In this paper the carbon distribution in the carburized layer of 20CrMnTi steel was studied. The relationship between the depth of a carburized layer and the surface carbon distribution was established. Eddy current t...In this paper the carbon distribution in the carburized layer of 20CrMnTi steel was studied. The relationship between the depth of a carburized layer and the surface carbon distribution was established. Eddy current testing system of the case depth of this carburized steel was built by using ANSYS software as second development platform.展开更多
Optical vortices as topological objects exist ubiquitously in nature.In this paper,by making use of the Duan's topological current theory,we investigate the topology in the closed and knotted optical vortices.The ...Optical vortices as topological objects exist ubiquitously in nature.In this paper,by making use of the Duan's topological current theory,we investigate the topology in the closed and knotted optical vortices.The topological inner structure of the optical vortices are obtained,and the linking of the knotted optical vortices is also given.展开更多
One of the challenges in predicting the dynamic response of deepwater risers under vortex-induced vibration （VIV） is that it runs short of believable fluid loading model. Moreover, the hydrodynamic loading is also d...One of the challenges in predicting the dynamic response of deepwater risers under vortex-induced vibration （VIV） is that it runs short of believable fluid loading model. Moreover, the hydrodynamic loading is also difficult to be measured directly in the VIV experiments without disturbing the fluid field. In the present work, by means of a finite element analysis method based on the experimental data of the response displacements, the total instantaneous distributions of hydrodynamic forces together with the hydrodynamic coefficients on the riser model with large aspect ratio （length/ddiameter） of 1750 are achieved. The steady current speeds considered in the experiments of this work are ranging from 0.15 rn/s to 0.60 m/s, giving the Reynolds Number between 2400 and 9600. The hydrodynamic coefficients are evaluated at the fundamental frequency and in the higher order frequency components for both in-line and cross-flow directions. It is found that the Root-Mean Squared hydrodynamic forces of the higher order response frequency are larger than those of the fundamental response frequency. Negative lift or drag coefficients are found in the numerical results which is equivalent to the effect of fluid damping.展开更多
文摘In this paper the carbon distribution in the carburized layer of 20CrMnTi steel was studied. The relationship between the depth of a carburized layer and the surface carbon distribution was established. Eddy current testing system of the case depth of this carburized steel was built by using ANSYS software as second development platform.
基金supported by National Natural Science Foundation of China
文摘Optical vortices as topological objects exist ubiquitously in nature.In this paper,by making use of the Duan's topological current theory,we investigate the topology in the closed and knotted optical vortices.The topological inner structure of the optical vortices are obtained,and the linking of the knotted optical vortices is also given.
基金supported by the 863 Program of China (Grant No. 2006AA09A103)partially supported by the National Natural Science Foundation of China (Grant No. 50921001)the open fund from the State Key Laboratory of Coastal and Offshore Engineering (Grant No. LP0904)
文摘One of the challenges in predicting the dynamic response of deepwater risers under vortex-induced vibration （VIV） is that it runs short of believable fluid loading model. Moreover, the hydrodynamic loading is also difficult to be measured directly in the VIV experiments without disturbing the fluid field. In the present work, by means of a finite element analysis method based on the experimental data of the response displacements, the total instantaneous distributions of hydrodynamic forces together with the hydrodynamic coefficients on the riser model with large aspect ratio （length/ddiameter） of 1750 are achieved. The steady current speeds considered in the experiments of this work are ranging from 0.15 rn/s to 0.60 m/s, giving the Reynolds Number between 2400 and 9600. The hydrodynamic coefficients are evaluated at the fundamental frequency and in the higher order frequency components for both in-line and cross-flow directions. It is found that the Root-Mean Squared hydrodynamic forces of the higher order response frequency are larger than those of the fundamental response frequency. Negative lift or drag coefficients are found in the numerical results which is equivalent to the effect of fluid damping.
