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The wave equation is time-reversal invariant. The enclosure method using a Neumann data generated by this invariance is introduced. The method yields the minimum ball that is centered at a given arbitrary point and encloses an unknown…

Analysis of PDEs · Mathematics 2021-03-16 Masaru Ikehata

The aim of this chapter is to make a review of the recent results using the Enclosure Method on inverse obstacle problems governed by the wave equation and the Maxwell system in time domain. We also describe some of unsolved problems…

Analysis of PDEs · Mathematics 2015-12-16 Masaru Ikehata

The enclosure method was originally introduced for inverse problems of concerning non-destructive evaluation governed by elliptic equations. It was developed as one of useful approaches in inverse problems and applied for various equations.…

Analysis of PDEs · Mathematics 2021-03-30 Masaru Ikehata , Mishio Kawashita

A simple method for some class of inverse obstacle scattering problems is introduced. The observation data are given by a wave field measured on a known surface surrounding unknown obstacles over a finite time interval. The wave is…

Analysis of PDEs · Mathematics 2011-09-21 Masaru Ikehata

An inverse obstacle problem for the wave equation in a two layered medium is considered. It is assumed that the unknown obstacle is penetrable and embedded in the lower half-space. The wave as a solution of the wave equation is generated by…

Analysis of PDEs · Mathematics 2018-08-07 Masaru Ikehata , Mishio Kawashita

A mathematical method for through-wall imaging via wave phenomena in the time domain is introduced. The method makes use of a single reflected wave over a finite time interval and gives us a criterion whether a penetrable obstacle exists or…

Analysis of PDEs · Mathematics 2018-03-06 Masaru Ikehata

An inverse obstacle problem for the wave governed by the wave equation in a two layered medium is considered under the framework of the time domain enclosure method. The wave is generated by an initial data supported on a closed ball in the…

Analysis of PDEs · Mathematics 2018-07-09 Masaru Ikehata , Mishio Kawashita , Wakako Kawashita

The time domain enclosure method is one of analytical methods for inverse obstacle problems governed by partial differential equations in the time domain. This paper considers the case when the governing equation is given by the Maxwell…

Analysis of PDEs · Mathematics 2023-06-09 Masaru Ikehata

Now a final and maybe simplest formulation of the enclosure method applied to inverse obstacle problems governed by partial differential equations in a {\it spacial domain with an outer boundary} over a finite time interval is fixed. The…

Analysis of PDEs · Mathematics 2017-12-07 Masaru Ikehata

A simple idea of finding a domain that encloses an unknown discontinuity embedded in a body is introduced by considering an inverse boundary value problem for the heat equation. The idea gives a design of a special heat flux on the surface…

Analysis of PDEs · Mathematics 2021-03-09 Masaru Ikehata

In these lectures I give an introduction to the time-dependent approach to inverse scattering, that has been developed recently. The aim of this approach is to solve various inverse scattering problems with time-dependent methods that…

Mathematical Physics · Physics 2007-05-23 Ricardo Weder

More than ten years ago Ikehata discovered two mathematical methods for the purpose of extracting information about the location and shape of unknown discontinuity embedded in a known background medium from observation data. The methods are…

Analysis of PDEs · Mathematics 2011-09-21 Masaru Ikehata

The aim of this paper is to establish the framework of the enclosure method for some class of inverse problems whose governing equations are given by parabolic equations with discontinuous coefficients. The framework is given by considering…

Analysis of PDEs · Mathematics 2011-09-21 Masaru Ikehata

An inverse obstacle problem governed by the Stokes system in the time domain is considered. Two types of extraction formulae about the geometry of an unknown obstacle are given by using the most recent version of the time domain enclosure…

Analysis of PDEs · Mathematics 2025-08-25 Masaru Ikehata

This paper is concerned with reconstruction issue of inverse obstacle problems governed by partial differential equations and consists of two parts. (i) The first part considers the foundation of the probe and enclosure methods for an…

Analysis of PDEs · Mathematics 2022-07-11 Masaru Ikehata

Methodology is provided towards the solution of the minimum enclosing ball problem. This problem concerns the determination of the unique spherical surface of smallest radius enclosing a given bounded set in the d-dimensional Euclidean…

Computational Geometry · Computer Science 2024-10-16 Michael N. Vrahatis

In this paper, the inverse problem of the wave equation by the enclosure method for a medium with multiple types of cavities is discussed. In the case considered here, the sign of the indicator function of the enclosure method is not…

Analysis of PDEs · Mathematics 2024-02-21 Mishio Kawashita , Wakako Kawashita

We consider the time-harmonic elastic wave scattering from a general (possibly anisotropic) inhomogeneous medium with an embedded impenetrable obstacle. We show that the impenetrable obstacle can be effectively approximated by an isotropic…

Analysis of PDEs · Mathematics 2021-02-19 Zhengjian Bai , Huaian Diao , Hongyu Liu , Qingle Meng

This paper focuses on the time-harmonic electromagnetic (EM) scattering problem in a general medium which may possess a nontrivial topological structure. We model this by an inhomogeneous and possibly anisotropic medium with embedded…

Analysis of PDEs · Mathematics 2024-08-14 Huaian Diao , Hongyu Liu , Qingle Meng , Li Wang

In this paper, a time domain enclosure method for an inverse obstacle scattering problem of electromagnetic wave is introduced. The wave as a solution of Maxwell's equations is generated by an applied volumetric current having an {\it…

Analysis of PDEs · Mathematics 2016-07-22 Masaru Ikehata
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