• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 38
  • 24
  • 9
  • 4
  • 3
  • 3
  • 2
  • 2
  • 1
  • 1
  • 1
  • Tagged with
  • 99
  • 18
  • 18
  • 14
  • 12
  • 11
  • 9
  • 8
  • 8
  • 7
  • 7
  • 7
  • 7
  • 7
  • 7
  • 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.
91

Návrh repliky letounu L-40 "Meta Sokol" - základní rozměry - technologie / Replica design of Aircraft "Meta Sokol" - Basic dimensions - technology

Lipková, Alica January 2008 (has links)
The object of the diploma thesis is a preparation of fundamentals for realization for replica of the aircraft L-40 „Meta Sokol“ matching the requirements of Certification Specification for Very Light Aeroplanes (CS-VLA). The preamble of the work deals with the changes made on the original aircraft necessary to satisfy the criterias of the above-mentioned specification. One of the main contents of the first part of the thesis is the definition of replica’s basic dimensions and preparation of aerostatic fundamentals, including longitudinal stability control. As next a suitable engine is chosen and calculation of corresponding performances is made. A detailed weight analysis and a determination of centre of gravity position (c.g. position), important for solving the stability of an airplane, is also presented. Finally, a brief description of the manufacturing process of individual components and also factors influencing the technology are discussed.
92

Prodloužení životnosti letounů ZLIN Z 126 a 226 / Safe-life extension program for ZLIN Z 126 and 226 airplanes

Jančář, Milan January 2012 (has links)
This master's thesis discusses the possibilities of safe-life extension program for ZLIN Z 126 and 226 airplanes, which despite their age and long-end production are still widespread and popular not only in the Czech Republic. The age of these aircraft is also related to the fact, that some aircraft are already approaching its border life, so there is an interest for the longest possible technical and legislative airworthiness. As mentioned in my bachelor's thesis, during the existence of this model series, there was no major damage occurred, except for sporadic exfoliation corrosion of wing flanges. Experience with maintenance of this aircraft points to certain underestimation of the current 5500hrs lifetime and it is obvious to suggest possible steps to increase the current limit. The thesis is therefore considered in this context the possibility of producing new wing flanges made of another material, performed the calculation for wing fatigue exchanged with flanges and designed technological process of this exchange, so that ZLIN Z 126 and 226 airplanes can be safely operated in the future.
93

Návrh řídicího algoritmu pro stabilizaci letadla / Control algorithm for aircraft stabilization

Novák, Pavel January 2013 (has links)
Master’s thesis: "Design of the control algorithm for aircraft stabilization" summarizes aircraft aerodynamics knowledge, from which nonlinear mathematical model of the aircraft and propeller propulsion system are created. Design of the control algorithm for angle position stabilization (for longitudinal motion) and the control algorithm for “Flight Path Angle hold“ and “Flight Level Change” modes is also presented here. Designed control algorithms are tested within the simulation of the real atmosphere at the end of the thesis.
94

Ocenění výše škody způsobené pádem sportovního letadla na rodinný dům v obci Žešov / Valuation of damage caused by the fall of sport aircraft on a house in the village of Žešov

Krutílková, Eliška January 2015 (has links)
The theme of this master´s thesis is determine the new price of a house in Prostějov, district Žešov, cost method of valuation, current price of a house before insured event, description of the insured event (fall of the airplane Zlin Z-326 M), determining the amount of insurance payment for the harm caused of the insured event and again determine the current price of a house after insured event. Result above operations is evaluation effect of executed corrections after the insured event to the house value.
95

Fault Detection in Permanent Magnet Synchronous Motors using Machine Learning

Lennartsson, Alexander, Blomberg, Martina January 2021 (has links)
In the aviation industry, safety and robustness are the number one priorities, which is why they use well-tested systems such as hydraulic actuators. However, drawbacks such as high weight and maintenance have pushed the industry toward newer, electrical, actuators that are more efficient and lighter. Electrical actuators, on the other hand, have some reliability issues. In particular, short circuits in the stator windings of Permanent-Magnet SynchronousMotors (PMSMs), referred to as Inter-Turn Short Faults (ITSFs), are the dominating faults, and is the focus of this thesis. ITSFs are usually challenging to detect and often do not become noticeable until the fault has propagated, and the motor is on the verge of being destroyed. This thesis investigates the possibility of detecting ITSFs in a PMSM, at an early stage when only one turn is shorted. The method is limited to finding the faults using ML algorithms. Both an experiential PMSM and a simulated model of the experimental PMSM, with the ability to induce an ITSF, were used to collect the data. Several Machine Learning (ML) models were developed, and then trained and tested with the collected data. The results show that four of the tested ML models, being: Random Forest, Gaussian SVM, KNN, and the CNN, all achieve an accuracy exceeding 95%, and that the fault can be found at an early stage in a PMSM with three coils connected in parallel in each phase. The results also show that the ML models are able to identify the ITSF when the simulated data is downsampled to the same frequency as the experimental data. We conclude that the ML models, provided in this study, can be used to detect an ITSF in a simulated PMSM, at an early stage when only one turn is shorted, and that there is great potential for them to detect ITSFs in a physical motor as well.
96

