A spatially adaptive (SA) two-dimensional (2-D) numerical wave flume is presented based on the quadtree mesh system,in which a new multiple particle level set (MPLS) method is proposed to solve the problem of interfac...A spatially adaptive (SA) two-dimensional (2-D) numerical wave flume is presented based on the quadtree mesh system,in which a new multiple particle level set (MPLS) method is proposed to solve the problem of interface tracking,in which common intersection may be traversed by multiple interfaces.By using the adaptive mesh technique and the MPLS method,mesh resolution is updated automatically with time according to flow characteristics in the modeling process with higher resolution around the free surface and the solid boundary and lower resolution in less important area.The model has good performance in saving computer memory and CPU time and is validated by computational examples of small amplitude wave,second-order Stokes wave and cnoidal wave.Computational results also indicate that standing wave and wave overtopping are also reasonably simulated by the model.展开更多
遥感图像经常被条带噪声污染,导致图像质量下降。为了去除条带噪声,本文提出了一种基于空间自适应变分的噪声抑制方法。首先,对条带噪声建模,并利用信噪比较高的区域估计出模型的增益和偏置;然后,在变分法的框架下,构建能量函数,并引入...遥感图像经常被条带噪声污染,导致图像质量下降。为了去除条带噪声,本文提出了一种基于空间自适应变分的噪声抑制方法。首先,对条带噪声建模,并利用信噪比较高的区域估计出模型的增益和偏置;然后,在变分法的框架下,构建能量函数,并引入空间自适应正则因子,根据图像空间信息自适应调整正则参数;最后,采用分裂式Bregman算法优化能量函数,得到去噪图像的最优解。实验表明,本文算法可以将实际遥感图像等效视数由37.26提高到76.48,辐射质量提升因子提高到8.52 d B。本文算法能够有效去除条带噪声,保留图像细节,改善图像质量。展开更多
基金The Innovative Research Groups of the National Natural Science Foundation of China under contract No.51021004the National Natural Science Foundation for Youth of China under contract No. 51109018+2 种基金the Open Foundation of Water & Sediment Science and Water Hazard Prevention Hunan Provincial Key Laboratory under contract No. 2011SS05the Open Foundation of Port,Coastal and offshore Engineering Hunan Provincial Key Discipline under contract No. 20110815001the Open Foundation of State Key Laboratory of Hydraulic Engineering Simulation and Safety under contract No.HSSKLTJU-201208.
文摘A spatially adaptive (SA) two-dimensional (2-D) numerical wave flume is presented based on the quadtree mesh system,in which a new multiple particle level set (MPLS) method is proposed to solve the problem of interface tracking,in which common intersection may be traversed by multiple interfaces.By using the adaptive mesh technique and the MPLS method,mesh resolution is updated automatically with time according to flow characteristics in the modeling process with higher resolution around the free surface and the solid boundary and lower resolution in less important area.The model has good performance in saving computer memory and CPU time and is validated by computational examples of small amplitude wave,second-order Stokes wave and cnoidal wave.Computational results also indicate that standing wave and wave overtopping are also reasonably simulated by the model.
文摘遥感图像经常被条带噪声污染,导致图像质量下降。为了去除条带噪声,本文提出了一种基于空间自适应变分的噪声抑制方法。首先,对条带噪声建模,并利用信噪比较高的区域估计出模型的增益和偏置;然后,在变分法的框架下,构建能量函数,并引入空间自适应正则因子,根据图像空间信息自适应调整正则参数;最后,采用分裂式Bregman算法优化能量函数,得到去噪图像的最优解。实验表明,本文算法可以将实际遥感图像等效视数由37.26提高到76.48,辐射质量提升因子提高到8.52 d B。本文算法能够有效去除条带噪声,保留图像细节,改善图像质量。
