Critical rainfall assessment is a very important tool for hazard management of torrents and debris flows in mountainous areas. The Wenchuan Earthquake 2008 caused huge casualties and property damages in the earthquake...Critical rainfall assessment is a very important tool for hazard management of torrents and debris flows in mountainous areas. The Wenchuan Earthquake 2008 caused huge casualties and property damages in the earthquake-stricken area,which also generated large quantities of loose solid materials and increased occurrence probabilities of debris flows. There is an urgent need to quantify the critical rainfall distribution in the area so that better hazard management could be planned and if real time rainfall forecast is available,torrent and debris flow early-warning could be issued in advance. This study is based on 49-year observations (1954-2003) of up to 678 torrent and debris flow events. Detailed contour maps of 1 hour and 24 hour critical rainfalls have been generated (Due to the data limitation,there was insufficient 10 minute critical rainfall to make its contour map). Generally,the contour maps from 1 hour and 24 hours have similar patterns. Three zones with low,medium and high critical rainfalls have been identified. The characteristics of the critical rainfall zones are linked with the local vegetation cover and land forms. Further studies and observations are needed to validate the finding and improve the contour maps.展开更多
Bubble seed image filling is an important prerequisite for the image segmentation of flotation bubble that can be used to improve flotation automatic control. These common image filling algorithms in dealing with comp...Bubble seed image filling is an important prerequisite for the image segmentation of flotation bubble that can be used to improve flotation automatic control. These common image filling algorithms in dealing with complex bubble image exists under-filling and over-filling problems. A new filling algorithm based on boundary point feature and scan lines ~PFSL） is proposed in the paper. The filling a｜gorithm describes these boundary points of image objects by means of chain codes. The features of each boundary point, including convex points, concave points, left points and right points, are defined by the point＇s entrancing chain code and leaving chain code. The algorithm firstly finds out all double-matched boundary points based on the features of boundary points, and fill image objects by these double-matched boundary points on scan lines. Experimental results of bubble seed image filling show that under-filling and over-filling problem can be eliminated by the proposed algorithm.展开更多
In this paper, the authors present ConGrap, a novel contour detector for finding closed contours with semantic connections. Based on gradient-based edge detection, a Gradient Map is generated to store the orientation ...In this paper, the authors present ConGrap, a novel contour detector for finding closed contours with semantic connections. Based on gradient-based edge detection, a Gradient Map is generated to store the orientation of every edge pixel. Using the edge image and the generated Gradient Map, ConGrap separates the image into semantic parts and objects. Each edge pixel is mapped to a contour by a three-stage hierarchical analysis of neighbored pixels and ensures the closing of contours. A final post-process of ConGrap extracts the contour borderlines and merges them, if they semantically relate to each other. In contrast to common edge and contour detections, ConGrap not only produces an edge image, but also provides additional information （e.g., the borderline pixel coordinates the bounding box, etc.） for every contour. Additionally, the resulting contour image provides closed contours without discontinuities and merged regions with semantic connections. Consequently, the ConGrap contour image can be seen as an enhanced edge image as well as a kind of segmentation and object recognition.展开更多
The weighted graphs, where the edge weights are positive numbers, are considered. The authors obtain some lower bounds on the spectral radius and the Laplacian spectral radius of weighted graphs, and characterize the ...The weighted graphs, where the edge weights are positive numbers, are considered. The authors obtain some lower bounds on the spectral radius and the Laplacian spectral radius of weighted graphs, and characterize the graphs for which the bounds are attained. Moreover, some known lower bounds on the spectral radius and the Laplacian spectral radius of unweighted graphs can be deduced from the bounds.展开更多
This paper is devoted to determining the structures and properties of one-Lee weight codes and two-Lee weight projective codes Ck1,k2,k3 over p IF+ v IFp with type p2k1pk2pk3. The authors introduce a distance-preservi...This paper is devoted to determining the structures and properties of one-Lee weight codes and two-Lee weight projective codes Ck1,k2,k3 over p IF+ v IFp with type p2k1pk2pk3. The authors introduce a distance-preserving Gray map from( IFp + v IFp)nto2np. By the Gray map, the authors construct a family of optimal one-Hamming weight p-ary linear codes from one-Lee weight codes over IFp+ v IFp, which attain the Plotkin bound and the Griesmer bound. The authors also obtain a class of optimal p-ary linear codes from two-Lee weight projective codes over IFp + vIFp, which meet the Griesmer bound.展开更多
We consider even factors with a bounded number of components in the n-times iterated line graphs L^n(G). We present a characterization of a simple graph G such that L^n(G) has an even factor with at most k components,...We consider even factors with a bounded number of components in the n-times iterated line graphs L^n(G). We present a characterization of a simple graph G such that L^n(G) has an even factor with at most k components, based on the existence of a certain type of subgraphs in G. Moreover, we use this result to give some upper bounds for the minimum number of components of even factors in L^n(G) and also show that the minimum number of components of even factors in L^n(G) is stable under the closure operation on a claw-free graph G, which extends some known results. Our results show that it seems to be NP-hard to determine the minimum number of components of even factors of iterated line graphs. We also propose some problems for further research.展开更多
基金financially supported by the Scholarship of Knowledge Innovation Project, Chinese Academy of Sciences (KZCX2-YW-332)
文摘Critical rainfall assessment is a very important tool for hazard management of torrents and debris flows in mountainous areas. The Wenchuan Earthquake 2008 caused huge casualties and property damages in the earthquake-stricken area,which also generated large quantities of loose solid materials and increased occurrence probabilities of debris flows. There is an urgent need to quantify the critical rainfall distribution in the area so that better hazard management could be planned and if real time rainfall forecast is available,torrent and debris flow early-warning could be issued in advance. This study is based on 49-year observations (1954-2003) of up to 678 torrent and debris flow events. Detailed contour maps of 1 hour and 24 hour critical rainfalls have been generated (Due to the data limitation,there was insufficient 10 minute critical rainfall to make its contour map). Generally,the contour maps from 1 hour and 24 hours have similar patterns. Three zones with low,medium and high critical rainfalls have been identified. The characteristics of the critical rainfall zones are linked with the local vegetation cover and land forms. Further studies and observations are needed to validate the finding and improve the contour maps.
