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...

The emission rate measurements of H2S into the atmosphere from coastal marine sediments were made by the use of an emission flux reactor (chamber) technique under deaerated (gaseous N2) and aerated (ambient air) conditions. The emission rates of H2S varied over a wide range (>0.05 to < 100 gS m-2 yr I ) . The emission of H2S was inversely related to the stage of tidal hydrology, with incoming a...

As a new type of biological treatment process, membrane aerated biofilm reactors (MABRs), which have received extensive attention and research in recent years, could reduce energy consumption by 70% compared to the traditional activated sludge process. The MABR system uses bubble-free aeration material as carrier, counter-diffusion mechanism oxygen pollutants enables ammonium oxidizing bacteria...

A naphtha catalytic reforming unit with four reactors in series is analyzed. A physical model is proposed to describe the catalytic reforming radial flow reactor. Kinetics and thermodynamics equations are selected to describe the naphtha catalytic reforming reactions characteristics based on idealizing the complex naphtha mixture by representing the paraffin, naphthene, and aromatic groups by s...

the problems of land degradation and soil loss are among the major problems of watersheds in iran. for erosion andsediment estimation one can use statistical and empirical methods. for doing this, land unit map and the map of effectivefactors should be prepared. for erosion and sediment estimation one can use statistical and empirical methods. however,these empirical methods are usually time co...

The paper is devoted to solution of some problems in nuclear power station generating unit intellectual control systems using genetic algorithms on the basis of control system model development, optimizations methods of their direct quality indices and improved integral quadratic estimates. Some mathematical vector models were obtained for control system multicriterion quality indices with due ...

Gamma spectroscopy was used for determination of radionuclides in sediment cores from the continental shelf off NW Africa to provide age control of the sediment record used for a study of aridification of the Sahel zone. Pb, Ra and Cs were measured in the upper part of a gravity core and the associated multicorer and used for aligning these cores. This provided information about the amount of s...