AIM：To select the optimal edge detection methods to identify the corneal surface,and compare three fitting curve equations with Matlab software. METHODS：Fifteen subjects were recruited. The corneal images from optic...AIM：To select the optimal edge detection methods to identify the corneal surface,and compare three fitting curve equations with Matlab software. METHODS：Fifteen subjects were recruited. The corneal images from optical coherence tomography（OCT）were imported into Matlab software. Five edge detection methods（Canny,Log,Prewitt,Roberts,Sobel）were used to identify the corneal surface. Then two manual identifying methods（ginput and getpts）were applied to identify the edge coordinates respectively. The differences among these methods were compared. Binomial curve（y=Ax2＋Bx＋C）,Polynomial curve [p（x）=p1xn＋p2x（n-1）＋....＋pnx＋pn＋1] and Conic section（Ax2＋Bxy＋Cy2＋Dx＋Ey＋F=0）were used for curve fitting the corneal surface respectively. The relative merits among three fitting curves were analyzed. Finally,the eccentricity（e）obtained by corneal topography and conic section were compared with paired t-test. RESULTS：Five edge detection algorithms all had continuous coordinates which indicated the edge of the corneal surface. The ordinates of manual identifying were close to the inside of the actual edges. Binomial curve was greatly affected by tilt angle. Polynomial curve was lack of geometrical properties and unstable. Conic section could calculate the tilted symmetry axis,eccentricity,circle center,etc. There were no significant differences between ＇e＇ values by corneal topography and conic section（t=0.9143,P=0.3760 〉0.05）.CONCLUSION：It is feasible to simulate the corneal surface with mathematical curve with Matlab software. Edge detection has better repeatability and higher efficiency. The manual identifying approach is an indispensable complement for detection. Polynomial and conic section are both the alternative methods for corneal curve fitting. Conic curve was the optimal choice based on the specific geometrical properties.展开更多
Nd-rich phase plays an important role in the magnetic properties of sintered NdFeB alloy. The proportion of Nd-rich phase to all the other phases was calculated by using MATLAB 6.5 software. Especially, post-sintered ...Nd-rich phase plays an important role in the magnetic properties of sintered NdFeB alloy. The proportion of Nd-rich phase to all the other phases was calculated by using MATLAB 6.5 software. Especially, post-sintered alloy, post-high-temperature tempered alloy and post-high and low-temperature tempered alloy were analyzed. It was found that the proportion of Nd-rich phase in the three alloys based on SEM (scanning electron microscope) images was about 8.22%, 8.03% and 8.00%, respectively.展开更多
详细介绍了电力系统暂态仿真软件的开发原理,并在此基础上开发了一个基于Matlab/Simulink的电力系统仿真工具箱(power system simulation toolbox,PSST)。该仿真工具箱目前可完成潮流计算,小干扰稳定分析和动态时域仿真等方面的分析和研...详细介绍了电力系统暂态仿真软件的开发原理,并在此基础上开发了一个基于Matlab/Simulink的电力系统仿真工具箱(power system simulation toolbox,PSST)。该仿真工具箱目前可完成潮流计算,小干扰稳定分析和动态时域仿真等方面的分析和研究,具有使用方便、可扩展性强等优点,克服了常规的大型商业化软件难以添加新模块的缺点,能够无缝地以Simulink模块的形式添加自定义新模块。此外,还可以根据实际仿真精度的要求灵活选用合适的Simulink求解器进行仿真求解而无需修改仿真模型。通过对同一个新英格兰系统进行时域仿真,将PSST和电力系统工具箱(power system toolbox,PST)的仿真结果进行了分析对比,验证PSST仿真结果的有效性和准确性。最后以静止无功补偿器的广域附加阻尼控制器的设计为例阐述了用PSST设计控制器的基本原理和方法。可以看出,PSST非常适合用于电力系统控制方面的研究。展开更多
基金Supported by the National Natural Science Foundation of China(No.81400428)Science and Technology Commission of Shanghai Municipality(No.134119b1600)
文摘AIM：To select the optimal edge detection methods to identify the corneal surface,and compare three fitting curve equations with Matlab software. METHODS：Fifteen subjects were recruited. The corneal images from optical coherence tomography（OCT）were imported into Matlab software. Five edge detection methods（Canny,Log,Prewitt,Roberts,Sobel）were used to identify the corneal surface. Then two manual identifying methods（ginput and getpts）were applied to identify the edge coordinates respectively. The differences among these methods were compared. Binomial curve（y=Ax2＋Bx＋C）,Polynomial curve [p（x）=p1xn＋p2x（n-1）＋....＋pnx＋pn＋1] and Conic section（Ax2＋Bxy＋Cy2＋Dx＋Ey＋F=0）were used for curve fitting the corneal surface respectively. The relative merits among three fitting curves were analyzed. Finally,the eccentricity（e）obtained by corneal topography and conic section were compared with paired t-test. RESULTS：Five edge detection algorithms all had continuous coordinates which indicated the edge of the corneal surface. The ordinates of manual identifying were close to the inside of the actual edges. Binomial curve was greatly affected by tilt angle. Polynomial curve was lack of geometrical properties and unstable. Conic section could calculate the tilted symmetry axis,eccentricity,circle center,etc. There were no significant differences between ＇e＇ values by corneal topography and conic section（t=0.9143,P=0.3760 〉0.05）.CONCLUSION：It is feasible to simulate the corneal surface with mathematical curve with Matlab software. Edge detection has better repeatability and higher efficiency. The manual identifying approach is an indispensable complement for detection. Polynomial and conic section are both the alternative methods for corneal curve fitting. Conic curve was the optimal choice based on the specific geometrical properties.
基金Funded by the Key Project of Sichan Science Department (2012 JY0045, 2011SZZ029)Key Project of Sichan Education Department (10ZA060, 11ZA161)+1 种基金Key Project of Mianyang Municipal Science and Technology Bureau (10Y002-4)Special Project of MianYang Normal University (2011C02)
文摘Nd-rich phase plays an important role in the magnetic properties of sintered NdFeB alloy. The proportion of Nd-rich phase to all the other phases was calculated by using MATLAB 6.5 software. Especially, post-sintered alloy, post-high-temperature tempered alloy and post-high and low-temperature tempered alloy were analyzed. It was found that the proportion of Nd-rich phase in the three alloys based on SEM (scanning electron microscope) images was about 8.22%, 8.03% and 8.00%, respectively.
文摘详细介绍了电力系统暂态仿真软件的开发原理,并在此基础上开发了一个基于Matlab/Simulink的电力系统仿真工具箱(power system simulation toolbox,PSST)。该仿真工具箱目前可完成潮流计算,小干扰稳定分析和动态时域仿真等方面的分析和研究,具有使用方便、可扩展性强等优点,克服了常规的大型商业化软件难以添加新模块的缺点,能够无缝地以Simulink模块的形式添加自定义新模块。此外,还可以根据实际仿真精度的要求灵活选用合适的Simulink求解器进行仿真求解而无需修改仿真模型。通过对同一个新英格兰系统进行时域仿真,将PSST和电力系统工具箱(power system toolbox,PST)的仿真结果进行了分析对比,验证PSST仿真结果的有效性和准确性。最后以静止无功补偿器的广域附加阻尼控制器的设计为例阐述了用PSST设计控制器的基本原理和方法。可以看出,PSST非常适合用于电力系统控制方面的研究。
