We propose a method to invert two parameters(virgin zone resistivity,invaded zone) of dual lateral logging which is based on Newton-SVD of particle swarm.Reasonable initial values are selected by random particle swarm method.Newton-SVD is applied to invert dual lateral logging data.It improves stability and reliability of logging inversion greatly,and offers a radical way for setting initial values of inversion.Ideal model with noise and practical logging data are compared.It shows that the method eliminates effects of complex logging environments effectively and offer true formation parameters.

The instantaneous response of a laminar diffusion flamelet is investigated numerically. A detailed mechanism GRI-Mech 3.0(53-species and 325-reaction) is empolyed to describe the CH₄ oxidation and NO_x formation. A predication of steady flamelct structures is compared with the experimental data to validate the method. A step variation of strain rate is used to simulate the influence of a instantaneous flow field on the flamelet local structure. The response of flamelet structures(temperature and species concentration) to the strain rate variation is given and analyzed. We focus on the influence of the step size of the strain rate. It is found that the flamelet response to the strain rate variation is not symmetric,and the response time is inverse proportional to the strain rate variation as it is small. In addition, the mean response time of temperature is much longer than the flow time scale of a typical turbulent combustion field, which demonstrates the importance of unsteadiness in the numerical simulation of turbulent combustions.

Based on the stream function-vorticity expression a discrete procedure is employed to approximate the imcompressible fluid with zero viscosity,in which the vorticity is approximated by finite difference along its streamline,the velocity field and the stream function are approximated simultaneously by a mixed finite element.The analysis shows that the procedure possesses both high accuracy and good stability which are not shared by standard methods.