# American Institute of Mathematical Sciences

April  2022, 16(2): 417-450. doi: 10.3934/ipi.2021056

## Small defects reconstruction in waveguides from multifrequency one-side scattering data

 1 Institut Fourier, Université Grenoble Alpes, France 2 Institut Camille Jordan, École Centrale Lyon, France

* Corresponding author: Angèle Niclas

Received  January 2021 Revised  June 2021 Published  April 2022 Early access  September 2021

Localization and reconstruction of small defects in acoustic or electromagnetic waveguides is of crucial interest in nondestructive evaluation of structures. The aim of this work is to present a new multi-frequency inversion method to reconstruct small defects in a 2D waveguide. Given one-side multi-frequency wave field measurements of propagating modes, we use a Born approximation to provide a $\text{L}^2$-stable reconstruction of three types of defects: a local perturbation inside the waveguide, a bending of the waveguide, and a localized defect in the geometry of the waveguide. This method is based on a mode-by-mode spacial Fourier inversion from the available partial data in the Fourier domain. Indeed, in the available data, some high and low spatial frequency information on the defect are missing. We overcome this issue using both a compact support hypothesis and a minimal smoothness hypothesis on the defects. We also provide a suitable numerical method for efficient reconstruction of such defects and we discuss its applications and limits.

Citation: Éric Bonnetier, Angèle Niclas, Laurent Seppecher, Grégory Vial. Small defects reconstruction in waveguides from multifrequency one-side scattering data. Inverse Problems and Imaging, 2022, 16 (2) : 417-450. doi: 10.3934/ipi.2021056
##### References:
 [1] L. Abrahamsson, Orthogonal grid generation for two-dimensional ducts, J. Comput. Appl. Math., 34 (1991), 305-314.  doi: 10.1016/0377-0427(91)90091-W. [2] L. Abrahamsson and H. O. Kreiss, Numerical solution of the coupled mode equations in duct acoustics, J. Comput. Phy., 111 (1994), 1-14.  doi: 10.1006/jcph.1994.1038. [3] S. Acosta, S. Chow, J. Taylor and V. Villamizar, On the multi-frequency inverse source problem in heterogeneous media, Inverse Problems, 28 (2012), 075013. doi: 10.1088/0266-5611/28/7/075013. [4] H. Ammari, E. Iakovleva and H. Kang, Reconstruction of a small inclusion in a two-dimensional open waveguide, SIAM J. Appl. Math., 65 (2005), 2107-2127.  doi: 10.1137/040615389. [5] G. Bao and P. Li, Inverse medium scattering problems for electromagnetic waves, SIAM J. Appl. Math., 65 (2005), 2049-2066.  doi: 10.1137/040607435. [6] G. Bao and F. Triki, Reconstruction of a defect in an open waveguide, Sci. China Math., 56 (2013), 2539-2548.  doi: 10.1007/s11425-013-4696-8. [7] G. Bao and F. Triki, Stability for the multifrequency inverse medium problem, J. Differential Equations, 269 (2020), 7106-7128.  doi: 10.1016/j.jde.2020.05.021. [8] J. P. Berenger, A perfectly matched layer for the absorption of electromagnetic waves, J. Comput. Phys., 114 (1994), 185-200.  