoida sopivalla ajoitusdiskriminaattorilla

Dissertação de Mestrado em Psicologia Social e das Organizações apresentada ao ISPA - Instituto Universitário
O presente estudo pretende fornecer evidências empíricas das potenciais consequências da organização dos horários de trabalho, das caraterísticas do trabalho e das experiências de recuperação nos níveis de fadiga percepcionados no início e no final do PSV. A literatura evidencia como indicadores da fadiga ocupacional: a distinção entre voos de NB e WB, o planeamento da escala de trabalho, a “dívida” de sono e a duração do período de tempo em que se está acordado. Um total de 51 tripulantes de cabine participaram neste estudo, transversalmente em 82 PSV categorizados em NB e WB. Para avaliar a fadiga ocupacional utilizou-se o CIS (Bultmann et al., 2000; D’Oliveira, 2012), a Fadiga Samn-Perelli (Samn & Perelli, 1982) e a Sonolência Karolinska (Åkerstedt & Gillbert, 1990). Para medir as experiências de recuperação a The Recovery Experience (Sonnentag & Fritz, 2007; D’Oliveira, 2012). Os resultados explanam o efeito e associação das variáveis inerentes ao contexto de trabalho nas medidas de fadiga ocupacional. Verificou-se que o modelo de investigação proposto, identifica a disrupção do ritmo circadiano (causada por despertares cedo e voos noturnos), o período de tempo acordado (vigília) e as experiências de recuperação como principais indicadores de fadiga ocupacional nos dois momentos de mensuração. Não existiu uma diferenciação estatisticamente significativa entre os voos categorizados, NB e WB. Verificou-se que o distanciamento psicológico é preditor da Fadiga Samn-Perelli no momento inicial; e que a Fadiga Samn-Perelli reportada no momento final tem como preditores a duração do PSV e a Fadiga Samn-Perelli no momento inicial.
ABSTRACT: This study aims to provide empirical evidences regarding the potential consequences of non-standard work schedules, job characteristics and recovery experiences in the perceived fatigue levels at the beginning and end of PSV. The literature suggests the distinction between NB and WB flights, the rostering, sleep debt and wakefulness as occupational fatigue indicators. A total of 51 flight attendants participated in this study across 82 PSV categorized in NB and WB. To assess the occupational fatigue it was used CIS (Bultmann et al., 2000; D’Oliveira, 2012), Fatigue Samn-Perelli (Samn & Perelli, 1982) and Karolinska Sleepiness Scale (Åkerstedt & Gillbert, 1990). To measure recovery experiences it was used The Recovery Experience Scale (Sonnentag & Fritz, 2007; D’Oliveira, 2012). The findings show the effect and association of variables inherent to the working context in measuring occupational fatigue. It has been found that the proposed research model identifies the circadian disruption (caused by early-birds and late calls), the extended wakefulness and recovery experiences, as key indicators of occupational fatigue in both measurement moments. There was not a significant statistical difference between flights, NB and WB. It was found that psychological detachment is a predictor of subjective fatigue Samn-Perelli in the initial moment. Both, subjective fatigue Samn-Perelli (initial moment) and time length of the PSV are predictors of fatigue levels (Samn-Perelli) in the final moment.

This paper addresses the issue of security and integration of UAVs in air traffic operations and analyses possible risks. This work defines methodology to demonstrate airworthiness of the parachute recovery system under extreme climatic conditions. The first part of the methodology deals with the compliance performance requirements in external environment and the second part verifies performance parachute canopy. Methodology developed herein is subsequently verified by practical tests on parachute recovery system Galaxy GBS 10.

