To study electromagnetic scattering by vehicle above ground,a half-space multilevel fast multipole algorithm (MLFMA) is proposed.Near terms in the MLFMA are evaluated by rigorous half-space dyadic Green functions.Far MLFMA interactions employ an approximate dyadic Green function via a direct-radiation term plus a single real image.The real image method leads to fast and convenient computation compared with the discrete complex image method (DCIM).It also results in less memory requirement and CPU time.Finally,bistatic radar cross sections are shown for a realistic 3D car model over lossy ground.

This paper deals with the finite element approximation of the axisymmetric Stokes flow on unbounded domains. In order to overcome the difficulties caused by the unbounded domains, the finite element method is combined with the classical analytical method and the equivalent boundary value problem on bounded domains is obtained, which is solved numerically by the finite element techneque. As an example, the Stokes flow around the sphere is calculated and the error estimate of the approximate solutions is given.