Ultrasound Tomography Based On Space Domain

In general，there are defects and inclusions are always exists in the structure and materialfor the erosion and corrosion of environment as well as the effect of the production process.With the passage of time, there will be a serious damage, and even lead to fracture, then it willgenerate disaster results. Therefore, the method of using the technology of ultrasonictomography to detect objects is possessed of visual display and low price, has been one of thehotspots in non-destructive testing.In this paper, we study the method of ultrasound inverse scattering imaging based onwave-theory. First, proceeding from the Helmholz equation, the method of solve the inversescattering problem is given. Subsequently, the data model of inverse scattering ofinhomogeneous medium is established, meanwhile, the numerical simulation is given. Theresearch achievement is acquired as follows:1. Based on the mathematical model of inverse scattering that is two-dimensional andnon-uniform media, positive scattering problem and the inverse scattering problem arerespectively considered, and the ill-posed integral equations are deduced. Scattering field andtotal field equation problem are discretization by using the method of moments.2. The nonlinear problem of wave equation is studied. Using iterative method are easilyintroduced the known information, the solution to parallel processing, in the solving process,using iterative approximation of the solution of the problem to solve the nonlinear problemsof equation .3. The stability of the wave equation is discussed by using the method of regularization.the main reason why The least-squares solution of ill-posed equations instability is that theeffection of small singular value and the corresponding singular vector on the solution, so inthe method of truncated singular value decomposition, we can choose proper regularizationparameters and directly truncated the item which is behind the number of regularizationparameters in the least-squares solution, then we will achieve the purpose of the regularized.4. In the regular method, choosing truncated parameters k played a crucial role in theregular method, in this paper we revised the strategies of parameters that is making aone-dimension search in the corner of L-curve to confirm the best regularization parameter. Experiment model is designed based on the method of array imaging, and it can beregularized after being distinguished by Picard criterion. The nonlinear of wave equation issolved by the method of iterative, and the stability of wave equation is solved by truncatedsingular value decomposition regularization method. The experiments prove that the methodof tomography can be applied to the case of strong scattering, and has higher image quality.