This dissertation develops the visual pursuit method for air-to-air tracking and rendezvous of unmanned aircraft systems. It also shows the development of vector-field and proportional-integral methods for controlling UAS flight in formation with other aircraft. The visual pursuit method is a nonlinear guidance method that uses vision-based line of sight angles as inputs to the algorithm that produces pitch rate, bank angle and airspeed commands for the autopilot to use in aircraft control. The method is shown to be convergent about the center of the camera image frame and to be stable in the sense of Lyapunov. In the lateral direction, the guidance method is optimized to balance the pursuit heading with respect to the prevailing wind and the location of the target on the image plane to improve tracking performance in high winds and reduce bank angle effort. In both simulation and flight experimentation, visual pursuit is shown to be effective in providing flight guidance in strong winds. Visual pursuit is also shown to be effective in guiding the seeker while performing aerial docking with a towed aerial drogue. Flight trials demonstrated the ability to guide to within a few meters of the drogue. Further research developed a method to improve docking performance by artificially increasing the length of the line of sight vector at close range to the target to prevent flight control saturation. This improvement to visual pursuit was shown to be an effective method for providing guidance during aerial docking simulations. An analysis of the visual pursuit method is provided using the method of adjoints to evaluate the effects of airspeed, closing velocity, system time constant, sensor delay and target motion on docking performance. A method for predicting docking accuracy is developed and shown to be useful for predicting docking performance for small and large unmanned aircraft systems.

Le projet de thèse consiste à développer une solution pour l'atterrissage d'un drone à voilure fixe de configuration classique dans une zone limitée. Le principal défi consiste à réduire la vitesse de l'avion à une phase minimale pendant le vol, à l'aide d'algorithmes de contrôle automatique. La réduction de la vitesse d'un drone à voilure fixe s'effectue en augmentant son angle d'attaque, ce qui implique un freinage par la force de traînée. Cependant, cette manœuvre est critique pour un avion conventionnel, parce que si son angle d'attaque augmente au-delà de l'angle de décrochage, le véhicule peut perdre sa contrôlabilité, c'est-à-dire qu'il est possible que le véhicule aérien s'effondre et que sa structure soit endommagée. Le modèle mathématique est une représentation d'équations qui décrit le comportement de la dynamique du système. En considérant plusieurs variables pour obtenir une meilleure approximation de la dynamique du système, dans notre cas le véhicule à voilure fixe, la conception des stratégies de contrôle sera plus difficile et plus complexe. Dans ce travail de recherche, nous utiliserons un modèle mathématique non linéaire car les effets de décrochage peuvent être inclus par des approximations mathématiques du moment de tangage, des forces de portance et de traînée. Cela nous permet d'obtenir une meilleure performance des lois de contrôle pour la navigation autonome du drone à voilure fixe. L'une des limites des véhicules à voilure fixe est qu'ils atterrissent dans des espaces de dimensions réduites et que le pourcentage de dommages subis par leur structure est élevé. En outre, les perturbations extérieures et l'inexpérience des pilotes augmentent le risque de dommages. Il est bien connu qu'il est très difficile de satisfaire aux conditions d'une piste d'atterrissage. Par conséquent, la communauté scientifique s'est efforcée de mettre au point des solutions pour l'atterrissage dans des zones limitées. Dans la littérature, on trouve quelques solutions basées sur des véhicules hybrides et des systèmes de récupération. Les véhicules hybrides consistent à modifier la structure d'un véhicule à voilure fixe. Les moteurs sont répartis stratégiquement pour obtenir une configuration de véhicule multirotor, offrant certaines caractéristiques telles que le décollage et l'atterrissage verticaux. Cependant, ces actionneurs augmentent la masse du véhicule, la consommation d'énergie (ce qui réduit la durabilité du vol), la probabilité de défaillance, le coût d'acquisition, de réparation et d'entretien. Notre objectif dans ce travail de recherche est de concevoir et de valider des stratégies de contrôle pour l'atterrissage d'un drone à voilure fixe dans un espace limité. Les stratégies de contrôle ont été conçues selon deux approches : la première est basée sur le développement de manœuvres pour un drone à voilure fixe afin de réduire la vitesse à une phase minimale pendant le vol. Dans la deuxième approche, nous avons travaillé sur les stratégies de contrôle pour l'atterrissage d'un drone à voilure fixe sur un véhicule terrestre en mouvement. Une stratégie de contrôle a été proposée pour réduire la vitesse du drone à voilure fixe au minimum afin d'être capturé par un système de récupération. La stratégie de contrôle a été divisée en trois étapes de vol : dans la première étape, l'avion s'aligne dans le plan x-y tandis qu'il est conduit à une altitude souhaitée pour effectuer un vol de croisière. L'étape suivante consiste en un vol ascendant, axé sur le suivi d'une référence angulaire basée sur une trajectoire phugoïde. Cette trajectoire implique une augmentation de l'angle d'attaque jusqu'à l'angle de décrochage de l'avion. Ainsi, la vitesse aérienne obtient une réduction maximale dans des conditions sûres, permettant au drone d'être capturé par le système de récupération. Toutefois, si le drone n'est pas capturé par le système de récupération, une stratégie de contrôle est appliquée pour rétablir le vol de l'aéronef
The development of this thesis consists of designing some control strategies that allow a fixedwing drone with classical configuration to perform a safe landing in a limited area. The main challenge is to reduce the aircraft’s airspeed avoiding stall conditions. The developed control strategies are focused on two approaches: the first approach consists of the designing airspeed reduction maneuvers for a fixed-wing vehicle to be captured by a recovery system and for a safe landing at a desired coordinate. The next approach is focused on landing a fixed-wing drone on a moving ground vehicle. A dynamic landing trajectory was designed to lead a fixedwing vehicle to the position of a ground vehicle, reaching its position in a defined distance. Moreover, this trajectory was used in a cooperative control design. The control strategy consists of the synchronization of both vehicles to reach the same position at a desired distance. The aerial vehicle tracks the dynamic landing trajectory, and the ground vehicle controls its speed. In addition, we will propose a control architecture with a different focus, where the ground vehicle performs the tracking task of the aerial vehicle’s position in order to be captured. And, the drone’s task is to track a descending flight until the top of the ground vehicle. However, considering the speed difference between both vehicles. Therefore, we propose a new control architecture defining that the aircraft performs an airspeed reduction strategy before beginning its landing stage. The aircraft will navigate to a minimum airspeed, thus, allowing the ground vehicle to reach the fixed-wing drone’s position by increasing its speed. The control laws of each strategy were determined by developing the Lyapunov stability analysis, thus, the stability is guaranteed in each flight stage. Finally, the control strategies were implemented on prototypes allowing us to validate their performance and obtain satisfactory results for safe landing of a fixed-wing drone with classical configuration

