Dissertationen zum Thema „Main gear“

Experimental measurements and numerical simulations were conducted on a simplified main landing gear model that consists of a leg-door, and a main strut in a parallel configuration. The effects of varying the leg-door angle of attack, and the gap distance between the two elements, were initially studied by two-dimensional and low-order numerical simulations, using the unsteady Reynolds-Averaged Navier-Stokes equations. The strut diameter was specified to the same diameter as a full-scale main landing gear, and simulated under a free-stream Mach number of 0.2, and a Reynolds number based on the cylinder diameter of 1:7 x 106. Further three-dimensional and high-order numerical simulations were conducted on models with a constant gap distance of 8.7% of the cylinder diameter. The high-order solver evaluates the three-dimensional Navier-Stokes equations in the full-conservation form, with the Zonal Detached-Eddy Simulation model. The fidelity of the numerical solver was improved in two parts. Firstly, an Eigenvalue analysis for a multiple-block environment was developed to optimise the combination of spatial and filtering schemes for maximum grid resolution that is numerically stable. Secondly, a grid quality metric, which correlates strongly to the solution accuracy, was developed. A validation database of experimental measurements on a tripped 26% scale interaction model, at a free-stream Mach number of 0.09, and a Reynolds number based on the cylinder diameter of 2 x 105, was developed at the 2:1 m x 1:5 m wind tunnel at the University of Southampton. The experimental and numerical results show that the wake generated by the interaction model is dominated by low frequencies that correspond to the vortex shedding modes of the cylinder, and the door. As the door angle is increased from 0 to 10.7 degrees, the intensity of the cylinder shedding mode decreased. The sound pressure levels of the radiated noise were calculated using the FW-H method. The dominant noise source is a compact dipole, which reduced in strength as the door angle was increased.

This diploma thesis deals with the landing gear design of the small two-seat aircraft. The introduction focuses on the conceptual gear design and shock absorber computational dynamic characteristic model. The practical part is focused on the landing gear construction according to the selected parameters based on the conceptual and computational model. The diploma thesis ends with strength calculations and production documentation.

This thesis presents a bifurcation and numerical continuation study into the occurrence of shimmy instability in an aircraft main landing gear (MLG) of single side-stay, dualwheel design. The dynamics are expressed in terms of three rotational degrees of freedom (Dofs) aligned with the side-stay plane, and a fourth translational DoF representing compression of the main strut. These DoFs are modelled by oscillators that are coupled directly through the geometric configuration of the system, as well as through the tyre/ground interface. Using this representation of the MLG system we focus in this thesis on the nonlinear effects of geometric orientation and mechanical freeplay employing bifurcation analysis techniques to highlight their effects on the MLG stability. First, a changing side-stay orientation angle is investigated. Shimmy is studied by means of a two-parameter bifurcation analysis in terms of the landing gear forward velocity and loading force. For this a three-DoF model is used that does not include axial compression. This formulation along with suitable parameters allows for comparison with the existing literature, and an agreement is demonstrated with previous results for a zero side-stay angle. Subsequent variation of this angle is explored and a consistent picture presented, capturing the (transition of the two-parameter bifurcation diagram us a function of this angle. This shows a considerable increase in the complexity of the dynamics for intermediate side-stay angles. The appearance of an additional shimmy mode is observed and a region of tri-stability found where three distinct shimmy types coexist. For the study of freeplay the MLG model is extended to include axial compression; this axial DoF is required to accurately represent freeplay, introduced to the torque links of the system. Parameter values are chosen here to represent a typical mid-range civil aircraft MLG. The addition of freeplay is shown to result in shimmy oscillations that occur within the MLC operating envelope; their properties depend on both the size and 'shape' of freeplay. Freeplay and geometric coupling arc also considered together via consideration of a non-zero side-stay angle. Here, additional dynamic complexity is introduced in the presence of freeplay and, again , this coincidence with the appearance of a new shimmy mode. Further complex phenomena also appear, including multiple- frequency and chaotic-type oscillations, as well as complex transients. The non-zero geometry produce asymmetry and this results in a great sensitivity of the small-amplitude MLG behaviour to the exact shape of freeplay. Therefore, geometric orientation and freeplay a.re found to have significant effects and, when combined, they work together to produce additional complex phenomena, not otherwise observed when considered in isolation.

