Purpose:To investigate a quantitative method to measure decentration distance(DD) and analyze the DD of four kinds of intraocular lenses (IOLs).Methods:The pseudophakic eye photos were taken under the slit lamp after ...Purpose:To investigate a quantitative method to measure decentration distance(DD) and analyze the DD of four kinds of intraocular lenses (IOLs).Methods:The pseudophakic eye photos were taken under the slit lamp after the IOLs were implanted a year or longer. Then the images were inputted into a computer and the Photoshop software was applied to analyze the DD. Four kinds of IOLs were analyzed, including AcrySof MA60BM (11 eyes), Allergan SA40N (11 eyes), AcrySof SA60AT/SA30AL (5 eyes), Corneal Quattro (4 eyes).Results:The mean value of DD was (0.264 3±0.157 4)mm in the AcrySof MA60BM group,(0.353 6±0.171 9)mm in the Array SA40N group,(0.309 9±0.152 9)mm in the SA60AT/SA30AL group, and (0.326 1±0.187 7)mm in the Quattro group. The difference of the DD values among these 4 kinds of IOLs had no statistic significance (F=0.506,P=0.681) and the values were not equal to zero (t=10.508, P < 0.001).Conclusion:The Photoshop method is a simple and efficient way for DD analysis. The modern foldable posterior-chamber-IOLs have good centration performances when implanted into the capsular bags. Eye Science 2004;20:48-51.展开更多
A pintle injector is advantageous for throttling a liquid rocket engine and reducing engine weight. This study ex- plores the effects of momentum ratio and Weber number at various injection conditions on spray charact...A pintle injector is advantageous for throttling a liquid rocket engine and reducing engine weight. This study ex- plores the effects of momentum ratio and Weber number at various injection conditions on spray characteristics of the pintle injector for liquid-gas propellants. A liquid sheet is injected from a center pintle nozzle and it is broken by a gas jet from an annular gap. The pressure drops of propellants, and the pintle opening distance were consi- dered as control variables; using 0.1 -1.0 as a bar for the pressure drop of the liquid injection, a 0.01-4）.2 bar for the pressure drop of gas jet and a 0.2 - 1.0 mm for the pintle opening distance. The discharge coefficient was de- creased linearly before the pintle opening distance of 0.75 mm and then, the coefficient was slightly increased. Spray images were captured by a CMOS camera with high resolution. Then, the shadow and reflected images were analyzed. Spray distributions were measured by a pattemator with an axial distance of 50 mm from a pintle tip. Finally, the spray half angles had an exponentially decreasing correlation as a momentum ratio divided by the Weber number. Also, the spray half angles from the spray distribution were underestimated compared to those measured from the captured images.展开更多
The valuation of the hydraulic performance of a centrifugal pump with pre-whirl regulation of the inlet guide vanes was studied experimentally by varying the pre-whirl angle from -60° to 60° with distances b...The valuation of the hydraulic performance of a centrifugal pump with pre-whirl regulation of the inlet guide vanes was studied experimentally by varying the pre-whirl angle from -60° to 60° with distances between the inlet guide vanes and the impeller inlet of 280 mm, 380 mm and 460 mm. The efficiency-flow curves and the characteristic curves were obtained for the pump for various operation conditions. The experiment results demonstrated that the pre-whirl regulation widened the high efficiency zone and improved the hydraulic performance for off-design conditions with the proper pre-whirl angle. The axial distance between the inlet guide vanes and the impeller inlet influenced the pre-whirl regulation effect of the inlet guide vanes with the best pre-whirl regulation effect obtained for an axial distance of 380 mm. These results showed that an appropriate axial distance between the inlet guide vanes and the impeller inlet can improve the fluid flow at the impeller entrance with pre-whirl regulation for centrifugal pumps.展开更多
Objective： To get morphologic parameters of Chinese adults through observation and measurement on axial laminas, to evaluate the feasibility of placing axial laminar screws and to introduce the technique. Methods： ...Objective： To get morphologic parameters of Chinese adults through observation and measurement on axial laminas, to evaluate the feasibility of placing axial laminar screws and to introduce the technique. Methods： Relative parameters of 28 sets of fresh Chinese adults＇ axial specimens, including distance from the superior and inferior entry points of axial laminar screws to the superior margins of axial laminas, superior, middle, inferior thickness and height of the axial laminas, length and angle of the axial laminar screw trajectories, distance from the entry points of axial laminar screws to the transverse foramen and central points of the inferior articular process, were measured with a digital caliper and a goniometer. Data were statistically analyzed. Results： Averagely, distance from the superior and inferior entry points of axial laminar screws to the superior margins of axial laminas was 5 mm and 9 mm, superior, middle, inferior thickness and the height of the axial laminas were 3.2 mm, 6.7 mm, 5.5 mm and 12.8 mm respectively, and the length of the superior and inferior axial laminar screw trajectories was 26.2 mm and 25.5 ram, respectively. Conclusions： It is feasible and reliable to apply posterior laminar screw fixation techniques to the axes of Chinese adults. Also the C2 laminar screw fixation technique can be taken as a supplementary to conventional posterior screw fixations of C2.展开更多
文摘Purpose:To investigate a quantitative method to measure decentration distance(DD) and analyze the DD of four kinds of intraocular lenses (IOLs).Methods:The pseudophakic eye photos were taken under the slit lamp after the IOLs were implanted a year or longer. Then the images were inputted into a computer and the Photoshop software was applied to analyze the DD. Four kinds of IOLs were analyzed, including AcrySof MA60BM (11 eyes), Allergan SA40N (11 eyes), AcrySof SA60AT/SA30AL (5 eyes), Corneal Quattro (4 eyes).Results:The mean value of DD was (0.264 3±0.157 4)mm in the AcrySof MA60BM group,(0.353 6±0.171 9)mm in the Array SA40N group,(0.309 9±0.152 9)mm in the SA60AT/SA30AL group, and (0.326 1±0.187 7)mm in the Quattro group. The difference of the DD values among these 4 kinds of IOLs had no statistic significance (F=0.506,P=0.681) and the values were not equal to zero (t=10.508, P < 0.001).Conclusion:The Photoshop method is a simple and efficient way for DD analysis. The modern foldable posterior-chamber-IOLs have good centration performances when implanted into the capsular bags. Eye Science 2004;20:48-51.
