this paper describes a contra-rotating propeller (crp) system to calculate the hydrodynamic characteristics and then design the optimum operational condition to be installed on two different large bulk carriers and vlcc. the method is based on boundary element method (bem) to obtain the hydrodynamic performance of any complicated configuration such as crp system, and then the optimum propeller ...

Shipwrecks around the world contain unknown volumes of hazardous substances which, if discharged, could harm the marine environment. Shipwrecks can deteriorate for a number of reasons, including corrosion and physical impact from trawling and other activities, and the probability of a leakage increases with time. Before deciding on possible mitigation measures, there are currently few comprehen...

Noticeable variation was observed in a number of morphological characters in the Glycyrrhiza specimens in various habitats in north of Iran. To study these variations, two taxa related to the Hyrcanian region from all four known taxa of this genus in Iran, including Glycyrrhiza echinata, and G. glabra var. glabra were studied by numerical taxonomy using morphological characters in three provinc...

In this paper, an effective numerical method is introduced for the treatment of nonlinear two-dimensional Volterra-Fredholm integro-differential equations. Here, we use the so-called two-dimensional block-pulse functions.First, the two-dimensional block-pulse operational matrix of integration and differentiation has been presented. Then, by using this matrices, the nonlinear two-dimensional Vol...