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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Aircraft engine performance and integration in a flying wing aircraft conceptual design

Miao, Zhisong. 01 1900 (has links)
The increasing demand of more economical and environmentally friendly aero engines leads to the proposal of a new concept – geared turbofan. In this thesis, the characteristics of this kind of engine and relevant considerations of integration on a flying wing aircraft were studied. The studies can be divided into four levels: GTF-11 engine modelling and performance simulation; aircraft performance calculation; nacelle design and aerodynamic performance evaluation; preliminary engine installation. Firstly, a geared concept engine model was constructed using TURBOMATCH software. Based on parametric analysis and SFC target, the main cycle parameters were selected. Then, the maximum take-off thrust was verified and corrected from 195.56kN to 212kN to meet the requirements of take-off field length and second segment climb. Besides, the engine performance at offdesign points was simulated for aircraft performance calculation. Secondly, an aircraft performance model was developed and the performance of FW-11 was calculated on the basis of GTF-11 simulation results. Then, the effect of GTF-11 characteristics performance on aircraft performance was evaluated. A comparison between GTF-11 and conventional turbofan, RB211- 524B4, indicated that the aircraft can achieve a 13.1% improvement in fuel efficiency by using the new concept engine. Thirdly, a nacelle was designed for GTF-11 based on NACA 1-series and empirical methods while the nacelle dimensions of conventional turbofan RB211-525B4 were obtained by measure approach. Then, the installation thrust losses caused by nacelle drags of the two engines were evaluated using ESDU 81024a. The results showed that the nacelle drags account for about 4.08% and 3.09% of net thrust for GTF-11 and RB211-525B4, respectively. Finally, the considerations of engine installation on a flying wing aircraft were discussed and a preliminary disposition of GTF-11 on FW-11 was presented.
2

On The Synthesis Of A Class Of Geared Linkage Mechanisms

Parlaktas, Volkan 01 May 2007 (has links) (PDF)
In this thesis, two types of geared linkages are studied in detail. One of the mechanisms is the geared five link mechanism for which the input and output shafts are collinear. The other is a two degree-of-freedom nine-link mechanism which is called the &quot / geared adjustable stroke mechanism&quot / . The geared adjustable stroke mechanism uses the geared five link mechanism in its structure. The geared adjustable stroke mechanism has been used in practice, but neither of these mechanisms have been studied in the literature. Analysis procedures are developed and expressions for the transmission angles of the mechanisms are derived. A synthesis procedure is proposed and charts are prepared for the design of such mechanisms.
3

Design and performance evaluation of an outer stator magnetically geared permanent magnet machine

Tlali, Pushman Micheal 03 1900 (has links)
Thesis (MEng)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Please refer to full text for abstract.
4

The Influence of a Class of Surface Defects on the High-Speed Scuffing Performance of Spur Gears

Beall, Gunther Shepard January 2021 (has links)
No description available.
5

A QUALITATIVE ANALYSIS OF SOCIAL HOUSING RESIDENTS

Beck, Andrew E. 10 1900 (has links)
<p>The social determinants of health are the social and economic conditions in which people live that determine their health and housing is a determinant of health. The home holds important significance to individuals as it offers protection and privacy from the surrounding physical and social conditions, aids in the development of relationships, and is the centre of family life. However, many individuals are not able to experience the benefits stemming from an acceptable home.</p> <p>This thesis explores the socio-economic aspects of housing through the transitional experiences of individuals moving from the private market level housing into rent-geared-to-income housing. The aim was to offer a descriptive account of individuals who have moved into social housing from private market housing and to find which of the dimensions of housing (physical conditions, psychological benefits, social environment and financial dimensions) most definitely contribute to individuals' everyday lives, health and well-being.</p> <p>Through the use of in-depth interviews, this cross-sectional research study involves 12 individuals paying rent-geared-to-income and living in social housing in Hamilton, Burlington and Oakville, Canada.</p> <p>Individuals reported several improvements to the different dimensions of housing that can influence health. Better housing conditions did improve their general and mental health. Individuals reported a greater sense of security, autonomy and self-identity. Social interactions and support were more commonly experienced and individuals did feel a decrease in the burden of rent. The most substantial changes were living in a less stressful environment and the financial security of social housing.</p> <p>This thesis shows that securing social housing had an influence on participants' everyday lives, health and well-being. The findings may contribute to literature on the impacts of affordable housing on lower-income individuals’ health and well-being. Additionally, the findings have important housing policy implications for addressing affordable housing.</p> / Master of Arts (MA)
6

Da terra das sombras à terra dos sonhos. O espaço sagrado na literatura para crianças e jovens / From the shadow land to the dream land: the sacred space in the literature geared at children and young people

