an analytical treatment of the electron screening effect within an active-electron model is given for positronium formation from helium atoms. a first-order distorted wave approximation with correct boundary conditions is applied to evaluate the transition amplitude. in the range of impact energy for which the introduced perturbative approach is valid, both the total and differential cross sect...

according to high costs of phase shifters in antenna arrays, new methods for beam steering without phase shifter were introduced. frequency diverse array (fda) concept is another approach to beam steering problem. in this structure, the subsequent antenna elements are fed with stepped discrete frequencies causing continuous scanning of space in time. so a range-angle dependent scanning is made ...

With an extended mapping approach and a linear variable separation approach, a series of solutions (including the Weierstrass elliptic function solutions, solitary wave solutions, periodic wave solutions and rational function solutions) of the (2+1)-dimensional modified dispersive water-wave system (MDWW) is derived. Based on the derived solutions and using some multi-valued functions, we find ...

A brief introduction to the projector augmented wave method is given and recent developments are reviewed. The projector augmented wave method is an all-electron method for efficient ab-initio molecular dynamics simulations with full wave functions. It extends and combines the traditions of existing augmented wave methods and the pseudopotential approach. Without sacrificing efficiency, the PAW...