in this paper, the operation of helix traveling wave tube in interaction region is investigated by using a three dimensional large signal lagrangian model in frequency domain. the complete simulation of these tubes is essential for optimum design and minimum manufacturing cost. this 3d code can compute interception current (or current losses ), beam radius changes in interaction region and the ...

in this paper, a new algorithm for studying elastic wave propagation in the phononic crystals is presented. at first, the displacement-based forms of elastic wave equations are derived and then the forms are discretized using finite difference method. so the new algorithm is called the displacement-based finite difference time domain (dbfdtd). three numerical examples are computed with this met...

in this paper energy bands and berry curvature of graphene was studied. desired hamiltonian regarding the next-nearest neighbors obtained by tight binding model. by using the second quantization approach, the transformation matrix is calculated and the hamiltonian of system is diagonalized. with this hamiltonian, the band structure and wave function can be calculated. by using calculated wave f...

breaking waves have ability to transport large quantities of sediment and significant impact on coastal structures morphology. hence, modeling of wave breaking is an important subject in coastal and marine engineering. in this research, the periodic wave breaking process on a plane slope is studied experimentally and numerically. laboratory experiments were conducted to record water surface ele...

In this study, torsional wave propagation is investigated in a rod that are made of one and two dimensional functionally graded material. Firstly, the governing equations of the wave propagation in the functionally graded cylinder derived in polar coordinate. Secondly, finite difference method is used to discretize the equations. The Von Neumann stability approach is used to obtain the time ste...

In recent years reflectarray antennas have received considerable attention due to their unique capabilities. However, due to their large size, analyzing the performance of these antennas using traditional full wave finite-difference and finite-element techniques requires considerable computational resources. In this paper, we present an efficient method to accurately analyze these class of ante...