Thesis (Ph. D.)--Ohio State University, 2004.
Title from first page of PDF file. Document formatted into pages; contains x, 126 p.; also includes graphics. Includes bibliographical references (p. 116-121).

This thesis deals with high angle of attack behaviour of a generic delta wing model aircraft. A high angle of attack wind tunnel database has been generated for this aircraft and based upon the bifurcation analysis of the data and the results of extensive simulations, it has been shown in the thesis that the post stall behaviour of this aircraft is both unstable and unpredictable. Unpredictability of aircraft behaviour arises from the fact that the aircraft response is oscillatory and divergent; the aircraft state trajectories do not settle down to any stable limit set and very often exceed valid aerodynamic database limits. This unpredictability of behaviour raises a major difficulty in the design of a procedure to recover the aircraft to normal flight regime in case the aircraft stalls and departs accidentally. A new methodology has been presented in this thesis to recover such unstable aircraft. In this methodology, a nonlinear controller is first designed at high angles of attack. This controller is connected by the pilot after the departure of the aircraft and the controller drives the aircraft to a well-defined spin condition. Thus, the controller makes the post stall aircraft behaviour predictable. Then a set of automatic recovery inputs is designed to reduce aircraft rotations and to lower the angle of attack. The present aircraft model is unstable at low angle of attack flight conditions as well and therefore to stabilize the aircraft to a low angle of attack level flight, another controller is designed. The high angle of attack controller is disconnected and the low angle of attack controller is connected automatically during the recovery process. The entire methodology is tested using extensive non-linear six degree-of-freedom simulations and the efficacy of the technique is established. The nonlinear controller that stabilizes the aircraft to a spin condition is designed using feedback linearization. The stability of a closed loop system obtained using feedback linearization is determined by the stability of the zero dynamics of the open loop plant. It has been shown in literature that the eigenvalues of the linearized zero dynamics are the same as the transmission zeros of the linearized plant at the equilibrium point. It is also well known that the location of transmission zeros of a linear system can be changed by the choice of outputs. In this thesis it is shown that if it is possible to reassign the outputs, then the feedback linearization based design for a linear system becomes very similar to a controller design for eigenvalue assignment. This thesis presents a new two-step procedure to obtain a locally stable and optimally robust closed loop system using feedback linearization. In the first step of this procedure optimal locations of the transmission zeros are found and in the second step, optimal outputs are constructed to place the system transmission zeros at these locations. The same outputs can then be used to construct nonlinear feedback for the nonlinear system and the resultant closed loop system is guaranteed to be locally robustly stable. The high angle of attack controller is designed using this procedure and its performance is presented in the thesis. The stabilized spin equilibrium point of the closed loop system is also shown to have a large domain of attraction. Having designed a locally robust stabilizing controller, the thesis addresses the problem of the evaluation of robustness of the stability of the equilibrium point in a nonlinear framework. The thesis presents a general method to construct bounds on the additive perturbations of the system vector field over a large region in the domain of attraction of a stable equilibrium point using Lyapunov functions. If the system perturbations lie within these bounds, the system is guaranteed to be stable. The thesis first proposes a method to numerically construct a Lyapunov function over a large region in the domain of attraction. In this method a sequence of Lyapunov functions are constructed such that each function in the sequence gives a larger estimate of the domain of attraction than the previous one. The seminal idea for this method is obtained from the existing literature and this idea is considerably generalized. Using this method, it is possible to numerically obtain a Lyapunov function value at each point in the domain of attraction, but the Lyapunov function does not have an analytical form. Hence, it is proposed to represent this function using neural networks. The thesis then discusses a new method to construct perturbation bounds. It is shown that the perturbation bounds obtained over a large region in the domain of attraction using a single Lyapunov function is too conservative. Using the concept of sequence of Lyapunov functions, the thesis proposes three methods to obtain the least conservative bounds for an initial local Lyapunov function. These general ideas are then applied to the aircraft example and the bounds on the perturbation of the aerodynamic database are presented.

