underbalanced drilling as multiphase flow is done in oil drilling operation in low pressure reservoir or highly depleted mature reservoir. correct determination of the pressure loss of three phase fluids in drilling annulus is essential in determination of hydraulic horsepower requirements during drilling operations. in this paper the pressure loss of solid-gas-liquid three-phase fluids flow in...

BACKGROUND The complexity of reactions and kinetic is the current problem of photodegradation processes. Recently, artificial neural networks have been widely used to solve the problems because of their reliable, robust, and salient characteristics in capturing the non-linear relationships between variables in complex systems. In this study, an artificial neural network was applied for modeling...

there is a lack of accurate and correct information about erosion in iran. moreover, there is a big difference between measurements and estimations. sediment is also an important environmental problem which pollutes water physically and chemically and therefore, sediment problem is usually studied as environmental problems. estimation of sediment yield of drainage basins is important for preven...

climate change is found to be the most important global issue in the 21st century, so to monitor its trend is of great importance. atmospheric general circulation models because of their large scale computational grid are not able to predict climatic parameters on a point scale, so small scale methods should be adapted. among downscaling methods, statistical methods are used as they are easy to...

in recent decades, the developments of artificial intelligence to predict hydrologic models have been widely used. in this study, the ability of artificial neural network(ann) models for modeling and predict the biological oxygen demand (bod) is located on the karun river in west iran were evaluated. to improve the simulation results, wavelet analysis was used as a hybrid model. bod index month...

the increasing use of nitrogen fertilizers due to high dynamics of nitrate in the soil would be a serious threat to groundwater, and therefore, to thuman health. this study is aimed to investigate the disperdivity values of nitrate in the coarse, medium and fine sandy soils in the short travel distance of 20, 40 and 80 cm in vitro using the hydrus-1d model. for this purpose, pure potassium nitr...