Thesis (Ph. D.)--Ohio State University, 1980. / Includes bibliographical references (leaves 185-190). Available online via OhioLINK's ETD Center.

Thesis (Ph. D. in Civil and Environmental Engineering)--University of California, Berkeley, 2007. / "Spring 2007." Includes bibliographical references (p. 173-179). Also available online via the ITS Berkeley web site (www.its.berkeley.edu).

Thesis (M.S.)--Naval Postgraduate School, 2006. / "December 2006." Includes bibliographical references (p.41-42). Also available online from the Web site of the Naval Postgraduate School (http://www.nps.edu).

Thesis (M.S.)--Naval Postgraduate School, 2006. / "December 2006." Includes bibliographical references (p. 137-141). Also available online from the Web site of the Naval Postgraduate School (http://www.nps.edu).

Division of Policy Research and Analysis, National Science Foundation under Grant no. OEP 76-00284

Refineries, the chemical industry, airports etc. have an existing stock of thousands of storage tanks, the majority of which were manufactured in the sixties. Depending on the field of industry they are used in, these tanks contain environmentally harmful fluids such as gasoline or petroleum oil in the petrochemical industry or acids in the chemical industry. Other than in newly constructed tanks, there are few possibilities in preventive leak detection in older tank constructions, as the bottom plate is in direct contact to the ground. Hidden corrosion in this structural element has caused a series of catastrophic petroleum spills in the past. In response to these spills, guidelines which specify how and when to inspect tanks have been established globally to guarantee their structural integrity. To allow the inspection of the tank's bottom plate in particular, using state of the art techniques and equipment, the tanks are taken out of service and prepared for the inspection. This preparation process requires draining, washing, degassing and ventilating the tank which is a very polluting, time consuming and expensive process. A review of existing approaches has shown that automated inspection systems where a crawler carries the inspection probes, while the tank remains filled, can circumvent the need for the preparation process. However, there are some serious limitations to such systems as the crawlers used are in direct contact with the tank's structure, where obstacles inside the tanks present a problem. To make such remotely operated vehicular systems more flexible and reliable, this study investigates the fundamental requirements and replaces the crawler with a remotely operated submersible. The critical review of currently available ROVs showed that it would be difficult to procure such a vehicle and so it was decided to develop a new ROV, where aspects of operational environment (use in different petrochemical fluids), high lateral stability as well as advantageous design with respect to the subsequent controller design have been taken into account. It has been shown that this design strategy led to a vehicle where linear controller design strategies could be applied. An analysis of its suitability for use in different petrochemical fluids is provided by a detailed study of the materials that have been used and the flexibility to adjust its buoyancy which has been built in. The lateral stability of the vehicle which is a prerequisite to performing the desired plate thickness measurement is demonstrated and the reliability and robustness of the control system that was employed is also considered. A final field experiment has shown the reliable interaction of the system components and that the inspection system provides a useful and desirable capability for use under field conditions. Finally, an analysis of the system's performance has also shown its economic viability.

Orientador: Antonio Celso Fonseca de Arruda / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-06T20:39:40Z (GMT). No. of bitstreams: 1 Novaes_AlexandreBenedito_M.pdf: 2452563 bytes, checksum: 94c8f5f390d6f6ec81d9a33c048027cb (MD5) Previous issue date: 2006 / Resumo: Neste trabalho, são apresentados diferentes modelos de Estações para Inspeção Técnica Veicular, de maneira a dar opções de adequar, o mais racionalmente possível, a sua instalação em diferentes regiões do país, dependendo da densidade de veículos, criando condições de minimizar custos da inspeção e ao mesmo tempo mantendo, também, uma distância adequada ao usuário. As propostas consideram Estações de diferentes produções, desde a alta (370 veículos/dia) até a baixa (15 veículos/dia), com o objetivo de ser uma ferramenta para avaliação de custos. Os equipamentos propostos e a metodologia da inspeção estão baseados em experiência internacional, com adequações à realidade brasileira. A seleção correta do modelo de Estação a ser utilizado tem fundamental importância no levantamento do valor final da inspeção,permitindo a determinação de custos de investimento e custeio / Abstract: This work presents different models of Stations for Technical Vehicular Inspection in order to provide options to adequate, as rationally as possible, their installation in different regions of the country, depending upon the density of vehicles and thus creating conditions to minimize costs with inspection and at the same time keeping an adequate distance from users. These proposals consider Stations of different productions, from the highest (370 vehicles per day), to the lowest (15 vehicles per day), with the scope of being a tool for evaluation of costs. The equipments suggested and the methodology of inspection are based on an international experience adequate to brasilian reality. The correct selection ofthe Station models to be utilized have fundamental importance in the evaluation of the final value of inspection, permitting this way to determine costs of investment and daily expenses / Mestrado / Materiais e Processos de Fabricação / Mestre em Engenharia Mecânica

