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 47 for “"tomographic reconstruction"”.
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Tomographic reconstruction with adaptive sparsifying transforms
… 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 representations. In particular, the synthesis dictionary learning …
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Ultrasonic laboratory tests of geophysical tomographic reconstruction
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric and Planetary Sciences, 1986.
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Tomographic reconstruction of the morphology of silicon nanoparticleclusters
… the tomograms are reconstructed, resulting in reconstructions which possess significant artifacts. This limitation is overcome by the development of a new correlation based alignment technique which produces superior alignment when compared to previous techniques, especially in the case of …
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Tomographic Reconstruction of Wavefront Aberrations using Multiple Laser Guide Stars
Tomographic reconstruction using multiple laser guide stars (MLGS) will be required by the next generation of extremely large (30 m class) telescopes (ELT). Modal decomposition of wavefront phase using Zernike polynomials is a widely used technique in adaptive optics (AO) research. However, this …
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Tomographic reconstruction and sub-surface imaging of porous nitride semiconductors
… microscope (FIB-SEM) allowed for volumetric reconstructions of porous GaN DBRs with microscale volume and nanoscale spatial resolution. In our highest-resolution dataset, voxel dimensions of (2 x 2 x 5.1) nm were achieved by leveraging automated tracking and post-process interpolation of …
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Algorithms for Tomographic Reconstruction: Fast Back Projection and Cardiac Computed Tomography
The second problem we address is that of the reconstruction of a movie of the moving heart from fan-beam tomographic projections. We consider the problem within a state-space framework and present a reconstruction algorithm based on the ensemble Kalman filter. The algorithm reconstructs a movie of …
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Wavelet transform-based multi-resolution techniques for tomographic reconstruction and detection
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Nuclear Engineering, 1994.
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Tomographic reconstruction of polygons from knot locations and chord length measurements
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1993.
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Algorithms for Tomographic Reconstruction of Rectangular Temperature Distributions using Orthogonal Acoustic Rays
… two microphones is developed and integrated with tomographic techniques to reconstruct temperature contours. A low velocity plume at around 450 °F exiting through a rectangular duct (3.25 by 10 inches) was used for validation and reconstruction. 0.3 % static temperature relative error compared …
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Spatially Resolved Equivalence Ratio Measurements Using Tomographic Reconstruction of OH*/CH* Chemiluminescence
… (camera images). High resolution tomography reconstructions require a selection of projection angles around the flame, while captured chemiluminescence of radical species intensity fields can be used to determine local fuel-air ratios. In this work, a tomographic reconstruction algorithm …
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Tomographic Reconstruction of 2-D Atmospheric Trace Gas Distributions from Active DOAS Measurements
Applying the tomographic principle to active DOAS remote sensing leads to a novel technique for the measurement of atmospheric trace gas distributions. Standard analytical methods for the reconstruction of a scalar field from its line integrals cannot be used due to low numbers of light paths …
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Development and tomographic reconstruction of an innovative MBI device for the early breast cancer diagnosis
… or limited angle tomography (LAT) for a 3-D reconstruction of the breast lesion and its depth localization. The current work has been focused on the improvements of the MBI system in terms of more detailed calibration and characterization in realistic conditions, the development of realistic …
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Full waveform inversion of ultrasonic phased array data for the tomographic reconstruction of heterogeneous media for NDT
… Monte Carlo method (rj-MCMC), to perform the tomographic reconstruction in the form of a posterior distribution. The reconstructed wave speed maps are then used in conjunction with an imaging algorithm (TFM), to provide enhanced flaw imaging. The quality of the imaged flaws are then quantified …
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Automated 3D reconstruction of Lodox Statscan images for forensic application
… main objectives of this project are to perform tomographic reconstruction with manually scanned projection data from a Lodox Statscan full body digital radiography system, and to produce tools to allow automated generation of information required to perform the tomographic reconstruction.
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Near-Field Scanning Optical Tomography: Theory and Modalities
… of the probe is studied for the possibility of a tomographic imaging with a fixed-angle illumination. Alternatively, a broadband illumination with one fixed angle or a limited number of angles of incidence, with coherent measurement, may be employed to obtain tomographic reconstruction. Forward …
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Atomic-scale and three-dimensional transmission electron microscopy of nanoparticle morphology
… GaPd2 nanocatalysts and advancement of electron tomographic methods for high-fidelity three-dimensional analysis. Going beyond preceding analyses, high-resolution annular dark-field imaging is used to verify successful nano-sizing of the intermetallic compound GaPd2. It also reveals catalytically …
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A Method for Measuring Spatially Varying Equivalence Ratios with Application to Thermoacoustics
… the process of high-resolution tomography reconstructions in this work allowed for flame tomography coupled with chemiluminescence emissions to be used for spatially resolved phase averaged equivalence ratio measurements. This is important as variations in local equivalence ratios can have …
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Signal Processing Issues in Reflection Tomography
… objects, we formulate the problem as a 3-D tomographic reconstruction problem. We have developed software to simulate lidar returns at airborne receivers using the bistatic lidar return equations. Our simulator can model multiple scattering and absorption for various water types and system …
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Studies of Atmospheric Gravity Waves in the Mesopause Region Using Airglow Imaging
… techniques have been compared in the tomographic reconstruction processes of retrieving synthetic wave structures. Various combinations of number and separation of imagers are considered for showing the effect of system geometry on the reconstruction performance. Further studies on …
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