Diss.--Fachbereich Rechtswissenschaft I--Hamburg--Universität, 1992.

Thesis (MEng)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: This thesis presents research contributing towards the automatic control of formation flight for commercial airliners. The motivation behind this research is to ultimately reduce fuel consumption of the trailing airliner through the utilisation of the aerodynamic coupling interactions between the trailing airliner and the wake vortices of the leading airliner. A traditional model for an airliner in isolated flight is developed and expanded to include formation flight interactions as functions of the vertical and lateral separation between the trailing and leading airliners. A trim analysis is done, and resulting actuator trims are presented over ranges of lateral and vertical separation. Regions of reduced throttle setting are identified, as well as risks and challenges for maintaining formation within these regions. These regions comprise of a potentially risky and challenging region, coined the "sandwich region"; as well as a safer, more practically viable region, coined the "outer region". The former is a narrow region sandwiched between two regions that are untrimmable with respect to maximum aileron deflection, whereas the latter is only constrained by an inboard untrimmable bound, but has less significant drag reduction. Subsequently, a state space representation is constructed, and a linear dynamics analysis follows. It is determined that the trimmed, uncontrolled trailing airliner is naturally unstable; hence a flight control system is required for stability. Furthermore, the analysis revealed that the dynamics stay essentially constant, especially for conventional modes, within the outer region. In the sandwich region however, the dynamics change much more drastically. Next, a control system for the conventional airliner is designed based on the available information of current representative fly-by-wire systems; and its performance is analysed in formation flight scenarios by means of both linear and non-linear simulations. It is found that, given sufficiently high control law gains, particularly for lateral controllers, the conventional architecture is sufficient for maintaining formation. Additional structures are suggested, such as saturation elements to limit the lateral separation rate and acceleration; and a state machine controller, with states for entering and exiting the wake vortices. Following this, a robustness analysis was done by once again evaluating the linear dynamics over ranges of lateral and vertical separation; this time with the flight controllers augmented into the linear models. The robustness analysis proved that the controllers are robust against lateral and vertical separation perturbation, at least in the outer region. Finally, a series of non-linear simulations prove the success of the control system in maintaining formation in various atmospheric turbulence conditions. Furthermore, the trailing airliner consistently has a reduced throttle setting, though with greater dynamic throttling compared to the leading airliner. Lastly, it is determined that the standard deviations of the control surface defection of the trailing airliner are in the same order of magnitude as those of the leading airliner in simulations with moderate turbulence. Interestingly, it is found that the elevator deflection of the trailing airliner has a lower standard deviation than that of the leading airliner, possibly due to the leading airliner carrying the burden of regulating the formation's altitude. / AFRIKAANSE OPSOMMING: Hierdie tesis handel oor navorsing wat 'n bydrae maak tot die outomatiese vlugbeheer van kommersiële passasiersvliegtuie in formasievlug. Die navorsing is gemotiveer deur die potensiële vermindering in die brandstofverbruik van die volgervliegtuig wat verkry kan word deur voordeel te trek uit die aerodinamiese koppeling tussen die volgervliegtuig en die nasleurvortekse van die voorste vliegtuig. 'n Tradisionele vlugmeganika model vir 'n passasiersvliegtuig is ontwikkel en uitgebrei om formasievluginteraksies in te sluit, as funksies van die vertikale en laterale skeidingsafstande tussen die volgervliegtuig en die voorste vliegtuig. 'n Ewewig-analise is uitgevoer, en die nodige ewewig-instellings is bereken oor die bereik van moontlike laterale en vertikale skeidingsafstande. Twee gebiede van verminderde enjin-krag instellings is gedentifiseer, en die risikos en uitdagings verbonde aan formasievlug in hierdie gebiede is beskou. Twee gebiede is uitgeken: 'n uitdagende, potensieel gevaarlike gebied, genoem die "sandwich" of "ingeperkte" gebied; en 'n veiliger, meer lewensvatbare gebied, genoem die "outer" of buitenste gebied. Die "ingeperkte" gebied is 'n baie nou gebied wat ingedruk is tussen twee ewewig-oninstelbare gebiede, waar aileron de eksie instellings vereis word wat die maksimum moontlike de eksies oorskry. Die "buitenste" gebied is 'n gebied wat net aan die binnekant begrens word deur 'n ewewig-oninstelbare gebied, maar wat nie so 'n groot besparing in brandstofverbruik bied as die "ingeperkte" gebied nie. Vervolgens is 'n toestandsveranderlike voorstelling van die vlugdinamika afgelei, en 'n dinamiese analise is uitgevoer. Die dinamiese analise het gewys dat die ewewig-ingestelde, onbeheerde vliegtuig natuurlik onstabiel is, en dat 'n vlugbeheerstelsel benodig word om vlugstabiliteit te verseker. Daarby het die analise ook onthul dat die vlugdinamika baie min verander oor die bereik van die "buitenste" gebied, maar dat die vlugdinamika baie meer drasties verander oor die bereik van die "ingeperkte" gebied. 'n Konvensionele vlugbeheerstelsel vir die vliegtuig is volgende ontwerp, gebaseer op beskikbare inligting oor die argitektuur van tipiese "fly-by-wire" beheerstelsels wat tans op passasiersvliegtuie gebruik word. Die prestasie van die konvensionele vlugbeheerstelsel in formasievlugtoestande is ontleed deur middel van beide lineêre en nie-lineêre simulasies. Die simulasies het gewys dat die konvensionele vlugbeheerargitektuur in staat is om formasievlug te handhaaf, gegee dat voldoende hoë beheeraanwinste gebruik word. Bykomende strukture is voorgestel, insluitendend versadigingselemente om die koers en versnelling van die laterale skeidingsafstand te beperk; en 'n toestandsmasjien-beheerder, met toestande om die nasleurvortekse binne te gaan en te verlaat. 'n Robuustheidsanalise is ook gedoen, deur die geslotelusdinamika met die beheerders ingesluit te analiseer oor die bereik van laterale en vertikale skeidingsafstande. Die robuustheidsanalise het gewys dat die beheerders wel robuust is oor die bereik van beide laterale en vertikale skeidingsafstande, ten minste in die "buitenste" gebied. Ten slotte is 'n omvattende reeks nie-lineêre simulasies uitgevoer om die vermoë van die vlugbeheerstelsel om formasievlug te behou te bevestig in 'n verskeidenheid van turbulensietoestande. Die simulasies het verder gewys dat die volgervliegtuig deurgaans 'n verminderde enjin-krag instelling het, maar met aansienlik meer dinamiese enjin-krag instelling variasies vergeleke met die voorste vliegtuig. Laastens het die simulasies gewys dat die standaard afwykings van die volgervliegtuig se beheeroppervlakde eksies van dieselfde ordegrootte is as dié van die voorste vliegtuig. Interessant genoeg is bevind dat die elevator defleksies van die volgervliegtuig 'n laer standaardafwyking het as dié van die voorste vliegtuig, waarskynlik omdat die voorste vliegtuig die groter las dra om die formasie se hoogte te reguleer.

