Considering the decision-making variables of the capacities of branch roads and the optimization targets of lowering the saturation of arterial roads and the reconstruction expense of branch roads, the bi-level progra...Considering the decision-making variables of the capacities of branch roads and the optimization targets of lowering the saturation of arterial roads and the reconstruction expense of branch roads, the bi-level programming model for reconstructing the branch roads was set up. The upper level model was for determining the enlarged capacities of the branch roads, and the lower level model was for calculating the flows of road sections via the user equilibrium traffic assignment method. The genetic algorithm for solving the bi-level model was designed to obtain the reconstruction capacities of the branch roads. The results show that by the bi-level model and its algorithm, the optimum scheme of urban branch roads reconstruction can be gained, which reduces the saturation of arterial roads apparently, and alleviates traffic congestion. In the data analysis the arterial saturation decreases from 1.100 to 0.996, which verifies the micro-circulation transportation's function of urban branch road network.展开更多
Treatment of cranium and maxilla defects using CAD/ CA M techniques has been under the way. This makes it possible to rehabilitate the defective skull, to protect the intracranial structure from damage and to give t h...Treatment of cranium and maxilla defects using CAD/ CA M techniques has been under the way. This makes it possible to rehabilitate the defective skull, to protect the intracranial structure from damage and to give t he patient an individual implant with satisfying visual effect at same time. The general process of treatment are picking-up the shape information of defective skull from CT pictures of the patient, reconstructing 3-dimensional model of t he defect part, transforming the image data into manufacture data, and manufactu ring stage by means of choosing manufacture methods and certain material. As the prophase work a set of techniques was illustrated in the paper. The way of transforming helical CT data into an individual implant was introduced generally . Meanwhile, a prospective study of computer aided design and manufacture of tit anium skull for cranioplasty was reported. On these basic efforts, several resea rches and developments of relative techniques were described in detail inclu ding data conversion, 3-dimensional modeling and acquisition of the defect part geometric model. Data conversion focused on three points. The first one is about transforming the original CT information into digital data. The second one is about converting t he bitmap format data into vectorgraph format that is available for geometric mo deling in CAD system. And the third one is about finding a datum of all sect ion information in order to put the single slices together. The reconstructing o f 3-demetional entire skull model is achieved with two kinds of model. The 3D w ire model, which consists of a set of wires, is accomplished by translating the 2D plane information into 3D data in CAD system. This wire model is constructed ulteriorly to a surface model. During the efforts of gaining the surfaces geomet ry of the defect part, different means is used depending on where the defect loc ation is. Once the numerical based 3-dimensional model of the skull defect is e stablished the fixation design becomes a critical factors during the surgery, wh ich decides the vision effect and plays an important role in the success of the operation. For a finer prognosis a fixation interface, which is generated by the borders of the defect part and the surface contours considering the non-affect ed neighboring contours, is arranged.展开更多
矿山深部采空区已成为威胁矿山人员和生产设备安全的重要危险源。针对现有深部采空区探测方法成本高、时效性差、测量盲区多等问题,设计了一种探入式三维激光雷达扫描系统进行采空区探测。该系统采用廉价的机械旋转式激光雷达降低成本;...矿山深部采空区已成为威胁矿山人员和生产设备安全的重要危险源。针对现有深部采空区探测方法成本高、时效性差、测量盲区多等问题,设计了一种探入式三维激光雷达扫描系统进行采空区探测。该系统采用廉价的机械旋转式激光雷达降低成本;通过自主设计的基于图优化Cartographer-SLAM(Cartographer Simultaneous Localization and Mapping)算法,能够快速处理激光雷达数据,实现在井下实时定位与建图,提高了时效性;搭配探入式三维激光雷达扫描系统支架,可在危险巷道、采空区等人员难以进入的区域进行测量,有效减少测量盲区。为解决现有建模算法构建的采空区模型不光滑、孔洞多等问题,提出了一种基于移动最小二乘法(Moving Least Squares,MLS)优化的泊松曲面重建算法,对采空区点云数据进行建模,通过MLS法对数据点周围进行高阶多项式插值,经过八叉树分割、向量场计算、泊松方程求解、等值面提取,构建采空区三维模型。在辽宁省某金矿开展试验,通过采集多处采空区、巷道及地下硐室数据,实现了井下空间精确建模。试验结果表明:所设计的系统和算法,可高效、精确地实现深部复杂采空区三维建模,在一定程度上解决了深部复杂采空区探测中空区难以进入、存在测量盲区、建模精度不高等问题,为采空区管理和安全生产提供重要技术支持。展开更多
基于明暗恢复形状(shape from shading,简称SFS)方法进行海底侧扫声呐图像三维重建时,会因为方法中反射模型与海底表面不相符而降低重建精度。为此文章在分析大陆架海底表面特点及侧扫声呐工作机理的基础上,提出了基于SFS混合反射模型...基于明暗恢复形状(shape from shading,简称SFS)方法进行海底侧扫声呐图像三维重建时,会因为方法中反射模型与海底表面不相符而降低重建精度。为此文章在分析大陆架海底表面特点及侧扫声呐工作机理的基础上,提出了基于SFS混合反射模型的侧扫声呐图像海底地形重建方法。首先在保留Lambert漫反射模型的基础上引入Blinn-Phong镜面反射模型,并基于侧扫声呐图像粗糙度进行漫反射系数、镜面反射系数和镜面反射指数的自适应设计,从而形成适合复杂海底表面的混合反射模型;然后线性化处理辐射照度方程,并采用牛顿-拉夫逊方法来获得海底表面高程;最后根据海底点设计反演高程约束系数来约束表面高程,进而完成侧扫声呐图像的三维重建。试验测试结果表明,相较于其他三维重建方法,文中方法的平均绝对误差值VMAE平均降低了32.18%、相关系数值VCC平均提高了29.62%、信噪比值VSNR平均提升了27.23%,有效实现了侧扫声呐图像三维重建。展开更多
基金Project(2006CB705507) supported by the National Basic Research and Development Program of ChinaProject(20060533036) supported by the Specialized Research Foundation for the Doctoral Program of Higher Education of China
文摘Considering the decision-making variables of the capacities of branch roads and the optimization targets of lowering the saturation of arterial roads and the reconstruction expense of branch roads, the bi-level programming model for reconstructing the branch roads was set up. The upper level model was for determining the enlarged capacities of the branch roads, and the lower level model was for calculating the flows of road sections via the user equilibrium traffic assignment method. The genetic algorithm for solving the bi-level model was designed to obtain the reconstruction capacities of the branch roads. The results show that by the bi-level model and its algorithm, the optimum scheme of urban branch roads reconstruction can be gained, which reduces the saturation of arterial roads apparently, and alleviates traffic congestion. In the data analysis the arterial saturation decreases from 1.100 to 0.996, which verifies the micro-circulation transportation's function of urban branch road network.
