A theoretical explanation about the variation of the area of the reflow zone and the vertical entrainment velocity along the height of the regular isosceles bluff body is made from both the instantaneous and averaging viewpoints.

According to the requirements of social network structure analysis,the group analysis method based on regular equivalence group and the force-directed layout algorithm based on group and role analysis under this ontology model have been presented.

The sum of the directed distances from any point in space to equicrural tetrahedrom s four planes is a definite number.

A simplified way of calculation based on the concept of equivalent regular wave was proposed for calculation of the combined stressinduced damage to the longitudinal structures during overal longitudinal bending of ship.

On certaim conditions, the anomalous bodies are or approach the regular body, so the formulae of gravitational vertical derivative of sphere, semisphere, cylinder, cone and cuboid are presented and introduced.