Simultaneous reduction of the project cost and its performing duration was an essential necessity in today's rival environment. Quality, the effective parameter of optimization, as an effective indicator was attended by the costumers. So, due to the asymmetry between the two factors-Time and Cost and the factor of Quality it was essential to make the project decision in the best balanced conditions between the three factors. Project scheduling ,increasing the project quality level and sources

more »

... mitations were unavoidable in today's environment. The accession of popularity of the project delivery system had replaced the customers. The contractors had more wariness about their benefits. The wariness about losing the opportunities, performing earlier finishing with the highest quality and reducing the cost. In this research a new model named STHD was introduced. This mechanism was inspired by the dolphin's natural behavior and living manner in hunting as clever creatures in hunting and reproduction. In this article a sample problem in discrete position and close to reality was estimated. And showed its flexibility conclusions according to ANOVA method. The high difference of this method in comparison to the others showed the most optimization, practicality and occurrence in decision making with more than 70% optimization.