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 18 of 18 for “"Tensor field"”.
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Zifazah: A Scientific Visualization Language for Tensor Field Visualizations
… and exploring 3D visualizations of diffusion tensor magnetic resonance imaging (DT-MRI or DTI) data. Unlike existing tools allowing flexible customization of data visualizations that are programmer-oriented, Zifazah focuses on domain scientists as end users in order to enable them to freely …
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Statistical Analysis on Diffusion Tensor Estimation
Diffusion tensor imaging (DTI) is a relatively new technology of magnetic resonance imaging, which enables us to observe the insight structure of the human body in vivo and non-invasively. It displays water molecule movement by a 3×3 diffusion tensor at each voxel. Tensor field processing, …
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Self-Sustaining Formation of Packets of Hairpin Vortices in a Turbulent Wall Layer
… local real eigenvector of the velocity gradient tensor field over almost the entire region occupied by the vortex. By using this feature, the backbone of a vortex can be constructed efficiently.
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Calculating 3D intramyocardial strain tensors in a single slice of myocardium using MRI
… for measuring 3D intramyocardial strain fields are limited to a handful of techniques. The only widely accepted method being the use of tagging in orthogonal image planes that requires the imaging of the entire myocardial volume, followed by lengthy and time consuming post processing. A …
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Comparison of two methods for two dimensional unstructured mesh adaptation with elliptic smoothing
… the mesh to match either a Riemannianmetric tensor field or an equal distribution of scalar weights. Forcing functions similar to those used for structured grids are employed such that the resulting meshes can be compared with those generated using the new adaptation method. Several test …
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Machine Learning and Field Inversion approaches to Data-Driven Turbulence Modeling
… provide improved closure for the Reynolds stress tensor field. The first approach uses machine learning to learn a general closure model from data. A novel framework is developed to train deep neural networks using experimental velocity and pressure measurements. The sensitivity of the RANS …
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A biomechanical investigation of the structure--function relationships in the human tongue
… myoarchitecture was studied with Diffusion Tensor MRI (DTI), which derived the spatial diffusion tensor field in the tongue. Since, diffusivity relates directly to myofiber orientation, this in vivo technique successfully produced a virtual anatomical atlas. In order to relate this 3D …
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Tensorial spacetime geometries carrying predictive, interpretable and quantizable matter dynamics
Which tensor fields G on a smooth manifold M can serve as a spacetime structure? In the first part of this thesis, it is found that only a severely restricted class of tensor fields can provide classical spacetime geometries, namely those that can carry predictive, interpretable and quantizable …
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Lagrangian analysis of vector and tensor fields: Algorithmic foundations and applications in medical imaging and computational fluid dynamics
<p>Both vector and tensor fields are important mathematical tools used to describe the physics of many phenomena in science and engineering. Effective vector and tensor field visualization techniques are therefore needed to interpret and analyze the corresponding data and achieve new insight into …
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Applications of differential geometry to high spin field theories
… constraint analysis of relativistic high spin field theories. As a starting point the coordinate dependent descriptions of the Lagrangian and Dirac-Bergmann constraint algorithms are reviewed for general second order systems. These two algorithms are then respectively employed to analyse the …
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Diffusion Tensor Imaging: Evaluation of Tractography Algorithm Performance Using Ground Truth Phantoms
Diffusion Tensor Magnetic Resonance Imaging (DT-MRI), also known as Diffusion Tensor Imaging (DTI), is a unique medical imaging modality that provides non-invasive estimates of White Matter (WM) connectivity based on local principal directions of anisotropic water diffusion. DTI tractography …
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Antisymmetric tensor portals to dark matter
… by the so-called “Kalb-Ramond antisymmetric tensor field” or “KR field”. This field first arose in string theory; if dark matter generated through the KR portal were to be detected, it would be the first experimental corroboration of the string theory (and supergravity) frameworks. We show …
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Anisotropic nonlinear PDE models and dynamical systems in biology
… is an anisotropy induced by an underlying tensor field. This innovation does not only lead to the ability to describe real-world phenomena more accurately, but also renders their analysis significantly harder compared to their isotropic counterparts. We discuss the role of anisotropic …
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Intramural mechanics in the human tongue
… myoarchitecture was studied with diffusion-tensor MRI. A slice select pulsed gradient stimulated echo pulse sequence was applied to derive the spatial diffusion tensor field in the tongue. Tensor eigenvectors and measures of anisotropy were used to derive a virtual anatomical atlas of the …
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A three-dimensional turbulent boundary layer upstream and around a junction vortex flow
… shear stress, mean velocity, and Reynolds stress tensor field are reported at several stations in the three-dimensional turbulent boundary layer region. Documentation of the flow edge conditions is provided as well as upstream initial conditions along a plane with measured mean velocity and …
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Modelling bottom stress in depth-averaged flows
… from the DRM to the DAM in the form of drag tensor with two components: one which scales the flow and one which rotates it. This eliminates the problem of traditional drag laws requiring the flow and bottom stress to be collinear. In addition , the drag tensor field is updated periodically so …
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Modelling bottom stress in depth-averaged flows
… from the DRM to the DAM in the form of drag tensor with two components: one which scales the flow and one which rotates it. This eliminates the problem of traditional drag laws requiring the flow and bottom stress to be collinear. In addition, the drag tensor field is updated periodically so …