Numerical simulation of spherically imploding detonation waves in hydrogen-oxygen is carried out in an elementary chemical reaction model.Compared with numerical results of imploding shock waves in nitrogen,the discrepancies of gas dynamic characteristics between shock and detonation waves are investigated during implosion.The effect of chemical reactions,combustion and dissociation on detonation waves is revealed.As the wave fronts converge toward the center of symmetry,the front pressures at different radii are almost the same in the two cases.However the front temperatures are different.The temperature increases more rapidly in nitrogen than in hydrogen-oxygen mixture.Higher temperature is reached near the focal point in nitrogen due to its higher dissociation temperature.The energy released at the wave front is negligible in predicting pressure,while it needs to be considered in predicting temperature.

The numerical solution of Green's function for potential in axisymmetrically stratified media with axial inhomogenity is given using the duality of the hybrid method,which is then applied to the computation of response of the fundamental resistivity tool.Compared with the 2D finite element method,this algorithm is of higher efficiency because of the reduction of the problem dimension.