UE-Brzier （unified and extended Brzier） basis is the unified form of Brzier-like bases, including polynomial Brzier basis, trigonometric polynomial and hyperbolic polynomial Brzier basis. Similar to the original Brz...UE-Brzier （unified and extended Brzier） basis is the unified form of Brzier-like bases, including polynomial Brzier basis, trigonometric polynomial and hyperbolic polynomial Brzier basis. Similar to the original Brzier-like bases, UE-Brzier basis func-tions are not orthogonal. In this paper, a group of orthogonal basis is constructed based on UE-Brzier basis. The transformation matrices between UE-Brzier basis and the proposed orthogonal basis are also solved.展开更多
目的针对低质量浅浮雕表面的噪声现象,提出一种二次联合局部自适应稀疏表示和非局部低秩矩阵近似的浅浮雕优化算法。方法本文方法分两个阶段。第1阶段,将浅浮雕灰度图划分成大小相同的数据块,提取边界块并进行去噪,分别对数据块进行稀...目的针对低质量浅浮雕表面的噪声现象,提出一种二次联合局部自适应稀疏表示和非局部低秩矩阵近似的浅浮雕优化算法。方法本文方法分两个阶段。第1阶段,将浅浮雕灰度图划分成大小相同的数据块,提取边界块并进行去噪,分别对数据块进行稀疏表示和低秩近似处理。一方面,通过字典学习获得过完备字典和稀疏编码;另一方面,利用K均值聚类算法(K-means)将事先构建的外部字典库划分成k类,从k个簇中心匹配每个数据块的相似块并组成相似矩阵,依次进行低秩近似和特征增强处理。最后通过最小二乘法求解,重建并聚合新建数据块以得到新的高度场。第2阶段与第1阶段的结构相似,主要区别在于改用重建高度场的非局部自身相似性来实现块匹配。结果在不同图像压缩率下(70%,50%,30%),对比本文方法与BM3D(block-matching and 3D filtering)、WNNM(weighted nuclear norm minimization)、STROLLR(sparsifying transform learning and low-rank)、TWSC(trilateral weighted sparse coding)4个平滑降噪方法的浅浮雕重建结果,发现BM3D和STROLLR方法的特征保持虽好,但平滑效果较差,WNNM方法出现模型破损现象,TWSC方法的平滑效果比BM3D和STROLLR方法更好,但特征也同时被光顺化。阴影恢复形状法(shape from shading,SFS)是一种基于图像的3D建模法,但是其重建结果比较粗糙。相比之下,本文方法生成的浅浮雕模型更加清晰直观,在浅浮雕的特征增强和平滑去噪方面都展现出更好的性能。结论本文综合数据块的局部稀疏性和数据块之间的非局部相似性对粗糙的浅浮雕模型进行二次高度场重建。本文方法有效改善了现有浅浮雕模型的质量,提高了模型的整体视觉效果,为浅浮雕的优化提供了新方法。展开更多
With daily reanalysis data by NCEP/NCAR and data of tropical cyclones landing over China from 1949 to 2005, the variation of low-frequency oscillations of equatorial pressure and their relationship with tropical cyclo...With daily reanalysis data by NCEP/NCAR and data of tropical cyclones landing over China from 1949 to 2005, the variation of low-frequency oscillations of equatorial pressure and their relationship with tropical cyclones landing over China in the summer half of the years (June through October) are studied for the 57 years, using spectral analysis and correlation analysis. The results show that the summertime equatorial pressure is mainly of periodic oscillations of 5―7 days and 10―30 days and the interannual variation of the intensity of its quasi-biweekly oscillation is significantly positive correlation with the number of tropical cyclones landing over China. The quasi-biweekly oscillation is filtered from daily equatorial pressure in May―November over the 57 years with inverse wavelet transform and the probability for tropical cyclones landing on coastal China within four days before and after the oscillatory valleys of quasi-biweekly pressure at the equator is 59.7% and 73.0% for June to October and July to September respectively. The model of atmospheric circulation for quasi-biweekly oscillatory valleys of equatorial pressure in association with or without tropical cyclones landing over China in July―September is set up with the composite analysis method. When the valleys are associated with (without) landfall, zonal (meridional) circulation prevails in the mid and high latitudes of the Eastern