doi: 10.1006/jcph.1994.1159. [9] L. Bourgeois and S. Fliss, On the identification of defects in a periodic waveguide from far field data, Inverse Problems, 30 (2014), 095004. doi: 10.1088/0266-5611/30/9/095004. [10] L. Bourgeois and E. Lunéville, The linear sampling method in a waveguide: A modal formulation, Inverse Problems, 24 (2008), 015018. doi: 10.1088/0266-5611/24/1/015018. [11] D. Colton and A. Kirsch, A simple method for solving inverse scattering problems in the resonance region, Inverse Problems, 12 (1996), 383-393.  doi: 10.1088/0266-5611/12/4/003. [12] D. Colton and R. Kress, Inverse Acoustic and Electromagnetic Scattering Theory, Applied Mathematical Sciences, Springer-Verlag, Berlin, 1992. doi: 10.1007/978-3-662-02835-3. [13] S. Dediu and J. R. McLaughlin, Recovering inhomogeneities in a waveguide using eigensystem decomposition, Inverse Problems, 22 (2006), 1227-1246.  doi: 10.1088/0266-5611/22/4/007. [14] A. S. B.-B. Dhia, L. Chesnel and S. A. Nazarov, Perfect transmission invisibility for waveguides with sound hard walls, J. Math. Pures Appl., 111 (2018), 79-105.  doi: 10.1016/j.matpur.2017.07.020. [15] H. Dym and H. P. McKean, Fourier Series and Integrals, Academic Press New York, 1972. [16] P. Grisvard, Elliptic Problems in Nonsmooth Domains, Society for Industrial and Applied Mathematics, 2011. doi: 10.1137/1.9781611972030.ch1. [17] M. Isaev and R. G. Novikov, Hölder-logarithmic stability in Fourier synthesis, Inverse Problems, 36 (2020), 125003. doi: 10.1088/1361-6420/abb5df. [18] V. Isakov and S. Lu, Increasing stability in the inverse source problem with attenuation and many frequencies, SIAM J. Appl. Math., 78 (2018), 1-18.  doi: 10.1137/17M1112704. [19] M. Kharrat, O. Bareille, W. Zhou and M. Ichchou, Nondestructive assessment of plastic elbows using torsional waves: Numerical and experimental investigations, Journal of Nondestructive Evaluation, 35 (2016), 1-14.  doi: 10.1007/s10921-015-0324-6. [20] M. Kharrat, M. N. Ichchou, O. Bareille and W. Zhou, Pipeline inspection using a torsional guided-waves inspection system. part 1: Defect identification, International Journal of Applied Mechanics, 6 (2014). doi: 10.1142/S1758825114500343. [21] Y. Y. Lu, Exact one-way methods for acoustic waveguides, Math. Comput. Simulation, 50 (1999), 377-391.  doi: 10.1016/S0378-4754(99)00111-1. [22] W. McLean, Strongly Elliptic Systems and Boundary Integral Equations, Cambridge University Press, 2000. [23] M. Sini and N. T. Thanh, Inverse acoustic obstacle scattering problems using multifrequency measurements, Inverse Probl. Imaging, 6 (2012), 749-773.  doi: 10.3934/ipi.2012.6.749. [24] J. Todd, The condition of the finite segment of the Hilbert matrix, National Bureau of Standarts, Applied Mathematics Series, (1954), 109–119.

show all references

##### References:
 [1] L. Abrahamsson, Orthogonal grid generation for two-dimensional ducts, J. Comput. Appl. Math., 34 (1991), 305-314.  doi: 10.1016/0377-0427(91)90091-W. [2] L. Abrahamsson and H. O. Kreiss, Numerical solution of the coupled mode equations in duct acoustics, J. Comput. Phy., 111 (1994), 1-14.  doi: 10.1006/jcph.1994.1038. [3] S. Acosta, S. Chow, J. Taylor and V. Villamizar, On the multi-frequency inverse source problem in heterogeneous media, Inverse Problems, 28 (2012), 075013. doi: 10.1088/0266-5611/28/7/075013. [4] H. Ammari, E. Iakovleva and H. Kang, Reconstruction of a small inclusion in a two-dimensional open waveguide, SIAM J. Appl. Math., 65 (2005), 2107-2127.  doi: 10.1137/040615389. [5] G. Bao and P. Li, Inverse medium scattering problems for electromagnetic waves, SIAM J. Appl. Math., 65 (2005), 2049-2066.  