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 45 for “"k-space"”.
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Magnetic resonance image reconstruction from highly undersampled K-Space data using dictionary learning
… accurate reconstruction from undersampled k-space data. Recent CS methods have employed analytical sparsifying transforms such as wavelets, curvelets, and finite differences. In this thesis, we propose a novel framework for adaptively learning the sparsifying transform (dictionary), and …
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The Complete Preimage of Euclidean K-Space Under an Open Mapping With The1-Regular Property and Whose Point Inverses Are Open 2-Cells Is Euclidean(k Plus 2)-Space
Made available in DSpace on 2014-12-11T18:23:45Z (GMT). No. of bitstreams: 1 7206926.pdf: 3145209 bytes, checksum: 3212c154ca63432b3b2871295b0d3241 (MD5) Previous issue date: 1971
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Accelerating magnetic resonance imaging by unifying sparse models and multiple receivers
… the spatial Fourier transform domain (called k-space) and the image is reconstructed using an inverse discrete Fourier transform. The affordability, availability, and applications of MRI remain limited by the time required to sample enough points of k-space for the desired field of view (FOV), …
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Fast magnetic resonance spectroscopic imaging using RF coil arrays
… coils has opened opportunities for fast k-space encoding schemes that are already used in structural imaging. At the same time, receive-coil arrays using 4 and 23 channels have been developed and reported to produce improved SNR over conventional quadrature detection by single coils. Fast …
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Algorithms and lower bounds for sparse recovery
… * Recover block-sparse vectors with O(k) space and a 1 + [epsilon] approximation. Previous algorithms required either w(k) space or w(1) approximation.
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Acceleration of Subtractive Non-contrast-enhanced Magnetic Resonance Angiography
… chapters. Chapter 5 investigates the optimal k-space sampling patterns for the 3D accelerated femoral artery FBI sequence. A variable density Poisson-disk with a fully sampled centre region and missing partial Fourier fractions is employed for k-space undersampling in the ky-kz plane. Several …
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Dynamic Contrast-Enhanced MR Microscopy: Functional Imaging in Preclinical Models of Cancer
… with a quasi-uniform distribution of points in k-space was used for sampling temporally resolved datasets. These volumes were reconstructed with three different k-space filters encompassing a range of possible keyhole strategies. The effect of k-space filtering on spatial and temporal resolution …
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Advanced parallel magnetic resonance imaging methods with applications to MR spectroscopic imaging
… regularization for parallel MRI with arbitrary k-space sub-sampling is developed. Regularization methods using the singular value decomposition of the encoding matrix and pre-conditioning of the forward model are proposed to desensitize the solution from data noise and model errors. Variable …
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Distortion correction in magnetic resonance imaging using the simulated point spread function
… with this approach is shown to be better than k-space based iterative reconstructions and is robust to high differentials in magnetic field maps when we use an optimal trajectory. In addition, this technique is well-suited to parallel implementation, as the system matrix used is sparse.
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Optimization of Fast MR Imaging Technologies using the Case-PDM to Quantitatively Assess Image Quality
… acquired, reconstructed image to slower, full k-space, high quality reference image. We used advanced human observer experimental methods (DSCQS, FMT, 2AFC) to prove these methods on the contexts of human-model correlation, comparability of model evaluation scores across different image contents, …
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Optical properties of confined and unconfined excitons in semiconductor quantum heterostructures
… aid of supercomputer and recently developed k-space sampling technique we can deal with both discrete exciton states and exciton continuum states properly and hence the photoabsorption coefficient. These techniques are applied to calculate the electroabsorption, resonant Raman scattering in …
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Incorporating default risk into the Black-Scholes model using stochastic barrier option pricing theory
… by generalizing the reflection principle to k-space to determine the appropriate transition density function. The European analytical valuation formula has a straightforward economic interpretation and preserves much of the intuitive appeal of the traditional Black-Scholes model. The hedging …
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Deep learning-based medical image reconstruction for multi-contrast magnetic resonance imaging
… acquisition domain of MRI, known as the *k*-space, which is associated with, but different from the image domain. To allow for improved reconstruction with information in both domains, we present a dual-domain reconstruction framework with specifically designed regularisations to exploit the …
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Electronic band structure variations in photothermal catalytic materials
… along a universal high-symmetry path in k-space, we can compare how temperature induced asymmetric lattice changes impact the electronic properties of the different materials and the overall stability of the proposed photothermal catalytic device. These insights help identify what materials …
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Improved Techniques For Acquisition and Analysis of Dynamic Contrast-Enhanced Magnetic Resonance Imaging For Detecting Vascular Permeability In The Central Nervous System
… was implemented with a novel and truly centric k-space segmentation scheme. In addition, an original multi-step curve fitting procedure was developed to increase the accuracy of T1 estimation. A view sharing acquisition method was implemented to increase temporal resolution, and a novel …
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Study of exciton localized by random potential in indirect gallium arsenide phosphide alloys
… and is associated with the X-point in K-space. We interpret the MO band as due to excitons localized by the random potentials in the alloys. Lifetime measurements show that the Mx/0 excitons are relatively long lived (tens of microseconds) and it varies over the spectral regions of the M~ …
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Simultaneous multislice spiral and EPI chemical shift imaging
… I discuss the sequences used to encode the k-space, where spiral trajectories are an efficient choice. Therefore, a method that can be used for SMS spiral spectroscopy acquired data is proposed. The proposed method accelerates the minimum scan time of 2D excitation for a single average by a …
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Adaptive functional magnetic resonance imaging
… conventional encoding methods based on k-space acquisition have limited spatial selectivity. To improve it, we propose an adaptive fMRI method using non-Fourier, spatially selective RF encoding. This method follows a strategy of zooming into the locations of activation by progressively …
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