Under år 2008 uppskattades den totala produktionen av kugghjul inom bilindustrin till 2000 – 2500 miljoner detaljer, varav 1000 - 1400 miljoner av dessa är av hög kvalité [1]. För precisionskugghjul med modul under 1 mm kan tidsbegränsning och kostnader kopplade till design av skärverktyget elimineras genom att tillämpa en flexibel tillverkningsmetod som tillexempel abrasiv vattenskärning (AWJM). Denna studie undersöker designen av ett hybridtillverkningssystem konfigurerat kring AWJM samt föreslår finbearbetningsprocess via konventionella bearbetningsmetoder. Den tekniska möjligheten att producera kuggring av hög precision testas med en 5-axlig vattenjetmaskin och utvärderas enligt kvalitets nivåer för DIN-standard. För detta ändamål studerades ett kugghjul med modul 0,55 mm, 199 tänder, 110 mm i ytterdiameter och 72 mm i innerdiameter samt en tjocklek på 6 mm gjord av Armox T500, höghållfast stål. Resultaten visar på hög potential att uppnå ISO standardkvalité för kugghjul. Vissa kvalitetsegenskaper, definierade i DIN- och ISO-standarder, till exempel ytfinhet med låga värden; Ra 0,8 μm, uppnås vid användning av AWJM. Andra kvalitetskännetecken som profilavvikelse är relaterade till parametrar som skäreffekt, matningshastighet, mängd abrasivmedel, etc. Framtagna värden sträcker sig från Q10 och Q11 enligt DIN3967 vilket möjliggör slutoperationer som till exempel slipning. Geometrisk avvikelse, på ovansidan, gav en maximalt värde på 7 μm med en standardavvikelse på 4 μm. Jetstrålens eftersläpning observerades och kan kompenseras för medan resultatet av rundade hörn existerar i alla skärning med AWJ. Radiell förskjutning, tandtjocklek och index avvikelser visar värden som kan förbättras tillsammans med processoptimering, maskinkalibrering och eliminering av inneboende positionsavvikelser i maskinen. Varje enskild geometri kräver specifika processparametrar och CAM-programmens algoritmer behöver vidare optimeras för arbeten med tämligen små geometrier.
Production of gears for the automotive industry during 2008 is estimated to have been between 2000 – 2500 million pieces, from which 1000 to 1400 million pieces were high quality gears [1]. For precision gears with module below 1 mm, the time limitations and costs associated with the design of the cutting tool can be eliminated by using a flexible manufacturing technology such as Abrasive WaterJet Machining (AWJM). This project investigates the design of a hybrid manufacturing system configured by use of AWJM and proposed finishing processes using conventional machining methods. The technical feasibility is analysed to produce high precision ring gears using a 5-axes AWJM system to achieve DIN standards quality levels. For this purpose, a gear with a module of 0.55 mm, 199 teeth and 110 mm in the outer diameter and 130 teeth and 72 mm in the inner diameter with a thickness of 6 mm is studied; the selected material is Armox T500, a high strength steel. The results indicate high potential of producing ISO quality standard gears. Certain quality characteristics defined in DIN and ISO standards, for instance surface roughness – values as low as Ra 0.8 μm, are possible to achieve accurately by using AWJM. Others quality features as profile deviation, are related to parameters as cutting power, feed rate, abrasive feed rate, etc. The displayed values ranged Q10 and Q11 according to DIN3967 which allows for use of further finishing operations such as grinding. The top geometry deviations of a 0.3 mm cut, display a maximum value of 7 μm with an average value of 4 μm. Observed jet lag effects can be improved. Rounded corner effect exists in all AWJ cuts. Runout, tooth thickness and index deviations show values that can be improved together with process optimization, machine calibration and elimination of machine inherent positioning deviations. Each particular geometry needs specific process parameters and CAM software algorithms need further optimization for working with rather small design geometries.

The transformation of Joint forces to be lighter, more lethal, and capable of deploying from multiple dispersed locations free of prepared landing zones requires a dedicated heavy lift VTOL aircraft capable of rapidly delivering large payloads, such as the 20 to 26 ton Future Combat System, at extended ranges in demanding terrain and environmental conditions. Current estimates for a single main rotor configuration place the design weight over 130,000 pounds with an installed power of approximately 30,000 horsepower. Helicopter drive systems capable of delivering torque of this magnitude succeeded in the Russian Mi-26 helicopters split-torque design and the Boeing VERTOL Heavy Lift Helicopter (HLH) prototypes traditional multi-stage planetary design. The square-cube law and historical trends show that the transmission stage weight varies approximately as the two-thirds power of torque; hence, as the size and weight of the vehicle grows, the transmissions weight becomes an ever-increasing portion of total gross weight. At this scale, optimal gearbox configuration and component design holds great potential to save significant weight and reduce the required installed power. The drive system design methodology creates a set of integrated tools to estimate system weight and rapidly model the preliminary design of drives system components. Tools are provided for gearbox weight estimation and efficiency, gearing, shafting, and cooling. Within the same architecture, the designer may add similar tools to model subcomponents such as support bearings, gearbox housing, freewheeling units, and rotor brakes. Measuring the relationships between key design variables and system performance metrics reveals insight into the performance and behavior of a heavy lift drive system. A parametric study of select design variables is accomplished through an intelligent Design of Experiments that utilizes Response Surface Methodology to build a multivariate regression weight model. The model permits visualization of the design space and assists in optimization of the drive system preliminary design. This methodology is applied to both the Boeing HLH and the Russian Mi-26 main gearboxes. This study applies the drive system design methodology to compare the Mi-26 split-torque gearbox over the Boeing HLH multi-stage planetary gearbox in a single main rotor heavy lift helicopter.