Modeling and test of loop heat pipes for civil and military avionic applications / Modélisation et tests d’une boucle diphasique capillaire (LHP) pour applications avioniques civile et militaire

Hodot, Romain 15 December 2015 (has links)
Dans les années à venir, l’industrie de l’aéronautique doit améliorer le contrôle thermique des composants et modules hautement intégrés. Les approches de refroidissement standard, utilisant l’air forcé ne sont plus utilisables. Il est donc nécessaire de développer de nouvelles technologies capables d’offrir des solutions compatibles avec ces nouvelles problématiques. Une revue bibliographique approfondie est présentée pour montrer les solutions existantes pour l’avionique. Les systèmes à changement de phase, tels que les boucles diphasiques capillaires (LHPs), sont très attractifs puisqu’ils peuvent être utilisés pour transporter la chaleur vers une grande surface d’un radiateur qui dissipera la chaleur vers le milieu ambiant. Une première famille de LHP, conçue et réalisée par la compagnie Atherm, et remplie avec du méthanol, est décrite. Deux autres familles de LHP sont également présentées. La première a été réalisée par la société ATHERM et a un condenseur et des lignes de transports modifiés, afin d’être intégrée sur une carte électronique existante. La deuxième famille, a été conçue et réalisée par l’Institut of Thermal Physics (ITP), sur la base de spécifications similaires. Un banc d’essai expérimental est conçu et réalisé pour tester ces systèmes. Les effets de la charge en fluide, baïonnette, et mèche secondaire, sont observés. Des tests d’orientation et d’accélération sont réalisés sur des LHPs intégrées dans un rack aéronautique. Même une certaine sensibilité aux orientations et accélérations est observée, les LHPs fonctionnement toujours jusqu’à l’accélération maximale testée de 6 G. Un modèle stationnaire d’une boucle diphasique basé sur une approche à plusieurs échelles est développé. Plusieurs niveaux de complexité et de précision peuvent être sélectionnés pour le modèle des composants individuels de la boucle, allant du modèle nodal au modèle 3D. Le modèle est validé avec les données expérimentales. Un bon accord entre les simulations numériques et les résultats expérimentaux est obtenu. Les résultats numériques montrent que la charge de fluide dans le réservoir affecte le comportement thermique de la LHP en modifiant la répartition des flux de chaleurs. Des gradients de température importants sont observés dans la plaque du condenseur, et un nouveau tracé de la ligne condenseur est proposé. Plusieurs modifications de l’évaporateur sont analysées. La diminution la plus importante de la résistance thermique de l’évaporateur est obtenue par une bonne disposition des rainures axiales de la mèche, associée à une semelle optimisée, ou à des rainures radiales. / In the coming years, the avionics industry will have to improve the thermal control of both existing and emerging highly integrated electronic components and modules. The standard cooling approaches using forced air are no longer applicable. It is necessary to develop new technologies being able to offer solutions compatible with those new problematic. An extensive literature review is presented to show the existing cooling solutions for avionics. Two-phase passive systems, such as LHPs are very attractive as they may be used as heat spreader, associated with a classical heat sink to dissipate the heat. A first family of LHP, designed and manufactured by the ATHERM Company and filled with methanol as the working fluid is described. Two other LHP families are also presented. The first one was manufactured by ATHERM and has modified condenser and transport line shapes, in order to be integrated into an existing electronic card. The second one was manufactured and designed by the Institute of Thermal Physics, on the same specification basis. An experimental setup is designed and built to test these LHPs. The effects of fluid fill charge, bayonet and secondary wick are observed. Orientation and acceleration tests are conducted on LHPs integrated within an avionic rack. Even if the LHPs exhibited sensitivity to orientation and acceleration, no failure of the LHP was observed up to the maximum applied acceleration (6 G). A steady state model of LHP based on a multi-level approach is developed. Various levels of complexity and precision can be selected for the model of the individual component, going from the nodal to the 3D model. The model is validated with experimental data from the laboratory tests. A good agreement is achieved between the experimental and the numerical data. The numerical results show that the fluid fill charge within the reservoir affects the thermal behavior of the LHP, by modifying the heat flux distribution. High temperature gradients are highlighted in the condenser plate and a redesign of its shape is proposed. Various modifications of the evaporator design are considered. The most important decrease of the evaporator thermal resistance is brought by a good disposition of the axial vapor grooves associated with an optimized saddle shape or radial vapor grooves.
97

A business analysis of the South African domestic commercial air transport market : low-cost carriers and full-service carriers in the context of the business environment and passenger behaviours

