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 55 for “"Level-Set Method"”.
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A Fire Simulation Model for Heterogeneous Environments Using the Level Set Method
… complexity of fire behaviors. The raster-based method and the vector-based method are two major approaches that allow one to perform computerized fire spread simulation. In this thesis, we present a scheme we have developed that utilizes a level set method to build a fire spread simulation …
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An Implicit Level Set Model for Firespread
<p>The level set method is a mathematical and computational, technique for tracking a moving interface over time. It can naturally handle topological changes such as merging or breaking interfaces. Intrinsic geometric properties of the interface, such as curvature and normal direction, are easily …
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Development of level set methods for computing the semiclassical limit of Schrödinger equations with potentials
<p>In this thesis, several level set methods are developed and analyzed for computing multi-valued solutions to the semiclassical limits of Schroedinger equations. Both formulation and numerical results are obtained for level set method. Superposition is also proved via let set method setting. …
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Time-optimal path planning for sea-surface vehicles under the effects of strong currents and winds
A path-planning methodology that takes into account sea state fields, specifically wind forcing, is discussed and exemplified in this thesis. This general methodology has been explored by the Multidisciplinary Simulation, Estimation, and Assimilation Systems group (MSEAS) at MIT, however this is …
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Parallel algorithms applied to problems in two dimensional detonation shock dynamics
… for the shock surface. Full-LS-DSD2D is a full level set Detonation Shock Dynamics code in Fortran 77 written by Dr. John Bdzil specifically for this project. A level set function numerical algorithm which embeds the two-dimensional detonation front in a three-dimensional filed function, …
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Meshless methods: theory and application in 3D fracture modelling with level sets
… analysis of fracture is of vital importance yet methods for effetive 3D calculations are currently unsatisfactory. In this thesis, novel numerical techniques are developed which solve many of these problems. This thesis consists two major parts: firstly an investigation into the theory of …
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Shear Wall Layout Optimization in Coordination with Architectural Floor Plans
… of this research is to create an optimization method to reduce the material usage of shear wall layouts that operates quickly enough that it could be integrated into a design tool to mitigate the cyclical design process currently being used. This paper implements a variation on the level set …
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Fast Sweeping Methods for Steady State Hyperbolic Conservation Problems and Numerical Applications for Shape Optimization and Computational Cell Biology
… the capability to resolve shocks. Fast sweeping methods are efficient iterative numerical schemes originally designed for solving stationary Hamilton-Jacobi equations. Their efficiency relies on Gauss-Seidel type nonlinear iterations, and a finite number of sweeping directions. We generalize the …
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Topology optimisation for fluid flow and heat transfer applications
… to determine the merits and drawbacks of each method, extend the most suitable method to consider multi-material structures and to subsequently apply this method to design heat recovery structures subject to fluid convection. The two optimisation methods assessed were the density method and the …
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A Hybrid Variational-Level Set Approach to Handle Topological Changes
We present a method for allowing explicit, Lagrangian meshes to undergo topological changes in an automatic way. We employ a method for detecting when topological changes are imminent. When a change occurs, we use a level set method to guide the change of topology of the domain mesh. This is then …
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Fast Path Planning in Uncertain Environments: Theory and Experiments
… control path planning algorithm that is based on level-set methods. The hybrid method uses global or local level sets in the formulation of the receding horizon control problem. The decision to select a new level set is made based on certain matching conditions that guarantee the optimality of the …
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People Tracking Under Occlusion Using Gaussian Mixture Model and Fast Level Set Energy Minimization
… are matched to the models using a fast numerical level set method. Since each target is tracked with its blob's information, the system is capable of handling partial or full occlusion during tracking. Experimental results on a number of challenging sequences that were collected in …
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Energy-time optimal path planning in strong dynamic flows
… an exact partial differential equation-based methodology that predicts time-energy optimal paths for autonomous vehicles navigating in dynamic environments. The differential equations solve the multi-objective optimization problem of navigating a vehicle autonomously in a dynamic flow field to …
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Flow in thin regions bounded by structured and porous surfaces : applications to load bearings
… most engineered materials are textured at some level either deliberately to achieve some desired effect or produced by wear and friction of surfaces. This thesis analyses the effect of surface roughness and porosity on the load capacity of hydrodynamic bearings. The surface roughness is …
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Investigative Application of the Intrinsic Extended Finite Element Method for the Computational Characterization of Composite Materials
… independent intrinsic extended finite element method (IXFEM). The IXFEM employs a localized intrinsic enrichment strategy to treat arbitrary discontinuities defined through the level-set method separate from the problem domain discretization, i.e. the finite element (FE) mesh. A global domain …
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Numerical methods for solar tomography in the STEREO era
… parameters in the solar corona. We focus on methods for both global dynamic estimation of the coronal electron density and estimation of local transient phenomena, such as coronal mass ejections, from empirical observations acquired by instruments onboard the STEREO spacecraft. We present a …
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Detecting open surfaces in three dimensions
We present a novel level-set method for representing and detecting open surfaces embedded in three-dimensional image volumes. Open surfaces are two-dimensional manifolds with a one-dimensional boundary lying within a three-dimensional volume. Distinct portions of a closed surface can be modeled as …
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Time-optimal path planning in uncertain flow fields using stochastic dynamically orthogonal level set equations
… develop a rigorous and computationally efficient methodology to perform path-planning in uncertain flow fields. We obtain new stochastic Dynamically Orthogonal (DO) Level Set equations to account for uncertainty in the flow field. We first review existing path-planning work: time-optimal path …
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Multiscale Mathematical Modelling of Cancer Invasion
… we tested our modelling concept by applying a level-set method to a moving boundary problem. Later, a multi-scale mathematical model of cancer invasion was developed by coupling the urokinase plasminogen activation (uPA) system with a two-scale computational modelling technique. This approach …
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