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A Method of Elastic Wave Imaging Based on Inhomogeneous Background Medium

An imaging method and non-uniform technology, which can be used in seismic signal processing and other directions, and can solve the problems of inability to obtain object material parameters and large limitations.

Active Publication Date: 2020-01-31
HANGZHOU DIANZI UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] In the development process of the elastic wave imaging method, in the early stage, the linear algorithm was mainly used, but its limitation is relatively large, and only some simple information can be obtained, such as the synthetic aperture radar technology, which can only obtain the approximate position of the object and shape, but cannot obtain relevant information such as object material parameters

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  • A Method of Elastic Wave Imaging Based on Inhomogeneous Background Medium
  • A Method of Elastic Wave Imaging Based on Inhomogeneous Background Medium
  • A Method of Elastic Wave Imaging Based on Inhomogeneous Background Medium

Examples

Experimental program
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Embodiment 1

[0172] The experimental device structural diagram that the present invention design adopts is as figure 2 As shown, this example uses experimental simulation data to verify the proposed elastic wave imaging method. The simulation example is a profile composed of a rectangular frame and a ring. The profile lies in a square region of side length 2λ, where λ is the wavelength of the incident wave. Uneven background consisting of rectangular frames and free space. The centers of both the ring and the rectangle are located at (0, 0). The outer radius of the ring is 0.4λ and the inner radius is 0.2λ. The outer wall length of the rectangular frame is 1.6λ, and the inner wall length is 1.2λ. As a non-uniform background, the relative permittivity of the rectangular frame is known to be 2.0, and the relative permittivity contrast of the ring is 4.0. The domain is discretized into a 30 × 30 grid, and 16 incident points uniformly distributed on a 2π solid angle are used as transmitte...

Embodiment 2

[0174] In order to verify the imaging effect of the elastic wave imaging method designed in the present invention on the measured data, the structure diagram of the experimental device in Example 1 is still used in this example 2, and the corresponding actual experimental measurement device is built. We have measured the two models, and imaged using the calibrated experimental data. The rectangular framed walls of both models are made of Teflon material. The wall is a square structure. It has a side length of 21cm and a thickness of 1cm. The first model is a K-type scatterer consisting of two U-shaped scatterers back-to-back. The U-shaped scatterer has a relative permittivity of about 3. The lower U-shaped scatterer has a side length of The structure has a side length of 10 cm. Their thickness is 1 cm. The second model is a cylindrical scatterer. The radius of the cylinder is about 5cm, the relative permittivity is about 3, and the position is at (-2.5, -7.5)cm. The imagin...

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Abstract

The invention discloses an elastic wave imaging method based on a non-uniform background medium, so as to reconstruct an unknown target embedded in the non-uniform background medium. The non-uniform background is treated as the wall surface of a known scatterer in a finite field, which has the advantage of avoiding the time-consuming calculation of the Green's function in the non-uniform background. Under this scheme, a novel method (ME-LM) based on a differential integral equation model is proposed in conjunction with an improved Levenberg Marquardt (LM) algorithm to achieve image reconstruction. In addition, the improved generalized cross validation (GCV) regularization technique is used to adaptively select the regularization parameters in the iteration, which improves the stability ofthe iterative process. The results show that the proposed method not only has fast calculation speed, good convergence, but also can reduce nonlinearity and can reconstruct unknown scatterer with highbackground contrast. Both the simulation test and the actual test verify the effectiveness of the method.

Description

technical field [0001] The invention belongs to the technical field of elastic wave imaging, and proposes an elastic wave imaging method based on a non-uniform background medium. Background technique [0002] In production practice, we humans often use our own sensing organs, such as eyes, nose, ears, etc., to intuitively feel and obtain external information. For example, images obtained through the eyes contain a huge amount of information. However, for some fields, such as the microscopic field, the ocean field, etc., due to the limitations of human senses, it is not enough to obtain more useful information through the human senses alone, and the information obtained through the senses is very limited, so humans have invented various Some tools are used to expand the range of human senses, and some of the methods of inventing tools are used to replace eyes, and this type of method belongs to the imaging method. The basic principle of the imaging method is to use the corre...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01V1/28
CPCG01V1/28
Inventor 徐魁文楚彦青赵文生陈世昌赵鹏王高峰
Owner HANGZHOU DIANZI UNIV