The Study Of Stereotomography Method

Tomography method can use the specific parameters that received from somewhere outside the acoustic propagation medium to get the image of physical structure of the medium, so that it can reflect structure properties of material intuitively. Tomography method have the advantage of wide detection range and high resolution, so it is generally used in the field of practical production. But traditional travel-time tomography method is hard to pick up the data, and can generate ray multi-path phenomenon. This article studies the stereotomography method, which is aimed at improving the shortcomings of tomography method. This paper mainly includes the following content :First of all, first part of this paper summarizes the history and present situation of the tomography method, and clarifies the significance of this research topic. Second part of this paper introduces the basic knowledge systematically involved in the tomography method, including the physical basis : the propagation rules of sound waves in the medium; then introduces the mathematical foundation which the stereotomography method is based on, and the basic steps and the calculation process of the stereotomography method.Secondly, in order to avoid the instability of two-point ray tracing in the traditional tomography method, this paper uses the initial ray tracing in the forward calculation, and uses the nonlinear least squares method in the inversion calculation. This paper defines a new data space in the inversion calculation, when inputting data in the inversion the stereotomography method increases the local propagation directions when the sound waves arrived at the receivers on the basis of travel-time data. At the same time, reduces the inversion calculation by reducing the size of the inversion of the data according to the law of inversion calculation. This paper studies the implementation of stereotomography method on this basis, gets the structure distribution of the medium for sound waves through inversion calculation.Finally, the fourth chapter verifies the feasibility of this method and tests its imaging quality through difference structure of the medium models, and uses models to test theinfluence of the various parameters in the stereotomography method.