Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 12 of 12 for “"Focusing technique"”.
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A unified approach to complex seismic imaging problems
… information from the data, incorporates a depth focusing technique for improved image resolution and utilizes user-interaction and geologic input to guide and constrain the imaging process. I first describe a fast and accurate dynamic ray-tracing scheme in heterogeneous media which allows complex …
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Time domain synthetic aperture radar image processing using fast factorised backprojection
… is a Synthetic Aperture Radar (SAR) focusing technique which uses Filtered Backprojection(FBP) to produce high quality images in the spatial domain at speeds which rival spectral domain SAR focusing methods. Synthetic Aperture Radar (SAR) focusing is fundamentally a matched filtering …
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Spatiotemporal processing and time-reversal for underwater acoustic communications
… and equalization, as well as time-reversal techniques, have been used over these channels to reduce the effect of ISI. As an alternative, a spatiotemporal focusing technique had been proposed. This technique is similar to time-reversal but it explicitly takes into account elimination of ISI. …
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Maternal Guilt: An Existential Phenomenological Study of the Early Experiences of First-Time Mothers
… using an adapted research methodology utilizing Focusing Technique (Gendlin, 1981), their embodied reflections about a particular memory of feeling maternal guilt. This study utilizes procedures explicated by Colaizzi (1978), Giorgi & Giorgi (2003), Todres (2007), von Eckartsberg (1998), Walsh …
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Fluid Mechanics for Biomedical Applications: Weakly Viscoelastic Electrospray, Flow Focusing and Collapsible Channel Models
… ii) the emergence of whipping effect on the Flow Focusing technique, and iii) fluid-structure interaction (FSI) phenomena implementing a 2D collapsible channel model. i) A systematic, theoretical comparison of a Newtonian fluid, and a non-Newtonian one modelled using an Oldroyd-B model was …
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Velocity-difference induced focusing in capillary electrophoresis and preparative capillary electrophoresis
Velocity-difference induced focusing (V-DIF) with a dynamic pH junction in capillary electrophoresis (CE) using a sample with a pH different from that of the background electrolyte (BGE) was developed in our group, but the mechanism was not well understood. In this work, the mechanism of this …
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Enhanced ultrasonic techniques for inspection of pressure tubes
… inspection approaches utilising ultrasonic techniques are technically challenging due to transducer alignment caused by the tube dimensional changes. This Thesis focuses on enhancing ultrasonic techniques to improve the inspection accuracy by introducing signal processing algorithms and …
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Ultrasonic sensor platforms for Non-Destructive Evaluation
… wave scanning by comparison with both analytical techniques and more computationally intensive commercial finite element/diference codes. Starting with fundamental dispersion data, the work goes on to describe the simulation of wave propagation and the subsequent interaction with artificial …
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Ultrasonic nondestructive evaluation and imaging of defects in reinforced cementitious materials
… assessment of structures. Among many other NDE techniques, ultrasonic methods play a prominent role in the both quantitative and qualitative assessment of discontinuities in reinforced cementitious materials. Due to the heterogeneous nature of concrete, ultrasonic waves are highly scattered and …
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Single cell analysis by capillary electrophoresis with laser-induced native fluorescence detection
… fluorescence detection (CE-LIF). This technique was chosen due to its high separation efficiencies, small sample volumes and sensitive detection. Native fluorescence was used, in which the analyte was not tagged with a fluorophore. 275-nm excitation gave attomole (amol = 10-18 mol) …
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Aerosol carbon nanotube production via scalable microplasma synthesis of catalyst nanoparticles
… is investigated, and a dielectric gradient focusing technique is developed to reduce variability and extend the lifetime of operation. Second, a FC-CVD system is built and integrated with the microplasma reactor and used to explore CNT synthesis on iron-carbon catalyst aerosols. Controlling …
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Applying synthetic aperture, coded excitation, and tissue harmonic imaging techniques to allow ultrasound imaging with a virtual source
… transducer. To extend the region of focus, three techniques were examined. The first was the synthetic aperture focusing technique (SAFT), a well-studied method that allows focus at every distance instead of just one distance. Using this method, lateral resolution is restored and signal-to-noise …