目的探讨使用时间-空间标记反转脉冲(time-spatial labeling inversion p u l s e,Ti m e-S L I P)非对比增强血管成像技术评价肾动脉的价值。材料与方法使用1.5 T MR扫描仪对36例临床怀疑肾动脉狭窄的患者行Time-SLIP磁共振血管造影术(...目的探讨使用时间-空间标记反转脉冲(time-spatial labeling inversion p u l s e,Ti m e-S L I P)非对比增强血管成像技术评价肾动脉的价值。材料与方法使用1.5 T MR扫描仪对36例临床怀疑肾动脉狭窄的患者行Time-SLIP磁共振血管造影术(magnetic resonance angiography,MRA)检查。以320排CT血管造影(computed tomography angiography,CTA)和数字减影血管造影(digital subtraction angiography,DSA)为参考标准,评价Time-SLIP肾动脉MRA的图像质量和诊断肾动脉狭窄的能力。结果共71支肾动脉纳入研究,图像质量优秀的有51支(72%),良好的有17支(24%),差的有3支(4%)。Time-SLIP MRA诊断肾动脉狭窄的敏感度、特异度分别为100%、98.2%,诊断明显狭窄(狭窄程度>50%)的敏感度、特异度分别为90%、98.4%。Time-SLIP MRA定量评估肾动脉狭窄程度与CTA和DSA呈高度相关(r=0.959,P<0.01),但Time-SLIP MRA轻度高估肾动脉的狭窄程度[平均偏倚为(3.31±10.04)%]。结论 Time-SLIP非对比增强血管成像技术能够准确评价肾动脉。展开更多
To decrease number of samples for the implementation of color space transformation, a method for modeling the chromatic characterization of video cameras was proposed. An additional transformation was required to pred...To decrease number of samples for the implementation of color space transformation, a method for modeling the chromatic characterization of video cameras was proposed. An additional transformation was required to predict output RGB values for an input color. This additional transformation was based on spectral reflectance relationship. The transformed color coordinates were taken as inputs of a multilayer neural network. Based on network outputs, the RGB values to be predicted were calculated. Experimental results were given to illustrate the performance of the method. Even though much less number of training samples are used, this method can also perform well on this color space transformation.展开更多
To transfer the color data from a device (video camera) dependent color space into a device? independent color space, a multilayer feedforward network with the error backpropagation (BP) learning rule, was regarded ...To transfer the color data from a device (video camera) dependent color space into a device? independent color space, a multilayer feedforward network with the error backpropagation (BP) learning rule, was regarded as a nonlinear transformer realizing the mapping from the RGB color space to CIELAB color space. A variety of mapping accuracy were obtained with different network structures. BP neural networks can provide a satisfactory mapping accuracy in the field of color space transformation for video cameras.展开更多
Based upon ArCGIS,the vertical spatial transfer law of cultivated land in Yunnan was studied through referring to three periods of remote sensing data of Land-Use and Land-Cover Change（LUCC） in Yunnan in 1986,1995 a...Based upon ArCGIS,the vertical spatial transfer law of cultivated land in Yunnan was studied through referring to three periods of remote sensing data of Land-Use and Land-Cover Change（LUCC） in Yunnan in 1986,1995 and 2000,Digital Elevation Model（DEM） of Yunnan Province and LUCC data in Yunnan from 2000 to 2008.The main factors that promote vertical spatial transfer law of cultivated land were analyzed by using SPSS,and the influence of policies and government acts upon the change of cultivated land was clarified.The findings indicated that for Yunnan cultivated land there is a trend that in the vertical direction steep slope areas and gentle slope areas divert into mid-slope areas.The primary factor influencing the vertical spatial transfer of cultivated land was policies and government acts.Also,the gradient of ground,total population and number of agriculture employed persons were also main factors in influencing the change of cultivated land,whose influence was obviously below policies and government acts.展开更多
文摘目的探讨使用时间-空间标记反转脉冲(time-spatial labeling inversion p u l s e,Ti m e-S L I P)非对比增强血管成像技术评价肾动脉的价值。材料与方法使用1.5 T MR扫描仪对36例临床怀疑肾动脉狭窄的患者行Time-SLIP磁共振血管造影术(magnetic resonance angiography,MRA)检查。以320排CT血管造影(computed tomography angiography,CTA)和数字减影血管造影(digital subtraction angiography,DSA)为参考标准,评价Time-SLIP肾动脉MRA的图像质量和诊断肾动脉狭窄的能力。结果共71支肾动脉纳入研究,图像质量优秀的有51支(72%),良好的有17支(24%),差的有3支(4%)。Time-SLIP MRA诊断肾动脉狭窄的敏感度、特异度分别为100%、98.2%,诊断明显狭窄(狭窄程度>50%)的敏感度、特异度分别为90%、98.4%。Time-SLIP MRA定量评估肾动脉狭窄程度与CTA和DSA呈高度相关(r=0.959,P<0.01),但Time-SLIP MRA轻度高估肾动脉的狭窄程度[平均偏倚为(3.31±10.04)%]。结论 Time-SLIP非对比增强血管成像技术能够准确评价肾动脉。
文摘To decrease number of samples for the implementation of color space transformation, a method for modeling the chromatic characterization of video cameras was proposed. An additional transformation was required to predict output RGB values for an input color. This additional transformation was based on spectral reflectance relationship. The transformed color coordinates were taken as inputs of a multilayer neural network. Based on network outputs, the RGB values to be predicted were calculated. Experimental results were given to illustrate the performance of the method. Even though much less number of training samples are used, this method can also perform well on this color space transformation.
文摘To transfer the color data from a device (video camera) dependent color space into a device? independent color space, a multilayer feedforward network with the error backpropagation (BP) learning rule, was regarded as a nonlinear transformer realizing the mapping from the RGB color space to CIELAB color space. A variety of mapping accuracy were obtained with different network structures. BP neural networks can provide a satisfactory mapping accuracy in the field of color space transformation for video cameras.
基金Supported by National Natural and Scientific Foundation Project(40761009)Yunnan Province Applied Fundamental Research Project(2007D081M)Assisted by the Project of Yunnan Province Department of Education(06Y045A)~~
文摘Based upon ArCGIS,the vertical spatial transfer law of cultivated land in Yunnan was studied through referring to three periods of remote sensing data of Land-Use and Land-Cover Change（LUCC） in Yunnan in 1986,1995 and 2000,Digital Elevation Model（DEM） of Yunnan Province and LUCC data in Yunnan from 2000 to 2008.The main factors that promote vertical spatial transfer law of cultivated land were analyzed by using SPSS,and the influence of policies and government acts upon the change of cultivated land was clarified.The findings indicated that for Yunnan cultivated land there is a trend that in the vertical direction steep slope areas and gentle slope areas divert into mid-slope areas.The primary factor influencing the vertical spatial transfer of cultivated land was policies and government acts.Also,the gradient of ground,total population and number of agriculture employed persons were also main factors in influencing the change of cultivated land,whose influence was obviously below policies and government acts.
