Browsing Computational and Applied Mathematics by Issue Date
Now showing items 120 of 779

Discretization of Multipole Sources in a Finite Difference Setting for Wave Propagation Problems
(20180620)Seismic sources are commonly idealized as pointsources due to their small spatial extent relative to seismic wavelengths. The acoustic isotropic pointradiator is inadequate as a model of seismic wave generation for seismic ... 
Subset Selection and Feature Identification in the Electrocardiogram
(201804)Each feature in the electrocardiogram (ECG) corresponds to a different part of the cardiac cycle. Tracking changes in these features over long periods of time can offer insight regarding changes in a patient’s clinical ... 
Analysis of inverse boundary value problems for elastic waves
(201804)In seismology, people use waves generated by earthquakes, artificial explosions, or even “noises”, to detect the Earth’s interior structure. The waves traveling in rocks, which are the main components of Earth’s crust and ... 
Compositional heterogeneity near the base of the mantle transition zone beneath Hawaii
(2018)Global seismic discontinuities near 410 and 660 km depth in Earth’s mantle are expressions of solidstate phase transitions. These transitions modulate thermal and material fluxes across the mantle and variations in their ... 
Weight‐adjusted discontinuous Galerkin methods: Matrix‐valued weights and elastic wave propagation in heterogeneous media
(2018)Weight‐adjusted inner products are easily invertible approximations to weighted L2 inner products. These approximations can be paired with a discontinuous Galerkin (DG) discretization to produce a time‐domain method for ... 
An accelerated Poisson solver based on multidomain spectral discretization
(2018)This paper presents a numerical method for variable coefficient elliptic PDEs with mostly smooth solutions on two dimensional domains. The method works best for domains that can readily be mapped onto a rectangle, or a ... 
Reduced order modeling for timedependent optimization problems with initial value controls
(2018)This paper presents a new reduced order model (ROM) Hessian approximation for linearquadratic optimal control problems where the optimal control is the initial value. Such problems arise in parameter identification and ... 
An exact redatuming procedure for the inverse boundary value problem for the wave equation
(2018)Redatuming is a data processing technique to transform measurements recorded in one acquisition geometry to an analogous data set corresponding to another acquisition geometry, for which there are no recorded measurements. ... 
On discretely entropy conservative and entropy stable discontinuous Galerkin methods
(2018)High order methods based on diagonalnorm summation by parts operators can be shown to satisfy a discrete conservation or dissipation of entropy for nonlinear systems of hyperbolic PDEsﾠ[1],ﾠ[2]. These methods can also be ... 
Multipatch discontinuous Galerkin isogeometric analysis for wave propagation: Explicit timestepping and efficient mass matrix inversion
(2018)We present a class of spline finite element methods for timedomain wave propagation which are particularly amenable to explicit timestepping. The proposed methods utilize a discontinuous Galerkin discretization to enforce ... 
Topological Schemas of Memory Spaces
(2018)Hippocampal cognitive mapa neuronal representation of the spatial environmentis widely discussed in the computational neuroscience literature for decades. However, more recent studies point out that hippocampus plays a ... 
An Inverse Free Projected Gradient Descent Method for the Generalized Eigenvalue Problem
(201705)The generalized eigenvalue problem is a fundamental numerical linear algebra problem whose applications are wide ranging. For truly largescale problems, matrices themselves are often not directly accessible, but their ... 
Efficient estimation of coherent risk measures for riskaverse optimization problems governed by partial differential equations with random inputs
(201705)This thesis assesses and designs structureexploiting methods for the efficient estimation of risk measures of quantities of interest in the context of optimization of partial differential equations (PDEs) with random ... 
Graph Coloring, Zero Forcing, and Related Problems
(201705)This thesis investigates several problems related to classical and dynamic coloring of graphs, and enumeration of graph attributes. In the first part of the thesis, I present new efficient methods to compute the chromatic ... 
Novel Techniques for the ZeroForcing and pMedian Graph Location Problems
(201705)This thesis presents new methods for solving two graph location problems, the pMedian problem and the zeroforcing problem. For the pmedian problem, I present a branch decomposition based method that finds the best ... 
GPUAccelerated Discontinuous Galerkin Methods on Hybrid Meshes: Applications in Seismic Imaging
(201705)Seismic imaging is a geophysical technique assisting in the understanding of subsurface structure on a regional and global scale. With the development of computer technology, computationally intensive seismic algorithms ... 
Hermite Methods for the Simulation of Wave Propagation
(201705)Simulations of wave propagation play a crucial role in science and engineering. In applications of geophysics, they are the engine of many seismic imaging algorithms. For electrical engineers, they can be a useful tool for ... 
ProjectionBased Model Reduction in the Context of Optimization with Implicit PDE Constraints
(201705)I use reduced order models (ROMs) to substantially decrease the computational cost of Newton's method for largescale timedependent optimal control problems in settings where solving the implicit constraints and their ... 
Representation and Estimation of Seismic Sources via Multipoles
(201705)Accurate representation and estimation of seismic sources are essential to the seismic inversion problem. General sources can be approximated by a truncated series of multipoles depending on the source anisotropy. Most ... 
Bilevel Clique Interdiction and Related Problems
(201705)I introduce a formulation of the bilevel clique interdiction problem. Interdiction, a military term, describes the removal of enemy resources. The single level clique interdiction problem describes the attempt of an attacker ...