doi: 10.1137/040607435. [6] G. Bao and F. Triki, Reconstruction of a defect in an open waveguide, Sci. China Math., 56 (2013), 2539-2548.  doi: 10.1007/s11425-013-4696-8. [7] G. Bao and F. Triki, Stability for the multifrequency inverse medium problem, J. Differential Equations, 269 (2020), 7106-7128.  doi: 10.1016/j.jde.2020.05.021. [8] J. P. Berenger, A perfectly matched layer for the absorption of electromagnetic waves, J. Comput. Phys., 114 (1994), 185-200.  doi: 10.1006/jcph.1994.1159. [9] L. Bourgeois and S. Fliss, On the identification of defects in a periodic waveguide from far field data, Inverse Problems, 30 (2014), 095004. doi: 10.1088/0266-5611/30/9/095004. [10] L. Bourgeois and E. Lunéville, The linear sampling method in a waveguide: A modal formulation, Inverse Problems, 24 (2008), 015018. doi: 10.1088/0266-5611/24/1/015018. [11] D. Colton and A. Kirsch, A simple method for solving inverse scattering problems in the resonance region, Inverse Problems, 12 (1996), 383-393.  doi: 10.1088/0266-5611/12/4/003. [12] D. Colton and R. Kress, Inverse Acoustic and Electromagnetic Scattering Theory, Applied Mathematical Sciences, Springer-Verlag, Berlin, 1992. doi: 10.1007/978-3-662-02835-3. [13] S. Dediu and J. R. McLaughlin, Recovering inhomogeneities in a waveguide using eigensystem decomposition, Inverse Problems, 22 (2006), 1227-1246.  doi: 10.1088/0266-5611/22/4/007. [14] A. S. B.-B. Dhia, L. Chesnel and S. A. Nazarov, Perfect transmission invisibility for waveguides with sound hard walls, J. Math. Pures Appl., 111 (2018), 79-105.  doi: 10.1016/j.matpur.2017.07.020. [15] H. Dym and H. P. McKean, Fourier Series and Integrals, Academic Press New York, 1972. [16] P. Grisvard, Elliptic Problems in Nonsmooth Domains, Society for Industrial and Applied Mathematics, 2011. doi: 10.1137/1.9781611972030.ch1. [17] M. Isaev and R. G. Novikov, Hölder-logarithmic stability in Fourier synthesis, Inverse Problems, 36 (2020), 125003. doi: 10.1088/1361-6420/abb5df. [18] V. Isakov and S. Lu, Increasing stability in the inverse source problem with attenuation and many frequencies, SIAM J. Appl. Math., 78 (2018), 1-18.  doi: 10.1137/17M1112704. [19] M. Kharrat, O. Bareille, W. Zhou and M. Ichchou, Nondestructive assessment of plastic elbows using torsional waves: Numerical and experimental investigations, Journal of Nondestructive Evaluation, 35 (2016), 1-14.  doi: 10.1007/s10921-015-0324-6. [20] M. Kharrat, M. N. Ichchou, O. Bareille and W. Zhou, Pipeline inspection using a torsional guided-waves inspection system. part 1: Defect identification, International Journal of Applied Mechanics, 6 (2014). doi: 10.1142/S1758825114500343. [21] Y. Y. Lu, Exact one-way methods for acoustic waveguides, Math. Comput. Simulation, 50 (1999), 377-391.  doi: 10.1016/S0378-4754(99)00111-1. [22] W. McLean, Strongly Elliptic Systems and Boundary Integral Equations, Cambridge University Press, 2000. [23] M. Sini and N. T. Thanh, Inverse acoustic obstacle scattering problems using multifrequency measurements, Inverse Probl. Imaging, 6 (2012), 749-773.  doi: 10.3934/ipi.2012.6.749. [24] J. Todd, The condition of the finite segment of the Hilbert matrix, National Bureau of Standarts, Applied Mathematics Series, (1954), 109–119.
