Browsing by Issue Date
Now showing items 120 of 888

Sensitivity study of boreholetosurface and crosswell electromagnetic measurements acquired with energized steel casing to water displacement in hydrocarbonbearing layers
(Geophysics, 20081231)We study the theoretical response of electromagnetically energized steel casing in the presence of subsurface variations of electrical resistivity. Casing is energized with a finitesize solenoid antenna located along the ... 
Energynormbased and goaloriented automatic hp adaptivity for electromagnetics: Application to waveguide Discontinuities
(IEEE Transactions on Microwave Theory and Techniques, 20081231)The finiteelement method (FEM) enables the use of adapted meshes. The simultaneous combination of h (local variations in element size) and p (local variations in the polynomial order of approximation) refinements, i.e., ... 
Identification of the class of initial data for the insensitizing control of the heat equation
(Communications on Pure and Applied Analysis, 20091231)This paper is devoted to analyze the class of initial data that can be insensitized for the heat equation. This issue has been extensively addressed in the literature both in the case of complete and approximate insensitization ... 
Time discrete wave equations: Boundary observability and control
(Discrete and Continuous Dynamical Systems, 20091231)In this paper we study the exact boundary controllability of a trapezoidal time discrete wave equation in a bounded domain. We prove that the projection of the solution in an appropriate filtered space is exactly controllable ... 
Convergence of a twogrid algorithm for the control of the wave equation
(Journal of the European Mathematical Society, 20091231)We analyze the problem of boundary observability of the finitedifference space semidiscretizations of the 2d wave equation in the square.We prove the uniform (with respect to the meshsize) boundary observability for the ... 
Numerical dispersive schemes for the nonlinear Schrödinger equation
(SIAM Journal on Numerical Analysis, 20091231)We consider semidiscrete approximation schemes for the linear Schrödinger equation and analyze whether the classical dispersive properties of the continuous model hold for these approximations. For the conservative finite ... 
Uniformly exponentially stable approximations for a class of damped systems
(Journal des Mathematiques Pures et Appliquees, 20091231)We consider time semidiscrete approximations of a class of exponentially stable infinitedimensional systems modeling, for instance, damped vibrations. It has recently been proved that for time semidiscrete systems, due ... 
Homogenization of fiber reinforced brittle materials: The extremal cases
(SIAM Journal on Mathematical Analysis, 20091231)We analyze the behavior of a fragile material reinforced by a reticulated elastic unbreakable structure in the case of antiplane shear. The microscopic geometry of this material is described by means of two small parameters: ... 
Minimization of length and curvature on planar curves
(Proceedings of the IEEE Conference on Decision and Control, 20091231)In this paper we consider the problem of reconstructing a curve that is partially hidden or corrupted by minimizing the functional ∫ √1+K 2 ds, depending both on length and curvature K. We fix starting and ending points ... 
Stabilization of the wave equation on 1D networks
(SIAM Journal on Control and Optimization, 20091231)In this paper we study the stabilization of the wa ve equation on general 1d networks. For that, we transfer known observability results in the context of control problems of conservative systems (see [R. Dáger and E. ... 
Some controllability results for the 2D Kolmogorov equation
(Annales de l'Institut Henri Poincare (C) Analyse Non Lineaire, 20091231)In this article, we prove the null controllability of the 2D Kolmogorov equation both in the whole space and in the square. The control is a source term in the righthand side of the equation, located on a subdomain, that ... 
Hardy inequalities, observability, and control for the wave and schrödinger equations with singular potentials
(SIAM Journal on Mathematical Analysis, 20091231)We address the question of exact controllability of the wave and Schrodinger equa\tions perturbed by a singular inversesquare potential. Exact boundary controllability is proved in the range of subcritical coefficients ... 
Asymptotic stability of the stationary solution to an initial boundary value problem for the Mullins equation of fourth order
(Journal of Mathematical Physics, 20091231)In the present article we first study the existence of the stationary solution to an initial boundary value problem for the Mullins equation of fourth order, which was proposed by Mullins ["Twodimensional motion of idealized ... 
On the Gittins index in the M/G/1 queue
(Queueing Systems, 20091231)For an M/G/1 queue with the objective of minimizing the mean number of jobs in the system, the Gittins index rule is known to be optimal among the set of nonanticipating policies. We develop properties of the Gittins ... 
Optimal policy for multiclass scheduling in a single server queue
(21st International Teletraffic Congress, ITC 21: Traffic and Performance Issues in Networks of the Future  Final Programme, 20091231)In this paper we apply the Gittins optimality result to characterize the optimal scheduling discipline in a multiclass M/G/1 queue. We apply the general result to several cases of practical interest where the service time ... 
Heavytraffic analysis of the M/PH/1 Discriminatory Processor Sharing queue with phasedependent weights
(Performance Evaluation Review, 20091231)We analyze a generalization of the Discriminatory Processor Sharing (DPS) queue in a heavytraffic setting. Customers present in the system are served simultaneously at rates controlled by a vector of weights. We assume ... 
2D euler shape design on nonregular flows using adjoint rankinehugoniot relations
(AIAA Journal, 20091231)Optimal aerodynamic shape design aims to find the minimum of a functional that describes an aerodynamic property, by controlling the partial differential equation modeling the dynamics of the flow that surrounds an aircraft, ... 
Asymptotic stability of rarefaction wave for the navierstokes equations for a compressible fluid in the half space
(Archive for Rational Mechanics and Analysis, 20091231)This paper is concerned with the asymptotic stability towards a rarefaction wave of the solution to an outflow problem for the NavierStokes equations in a compressible fluid in the Eulerian coordinate in the half space. ... 
Simulation of DC duallaterolog measurements in complex formations: A Fourierseries approach with nonorthogonal coordinates and selfadapting finite elements
(Geophysics, 20091231)Dual laterolog (DLL) makes use of a galvanic conduction principle to focus electrical currents into rock formations, thereby minimizing shoulder and borehole effects in the measurement of formation resistivity. The tool ... 
Performance of a multifrontal parallel direct solver for hpfinite element method
(Proceedings of the IASTED International Conference on Advances in Computer Science and Engineering, ACSE 2009, 20091231)In this paper we present the performance of our parallel multifrontal direct solver when applied to solve linear systems of equations resulting from discretizations of a hp Finite Element Method (hpFEM). The hpFEM ...