Calculation of all-time apparent resistivity of large loop transient electromagnetic method with very fast simulated annealing  

作　　者：李建慧 朱自强 冯德山 肖建平 彭凌星 

机构地区：[1]School of Earth Sciences and Info-physics,Central South University

出　　处：《Journal of Central South University》2011年第4期1235-1239,共5页中南大学学报（英文版）

基　　金：Projects(40804027,41074085) supported by the National Natural Science Foundation of China;Project(09JJ3048) supported by the Natural Science Foundation of Hunan Province,China;Project(200805331082) supported by the Research Fund for the Doctoral Program of Higher Education,China

摘　　要：In large loop transient electromagnetic method(TEM),the late time apparent resistivity formula cannot truly reflect the geoelectric model,thus it needs to define the all-time apparent resistivity with the position information of measuring point.Utilizing very fast simulated annealing(VFSA) to fit the theoretical electromagnetic force(EMF) and measured EMF could obtain the all-time apparent resistivity of the measuring points in rectangular transmitting loop.The selective cope of initial model of VFSA could be confirmed by taking the late time apparent resistivity of transient electromagnetic method as the prior information.For verifying the correctness,the all-time apparent resistivities of the geoelectric models were calculated by VFSA and dichotomy,respectively.The results indicate that the relative differences of apparent resistivities calculated by these two methods are within 3%.The change of measuring point position has little influence on the tracing pattern of all-time apparent resistivity.The first branch of the curve of all-time apparent resistivity is close to the resistivity of the first layer medium and the last branch is close to the resistivity of the last layer medium,which proves the correctness of the arithmetics proposed.In large loop transient electromagnetic method （TEM）, the late time apparent resistivity formula cannot truly reflect the geoelectric model, thus it needs to define the all-time apparent resistivity with the position information of measuring point. Utilizing very fast simulated annealing （VFSA） to fit the theoretical electromagnetic force （EMF） and measured EMF could obtain the all-time apparent resistivity of the measuring points in rectangular transmitting loop. The selective cope of initial model of VFSA could be confirmed by taking the late time apparent resistivity of transient electromagnetic method as the prior information. For verifying the correctness, the all-time apparent resistivities of the geoelectric models were calculated by VFSA and dichotomy, respectively. The results indicate that the relative differences of apparent resistivities calculated by these two methods are within 3%. The change of measuring point position has little influence on the tracing pattern of all-time apparent resistivity. The first branch of the curve of all-time apparent resistivity is close to the resistivity of the first layer medium and the last branch is close to the resistivity of the last layer medium, which proves the correctness of the arithmetics proposed.

关 键 词：very fast simulated annealing （VFSA） large loop transient electromagnetic method rectangular loop all-time apparent resistivity 

分 类 号：O441.4[理学—电磁学]