This thesis deals with high angle of attack behaviour of a generic delta wing model aircraft. A high angle of attack wind tunnel database has been generated for this aircraft and based upon the bifurcation analysis of the data and the results of extensive simulations, it has been shown in the thesis that the post stall behaviour of this aircraft is both unstable and unpredictable. Unpredictability of aircraft behaviour arises from the fact that the aircraft response is oscillatory and divergent; the aircraft state trajectories do not settle down to any stable limit set and very often exceed valid aerodynamic database limits. This unpredictability of behaviour raises a major difficulty in the design of a procedure to recover the aircraft to normal flight regime in case the aircraft stalls and departs accidentally. A new methodology has been presented in this thesis to recover such unstable aircraft. In this methodology, a nonlinear controller is first designed at high angles of attack. This controller is connected by the pilot after the departure of the aircraft and the controller drives the aircraft to a well-defined spin condition. Thus, the controller makes the post stall aircraft behaviour predictable. Then a set of automatic recovery inputs is designed to reduce aircraft rotations and to lower the angle of attack. The present aircraft model is unstable at low angle of attack flight conditions as well and therefore to stabilize the aircraft to a low angle of attack level flight, another controller is designed. The high angle of attack controller is disconnected and the low angle of attack controller is connected automatically during the recovery process. The entire methodology is tested using extensive non-linear six degree-of-freedom simulations and the efficacy of the technique is established. The nonlinear controller that stabilizes the aircraft to a spin condition is designed using feedback linearization. The stability of a closed loop system obtained using feedback linearization is determined by the stability of the zero dynamics of the open loop plant. It has been shown in literature that the eigenvalues of the linearized zero dynamics are the same as the transmission zeros of the linearized plant at the equilibrium point. It is also well known that the location of transmission zeros of a linear system can be changed by the choice of outputs. In this thesis it is shown that if it is possible to reassign the outputs, then the feedback linearization based design for a linear system becomes very similar to a controller design for eigenvalue assignment. This thesis presents a new two-step procedure to obtain a locally stable and optimally robust closed loop system using feedback linearization. In the first step of this procedure optimal locations of the transmission zeros are found and in the second step, optimal outputs are constructed to place the system transmission zeros at these locations. The same outputs can then be used to construct nonlinear feedback for the nonlinear system and the resultant closed loop system is guaranteed to be locally robustly stable. The high angle of attack controller is designed using this procedure and its performance is presented in the thesis. The stabilized spin equilibrium point of the closed loop system is also shown to have a large domain of attraction. Having designed a locally robust stabilizing controller, the thesis addresses the problem of the evaluation of robustness of the stability of the equilibrium point in a nonlinear framework. The thesis presents a general method to construct bounds on the additive perturbations of the system vector field over a large region in the domain of attraction of a stable equilibrium point using Lyapunov functions. If the system perturbations lie within these bounds, the system is guaranteed to be stable. The thesis first proposes a method to numerically construct a Lyapunov function over a large region in the domain of attraction. In this method a sequence of Lyapunov functions are constructed such that each function in the sequence gives a larger estimate of the domain of attraction than the previous one. The seminal idea for this method is obtained from the existing literature and this idea is considerably generalized. Using this method, it is possible to numerically obtain a Lyapunov function value at each point in the domain of attraction, but the Lyapunov function does not have an analytical form. Hence, it is proposed to represent this function using neural networks. The thesis then discusses a new method to construct perturbation bounds. It is shown that the perturbation bounds obtained over a large region in the domain of attraction using a single Lyapunov function is too conservative. Using the concept of sequence of Lyapunov functions, the thesis proposes three methods to obtain the least conservative bounds for an initial local Lyapunov function. These general ideas are then applied to the aircraft example and the bounds on the perturbation of the aerodynamic database are presented.