Representation of the three types of defects: in $(1)$ a local perturbation $q$, in $(2)$ a bending of the waveguide, in $(3)$ a localized defect in the geometry of $\Omega$. A controlled source $s$ generates a wave field $u^\text{inc}_k$. When it crosses the defect, it generates a scattered wave field $u^s_k$. Both $u^\text{inc}_k$ and $u^s_k$ are measured on the section $\Sigma$
Condition number of $M_t^TM_t$ for different sizes of support and values of $\omega_0$. Here, $X$ is the discretization of $[1-r, 1+r]$ with $500r+1$ points. The $x$-axis represents the evolution of $r$, and the $y$-axis $\text{cond}_2(M_t^TM_t)$. Each curve corresponds to value of $\omega_0$ as indicated in the left rectangle
Representation of a bend in a waveguide
Representation of a shape defect in a waveguide
Reconstruction of $f(x) = (x-0.8)(1.2-x)\textbf{1}_{0.8\leq x\leq 1.2}$ for different values of $\omega_1$ using the discrete operator $\gamma$ and the algorithm (91) with $\lambda = 0.001$. Here, $X$ is the discretization of $[0.5, 1.5]$ with $10\omega_1$ points, and $K$ is the discretization of $[0.01, \omega_1]$ with $1000$ points
$\text{L}^2$-error between $f(x) = (x-0.8)(1.2-x)\textbf{1}_{0.8\leq x\leq 1.2}$ and its reconstruction $f_{app}$ for different values of $\omega_1$ using the discrete operator $\gamma$ and the algorithm (91) with $\lambda = 0.001$. Here, $X$ is the discretization of $[0.5, 1.5]$ with $10\omega_1$ points, and $K$ is the discretization of $[0.01, \omega_1]$ with $1000$ points
Reconstruction of $f(x) = (x-0.8)(1.2-x)\textbf{1}_{0.8\leq x\leq 1.2}$ for different values of $\omega_0$ and $r = 0.5$ using the discrete operator $\gamma$ and the algorithm (91) with $\lambda = 0.001$. Here, $X$ is the discretization of $[0.5, 1.5]$ with $251$ points, and $K$ is the discretization of $[\omega_0, 50]$ with $1000$ points
Reconstruction of $f(x) = (x-0.8)(1.2-x)\textbf{1}_{0.8\leq x\leq 1.2}$ for different sizes of support $r$ and $\omega_0 = 3\pi$ using the discrete operator $\gamma$ and the algorithm (91) with $\lambda = 0.001$. Here, $X$ is the discretization of $[1-r, 1+r]$ with $500r+1$ points, and $K$ is the discretization of $[3\pi, 50]$ with $1000$ points
Reconstruction of two different bends. The black lines represent the initial shape of $\Omega$, and the red the reconstruction of $\Omega$. In both cases, $K$ is the discretization of $[0.01, 40]$ with $100$ points, and the reconstruction is obtain by (94). On the left, the initial parameters of the bend are $(x_c, r, \theta) = (4, 10, \pi/12)$ and on the right, $(x_c, r, \theta) = (2, 5, \pi/6)$
Reconstruction of a waveguide with two successive bends. The black lines represent the initial shape of $\Omega$, and the red the reconstruction of $\Omega$, slightly shifted for comparison purposes. In both cases, $K$ is the discretization of $[0.01, 40]$ with $100$ points. The parameters of the two bends are $(x_c^{(1)}, r^{(1)}, \theta^{(1)}) = (2, 10, \pi/30))$ and $(x_c^{(2)}, r^{(2)}, \theta^{(2)}) = (3.8, 8, -\pi/20))$
Reconstruction of two shape defects. In black, the initial shape of $\Omega$, and in red the reconstruction, slightly shifted for comparison purposes. In both cases, $K$ is the discretization of $[0.01, 70]\setminus \{[n\pi-0.2, n\pi+0.2], n\in \mathbb{N}\}$ with $300$ points, $X$ is the discretization of $[3, 4.5]$ with $151$ points and we use the algorithm (91) with $\lambda = 0.08$ to reconstruct $s_0$ and $s_1$. On the left, $h(x) = \frac{5}{16}\textbf{1}_{3.2\leq x\leq 4.2}(x-3.2)^2(4.2-x)^2$ and $g(x) = -\frac{35}{16}\textbf{1}_{3.4\leq x\leq 4}(x-3.4)^2(4-x)^2$. On the right, $h(x) = \frac{125}{16}\textbf{1}_{3.7\leq x\leq 4.2}(x-3.7)^2(4.2-x)^2$ and $g(x) = \frac{125}{16}\textbf{1}_{3.4\leq x\leq 4}(x-3.4)^2(4-x)^2$
