Elbow draft-tubes are widely used in large- and medium-sized hydropower stations in many countries. During the application, handling the somatotype of elbow tubes has been found challenging: in order to maintain the ...Elbow draft-tubes are widely used in large- and medium-sized hydropower stations in many countries. During the application, handling the somatotype of elbow tubes has been found challenging: in order to maintain the designed shape of draft tube and to meet the requirement of construction lofting, the configuration of reinforcing bars and the fabrication of templates, the geometry of elbow tubes has to be accurately calculated to draw engineering graphics. Based on the derived equations in this paper, the motion of elbow tube curve envelope is simulated by using computers, which shows directly the smoothness of the curve and provides dynamic simulation for the study and optimization of the design and construction of elbow draft tubes, along with the front view and bottom view.展开更多
目的探讨妊娠及产褥期出血性脑卒中(hemorrhagic stroke during pregnancy and the puerperium,HSPP)的头部电子计算机体层扫描(CT)、磁共振成像(MRI)、三维计算机断层扫描血管造影(3D-CTA)、数字减影血管造影(DSA)表现的诊断价值。方法...目的探讨妊娠及产褥期出血性脑卒中(hemorrhagic stroke during pregnancy and the puerperium,HSPP)的头部电子计算机体层扫描(CT)、磁共振成像(MRI)、三维计算机断层扫描血管造影(3D-CTA)、数字减影血管造影(DSA)表现的诊断价值。方法 2004年6月至2007年7月中国医科大学附属盛京医院收治7例HSPP,回顾性分析其临床及影像学资料。7例患者发病后均行CT检查,行MRI检查1例,3D-CTA检查2例,DSA检查4例。结果 CT表现基底节或脑叶局部高密度影6例,双侧外侧裂少量高密度充填影1例。1例MRI表现T1WI等高混杂信号、T2WI低混杂信号;1例3D-CTA呈现左顶高密度不规则血管团,另1例3D-CTA正常。4例DSA证实3例脑血管动静脉畸形(arteriovenous malformation,AVM)、1例正常。3D-CTA检查结果与DSA相符。头部影像学检查提示蛛网膜下腔出血(subarachnoid hemorrhage,SAH)1例,基底节区脑出血2例,脑叶出血4例;病因为AVM破裂出血4例,依据DSA诊断3例,依据CT表现及既往病史诊断1例。结论头部CT及MRI是诊断HSPP的首选手段,3D-CTA及DSA有助于病因判断。展开更多
Based on the homography between a multi-source image and three-dimensional (3D) measurement points, this letter proposes a novel 3D registration and integration method based on scale-invariant feature matching. The ...Based on the homography between a multi-source image and three-dimensional (3D) measurement points, this letter proposes a novel 3D registration and integration method based on scale-invariant feature matching. The matching relationships of two-dimensional (2D) texture gray images and two-and-a-half- dimensional (2.5D) range images are constructed using the scale-invariant feature transform algorithms. Then, at least three non-collinear 3D measurement points corresponding to image feature points are used to achieve a registration relationship accurately. According to the index of overlapping images and the local 3D border search method, multi-view registration data are rapidly and accurately integrated. Exper- imental results on real models demonstrate that the algorithm is robust and effective.展开更多
基金Supported by Open Fund of Key Laboratory of Ministry of Education of Hydraulic and Waterway Engineering of Chongqing Jiaotong University Province and Department Construction together(SLK2009A04)
文摘Elbow draft-tubes are widely used in large- and medium-sized hydropower stations in many countries. During the application, handling the somatotype of elbow tubes has been found challenging: in order to maintain the designed shape of draft tube and to meet the requirement of construction lofting, the configuration of reinforcing bars and the fabrication of templates, the geometry of elbow tubes has to be accurately calculated to draw engineering graphics. Based on the derived equations in this paper, the motion of elbow tube curve envelope is simulated by using computers, which shows directly the smoothness of the curve and provides dynamic simulation for the study and optimization of the design and construction of elbow draft tubes, along with the front view and bottom view.
文摘目的探讨妊娠及产褥期出血性脑卒中(hemorrhagic stroke during pregnancy and the puerperium,HSPP)的头部电子计算机体层扫描(CT)、磁共振成像(MRI)、三维计算机断层扫描血管造影(3D-CTA)、数字减影血管造影(DSA)表现的诊断价值。方法 2004年6月至2007年7月中国医科大学附属盛京医院收治7例HSPP,回顾性分析其临床及影像学资料。7例患者发病后均行CT检查,行MRI检查1例,3D-CTA检查2例,DSA检查4例。结果 CT表现基底节或脑叶局部高密度影6例,双侧外侧裂少量高密度充填影1例。1例MRI表现T1WI等高混杂信号、T2WI低混杂信号;1例3D-CTA呈现左顶高密度不规则血管团,另1例3D-CTA正常。4例DSA证实3例脑血管动静脉畸形(arteriovenous malformation,AVM)、1例正常。3D-CTA检查结果与DSA相符。头部影像学检查提示蛛网膜下腔出血(subarachnoid hemorrhage,SAH)1例,基底节区脑出血2例,脑叶出血4例;病因为AVM破裂出血4例,依据DSA诊断3例,依据CT表现及既往病史诊断1例。结论头部CT及MRI是诊断HSPP的首选手段,3D-CTA及DSA有助于病因判断。
基金supported by the National "863" Program of China (No. 2009BAI81B02)the Doctoral Foundation of the Ministry of Education (No.20070287055)
文摘Based on the homography between a multi-source image and three-dimensional (3D) measurement points, this letter proposes a novel 3D registration and integration method based on scale-invariant feature matching. The matching relationships of two-dimensional (2D) texture gray images and two-and-a-half- dimensional (2.5D) range images are constructed using the scale-invariant feature transform algorithms. Then, at least three non-collinear 3D measurement points corresponding to image feature points are used to achieve a registration relationship accurately. According to the index of overlapping images and the local 3D border search method, multi-view registration data are rapidly and accurately integrated. Exper- imental results on real models demonstrate that the algorithm is robust and effective.