Integral equation method is one of effective methods of numerical simulation and inversion calculation for multi-dimensional electromagnetic response.Based on the linearization of the scattering electromagnetic integral equation, conductance imaging using iterative Born approximation is effective.Aiming at the characteristics that iterative Born approximation inversion depends on the initial model and that QL approximation doesn't need initial value, the two step method,iterative QL-Born approximation method,is put forward,which takes the result of QL inversion as the initial model of the iterative Born approximation method and avoids contrived initialization.The iterative QL-Born approximation method is effective and testified by numerical experiments

A new numerical method-nodal green's function method is used for solving heat conduction function. A heat conduction problem in cylindrical geometry with axial conduction is solving in this paper.The Kirchhoff transformation is used to deal with the problem with temperature dependent conductivity. There for the calculation for the function is simplified. On the basis of the formulas developed, the code named NGMEFC is programmed. A sample problem which has been calculated by the code GOBRA-Ⅳ is chosen as the check problem. A good agreement is achieved between both codes.The calculation shows that the calculation efficiency of the nodel green's function method is much higher than that of finite difference method.