Cette thèse, fondée sur une enquête ethnographique, est consacrée aux employés de la SNCF qui travaillent en gare, « au contact de la clientèle ». Figures familières des voyageurs, les agents de vente, d‟accueil et d'escale ferroviaire voient leur activité professionnelle évoluer autour d'injonctions relatives à la « qualité de service » rendu, à la « satisfaction client » et au respect d‟objectifs comptables. Des dimensions qui sous-tendent notamment le renouvellement constant d‟un ensemble de normes encadrant leur travail et leur comportement. Cette thèse vise ainsi à mettre en évidence le fait que, bien qu'étant « une réalité ancienne » [Finez, 2013], la régulation marchande qui s'opère à la SNCF est une réalité multiforme, avec pour corolaire des réformes managériales qui redessinent progressivement les contours de l'activité des agents en gare, exigeant d'eux un « travail commercial ». Ces évolutions conduisent à interroger parallèlement le regard qu'ils portent sur ce rôle « commercial » et, plus généralement, la manière dont ces agents perçoivent leur condition professionnelle dans une entreprise publique en mutation.Ce travail s‟inscrit dans le sillage d'un ensemble d'études menées au sein d'entreprises et administrations publiques qui ont mis en exergue les transformations intervenues suite à l'introduction et à la généralisation de dispositifs d'organisation et de gestion appliqués dans le secteur privé. L'objectif est ainsi d'analyser les recompositions professionnelles mais aussi sociales que les exigences commerciales et gestionnaires de la SNCF entraînent. / This thesis, based on an ethnographic survey, focus on SNCF employees working at therailway station, “in contact with customers”. Sales, reception and railways stopover agents,who are the familiar figures of the travelers, see their professional activity evolving accordingto injunctions towards the quality of service returned to the customers, customer satisfactionand respect of sales target. Consequently, the norms around their work tasks and behaviorsare constantly changing due to those types of injunctions. This thesis aims at highlightingthat, despite being “an ancient reality” [Finez, 2013], the trade policy of the state-ownedcompany SNCF is an ongoing reality. It leading to managerial reforms that reshape theactivity of those previously mentioned agents with an important “commercial” dimension. Asa consequence, it is also important to question agents about their option regarding their“commercial” role, and, more generally, about the way they perceive their professionalcondition in a public company undergoing changes. This work falls in with a group of studies conducted in state companies and administrations which underline the changes occurred after the insertion and spread of organizational and managerial measures applied in the private sector. The purpose of this work is therefore to study the professional and social reconfigurations caused by the SNCF commercial and managerial demands.

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