This paper introduces some latest developments regarding the X-ray imaging methodology and applications of the X-ray imaging and biomedical application beamline(BL13W1)at Shanghai Synchrotron Radiation Facility in the...This paper introduces some latest developments regarding the X-ray imaging methodology and applications of the X-ray imaging and biomedical application beamline(BL13W1)at Shanghai Synchrotron Radiation Facility in the past 5 years.The photon energy range of the beamline is 8–72.5 keV.Several sets of X-ray imaging detectors with different pixel sizes(0.19–24 lm)are used to realize X-ray microcomputed tomography(X-ray micro-CT)and X-ray in-line phase-contrast imaging.To satisfy the requirements of user experiments,new X-ray imaging methods and image processing techniques are developed.In vivo dynamic micro-CT experiments with living insects are performed in 0.5 s(sampling rate of 2 Hz,2 tomograms/s)with a monochromatic beam from a wiggler source and in 40 ms(sampling rate of 25 Hz,25 tomograms/s)with a white beam from a bending magnet source.A new X-ray imaging method known as move contrast X-ray imaging is proposed,with which blood flow and moving tissues in raw images can be distinguished according to their moving frequencies in the time domain.Furthermore,X-ray speckle-tracking imaging with twice exposures to eliminate the edge enhancement effect is developed.A high-precision quantification method is realized to measure complex three-dimensional blood vessels obtained via X-ray micro-CT.X-ray imaging methods such as three-dimensional X-ray diffraction microscopy,small-angle X-ray scattering CT,and X-ray fluorescence CT are developed,in which the X-ray micro-CT imaging method is combined with other contrast mechanisms such as diffraction,scattering,and fluorescence contrasts respectively.Moreover,an X-ray nano-CT experiment is performed with a 100 nm spatial resolution.Typical user experimental results from the fields of material science,biomedicine,paleontology,physics,chemistry,and environmental science obtained on the beamline are provided.展开更多
Cooperative target identification is the prerequisite for the relative position and orientation measurement between the space robot arm and the to-be-arrested object. We propose an on- orbit real-time robust algorithm...Cooperative target identification is the prerequisite for the relative position and orientation measurement between the space robot arm and the to-be-arrested object. We propose an on- orbit real-time robust algorithm for cooperative target identification in complex background using the features of circle and lines. It first extracts only the interested edges in the target image using an adaptive threshold and refines them to about single-pixel-width with improved non-maximum suppression. Adapting a novel tracking approach, edge segments changing smoothly in tangential directions are obtained. With a small amount of calculation, large numbers of invalid edges are removed. From the few remained edges, valid circular arcs are extracted and reassembled to obtain circles according to a reliable criterion. Finally, the target is identified if there are certain numbers of straight lines whose relative positions with the circle match the known target pattern. Experiments demonstrate that the proposed algorithm accurately identifies the cooperative target within the range of 0.3 1.5 m under complex background at the speed of 8 frames per second, regardless of lighting condition and target attitude. The proposed algorithm is very suitable for real-time visual measurement of space robot arm because of its robustness and small memory requirement.展开更多
基金This work was supported by the National Key Research and Development Program of China(Nos.2017YFA0403801,2016YFA0401302,2017YFA0206004,2018YFC1200204)the National Major Scientific Instruments and Equipment Development Project of China(No.11627901).
文摘This paper introduces some latest developments regarding the X-ray imaging methodology and applications of the X-ray imaging and biomedical application beamline(BL13W1)at Shanghai Synchrotron Radiation Facility in the past 5 years.The photon energy range of the beamline is 8–72.5 keV.Several sets of X-ray imaging detectors with different pixel sizes(0.19–24 lm)are used to realize X-ray microcomputed tomography(X-ray micro-CT)and X-ray in-line phase-contrast imaging.To satisfy the requirements of user experiments,new X-ray imaging methods and image processing techniques are developed.In vivo dynamic micro-CT experiments with living insects are performed in 0.5 s(sampling rate of 2 Hz,2 tomograms/s)with a monochromatic beam from a wiggler source and in 40 ms(sampling rate of 25 Hz,25 tomograms/s)with a white beam from a bending magnet source.A new X-ray imaging method known as move contrast X-ray imaging is proposed,with which blood flow and moving tissues in raw images can be distinguished according to their moving frequencies in the time domain.Furthermore,X-ray speckle-tracking imaging with twice exposures to eliminate the edge enhancement effect is developed.A high-precision quantification method is realized to measure complex three-dimensional blood vessels obtained via X-ray micro-CT.X-ray imaging methods such as three-dimensional X-ray diffraction microscopy,small-angle X-ray scattering CT,and X-ray fluorescence CT are developed,in which the X-ray micro-CT imaging method is combined with other contrast mechanisms such as diffraction,scattering,and fluorescence contrasts respectively.Moreover,an X-ray nano-CT experiment is performed with a 100 nm spatial resolution.Typical user experimental results from the fields of material science,biomedicine,paleontology,physics,chemistry,and environmental science obtained on the beamline are provided.
基金supported by the National Basic Research Program of China (No. 2013CB733103)
文摘Cooperative target identification is the prerequisite for the relative position and orientation measurement between the space robot arm and the to-be-arrested object. We propose an on- orbit real-time robust algorithm for cooperative target identification in complex background using the features of circle and lines. It first extracts only the interested edges in the target image using an adaptive threshold and refines them to about single-pixel-width with improved non-maximum suppression. Adapting a novel tracking approach, edge segments changing smoothly in tangential directions are obtained. With a small amount of calculation, large numbers of invalid edges are removed. From the few remained edges, valid circular arcs are extracted and reassembled to obtain circles according to a reliable criterion. Finally, the target is identified if there are certain numbers of straight lines whose relative positions with the circle match the known target pattern. Experiments demonstrate that the proposed algorithm accurately identifies the cooperative target within the range of 0.3 1.5 m under complex background at the speed of 8 frames per second, regardless of lighting condition and target attitude. The proposed algorithm is very suitable for real-time visual measurement of space robot arm because of its robustness and small memory requirement.