基金supported by Advanced Research Center Program(NRF-2013R1A5A1073861)through the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIP)contracted through Advanced Space Propulsion Research Center at Seoul National University
文摘A pintle injector is advantageous for throttling a liquid rocket engine and reducing engine weight. This study ex- plores the effects of momentum ratio and Weber number at various injection conditions on spray characteristics of the pintle injector for liquid-gas propellants. A liquid sheet is injected from a center pintle nozzle and it is broken by a gas jet from an annular gap. The pressure drops of propellants, and the pintle opening distance were consi- dered as control variables; using 0.1 -1.0 as a bar for the pressure drop of the liquid injection, a 0.01-4）.2 bar for the pressure drop of gas jet and a 0.2 - 1.0 mm for the pintle opening distance. The discharge coefficient was de- creased linearly before the pintle opening distance of 0.75 mm and then, the coefficient was slightly increased. Spray images were captured by a CMOS camera with high resolution. Then, the shadow and reflected images were analyzed. Spray distributions were measured by a pattemator with an axial distance of 50 mm from a pintle tip. Finally, the spray half angles had an exponentially decreasing correlation as a momentum ratio divided by the Weber number. Also, the spray half angles from the spray distribution were underestimated compared to those measured from the captured images.
基金supported by the National Natural Science Foundation of China (Grant No. 51176088)the National Basic Research Program of China ("973" Project) (Grant No. 2009CB724304) the General Financial Grant from the China Postdoctoral Science Foundation (Grant No. 2011M500315)
文摘The valuation of the hydraulic performance of a centrifugal pump with pre-whirl regulation of the inlet guide vanes was studied experimentally by varying the pre-whirl angle from -60° to 60° with distances between the inlet guide vanes and the impeller inlet of 280 mm, 380 mm and 460 mm. The efficiency-flow curves and the characteristic curves were obtained for the pump for various operation conditions. The experiment results demonstrated that the pre-whirl regulation widened the high efficiency zone and improved the hydraulic performance for off-design conditions with the proper pre-whirl angle. The axial distance between the inlet guide vanes and the impeller inlet influenced the pre-whirl regulation effect of the inlet guide vanes with the best pre-whirl regulation effect obtained for an axial distance of 380 mm. These results showed that an appropriate axial distance between the inlet guide vanes and the impeller inlet can improve the fluid flow at the impeller entrance with pre-whirl regulation for centrifugal pumps.
文摘Objective： To get morphologic parameters of Chinese adults through observation and measurement on axial laminas, to evaluate the feasibility of placing axial laminar screws and to introduce the technique. Methods： Relative parameters of 28 sets of fresh Chinese adults＇ axial specimens, including distance from the superior and inferior entry points of axial laminar screws to the superior margins of axial laminas, superior, middle, inferior thickness and height of the axial laminas, length and angle of the axial laminar screw trajectories, distance from the entry points of axial laminar screws to the transverse foramen and central points of the inferior articular process, were measured with a digital caliper and a goniometer. Data were statistically analyzed. Results： Averagely, distance from the superior and inferior entry points of axial laminar screws to the superior margins of axial laminas was 5 mm and 9 mm, superior, middle, inferior thickness and the height of the axial laminas were 3.2 mm, 6.7 mm, 5.5 mm and 12.8 mm respectively, and the length of the superior and inferior axial laminar screw trajectories was 26.2 mm and 25.5 ram, respectively. Conclusions： It is feasible and reliable to apply posterior laminar screw fixation techniques to the axes of Chinese adults. Also the C2 laminar screw fixation technique can be taken as a supplementary to conventional posterior screw fixations of C2.
