Now showing items 297-316 of 779

• #### Damped Inexact Quasi-Newton Methods ﻿

(1981-12)
The inexact quasi-Newton methods are very attractive methods for large scale optimization since they require only an approximate solution of the linear system of equations for each iteration. To achieve global convergence ...
• #### Decentralized Jointly Sparse Optimization by Reweighted Lq Minimization ﻿

(2012-02)
A set of vectors (or signals) are jointly sparse if their nonzero entries are commonly supported on a small subset of locations. Consider a network of agents which collaborative recover a set of joint sparse vectors. This ...
• #### Deflated Krylov Subspace Methods for Nearly Singular Linear Systems ﻿

(1987-02)
This paper concerns the use of Krylov subspace methods for the solution of nearly singular nonsymmetric linear systems. We show that the Incomplete Orthogonalization Methods (IOM) in conjunction with certain deflation ...
• #### Deflation Techniques for an Implicitly Restarted Arnoldi Iteration ﻿

(1994-09)
A deflation procedure is introduced that is designed to improve convergence of an implicitly restarted Arnoldi iteration for computing a few eigenvalues of a large matrix. As the iteration progresses the Ritz value ...
• #### 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 low-rank approximate decomposition of the form ...
• #### Derivatives By-Address for Fortran 77 ﻿

(2006-12)
FIXME. Automatic differentiation tools use 1 of 2 strategies to access derivative values. These strategies are: By-address, By-name. The by-address method is typically implemented by introducing structured types for each ...
• #### Design Against Resonance ﻿

(1993-04)
A method for maximizing the distance from the spectrum of an analytic, symmetric matrix with distinct eigenvalues from a given frequency is proposed. The method models the classical approach from optimization of finding ...
• #### Design and Implementation of whirl2xaif and xaif2whirl ﻿

(2003-11)
In order to connect the Open64 Fortran front end to the xaifbooster differentiation engine, we needed to develop bridging tools to translate between Open64 intermediate representation language whirl and xaifbooster ...
• #### Designing and Analyzing Computational Experiments for Global Optimization ﻿

(2000-07)
We consider a variety of issues that arise when designing and analyzing computational experiments for global optimization. We describe a probability model for objective functions and a method for generating pseudorandom ...
• #### Detecting Periodic Components in a White Gaussian Time Series ﻿

(1986-10)
A family of tests for periodic components in a white Gaussian series is proposed. The test is based on a statistic which is proportional to the ratio of the maximum periodogram to the trimmed mean of the periodograms. The ...
• #### Detection and Imaging in Strongly Backscattering Randomly Layered Media ﻿

(2010-05)
Echoes from small reflectors buried in heavy clutter are weak and difficult to distinguish from the medium backscatter. Detection and imaging with sensor arrays in such media requires filtering out the unwanted backscatter ...
• #### Dimension Reduction for Unsteady Nonlinear Partial Differential Equations via Empirical Interpolation Methods ﻿

(2009-10)
This thesis evaluates and compares the efficiencies of techniques for constructing reduced-order models for finite difference (FD) and finite element (FE) discretized systems of unsteady nonlinear partial differential ...
• #### Direct Search Methods on Parallel Machines ﻿

(1990-09)
This paper describes an approach to constructing derivative-free parallel algorithms for unconstrained optimization which are easy to implement on parallel machines. A special feature of this approach is the ease with which ...
• #### Discontinuous Galerkin and Finite Difference Methods for the Acoustic Equations with Smooth Coefficients ﻿

(2015-06)
This thesis analyzes the computational efficiency of two types of numerical methods: finite difference (FD) and discontinuous Galerkin (DG) methods, in the context of 2D acoustic equations in pressure-velocity form with ...
• #### Discontinuous Galerkin Time Domain Methods for Acoustics and Comparison with Finite Difference Time Domain Methods ﻿

(2010-03)
This thesis describes an implementation of the discontinuous Galerkin finite element time domain (DGTD) method on unstructured meshes to solve acoustic wave equations in heterogeneous media. In oil industry people use ...
• #### Discrete Empirical Interpolation for Nonlinear Model Reduction ﻿

(2009-03)
A dimension reduction method called Discrete Empirical Interpolation (DEIM) is proposed and shown to dramatically reduce the computational complexity of the popular Proper Orthogonal Decomposition (POD) method for constructing ...
• #### Discretization of Multipole Sources in a Finite Difference Setting for Wave Propagation Problems ﻿

(2018-06-20)
Seismic sources are commonly idealized as point-sources due to their small spatial extent relative to seismic wavelengths. The acoustic isotropic point-radiator is inadequate as a model of seismic wave generation for seismic ...
• #### Distance Matrix Completion by Numerical Optimization ﻿

(1995-10)
Consider the problem of determining whether or not a partial dissimilarity matrix can be completed to a Euclidean distance matrix. The dimension of the distance matrix may be restricted and the known dissimilarities may ...
• #### Domain Decomposition Algorithms for Linear Hyperbolic Equations ﻿

(1987-08)
The use of parallel computers for solving partial differential equations is important in areas such as fluid dynamics, reservoir simulation, and structural analysis, where many of the problems of interest cannot be solved ...
• #### Domain Decomposition and Mixed Finite Element Methods for Elliptic Problems ﻿

(1987-05)
In this paper we describe the numerical solution of elliptic problems with nonconstant coefficients by domain decomposition methods based on a mixed formulation and mixed finite element approximations. Two families of ...