La dengue circule en Polynésie française sur un mode épidémique depuis plus de 35 ans. Néanmoins, en dépit de la taille relativement faible de la population de Polynésie française, la circulation de la dengue peut persister à de faibles niveaux pendant de nombreuses années. L’objectif de ce travail de thèse est de déterminer si l'épidémiologie de la dengue dans le système insulaire de la Polynésie française répond aux critères d’un contexte de métapopulation. Après avoir constitué une base de données regroupant les cas de dengue répertoriés sur les 35 dernières années, nous avons réalisé des analyses épidémiologiques descriptives et statistiques. Celles-ci ont révélé des disparités spatio-temporelles distinctes pour l’incidence de la dengue des archipels et des îles, mais la structure de l'épidémie globale à l’échelle de la Polynésie française pour un même sérotype ne semble pas être affectée. Les analyses de la métapopulation ont révélé l'incidence asynchrone de la dengue dans un grand nombre d’îles. Celle-ci s’observe plus particulièrement par la différence de dynamique de l’incidence entre les îles plus peuplées et celles ayant une population plus faible. La taille critique de la communauté nécessaire à la persistance de la dengue n’est même pas atteinte par la plus grande île de Polynésie Française, Tahiti. Ce résultat suggère que la dengue peut uniquement persister grâce à sa propagation d’île en île. L'incorporation de la connectivité des îles à travers des modèles de migration humaine dans un modèle mathématique a produit une dynamique de la dengue davantage en adéquation avec les données observées, que les tentatives de modélisation traitant la population dans son ensemble. Le modèle de la métapopulation a été capable de simuler la même dynamique que les cas de dengue observés pour l'épidémie et la transmission endémique qui a suivi pour la période de 2001 à 2008. Des analyses complémentaires sur la différenciation de l'incidence de la maladie et de l'infection seront probablement instructives pour affiner le modèle de métapopulation de l'épidémiologie de la dengue en Polynésie française
Dengue has been epidemic in French Polynesia for the past 35 years. Despite the relatively small population size in French Polynesia, dengue does not disappear and can persist at low levels for many years. In light of the large number of islands comprising French Polynesia, this thesis addresses the extent to which a metapopulation context may be the most appropriate to describe the epidemiology and persistence of dengue in this case. After compiling a database of dengue cases over the last 35 years, we used a number of descriptive and statistical epidemiological analyses that revealed distinct spatio-temporal disparity in dengue incidence for archipelago and islands. But the global structure of the epidemics of the same serotype were not affected. Metapopulation analyses revealed asynchronous dengue incidence among many of the islands and most notably larger islands lagged behind the smaller islands. The critical community size, which determines dengue persistence, was found to exceed even the largest island of Tahiti, suggesting that dengue can only exist by island-hopping. Incorporation of island connectedness through patterns of human migration into a mathematical model enabled a much better fit to the observed data than treating the population as a whole. The metapopulation model was able to capture to some extent the epidemic and low level transmission dynamics observed for the period of 2001-2008. Further analyses on differentiating incidence of disease and infection will likely prove informative for the metapopulation model of dengue epidemiology in French Polynesia