Diggines, Colin Neville 31 July 2017 (has links)
This study attempted to establish the travel behaviours and choice criteria of the South African domestic air passenger and how they differed between low-cost carriers (LCCs) and full-service carriers (FSCs). The study was quantitative and used structured questionnaires to collect data via personal interviews. Descriptive and inferential techniques were used to analyse the data, including a binomial logistic regression to identify predictors of model choice. Analysis This study attempted to establish the travel behaviours and choice criteria of the South African domestic air passenger and how they differed between low-cost carriers (LCCs) and full-service carriers (FSCs). The study was quantitative and used structured questionnaires to collect data via personal interviews. Descriptive and inferential techniques were used to analyse the data, including a binomial logistic regression to identify predictors of model choice. Analysis showed that passengers had a limited understanding of the functioning of the models. This results in consumer perceptions and expectations being discordant with the true differences. In distinguishing between models, LCC passengers rate LCCs more favourably than FSC passengers, but both rate FSCs higher than LCCs. This shows the need of consumers to have the features and services of the FSCs. Amongst the key findings was the absolute importance of price to the passengers on both models when purchasing the ticket. The analysis showed that LCC passengers are highly price sensitive and show loyalty to the lowest price (not airline model). It was apparent that frequent flyer programmes (FFP), or linkages to 3rd party loyalty programmes, for LCCs need to be reconsidered. Younger LCC passengers especially, indicated a need for a simple FFP to receive some form of ‘reward’, as well as benefits traditionally only offered by FSCs. FSC passengers show a greater degree of loyalty and less fare sensitivity. This provides the FSCs with a degree of fare flexibility and the opportunity to move their loyal, less price-sensitive consumers up the price curve to maximise revenue. It was shown that, in distinguishing themselves from FSCs, it is important that LCCs are perceived as being more affordable than FSCs and are offering a value-for-money service. In essence, LCCs have to defend their positioning by (i) ensuring that their fares are not perceived to be as high as a FSCs and (ii) watching that the FSC fares are not declining to a level where FSCs are perceived as being as cheap as a LCC. For LCCs, brand building strategies around issues other than fare need to be devised, with attention paid to identifying determinant factors. / Business Management / D. Com (Business Management)
98

Galerie letecké techniky a tradic letectví na letišti Medlánky v Brně / Gallery aviation technology and traditions of aviation at the airport Medlánky in Brno

Bělehradová, Věra January 2016 (has links)
Sport Airport complex Brno-Medlánky is nestled in the undulating hilly terrain in fields just beyond populated areas in Brno-Medlánky. The history of the airport dates back to 1924 when it was built the first wooden hangar for training purposes glider flights. Current state urban of airport is orderless. The aim is to streamline the complex and give it the order, allowing easy and efficient orientation in the space. The main intervention was the creation of a new central building - Aviation Museum. The concept of the design is based on the division of the whole area into two branches - communication axes, based on the mass preserved historic wooden hangars. Between the two communication arms is inserted a central axis on which is located the heart of the complex - Aviation Museum. It is a building organic form, inspiring axially symmetric wingspan (bird, airplane, beetle). It is this symmetry axis of the building creates a view towards building on the runway. Mass of the building used by the sloping terrain and is partially sunk under the ground. Building volume follows an upward slope from the outside and blends with the surrounding terrain. The internal layout consists of three floors, one of them is completely sunk below ground level and second half. The main entrance to the gallery is located in the uppermost floors, the direction of the exhibition is therefore directed downwards into the basement. The exposition is divided into six parts: RC models exposure, gliders exposure, powered aircraft exposure, screening room, children's exposure and air trainers. Other areas consist of building technical facilities. In the basement there is a workshop with aircraft lift, with the possibility of placement unexposed aircrafts. The supporting system of the building consists of two parts: reinforced concrete tubs and arched steel structure with a span of 50m.
99

Odhad Letových Parametrů Malého Letounu / Light Airplane Flight Parameters Estimation

Dittrich, Petr Unknown Date (has links)
Tato práce je zaměřena na odhad letových parametrů malého letounu, konkrétně letounu Evektor SportStar RTC. Pro odhad letových parametrů jsou použity metody "Equation Error Method", "Output Error Method" a metody rekurzivních nejmenších čtverců. Práce je zaměřena na zkoumání charakteristik aerodynamických parametrů podélného pohybu a ověření, zda takto odhadnuté letové parametry odpovídají naměřeným datům a tudíž vytvářejí předpoklad pro realizaci dostatečně přesného modelu letadla. Odhadnuté letové parametry jsou dále porovnávány s a-priorními hodnotami získanými s využitím programů Tornado, AVL a softwarovéverze sbírky Datcom. Rozdíly mezi a-priorními hodnotami a odhadnutými letovými paramatery jsou porovnány s korekcemi publikovanými pro subsonické letové podmínky modelu letounu F-18 Hornet.

Page generated in 0.0477 seconds