The prediction of central bursting defects in the rod extrusion process through conical dies using the upper bound analysisis investigated. A kinematically admissible velocity field, including the radial and angular v...The prediction of central bursting defects in the rod extrusion process through conical dies using the upper bound analysisis investigated. A kinematically admissible velocity field, including the radial and angular velocity components, is proposed. A newcriterion is presented to predict the occurrence of the central bursting defects. Parameter bobt, which represents the risk probability ofcracking, is proposed. It is calculated using the shape of the boundary at the entrance by minimizing the total power dissipationduring the extrusion process. When bobt is equal to or greater than bcr, central bursting occurs. Furthermore, the quantitativerelationships between central bursting defects and process parameters （semi die angle, reduction in area and frictional factor） arestudied. The results show that the central bursting defects are affected primarily by the reduction in area and the friction factor. Thepresented criterion is verified by comparing with the FEM simulation data and the results of the published paper.展开更多
AIM: To investigate the characteristics of postoperative central visual field defect(cVFD) in patients with macular hole(MH).METHODS: Eighteen eyes from 18 MH patients were involved in this retrospective study which r...AIM: To investigate the characteristics of postoperative central visual field defect(cVFD) in patients with macular hole(MH).METHODS: Eighteen eyes from 18 MH patients were involved in this retrospective study which reviewed square root of loss variance(sLV) and mean defect(MD) of the visual field test in all subjects. The relationship between cVFD and MH stage, as well as the postoperative ellipsoid zone disruption were evaluated using Spearman's correlation test. RESULTS: Our analysis determined Spearman coefficient is 0.705 for the correlation between sLV and MH stage(P<0.01), 0.877 for the correlation between sLV and postoperative ellipsoid zone disruption(P<0.01) and 0.721 for the correlation between MD and postoperative ellipsoid zone disruption(P<0.01). A significant relationship was also detected between postoperative ellipsoid zone disruption and MH stage(r=0.470, P<0.05). Univariate regression analysis indicated that sLV and MD were associated with postoperative ellipsoid zone disruption(P<0.01, P<0.01, respectively). CONCLUSION: Postoperative cVFD is highly correlated with MH stage and postoperative ellipsoid zone disruption in patients with MH.展开更多
文摘The prediction of central bursting defects in the rod extrusion process through conical dies using the upper bound analysisis investigated. A kinematically admissible velocity field, including the radial and angular velocity components, is proposed. A newcriterion is presented to predict the occurrence of the central bursting defects. Parameter bobt, which represents the risk probability ofcracking, is proposed. It is calculated using the shape of the boundary at the entrance by minimizing the total power dissipationduring the extrusion process. When bobt is equal to or greater than bcr, central bursting occurs. Furthermore, the quantitativerelationships between central bursting defects and process parameters （semi die angle, reduction in area and frictional factor） arestudied. The results show that the central bursting defects are affected primarily by the reduction in area and the friction factor. Thepresented criterion is verified by comparing with the FEM simulation data and the results of the published paper.
基金Supported by National Natural Science Foundation of China(No.81670865 No.81500743)Natural Science Foundation of Tianjin(No.16JCQNJC13000)
文摘AIM: To investigate the characteristics of postoperative central visual field defect(cVFD) in patients with macular hole(MH).METHODS: Eighteen eyes from 18 MH patients were involved in this retrospective study which reviewed square root of loss variance(sLV) and mean defect(MD) of the visual field test in all subjects. The relationship between cVFD and MH stage, as well as the postoperative ellipsoid zone disruption were evaluated using Spearman's correlation test. RESULTS: Our analysis determined Spearman coefficient is 0.705 for the correlation between sLV and MH stage(P<0.01), 0.877 for the correlation between sLV and postoperative ellipsoid zone disruption(P<0.01) and 0.721 for the correlation between MD and postoperative ellipsoid zone disruption(P<0.01). A significant relationship was also detected between postoperative ellipsoid zone disruption and MH stage(r=0.470, P<0.05). Univariate regression analysis indicated that sLV and MD were associated with postoperative ellipsoid zone disruption(P<0.01, P<0.01, respectively). CONCLUSION: Postoperative cVFD is highly correlated with MH stage and postoperative ellipsoid zone disruption in patients with MH.
