abstract irregular extraction from agricultural wells around parishan lake, moreover fall of groundwater surface and water salty, would affect the level of lake water and move lake water into wells. in this study we have evaluated the externalities of extraction from agricultural wells around the lake. therefore feedback effect is considered between agricultural activity around the lake and lev...

Brown seaweeds are abundant in Portuguese coastline and represent an almost unexploited marine economic resource. One of the most common species, easily available for harvesting in the northwest coast, is Saccorhiza polyschides grows in the lowest shore and costal rocky reefs. It is almost exclusively used by local farmers as natural fertilizer, but contains a substantial amount of valuable com...

The aim of this paper is to extend the study done by [5]. Here, we will analyze two mathematical models associated to some economic growth processes with endogenous population depending on the current fertility. The first model is a version of the Ramsey model in continuous and infinite time with the Cobb-Douglas production function. In the second model we consider the AK production function. T...

Economic Order Quantity (EOQ) model has been extended. We formulate EOQ model as a calculus of variations. This new extended problem is a simple optimal control problem with an unknown initial state. By solving this problem we generalize EOQ formula [1].