Sharif Digital Repository

Propylene, as one of the most important raw materials of petrochemical industries, is produced through different methods. One of the major methods is propane dehydrogenation. This reaction is endothermic and many by-products will be produced in high temperature. Therefore catalytic dehydrogenation is preferred. Reduction in catalyst's activity and too many side reactions are the most important problems. Coke formation is the most effective reason of deactivation. Main source of coke is propylene. Experiments show that very small amount of water presence within reaction can reduce rate of coke formation. Water content growth does not always increase activity. If water be more than optimum... 

The closed-form formulation of MDCEV has become popular in past years, as it accounts for satiation effects through a novel consumption-based utility structure. The model, however, suffers from an “empirical identification” problem. The problem is mainly due to entangled roles of two model parameters in capturing satiation effects. Thus far, the best known solution to the problem is fixing either or both of the parameters to pre-defined values and estimate a restricted satiation profile. This paper, presents a new hybrid optimization algorithm (named HEMPME) to eliminate the need for imposing such restrictions, and disentangle the two effects through estimating a “mixed profile” model.... 

In this study, the polysulfon ultrafilteration membranes were prepared and applied to concentrate the Lipase enzymes produced in the laboratory and the commercial enzymes of Novozymes Company. Using Design Expert software. The effect of membrane preparation conditions including polysulfone and polyvinylpyrrolidone concentration and the solvent type were investigated. The prepared membranes were characterized by measuring of distilled water flux, enzyme liquor flux, and enzyme activity in permeate and the Retentate flows. The results showed that increasing of polysulfone concentration reduced the flux of distilled water and enzyme activity in permeate and enhanced the enzyme activity in the... 

Neural systems are the threshold ones. It means if the electrical potential passed through a specific amount then they could spike and cause the activity of other cells. The models that really mimic the action of neurons are usually complicated and are not suitable when you put them on a network to study the collective behavior of the neurons. Simple threshold models have been designed for such purposes. One on most studied ones is the ’integrate and fire’ model, in which cells integrate the inputs until the threshold potential and then spike. usually, a network of these objects are simulated and different properties of such network are investigated.However, this model has some shortcomings...