Hemisphere, the high pressure ridge is weak (strong) near the Sea of Okhotsk, the westerly zone is northward (southward), the subtropical high is westward (eastward) in location and strong (weak) in intensity, the cross-equatorial flow is strong (weak) in southeast Asia, Southwest Monsoon is strong (weak) and stronger (weaker) while in the valleys of pressure, being favorable (unfavorable) for tropical cyclones landing over China. The atmospheric circulation model for oscillatory valleys of biweekly equatorial pressure in association with (without) tropical cyclones landing over China, which can reflect the difference of atmospheric circulation between them, is beneficial to medium-term forecasts of tropical cyclones landing over China.展开更多
The interdecadal variation of coral grayness in northern South China Sea (SCS) is studied using the annual mean coral grayness in northern SCS from 1789 to 1992 and annual precipitation at Guangzhou from 1908 to 1992 ...The interdecadal variation of coral grayness in northern South China Sea (SCS) is studied using the annual mean coral grayness in northern SCS from 1789 to 1992 and annual precipitation at Guangzhou from 1908 to 1992 by Singular Spectrum Analysis (SSA), correlation analysis, Mann-Kendall’s abrupt change analysis and composite analysis. The interdecadal variation of south China precipitation as reflected by the series of Guangzhou precipitation rebuilt with the coral grayness is discussed. The results show that the variation of coral grayness in SCS has significant terms of tendency, much-weighted interdecadal variation and weak interannual variation. There was a century-scale abrupt change of coral grayness at the end of the 1880s that changed from positive anomalies to negative anomalies. The global field of SST difference corresponding to the point of abrupt change was negative anomalies over the SCS and neighboring northern Indian Ocean, most of central and western Pacific Ocean and coastal areas of the northern Atlantic Ocean. The large-scale distribution of SST anomalies is concomitant with the century-scale abrupt change of coral grayness in SCS. Negative correlation exists between the coralgrayness in SCS and precipitation in Guangzhou on the interdecadal scale and the interdecadal precipitation in Guangzhou as reflected by the interdecadaldata of SCS coral grayness shows that the interdecadal variation of south China precipitation changes significantly from phase to phase. The current study aims at contributing in the effort of identifying alternative indexes for climate change in south China on the interdecadal scale and beyond.展开更多
基金Supported by National Science Foundation of China(No.60904070,61272032)the Natural Science Foundation of Zhejiang Province(No.LY12F02002,Y1111101)
文摘UE-Brzier （unified and extended Brzier） basis is the unified form of Brzier-like bases, including polynomial Brzier basis, trigonometric polynomial and hyperbolic polynomial Brzier basis. Similar to the original Brzier-like bases, UE-Brzier basis func-tions are not orthogonal. In this paper, a group of orthogonal basis is constructed based on UE-Brzier basis. The transformation matrices between UE-Brzier basis and the proposed orthogonal basis are also solved.