Airport disruption is a common situation and is expected to happen from time to time which can result from external and internal situations/factor. This dissertation aims to analyze the perception of passengers regarding disruption situations in the Lisbon Humberto Delgado Airport and to propose strategies and actions undertaken by the airport and the airline companies to improve the passenger experience and customer/passenger satisfaction. If disruption is foreseen to happen, in certain situations/factors, it can be predicted and planned/corrected in advance to diminish its effects. Also, when a disruption situation arises, the management process that is developed to provide a high level of satisfaction for the passengers is quite complex and challenging for the airport operator. Even so, the airport operator only has partial control of all the processes that make up the final offered service or product. The main research questions guiding this study are: aren’t passengers expecting from the airport management mechanisms to prevent this kind of situations? How can the airport improve passengers experience and offer customer value at the same time in a situation of disruption? A combined qualitative (personal deep interview with the Lisbon Airport Deputy Director and the Lisbon Hub Manager from the Portuguese flag company – TAP) and quantitative methodology (survey addressed to the passengers that used the Airport LHD in the summer of 2018, where 471 questionnaires were accepted). By analysing the obtained results, it was possible to demonstrate that the causes of disruption affect the level of satisfaction of the passengers as well as the actions taken by the airport and the airline. The level of information (high or low) that the passengers receive causes their level of satisfaction or unsatisfaction to increase or decrease with the operators.
A disrupção nos aeroportos é uma situação comum e expectável de tempos a tempos, tanto pode resultar de situações/factores internos e externos. Esta dissertação tem como objetivo analisar a percepção dos passageiros sobre situações de disrupção no Aeroporto de Lisboa Humberto Delgado e propor estratégias e acções empreendidas pelo Aeroporto e pelas companhias aéreas para melhorar a experiência do passageiro e a satisfação do cliente/passageiro. Se houver previsão que venha a ocorrer uma situação de disrupção, em determinadas situações/factores, esta pode ser prevista e planeada/corrigida com antecedência de modo a diminuir os seus efeitos. Além disso, quando surge uma situação de disrupção, o processo de gestão desenvolvido para proporcionar um elevado nível de satisfação aos passageiros é bastante complexo e desafiante para o gestor do aeroporto. Mesmo assim, o gestor do aeroporto tem controlo parcial de todos os processos que compõem o serviço ou produto final oferecido. As principais questões de pesquisa que guiaram este estudo foram: será que os passageiros não esperam mecanismos de gestão por parte do aeroporto para gerir este tipo de situações? Como pode o Aeroporto melhorar a experiência dos passageiros e ao mesmo tempo oferecer valor ao cliente numa situação de disrupção? Uma metodologia qualitativa (entrevista presencial com o director do Aeroporto de Lisboa e o director do Hub de Lisboa da companhia de bandeira Portuguesa – TAP) e quantitativa combinada (questionário dirigido a passageiros que utilizaram o Aeroporto LHD no verão de 2018, em que 471 questionários foram validados). Pela análise dos resultados obtidos, foi possível demonstrar que as causas de disrupção afectam o nível de satisfação dos passageiros assim como as acções tomadas pelo aeroporto e pela companhia aérea. O nível de informação (alta ou baixa) que os passageiros recebem faz com que a sua satisfação ou insatisfação aumente ou diminua com os operadores.

