Browsing Scholarly Works, Department of Mathematics by Author "Virginia Tech"
Now showing items 1-20 of 123
-
A comparison of viscoelastic stress wakes for two-dimensional and three-dimensional Newtonian drop deformations in a viscoelastic matrix under shear
(American Institute of Physics, 2009-07)A recent experimental study of a Newtonian drop suspended in a viscoelastic matrix undergoing simple shear displays a transient overshoot in drop deformation which is qualitatively similar to two-dimensional (2D) numerical ... -
A finite element splitting extrapolation for second order hyperbolic equations
(Siam Publications, 2009)Splitting extrapolation is an efficient technique for solving large scale scientific and engineering problems in parallel. This article discusses a finite element splitting extrapolation for second order hyperbolic equations ... -
A general convergence analysis of some Newton-type methods for nonlinear inverse problems
(Siam Publications, 2011)We consider the methods x(n+1)(delta) - x(n)(delta) - g(alpha n) (F'(x(n)(delta))* F'(x(n)(delta)))F'(x(n)(delta))*(F(x(n)(delta)) - y(delta)) for solving nonlinear ill-posed inverse problems F(x) = y using the only available ... -
A hybrid collocation method for volterra integral equations with weakly singular kernels
(Siam Publications, 2003)The commonly used graded piecewise polynomial collocation method for weakly singular Volterra integral equations may cause serious round-off error problems due to its use of extremely nonuniform partitions and the sensitivity ... -
A multiple-scales space-time analysis of a randomly perturbed one-dimensional wave equation
(AIP Publishing, 1977-10)An initial value problem for one_dimensional wave propagation is considered; the medium is assumed to be randomly perturbed as a function of both space and time. The stochastic perturbation theory of Papanicolaou and Keller ... -
A note on the switching adiabatic theorem
(AIP Publishing, 2012-10)We derive a nearly optimal upper bound on the running time in the adiabatic theorem for a switching family of Hamiltonians. We assume the switching Hamiltonian is in the Gevrey class G(alpha) as a function of time, and we ... -
A numerical study of periodic disturbances on two-layer Couette flaw
(AIP Publishing, 1998-12)The flow of two viscous liquids is investigated numerically with a volume of fluid scheme. The scheme incorporates a semi-implicit Stokes solver to enable computations at low Reynolds numbers, and a second-order velocity ... -
A regularized Gauss-Newton trust region approach to imaging in diffuse optical tomography
(Siam Publications, 2011)We present a new algorithm for the solution of nonlinear least squares problems arising from parameterized imaging problems with diffuse optical tomographic data [D. Boas et al., IEEE Signal Process. Mag., 18 (2001), pp. ... -
A state space error estimate for pod-deim nonlinear model reduction
(Siam Publications, 2012)This paper derives state space error bounds for the solutions of reduced systems constructed using proper orthogonal decomposition (POD) together with the discrete empirical interpolation method (DEIM) recently developed ... -
A uniqueness result for p-Monotone viscosity solutions of Hamilton-Jacobi equations in bounded domains
(Siam Publications, 2009)We consider a class of Hamilton-Jacobi equations H(x, Du(x)) - 0 with no u-dependence and with continuity properties consistent with recent applications in queueing theory. Continuous viscosity solutions are considered in ... -
A volume-of-fluid formulation for the study of co-flowing fluids governed by the Hele-Shaw equations
(American Institute of Physics, 2013-08)We present a computational framework to address the flow of two immiscible viscous liquids which co-flow into a shallow rectangular container at one side, and flow out into a holding container at the opposite side. Assumptions ... -
Abacus proofs of Schur function identities
(Siam Publications, 2010)This article uses combinatorial objects called labeled abaci to give direct combinatorial proofs of many familiar facts about Schur polynomials. We use abaci to prove the Pieri rules, the Littlewood-Richardson rule, the ... -
An effective method for parameter estimation with pde constraints with multiple right-hand sides
(Siam Publications, 2012)Often, parameter estimation problems of parameter-dependent PDEs involve multiple right-hand sides. The computational cost and memory requirements of such problems increase linearly with the number of right-hand sides. For ... -
An elementary nonlinear beam theory with finite buckling deformation properties
(Siam Publications, 2002-04)A simple nonlinear beam model is derived from basic principles. The assumption upon which the derivation is based is that axial motions are of second order compared with transverse motions of the beam. The existence of ... -
Analysis and approximation of the velocity tracking problem for Navier-Stokes flows with distributed control
(Siam Publications, 2000-05)We consider the mathematical formulation, analysis, and the numerical solution of a time-dependent optimal control problem associated with the tracking of the velocity of a Navier-Stokes ow in a bounded two-dimensional ... -
Analytic theory for the selection of a two-dimensional needle crystal at arbitrary Péclet number
(American Physical Society, 1989-10)An accurate analytic theory is presented for the velocity selection of a two-dimensional needle crystal for arbitrary Péclet number for small values of the surface-tension parameter. The velocity selection is caused by the ... -
Analytical solutions of model equations for two phase gas mixtures: Transverse velocity perturbations
(AIP Publishing, 1984)Model equations for a dilute binary gas system are derived, using a linear BGK scheme. Complete analytical solutions for the stationary half_space problem are obtained for transverse velocity perturbations. The method of ... -
Anomalous decay of a prepared state due to non-Ohmic coupling to the continuum
(American Physical Society, 2010-03)We study the decay of a prepared state E(0) into a continuum {E(k)} in the case of non-Ohmic models. This means that the coupling is |V(k),(0)| proportional to |E(k)-E(0)|(s-1) with s not equal 1. We find that irrespective ... -
Anomaly meltdown
(AIP Publishing, 1991-08)It is shown that at nonzero temperature it is possible that anomalies in representations of symmetry groups and gauge groups, present at zero temperature, disappear. Several examples are given. Thus the idea that anomalies ... -
Asymptotic-behavior of Jost functions near resonance points for Wigner-Vonneumann type potentials
(AIP Publishing, 1991-01)In this work are considered radial Schrodinger operators - psi" + V(r)-psi = E-psi, where V(r) = a sin br/r + W(r) with W(r) bounded, W(r) = O(r-2) at infinity (a,b real). The asymptotic behavior of the Jost function and ...
