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- Guillaume Bal, Wenjia Jing
- 2010

We consider the problem of the random fluctuations in the solutions to elliptic PDEs with highly oscillatory random coefficients. In our setting, as the correlation length of the fluctuations tends to zero, the heterogeneous solution converges to a deterministic solution obtained by averaging. When the Green’s function to the unperturbed operator is… (More)

- Guillaume Bal, Wenjia Jing
- 2009

We consider the theory of correctors to homogenization in stationary transport equations with rapidly oscillating, random coefficients. Let ε 1 be the ratio of the correlation length in the random medium to the overall distance of propagation. As ε ↓ 0, we show that the heterogeneous transport solution is well-approximated by a homogeneous transport… (More)

- Guillaume Bal, Wenjia Jing
- Multiscale Modeling & Simulation
- 2011

Abstract. We analyze the random fluctuations of several multi-scale algorithms such as the multi-scale finite element method (MsFEM) and the finite element heterogeneous multi-scale method (HMM), that have been developed to solve partial differential equations with highly heterogeneous coefficients. Such multi-scale algorithms are often shown to correctly… (More)

- Habib Ammari, Thomas Boulier, Josselin Garnier, Wenjia Jing, Hyeonbae Kang, Han Wang
- Foundations of Computational Mathematics
- 2014

The aim of this paper is to provide a fast and efficient procedure for (real-time) target identification in imaging based on matching on a dictionary of precomputed generalized polarization tensors (GPTs). The approach is based on some important properties of the GPTs and new invariants. A new shape representation is given and numerically tested in the… (More)

- Guillaume Bal, Josselin Garnier, Yu Gu, Wenjia Jing
- Asymptotic Analysis
- 2012

We consider an elliptic pseudo-differential equation with a highly oscillating linear potential modeled as a stationary ergodic random field. The random field is a function composed with a centered long-range correlated Gaussian process. In the limiting of vanishing correlation length, the heterogeneous solution converges to a deterministic solution… (More)

We consider the optimization approach to the acousto-electric imaging problem. Assuming that the electric conductivity distribution is a small perturbation of a constant, we investigate the least square estimate analytically using (multiple) Fourier series, and confirm the widely observed fact that acousto-electric imaging has high resolution and is… (More)

- Habib Ammari, Elie Bretin, Josselin Garnier, Wenjia Jing, Hyeonbae Kang, Abdul Wahab
- SIAM J. Imaging Sciences
- 2013

The focus of this work is on rigorous mathematical analysis of the topological derivative based detection algorithms for the localization of an elastic inclusion of vanishing characteristic size. A filtered quadratic misfit is considered and the performance of the topological derivative imaging functional resulting therefrom is analyzed. Our analysis… (More)

- Habib Ammari, Josselin Garnier, Wenjia Jing
- Multiscale Modeling & Simulation
- 2013

We consider reflector imaging in a weakly random waveguide. We address the situation in which the source is farther from the reflector to be imaged than the energy equipartition distance, but the receiver array is closer to the reflector to be imaged than the energy equipartition distance. As a consequence, the reflector is illuminated by a partially… (More)

- Guillaume Bal, Wenjia Jing
- 2012

This paper analyzes the random fluctuations obtained by a heterogeneous multiscale first-order finite element method applied to solve elliptic equations with a random potential. Several multi-scale numerical algorithms have been shown to correctly capture the homogenized limit of solutions of elliptic equations with coefficients modeled as stationary and… (More)

We study the qualitative homogenization of second-order Hamilton–Jacobi equations in space-time stationary ergodic random environments. Assuming that the Hamiltonian is convex and superquadratic in the momentum variable (gradient), we establish a homogenization result and characterize the effective Hamiltonian for arbitrary (possibly degenerate) elliptic… (More)