The fatigue behaviour of longitudinal stiffeners of oil tankers and container ships, subjected to dynamic loads, is analysed. The following dynamic load components are considered: hull girder vertical wave bending moment, alone and combined with the horizontal wave bending moment, hydrodynamic pressure and inertial forces caused by cargo acceleration.
The spectral method was selected to calculate the fatigue damage, based on S—N curves and Miner's rule. Following this approach, the fatigue damage may be calculated as a function of a stress parameter Ωp, which represents the cumulative effect of wave induced loads in the unit of time and incorporates the combined effects of stress level and its occurring frequency.
Simple formulas for Ωp of oil tankers and container ships are given, obtained from the results of hydrodynamic analyses performed on several ships, in different wave environments.
Several examples show the applicability of the methods to real ship structures. The method, however, still needs to be calibrated because of the simplifying hypotheses introduced in the loading conditions. 相似文献
In this paper, we describe a system that locates and tracks the eyes of a driver. The purpose of such a system is to perform detection of driver fatigue. By mounting a small camera inside the car, we can monitor the face of the driver and look for eye movements which indicate that the driver is no longer in condition to drive. In such a case, a warning signal should be issued. This paper describes how to find and track the eyes. We also describe a method that can determine if the eyes are open or closed. The primary criterion for this system is that it must be highly non-intrusive. The system must also operate regardless of the texture and the color of the face. It must also be able to handle changing conditions such as changes in light, shadows, reflections, etc. Initial experimental results are very promising even when the driver moves his/her head in a way such that the camera does not have a frontal view of the driver’s face. 相似文献