Thesis (Ph. D.)--West Virginia University, 2005. / Title from document title page. Document formatted into pages; contains x, 144 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 117-120).

Thesis (Ph. D.)--Civil and Environmental Engineering, Georgia Institute of Technology, 2006. / Dr. Jennifer Michaels, Committee Member ; Dr. Jacek Jarzynski, Committee Member ; Dr. Jianmin Qu, Committee Member ; Dr. Laurence J. Jacobs, Committee Chair ; Dr. Kimberly E. Kurtis, Committee Co-Chair.

Thesis (MTech (Mechanical Engineering))--Cape Peninsula University of Technology, 2017. / Infrared thermography (IRT) is a non-contacting, non-destructive testing (NDT) technique that provides relatively fast results from inspections; for example, in the detection of defects in engineering components and in systems' condition monitoring. This study examines the use and possible effectiveness of infrared thermography for the detection of faults and defects in just a few aspects that one encounters in the vast mechanical maintenance arena. The study discusses three aspects of infrared thermography, namely internal leaks inspections using passive infrared thermography, pulse thermography and induction thermography both active IRT NDT techniques for the detection of subsurface and surface defects. The promising results that were obtained by performing an experiment in the laboratory using a model fluid handling pipe network, with three isolation valves connected in parallel, encouraged performing inspections in an operating power plant, where it was suspected that there were leaks from safety and drain isolation valves. In both situations, the results were obtained in a short period of time and indicated that passive infrared thermography can detect internal leaks in pipe networks. Pulsed thermography is an active non-contacting non-destructive testing technique used to detect subsurface defects in monolithic materials and delamination's in composites. In the particular experiment that was performed pulse thermography was benchmarked with the conventional technique of ultrasound testing. PVC, stainless steel and mild steel specimens manufactured with flat bottom holes (as models of subsurface defects) were subjected to pulse thermography. The time duration to detect the presence of a defect represented by a temperature contrast or a hot spot on the specimen's surface was approximately a couple of seconds following the thermal excitation. No further characterization of the defect was possible with the technique. In contrast when using the ultrasound testing technique to test the specimens, it took considerable time to detect the defects, however, data in terms of size and depth beneath the surface became available thus enabling their full characterization.

The thesis focused on the development and analysis of a distributed parameter model that apply to a class of an autonomous hyper-redundant slender robotic systems interacting with the environment. The class of robotic devices that will be implemented based on the modelling in this thesis, is intended to be autonomously deployed in unknown, unstructured environments, in which it has to accomplish different missions by being able to robustly negotiate unknown obstacles and unpredictable and unmodelled irregularities. Therefore the mechanical models presented here are inspired by some features of a class of organisms - millipedes and centipedes - that possess many of these capabilities. Specifically, these organisms posses flexible slender bodies whose shape morphs according to the curvature of the terrain on which they operate, and possess a highly redundant system of legs that couple the body with the terrain providing propulsion for forward or backward motion, with the high number of legs ensuring a robust distributed contact even on very irregular substrates. The mechanical model that naturally captures the structure of millipede bodies is the Timoshenko beam, which is therefore adopted here. Moreover, the coupling with the environment is modeled by a system of compliant elements, that provides a distributed support analogous to the one exerted by millipedes' legs; such support provides a distributed force that in a control framework is treated as the actuation for shape morphing, so that the body of the system deforms according to the curvature of the substrate. By using a Lagrangian mechanics approach, the evolution of the system is described in a suitable product Hilbert space, in which rigid body degrees of freedom and deformations are coupled. This formulation allows to pose a distributed parameter control problem in which shape morphing and locomotion are dictated by the interaction with the substrate, which in this case is approximated as rigid (that is, the profile of the substrate is not affected by the interaction with the system). Additionally, by modeling the material response of the substrate with a simple linear viscoelastic model, we pose an estimation problem in which, by measuring deformations and/or stresses on the body represented by the beam, we can infer the material properties of the substrate. In this case, the overall coupled system is modelled as a beam on a multi-layer viscoelastic foundation. Predictions of this sensor model are in good agreement with published results, suggesting that the system can be used in a versatile way as an autonomous agent operating in a generic environment, and simultaneously as a sensor that could inform the action of the system itself, or that could be used to monitor the environment. The modeling work done in this study opens the possibility for the implementation in engineering systems applied to environmental monitoring and health applications, in which we envision the system to be used to estimate material properties of living tissues, that can be correlated to the diagnosis of classes of diseases.

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<p>The group for non-destructive testing at Uppsala University has recently implemented the phase shift migration method, which is a method to focus images acquired unfocused using ultrasound. However, their work has been limited to 2D data, while for many applications the gathered data is 3D. This project has extended the old implementation to 3D data. The new implementation has been done in two different ways, giving one algorithm that works fast but needs much RAM, and one algorithm that takes long time but works on smaller computers, not demanding as much memory. The fast algorithm works faster than the time it takes to acquire the raw data, which makes real-time use realistic. To test the performance of the two algorithms with respect to image improvement, both against each other and against the previous 2D implementation, a number of experiments were carried out, which showed that, apart from processing time, the two new algorithms were equal in performance. The experiments also showed that the obtained resolution in both x- and y-directions matched the theoretical discussion.</p>

The group for non-destructive testing at Uppsala University has recently implemented the phase shift migration method, which is a method to focus images acquired unfocused using ultrasound. However, their work has been limited to 2D data, while for many applications the gathered data is 3D. This project has extended the old implementation to 3D data. The new implementation has been done in two different ways, giving one algorithm that works fast but needs much RAM, and one algorithm that takes long time but works on smaller computers, not demanding as much memory. The fast algorithm works faster than the time it takes to acquire the raw data, which makes real-time use realistic. To test the performance of the two algorithms with respect to image improvement, both against each other and against the previous 2D implementation, a number of experiments were carried out, which showed that, apart from processing time, the two new algorithms were equal in performance. The experiments also showed that the obtained resolution in both x- and y-directions matched the theoretical discussion.

Thesis (M. S.)--Mechanical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Ume, I. Charles; Committee Member: Mayor, J. Rhett; Committee Member: Sadegh, Nader. Part of the SMARTech Electronic Thesis and Dissertation Collection.

Thesis (Ph. D.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains xiv, 185 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 170-176).

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