Aerodynamic measurements were taken over models of the Boeing 777 high fidelity isolated landing gear in the 6- by 6-foot Virginia Tech Stability Wind Tunnel (VT-SWT) at a free-stream Mach number of 0.16. Noise control devices (NCD) were developed at Virginia Tech [9] to reduce noise by shielding gear components, reducing wake interactions and by streamlining the flow around certain landing gear components. Aerodynamic measurements were performed to understand the flow over the landing gear and also changes in the flow between "Baseline" and "NCD" configurations (without and with Noise Control Devices respectively). Hot-film, Pitot-static measurements and flow visualization using tufts were performed over an isolated 26% scale-model high fidelity landing gear for the "Baseline" and "NCD" configurations. Contours of turbulence intensity, normalized wake velocity and normalized total pressure loss for both configurations are compared. The "Baseline" configuration was also compared with the NASA Ames study conducted by Horne et al [7]. Hot-film measurements are also compared to Microphone Phased Array results which were acquired at Virginia Tech by Ravetta [8]. A novel technique for processing hot-film measurements by breaking turbulence into octave bands as acoustic measurements is presented. Particle Image Velocimetry (PIV) measurements were taken at six different locations over the 13% scale-model landing gear with no door and at a truck angle of zero degrees. Results are compared to PIV measurements taken over the wheels of a four-wheel landing gear by Lazos [10-12]. PIV results such as average velocity contours and vectors, streamlines and instantaneous velocity contours and vectors are presented. Results presented from PIV and flow visualization are in good agreement with results from Lazos [10-12].
Master of Science

The aim of this master thesis is modification of landing gear for accomplishment CS-23 regula-tion from that purpose, because landing gear in the use can't pass this type of certification. The first part examines the alternatives of landing gear with consideration optimal technical and eco-nomical difficulty. After finding optimal type of landing gear with shock absorber is there part of designing and computing the load. Last part of thesis is about stress analysis of whole con-cept and reconsidering final changes.

This study investigates the flow field and acoustics of a generic four wheel main landing gear. The landing gear is an important airframe noise source during the approach phase. The characteristics of the flow field around the bogie area of the main landing gear are largely unknown. CFD simulations using the DES turbulence model have been used to calculate the unsteady flow field around a generic landing gear model. The surface pressure data has been sampled and used in a FW-H solver to determine far field noise levels. Two different landing gear models have been used, a simplified geometry and a more realistic complex geometry. Three different bogie angles have been simulated: horizontal bogie aligned with the flow, 10⁰ toe up and 10⁰ toe down. Strong streamwise vortices are generated at the front wheels of the landing gear. The trajectory of these vortices determines where the turbulent flow interacts with the downstream components. This interaction leads to surface pressure fluctuations which are a major noise source. The flow field of the simplified configurations shows a consistent trend of the trajectory of the streamwise vortices with respect to changes in bogie angle. The far field noise levels generated by the different components of the simplified configurations are related to the distance at which the streamwise vortices pass. The additional components of the complex landing gear geometry change the characteristics of the flow field. The strong streamwise vortices persist but they do not show the same trend as for the simplified configurations. The wake of the articulation link generates a turbulent in flow for the other components. The different characteristics of the flow field of the complex configurations lead to significant changes in the far field noise levels of the components compared to the simplified configurations.

The goal of following master thesis is to design variety of configuration and retraction options of VUT200 TwinCobra landing gear. For each option are a wheel base and a gauge set up by possibility of main landing gear retraction. Next, CS 23 demands and stress analysis are followed. There is a view of twin engine aircraft landing gear disclosed as well.

In this thesis, we deal with the design of a shock absorber variant for the type of main landing gear design of the aircraft WT10 Advantic. Then we focus on the design of the selected variant of the main landing gear. Next, we follow regulation CS-23 demands to calculate the load cases for the selected main lending gear. Then we design shock absorber based on the load during landing. We compile the equation of motion of the aircraft, which describes motion of the aircraft during landing, then we compute the equation. Finally, we focus on a stress analysis of the main landing gear and the shock absorber.

This master thesis is about stress analysis of landing gear for accomplishment CS-23 regulation. The first part examines all alternatives of landing gear regarding for accomplishment of regulation. Next part is stress analysis of main and nose landing gear using FEM analysis in MSC Nastran software. Last part of master thesis describes topology optimization of two parts of landing gear.

This thesis studies the design of an electro-hydraulic landing gear and brakes control system of a trainer aeroplane. In the first part there is a basic draft of the landing gear kinematics and its loads during gear retraction, flight and landing. Braking conditions are also analysed. The thesis then focuses on the design of hydraulic circuits and their control. Simulations for studying the dynamic characteristics of the braking proportional valve and the course of plane braking were created in Simulink. There is also a brief section about reliability of the proposed system.