文摘Treatment of cranium and maxilla defects using CAD/ CA M techniques has been under the way. This makes it possible to rehabilitate the defective skull, to protect the intracranial structure from damage and to give t he patient an individual implant with satisfying visual effect at same time. The general process of treatment are picking-up the shape information of defective skull from CT pictures of the patient, reconstructing 3-dimensional model of t he defect part, transforming the image data into manufacture data, and manufactu ring stage by means of choosing manufacture methods and certain material. As the prophase work a set of techniques was illustrated in the paper. The way of transforming helical CT data into an individual implant was introduced generally . Meanwhile, a prospective study of computer aided design and manufacture of tit anium skull for cranioplasty was reported. On these basic efforts, several resea rches and developments of relative techniques were described in detail inclu ding data conversion, 3-dimensional modeling and acquisition of the defect part geometric model. Data conversion focused on three points. The first one is about transforming the original CT information into digital data. The second one is about converting t he bitmap format data into vectorgraph format that is available for geometric mo deling in CAD system. And the third one is about finding a datum of all sect ion information in order to put the single slices together. The reconstructing o f 3-demetional entire skull model is achieved with two kinds of model. The 3D w ire model, which consists of a set of wires, is accomplished by translating the 2D plane information into 3D data in CAD system. This wire model is constructed ulteriorly to a surface model. During the efforts of gaining the surfaces geomet ry of the defect part, different means is used depending on where the defect loc ation is. Once the numerical based 3-dimensional model of the skull defect is e stablished the fixation design becomes a critical factors during the surgery, wh ich decides the vision effect and plays an important role in the success of the operation. For a finer prognosis a fixation interface, which is generated by the borders of the defect part and the surface contours considering the non-affect ed neighboring contours, is arranged.
文摘矿山深部采空区已成为威胁矿山人员和生产设备安全的重要危险源。针对现有深部采空区探测方法成本高、时效性差、测量盲区多等问题,设计了一种探入式三维激光雷达扫描系统进行采空区探测。该系统采用廉价的机械旋转式激光雷达降低成本;通过自主设计的基于图优化Cartographer-SLAM(Cartographer Simultaneous Localization and Mapping)算法,能够快速处理激光雷达数据,实现在井下实时定位与建图,提高了时效性;搭配探入式三维激光雷达扫描系统支架,可在危险巷道、采空区等人员难以进入的区域进行测量,有效减少测量盲区。为解决现有建模算法构建的采空区模型不光滑、孔洞多等问题,提出了一种基于移动最小二乘法(Moving Least Squares,MLS)优化的泊松曲面重建算法,对采空区点云数据进行建模,通过MLS法对数据点周围进行高阶多项式插值,经过八叉树分割、向量场计算、泊松方程求解、等值面提取,构建采空区三维模型。在辽宁省某金矿开展试验,通过采集多处采空区、巷道及地下硐室数据,实现了井下空间精确建模。试验结果表明:所设计的系统和算法,可高效、精确地实现深部复杂采空区三维建模,在一定程度上解决了深部复杂采空区探测中空区难以进入、存在测量盲区、建模精度不高等问题,为采空区管理和安全生产提供重要技术支持。
文摘基于明暗恢复形状(shape from shading,简称SFS)方法进行海底侧扫声呐图像三维重建时,会因为方法中反射模型与海底表面不相符而降低重建精度。为此文章在分析大陆架海底表面特点及侧扫声呐工作机理的基础上,提出了基于SFS混合反射模型的侧扫声呐图像海底地形重建方法。首先在保留Lambert漫反射模型的基础上引入Blinn-Phong镜面反射模型,并基于侧扫声呐图像粗糙度进行漫反射系数、镜面反射系数和镜面反射指数的自适应设计,从而形成适合复杂海底表面的混合反射模型;然后线性化处理辐射照度方程,并采用牛顿-拉夫逊方法来获得海底表面高程;最后根据海底点设计反演高程约束系数来约束表面高程,进而完成侧扫声呐图像的三维重建。试验测试结果表明,相较于其他三维重建方法,文中方法的平均绝对误差值VMAE平均降低了32.18%、相关系数值VCC平均提高了29.62%、信噪比值VSNR平均提升了27.23%,有效实现了侧扫声呐图像三维重建。
