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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

Generation of 3D autostereoscopic integral images using computer simulated imaging systems

Salih, Shafik January 2015 (has links)
Production of artificial Three-Dimension (3-D) images was the aim of many researches over hundreds of years. 3-D images are the images that create sense of depth when viewing them. 3-D images are closer to the real world scenes than 2-D images due to the 3-D effect or the sense of depth the 3-D images provide. Sense of depth can be caused by binocular cues including convergence and parallax. Convergence is created by the difference between the angles of the left eye and the right eye viewing axes. Parallax is the effect of viewing with one eye a view of the scene that is inherently shifted to the view seen by the other eye. Several techniques have targeted the creation of 3-D images with the mentioned cues. The technique is preferred when it is able to create 3-D images so that the viewer can view these images without wearing special glasses and the occurrence of viewer fatigue. Integral photography that was invented in 1908 is able to meet the previous requirements. Based on integral photography, several techniques, research and studies have been published. The purposes of this thesis include the computer simulation of flexible integral photography systems, the computer generation of good quality 3-D static and animated integral images using the simulated systems, optimising the generation process to be more accurate, less expensive, more effective, and faster, and producing a portable specialist software tool to achieve these targets. New techniques and algorithms are needed to meet these purposes. A literature survey was carried out about the closest researches and studies to the subject of computer-generated integral images; these were compared with the new techniques introduced in this study to prove the advantages and the necessity of these new techniques. The closest technique to the suggested techniques was implemented using more developed tools to compare the quality of the resulting integral images with the targeted integral images that are going to be produced using the tools and algorithms proposed in this thesis. A method to simulate an imaging system and produce integral images based on the new technique of dividing the view volume of the scene was introduced, explained, proved, and implemented with a program designed for this purpose. To optimise the processing time and the image quality, the previous method is developed, new features are added to the resulting integral images, and better performance was achieved by introducing the method of Displacing the Virtual Camera Target (DCT). Application software with Graphical User Interface is designed and implemented to allow users to select the required parameters of the imaging system and the required features of the resultant integral images. The software tool that is based on the developed techniques and employing OpenGL is useful to simulate the imaging systems, tune their parameters before the actual implementation of these systems, and as a result, save time and materials when designing these systems. The introduced techniques and the software tools are faster, more effective, and cheaper original methods to help in optimising both the integral imaging systems and the quality of integral images. These software tools based on the new techniques can be used on a wide range of devices and platforms because these are employing the portable Application Interface OpenGL. With these methods, integral imaging systems are simulated, and optimised; good quality static and animated integral images were created.
2

The effects of water displacing corrosion preventatives on the fatigue behaviour of mechanically fastened aluminium joints

Dhamari, Ruby Dharma Adji, Aerospace, Civil & Mechanical Engineering, Australian Defence Force Academy, UNSW January 2005 (has links)
Two failure mechanisms in a double lap joint are investigated. Analytical models of net-section and gross-section failure modes are proposed to describe these mechanisms. The effects of lamping force, interference fit, maximum axial load and WDCP on fatigue performance of the joint are included in the models. The effect of WDCP is assumed to give a reduction in friction coefficient. Three types of stress reduction factors are proposed in the net-section failure model to account for these parameters. The stress reduction factors modify stress range that is used in crack growth calculation. If there are no effects of these parameters, the stress reduction factors are equal to one. Two types of fretting stress are introduced in gross-section failure model to describe either sliding contact or incipient sliding contact on faying surface. The fretting stress is combined with body stress to modify stress range. The net-section failure model predicts that fatigue life is increasing as interference fit, clamping force and friction coefficient increase. The gross-section failure model predicts that fatigue life is decreasing as clamping force and friction coefficient increase. Both models predict that fatigue life is decreasing as maximum axial load increases. Transition of the failure mode occurs earlier as friction coefficient and interference fit increase, while it is delayed as maximum axial load increases. A transition parameter is proposed to establish a relationship between the four main parameters. The transition parameter is expressed in a polynomial equation. It gives an optimum combination of the four main parameters in order to achieve relatively higher fatigue life by having gross-section failure mode. Finite element analysis and fatigue testing are performed to validate the models. The finite element and the analytical models show that stress concentration factor at the edge of the hole is decreasing as clamping force increases. The rate of decrease of stress concentration factor is increasing as friction coefficient increases. While stress concentration factor on the faying surface is increasing as clamping force and friction coefficient increase. Fatigue testing reveals that the fatigue life of the joint is in good agreement with the predicted fatigue life of the proposed models.
3

Konkurenční strategie firmy, vyloučení konkurence / Competitive strategy: Displacing the competition

Hasanbayova, Sabina January 2017 (has links)
The diploma thesis focuses on current and future competitive strategy of the chosen enterprise and recommends improvements of this strategy. It specifies main focus of the management in the next five years and suggests effective methods needed to improve competitive strategy of this company.

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