Hardening distortions are unwanted changes in shape and dimension that arise during hardening of steel components. Uncontrolled distortions induce random errors to the manufacturing process, and have a strong negative impact on manufacturing costs. The distortions are not only caused by the hardening process, several factors from previous manufacturing steps including the component geometry itself contribute to varying extent. The aim of the current work is to investigate the main influencing factors on hardening distortions for serial produced gears. The investigations were done on two different types of gears for heavy-duty transmissions, crown wheels for the rear axle central gear and main shaft gears for the gearbox. The steel was produced using either continuous casting or ingot casting. For rectangular continuously cast steel, the effect of disabling magnetic stirring of the steel melt during casting was investigated, finding a strong reduction of gear runout for crown wheels. Segregations in crown wheels produced from the top and bottom of ingots were shown to go in opposite directions, producing opposite back-face tilts. For crown wheels quenched one at a time, influences of stacking level on the hardening tray were found, indicating an impact from small variations in the carburizing process, despite identical quenching conditions. For main shaft gears, horizontal loading gave considerably less roundness and runout errors but increased flatness errors compared to vertical loading. This thesis shows the complexity of the distortion phenomenon and how several factors interact and contribute to the final result. It is shown that factors with significant impact on hardening distortions for one component may be less important for another component. With this in mind, each type of component to be hardened should be produced by a manufacturing chain where each process step is carefully chosen with respect to minimizing distortions.

QC 20170516

This master thesis deals with the landing gear rebuild from tail gear to nose gear of the M-4 Irbis aircraft. The first chapter presents the aircraft in its current state and includes some technical data, too. The theoretical information about types of landing gears, its characteristics, pros and cons and the typical representatives for each type of landing gear are mentioned in the second chapter. The third chapter is about landing gear loads that occur during landing and about the load calculation according to UL 2 regulation. The following chapter shows the construction of the new landing gear, including some of the suggested, but not realised, designs. In the fifth chapter, there is a landing gear strength calculation of some of the gear components. The calculation is analytical and then uses FEM. The very last chapter then shows the effect of new landing gear on the centre of gravity in its extreme positions. The chapter also compares aircraft masses with both landing gears.

Роботу виконано на кафедрі конструювання верстатів, інструментів та машин Тернопільського національного технічного університету імені Івана Пулюя Міністерства освіти і науки України Захист відбудеться 24 грудня 2019 р. о 11.00 годині на засіданні екзаменаційної комісії №10 у Тернопільському національному технічному університеті імені Івана Пулюя за адресою: 46001, м. Тернопіль, вул. Руська, 56, навчальний корпус №4, ауд. 101
У дипломній роботі проведено аналіз конструктивних особливостей базової моделі верстату, а також верстатів-аналогів. Здійснено аналіз загальних структур приводів головного руху вертикально-фрезерних верстатів. Проведено обґрунтування компонувальної схеми та технологічних параметрів для модернізації верстата. Здійснено розробку структури модернізованого приводу на основі морфологічної матриці. На основі проведено аналізу вибрано оптимальну компонувальну схему шпиндельного вузла та проведено дослідження впливу кількості підшипників в передній опорі на жорсткість шпиндельного вузла. Проведено кінематичний і силовий розрахунок ступеневої та безступеневої частин приводу, на основі яких розроблено конструкції коробки швидкостей, шпиндельного вузла, а також системи переключення між ступеневою і безступеневою частинами приводу головного руху вертикально-фрезерного верстату. Проведено розрахунок вартості модернізації приводу головного руху верстата. Розроблені технічні рішення обґрунтовано на основі вимог охорони праці, безпеки життєдіяльності та охорони навколишнього середовища.
Analysis of the structural features of the machine-tool basic model, as well as similar machine-tool, has been carried out in the diploma paper. Analysis of the general structures of the vertical-milling machine main feed drive was performed. The component scheme and technological parameters for the updating of the machine were interpreted. The structure of the improved drive basing on the morphological matrix was developed. The optimal compiling scheme of the spindle unit was chosen basing on it and investigation of the effect of the bearings number in the initial support on the spindle unit rigidity was performed. Kinematic and strength calculations of the speed drive and variable-speed drive part were done, basing on which the design of the gear-box, spindle unit and the system of gearing between speed drive and variable-speed drive of the main feed drive of the vertical-milling machine have been carried out. The calculation of the expenditures for the updating of the main feed of the machine-tool was done. The developed engineering solutions were interpreted to meet the requirements of the health and safety program and the program of the environment protection.
Вступ, Аналітичний розділ, Аналіз формоутворення, Обґрунтування компонувальної схеми верстату, Технологічний розділ, Науково-дослідний розділ, Конструкторський розділ, Спеціальний розділ, Охорона праці та БЖД, Екологія, Обґрунтування економічної ефективності, Висновки, перелік посилань