This thesis explores the relationship between empathy and parenting in a sample of fathers recovering from addiction. It considers whether and how the development of empathic parenting skills can facilitate changes in emotion regulation and positive attachment to their children, and considers the implications of focusing on supporting men as fathers for their recovery. Previous research has identified reduced capacities for empathy and emotion regulation in people experiencing addictions compared to those without addictions. The present study investigated firstly whether differences in attachment, empathy and emotion regulation would correlate with the presence or absence of addiction in a sample of fathers. Having established this to be the case, particularly with respect to empathy and emotion regulation, phase 2 of this study explored whether training in empathic parenting skills could help fathers undergoing treatment for addictions to improve their relationships with their children, their perceptions of themselves as fathers, and their sense of wellbeing. While the link between addictions in fathers and diminished health outcomes in their children is well established, there has been little research to date that has studied the perspectives of fathers themselves during the recovery process. Accordingly, this research also sought to explore the parenting experiences of a sample of fathers as they recovered from addictions in two residential rehabilitation centres in Sydney, Australia, in 2013. The focus on the men’s experiences encompassed two key questions: How do fathers recovering from addictions experience changing relationships with their children? What other changes take place for these recovering fathers throughout the parenting program? The two phases of this research were designed as a mixed-method study, consisting of an initial quantitative survey of 169 fathers who responded to questionnaires that assessed their attachment to their children, their difficulties with emotion regulation, their mental and physical health symptoms, and their social, cognitive and affective empathy. The following second phase was designed as an in-depth multiple case study that involved seven fathers in the two residential rehabilitation centres. The results were encouraging, as each of the seven fathers told of positive change in their lives. Through the recovery process the men described themselves and their children differently, as their children became more important to them and their confidence grew in those relationships. It was clear that fatherhood was a significant concern for these men, and their relationships with their children a central motivator for them. The men were thus able to develop greater emotion regulation themselves through learning about how their children learn to manage emotions and how they as fathers can help, in addition to emotion regulation exercises focusing on their own wellbeing as fathers. The change in the fathers’ comments and questionnaire responses between the beginning and end of the parenting program also showed evidence of closer empathy-related attachment (‘empathic connection’) to their children, which is thought to underlie both the recovery process and their relationships with their children. The implications of these results are profound. Firstly, this study has found that men with major histories of addiction still have the ability, with positive support and improved emotional awareness, to form an empathic connection with their children. Secondly, providing a means for these men to focus on fatherhood within their recovery program has also helped facilitate a greater awareness of being positive role models for their children. This in turn led some of the fathers to report that their children showed not only more respect towards them, but perhaps most importantly, improved wellbeing.

Currently, it is uncertain how well a typical ground-based simulator's hexapod motion system can simulate the aggressive motion during airplane upset. To address this issue, this thesis attempts to improve simulator motion for upset recovery simulation by defining new motion fidelity criteria, implementing body frame filtering, and improving an existing adaptive motion drive algorithm. The successfully improved adaptive algorithm was used to conduct a paired comparison experiment to study the effects of trade-offs between translational and rotational motion cues on pilot subjective fidelity and upset recovery performance. Analysis of the experimental data found that pilots generally rejected motion with false lateral cues and they preferred the presence of rotational cues for moderate roll angles. Also, performance analysis suggested that roll cues helped improve lateral control. Overall, pilots preferred to have simulator motion during upset simulation and significant improvements in performance were observed when simulator motion was present.

碩士
逢甲大學
企業管理所
100
It is getting difficult to manage and maintain the brand because the commercial competition is becoming fiercer. Corporations often receive a lot of customer complaints and dissatisfaction by dint of employees’ neglect. Besides, service failures happen to international companies because of the external environment factors that enterprise are unable to control, such as earthquake, typhoon or flood, result in factories stopped working effectively. It is worth discussing this issue, that how enterprises apply proper recovery method when facing different crisis in order to gain customer satisfaction and perceived justice, and to gain customers confidence toward the enterprises. This study takes airline industry as an example and subjects are the passengers who had service failure experiences. The purpose is to exam the impacts of airline crisis incident and methods of service recovery on customer brand attitude. Also, it exams the moderating effect of flight frequency. In this study, two-stage design of the questionnaire is adopted. In the first phase of the questionnaire, we collect information regarding the customer responses and satisfactions when airlines using different service recovery measures. In the second phase of the questionnaire, under different crises, how the airlines respond to the customers. Do methods of service recovery of airlines affect the satisfaction, perceived justice and brand attitude? The results indicate that the customer will not blame on enterprise when crisis incident is which the enterprise is unable to control, and enterprise is better to assist passengers, such as replacing flight or assisting the transit hotel. When crisis incident is which enterprise is able to control, both customer satisfaction and perceived justice are significantly reduced when airlines applying any service recovery method. It is better for enterprise to compensate. If taking combination methods of service recovery, the satisfaction and perceived justice are higher than when applying only single method of service recovery. The result also shows that passengers flight frequencies has moderating effect between uncontrollable crisis incidents and service recovery; passengers flight frequencies has no moderating effect between controllable crisis incidents and service recovery. Customer satisfaction and perceived justice after recovery have significant positive effects on brand attitude.