基金supported by the National Science & Technology Support Plan of China (No. 2009BAB48B02)the Basic Scientific Research Foundation for Institution of Higher Education (No.2008AA062101)
文摘Bubble seed image filling is an important prerequisite for the image segmentation of flotation bubble that can be used to improve flotation automatic control. These common image filling algorithms in dealing with complex bubble image exists under-filling and over-filling problems. A new filling algorithm based on boundary point feature and scan lines ~PFSL） is proposed in the paper. The filling a｜gorithm describes these boundary points of image objects by means of chain codes. The features of each boundary point, including convex points, concave points, left points and right points, are defined by the point＇s entrancing chain code and leaving chain code. The algorithm firstly finds out all double-matched boundary points based on the features of boundary points, and fill image objects by these double-matched boundary points on scan lines. Experimental results of bubble seed image filling show that under-filling and over-filling problem can be eliminated by the proposed algorithm.
文摘In this paper, the authors present ConGrap, a novel contour detector for finding closed contours with semantic connections. Based on gradient-based edge detection, a Gradient Map is generated to store the orientation of every edge pixel. Using the edge image and the generated Gradient Map, ConGrap separates the image into semantic parts and objects. Each edge pixel is mapped to a contour by a three-stage hierarchical analysis of neighbored pixels and ensures the closing of contours. A final post-process of ConGrap extracts the contour borderlines and merges them, if they semantically relate to each other. In contrast to common edge and contour detections, ConGrap not only produces an edge image, but also provides additional information （e.g., the borderline pixel coordinates the bounding box, etc.） for every contour. Additionally, the resulting contour image provides closed contours without discontinuities and merged regions with semantic connections. Consequently, the ConGrap contour image can be seen as an enhanced edge image as well as a kind of segmentation and object recognition.
基金supported by the National Natural Science Foundation of China(Nos.11101027,11071115,10971114,10990011,11171097)the Fundamental Research Funds for the Central Universities of China(No.2011JBM136)
文摘The weighted graphs, where the edge weights are positive numbers, are considered. The authors obtain some lower bounds on the spectral radius and the Laplacian spectral radius of weighted graphs, and characterize the graphs for which the bounds are attained. Moreover, some known lower bounds on the spectral radius and the Laplacian spectral radius of unweighted graphs can be deduced from the bounds.
基金supported by the National Natural Science Foundation of China under Grant No.61202068Talented youth Fund of Anhui Province Universities under Grant No.2012SQRL020ZDthe Technology Foundation for Selected Overseas Chinese Scholar,Ministry of Personnel of China under Grant No.05015133
文摘This paper is devoted to determining the structures and properties of one-Lee weight codes and two-Lee weight projective codes Ck1,k2,k3 over p IF+ v IFp with type p2k1pk2pk3. The authors introduce a distance-preserving Gray map from( IFp + v IFp)nto2np. By the Gray map, the authors construct a family of optimal one-Hamming weight p-ary linear codes from one-Lee weight codes over IFp+ v IFp, which attain the Plotkin bound and the Griesmer bound. The authors also obtain a class of optimal p-ary linear codes from two-Lee weight projective codes over IFp + vIFp, which meet the Griesmer bound.
基金supported by National Natural Science Foundation of China (Grant Nos. 11471037 and 11171129)Specialized Research Fund for the Doctoral Program of Higher Education (Grant No. 20131101110048)
文摘We consider even factors with a bounded number of components in the n-times iterated line graphs L^n(G). We present a characterization of a simple graph G such that L^n(G) has an even factor with at most k components, based on the existence of a certain type of subgraphs in G. Moreover, we use this result to give some upper bounds for the minimum number of components of even factors in L^n(G) and also show that the minimum number of components of even factors in L^n(G) is stable under the closure operation on a claw-free graph G, which extends some known results. Our results show that it seems to be NP-hard to determine the minimum number of components of even factors of iterated line graphs. We also propose some problems for further research.
