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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 ... 
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. ... 
Mapping Mantle Transition Zone Discontinuities Beneath the Central Pacific With Array Processing ofﾠSSﾠPrecursors
(2017)We image mantle transition zone (MTZ) discontinuities beneath the Central Pacific using ~120,000 broadband SS waveforms. With a wave packet‐based array processing technique (curvelet transform), we improve the signal‐to‐noise ... 
Landau Collision Integral Solver with Adaptive Mesh Refinement on Emerging Architectures
(2017)The Landau collision integral is an accurate model for the smallangle dominated Coulomb collisions in fusion plasmas. We investigate a high order accurate, fully conservative, finite element discretization of the nonlinear ... 
A discrepancybased penalty method for extended waveform inversion
(2017)Extended waveform inversion globalizes the convergence of seismic waveform inversion by adding nonphysical degrees of freedom to the model, thus permitting it to fit the data well throughout the inversion process. These ... 
A DistributedMemory Randomized Structured Multifrontal Method for Sparse Direct Solutions
(2017)We design a distributedmemory randomized structured multifrontal solver for large sparse matrices. Two layers of hierarchical tree parallelism are used. A sequence of innovative parallel methods are developed for randomized ... 
An alternating direction and projection algorithm for structureenforced matrix factorization
(2017)Structureenforced matrix factorization (SeMF) represents a large class of mathematical models appearing in various forms of principal component analysis, sparse coding, dictionary learning and other machine learning ... 
Angola Cameia Development CasingSettlement Calculations
(2017)The amount of axial settlement of casings supported by regions of axial elastic foundations is computed. The differential equation of axial equilibrium, including the foundation stiffnesses, is solved by use of cubic axial ... 
Fullwaveform inversion via sourcereceiver extension
(2017)Fullwaveform inversion produces highly resolved images of the subsurface and quantitative estimation of seismic wave velocity, provided that its initial model is kinematically accurate at the longest data wavelengths. If ... 
Impact of Optimized Breastfeeding on the Costs of Necrotizing Enterocolitis in Extremely Low Birthweight Infants
(2016)Objective: To estimate risk of necrotizing enterocolitis (NEC) for extremely low birth weight (ELBW) infants as a function of preterm formula (PF) and maternal milk intake and calculate the impact of suboptimal feeding on ... 
Shape Optimization of Shell Structure Acoustics
(2017)This paper provides a rigorous framework for the numerical solution of shape optimization problems in shell structure acoustics using a referencedomain approach. The structure is modeled with Naghdi shell equations, fully ... 
A Branch Decomposition Algorithm for the pMedian Problem
(2017)In this paper, we use a branch decomposition technique to improve approximations to the pmedian problem. Starting from a support graph produced either by a combination of heuristics or by linear programming, we use dynamic ... 
ResidualBased Adaptivity and PWDG Methods for the Helmholtz Equation
(2015)We present a study of two residual a posteriori error indicators for the plane wave discontinuous Galerkin (PWDG) method for the Helmholtz equation. In particular, we study the $h$version of PWDG in which the number of ... 
A Comparison of High Order Interpolation Nodes for the Pyramid
(2015)The use of pyramid elements is crucial to the construction of efficient hexdominant meshes [M. Bergot, G. Cohen, and M. Duruflé, J. Sci. Comput., 42 (2010), pp. 345381]. For conforming nodal finite element methods with ... 
An Efficient GaussNewton Algorithm for Symmetric LowRank Product Matrix Approximations
(2015)We derive and study a GaussNewton method for computing a symmetric lowrank product $XX^{{T}}$, where $X \in{\mathbb{R}}^{n\times k}$ for $k<n$, that is the closest to a given symmetric matrix $A \in{\mathbb{R}}^{n\times ... 
Optimal Convergence Rates Results for Linear Inverse Problems in Hilbert Spaces
(2016)In this article, we prove optimal convergence rates results for regularization methods for solving linear illposed operator equations in Hilbert spaces. The results generalizes existing convergence rates results on ... 
A DEIM Induced CUR Factorization
(2016)We derive a CUR approximate matrix factorization based on the discrete empirical interpolation method (DEIM). For a given matrix ${\bf A}$, such a factorization provides a lowrank approximate decomposition of the form ... 
Inverse Boundary Value Problem For The Helmholtz Equation: Quantitative Conditional Lipschitz Stability Estimates
(2016)We study the inverse boundary value problem for the Helmholtz equation using the DirichlettoNeumann map at selected frequencies as the data. A conditional Lipschitz stability estimate for the inverse problem holds in the ... 
An approximate inverse to the extended Born modeling operator
(2015)Given a correct (dataconsistent) velocity model, reverse time migration (RTM) correctly positions reflectors but generally with incorrect amplitudes and wavelets. Iterative leastsquares migration (LSM) corrects the ...