Orientadores: Jose Carlos Maldonado, Mario Jino
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação
Made available in DSpace on 2018-07-22T21:00:59Z (GMT). No. of bitstreams: 1 Vergilio_SilviaRegina_D.pdf: 8065952 bytes, checksum: 030c4242de7564d75e341340132d08f7 (MD5) Previous issue date: 1997
Resumo: Critérios de teste estrutural dividem o domínio de entrada de um programa em teste, em sub-domínios e requerem que pelo menos um ponto de cada sub-domínio seja executado, auxiliando na geração de dados de teste; permitem ainda, a avaliação da adequação de um dado conjunto de dados (casos) de teste. Uma vez particionado o domínio, é necessário responder à seguinte questão: "Que pontos de cada sub-domínio devem ser selecionados?". Isso diz respeito à tarefa de geração de dados de teste para satisfazer um critério. Essa é uma atividade bastante complexa de ser automatizada pois não existe um algoritmo de propósito geral para determinar um conjunto de casos de teste que satisfaça um dado critério para um particular programa. Não é possível nem mesmo determinar se esse conjunto existe. Na literatura são encontradas diferentes técnicas de geração de dados de teste que utilizam diferentes fundamentos para selecionar pontos do domínio que descrevem certos tipos de erros e, por isso, com alta probabilidade de revelar esses erros. No entanto, essas técnicas são apresentadas de forma dissociada dos critérios estruturais. Este trabalho introduz uma família de Critérios Baseados em Restrições, denominados Critérios Restritos, que têm o objetivo de aumentar a eficácia das atividades de teste e de oferecer medidas de cobertura. Os Critérios Restritos permitem a utilização de critérios estruturais juntamente com os princípios de técnicas de geração de dados de teste sensíveis a erros e foram motivados por resultados de estudos teóricos e empíricos conduzidos com essas técnicas. Nesse trabalho, esses resultados, que serviram como motivação para a introdução dos Critérios Restritos, são apresentados. São discutidos aspectos de complexidade e de relação de inclusão entre os Critérios Restritos e os demais critérios. Também é proposta uma extensão da ferramenta de testes POKE- TOOL para apoiar a utilização desses critérios e para facilitar a etapa de geração de dados de teste. Um experimento de avaliação dos Critérios Restritos é descrito. Os resultados desse experimento comprovam a aplicabilidade desses critérios e indicam um aumento no número de erros revelados. Ao final, são propostas duas estratégias de geração de dados de teste para satisfazer critérios de teste estrutural. Elas têm como objetivo reduzir os efeitos causados por caminhos não executáveis na atividade de teste e gerar dados com alta probabilidade de revelar erros. Entre essas estratégias propõe-se uma estratégia incremental, baseada na hierarquia entre os critérios, e que garante a preservação da relação de inclusão mesmo quando o fator eficácia é considerado
Abstract: Structural testing criteria divide the program input domain to sub-domains and require the execution of at least one point from each sub-domain. They support the test data generation phase and the adequacy analysis of a test set. Once the domain is divided, the question is posed: "What points in each sub-domain should be selected?" This question concerns to the task of generating test data to satisfy a criterion, which is very complex to be automated since there is no general algorithm to determine a set of test cases that satisfy a given criterion; it is not possible to determine even that such set exists. In the literature there are different test data generation techniques with different principIes for choosing points from the program domain associated to certain errors, with a high probability of revealing them. However these techniques are presented not associated to structural criteria. This work introduces a family of criteria, named Constraint Based Criteria. They have the goal of increasing the testing activity efficacy and make possible to obtain coverage measures. They permit the use of error-sensitive data generation techniques with structural criteria. The Constraint Based Criteria proposal was motivated by results obtained from empirical and theoretical studies with these techniques. These results are presented. Aspects of complexity and the inclusion relation among Constraint Based Criteria and othercriteria are discussed. An extension to POKE- TOOL is proposed with the goal of supporting Constraint Based Criteria and easing the data test generation phase. An experiment to evaluate the Constraint Based Criteria is described. The results from this experiment show their applicability and an increase in the number of revealed errors. And finally, two test data generation strategies to satisfy structural criteria are proposed. They have the goal of reducing the effects of infeasible paths in the testing activity and of generating test data with high probability of revealing errors. One of these strategies is incremental, based on the hierarchy of criteria and always preserve the inclusion relation among criteria even when the factor efficacy is considered.
Doutorado
Engenharia de Computação
Doutor em Engenharia Elétrica

