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 20 of 46 for “"X-ray tomography"”.
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Chemical analysis of polymer blends via synchrotron X-ray tomography
… polymer blends are of great importance. X-ray tomography has been used to obtain spatial chemical information about various polymer blends. The spatial images are acquired with synchrotron X-ray tomography because of its rapidity, good spatial resolution, large field-of-view, and elemental …
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Stability, Range and Statistical Aspects of non-Abelian X-ray tomography
The non-Abelian X-ray transform on a Riemannian manifold with boundary (M,g) is a nonlinear map A → CA that associates to a matrix-valued and possibly direction-dependent function A, referred to as attenuation, its scattering data CA. The scattering data records initial-to-end-value maps for the …
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SEARCHLIGHT CT: A NEW REGULARIZED RECONSTRUCTION METHOD FOR HIGHLY COLLIMATED X-RAY TOMOGRAPHY
… for image reconstruction in collimated Computed Tomography called Searchlight CT. The method significantly reduces the overall radiation exposure when primarily the reconstruction of a specified region of interest is required. To achieve this, the Searchlight CT approach restricts the acquisition …
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Digital Test of Composite Material Using X-Ray Tomography and Finite Element Simulation
… method for material characterization based on x-ray tomography and finite element method. The introduction of tomography technology, such as x-ray tomography into engineering field makes it possible to obtain material microstructure without disturbing the phase configuration. Along with the …
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Digital Simulative Test of Asphalt Mixtures Using Finite Element Method and X-Ray Tomography Images
… on actual microstructure reconstructed from X-ray tomography images. In the study, the microstructure of AC is obtained through the analysis of X-ray images, which included the digital information of the microstructure for the scanned specimen. In the simulations the three phases, mastic …
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Behaviours of bifilms in A356 alloy during solidification: developing observation techniques with 3-D micro x-ray tomography
… was designed using a gating system. Micro X-ray tomography (Skyscan 1702) was used to establish the best specimen diameter and scanning conditions, including exposure time, magnification, rotation angle and rotation-step angle. Following scanning, the specimens were re-melted for 1, 2, 3, 4 …
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Investigating variables affecting heap (bio)leaching through determining access to sub-surface mineral grains by micro-scale X-ray tomography
… using high resolution, non-destructive 3D X-ray micro-Computed Tomography (μCT), an imaging technique for investigation of internal structure of opaque objects. X-ray μCT has previously been developed and used for investigation of different aspects of heap leaching. In the current study, the …
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Binder Film Thickness Effect on Aggregate Contact Behavior
… will also be introduced. By using the cabinet x-ray tomography system, the displacement and resistant force of a system of particles bonded by a thin layer binder are measured and recorded. Then, the results are compared with the theoretical solutions of a normal compliance model for a system …
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Description and reconstruction of microscopic random heterogenous media in order to estimate macroscopic hydraulic functions
… Based on the measured pore geometry (with x-ray tomography), a lattice-Boltzmann Navier-Stokes equation solver was used to calculate the velocity field and the hydraulic conductivity. Additionally, the pressure-saturation relation of a primary drainage process was derived from a …
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Physics-assisted machine learning for X-ray imaging
X-ray imaging is capable of imaging the interior of objects in two and three dimensions non-invasively, with applications in biomedical imaging, materials study, electronic inspection, and other fields. The reconstruction process can be an ill-conditioned inverse problem, requiring regularization …
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An algebraic reconstruction technique (ART) for the synthesis of three-dimensional models of particle aggregates from projective representations
… aggregate mix were scanned using optical and X-ray tomography techniques to generate 2-D multiple projections and synthesize the 3-D particle shape. This research work proves useful for generating realistic shapes for discrete element applications or in obtaining more fundamental understanding …
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Damage of concrete with epoxy coated reinforcement due to corrosion, freeze-thaw and fatigue with application to bridge decks
… more slowly in ECR. The second method utilized X-ray tomography to obtain images of internal cracking in the specimens. Image-processing software was used to compute the volume of cracks inside the specimens. It took about 4 times longer for the ECR specimens to have the same volume of cracks as …
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Development of a motion-free tomographic imaging system
Computed tomography (CT) is the clinical standard for diagnosing many emergent medical conditions, such as stroke and traumatic brain injuries. Unfortunately, the size, weight, and expense of CT systems make them inaccessible for patients outside of large trauma centers. We have designed a module …
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Optimization of optical computed tomography techniques for the synthesis of particle aggregate models
… of 2-D projections. Furthermore, optical tomography methods using the Algebraic Reconstruction Technique (ART) algorithm has proved capable of synthesizing 3-D shapes from 2-D projections, with accuracy comparable to that obtained by an X-ray microtomograph (the "gold" standard).</p> …
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A 3-D tomographic survey of compound chondrules in two carbonaceous chondrites : Acfer 139 and Renazzo
… and Keil, 1981). This thesis introduces x-ray tomography as a new method of measuring and surveying CCs; and explores the advantages and limitations of this method. A 3-D tomographic study of two CR carbonaceous meteorites, Acfer139 and Renazzo, reveals a higher frequency of compound …
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Data-driven X-ray Tomographic Imaging and Applications to 4D Material Characterization
X-ray tomography is an imaging technique to inspect objects' internal structures with externally measured data by X-ray radiation non-destructively. However, there are concerns about X-ray radiation damage and tomographic acquisition speed in real-life applications. Strategies with insufficient …
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Fabrication & Mechanical Properties of Hastelloy-X Matrix Ceramic Composite
… Composites were characterized using x-ray tomography and scanning electron microscopy (SEM) imaging to analyze the pore infiltration. Rockwell hardness and nanoindentation were measured to determine changes in material properties. Through porosity calculations and SEM imaging, it was …
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