A semi-length focal plane detecting system for heavy ions has been built onthe Beijing Q3D magnetic spectrometer and tested by <sup>12</sup>C+<sup>197</sup>Au,<sup>16</sup>O+<sup...A semi-length focal plane detecting system for heavy ions has been built onthe Beijing Q3D magnetic spectrometer and tested by <sup>12</sup>C+<sup>197</sup>Au,<sup>16</sup>O+<sup>150</sup>Sm,and <sup>18</sup>O-<sup>156</sup>Gd reactions.The intrinsic resolutions of position and angle were 1.1 mmand 0.8°,respectively.The resolutions of energy loss ΔE,residual energy E<sub>R</sub> and totalenergy E<sub>T</sub> obtained were 3.0%,1.4% and 0.9%.respectively,after a special method ofdata processing was adopted.The achievable mass resolution is estimated to be about1.0% after necessary corrections for some signals concerned.Discussion aboul the edgeeffect of the detectors of this type is given too.展开更多
由于传统基于梯度的方形边缘检测算子包含边缘方向过少(一般为2个或4个方向),因此无法从多分辨率角度检测边缘,进而会丢失其他方向的边缘信息。针对上述问题,提出一种具有多尺度、多分辨率特性的边缘检测算子,称为可变局部边缘模式(Vari...由于传统基于梯度的方形边缘检测算子包含边缘方向过少(一般为2个或4个方向),因此无法从多分辨率角度检测边缘,进而会丢失其他方向的边缘信息。针对上述问题,提出一种具有多尺度、多分辨率特性的边缘检测算子,称为可变局部边缘模式(Varied Local Edge Pattern,VLEP)算子,并用来提取图像边缘信息。算法主要思路包括,将图像经过高斯滤波器平滑,使用一组或多组VLEP算子与滤波后的图像进行卷积,得到边缘强度,从而获得边缘梯度值,最后设置适当的梯度阈值,对梯度图像进行二值化处理,完成图像的边缘检测。此外,当多组VLEP算子被同时使用时,考虑结合加权融合思想,以便获得更加丰富的边缘信息。实验结果表明,提出的边缘检测算法比其他经典的方法具有更好的边缘检测效果。展开更多
文摘讨论了数字化X射线成像系统调制传递函数(MTF)的刀口测量法.首先通过数值模拟方法研究了采样率和噪声对准确测量MTF的影响,真实测量中采用多条过采样刀口响应函数(ERF)取平均以压制噪声获取光滑的ERF曲线;然后用指数函数对所获ERF进行分段拟合以确保刀口边缘强度值变化的单调性,将由其获得的MTF值与线对卡结果进行比较,证明了该方法用于成像系统MTF测量的有效性.同时,通过实验分析介绍了刀口法材料、材料厚度、光源曝光电压及曝光时间的选择,最终在本系统测量中选择的刀口材料为1 mm厚铅板,曝光管电压为33 kV,曝光时间为10 s.
文摘A semi-length focal plane detecting system for heavy ions has been built onthe Beijing Q3D magnetic spectrometer and tested by <sup>12</sup>C+<sup>197</sup>Au,<sup>16</sup>O+<sup>150</sup>Sm,and <sup>18</sup>O-<sup>156</sup>Gd reactions.The intrinsic resolutions of position and angle were 1.1 mmand 0.8°,respectively.The resolutions of energy loss ΔE,residual energy E<sub>R</sub> and totalenergy E<sub>T</sub> obtained were 3.0%,1.4% and 0.9%.respectively,after a special method ofdata processing was adopted.The achievable mass resolution is estimated to be about1.0% after necessary corrections for some signals concerned.Discussion aboul the edgeeffect of the detectors of this type is given too.
文摘由于传统基于梯度的方形边缘检测算子包含边缘方向过少(一般为2个或4个方向),因此无法从多分辨率角度检测边缘,进而会丢失其他方向的边缘信息。针对上述问题,提出一种具有多尺度、多分辨率特性的边缘检测算子,称为可变局部边缘模式(Varied Local Edge Pattern,VLEP)算子,并用来提取图像边缘信息。算法主要思路包括,将图像经过高斯滤波器平滑,使用一组或多组VLEP算子与滤波后的图像进行卷积,得到边缘强度,从而获得边缘梯度值,最后设置适当的梯度阈值,对梯度图像进行二值化处理,完成图像的边缘检测。此外,当多组VLEP算子被同时使用时,考虑结合加权融合思想,以便获得更加丰富的边缘信息。实验结果表明,提出的边缘检测算法比其他经典的方法具有更好的边缘检测效果。
