The goals of this career program are to develop efficient forward and inverse techniques to solve electromagnetic and elastodynamic problems in geophysical subsurface sensing, and to foster an effective, interdisciplinary educational program. In geophysical subsurface sensing, electromagnetic and acoustic sensors are widely used to probe the complex geological structures from within a borehole. The interpretation of these important measurements, however, remains a challenging problem because of the complexity of the underground medium and of the presence of the wellbore. Simulating realistic three-dimensional models encountered in these problems can easily exceed the capacity of any modern supercomputer if conventional methods are used. Therefore, there is a pressing demand for more efficient numerical techniques to simulate large-scale electromagnetic and acoustic measurements. These simulations are also critical in processing the collected data and in computer-aided design of new measurement systems. In this research, efficient forward and inverse solutions will be developed for electrodetype, induction, and sonic well logging tools in three-dimensional inhomogeneous media. In forward solutions, the measurement data are simulated given the physical properties of the medium. In inverse problems, on the other hand, the physical properties of the medium are determined from the measurement data, which is the ultimate goal of geophysical subsurface sensing. As the focus of research, a series of efficient forward models will be developed as a backbone of nonlinear inversion for 3-D electromagnetic and elastodynamic problems. The techniques proposed will allow one to solve much larger problems than conventional finite-difference and finite-element methods on a supercomputer. The forward solutions will be effectively coupled with the inverse algorithms. In the educational program, the principal investigator (PI) proposes to strengthen the interactions among faculty members and students in electrical engineering, geophysics, and mechanical engineering departments by developing interdisciplinary courses and by collaboration. Three new cross-department courses will be developed, and the use of computers and network in electromagnetic education will be incorporated to improve the teaching effectiveness. The research program will be fully integrated with the undergraduate and graduate electrical engineering education. This integrated career program Will significantly advance the capability of simulating large-scale forward and inverse electromagnetic and elastodynamic problems in geophysical subsurface sensing. The petroleum industry will benefit from this research program through the publication of knowledge and software developed. This program will also benefit subsurface mapping of underground buried waste and the medical imaging industry. The students involved in this research will have the unique opportunity to acquire interdisciplinary knowledge on the applications of electrical engineering in geophysical exploration.