In team sports, the competition season requires a balance between training and recovery. To assist in this process, both internal and external load are quantified. External load can be measured using Global Positioning Systems (GPS) and sensors such as accelerometers. Internal load is commonly identified through session rating of perceived exertion (sRPE), biochemical response in addition to changes in performance tests. However, little is known about the interaction between training load, the response to this load, and performance. Study 1 determined the response of countermovement jump (CMJ) performance and salivary testosterone and cortisol to low, medium and high accelerometer derived PlayerLoad™ following football match play. Flight time:contraction time (FT:CT) was the most sensitive CMJ metric, with a dose-response reduction for 42h post-match. There were post-match increases in testosterone and cortisol irrespective of PlayerLoad™ level, and substantial variability which limits the usefulness of hormonal markers. Study 2 assessed the impact of training and competition load throughout a professional football season on FT:CT, testosterone, cortisol and testosterone:cortisol and match performance. The largest effects of internal load on performance occurred in the 3- to 14-day pre-match window. An association between increased load and lower rating of performance was identified in defenders, whilst strikers and wide midfielder’s performance rating was higher with higher load. Change in load did not substantially impact FT:CT or the hormonal response, and there was limited impact of these measures on performance. Study 3 examined the use of a commonly used football training drill; small sided game (SSG), for measurement of neuromuscular fatigue (NMF). Whilst high weekly load increased accelerometer derived metrics during the SSG, these modifications did not appear to be fatigue related. Lower FT:CT compared to baseline, was related to reductions in accelerometer derived variables during the SSG. The reductions in FT:CT and accelerometer variables in the SSG were followed by the same modifications to match activity profile. Therefore, a standardised SSG game may be a useful tool for the assessment of NMF. This thesis provides insights into the links between training and competition load, the response to that load, and the impact on performance in elite male football players. The results offer practitioners useful approaches to monitor athletes and maximise their performance. Finally, this thesis demonstrates the utility of an SSG for the assessment of NMF.

This dissertation focused on the development of mass spectrometric methodologies, separation techniques, and engineered devices for the optimal analysis of complex mixtures relevant to the energy sector, such as alternative fuels, petroleum-based fuels, crude oils, and processed base oils. Mass spectrometry (MS) has been widely recognized as a powerful tool for the analysis of complex mixtures. In complex energy samples, such as petroleum-based fuels, alternative fuels, and oils, high-resolution MS alone may not be sufficient to elucidate chemical composition information. Separation before MS analysis is often necessary for such highly complex energy samples. For volatile samples, in-line two-dimensional gas chromatography (GC×GC) can be used to separate complex mixtures prior to ionization. This technique allows for a more accurate determination of the compounds in a mixture, by simplifying the mixture into its components prior to ionization, separation based on mass-to-charge ratio (m/z), and detection. A GC×GC coupled to a high-resolution time-of-flight MS was utilized in this research to determine the chemical composition of alternative aviation fuels, a petroleum-based aviation fuel, and alternative aviation fuel candidates and blending components as well as processed base oils.

Additionally, as the cutting edge of science and technology evolve, methods and equipment must be updated and adapted for new samples or new sector demands. One such case, explored in this dissertation, was the validation of an updated standardized method, ASTM D2425 2019. This updated standardized method was investigated for a new instrument and new sample type for a quadrupole MS to analyze a renewable aviation fuel. Lastly, the development and evaluation of a miniaturized coreflood device for analyzing candidate chemically enhanced oil recovery (cEOR) formulations of brine, surfactant(s), and polymer(s) was conducted. The miniaturized device was used in the evaluation of two different cEOR formulations to determine if the components of the recovered oil changed.