基于自适应纯形模拟退火法一维大地电磁测深视电阻率和相位反演研究

One dimensional magnetotelluric sounding apparent resistivity and phase inversion of adaptive simplex simulated annealing study

针对大地电磁测深反演中线性化方法容易陷入局部极值,而全局优化方法收敛慢等问题,这里采用自适应纯形模拟退火综合优化方法进行大地电磁测深数据反演。该优化方法综合了下降纯形法和模拟退火法各自的优点,已被证明具有全局搜所能力和收敛速度快的特点,并且实现了视电阻率和相位同时反演,减小多解性的同时提高了反演的分辨率。通过H、K和HKH型模型的数值计算,验证了这种综合优化方法的搜索效率和全局收敛性;所有模型合成数据的反演结果都能较好地反映真实模型的结构特征。对于中间层为相对高阻的模型,虽然相对其他层结构恢复差些,但是反演后该层结构基本得到恢复。

In order to avoid the linear inversion of MT falling into local extremum,and slow convergence rate of global optimization method,the authors adopt a comprehensive optimization method of adaptive simplex simulated annealing to the inversion of MT.On the one hand,this method could combine the advantages of both downhill simplex and simulate anneal arithmetic,which is proved to be a good way with global search capability and high-speed convergence.On the other hand,it achieved the simultaneously inversion of apparent resistivity and phase,which leads to the result of reducing the multi solutions and increasing resolution.Through numerical calculation of H,K and HKH models,this method shows high search efficiency and global convergence of comprehensive optimization method.The structure characteristics of real model could be reflected by inversion result of all the model synthetic data.As for some intermediate layers are relative high resistance models,the structures still could recover after inversion even if they are relative bad to other layers.