This thesis investigates new convex optimisation techniques for motion and pose estimation. Numerous computer vision problems can be formulated as optimisation problems. These optimisation problems are generally solved via linear techniques using the singular value decomposition or iterative methods under an L2 norm minimisation. Linear techniques have the advantage of offering a closed-form solution that is simple to implement. The quantity being minimised is, however, not geometrically or statistically meaningful. Conversely, L2 algorithms rely on iterative estimation, where a cost function is minimised using algorithms such as Levenberg-Marquardt, Gauss-Newton, gradient descent or conjugate gradient. The cost functions involved are geometrically interpretable and can statistically be optimal under an assumption of Gaussian noise. However, in addition to their sensitivity to initial conditions, these algorithms are often slow and bear a high probability of getting trapped in a local minimum or producing infeasible solutions, even for small noise levels. In light of the above, in this thesis we focus on developing new techniques for finding solutions via a convex optimisation framework that are globally optimal. Presently convex optimisation techniques in motion estimation have revealed enormous advantages. Indeed, convex optimisation ensures getting a global minimum, and the cost function is geometrically meaningful. Moreover, robust optimisation is a recent approach for optimisation under uncertain data. In recent years the need to cope with uncertain data has become especially acute, particularly where real-world applications are concerned. In such circumstances, robust optimisation aims to recover an optimal solution whose feasibility must be guaranteed for any realisation of the uncertain data. Although many researchers avoid uncertainty due to the added complexity in constructing a robust optimisation model and to lack of knowledge as to the nature of these uncertainties, and especially their propagation, in this thesis robust convex optimisation, while estimating the uncertainties at every step is investigated for the motion estimation problem. First, a solution using convex optimisation coupled to the recursive least squares (RLS) algorithm and the robust H filter is developed for motion estimation. In another solution, uncertainties and their propagation are incorporated in a robust L convex optimisation framework for monocular visual motion estimation. In this solution, robust least squares is combined with a second order cone program (SOCP). A technique to improve the accuracy and the robustness of the fundamental matrix is also investigated in this thesis. This technique uses the covariance intersection approach to fuse feature location uncertainties, which leads to more consistent motion estimates. Loop-closure detection is crucial in improving the robustness of navigation algorithms. In practice, after long navigation in an unknown environment, detecting that a vehicle is in a location it has previously visited gives the opportunity to increase the accuracy and consistency of the estimate. In this context, we have developed an efficient appearance-based method for visual loop-closure detection based on the combination of a Gaussian mixture model with the KD-tree data structure. Deploying this technique for loop-closure detection, a robust L convex posegraph optimisation solution for unmanned aerial vehicle (UAVs) monocular motion estimation is introduced as well. In the literature, most proposed solutions formulate the pose-graph optimisation as a least-squares problem by minimising a cost function using iterative methods. In this work, robust convex optimisation under the L norm is adopted, which efficiently corrects the UAV’s pose after loop-closure detection. To round out the work in this thesis, a system for cooperative monocular visual motion estimation with multiple aerial vehicles is proposed. The cooperative motion estimation employs state-of-the-art approaches for optimisation, individual motion estimation and registration. Three-view geometry algorithms in a convex optimisation framework are deployed on board the monocular vision system for each vehicle. In addition, vehicle-to-vehicle relative pose estimation is performed with a novel robust registration solution in a global optimisation framework. In parallel, and as a complementary solution for the relative pose, a robust non-linear H solution is designed as well to fuse measurements from the UAVs’ on-board inertial sensors with the visual estimates. The suggested contributions have been exhaustively evaluated over a number of real-image data experiments in the laboratory using monocular vision systems and range imaging devices. In this thesis, we propose several solutions towards the goal of robust visual motion estimation using convex optimisation. We show that the convex optimisation framework may be extended to include uncertainty information, to achieve robust and optimal solutions. We observed that convex optimisation is a practical and very appealing alternative to linear techniques and iterative methods.

D.Econ.

With the world's population expected to reach nine billion by 2050, agricultural production will have to double to meet this growing demand. Hence, a need for better infrastructure to enhance farming efficiency becomes apparent. There are a number of solutions that have been developed to date that are commercially available. They range from genetically modified seeds and bio/green fertilizers to advanced farming machinery amongst others. However most of the farming equipment developed has drawbacks such as: heavy weight – this leads to reduced yields due to soil compacting; human dependency – constant monitoring and controlling is needed; light dependency – excludes usage during the night or when visibility is poor. Therefore, a possible solution will be researched to enhance the evolution of farming equipment. Furthermore, a model will be developed for testing and verifying the research.