gas-lift pumps are devices for lifting liquid phase incorporating the gas phase to be injected in the bottom of liquid column. they are widely used in various industrial applications such as oil extracting in petroleum industries. gas-liquid flow being the main part of the flow through these systems, flowing in vertical pipes of gas-lift pumps has different regimes namely bubbly, slug, churn an...

polymer-clay nano-composite materials, in which nano-meter thick layers of clay dispersed in polymer matrix, have generally higher mechanical properties than normal polymeric materials. a new three-dimensional unit cell model has been developed for modeling three constituent phases including inclusion, interphase and matrix. the total elastic modulus of nano-composite is evaluated.  numerical r...

in this paper, the reduced dierential transform method is investigated fora nonlinear partial dierential equation modeling nematic liquid crystals, itis called the hunter-saxton equation. the main advantage of this methodis that it can be applied directly to nonlinear dierential equations withoutrequiring linearization, discretization, or perturbation. it is a semi analytical-numerical metho...

most of river engineering problems are complicated and need to be analyzed by three dimensional models of flow and sediment transport. considering the fact that computers and numerical methods with great ability of flow and sediment transport simulation are developing quickly, using numerical modeling by engineers is inevitable. nevertheless, before application, numerical models need to be veri...

most of the earth's crust contains fluids, and fractures are common throughout the upper part. they exist at a wide range of scales from micro-fractures within grains to major faults and shear zones that traverse the crust. in this paper, the stress-dependent permeability in fractured rock masses have been investigated considering the effects of nonlinear normal deformation and shear dilation o...

[1] The Thurwieser landslide that occurred in Italy in 2004 and the seismic waves it generated have been simulated and compared to the seismic signal recorded a few tens of kilometers from the landslide source (i.e., landquake). The main features of the low frequency seismic signal are reproduced by the simulation. Topography effects on the flowing mass have a major impact on the generated seis...

the effect of underground cavities in site seismic response was studied over the subway tunnels that are under construction in the city of karaj, using ambient noise measurements as well as numerical modeling. the idea for this research comes from the observation of differences in experimental site transfer function, calculated on more than 100 locations of the city, for the areas near the unde...