文摘目的针对低质量浅浮雕表面的噪声现象,提出一种二次联合局部自适应稀疏表示和非局部低秩矩阵近似的浅浮雕优化算法。方法本文方法分两个阶段。第1阶段,将浅浮雕灰度图划分成大小相同的数据块,提取边界块并进行去噪,分别对数据块进行稀疏表示和低秩近似处理。一方面,通过字典学习获得过完备字典和稀疏编码;另一方面,利用K均值聚类算法(K-means)将事先构建的外部字典库划分成k类,从k个簇中心匹配每个数据块的相似块并组成相似矩阵,依次进行低秩近似和特征增强处理。最后通过最小二乘法求解,重建并聚合新建数据块以得到新的高度场。第2阶段与第1阶段的结构相似,主要区别在于改用重建高度场的非局部自身相似性来实现块匹配。结果在不同图像压缩率下(70%,50%,30%),对比本文方法与BM3D(block-matching and 3D filtering)、WNNM(weighted nuclear norm minimization)、STROLLR(sparsifying transform learning and low-rank)、TWSC(trilateral weighted sparse coding)4个平滑降噪方法的浅浮雕重建结果,发现BM3D和STROLLR方法的特征保持虽好,但平滑效果较差,WNNM方法出现模型破损现象,TWSC方法的平滑效果比BM3D和STROLLR方法更好,但特征也同时被光顺化。阴影恢复形状法(shape from shading,SFS)是一种基于图像的3D建模法,但是其重建结果比较粗糙。相比之下,本文方法生成的浅浮雕模型更加清晰直观,在浅浮雕的特征增强和平滑去噪方面都展现出更好的性能。结论本文综合数据块的局部稀疏性和数据块之间的非局部相似性对粗糙的浅浮雕模型进行二次高度场重建。本文方法有效改善了现有浅浮雕模型的质量,提高了模型的整体视觉效果,为浅浮雕的优化提供了新方法。
基金An Open Project for the Laboratory of Forecast Systems at the State Meteorological Center
文摘With daily reanalysis data by NCEP/NCAR and data of tropical cyclones landing over China from 1949 to 2005, the variation of low-frequency oscillations of equatorial pressure and their relationship with tropical cyclones landing over China in the summer half of the years (June through October) are studied for the 57 years, using spectral analysis and correlation analysis. The results show that the summertime equatorial pressure is mainly of periodic oscillations of 5―7 days and 10―30 days and the interannual variation of the intensity of its quasi-biweekly oscillation is significantly positive correlation with the number of tropical cyclones landing over China. The quasi-biweekly oscillation is filtered from daily equatorial pressure in May―November over the 57 years with inverse wavelet transform and the probability for tropical cyclones landing on coastal China within four days before and after the oscillatory valleys of quasi-biweekly pressure at the equator is 59.7% and 73.0% for June to October and July to September respectively. The model of atmospheric circulation for quasi-biweekly oscillatory valleys of equatorial pressure in association with or without tropical cyclones landing over China in July―September is set up with the composite analysis method. When the valleys are associated with (without) landfall, zonal (meridional) circulation prevails in the mid and high latitudes of the Eastern Hemisphere, the high pressure ridge is weak (strong) near the Sea of Okhotsk, the westerly zone is northward (southward), the subtropical high is westward (eastward) in location and strong (weak) in intensity, the cross-equatorial flow is strong (weak) in southeast Asia, Southwest Monsoon is strong (weak) and stronger (weaker) while in the valleys of pressure, being favorable (unfavorable) for tropical cyclones landing over China. The atmospheric circulation model for oscillatory valleys of biweekly equatorial pressure in association with (without) tropical cyclones landing over China, which can reflect the difference of atmospheric circulation between them, is beneficial to medium-term forecasts of tropical cyclones landing over China.
文摘The interdecadal variation of coral grayness in northern South China Sea (SCS) is studied using the annual mean coral grayness in northern SCS from 1789 to 1992 and annual precipitation at Guangzhou from 1908 to 1992 by Singular Spectrum Analysis (SSA), correlation analysis, Mann-Kendall’s abrupt change analysis and composite analysis. The interdecadal variation of south China precipitation as reflected by the series of Guangzhou precipitation rebuilt with the coral grayness is discussed. The results show that the variation of coral grayness in SCS has significant terms of tendency, much-weighted interdecadal variation and weak interannual variation. There was a century-scale abrupt change of coral grayness at the end of the 1880s that changed from positive anomalies to negative anomalies. The global field of SST difference corresponding to the point of abrupt change was negative anomalies over the SCS and neighboring northern Indian Ocean, most of central and western Pacific Ocean and coastal areas of the northern Atlantic Ocean. The large-scale distribution of SST anomalies is concomitant with the century-scale abrupt change of coral grayness in SCS. Negative correlation exists between the coralgrayness in SCS and precipitation in Guangzhou on the interdecadal scale and the interdecadal precipitation in Guangzhou as reflected by the interdecadaldata of SCS coral grayness shows that the interdecadal variation of south China precipitation changes significantly from phase to phase. The current study aims at contributing in the effort of identifying alternative indexes for climate change in south China on the interdecadal scale and beyond.
