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 26 for “"tomographic images"”.
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Generation of high resolution tomographic images for NDT applications
… for the generation of quantitative ultrasonic images in non-destructive testing have generally involved a substantial cost in terms of data storage and computational time, and have thus found limited application. Preference has therefore been given to the more straightforward imaging methods, …
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Analysis of tomographic images: quantitative methods for soil pore structure
… vast quantity of information present within a tomographic image, lead to significant difficulty in the accurate interpretation of these images. This thesis deals with problems of acquisition, assessment, processing and measurement for such images, applying unsupervised (fully automatic) methods …
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Computational modeling and simulation of composite materials based on tomographic images
… of heterogeneous composite materials based on tomographic images of material specimens. Of particular interest are microvascular materials containing embedded micro-channnels through which a coolant or self-healing agent can be circulated. Such materials have important applications to aircraft, …
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Iterative Methods for the Reconstruction of Tomographic Images with Unconventional Source-detector Configurations
… geometry is commonly used in reconstruction of images by filtered back projection technique. A clam-shell structure consists of two semi-cylindrical braces that fold together over the patient's body and connect at the top. A parallel plate structure uses two fixed flat or curved plates on either …
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Registration of Tomographic Images to X-ray Projections for Use in Image Guided Interventions
… which is guided using 2D fluoroscopy images. <br/><br/>An algorithm has been designed to obtain the pose of a CT volume with respect to a single fluoroscopy image. The registration algorithm is based on the production of digitally reconstructed radiographs from the CT volume, which are …
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First-order gradient regularisation methods for image restoration: reconstruction of tomographic images with thin structures and denoising piecewise affine images
… of TV and $L^p$ seminorms for denoising images with piecewise affine structures. In the first part of this thesis, we present a novel variational model for PET reconstruction. During a PET scan, we encounter two different spaces: the sinogram space that consists of all the PET data …
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Scattering and Absorption of Photons in Emission Computed Tomography
… of photons have on the ability to produce tomographic images of an internal gamma-ray source distribution. Computer simulations of the photon-transport process and the collimator-detector system are used in this study so that these scattering effects can be examined independently from other …
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Seismic tomographic imaging reveals possible lithospheric erosion beneath Trans-Pecos Texas and Southeastern New Mexico.
… distances of 30- 90° were used to create tomographic images with FMTOMO. We present three-dimensional P and S tomographic models of the crust and upper mantle beneath the edge of the rift that confirm the anomaly's existence and show that it is more laterally extensive than was indicated …
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X-ray attenuation techniques to explore the dynamics of water in porous media
… measurements of X-ray attenuation data and tomographic images during the outflow experiment. With this setup experiments were done to test the validity of Richards' equation for different boundary conditions. Therefore, the measured vertical distribution of water was compared with simulated …
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Tomographic reconstruction with adaptive sparsifying transforms
… while maintaining the quality of reconstructed images. Methods which exploit the sparse representations of tomographic images have long been known to improve the quality of reconstructions from low-dose data. Recent work has shown the promise of adaptive, rather than fixed, sparse …
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Ambient noise interferometry and surface-wave array tomography in southeastern Tibet
… which may, in turn, degrade the accuracy of the tomographic models. Under the assumption of plane-wave propagation, we developed an iterative method to estimate ambient noise energy distribution, phase velocity bias primarily due to uneven noise energy distribution, and azimuthally anisotropic …
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Image-Based Pore-Scale Modeling of Inertial Flow in Porous Media and Propped Fractures
… of real porous media from X-ray computed tomographic images. Rigorous pore-scale finite element modeling using unstructured mesh is developed and implemented in proppant fractures. The macroscopic parameters permeability and non-Darcy coefficient are obtained from simulations. The inertial …
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Monte Carlo Simulations of Novel Scintillator Detectors and Dosimetry Calculations
… to acquire both echographic and scintigraphic images to let the medical operator obtain the complete anatomic and functional information for tumor diagnosis. The scintigraphic part of the detector is simulated by GEANT4 and first attempts to reconstruct tomographic images have been made using …
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Teleseismic imaging of the Slave craton and implications for the assembly of cratonic lithosphere
… craton in Canada. First, I perform surface wave tomographic inversions to constrain the depth dependence of Rayleigh wave phase velocity, shear wave velocity, and azimuthal anisotropy of the Slave cratonic lithosphere. The tomographic images reveal high shear wave velocities associated with a …
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Teleseismic tomography beneath Hi-CLIMB station array in western Tibetan Plateau
… 84.2° E, respectively. The resulting horizontal tomographic images exhibit a high-slow-high velocity structure from north end of the array to the south. The two boundaries separating the velocity structures are Bangong-Nujiang suture (BNS) and the Indus-Yarlung suture (IYS). Positive velocity …
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Seismic investigations of the northern Transantarctic Mountains
… northern TAMs and to assess uplift. Surface wave tomographic images indicate a previously unidentified low shear wave velocity anomaly beneath the northern TAMs, with faster seismic velocities behind the TAMs front. The low shear wave velocity anomaly is interpreted as reflect rift-related …
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Passive Seismic Tomography and Seismicity Hazard Analysis in Deep Underground Mines
… of seismic events are used as sources of tomographic imaging survey. An initial velocity model is established according to properties of a rock mass, then velocity structure is reconstructed by velocity inversion to reflect the anomalies of the rock mass. Mining-induced seismicity and …
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Diagnostic imaging of the tympanic bulla and temporomandibular joint in the dog, cat and rabbit.
… of anatomical features on corresponding tomographic images. Ultrasound imaging of this region has not been widely reported but allowed evaluation of the TB in all three species, although the information obtained regarding the TMJ was limited. Directly acquired computed tomography (CT) and …
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