asymptotically exact and nonlocal fourth order nonlinear evolution equations are derived for two coupled fourth order nonlinear evolution equations have been derived in deep water for two capillary-gravity wave packets propagating in the same direction in the presence of wind flowing over water.we have used a general method, based on zakharov integral equation.on the basis of these evolution eq...

we consider a new type of integrable coupled nonlinear schrodinger (cnls)equations proposed by our self [submitted to phys. plasmas (2011)]. the explicitform of soliton solutions are derived using the hirota's bilinear method.we show that the parameters in the cnls equations only determine the regionsfor the existence of bright and dark soliton solutions. finally, throughthe linear stabili...

A new set of reduced equations governing two-dimensional, two-fluid, collisionless magnetic reconnection with arbitrary guide-field is derived. These equations represent a significant advance in magnetic reconnection theory, since the existing reduced equations used to investigate collisionless reconnection are only valid in the large guide-field limit. The new equations are used to calculate t...

Using harmonic differential quadrature (HDQ) method, nonlinear vibrations and instability of a smart composite cylindrical shell made from piezoelectric polymer of polyvinylidene fluoride (PVDF) reinforced with boron nitride nanotubes (BNNTs) are investigated while clamped at both ends and subjected to combined electro-thermo-mechanical loads and conveying a viscous-fluid. The mathematical mode...

A new theory for transverse instability of bright solitons of equations of nonlinear Schrödinger (NLS) type is presented, based on a natural deformation of the solitons into a four-parameter family. This deformation induces a set of four diagnostic functionals which encode information about transverse instability. These functionals include the deformed power, the deformed momentum and two new f...

the capability of sand constitutive models is remarkably improved by taking into account the effect of soil state in their formulations. in this study, it has been shown that considering the effect of soil state leads to better simulation of soil instability of shear banding type. to this aim, constitutive equations of a state dependent sand model are explained first. consequently, the general ...

rayleigh-taylor (rt) instability has a growing importance in many fields including aircraft industry and astrophysics. the development and the growth of rt instability were investigated using sinusoidal disturbances with different wavelength at the interface of two fluids. numerical simulations were performed by solving navier-stokes unsteady equations with the vof formulation. results of the 2...

The capability of sand constitutive models is remarkably improved by taking into account the effect of soil state in their formulations. In this study, it has been shown that considering the effect of soil state leads to better simulation of soil instability of shear banding type. To this aim, constitutive equations of a state dependent sand model are explained first. Consequently, the general ...

The dynamic instability of single-walled carbon nanotubes (SWCNT), double-walled carbon nanotubes (DWCNT) and triple-walled carbon nanotubes (TWCNT) embedded in an elastic medium under combined static and periodic axial loads are investigated using Floquet–Lyapunov theory. An elastic multiple-beam model is utilized where the nested slender nanotubes are coupled with each other through the van d...