Submitted by Setor de Tratamento da Informa??o - BC/PUCRS (tede2@pucrs.br) on 2015-04-17T14:25:56Z No. of bitstreams: 1 466589 - Texto Completo.pdf: 6603586 bytes, checksum: feeeb8bf10a13d97208972c59696bbb3 (MD5)
Made available in DSpace on 2015-04-17T14:25:56Z (GMT). No. of bitstreams: 1 466589 - Texto Completo.pdf: 6603586 bytes, checksum: feeeb8bf10a13d97208972c59696bbb3 (MD5) Previous issue date: 2014-04-23
Conselho Nacional de Pesquisa e Desenvolvimento Cient?fico e Tecnol?gico - CNPq
The images, which correspond to slices in MRIs are part of the protocols used to aid in the diagnosis of multiple sclerosis and have lesions that characterize the disease. Among existing protocols, are the routine protocol and protocol specific for the disease being evaluated. The MRI scan of the specific protocol is an expensive and time-consuming test, but presents a more accurate quantification of volumetric lesion in the brain. The MRI scan of the routine protocol is an inexpensive routine examination; however, its accuracy is lower for quantifying the volume of multiple sclerosis lesions, due to the fact that it has a lower amount of data. Within this context, this dissertation presents the application of interpolation methods to generate artificial images through the images on the MRI scan of the routine protocol in order to simulate the images of the specific protocol for multiple sclerosis. At the end, an approach is presented that aims to improve the precision obtained with the interpolation techniques used to increase the reliability of volumetric lesion generated by interpolations.
As imagens, que correspondem ? cortes em exames de resson?ncia magn?tica, fazem parte dos protocolos utilizados para o aux?lio no diagn?stico da esclerose m?ltipla e apresentam as les?es que caracterizam a doen?a. Dentre os protocolos existentes, est?o o protocolo de rotina e o protocolo espec?fico para a doen?a que est? sendo avaliada. O exame de resson?ncia magn?tica do protocolo espec?fico ? um exame caro e demorado, por?m apresenta uma quantifica??o mais precisa da volumetria das les?es no c?rebro. O exame de resson?ncia magn?tica do protocolo de rotina ? um exame barato, entretanto, sua precis?o ? menor para a quantifica??o do volume de les?es de esclerose m?ltipla, devido ao fato de possuir uma quantidade inferior de dados. Dentro desse contexto, o presente trabalho apresenta a aplica??o de m?todos de interpola??o para gerar imagens artificiais, atrav?s das imagens presentes no exame de resson?ncia magn?tica do protocolo de rotina com o objetivo de simular as imagens contidas no exame do protocolo espec?fico para a esclerose m?ltipla. Ao final, ? apresentada uma abordagem que visa melhorar a precis?o obtida com as t?cnicas de interpola??o utilizadas, visando aumentar a confiabilidade da volumetria de les?es geradas pelas interpola??es.