Recontruction of $h_n$ for $0\leq n\leq 9$, where $h(x) = 0.05\textbf{1}_{\left|\left(\frac{x-4}{0.05}, \frac{y-0.6}{0.15}\right)\right|\leq 1}\left|\left(\frac{x-4}{0.05}, \frac{y-0.6}{0.15}\right)\right|^2$. In blue, we represent $h_n$ and in red the reconstruction of $h_{n_{\text{app}}}$. In every reconstruction, $K$ is the discretization of $[0.01, 150]$ with $200$ points, $X$ is the discretization of $[3.8, 4.2]$ with $101$ points and we use the algorithm (91) with $\lambda = 0.002$ to reconstruct every $h_n$
Recontruction of an inhomogeneity $h$, where $h(x) = 0.05\textbf{1}_{\left|\left(\frac{x-4}{0.05}, \frac{y-0.6}{0.15}\right)\right|\leq 1}\left|\left(\frac{x-4}{0.05}, \frac{y-0.6}{0.15}\right)\right|^2$. On the left, we represent the initial shape of $h$, and on the right the reconstruction $h_{\text{app}}$. Here, $K$ is the discretization of $[0.01, 150]$ with $200$ points, $X$ is the discretization of $[3.8, 4.2]$ with $101$ points and we use the algorithm (91) with $\lambda = 0.002$ to reconstruct every $h_n$. We used $N = 20$ modes to reconstruct $h$
Recontruction of an inhomogeneity $h$. From top to bottom, the initial representation of $h$, the reconstruction $h_{\text{app}}$ and the reconstruction $h_{\text{app}}$ with the knowledge of the positivity of $h$. Here, $K$ is the discretization of $[0.01, 150]$ with $200$ points, $X$ is the discretization of $[3, 6]$ with $3001$ points and we use the algorithm (91) with $\lambda = 0.01$ to reconstruct every $h_n$. We choose used $N = 20$ modes to reconstruct $h$
Relative errors on the reconstruction of $(x_c, r, \theta)$ for different bends. In each case, $K$ is the discretization of $[0.01, 40]$ with $100$ points, and the reconstruction is obtain by (94)
 $(x_c, r, \theta)$ $(2.5, 40, \pi/80)$ $(4, 10, \pi/12)$ $(2, 5, \pi/6)$ relative error on $x_c$ $1.8\%$ $0\%$ $7.6\%$ relative error on $r$ $3.0\%$ $7.5\%$ $23.8\%$ relative error on $\theta$ $1.6\%$ $10.7\%$ $16.9\%$
 $(x_c, r, \theta)$ $(2.5, 40, \pi/80)$ $(4, 10, \pi/12)$ $(2, 5, \pi/6)$ relative error on $x_c$ $1.8\%$ $0\%$ $7.6\%$ relative error on $r$ $3.0\%$ $7.5\%$ $23.8\%$ relative error on $\theta$ $1.6\%$ $10.7\%$ $16.9\%$
Relative errors on the reconstruction of $h$ for different amplitudes $A$. We choose $h(x) = A\textbf{1}_{3\leq x\leq 5}(x-3)^2(5-x)^2$ and $g(x) = 0$. In every reconstruction, $K$ is the discretization of $[0.01, 40]\setminus \{[n\pi-0.2, n\pi+0.2], n\in \mathbb{N}\}$ with $100$ points, $X$ is the discretization of $[1, 7]$ with $601$ points and we use the algorithm (91) with $\lambda = 0.08$ to reconstruct $h'$
 $A$ $0.1$ $0.2$ $0.3$ $0.5$ $\Vert h-h_{\text{app}}\Vert_{\text{L}^2( \mathbb{R})}/\Vert h\Vert_{\text{L}^2( \mathbb{R})}$ $8.82\%$ $10.41\%$ $15.12\%$ $54.99\%$
 $A$ $0.1$ $0.2$ $0.3$ $0.5$ $\Vert h-h_{\text{app}}\Vert_{\text{L}^2( \mathbb{R})}/\Vert h\Vert_{\text{L}^2( \mathbb{R})}$ $8.82\%$ $10.41\%$ $15.12\%$ $54.99\%$
 [1] Michael V. Klibanov, Dinh-Liem Nguyen, Loc H. Nguyen, Hui Liu. A globally convergent numerical method for a 3D coefficient inverse problem with a single measurement of multi-frequency data. Inverse Problems and Imaging, 2018, 12 (2) : 493-523. doi: 10.3934/ipi.2018021 [2] Loc H. Nguyen, Qitong Li, Michael V. Klibanov. A convergent numerical method for a multi-frequency inverse source problem in inhomogenous media. Inverse Problems and Imaging, 2019, 13 (5) : 1067-1094. doi: 10.3934/ipi.2019048 [3] María Ángeles García-Ferrero, Angkana Rüland, Wiktoria Zatoń. Runge