采用趋势分析法、Mann-Kendall突变分析法、小波分析法和时态GIS对三江平原1952—2012年间的61 a降水量的时空变异特征进行分析。结果表明:时间上,5个主要行政区的降水量序列在时间整体上变化趋势不明显,而在时间序列内部存在不同突变趋...采用趋势分析法、Mann-Kendall突变分析法、小波分析法和时态GIS对三江平原1952—2012年间的61 a降水量的时空变异特征进行分析。结果表明:时间上,5个主要行政区的降水量序列在时间整体上变化趋势不明显,而在时间序列内部存在不同突变趋势,存在以28、22、15、6 a 4个时段为主周期的波动状态;整个三江平原降水量序列在时间整体上变化趋势也不明显,但在时间序列内部表现出突变趋势,即1955年开始呈下降趋势,至1979年开始呈上升趋势,到1997年又呈下降趋势,存在与各行政分区主周期相同的波动状态。空间上,三江平原降水量空间分布变化趋势表现出明显的差异性,即1952—1954年从北到南呈现中间多两端少的变化趋势,而1955—1978年从北到南呈现两端多中间少的变化趋势,1979—2012年也呈现北多南少、东多西少的变化趋势。5个主要行政区及三江平原1952—1954年和1997—2012年两个时段内的多年平均降水量均少于1955—1996年间的多年平均降水量。展开更多
Rail fastener positioning method has high requirements for image quality and positioning accuracy.Therefore,a rail fastener positioning method based on gray mutation is proposed.Firstly,the image is denoised by an imp...Rail fastener positioning method has high requirements for image quality and positioning accuracy.Therefore,a rail fastener positioning method based on gray mutation is proposed.Firstly,the image is denoised by an improved median filter.Then,according to the characteristics of image frequency domain,the image is decomposed by wavelet transfrom to extract low-frequency component,and the low-frequency component is filtered and processed by gamma transformation to reduce the influence of natural environment factors on image quality.After that,according to the change rule of gray-scale values of different regions in the image,the gray-scale mutation in column and line directions of the image is statistically analyzed,and then the rail surface and the sleeper are located.Finally,the fastener area is accurately located by using the position relationship of the rail surface,the sleeper and the fastener in the image.The experimental results show that the positioning accuracy of the proposed method is 93.19%,which can quickly and effectively locate the fastener region,and has strong environmental adaptability,robustness and practicability.展开更多
文摘采用趋势分析法、Mann-Kendall突变分析法、小波分析法和时态GIS对三江平原1952—2012年间的61 a降水量的时空变异特征进行分析。结果表明:时间上,5个主要行政区的降水量序列在时间整体上变化趋势不明显,而在时间序列内部存在不同突变趋势,存在以28、22、15、6 a 4个时段为主周期的波动状态;整个三江平原降水量序列在时间整体上变化趋势也不明显,但在时间序列内部表现出突变趋势,即1955年开始呈下降趋势,至1979年开始呈上升趋势,到1997年又呈下降趋势,存在与各行政分区主周期相同的波动状态。空间上,三江平原降水量空间分布变化趋势表现出明显的差异性,即1952—1954年从北到南呈现中间多两端少的变化趋势,而1955—1978年从北到南呈现两端多中间少的变化趋势,1979—2012年也呈现北多南少、东多西少的变化趋势。5个主要行政区及三江平原1952—1954年和1997—2012年两个时段内的多年平均降水量均少于1955—1996年间的多年平均降水量。
基金National Natural Science Foundation of China(Nos.61616202,61461203)Ministry of Education Innovation Team Development Plan(No.IRT_16R36)Plateau Information Engineering and Control Key Practice Laboratory Open Project Fund of Gansu Province(No.201611105)。
文摘Rail fastener positioning method has high requirements for image quality and positioning accuracy.Therefore,a rail fastener positioning method based on gray mutation is proposed.Firstly,the image is denoised by an improved median filter.Then,according to the characteristics of image frequency domain,the image is decomposed by wavelet transfrom to extract low-frequency component,and the low-frequency component is filtered and processed by gamma transformation to reduce the influence of natural environment factors on image quality.After that,according to the change rule of gray-scale values of different regions in the image,the gray-scale mutation in column and line directions of the image is statistically analyzed,and then the rail surface and the sleeper are located.Finally,the fastener area is accurately located by using the position relationship of the rail surface,the sleeper and the fastener in the image.The experimental results show that the positioning accuracy of the proposed method is 93.19%,which can quickly and effectively locate the fastener region,and has strong environmental adaptability,robustness and practicability.
