Browsing Scholarly Works, Department of Mathematics by Author "Virginia Tech"
Now showing items 120 of 123

A comparison of viscoelastic stress wakes for twodimensional and threedimensional Newtonian drop deformations in a viscoelastic matrix under shear
Afkhami, S.; Yue, P.; Renardy, Y. (American Institute of Physics, 200907)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 twodimensional (2D) numerical ... 
A finite element splitting extrapolation for second order hyperbolic equations
He, X. M.; Lu, T. (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 Newtontype methods for nonlinear inverse problems
Jin, Q. N. (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 illposed inverse problems F(x) = y using the only available ... 
A hybrid collocation method for volterra integral equations with weakly singular kernels
Cao, Y. Z.; Herdman, T.; Xu, Y. H. (Siam Publications, 2003)The commonly used graded piecewise polynomial collocation method for weakly singular Volterra integral equations may cause serious roundoff error problems due to its use of extremely nonuniform partitions and the sensitivity ... 
A multiplescales spacetime analysis of a randomly perturbed onedimensional wave equation
Kohler, Werner E. (AIP Publishing, 197710)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
Elgart, Alexander; Hagedorn, George A. (AIP Publishing, 201210)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 twolayer Couette flaw
Li, J.; Renardy, Yuriko Y.; Renardy, Michael J. (AIP Publishing, 199812)The flow of two viscous liquids is investigated numerically with a volume of fluid scheme. The scheme incorporates a semiimplicit Stokes solver to enable computations at low Reynolds numbers, and a secondorder velocity ... 
A regularized GaussNewton trust region approach to imaging in diffuse optical tomography
de Sturler, E.; Kilmer, M. E. (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 poddeim nonlinear model reduction
Chaturantabut, S.; Sorensen, D. C. (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 pMonotone viscosity solutions of HamiltonJacobi equations in bounded domains
Day, Martin V. (Siam Publications, 2009)We consider a class of HamiltonJacobi equations H(x, Du(x))  0 with no udependence and with continuity properties consistent with recent applications in queueing theory. Continuous viscosity solutions are considered in ... 
A volumeoffluid formulation for the study of coflowing fluids governed by the HeleShaw equations
Afkhami, S.; Renardy, Y. (American Institute of Physics, 201308)We present a computational framework to address the flow of two immiscible viscous liquids which coflow 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
Loehr, N. A. (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 LittlewoodRichardson rule, the ... 
An effective method for parameter estimation with pde constraints with multiple righthand sides
Haber, Eldad; Chung, Matthias; Herrmann, Felix (Siam Publications, 2012)Often, parameter estimation problems of parameterdependent PDEs involve multiple righthand sides. The computational cost and memory requirements of such problems increase linearly with the number of righthand sides. For ... 
An elementary nonlinear beam theory with finite buckling deformation properties
Russell, David L.; White, Luther W. (Siam Publications, 200204)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 NavierStokes flows with distributed control
Gunzburger, M. D.; Manservisi, S. (Siam Publications, 200005)We consider the mathematical formulation, analysis, and the numerical solution of a timedependent optimal control problem associated with the tracking of the velocity of a NavierStokes ow in a bounded twodimensional ... 
Analytic theory for the selection of a twodimensional needle crystal at arbitrary Péclet number
Tanveer, S. (American Physical Society, 198910)An accurate analytic theory is presented for the velocity selection of a twodimensional needle crystal for arbitrary Péclet number for small values of the surfacetension parameter. The velocity selection is caused by the ... 
Analytical solutions of model equations for two phase gas mixtures: Transverse velocity perturbations
Cavalier, J. F.; Greenberg, W. (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 nonOhmic coupling to the continuum
Sela, I.; Aisenberg, J.; Kottos, T.; Elgart, A.; Cohen, D. (American Physical Society, 201003)We study the decay of a prepared state E(0) into a continuum {E(k)} in the case of nonOhmic models. This means that the coupling is V(k),(0) proportional to E(k)E(0)(s1) with s not equal 1. We find that irrespective ... 
Anomaly meltdown
Gajdzinski, C.; Streater, R. F. (AIP Publishing, 199108)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 ... 
Asymptoticbehavior of Jost functions near resonance points for WignerVonneumann type potentials
Klaus, M. (AIP Publishing, 199101)In this work are considered radial Schrodinger operators  psi" + V(r)psi = Epsi, where V(r) = a sin br/r + W(r) with W(r) bounded, W(r) = O(r2) at infinity (a,b real). The asymptotic behavior of the Jost function and ...