在继承平方公里阵列(Square Kilometre Array,SKA)望远镜的中国低频探路者——"宇宙第一缕曙光"探测项目21CMA在十年间所积累的经验和广泛国际合作的基础上,计划小规模改造现有设备,迅速掌握数字多波束合成、高动态大视场成...在继承平方公里阵列(Square Kilometre Array,SKA)望远镜的中国低频探路者——"宇宙第一缕曙光"探测项目21CMA在十年间所积累的经验和广泛国际合作的基础上,计划小规模改造现有设备,迅速掌握数字多波束合成、高动态大视场成像、前景去除等SKA低频成像的关键核心技术。同时,与SKA低频阵(SKA-low)先导设备MWA(Murchison Widefield Array)开展深层次合作,预选未来用于SKA1-low宇宙再电离深度成像的观测候选区域,为最终利用SKA第一阶段(SKA1)低频阵列,对选定观测候选区域进行深度定点观测做好充分准备,最终实现SKA1既定的首要科学目标。该项目还将建设中国SKA区域中心数据处理原型样机,并以21CMA和MWA实测数据为基础,完成低频射电干涉成像的数据处理流程,为建设中国SKA区域数据中心打下基础。展开更多
Dynamic envelope curve is a significant parameter to assess the running safety of high-speed trains.Up to now the method based on binocular stereo vision is the only way available to measure the dynamic envelope curve...Dynamic envelope curve is a significant parameter to assess the running safety of high-speed trains.Up to now the method based on binocular stereo vision is the only way available to measure the dynamic envelope curve of a train,the speed of which is over200km/h.Nevertheless the method has two limitations,one is large field-〇f-view(FO V),the other is calibration time.Hence portable calibration equipment,easy-t〇-build target and rapid calibration algorithm are required to complete the calibration.In this paper,a new rapid on-site calibration method with large FOV based on binocular stereo vision is proposed.To address these issues,a light target has been designed,the rail coordinate system(RCS)is represented by40fixed retroreflective points on the target,and they are utilized to calibrate the parameters of two cameras.In addition,two cameras merely capture a single image of the target simultaneously,and the intrinsic and extrinsic parameters of the cameras can be calculated rapidly.To testify the proposed method,the experiments have been conducted and the results reveal that the accuracy can reach+1mm,which can meet the measurement requirement.展开更多
Background modeling and subtraction is a fundamental problem in video analysis. Many algorithms have been developed to date, but there are still some challenges in complex environments, especially dynamic scenes in wh...Background modeling and subtraction is a fundamental problem in video analysis. Many algorithms have been developed to date, but there are still some challenges in complex environments, especially dynamic scenes in which backgrounds are themselves moving, such as rippling water and swaying trees. In this paper, a novel background modeling method is proposed for dynamic scenes by combining both tensor representation and swarm intelligence. We maintain several video patches, which are naturally represented as higher order tensors,to represent the patterns of background, and utilize tensor low-rank approximation to capture the dynamic nature. Furthermore, we introduce an ant colony algorithm to improve the performance. Experimental results show that the proposed method is robust and adaptive in dynamic environments, and moving objects can be perfectly separated from the complex dynamic background.展开更多
文摘在继承平方公里阵列(Square Kilometre Array,SKA)望远镜的中国低频探路者——"宇宙第一缕曙光"探测项目21CMA在十年间所积累的经验和广泛国际合作的基础上,计划小规模改造现有设备,迅速掌握数字多波束合成、高动态大视场成像、前景去除等SKA低频成像的关键核心技术。同时,与SKA低频阵(SKA-low)先导设备MWA(Murchison Widefield Array)开展深层次合作,预选未来用于SKA1-low宇宙再电离深度成像的观测候选区域,为最终利用SKA第一阶段(SKA1)低频阵列,对选定观测候选区域进行深度定点观测做好充分准备,最终实现SKA1既定的首要科学目标。该项目还将建设中国SKA区域中心数据处理原型样机,并以21CMA和MWA实测数据为基础,完成低频射电干涉成像的数据处理流程,为建设中国SKA区域数据中心打下基础。
基金National Science and Technology Major Project of China(No.2016ZX04003001)
文摘Dynamic envelope curve is a significant parameter to assess the running safety of high-speed trains.Up to now the method based on binocular stereo vision is the only way available to measure the dynamic envelope curve of a train,the speed of which is over200km/h.Nevertheless the method has two limitations,one is large field-〇f-view(FO V),the other is calibration time.Hence portable calibration equipment,easy-t〇-build target and rapid calibration algorithm are required to complete the calibration.In this paper,a new rapid on-site calibration method with large FOV based on binocular stereo vision is proposed.To address these issues,a light target has been designed,the rail coordinate system(RCS)is represented by40fixed retroreflective points on the target,and they are utilized to calibrate the parameters of two cameras.In addition,two cameras merely capture a single image of the target simultaneously,and the intrinsic and extrinsic parameters of the cameras can be calculated rapidly.To testify the proposed method,the experiments have been conducted and the results reveal that the accuracy can reach+1mm,which can meet the measurement requirement.
基金supported by National Natural Science Foundation of China (Grant Nos. 11301137 and 11371036)the National Science Foundation of Hebei Province of China (Grant No. A2014205100
文摘Background modeling and subtraction is a fundamental problem in video analysis. Many algorithms have been developed to date, but there are still some challenges in complex environments, especially dynamic scenes in which backgrounds are themselves moving, such as rippling water and swaying trees. In this paper, a novel background modeling method is proposed for dynamic scenes by combining both tensor representation and swarm intelligence. We maintain several video patches, which are naturally represented as higher order tensors,to represent the patterns of background, and utilize tensor low-rank approximation to capture the dynamic nature. Furthermore, we introduce an ant colony algorithm to improve the performance. Experimental results show that the proposed method is robust and adaptive in dynamic environments, and moving objects can be perfectly separated from the complex dynamic background.
