the occurrence of dust storms and their sources in the southern and central parts of iran during the period of 2002 to 2009 was investigated. for this purpose, the meteorological and synoptic data, data from the middle and upper atmosphere, and wind flow tracking model were used. dust storms and nddi were traced using satellite imagery from fasa, shiraz, and bushehr stations. analysis of the gr...

Melt generation and migration are important processes for the evolution of the Earth’s interior and impact the global convection of the mantle. While they have been the subject of numerous investigations, the typical time and lengthscales of melt transport are vastly different from global mantle convection, which determines where melt is generated. This makes it difficult to study mantle convec...

in recent years, impinging streams have received increasing interest for their high efficiency in heat and mass transfer. this numerical study was conducted to investigate flow and heat transfer characteristics of one-way opposing jets of non-newtonian fluids. effects of reynolds number impinging angle, momentum ratio and flow behavior index on mixing index were evaluated. the results showed im...

A numerical model is developed to describe the flow and heat transfer behavior of liquid metals in a cold delivery tube during gas atomization. Numerical calculations for liquid In, Sn, Bi, Pb, Zn and Sb are performed to investigate the influence of processing parameters and material properties on the flow and cooling of the liquid metals, and to predict the minimum melt superheat that is neces...

Investigations for the melt growth gallium-antimonide (GaSb) semiconductor crystals are underway at the US Air Force Research Laboratory at Hanscom Air Force Base by the vertical gradient freeze (VGF) method utilizing a submerged heater. Electromagnetic stirring can be induced in the gallium-antimonide melt just above the crystal growth interface by applying a weak radial electric current in th...

Motion of growing dendrites is a common phenomenon during solidification but often neglected in numerical simulations because of the complicate underlying multiphysics. Here a phase-field model incorporating dendrite-melt two-phase flow is proposed for simulating the dynamically interacted process. The proposed model circumvents complexity to resolve dendritic growth, natural convection and sol...

High-density polyethylene (HDPE) and polypropylene (PP) blends of varying composition have been evaluated in an effort to establish a mixing rule for melt flow index (MFI). In addition, previously established relationship between MFI M w ¯ $$ \overline{M_w} linear polymers was also these blends. It found that parabolic existed the (by weight fraction) held this set polymeric materials. Addition...

Many fabrication processes for polymeric objects include melt extrusion, in which the molten polymer is conveyed by a ram or a screw and the melt is then forced through a shaping die in continuous processing or into a mold for the manufacture of discrete molded parts. The properties of the fabricated solid object, including morphology developed during cooling and solidification, depend in part ...

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