Lopes, Cristiano Camilo 03 June 2009 (has links)
Esta dissertação tem como objetivo identificar a presença do espaço sagrado na Literatura para Crianças e Jovens. Para isso, utilizamos como eixo teóricometodológico propostas sociológicas e antropológicas sobre o sagrado e sua relação com o homem. Como um substrato para mitos, ritos e arquétipos, o sagrado tem permeado a Literatura para Crianças e Jovens, revelando o homem e sua relação com suas crenças. Em diversas obras, evidencia-se como um elemento essencial e norteador do ser que o aceita. Assim, recorrendo ao estudo de temas (tematologia) como método comparativista, objetivamos identificar a configuração do espaço sagrado, pela oralidade, em duas obras: A menina de lá, de Guimarães Rosa, e O beijo da palavrinha, de Mia Couto. Além disso, pelo mesmo método comparativista, analisaremos as obras As Crônicas de Nárnia: o leão, a feiticeira e o guarda-roupa, de C. S. Lewis e Cibermãe, de Alexandre Jardin, com o objetivo de identificar o retorno do sagrado nos dias atuais e, verificar que o sagrado não se limita a épocas, mas até mesmo na modernidade o homem o busca. / This essay aims at identifying the presence of the sacred space in the literature geared at children and young people. For this we used the theoretical - methodological axis as the sociological and anthropological proposals on other sacred and its relationship with man. As a basis for myths, rites and models, the sacred has permeated literature for children and young people, revealing man and his relation to his beliefs. In several literary works, the sacred is highlighted as an essential element and a guide for the man who accepts it. Likewise, resorting to the study of themes as a comparative method, we aim to identify the sacred space by oral sources in two works: A menina de lá, by Guimarães Rosa and O beijo da palavrinha by Mia Couto. According to the same comparative method, we will analyze the following works: The chronicles of Narnia: the lion, the witch and the wardrobe by C.S. Lewis and Cybermother by Alexander Jardin, aiming in both cases to identify the return of the sacred to the present day, observing that the sacred does not limit itself to periods, but man searches for it even in modern days.
7

Da terra das sombras à terra dos sonhos. O espaço sagrado na literatura para crianças e jovens / From the shadow land to the dream land: the sacred space in the literature geared at children and young people

Cristiano Camilo Lopes 03 June 2009 (has links)
Esta dissertação tem como objetivo identificar a presença do espaço sagrado na Literatura para Crianças e Jovens. Para isso, utilizamos como eixo teóricometodológico propostas sociológicas e antropológicas sobre o sagrado e sua relação com o homem. Como um substrato para mitos, ritos e arquétipos, o sagrado tem permeado a Literatura para Crianças e Jovens, revelando o homem e sua relação com suas crenças. Em diversas obras, evidencia-se como um elemento essencial e norteador do ser que o aceita. Assim, recorrendo ao estudo de temas (tematologia) como método comparativista, objetivamos identificar a configuração do espaço sagrado, pela oralidade, em duas obras: A menina de lá, de Guimarães Rosa, e O beijo da palavrinha, de Mia Couto. Além disso, pelo mesmo método comparativista, analisaremos as obras As Crônicas de Nárnia: o leão, a feiticeira e o guarda-roupa, de C. S. Lewis e Cibermãe, de Alexandre Jardin, com o objetivo de identificar o retorno do sagrado nos dias atuais e, verificar que o sagrado não se limita a épocas, mas até mesmo na modernidade o homem o busca. / This essay aims at identifying the presence of the sacred space in the literature geared at children and young people. For this we used the theoretical - methodological axis as the sociological and anthropological proposals on other sacred and its relationship with man. As a basis for myths, rites and models, the sacred has permeated literature for children and young people, revealing man and his relation to his beliefs. In several literary works, the sacred is highlighted as an essential element and a guide for the man who accepts it. Likewise, resorting to the study of themes as a comparative method, we aim to identify the sacred space by oral sources in two works: A menina de lá, by Guimarães Rosa and O beijo da palavrinha by Mia Couto. According to the same comparative method, we will analyze the following works: The chronicles of Narnia: the lion, the witch and the wardrobe by C.S. Lewis and Cybermother by Alexander Jardin, aiming in both cases to identify the return of the sacred to the present day, observing that the sacred does not limit itself to periods, but man searches for it even in modern days.
8

Simulation de l'usure et d'avaries sur des dentures d'engrenages cylindriques : Influence sur le comportement statique et dynamique de transmission par engrenages / Simulation of wear and damages on the teeth of cylindrical gears : Influence on static and dynamic behaviour of geared transmissions

