Study About1D Forward And Inversion Of SAEM

Semi-Airborne Time-domain Electromagnetic Method(SAEM) what is laid onthe ground a few kilometers of line source or a large loop source, and using thehelicopters in the air to achieve the purpose of the received signal to detectunderground geologic targets. Semi-airborne electromagnetic exploration methodduring a large area, which also can save a lot of manpower and material resources,and exploration depth is the same as TEM.1D forward and inversion is a core part ofof SAEM, this paper focuses on1D forward and inversion of SAEM, and mainly tocomplete the following tasks:(1)To Maxwell’s equations, Detailed derivation of the formula of SAEM. Wederived formula of horizontal electric dipole in the case of horizontal layered media.(2) Forward response curve analysis. By analyzing the surface magnetic fieldperpendicular cross-sectional view of the number of partial derivatives, obtainedunder the uniform half-space, the plane of the aircraft in the50-150m height is themost appropriate. Analysis of the response curves from different offset homogeneoushalf space, the field value with the offset from the first larger increases and thendecreases, if you want the best value Early Road, offset should be100-150m, whenthe late road to the best offset should be800-1000m. And analysis of thecharacteristics of different resistivity response curve of a uniform half-space, analysisof the response curves G-and D-type electrical structure of two different, and Analysisof the response curves H-and K-type electrical structure of three different.(3) Study about1D inversion of SAEM. Detailed study of the basic principles ofadaptive regularized inversion algorithm (ARIA), and ARIA is applied to SAEM.ARIA inversion method relies on the initial model is relatively low. The variance ofthe data are standardized method, so only the variance of the size of the data fit theimpact occurs, the weight data is not the objective function objective function and theconstraint model heavy impact, thereby reducing the value of the regularization factorin. this method has two regularization factor adaptive method. This paper studies theflattest model constrained semi aviation electromagnetic ARIA, for four typicalthree-layer model and the six model inversion results, a relatively poor fit,regularization detailed analysis and discussion of test results and other factors indicatethat ARIA is effective and has a good stable convergence. (4)Study about MPI of1D inversion of SAEM. we study the structure of the MPIprogram framework,6basic function of MPI, and the two basic modes for the MPIprogramming and so on. By Analysing time-consuming of SAEM each parts, we findthat the calculation time cosuming of Jacobi matrix and forward is the most, then weuse the master-slave mode to write inversion parallel programs of SAEM, and theparallel program calculation flow chart is presented. And compared with the inversionresult and Relatively poor fitting of serial and parallel programs, the results show thatthe parallel algorithm and program is accurate and reliable. Finally, on a dual-coredual-threaded, dual and quad-core four threads eight threads of different computerstested the efficiency of parallel algorithms. The results showed that: MPI efficiencydirectly related to the threads, and speedup is no more than threads.