approximation and stability improvement for a partial data Calderón problem for the acoustic Helmholtz equation. Inverse Problems and Imaging, 2022, 16 (1) : 251-281. doi: 10.3934/ipi.2021049 [4] Michael V. Klibanov. A phaseless inverse scattering problem for the 3-D Helmholtz equation. Inverse Problems and Imaging, 2017, 11 (2) : 263-276. doi: 10.3934/ipi.2017013 [5] Karzan Berdawood, Abdeljalil Nachaoui, Rostam Saeed, Mourad Nachaoui, Fatima Aboud. An efficient D-N alternating algorithm for solving an inverse problem for Helmholtz equation. Discrete and Continuous Dynamical Systems - S, 2022, 15 (1) : 57-78. doi: 10.3934/dcdss.2021013 [6] Kaitlyn (Voccola) Muller. A reproducing kernel Hilbert space framework for inverse scattering problems within the Born approximation. Inverse Problems and Imaging, 2019, 13 (6) : 1327-1348. doi: 10.3934/ipi.2019058 [7] Suman Kumar Sahoo, Manmohan Vashisth. A partial data inverse problem for the convection-diffusion equation. Inverse Problems and Imaging, 2020, 14 (1) : 53-75. doi: 10.3934/ipi.2019063 [8] Li Liang. Increasing stability for the inverse problem of the Schrödinger equation with the partial Cauchy data. Inverse Problems and Imaging, 2015, 9 (2) : 469-478. doi: 10.3934/ipi.2015.9.469 [9] Soumen Senapati, Manmohan Vashisth. Stability estimate for a partial data inverse problem for the convection-diffusion equation. Evolution Equations and Control Theory, 2021  doi: 10.3934/eect.2021060 [10] Shuyang Dai, Fengru Wang, Jerry Zhijian Yang, Cheng Yuan. On the Cauchy-Born approximation at finite temperature for alloys. Discrete and Continuous Dynamical Systems - B, 2022, 27 (6) : 3131-3153. doi: 10.3934/dcdsb.2021176 [11] Enrico Capobianco. Born to be big: Data, graphs, and their entangled complexity. Big Data & Information Analytics, 2016, 1 (2&3) : 163-169. doi: 10.3934/bdia.2016002 [12] Ioan Bucataru, Matias F. Dahl. Semi-basic 1-forms and Helmholtz conditions for the inverse problem of the calculus of variations. Journal of Geometric Mechanics, 2009, 1 (2) : 159-180. doi: 10.3934/jgm.2009.1.159 [13] Pedro Caro. On an inverse problem in electromagnetism with local data: stability and uniqueness. Inverse Problems and Imaging, 2011, 5 (2) : 297-322. doi: 10.3934/ipi.2011.5.297 [14] Victor Isakov. On uniqueness in the inverse conductivity problem with local data. Inverse Problems and Imaging, 2007, 1 (1) : 95-105. doi: 10.3934/ipi.2007.1.95 [15] Xiaoxu Xu, Bo Zhang, Haiwen Zhang. Uniqueness in inverse acoustic and electromagnetic scattering with phaseless near-field data at a fixed frequency. Inverse Problems and Imaging, 2020, 14 (3) : 489-510. doi: 10.3934/ipi.2020023 [16] S. L. Ma'u, P. Ramankutty. An averaging method for the Helmholtz equation. Conference Publications, 2003, 2003 (Special) : 604-609. doi: 10.3934/proc.2003.2003.604 [17] Nguyen Huy Tuan, Mokhtar Kirane, Long Dinh Le, Van Thinh Nguyen. On an inverse problem for fractional evolution equation. Evolution Equations and Control Theory, 2017, 6 (1) : 111-134. doi: 10.3934/eect.2017007 [18] Lili Chang, Wei Gong, Guiquan Sun, Ningning Yan. PDE-constrained optimal control approach for the approximation of an inverse Cauchy problem. Inverse Problems and Imaging, 2015, 9 (3) : 791-814. doi: 10.3934/ipi.2015.9.791 [19] John Sylvester. An estimate for the free Helmholtz equation that scales. Inverse Problems and Imaging, 2009, 3 (2) : 333-351. doi: 10.3934/ipi.2009.3.333 [20] Francis J. Chung. Partial data for the Neumann-Dirichlet magnetic Schrödinger inverse problem. Inverse Problems and Imaging, 2014, 8 (4) : 959-989. doi: 10.3934/ipi.2014.8.959

2020 Impact Factor: 1.639