Osman, Thaer 02 February 2012 (has links)
Les systèmes de transmission par engrenages sont largement utilisés pour transmettre de la puissance et adapter les vitesses de rotation entre organes moteurs et récepteurs. Dans ce contexte, les engrenages sont fréquemment les organes parmi les plus sensibles de la chaîne cinématique et peuvent être soumis à un grand nombre d’avaries (fatigue de contact, fatigue de flexion, usure…etc.) apparaissant lors du fonctionnement et dont les causes sont multiples. L’objectif de ce travail est, d’une part, de simuler l’usure abrasive et la fatigue de contact conduisant à de l’écaillage (pitting) et, d’autre part, d’analyser les interactions entre ces avaries et le comportement statique et dynamique de transmission par engrenages. A cette fin, un modèle dynamique tridimensionnel d’engrenages de fortes largeurs est couplé à des modèles d’usure et d’avaries de contact. L’usure est simulée en s’appuyant sur le modèle d’Archard modifié afin de tenir compte de l’influence du régime de lubrification. Les usures obtenues après un certain nombre de cycles de chargement sont considérées comme des écarts initiaux additionnels par rapport à la géométrie idéale du flanc de denture. Les phénomènes de fatigue de contact par pitting sont analysés en deux étapes; a) une période d’initiation de fissure simulée en s’appuyant sur plusieurs critères de fatigue multiaxiaux et b) une phase de propagation de fissure traitée par la mécanique linéaire élastique de la rupture. Les sollicitations dynamiques fournies par le modèle dynamique d’engrenages sont utilisées comme données d’entrée pour la simulation des périodes d’initiation puis de propagation. Un grand nombre d’exemples d’application sont présentés et les interactions entre comportement dynamique, usure et fatigue sur des engrenages cylindriques sont analysées. / Gear transmissions have high power-to-weight ratios, can be made very compact and match the speeds and torques of one machine to another with high efficiency. However, gears are one of the weakest links in a transmission and can develop a number of failures (wear, contact fatigue, bending fatigue, etc.) which downgrade the overall transmission performance. The objective of this work is twofold; on the one hand, simulate abrasive wear on tooth flanks and contact fatigue leading to pitting, on the other hand, analyse the interactions between these damages and the dynamic and static behaviour of geared transmissions. To this end, a three dimensional gear dynamic model is used and coupled with several wear and fatigue models. The wear on tooth flanks is simulated based on a modified Archard’s law which includes the influence of the lubrication regime. Wear is accounted for via time- and position-varying distributions of normal deviations with respect to ideal flank geometry which are superimposed on profile and lead modifications. The occurrence of pitting is divided into two periods: a) a crack initiation period simulated by using several multi-axial fatigue criteria and, b) a crack propagation phase which is tackled using the theory of linear elastic rupture mechanics. The dynamic tooth loads delivered by the gear dynamic model are used as input data for the simulations of crack initiation and then crack propagation. A number of results are presented and the interactions between wear, contact fatigue and dynamic behaviour are investigated and commented upon.
9

Rational Reform of Housing Access Policy in Ontario

Ries, Benjamin Carter 19 December 2011 (has links)
Ontario’s current regulatory approach to low-income housing lies between two primary challenges: the human right to housing, and political/fiscal constraints. This thesis draws on legal theory and economic analysis of law to articulate the proper goals of housing access policy. A structural theory is proposed to explain the normative relationship between efficiency, communitarianism and justice in housing. An array of regulatory options are compared and considered in light of the features that characterize Ontario’s low-income rental housing markets. This analysis favours demand-side housing subsidies to low-income households, combined with supply-side tax expenditures to improve elasticity in the low-income rental market. Further reform of rent and covenant controls, social and affordable housing supply, and land use planning is recommended to ensure an efficient residential tenancy market. These reforms are offered as a framework for the implementation of the human right to housing in Ontario.
10

Rational Reform of Housing Access Policy in Ontario

Ries, Benjamin Carter 19 December 2011 (has links)
Ontario’s current regulatory approach to low-income housing lies between two primary challenges: the human right to housing, and political/fiscal constraints. This thesis draws on legal theory and economic analysis of law to articulate the proper goals of housing access policy. A structural theory is proposed to explain the normative relationship between efficiency, communitarianism and justice in housing. An array of regulatory options are compared and considered in light of the features that characterize Ontario’s low-income rental housing markets. This analysis favours demand-side housing subsidies to low-income households, combined with supply-side tax expenditures to improve elasticity in the low-income rental market. Further reform of rent and covenant controls, social and affordable housing supply, and land use planning is recommended to ensure an efficient residential tenancy market. These reforms are offered as a framework for the implementation of the human right to housing in Ontario.

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