Bien qu’ils soient largement utilisés dans le domaine, les mesures vibratoires classiques présentent plusieurs limites. A la base, l’analyse vibratoire ne peut identifier qu’environ 60% des défauts qui peuvent survenir dans les machines. Cependant, les principaux inconvénients des mesures de la vibration sont l’accès difficile au système de transmission afin d’y placer le capteur ainsi que le coût conséquent de la mise en œuvre. Ceci résulte en des problèmes de sensibilité relatifs à la position de l’installation et ceux de difficulté pour distinguer la source de vibration à cause de la diversité des excitations mécaniques qui existent dans l’environnement industriel.Par conséquent, l’analyse des signatures du courant électrique des moteurs s’impose comme une alternative prometteuse à l’analyse vibratoire et a donc fait l’objet d’une attention grandissante au cours des dernières années. En effet, l’analyse des signatures électriques a l’avantage d’être une méthode techniquement accessible, non-intrusive au système et peu coûteuse. Les techniques basées sur le courant et la tension ne requièrent que les mesures électriques du moteur qui sont souvent déjà surveillées pour le contrôle et la protection des machines électriques. Ce processus a été principalement utilisé pour la détection des défauts de moteur tels que la rupture de barres du rotor et les défauts d’excentricité ainsi que les défauts de roulements. En revanche, très peu de recherches concernent la détection des défauts en utilisant l’analyse du courant. En outre, les signaux électriques triphasés sont caractérisés par des représentations géométriques particulières liées à leur forme d’onde qui peuvent servir en tant qu’indicateurs différents offrant des informations supplémentaires. Parmi ces indicateurs géométriques, les transformées de Park et de Concordia modélisent les composantes électriques dans un repère bidimensionnel et toute déviation par rapport à la représentation d’origine indique l’apparition d’un dysfonctionnement. Aussi, les équations différentielles de Frenet-Serret représentent la trajectoire du signal dans un espace euclidien tridimensionnel et indiquent ainsi tout changement dans l’état du système. Bien qu’ils aient été utilisés pour les défauts de roulements, ces indicateurs n’ont pas été appliqués dans la détection des défauts d’engrenages en utilisant l’analyse des signatures des courants électriques. D’où l’idée novatrice de combiner ces indicateurs avec des techniques de traitement de signal, ainsi que des techniques de classification pour le diagnostic des engrenages en utilisant l’analyse des signatures de courant et de tension du moteur électrique.Ainsi, dans ce travail, on propose une nouvelle approche pour le diagnostic des défauts d’engrenages en utilisant l’analyse des courants et des tensions électriques du stator de la machine et ceci en se basant sur un ensemble d’indicateurs géométriques (Transformées de Park et de Concordia ainsi que les propriétés du repère Frenet-Serret). Ces indicateurs font partie d’une bibliothèque de signatures de défauts qui a été construite et qui comprend également les indicateurs classiques utilisés pour un large éventail de défauts. Ainsi, un algorithme combine les acquisitions expérimentales des signaux électriques à des méthodes de traitement de signal avancées (décomposition modale empirique,…). Ensuite, celui-ci sélectionne les indicateurs les plus pertinents au sein de la bibliothèque en se basant sur les algorithmes de sélection de paramètres (sélection séquentielle rétrograde et analyse des composantes principales). Enfin, cette sélection est utilisée pour la classification non-supervisée (K-moyennes) pour la distinction entre l’état sain et l’état défaillant
Although they are widely used, classical vibration measurements have several limitations. Vibration analysis can only identify about 60% of the defects that may occur in mechanical systems. However, the main drawbacks of vibration measurements are the difficult access to the transmission system in order to place the sensor as well as the consequent cost of implementation. This results in sensitivity problems relative to the position of the installation and the difficulty to distinguish the source of vibration because of the diversity of mechanical excitations that exist in the industrial environment.Hence, the Motor Current Signatures Analysis (M.C.S.A.) represents a promising alternative to the vibration analysis and has therefore been the subject of increasing attention in recent years. Indeed, the analysis of electrical signatures has the advantage of being a technically accessible method as well as inexpensive and non-intrusive to the system. Techniques based on currents and voltages only require the motor’s electrical measurements which are often already supervised for the purposes of the control and the protection of the electrical machines. This process was mainly used for the detection of motors faults such as rotor bars breakage and eccentricity faults as well as bearings defects. On the other hand, very little research has been focused on gear faults detection using the current analysis. In addition, three-phase electrical signals are characterized by specific geometric representations related to their waveforms and they can serve as different indicators providing additional information. Among these geometric indicators, the Park and Concordia transforms model the electrical components in a two-dimensional coordinate system and any deviation from the original representation indicates the apparition of a malfunction. Moreover, the differential equations of Frenet-Serret represent the trajectory of the signal in a three-dimensional euclidean space and thus indicate any changes in the state of the system. Although they have been previously used for bearing defects, these indicators have not been applied in the detection of gear defects using the analysis of electrical current signatures. Hence, the innovative idea of combining these indicators with signal processing techniques, as well as classification techniques for gears diagnosis using the three-phase motor’s electrical current signatures analysis is established.Hence, in this work, a new approach is proposed for gear faults diagnosis using the motor currents analysis, based on a set of geometric indicators (Park and Concordia transforms as well as the properties of the Frenet-Serret frame). These indicators are part of a specifically built fault signatures library and which also includes the classical indicators used for a wide range of faults. Thus, a proposed estimation algorithm combines experimental measurements of electrical signals with advanced signal processing methods (Empirical Mode Decomposition, ...). Next, it selects the most relevant indicators within the library based on feature selection algorithms (Sequential Backward Selection and Principal Component Analysis). Finally, this selection is combined with non-supervised classification (K-means) for the distinction between the healthy state and faulty states. It was finally validated with a an additional experimental configuration in different cases with gear faults, bearing faults and combined faults with various load levels

碩士
淡江大學
航空太空工程學系碩士班
98
The application of composite material on the aerospace industry begin WWII, the percentage from not more than 1% to the newly aircraft Boeing 787 nearly 50% of aircraft structure using the composite material. Recently, cause of the fuel price increased, the aircraft manufacture to search for the new method decrease the aircraft fuel consumption. Using composite material is the method one of the method to solve the question. Decrease the fuel consumption is mean that the airliner can carry more passengers and more cargos, make the airliner cut down the expenses of fuel consumption. Thus, the using composite material is an important of future aerospace industry. This research is focus on the light sport aircraft main landing gear structural analysis, by change the material from using the 6061-T6 aluminum to the S-Glass fiber composite material. Using finite element method to analysis the difference material of the main landing gear on the static and dynamic condition. And study the relative aviation composite regulations and light sport aircraft regulations, some of the boundary condition is connect with these regulations, for intense, the payload is use the light sport aircraft regulations. Verify the reliable of the dynamic simulation observe the change between dynamic energy and internal energy, hourglass energy and sliding energy. Then increase the glide slope angle for 3°and 5°, observe the difference between aluminum and composite material main landing gear stress, strain and energy change, the static result shows that composite material stress decrease 5%, strain decease 30%, weight decrease 8%, and establish the reliable simulation platform. Provide the data for light sport aircraft design and analysis.

