background: rivers and streams are important sources of surface waters. water quality of these resources depends on many factors including hydrologic, physicochemical and biological factors. these resources are important in terms of social, economic and political development.. zayanderood river is the only river in central basin of iran that has permanent fresh water. this river has an importan...

This paper is on the elasto-plastic analysis of plane stress problems. A five-parameter yield surface is presented. This yield criterion uses associate flow along with mixed hardening rule. The analytical formulations are written and related computer program for non-linear analysis is prepared. Finally, based on the formulations, numerical examples are solved.

In this paper, the profile of surfaces machined using end mills with flat and ball end tools in modeled. The real kinematics of the tool motion, the static deflection and the run out of the tool are included in the model. The cutting forces are calculated using a semi-empirical method based on orthogonal to oblique conversion of cutting coefficients. The thickness of the uncut chip is used as t...

In this paper, a new guidance method for surface to surface ballistic missiles without mandatory engine cut-off will be presented. The complexity of solid fuel engine cut-off demands a comprehensive method for guiding these missiles. In the method presented in this paper, a certain guidance law is applied such that by transmitting appropriate commands to the control system, by changing the miss...

2,4-dinitrophenylhydrazanomethylphenol (dnphmp) was immobilized onto silicate rice husk ash to form a heterogeneous catalyst denoted as rhdnph. the elemental and edx analysis of rhdnph showed the nitrogen is incorporated into silica. the rhdnph had 154.6 m2g-1 as a specific surface area. the ft-ir clearly showed the appearance of –nh and c=n absorption band at the expected range. the tga curve ...

to enhance the understanding of the impact of obstacle buildings on pollution transportationand dispersion in the atmospheric boundary layer, it is necessary to know the atmospheric flow characteristics over terrains. wind flow characteristics in a boundary layer over a step-shaped cliff topography model with rough and smooth surfaces were studied numerically using computational fluid dynamics ...