No abstract

In this paper, we present the two-step trigonometrically fitted symmetric Obrechkoff methods with algebraic order of twelve. The method is based on the symmetric two-step Obrechkoff method, with 12 algebraic order, high phase-lag order and is constructed to solve IVPs with periodic solutions such as orbital problems. We compare the new method to some recently constructed optimized methods from the literature. The numerical results obtained by the new method for some problems show its superiority in efficiency, accuracy and stability.

A thin elastic plate extending to infinity is immersed in a perfect gas. The response of this system to a spherical harmonic sound source is studied, and an exact representation of the solution is developed. From this result, a series representation useful to calculate the farfield is established; expressions for the various mean powers are given.