The Mi-24 helicopter is one of the most famous heavy lift helicopters designed with a net weight of 8.4 tonnes, while its gross weight is 12.5 tonnes. This helicopter is powered by two TV3-117 turbo-engines, coupled to a VR-24 main rotor transmission gearbox, which reduces the engine speed from 15000 Revolutions Per Minute (RPM) to the main rotor speed of 240 RPM. This research aims to show the functionality of the Mi-24 helicopter main gear box, to find the opportunities to extend the running hours (before maintenance) and to refurbish the gear box locally in South Africa. The research follows the principles of Reverse Engineering (RE) and Refurbishing. The principles involve the extraction of information from an existing product in order to establish its function and to re-create specifications which can be used to make, maintain or refurbish a similar or superior item. This dissertation has exposed some of the theory of the design of the Mi-24 main gearbox components and their functionality; including similar selected helicopters’ main drive mechanisms. The probable defects that are common to helicopter transmissions, the specifications and the Computer Aided Design (CAD) drawings are also presented. The research concludes that, with the cooperation of the local aerospace industry (including the army), the academic institutions and government; it is possible to get the necessary certification, licensing, training, specialised equipment and to establish a Maintenance Organisation, to refurbish the Mi-24 helicopter gearbox locally in South Africa.

碩士
國立成功大學
航空太空工程學系碩士在職專班
107
The purpose of this thesis is to research and investigate main landing gear door malfunctions that frequently occur in T-34C aircraft. Aircraft airflow changes continuously in the air. In order to find the reason for landing gear malfunctions, I proposed a hypothesis with fixed characters and values in a real situation. I collected the frequency of discrepancies in T-34C aircraft in 2014. According to the technical order and operating principles of the T-34C landing gear system, I posited that there is a pressure difference between the inside and outside of the landing gear cabin when the aircraft are in the air. I calculated the force of the T-34C airfoil (NACA23016) in CFDRC when aircraft fly at 90, 100, 110, 120 knots per hour at an altitude of 10,000 ft. The results of experiments indicate the following: 1.Technicians need to adjust the landing gear tension (54-67 pounds). 2. The pilot should put the landing gear up when flying at speeds over 100 knots per hour.

Thesis (M.S.)--University of Tennessee, Knoxville, 2004.
Title from title page screen (viewed Sep. 20, 2004). Thesis advisor: George W. Garrison. Document formatted into pages (x, 89 p. : ill. (some col.)). Vita. Includes bibliographical references (p. 39-40).

В дипломній роботі виконано модернізації дільниці ремонтного цеху для ремонту головної передачі та задньої підвіски автомобіля ГАЗ-3302.
In the thesis the modernization of the section of the repair shop was performed to repair the main transmission and rear suspension of the GAZ-3302.
Вступ 1 Загально-технічний розділ 2 Технологічний розділ 3. Конструкторський розділ 4 Спеціальний розділ 5 Науково-дослідний розділ 6 Проектний розділ 7 Обгрунтування економічної ефективності 8 Охорона праці та безпека в надзвичайних ситуаціях 9 Екологія Загальні висновки щодо магістерської роботи Бібліографія Додатки

A sociedade em que vivemos, procura cada vez mais, conhecer e compreender indivíduos que tenham atingido o sucesso, nas diferentes áreas de actuação. Neste âmbito, os meios de comunicação tentam oferecer a informação que o público quer consumir, tornando, high-achievers, em exemplos a seguir. Esta exploração da imagem de pessoas bem sucedidas pode ser prejudicial na forma como eles próprios encaram e visualizam aquilo que conquistaram, ou seja o seu próprio sucesso. Esta dissertação tem como objectivo perceber e analisar de que maneira se pode gerir o sucesso depois do mesmo ter sido alcançado, de forma a que se continue no topo. Para esta investigação recolhemos informação através de leituras sobre José Mourinho e André Villas-Boas para além de termos entrevistado cinco profissionais bem sucedidos em diversas áreas da sociedade, quatro deles na área do desporto e o restante no âmbito empresarial. Entre as conclusões que apresentamos, destacamos a de que um high-achiever deve encarar, dia a dia como um novo desafio. A auto-liderança, como conceito, guiou-nos no entendimento de como o sucesso pode ser gerido de forma a adicionar mais sucesso ao que já foi atingido.
Nowadays the society we live in looks at learning, understanding and getting to know better those that have achieved great success in their careers, in whichever subject matter. Hence, the media has dedicates much of its time to make available information that the audience eagerly wants, therefore turning therefore the highachievers into society role models. This continuous attention to the person rather than his/her achievements can be detrimental to how he/she conducts his/hers life and how looks back on his/her achievements, or rather his/her own success. This dissertation aims to understand and analyse in which ways the success can be managed in order to keep on growing rather than being negatively affected by it. This considers readings about José Mourinho and André Villas-Boas as well as information from five conducted interviews, four of these in the sports industry and the one in an entrepreneurial light. Among our conclusions it is the notion that a high-achiever must face a new challenge on a daily basis. The self-conduct/self-leadership, as a concept, lead us to understand how success can be managed in a way of adding more value to what has already been achieved.